COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT
WATER QUALITY CONTROL COMMISSION
5 CCR 1002-35
REGULATION NO. 35
CLASSIFICATIONS AND NUMERIC STANDARDS
FOR
GUNNISON AND LOWER DOLORES RIVER BASINS
ADOPTED:	January 10, 1983
EFFECTIVE:	March 2, 1983
AMENDED:	December 12, 1983
EFFECTIVE:	January 30, 1984
TRIENNIAL REVIEW:	April 7, 1986
AMENDED:	September 12, 1986
EFFECTIVE:	October 30, 1986
AMENDED:	March 9, 1988
EFFECTIVE:	April 30, 1988
AMENDED:	August 1, 1988
EFFECTIVE:	September 30, 1988
AMENDED:	December 4, 1990
EFFECTIVE:	January 30, 1991
AMENDED:	December 7, 1992
EFFECTIVE:	January 30, 1993
AMENDED:	March 1, 1993
EFFECTIVE:	April 30, 1993
AMENDED:	February 13, 1995
EFFECTIVE:	March 30, 1995
AMENDED:	July 10, 1995
EFFECTIVE:	August 30, 1995
AMENDED:	December 11, 1995
EFFECTIVE:	January 30, 1996
AMENDED:	July 14, 1997
EFFECTIVE:	August 30, 1997
AMENDED:	July 14, 1997
EFFECTIVE:	August 30, 1997
AMENDED:	April 13, 1998
EFFECTIVE:	May 30, 1998
AMENDED:	December 14, 1998
EFFECTIVE:	January 30, 1999
AMENDED:	October 9, 2001
EFFECTIVE:	February 20, 2002
AMENDED:	December 12, 2005
EFFECTIVE:	March 2, 2006
AMENDED:	August 14, 2006
EFFECTIVE:	January 1, 2007
AMENDED:	February 12, 2007
EFFECTIVE:	July 1, 2007

COLORADO DEPARTMENT OF PUBLIC HEALTH AND ENVIRONMENT 
WATER QUALITY CONTROL COMMISSION 
5 CCR 1002-35
REGULATION NO. 35
CLASSIFICATIONS AND NUMERIC STANDARDS 
FOR 
GUNNISON AND LOWER DOLORES RIVER BASINS
35.1	AUTHORITY
These regulations are promulgated pursuant to section 25-8-101 et seq. C.R.S., as amended, and in particular, 25-8-203 and 25-8-204. 
35.2	PURPOSE
These regulations establish classifications and numeric standards for the Gunnison River/Lower Dolores River Basins, including all tributaries and standing bodies of water.  This includes all or parts of Gunnison, Delta, Montrose, Ouray, Mesa, Saguache and Hinsdale Counties.  This also includes the lower Dolores River and its tributaries in Dolores, Montrose, Mesa and San Miguel Counties.  The classifications identify the actual beneficial uses of the water.  The numeric standards are assigned to determine the allowable concentrations of various parameters.  Discharge permits will be issued by the Water Quality Control Division to comply with basic, narrative, and numeric standards and control regulations so that all discharges to waters of the state protect the classified uses.  (See Regulation No. 31, section 31.14).  It is intended that these and all other stream classifications and numeric standards be used in conjunction with and be an integral part of Regulation No.31 Basic Standards and Methodologies for Surface Water. 
35.3	INTRODUCTION
These regulations and tables present the classifications and numeric standards assigned to stream segments listed in the attached tables (See section 35.6(4)).  As additional stream segments are classified and numeric standards for designated parameters are assigned for this drainage system, they will be added to or replace the numeric standards in the tables in section 35.6(4).  Any additions or revisions of classifications or numeric standards can be accomplished only after public hearing by the Commission and proper consideration of evidence and testimony as specified by the statute and the "basic regulations". 
35.4	DEFINITIONS
See the Colorado Water Quality Control Act and the codified water quality regulations for definitions. 
35.5	BASIC STANDARDS
(1)	TEMPERATURE
All waters of the Gunnison/Lower Dolores River Basins are subject to the following standard for temperature.  (Discharges regulated by permits, which are within the permit limitations, shall not be subject to enforcement proceedings under this standard).  Temperature shall maintain a normal pattern of diurnal and seasonal fluctuations with no abrupt changes and shall have no increase in temperature of a magnitude, rate, and duration deemed deleterious to the resident aquatic life.  This standard shall not be interpreted or applied in a manner inconsistent with section 25-8-104, C.R.S.  Effective until December 31, 2011:  Segments or portions of segments that are first, second or third order streams above 7000 feet elevation and classified Aquatic Life cold 1 or 2 shall have a chronic temperature standard of 17 ºC (MWAT) with no acute standard. The following waters designated as Gold Medal fisheries by the Colorado Wildlife Commission shall have a chronic temperature standard of 18.2 ºC (MWAT):
▪	Gunnison River (brown and rainbow trout fishery) from 200 yards downstream of Crystal Reservoir dam to the confluence with the North Fork of the Gunnison.  
Other cold class 1 or 2 segments or portions of segments shall have a chronic temperature standard of 20 ºC (MWAT) with no acute standard.  Segments that are classified Aquatic Life warm 1 or 2 shall have a chronic temperature standard of 30 ºC (MWAT) with no acute standard.
(2)	QUALIFIERS
See Basic Standards and Methodologies for Surface Water for a listing of organic standards at 31.11 and metal standards found at 31.16 Table III.  The column in the tables headed “Water + Fish” are presumptively applied to all aquatic life class 1 streams which also have a water supply classification, and are applied to aquatic life class 2 streams which also have a water supply classification, on a case-by-case basis as shown in the Tables 35.6(4).  The column in the tables at 31.11 and 31.16 Table III headed “Fish Ingestion” is presumptively applied to all aquatic life class 1 streams which do not have a water supply classification, and are applied to aquatic life class 2 streams which do not have a water supply classification, on a case-by-case basis as shown in Tables 35.6(4). 
(3)	URANIUM
(a)	All waters of the Gunnison/Lower Dolores River Basin, are subject to the following basic standard for uranium, unless otherwise specified by a water quality standard applicable to a particular segment.  However, discharges of uranium regulated by permits which are within these permit limitations shall not be a basis for enforcement proceedings under this basic standard. 
(b)	Uranium level in surface waters shall be maintained at the lowest practicable level. 
(c) 	In no case shall uranium levels in waters assigned a water supply classification be increased by any cause attributable to municipal, industrial, or agricultural discharges so as to exceed 30 µg/l or naturally-occurring concentrations (as determined by the State of Colorado), whichever is greater. 
(d)	In no case shall uranium levels in waters assigned a water supply classification be increased by a cause attributable to municipal, industrial, or agricultural discharges so as to exceed 30 µg/l where naturally-occurring concentrations are less than 30 µg/l. 
35.6	TABLES
(1)	Introduction
The numeric standards for various parameters in the attached tables were assigned by the Commission after a careful analysis of the data presented on actual stream conditions and on actual and potential water uses. 
Numeric standards are not assigned for all parameters listed in the tables attached to Regulation No. 31.  If additional numeric standards are found to be needed during future periodic reviews, they can be assigned by following the proper hearing procedures. 
(2)	Abbreviations:
The following abbreviations are used in the attached tables: 
ac 	= 	acute (1-day) 
Ag 	= 	Silver 
Al 	= 	Aluminum 
As 	= 	Arsenic 
B 	= 	Boron 
Ba 	= 	Barium 
Be 	= 	Beryllium 
Cd 	= 	Cadmium 
ch 	= 	Chronic (30-day) 
Cl 	= 	Chloride 
Cl2	= 	Residual chlorine 
CN 	= 	free cyanide 
CrIII 	= 	Trivalent chromium 
CrVI 	= 	Hexavalent chromium 
Cu 	= 	Copper 
dis 	= 	dissolved 
D.O. 	= 	dissolved oxygen 
E. coli 	=  	escherichia coli 
F 	= 	fluoride 
Fe 	= 	iron 
Hg 	= 	mercury 
Mg/l 	= 	milligrams per liter 
ml 	= 	milliliters 
Mn 	= 	manganese 
NH3	= 	un-ionized ammonia as N(nitrogen) 
Ni 	= 	nickel 
NO2	= 	nitrite as N (nitrogen) 
NO3	= 	nitrate as N (nitrogen) 
OW 	= 	outstanding waters 
P 	= 	phosphorus 
Pb 	= 	lead 
S 	= 	sulfide as undissociated H2S (hydrogen sulfide) 
Sb 	= 	Antimony 
sc Se 	= 	sculpin selenium 
SO4	= 	sulfate 
sp 	= 	spawning 
Tl 	= 	thallium 
Tr 	= 	trout 
Trec 	= 	total recoverable 
TVS 	= 	table value standard 
U 	= 	uranium 
µg/l 	= 	micrograms per liter 
UP 	= 	use-protected 
Zn 	= 	zinc 
In addition, the following abbreviations are used: 
Fe(ch)  = WS(dis) 
Mn(ch) = WS(dis) 
SO4  = WS 
These abbreviations mean: For all surface waters with an actual water supply use, the less restrictive of the following two options shall apply as numerical standards, as specified in the Basic Standards and Methodologies at 31.16 Table II and III: 
(1)	existing quality as of January 1, 2000; or 
(2)	Iron   = 300 µg/l (dissolved)
Manganese  = 50 µg/l (dissolved) 
SO4   = 250 mg/l 
For all surface waters with a “water supply” classification that are not in actual use as a water supply, no water supply standards are applied for iron, manganese or sulfate, unless the Commission determines as the result of a site-specific rulemaking hearing that such standards are appropriate. 
(3)	Table Value Standards
In certain instances in the attached tables, the designation "TVS" is used to indicate that for a particular parameter a "table value standard" has been adopted.  This designation refers to numerical criteria set forth in the Basic Standards and Methodologies for Surface Water.  The criteria for which the TVS are applicable are on the following table. 
TABLE VALUE STANDARDS
 (Concentrations in µg/l unless noted) 
____________________________________________________________________________ 
PARAMETER(1)   		TABLE VALUE STANDARDS (2)(3)
____________________________________________________________________________ 
Ammonia (4)	Cold Water 

 	Warm Water 

______________ 	_______________________________________________________ 	
NH3 = old TVS  	Cold Water Acute = 0.43/FT/FPH/2(4 old) in mg/l (N) 	
 	Warm Water Acute = 0.62/FT/FPH/2(4 old) in mg/ (N) 	
______________	_______________________________________________________	
Cadmium	Acute  = (1.136672-[ln(hardness) x (0.041838)] )x e0.9151[ln(hardness)]-3.1485	
	Acute(Trout) = (1.136672-[ln(hardness)x (0.041838)] )x e0.9151[ln(hardness)]-3.6236	
	Chronic = (1.101672-[ln(hardness) x(0.041838)] x e0.7998[ln(hardness)]-4.4451	
______________	_______________________________________________________	
Chromium III(5)	Acute = e(0.819[ln(hardness)]+2.5736)	
	Chronic = e(0.819[ln(hardness)]+0.5340)	
	Acute = 16	
______________	_______________________________________________________	
Chromium VI(5)	Chronic = 11	
______________	_______________________________________________________	
Copper	Acute = e(0.9422[ln(hardness)]-1.7408)	
	Chronic = e(0.8545[ln(hardness)]-1.7428)	
______________	_______________________________________________________	
Lead	Acute = (1.46203-[(ln hardness)*(0.145712)])*e(1.273[ln(hardness)]-1.46)	
	Chronic = (1.46203-[(ln hardness)*(0.145712)])*e(1.273[ln(hardness)]-4.705)	
______________	_______________________________________________________	
Manganese	Acute = e(0.3331[ln(hardness)]+6.4676)	
	Chronic = e(0.3331 [ln (hardness)]+5.8743)	
______________	_______________________________________________________	
Nickel	Acute = e(0.846[ln(hardness)]+2.253)	
	Chronic = e(0.846[ln(hardness)]+0.0554)	
______________	_______________________________________________________	
Selenium(6)	Acute = 18.4	
	Chronic = 4.6	
______________	_______________________________________________________	
Silver	Acute = ½e(1.72[ln(hardness)]-6.52)	
	Chronic = e(1.72[ln(hardness)]-9.06)	
	Chronic = e(1.72[ln(hardness)]-9.06)	
	Chronic(Trout) = e(1.72[ln(hardness)]-10.51)	
______________	_______________________________________________________	
Uranium	Acute = e(1.1021[ln(hardness)]+2.7088)	
	Chronic = e(1.1021[ln(hardness)]+2.2382)	
______________	_______________________________________________________	
Zinc	Acute = 0.978 e(0.8525[ln(hardness)]+1.0617)	
	Chronic = 0.986 e(0.8525[ln(hardness)]+0.9109)	
	Chronic (sculpin) = e(2.227[ln(hardness)]-5.604)	
____________________________________________________________________________________
TABLE VALUE STANDARDS - FOOTNOTES 
(1) 	Metals are stated as dissolved unless otherwise specified. 
(2) 	Hardness values to be used in equations are in mg/l as calcium carbonate and shall be no greater than 400mg/L.  The hardness values used in calculating the appropriate metal standard should be based on the lower 95 per cent confidence limit of the mean hardness value at the periodic low flow criteria as determined from a regression analysis of site-specific data.  Where insufficient site-specific data exists to define the mean hardness value at the periodic low flow criteria, representative regional data shall be used to perform the regression analysis.  Where a regression analysis is not appropriate, a site-specific method should be used.  In calculating a hardness value, regression analyses should not be extrapolated past the point that data exist. 
(3) 	Both acute and chronic numbers adopted as stream standards are levels not to be exceeded more than once every three years on the average. 
(4 old) 	FT = 100.03(20-TCAP);
Where TCAP is ≤ T ≤ 30
FT = 100.03(20-T); 
Where 0 is ≤ T ≤ TCAP
TCAP = 20o C cold water aquatic life species present
TCAP = 25o C cold water aquatic life species absent
FPH = 1; Where 8 ≤pH ≤ 9
FPH = 1 + 10(7.4-pH); 
             1.25                Where 6.5 ≤ pH ≤ 8
FPH means the acute pH adjustment factor, defined by the above formulas.
FT Means the acute temperature adjustment factor, defined by the above formulas.
T means temperature measured in degrees celsius.
TCAP means temperature CAP; the maximum temperature which affects the toxicity of ammonia to salmonid and non-salmonid fish groups. 
NOTE: If the calculated acute value is less than the chronic value, then the chronic value shall be used as the acute standard.  
(4)	For acute conditions the default assumption is that salmonids could be present in cold water segments and should be protected, and that salmonids do not need to be protected in warm water segments.  For chronic conditions, the default assumptions are that early life stages could be present all year in cold water segments and should be protected.  In warm water segments the default assumption is that early life stages are present and should be protected only from April 1 through August 31.  These assumptions can be modified by the commission on a site-specific basis where appropriate evidence is submitted. 
(5)	Unless the stability of the chromium valence state in receiving waters can be clearly demonstrated, the standard for chromium should be in terms of chromium VI.  In no case can the sum of the instream levels of Hexavalent and Trivalent Chromium exceed the water supply standard of 50ug/l total chromium in those waters classified for domestic water use. 
(6)	Selenium is a bioaccumulative metal and subject to a range of toxicity values depending upon numerous site-specific variables. 
[INSERT TABLES]
35.7-35.10 	RESERVED
35.11	STATEMENT OF BASIS AND PURPOSE
I.	Introduction
These stream classifications and water quality standards for State Waters of the Gunnison River Basin including all tributaries and standing bodies of water in all or parts of the Gunnison, Delta, Montrose, Ouray, Mesa, Saguache, and Hinsdale Counties and the Lower Dolores River and its tributaries in Dolores and San Miguel Counties implement requirements of the Colorado Water Quality Control Act C.R.S. 1973, 25-8-101 et seq. (Cum. Supp. 1981).  They also represent the implementation of the Commission’s Regulations Establishing Basic Standards and an Antidegradation Standard and Establishing a System for Classifying State Waters, for Assigning Standards, and for Granting Temporary Modifications (the “Basic Regulations”) 
The Basic Regulations establish a system for the classification of State Waters according to the beneficial uses for which they are suitable or are to become suitable, and for assigning specific numerical water quality standards according to such classifications.  Because these stream classifications and standards implement the Basic Regulations, the statement of basis and purpose (Section 3.1.16) of those regulations must be referred to for a complete understanding of the basis and purpose of the regulations adopted herein.  Therefore, Section 3.1.16 of the Basic Regulations is incorporated by reference.  The focus of this statement of basis and purpose is on the scientific and technological rationale for the specific classifications and standards in the Gunnison River Basin. 
Public participation was a significant factor in the development of these regulations.  A lengthy record was built through public hearings held on November 16-18, 1981.  A total of 10 entities requested and were granted party status by the Commission in accordance with the Commission’s Procedural Regulations (Cum. Supp. 1980).  The record established in these hearings forms the basis for the classifications and standards adopted. 
II.	General Considerations
These regulation are not adopted as control regulations.  Stream classifications and water quality standards are specifically distinguished from control regulations in the Water Quality Control Act, and they need not be adopted as control regulations pursuant to the statutory scheme. 
III.	Definition of Stream Segments
1. 	For purposes of adopting classifications and water quality standards, the streams and water bodies are identified according to river basin and specific water segments. 
2. 	Within each river basin, specific water segments are defined, for which use classifications and numeric water quality standards, if appropriate, are adopted.  These segments may constitute a specified stretch of a river mainstem, a specific tributary, a specific lake or reservoir, or a generally defined grouping of waters within the basin (e.g., a specific mainstem segment and all tributaries flowing into that mainstem segment). 
3. 	Segments are generally defined according to the points at which the use, water quality, or other stream characteristics change significantly enough to require a change in use classification and/or water quality standards.  In many cases, such transition points can be specifically identified from available data.  In other cases the delineation of segments is based upon best judgments of the points where instream changes in uses, water quality, or other stream characteristics occur. 
IV.	Use Classifications and Standards -- Generally
1. 	Initially, recommendations for stream segmentation and use classifications are a result of input from 208 plans, water quality data and reports, the Division of Wildlife, and personal knowledge.  After a basic outline of stream segments and use classifications was prepared, water quality data from a variety of sources was compared against the “table value” for the proposed use.  “Table value” refers to the four tables attached to the “Basic Regulations”.  In general, if the mean plus one standard deviation (x + s) of the available data for the segment indicated that a particular parameter did not exceed the “table value” for that recommended use, the “table value” was listed as the recommended standard for the parameter.  If the x + s computation indicated that the instream concentrations of the parameter exceeded the “table value” and yet the use to be protected by that parameter was in place, then the x + s value was recommended as the standard for that parameter. 
Conversely, if the ambient quality (x + s) for a certain parameter exceeded the “table value” for the protection of a use, and there is information that the proposed use is not in place, the use classification was modified or temporary modifications to the parameters were established.  Ambient quality is generally defined as the quality attributable to natural conditions and/or uncontrollable non-point sources. 
2. 	The use classifications have been established in accordance with the provisions of Section 203 of the Water Quality Control Act and Section 3.1.6 and 3.1.13 of the Basic Regulations. 
3. 	In most cases upstream segments of a stream are generally the same as, or higher in classification, than downstream segments in order to protect downstream uses.  In a few cases, tributaries are classified at lower classifications than mainstems where flow from tributaries does not threaten the quality of mainstem waters where the evidence indicates that lower classification for the tributaries is appropriate.  In either case, permits should be written to assure compliance with Water Quality Standards and any stream segment affected by a discharge. 
4.	
A. 	The Commission has determined that it has the authority to assign the classification “High Quality Waters - Class 1" and “High Quality Waters - Class 2" where the evidence indicates that the requirements of Sections 3.1.13(1)(e) of the basic regulations are met.   A question exists as to whether existing diversion structures can be maintained consistent with a “High Quality - Class 1” designation.  Because of the questions regarding authority to regulate diversions, the Class 1 designation was deemed potentially too rigid.  The Commission recognizes its authority to upgrade these segments if and when it is appropriate to do so.  Streams have been classified “High Quality - Class 2” for one or more of the following reasons: 
(a) 	to facilitate the enjoyment and use of the scenic and natural resources of the State in accordance with the Legislative Declaration of the Colorado Water Quality Control Act (25-8-102(1) C.R.S. 1973. 
(b) 	to provide a high degree of protection deserving of wilderness areas which are a resource providing a unique experience. 
(c) 	to protect threatened species or to protect wild scenic river study areas or wilderness areas. 
The concern of the United States Forest Service that High Quality 2 classification will unduly burden their management of multiple use areas is not well founded.  This is because activities on Forest Service land, i.e. grazing, mineral exploration, trail and road maintenance, are considered as a historical impact upon existing ambient water quality conditions and are non point sources which are presently not subject to any Water Quality Control Commission regulations. 
B. 	The “High Quality - Class 2" classification was proposed by the Gunnison River Coalition and other witnesses for a number of segments.  These proposals have been rejected, and the segments classified for specific uses, for the following reasons: 
(a)	High quality classifications represent extraordinary categories, and their use is optional at the discretion of the Commission; 
(b)	It is important in these cases to assign specific water quality standards to protect the highest specific use classifications, and only specific use classifications provide the mechanism for assigning such standards. 
5. 	In accordance with 25-8-104, C.R.S. 1973, the Commission intends that no provision of this regulation shall be interpreted so as to supercede, abrogate, or impair rights to divert water and apply water to beneficial uses. 
6. 	Recreation -- Class 1 and Class 2
In addition to the significant distinction between Recreation - Class 1 and Recreation - Class 2 as defined in Section 3.1.13(1) of the Basic Regulations, the difference between the two classifications in terms of water quality standards is the fecal coliform parameter.  Recreation - Class 1 generally has a standard of 200 fecal coliform per 100 ml; Recreation - Class 2 generally has a standard of 2000 fecal coliform per 100 ml. 
In accordance with the Colorado Water Quality Control Act, the Commission has decided to classify as “Recreation - Class 2” those stream segments where primary contact recreation does not exist and cannot be reasonably expected to exist in the future, regardless of water quality.  The Commission has decided to classify as “Recreation - Class 1” only those stream segments where primary contact recreation actually exists, or could reasonably be expected to occur.  The reasons for the application of Recreation Class 2 are as follows: 
(a) 	The mountain streams in this region are generally unsuitable for primary contact recreation because of low water temperature and low stream flows. 
(b) 	Fecal coliform is an indicator organism.  Its presence does not always indicate the presence of pathogens.  This depends on the source of the fecal coliform.  If the source is agricultural runoff as opposed to human sewage, there may be no health hazard and therefore no significant need to reduce the presence of fecal coliform to the 200 per 100 ml. level.  Also, control of nonpoint sources is very difficult. 
(c) 	Treating sewage to meet the 200 per 100 ml. level generally means the treatment plant must heavily chlorinate its effluent to meet the limitation.  The presence of chlorine in the effluent can be significantly detrimental to aquatic life.  Post-treatment of effluent to meet the residual chlorine standard is expensive and often results in the addition of more chemicals which have a negative effect on water quality and can be detrimental to aquatic life.  Therefore, reducing the need for chlorine is beneficial to aquatic life. 
(d) 	Even where a treatment plant in this region might treat its effluent to attain the standard of 200 per 100 ml., agricultural runoff and irrigation return flows below the plant may result in the rapid increase of fecal coliform levels.  Therefore, the benefits of further treatment are questionable. 
(e) 	The fecal coliform standard of 2000 per 100 ml. has been established to provide general public health protection.  There is no significant impact on domestic drinking water treatment plants because they provide complete disinfection.  The standard of 200 per 100 ml. is not intended to protect the water supply classification. 
7. 	Water Supply Classification
The Commission finds that Colorado is a water short state and that it is experiencing considerable growth which places additional burdens on already scarce water supplies.  These considerations mitigate in favor of a conservative approach to protecting future water supplies.  Where existing water quality is adequate to protect this use, and in the absence of dischargers to these segments or testimony in opposition to such classification, the water supply use has been assigned because it is reasonable to expect that it may exist in the future in such cases.  For stream segments that flow through, or in the vicinity of, municipalities, this conclusion is further justified, since there is a reasonable probability that the use exists or will exist.  Where the water supply classification has been opposed, the Commission has evaluated the evidence on a site specific basis, and in many cases the classification has been removed. 
V. 	Water Quality Standards -- Generally
1. 	The water quality standards for classified stream segments are defined as numeric values for specific water quality parameters.  These numeric standards are adopted as the limits for chemical constituents and other parameters necessary to protect adequately the classified uses in all stream segments. 
2. 	Not all of the parameters listed in the “Tables” appended to the Basic Regulations are assigned as water quality standards.  This complies with Section 3.1.7(c) of the Basic Regulations. 
Numeric standards have been assigned for the full range of parameters to a number of segments where little or no data existed specific to the segment.  In these cases, there was reason to believe that the classified uses were in place or could be reasonably expected, and that the ambient water quality was as good as or better than the numeric standards assigned. 
3. 	A numeric standard for the temperature parameter has been adopted as a basic standard applicable to all waters of the region in the same manner as the basic standards in Section 3.1.11 of the Basic Regulations. 
The standard of a 3 C temperature increase above ambient water temperature as defined is generally valid based on the data regarding that temperature necessary to support an “Aquatic Life - Class 1" fishery.  The standard takes into account daily and seasonal fluctuations; however, it is also recognized that the 3 C limitation as defined is only appropriate as a guideline and cannot be rigidly applied if the intention is to protect aquatic life.  In winter, for example, warm water discharges may be beneficial to aquatic life.  It is the intention of the Commission in adopting the standard to prevent radical temperature changes in short periods of time which are detrimental to aquatic life. 
4. 	Numeric standards for seventeen organic parameters have been adopted as basic standards applicable to all waters of the region in the same manner as the basic standards in Section 3.1.11 of the Basic Regulations.  These standards are essential to a program designed to protect the waters of the State regardless of specific use classifications because they describe the fundamental conditions that all waters must meet to be suitable for any use. 
It is the decision of the Commission to adopt these standards as basic standards because the presence of the organic parameters is not generally suspected.  Also, the values assigned for these standards are not detectable using routine methodology and there is some concern regarding the potential for monitoring requirements if the standards are placed on specific streams.  This concern should be alleviated by Section 3.1.14(5) of the Basic Regulations but there is uncertainty regarding the interpretation of those numbers by other entities.  Regardless of these concerns, because these constituents are highly toxic, there is a need for regulating their presence in State waters.  Because the Commission has determined that they have uniform applicability here, their inclusion as basic standards for the region accomplishes this purpose. 
5. 	In many cases, the numeric water quality standards are taken from the “Tables” appended to the Basic Regulations.  These table values are used where actual ambient water quality data in a segment indicates that the existing quality is substantially equivalent to, or better than, the corresponding table values.  This has been done because the table values are adequate to protect the classified uses. 
Consistent with the Basic Regulations, the Commission has not assumed that the table values have presumptive validity or applicability.  This accounts for the extensive data in the record on ambient water quality.  However, the Commission has found that the table values are generally sufficient to protect the use classifications.  Therefore, they have been applied in the situations outlined in the preceeding paragraph as well as in those cases where there is insufficient data in the record to justify the establishment of different standards.  The documentary evidence forming the basis for the table values is included in the record. 
6. 	In many cases, instream ambient water quality provides the basis for the water quality standards (See 7 below).  In those cases where the classified uses presently exist or have a reasonable potential to exist despite the fact that instream data reflects ambient conditions of lower water quality than the table values, instream values have been used.  In these cases, the evidence indicates that instream values are adequate to protect the uses.  In those cases where temporary modifications are appropriate, instream values are generally reflected in the temporary modification and table values are reflected in the corresponding water quality standard.  (Goals are established for the appropriate classification affected by the parameter). 
Cases in which water quality standards reflect these instream values usually involve the metal parameters.  On many stream segments elevated levels of metals are present due to natural or unknown causes, as well as mine seepage from inactive or abandoned mines.  These sources are difficult to identify and impractical or impossible to control.  The classified aquatic life uses may be impacted and/or may have adjusted to the condition.  In either case, the water quality standards are deemed sufficient to protect the uses that are present. 
7. 	In those cases where there was no data for a particular segment, or where the data consists of only a few samples for a limited range of parameters, “table values” were generally recommended.  Data at the nearest downstream point was used to support this conclusion.  In some cases, where the limited data indicated a problem existed, additional data was collected to expand the data base.  Additionally, where there may not be existing data on present stream quality, the Commission anticipates that if necessary, additional data will be collected prior to an economic reasonableness hearing required by C.R.S. 1973, 25-8-204(3), as amended. 
8. 	In most cases in establishing standards based on instream ambient water quality, a calculation is made based upon the mean (average) plus one standard deviation (x + s) for all sampling points on a particular stream segment.  Since a standard deviation is not added to the water quality standard for purposes of determining the compliance with the standard, this is a fair method as applied to discharges. 
Levels that were determined to be below the detectable limits of the sampling methodology employed were averaged in as zero rather that at the detectable limit.  This moves the mean down but since zero is also used when calculating wasteload allocations, this method is not unfair to dischargers. 
Metals present in water samples may be tied up in suspended solids when the water is present in the stream.  In this form they are not “available” to fish and may not be detrimental to aquatic life.  Because the data of record does not distinguish as to availability, some deviation from table values, and the use of x + s, is further justified because it is unlikely that the total value in all samples analyzed is in available form. 
A number of different statistical methodologies could have been used where ambient water quality data dictates the standards.  All of them have both advantages and disadvantages.  It is recognized that the x + s methodology also has weaknesses, in that the standard may not reflect natural conditions in a stream 100 per cent of the time, even though the use of x + s already allows for some seasonal variability.  However, the use of this methodology is justified since it provides a meaningful index of stream quality for setting stream standards. 
Since the x + s methodology is an index of existing conditions and is not a classical statistical description, use of a methodology which eliminates outlyers, i.e. unusually high or low data which may be in error, is acceptable in approximating an average condition.  The practice of eliminating only extremely high recorded data points and not low recorded values may result in erring on the side of safety.  High recorded values may be due to sampling, laboratory, or recording error.  To a limited degree the high values may be due to seasonal variation in the data base. 
Finally, the fairness and consistency of the use of any methodology in setting standards must recognize the manner in which the standards are implemented and enforced.  It is essential that there be consistency between standard setting and the manner in which attainment or non-attainment of the standards is established based on future stream monitoring data.  In addition the Division must take this methodology into account in writing and enforcing discharge permits. 
9. 	No water quality standards are set below detectable limits for any parameter, although certain parameters may not be detectable at the limit of the standards using routine methodology.  However, it must be noted that stream monitoring, as opposed to effluent monitoring, is generally not the responsibility of the dischargers but of the State.  Furthermore, the purpose of the standards is to protect the classified uses and some inconvenience and expense as to monitoring is therefore justifiable. 
Section 3.1.15(5) of the Basic Regulations states that “dischargers will not be required to regularly monitor for any parameters that are not identified by the Division as being of concern”.  Generally, there is no requirement for monitoring unless a parameter is in the effluent guidelines for the relevant industry, or is deemed to be a problem as to a specific discharge. 
Some of the data developed by AMAX for metals values were based on “direct aspiration” testing method.  This testing method has a detection limit 100 times higher than the furnace method used by the Division.  In using “direct aspiration”, detection limit is above some of the proposed metal values.  Therefore, the Commission chose to disregard this data.  Because water quality standards are set at levels of ten times below detection limits of the direct aspiration testing method, it is appropriate to use data based upon detection limits of the Health Department Laboratory.  These detection limits for establishing water quality standards may be more restrictive than EPA detection limits for effluent monitoring. 
10. 	The dissolved oxygen standard is intended to apply to the epilimnion and metalimnion strata of lakes and reservoirs.  Respiration by aerobic micro-organisms, as organic matter is consumed, is the primary cause of a natural decrease in dissolved oxygen and anaerobic conditions in the hypolimnion.  Therefore, this stratum is exempt from the dissolved oxygen standard. 
11. 	Where numeric standards are established based on historic instream water quality data at the level of x + s, it is recognized by the Commission that measured instream parameter levels might exceed the standard approximately 15 percent of the time. 
12. 	It is the Commission’s intention that the Division implement and enforce all water quality standards consistent with the manner in which they have been established. 
13. 	Hardness/Alkalinity
Where hardness and alkalinity numbers differed, the Commission elected to use alkalinity as the controlling parameter, in order to be consistent with other river basins and because testimony from the Division staff indicated that in most cases alkalinity has a greater effect on toxic form of metals than does hardness. 
VI. 	Water Quality Standards for Unionized Ammonia
The Commission retains the use of unionized ammonia as a parameter rather than total ammonia because unionized ammonia is the toxic portion.  Furthermore, the relationship of total ammonia as a function of temperature and pH is recognized. 
On some Class 2 Warm Water Aquatic Life streams containing similar aquatic life communities to those found in the plains streams of the South Platte & Arkansas Basins, .1 mg/l ammonia was selected as being appropriate to protect such aquatic life. 
The Commission has relaxed unionized ammonia standards to .1 mg/l or greater on several streams for the following reasons: 
1. 	limited nature of the aquatic life present; 
2. 	limited recreational value of species present; 
3. 	habitat limitations, primarily flow and streambed characteristics, that impose significant limitations on the nature of aquatic life, even if ammonia reductions were attained; 
4. 	rapid dissipation of ammonia in streams, reducing the impact of such discharges downstream; and 
5. 	economic costs of ammonia removal, especially where such costs would fall primarily on publicly-owned treatment works, and while the availability of construction grant funds is questionable. 
6. 	Biosurveys with support from a bioassay conducted on fathead minnows performed in the Cache la Poudre River show that a .1 mg/l standard is appropriate to protect existing biota in that stream.  The results of these studies may be reasonably extrapolated to similar streams; i.e., those streams that demonstrate similar chemical, physical, and biological characteristics. 
Not all warmwater streams are comparable in terms of flow and habitat, and types and numbers of species of aquatic life.  Therefore, some variations in an appropriate ammonia standard must be tolerated, with the objective of protecting existing aquatic life.  The Commission found this approach preferable to totally removing the aquatic life classification from impacted or marginal aquatic life streams. 
VII. 	Water Quality Standards for Uranium
Given the threat that radioactivity from uranium may pose to human health, it is advisable to limit uranium concentrations in streams to the maximum extent practicable.  For segments assigned a water supply classification the Commission has adopted a standard of 40 pCi/l or natural background where higher, for the following reasons: 
1. 	40 pCi/l generally reflects background concentrations of uranium that may be found in streams in Colorado and therefore this amount approximates routine human exposure. 
2. 	The statistical risk of human health hazards is small at 40 pCi/l. 
3. 	40 pCi/l is an interim level, established now pending the outcome of further studies currently underway. 
VIII. 	Water Quality Standards for Cyanide
The Commission acknowledges that total cyanide is to be used in State Discharge Permits until a method is authorized by EPA for measuring free cyanide, even though free cyanide is the parameter of concern. 
IX. 	Water Quality Standards for Metals
Several parties were concerned about the methods that were employed to digest samples used to determine ambient metal values.  The Commission heard testimony that when high suspended solids are present, the two methods of sample digestion could result in very different values, with the “total” method yielding the higher values.  But when the suspended solids are low, the two digestion methods will result in similar values,  Therefor, the Commission has incorporated data generated by the “total” method when it could be determined that the suspended solids in the water sample were low. 
The Commission believes that the “total recoverable” or equivalent method should be used as a testing method for determining ambient metal values for streams.  This method is a better indicator in determining the amount of metal available to aquatic life in a toxic form, particularly when the amount of suspended solids carried by the stream is high.  However, with low suspended solids the two testing methods should yield the same result.  Therefore, before incorporating into stream standards data generated by the “total” method it must be verified that there are low suspended solids in the water samples tested.   
The United States Geological Survey used the “total” method before 1978 and the “total recoverable” after 1978, and that because of this, there might be some inconsistency in the STORET data.  The Commission believes that with the proper check on suspended solids, pre-1976 STORET data can be used to determine ambient stream values. 
It was suggested by AMAX that since the “total” method is used in monitoring state discharge permits, then the “total” method should be used in setting stream standards.  The Commission does not agree.  For the reasons already stated, the Commission believes that the “total recoverable “ is preferable for assigning water quality standards.  And, since most state discharge permits limit suspended solids to 30 mg/l, effluent testing will be similar to the methods underlying stream standards. 
X. 	Linkage of classifications and Standards
The Commission holds that the classifications which it adopts and the standards it assigns to them are linked.  Disapproval by EPA of the standards may require reexamination by the Commission of the appropriateness of its original classification.  The reason for the linkage is that the Commission recognizes that there is a wide variability in the types of aquatic life in Colorado streams which require different levels of protection.  Therefore, the numbers were chosen in some cases on a site specific basis to protect the species existing in that segment.  If any reclassification is deemed a downgrading, then it will be based upon the grounds that the original classification was in error. 
XI. 	Economic Reasonableness
The Commission finds that these use classifications and water quality standards are economically reasonable.  The Commission solicited and considered evidence of the economic impacts of these regulations.  This evaluation necessarily involved a case-by-case consideration of such impacts, and reference is made to the fiscal impact statement for this analysis.  Generally, a judgment was made as to whether the benefits in terms of improving water quality justified the costs of increased treatment.  In the absence of evidence on economic impacts for a specific segment, the Commission concluded that the regulations impose no unreasonable economic burden. 
XII. 	Classifications and Standards - Special Cases
1. 	Page 1, Segment 6(a), 6(b), and 6(c) (Proposed as page 1, segment 6) 
Segment 6(a) receives a discharge from the Roaring Judy fish hatchery.  6(a) contains the tributaries to the mainstem which are intermittent.  The perennial tributaries to the mainstem are included in segment 6(b).  The Commission found no evidence of water supply use associated with segment 6(b) which contains fisheries. 
2. 	Page 2, Segments 7 and 8
Water supply was retained for both segments because segment 8 is subject to conditional water rights held by the Town of Crested Butte.  The agriculture classification was retained because the use it currently in place. 
3. 	Page 2, Segment 9
Segment 9 represents the mainstem of the Slate River from the point immediately above its confluence with Coal Creek to its confluence with the East River.  The Division’s initial proposal was based on 17 samples taken during 1979 through 1981.  These data were significantly influenced by heavy metals entering the Slate River from Coal Creek.  In May of 1981 Amax commenced operation of the wastewater treatment facility treating discharges to Coal Creek, a tributary of the Slate River.  By July, 1981 steady state operation had been achieved.  In view of the significant change in ambient water quality resulting from the operation of the wastewater treatment plant, the Commission adopted the Division’s suggestion that the record on this segment be kept open to receive more meaningful data.  The water quality standards adopted by the Commission are based on combined Amax and Storet data during the period of record July, 1981 through June, 1982.  The water quality standards adopted for this segment are table values from the 0-100 hardness/alkalinity column, with the exception of cadmium, copper, lead and zinc.  The standards for these parameters were based on x + s values derived from the combined Amex and Storet data for the twelve month period of record.  The Storet data was in terms of total recoverable while Amax data was in terms of total metals.  The cadmium level of 0.03 mg/l taken on November 12, 1981 was discarded as an outlier.  All Amax data used had total suspended solids of less than 30 milligrams per liter.  The monitoring location for Segment 9 was at the wooden bridge on Highway 135, 0.25 miles below the Crested Butte domestic wastewater treatment plant. 
Adoption of an aquatic life, class 1 classification with a 0.02 mg/l unionized ammonia standard presents the potential for economic impact upon the Town of Crested Butte.  The Commission acknowledged the potential, for requirements necessitating nitrification facilities but found it justified for the following reasons:  (1) There is no clear and present threat of immediate economic impact; (2) Future impact, if ammonia removal becomes necessary, will be spread among a substantial population base and thus per capita impact will be small; (3) Several interim options are available to the district to further postpone and reduce the probability of significant economic impact; and (4) The Town testified that it was willing to assume the potential for economic impact in order to protect the quality of this segment as it provides a significant contribution to the local recreational resources which account for a substantial portion of the economic base in the region. 
In view of the factors that mitigate the near-term potential for economic impact and since the most likely impacted entity supports this classification, the Commission finds that the assignment of a class 1 designation is economically reasonable. 
4. 	Page 2, Segment 10
This segment receives effluent from the Crested Butte Water and Sanitation District by way of Woods Creek.  Existing aquatic life supports a class 1 cold water classification.  A report by Camp, Dresser, and McKee describes a less expensive alternative to ammonia removal which could be implemented ammonia as an interim treatment to greatly delay the necessity of nitrification facilities.  The Commission acknowledges that removal will probably be required for the Crested Butte W & S District’s wastewater treatment plant as they reach the maximum population in their masterplan.  Ammonia removal maybe required in the near future, but a report by Camp, Dresser, & McKee describes a less expensive alternative which could be implemented.  Notwithstanding such improvements, ammonia removal may be required to provide services for the maximum population projected in the master plan.  The Commission believes that the cost of ammonia removal when it is ultimately required is economically reasonable because of the large population base which will be available to support this requirement and the economic importance of recreational fisheries to communities in this area. 
5. 	Page 3, Segment 12
In the initial proposal, Segment 12 included the mainstem of Coal Creek from a point immediately above the confluence with Elk Creek to a point immediately below the Crested Butte water supply intake.  Elk Creek and its tributaries were added to this segment since water quality sampling indicated that the water quality of Elk Creek and Coal Creek are similar.  Although a recreation class 2 was adopted for this segment a fecal coliform standard of 200 per 100 m/l was adopted by agreement of the interested parties and because the standards is currently met. 
6. 	Page 3, Segment 13
The Division’s initial proposal for this segment was based on four samples taken prior to the startup of the Amax wastewater treatment facility in July of 1981.  This facility treats the discharge from the inactive Keystone Mine which is the principal point source discharger into Coal Creek.  In view of the significant change in ambient water quality resulting from operation of the wastewater treatment plant, the Commission in effect adopted the Division’s suggestion that the record on this segment be kept open to receive more meaningful data.  The aquatic life cold water class 1 use classification for this segment is based on ambient flow (Q7-10 = 3.5 CFS), quality conditions with continuous operation of the Amax wastewater treatment facility, and presence of aquatic life.  These standards include consideration of the existing discharge and it is not anticipated that additional treatment will be required.  Where water quality data was available, the water quality standards adopted for this segment were developed based upon the ambient flow conditions and water quality in this segment for those parameters.  Only cadmium and zinc were greater than table values in the 100-200 hardness/alkalinity range.  If Crested Butte fully exercised its decreed water right in Segment 12, the flow in Segment 13 would essentially be the discharge from the Amax wastewater treatment facility.  This flow is in the greater than 400 hardness/alkalinity range.  If, changes in flow conditions occur or if data subsequently becomes available for water quality standards based on table values, these water quality standards should be reviewed for compatibility with ambient conditions.  The water quality standards for cadmium and zinc are x + s values based on Amax data for the twelve month period of record of July, 1981 through June, 1982.  This data is in terms of total metals.  However, all data had suspended solids of less than 30 milligrams per liter.  The November 12, 1981 samples for zinc, iron and manganese were determined to be outliers.  The monitoring location for Segment 13 was on Coal Creek 30 meters upstream from its confluence with the Slate River and the water quality standards are specific to this location.   
7. 	Page 3, Segment 14
An aquatic life classification has not been assigned to this segment because the presence of aquatic life is extremely limited, flow is intermittent, gradient is steep, and fish habitat is not present.  The potential economic impact of standards to protect an aquatic life classification is therefore not justified. 
8. 	Page 3, Segment 15
Water Supply and agriculture are existing uses.  An aquatic life, class 1 classification may require occasional ammonia removal.  The City of Gunnison supported aquatic life, class 1 classification. 
9. 	Page 4, Segment 17
The Division’s initial proposal for water quality standards for segment 17 was based on table values from 0-100 hardness/alkalinity column.  The standards adopted are the same with the exception of zinc which represents the x + s of the Amax data for the period of record.  The Amax data was in terms of total metals.  However, all data used had total suspended solids of less than 30 milligrams per liter. 
10. 	Page 4, Segments 21(a) 21(b) and 22
Indian Creek has been resegmented into 2 segments, 21(a) and 21(b), to reflect variability’s in water quality and aquatic life. 
The uranium standard of 2.0 mg/l for Segment 21(a) is sufficient to protect the aquat65ic life in that segment.  The standard is consistent with historic instream conditions and the existing discharge at SW33.  The determination that this standard is sufficient to protect aquatic life is based upon bioassay and benthic studies which are included in the record (Homestake additional Exhibit A, Vol. II, pp. 232-235 and Homestake Exhibits H-N).  This standard will adequately protect the classified uses assigned in Segment 21(b), and in Segment 22, Lower Marshall Creek.   
The uranium standard of .3 mg/l for Segment 21(b) is sufficient to protect the aquatic life in that segment.  The more stringent standard adopted here is consistent with historic instream conditions based upon data taken at both monitoring stations within the segment, namely SW3 and WQCD 149.  The Division, in implementing and enforcing the standard for Segment 21(b), should recognize this fact that the standard reflects data from both stations.  SW3 is located on Indian Creek approximately 660 feet below the confluence of Indian Creek and Bull Creek, and Station 149 is located in close proximity to Homestake sampling station SW4.  The standard for segment 21(b) will adequately protect the classified uses assigned in segment 22, including the water supply use that exists there.  It should be noted that there is not water supply use in either segment 21(a) or segment 21(b). 
11. 	Page 6, Segments 29, 30, 31, and 33
A U.S. Forest Service letter dated December 9, 1981, provided water quality data for streams on segments 29, 30, 31, and 33 of the Upper Gunnison.  It was considered unreliable because the reported concentrations were too hi9gh to support aquatic life on streams acknowledged by the U.S. Forest Service as good fisheries. 
12. 	Page 7, Segment 5; North Fork of the Gunnison 
Hubbard Creek was not separated from this segment as requested by the Blue Ribbon Coal Company as the presence of three species of trout justifies a class 1 aquatic life classification.  The water supply use is also in place and the evidence indicated that uses in Hubbard Creek were compatible with the balance of the segment.  In addition, although the Blue River Coal Company is a NPDES discharge permit holder there is currently no discharge and no current economic impact. 
13. 	Page 9, Segment 5 
An aquatic life classification of cold water, class 1 was requested for Wehauken Creek to protect an existing private trout hatchery on the creek.  However, the majority of the tributary streams in this segment do not support fisheries because of steep gradients.  The Commission elected to classify the segment as aquatic, cold water, class 2 with table values for cold water, class 1 to protect the fish hatchery on Wehauken Creek. 
14. 	Page 9, Segment 6 
The aquatic life classification was removed because the Commission found no evidence of aquatic life in this segment and determined that there was no expectation of such use in the future.  The segment is badly degraded by mine drainage. 
15. 	Page 12, Segment 2 
The Commission assigned the segment a cold water, class 1, aquatic life classification having found: That the City of Delta would not be adversely impacted due to the dilution provided by large stream flows. 
16. 	Page 14, Segment 5 
An underlying standard for ammonia of .08 mg/l was adopted based upon the results of a bioassay conducted in 1975.  Although this represents a relaxation of the proposed standard of .06 mg/l, this result is justified since the bioassay reflects site specific conditions for pH, temperature and TDS, which factors affect ammonia toxicity. 
The temporary modification for ammonia reflects seasonal variations in ammonia levels based upon existing discharge permit conditions.  Since the existing discharge will cease in 1986, the conditions causing exceedence of the underlying standard will be corrected within a 20 year period  These facilities will be replaced by new facilities designed for zero discharge of ammonia.  In view of the cost of the new facilities and the limited duration of the existing discharge, a standard necessitating additional interim treatment facilities would not be economically reasonable. 
COLORADO DEPARTMENT OF HEALTH
Water Quality Control Division 
4210 East 11th Avenue 
Denver, Colorado  80220 
F I S C A L   I M P A C T   S T A T E M E N T
Stream Classifications and Water Quality Standards for State Waters of the Lower Colorado Basin below Glenwood Springs; the Yampa River Basin below Elkhead Creek; the Green river; and the entire White River drainage including all tributaries and standing bodies of water associated with those rivers in all of Moffat, Rio Blanco, Garfield, and portions of Mesa and Routt Counties. 
I. 	INTRODUCTION
The Water Quality Control Commission is charged with he responsibility to conserve, protect, and improve the quality of state waters pursuant to C.R.S. 1973, 25-8-101 et seq. 
The Commission is further empowered and directed to classify waters of the State and to promulgate water quality standards for any measurable characteristic of the water in order to protect both the uses in place and those that can be reasonably expected in the future.  (25-8-203 and 25-8-204)  The above-titled document assigns use classifications and standards for the state waters in the listed areas in accordance with the “basic regulations” adopted May 22, 1979. 
The measurable fiscal impacts which may be caused by these regulations are as follows: 
- 	Cost of construction due to requirements for increased levels of treatment by municipal waste treatment facilities; 
- 	Cost of construction due to requirements for increased levels of treatment by industrial/commercial waste treatment facilities; 
- 	Cost of Operation and Maintenance associated with increased levels of treatment required of municipalities; 
- 	Cost of Operation and Maintenance associated with increased levels of treatment required of industrial and commercial dischargers; 
- 	Cost of instream monitoring and laboratory analysis for new parameters added by the standards. 
Dischargers will not be required by the adoption of these regulations to do stream monitoring.  The state, federal and local agencies now doing instream monitoring will have some increased cost; however, any additional frequency should be done to improve state surveillance and would be needed regardless of standard changes. 
The stream classifications and standards adopted by the Commission will protect the water uses primarily through control of point source pollution.  Non-point source pollution will be controlled primarily through management practices which are in existence or which will be implemented in the future.  Future management practices need careful consideration and may be the result of 208 area-wide wastewater management plans developed by regional planning agencies and being updated annually.  These plans involve local governments with general assistance from state government.  Some of the possible non-point source pollution may be controlled through “Control Regulations” yet to be promulgated by the Commission.  These types of controls could involve runoff from construction, mining activities, and urban areas.  It is not certain what controls are needed at this time and there is no way that possible costs can be identified at this time 
Persons who benefit from standards which will protect existing and future anticipated uses can be identified as all persons benefiting from recreation, municipal water supply, and agriculture.  These benefits are directly economic for agriculture, industry, and municipalities whose health benefit costs are reduced by having clean water, and are both economic and non-quantifiable for some uses such as fishing, recreation, and the aesthetic value of clean waters.  Furthermore, benefits will result from human health protection and lack of debilitating disease.  Figures have been developed for a recreation/fishing day which can be applied to that aspect of a water use’; however, figures which have been developed for total recreation/fishing day uses have been developed statewide and could not be applied region-by-region or stream-by-stream. 
The uses of water in this region are adequately protected by these standards.  Most municipal treatment facilities and industrial facilities are currently adequate, or are already being upgraded, in order to meet previous requirements.  Any additional facilities or expansions in this region will generally be caused by increased capacity required because of population growths or industrial enlargement.  Industries are required by federal statute to meet effluent limitations described as “Best Available Technology Economically Achievable” (BATEA) by 1983 or 1984.  For most major industries in this region, the water quality standards should not require treatment beyond these limitations. 
The fiscal impact of any regulatory decision must take into account only the incremental costs explicitly associated with the regulations as finally promulgated.  Costs and expenditures associated with the status quo, regulations of other regulatory agencies, or regulations already in effect should not be included in an assessment of the fiscal impact of the Gunnison River Basin Classifications. 
In addition, a distinction must be made between actual expenditures or dislocations that will be immediately or unavoidable necessary upon promulgation of these classifications and standards, and those costs which are speculative in nature.  In keeping with concepts of ‘Expected Value’, it is proper for the Commission to place more emphasis on definite impacts. 
With the passage in 1981 of Senate Bill 10, amending the Colorado Water Quality Control Act, it becomes incumbent upon the Water Quality Control Commission to consider the economic impact of their decisions with more emphasis placed upon the concept of the “Economic Reasonableness”.  Charged with such a mandate, the Commission was quite sensitive to the objective of minimizing the socio-economic “price” of clean water while adhering to the anti-degradation policy that water quality be preserved and protected in all cases, and improved wherever feasible.  The Gunnison River Basin was heard under the provisions of the Act. 
The analysis and data which follow are derived primarily from testimony and exhibits offered by interested parties during the course of the rulemaking hearings.  This was supplemented by staff assessments of potential impacts upon other major entities who were not formally represented.  The impacts are separately presented for the public and private sectors.  No attempt has been made to identify future development costs as this type of data is not readily available and estimation techniques are dependent upon many highly subjective assumptions. 
II. 	FISCAL IMPACT:  PUBLIC SECTOR
The primary fiscal impact to the public sector in this basin involves the potential domestic wastewater treatment costs associated with the stream classifications and water quality standards.  Other costs, such as tax and employment base impacts due to forgone industrial development opportunities or mitigated growth potentials, can be theoretically postulated but are difficult to quantify.  Generally, it is recognized that higher tap fees, service charges or property taxes associated with increased treatment costs can potentially affect industrial siting decisions.  However, this is not as significant as increased levels of treatment that may be required of industries if they are dischargers.  While the Commission acknowledges the existence of such potentials, the lack of firm evidence and actual tax base impact estimates make deliberative assessment impractical. 
In this basin the Commission acknowledged four municipalities that may be impacted:  Crested Butter Water and Sanitation District, The Town of Crested Butte, Delta, and The Gunnison Water and Sanitation District.  In each case the standard for unionized ammonia was the factor of concern. 
The Commission recognizes the probability of increased treatment costs to accrue to the town of Crested Butte to meet the ammonia standard but fund these costs to bear a reasonable relationship to the benefits to be derived.  The essential rationale is the support for these standards by the Town of Crested Butte in order to maintain the lucrative tourism industry through preservation of premium fisheries.  Crested Butte went on record to state that they felt the economic benefits would outweigh the costs to achieve them.  In addition, the Commission finds that’s:  (1) There is no immediate potential for economic impact; (2) future economic impact, if nitrification becomes necessary, will be spread among a substantial population base thereby minimizing per capita burden; (3) several interim options are available to the City to postpone and reduce the probability of economic impact as detailed in the East River Valley Wastewater Facilities Plan prepared by Camp, Dresser & McKee which was submitted to the Commission as additional information; and (4 as evidenced by the plan, the City is planning and preparing for a twenty-year program to include nitrification facilities and is aware of the economic requirements to support the plan. 
The Crested Butte Water and Sanitation District will most likely need ammonia removal as they  approach the maximum population in their masterplan.  As estimated for 1982 in the facilities plan, nitrification facilities will cost 1.168 million dollars.  The Commission has determined this cost to be economically reasonable for many of the same reasons as for the Town of Crested Butte.  The District and the Town ill most likely share in the costs of the facilities and thus there will be a large population base to support ammonia removal costs.  Finally, the District’s economic base is largely derived from the tourism and recreation industry of which the value is strongly related to the quality of the fisheries in the region. 
The Town of Delta is recognized as facing a potential requirement for nitrification facilities but several mitigating factors lead the Commission to conclude that this potential was negligible.  The Town offered testimony indicating that they felt there would be no foreseeable impact and they are in the process of converting to a rotating biological disc (RBD) system which will lower the ammonia in their effluent.  The Commission noted that Delta’s discharge into the Gunnison River is at a point of high volume (Q710=210 CFS) and a wide channel which, in addition to a high dilution factor, leaves room for options such as mixing zones.  Coupled with these factors, the Commission believes that provisions contained in the Colorado Water Quality Control Act as relating to advanced wastewater treatment requirements adequately protect the Town from any remaining potential for economic impact through the provisions of Section 204(3), C.R.S. 1973. 
In the case of the Gunnison Water and Sanitation District, the District supports a class 1 cold water designation recognizing that there could be some economic impact.  The District is strongly supported by the economic base of tourism and recreation of which excellent fisheries is important.  Because of the District’s support of the classification and thus their implicit willingness to accept the economic impact that could result, the Commission is compelled to conclude that the potential for economic impact bears a reasonable relationship to the benefits to be derived from the ammonia standard. 
In summary, the public participation and careful deliberation have resulted in regulations that will protect the quality of the waters of the Gunnison River Basin through classifications and standards that are economically reasonable in terms of the costs to the municipalities lying with the region. 
It must be noted that before advanced treatment can be required and the costs discussed herein incurred, a hearing is available pursuant to section 204(3), C.R.S. 1973. 
III.	FISCAL IMPACT:  PRIVATE SECTION 
Six private sector entities were identified concerning potential economic impacts as a result of the proposed standards in this basin:  Homestake Mining Company, Blue Ribbon Coal Company, ARCO, the Idarado Mine, Union Carbide, and AMAX.  All of these entities have been, are, or will be involved in mining and milling activities with the region. 
The Homestake concern was with uranium limits.  They indicated that they would be forced into a zero discharge situation if the standard for Indian Creek remained as proposed.  This posed the potential of shutting down their operation entirely with the resultant loss of jobs and economic contribution to the region.  The beneficial uses for the relatively short segment length for which Homestake claimed difficulty in meeting the standard were found to not bear a reasonable relationship to the economic consequences of the uranium standard.  Thus the Commission adopted a proposal for resegmenting Indian Creek to accommodate both Homestake’s concerns and the beneficial uses to be preserved by the uranium standard.  This action was found to not significantly impact the beneficial uses of the stream while eliminating the potential economic cost of the proposed segmentation. 
Blue Ribbon Coal Company was concerned with the accuracy of the proposal for Hubbard Creek.  They do not currently, nor plan to, discharge into this segment and indicated no specific economic cost to be attributed to the proposed classifications.  Because the Commission found the evidence to be supportive of the proposed classification, and because no specific economic consequences were in evidence to mitigate the benefits of the proposed classification, the Commission found the most economically reasonable position was to support the classification of Hubbard Creek as proposed. 
ARCO was primarily concerned with the accuracy of the classifications and was interested in the controversy surrounding the different techniques for measuring the presence and concentration of heavy metals.  No specific evidence was offered indicating economic costs to be associated with these standards.  Because the Commission found compelling evidence to support the protection of beneficial uses through the proposed classifications and that there were no offsetting economic consequences, the most economically reasonable course of action was to retain the proposal. 
The Idarado Mine (“project”) currently is not in active operation but is permitted to discharge into the San Miguel River for which Cold Water, Class 1 Aquatic Life was retained as a classification.  The Commission found this classification to the reasonable in respect to the Idarado Project for several reasons:  one, the future of the project is uncertain both to its economic viability and whether and when it will start active operations; two, no specific economic impact evidence was offered to measure against the beneficial uses of the San Miguel as a fishery; and three, the Idarado Project has available to it the option of discharging into Red Mountain Creek which was found to be so severely impacted by past and current human activities that no metals numbers were assigned as standards and virtually no beneficial uses were in evidence to be protected.  The Commission found this to be the most economically reasonable manner in which to deal with the concerns of the Idarado project. 
Union Carbide indicated a potentially wasteful economic impact that would result from the ammonia standard proposed for the mainstem of the San Miguel River.  They testified that they use ammonia to stabilize the pH of their process water and that while they could meet the standard for part of the year with their current operational scheme, they could not meet the standard on a year-round basis.  Union Carbide stated that they are currently planning a treatment facility that would be of the no-discharge type at an estimated installed capital cost of around thirty million dollars but this facility would not be on line until sometime in 1986.  Thus, if the standard was retained, they would be forced to build facilities in incorporate other pH stabilizing techniques in the interim at an installed capital cost of between $730,000 and $1, 000,000 with an annual operating cost of approximately $200,000.  The Commission adopted a seasonal temporary modification until such time as the no-discharge facility will be operational.  In light of the fact that the interim facility would be rendered useless after four years, the Commission found that cost to not be reasonable.  The seasonal standard was adopted as economically reasonable since any exceedances of the underlying standards will be corrected when the no-discharge facility is operational and no permanent, uncorrectable damage to the fishery would result.  
AMAX was concerned with issues relating to the procedures and methodology used to develop the proposals.  They believed that the standards could result in treatment costs approaching several hundred million dollars assuming that technology was available which they content most likely is not.  To avoid this potential, AMAX offered seasonal standards which they felt were more reflective of the ambient qualities of the mainstem of Ohio Creek.  The Commission decided to keep the record open to allow the Division as well as AMAX to pool additional data for both Coal Creek and Ohio Creek in order to test AMAX’s claim that their additional data and a change in the hardness/alkalinity would alter the standards and thus the potential for debilitating economic impact.  The additional data from AMAX was folded into the Division’s calculations and most of the metals of concern did evidence higher ambient levels.  The standards were changed to reflect these higher levels.  The Commission found these amended standards to be acceptable on economic terms because no clear and present threat of economic impact was in evidence and they there are administrative options available to consider future impact if they develop. 
Through evaluation of expert testimony and careful deliberative consideration, the Commission has taken steps to minimize the economic impact of these classifications and standards upon the private sector.  As adopted, these classifications and standards will have a negligible impact upon the private sector while protecting current and achievable beneficial uses. 
It is concluded that the Commission has strenuously considered the economic factors at issue in this basin and that this regulation is economically reasonable both in terms of potential costs that may result, and in terms of the beneficial uses to be protected. 
35.12 	STATEMENT OF BASIS AND PURPOSE REGARDING THE ADOPTION OF MINOR CORRECTONS AND CLARIFICATIONS FOR THE BASIC STANDARDS AND METHODOLOGIES AND CORRECTIONS TO THE NUMERIC STANDARDS FOR THE SAN JUAN AND DOLORES, GUNNISON, AND LOWER DOLORES, RIO GRANDE, AND THE SOUTH PLATTE RIVER BASINS. 
BASIS AND PURPOSE: 
In accordance with the requirements of 24-4-103(4), C.R.S. 1973, the Commission makes these findings and adopts this Statement of Basis and Purpose.  The Commission at a public rulemaking hearing November 14, 1983, and December 12, 1983, adopted minor and editorial corrections to clarify the Commission’s current regulations numbered respectively 3.1.0, 3.4.0, 3.5.0, 3.6.0, and 3.8.0.  These regulations are contained in Article 3, Water Quality Standards and Classifications, of the Policies, Regulations, and Guidelines of the Water quality Control Commission.  (5 CCR 1002-8)  
In adopting these corrections and clarifications, the Commission considered the economic reasonableness of its action.  The scientific or technological rationale of the Commission in justifying the changes to its rules was that it made the classifications and standards which it had previously assigned more technically correct and accurate. 
The consolidated changes adopted by the Commission are provided with this Basis and Purpose.  The Secretary of State is being provided corrected pages for each of the regulations as replacements for pages previously published in those regulations. 
An issue raised during the hearing, was whether or not the table or organic parameters should be moved from the Appendix to the text.  The Commission included standards for organic parameters in the regulations it adopted for each of the River Basins of the State.  Thus, standards for organic parameters were applicable Statewide, prior to the hearing to consider the changes to which this Statement of Basis and Purpose is applicable.  This has had the same effect as would have a basic standard applicable to all waters of the state. 
The Commission finds that it would be easier to make changes to one document, the Basic Standards and Methodologies, as future scientific information necessitates, than to make such changes in each basin.  Thus it is more economically reasonable to deal with the organic substances in one regulatory document, rather than many.  There was testimony that it was confusing to have the table of organic parameters as criteria guidance subject to change on a stream by stream basis when the parameters had been assigned and were merely to provide guidance.  It was testified that it would be less confusing to have the table in the text of the regulation to provide basic standards. 
The City of Loveland testified that if the table in question were move to the regulatory text there was the possibility of a basin standard differing from the general standard.  The Commission found that its regulations enabled I to set site specific standards to stream segments as an exception to the basic standard, and that for the parameters in this table it was unlikely to have different basin standards. 
The organic parameters in the table are not substances that form a naturally occurring background.  They are toxics controlled at the point of sale or use.  They are not ambient and subject to the same treatment as are other naturally occurring parameters.  The Commission found it inappropriate to regulate these organic constituents in the same manner as are those that can be ambient or uncontrollable background parameters.  Therefore, the Commission changed the guideline table to a basic standard in the body of the regulation. 
35.13 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY, AND PURPOSE:
The provisions of 25-8-202(1)(a) (b) and (2); 25-8-203; and 25-8-204, C.R.S., provide the specific statutory authority for consideration of the attached regulatory amendments and also the statements of Basis and Purpose and Fiscal Impact in compliance with 24-4-103(4) C.R.S. 
BASIS AND PURPOSE: 
At the triennial review conducted April 7, 1986, no recommendations were received from the public.  Non-substantive amendments were recommended by the Water Quality Control Commission to correct clerical errors.  In adopting these corrections, the Commission considered the economic reasonableness of its action.  Except as specified, the corrections in no way change the classifications and numeric standards originally adopted by the Commission. 
FISCAL IMPACT STATEMENT: 
The Water Quality Control Commission found that the clerical corrections to its regulation 3.5.0 have no fiscal impact. 
35.14 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; 1988 AMENDEMENTS REGARDING SAN MIGUEL RIVER SEGMENTS
The provisions of 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-207 C.R.S., provide the specific statutory authority for adoption of the attached regulatory amendments.  The Commission also adopted, in compliance with 24-4-103(4) and 24-4-103(8)(d) C.R.S., the following statements of basis and purpose and fiscal impact. 
BASIS AND PURPOSE: 
The hearing that resulted in these amendments was held as the result of a petition submitted by the Idarado Mining Company (Idarado).  Idarado requested that the Commission, pursuant to 25-8-207 C.R.S., make a finding of inconsistency regarding certain use classifications and water quality standards in effect for the San Miguel River and related tributaries and that those classifications and standards be declared viod ab initio.  Idarado also requested that the Commission establish and adopt revised segment boundaries, use classifications and water quality standards for those waters.  The Idarado proposal was opposed by the Division of Wildlife (DOW), the Town of Telluride, and San Miguel County (who were also parties to the proceeding), and by the Water Quality Control Division (WQCD). 
Idarado owns the Idarado Mine located, in part, approximately one-half mile east of the Town of Telluride, County of San Miguel, Colorado.  That portion of the mine is located in the San Miguel river drainage basin which is a part of the Lower Dolores river Basin (3.5.0) 5 CCR 1002-8. 
The headwaters of the San Miguel River, Formed by the confluence of Bridal Veil and Ingram Creeks, are located approximately one mile east of the Idarado mine and Pandora Mill site.  The San Miguel River then flows past Idarado’s properties, through the town of Telluride, and eventually to the Dolores River several miles downstream. 
Idarado presently discharges water from the mine pursuant to a National Pollutant Discharge Elimination System permit (No. CO-0026956).  Discharges from the mine are to the ground, not directly to surface waters. 
The State of Colorado, in 1983, sued Idarado under the Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (“CERCLA”), 42 U.S.C. & 9601 et seq.  In that action, the State alleges that Idarado’s operations have resulted in injury to the environment.  Idarado has vigorously contested that allegations and that action is presently pending in federal district court.  Much of the information presented in this proceeding originally was generated in connection with the State CERCLA litigation. 
Summary of Action:
Segment 3 of the San Miguel is resegmented into segment 3a above Marshall Creek and segment 3b below.  Marshall Creek and Ingram Creek are divided into separate segments segment 6a for Ingram Creek and segment 6b for Marshall Creek.  The existing classifications are retained for all segments. 
For new segment 3a, the existing numeric standards are retained except that the zinc standard is changed to 0.19 mg/l, a table value standard (for the 0 to 100 hardness range) is adopted for lead, and 6-year for Marshall Creek.  The existing classifications are retained on all segments. 
For new segment 3a, the existing numeric standards are retained except that the zinc standard is changed to 0.19 mg/l, a table value standard (for the 100 to 200 hardness range) is adopted for lead, the table value standard for nickel is revised, based on the new hardness range, and 6-year temporary modifications based on the existing ambient quality are adopted for cadmium, copper, lead and zinc. 
For new segments 6 a and 6b, the existing numeric standards are retained except that the zinc standard is changed to 0.19 mg/l, table value standards (for the 0 to 100 hardness range) are adopted for cadmium, copper, and lead, and 6-year temporary modifications based on the existing ambient quality (except where it is already better than table values) are adopted for cadmium, copper, lead and zinc. 
For the reasons elaborated below and in the Fiscal Impact Statement, the Commission has determined that these changes are economically reasonable.  This is particularly the case since the costs that will be incurred by Idarado to achieve the revised standards are the result of a need to remedy prior impacts caused by Idarado. 
Resegmentation:
The resegmentation of the San Miguel mainstem into segments 3a and 3b is warranted because water quality differs above and below Marshall Creek and significantly different aquatic life habitat is attainable above and below this point.  Because of the influence of Marshall Creek, water quality in the San Miguel is significantly different below their confluence. 
There was evidence that habitat limitations in the mainstem are significantly more pronounced above Bear Creek (downstream of Marshall Creek) due in part to rechannelization as the result of Idarado’s operations and due to lower stream flows.  The mainstem has been resegmented at Marshall Creek rather than Bear Creek because there was evidence that habitat limitations on the mainstem between those two creeks are largely correctable. 
The resegmentation of Ingram and Marshall Creeks into segments 6a and 6b is warranted by the significantly different current water quality of those two streams 
Idarado proposed the establishment of additional sub-segments on the San Miguel mainstem and of separate segments for several additional tributaries which currently are grouped together as part of segment 2.  The additional mainstem resegmentation appears unnecessary at this time.  While there is evidence of some variations in water quality and habitat in this stretch, they do not appear substantial enough to warrant further resegmentation.  Also, there is not enough differences to warrant, separate segmentation for the other tributaries.  Moreover, it is not apparent that further resegmentation would have significantly different regulatory impacts on potential affected entities. 
Classifications: 
Retention of the existing classifications is warranted by the evidence submitted.  Marshall Creek and Ingram Creek retain their current cold water aquatic class 2 designation because of the evidence that they currently are, and are likely to remain, habitat-limited.  No parties challenged this classification. 
The other segments at issue retain their current cold water aquatic life class 1 designations.  For the mainstem of the San Miguel, below Bear Creek all parties agreed that the class 1 designation is appropriate.  From Bear Creek upstream to Marshall Creek, there was evidence of some degree of current habitat limitations, as well as water quality limitations on aquatic life.  The Commission believes that any habitat limitations are correctable within a twenty year period. 
For new segment 3a above Marshall Creek, there was some evidence that flows in this stretch are very limited, creating a significant habitat limitation.  However, there was other evidence that there are substantial flows in this segment for significant parts of the year, adequate to support a variety of aquatic life. 
For the other tributaries that were not resegmented or reclassified, there was some evidence that habitat limitations may be a significant factor on these streams, due primarily to flow and gradient conditions.  However, the Commission does not believe this evidence was substantial enough to warrant reclassification.  Moreover, it is not apparent that reclassification of these tributaries would have significantly different regulatory impacts on potentially affected entities. 
Standards:
The revised metals standards for segments 3a, 3b, 6a and 6b have been adopted because the information currently available indicates that the more stringent levels should be attainable within a 20-year period.  All parties agreed that significant improvement in water quality will occur as a result of the changes that will be implemented due to the legal actions that has been instituted under the Comprehensive Environmental Response, compensation and Liability Act (CERCLA).  At a minimum, the cleanup plan proposed by Idarado Mining Company will result in some water quality improvement.  The standards are consistent with levels found to be achievable by the Record of Decision prepared by the State in the CERCLA action. 
The Commission recognizes that the evidence demonstrates some uncertainty as to exactly what water quality levels will be achievable following any cleanup of the site.  However, in view of (1) the evidence submitted, (2) the desirability of establishing specific standards that can serve as a goal for regulatory and planning purposes, and (3) the Water Quality Control Act’s policy of encouraging water quality improvement where feasible, the revised standards are appropriate at this time.  If additional information developed in the future demonstrates that any of these standards are in fact not attainable within a 20-year period, the standards can be revised accordingly. 
For those revised standards based on table values, for segment 3b the values associated with the 100 to 200 hardness range have been used because the data indicates that hardness for this segment typically is in this range.  Although the Commission typically has used alkalinity levels instead of hardness where that would result in more protective standards, harness has been used here because of the greater quantity of hardness data available. 
The Commission also has adopted temporary modifications for the metals for which standards have been revised, based on the current ambient quality, as calculated by the “mean plus one standard deviation: methodology.  The adoption of these temporary modifications recognizes that cleanup of past mining-related impacts and resulting water quality improvement will take time.  Thus, the temporary modifications recognize current conditions, while the revised standards establish goals that should be using for purposes of cleanup and other planning decisions.  The temporary modifications have been adopted for six years because it appears from the evidence that completion of any site cleanup as a result of the CERCLA litigation will take at least that long.  It is anticipated that the need for the temporary modifications would be reviewed in the 1992 triennial review of the Gunnison and Lower Dolores River Basin standards.  At that time, the temporary modifications may be extended if new information then available demonstrates that the underlying standards cannot be attained by the expiration date of the current temporary modifications.  
The Commission rejected the argument by Idarado that permanent standards should be set equal to the existing instream quality.  The Commission Believes that water quality does act as a limiting factor with respect to aquatic life in these segments.  Moreover, as a matter of policy the Commission does not believe that only those aquatic life currently present in these segments warrant protection. 
Summary:
The Commission has determined that the “findings of inconsistency” requested by Idarado pursuant to 25-8-207, C.R.S. is not appropriate.  Use classifications and water quality standards for aquatic life for the segment in question are not more stringent than is necessary to protect fish life, shellfish life, and wildlife in water body segments which are reasonably capable of sustaining such life.  Moreover, use classification and water quality standards were not adopted based upon material assumptions that were ion error or no longer apply.  Based on new developments and new information since the original classification and standard-setting proceeding, the Commission has adopted revisions to stream segmentation and standards, as described above. 
35.15 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY, AND PURPOSE: (1988 revisions regarding Canyon Creek, Sneffels Creek and Imogene Creek) 
The provisions of 25-8-202  (1) (b) and (2); 25-8-204; and 25-8-207 C.R.S. provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted, in compliance with 24-4-103(4), and 24-4-103(8)(d), C.R.S. the following statement of basis and purpose and fiscal impact. 
Basis and Purpose: 
No change in the aquatic use classifications was requested, although aquatic uses are extremely limited in the new segment 9a.  A water supply classification was included for the existing segment 5 within which the headwaters were previously included, and the ambient quality should be sufficient to support that use.  No water supply uses exist or are anticipated in super Imogene and Sneffels Creeks and the existing quality is poorer than the dissolved manganese criterion for a water supply classification.  Therefore, new segments 9a and 9b do not include a water supply use classification. 
The changes in water quality standards are based upon a one-year sampling program conducted by Engineering Science, Inc., in consultation with the Division.  The changes more accurately reflect existing stream quality, since the Commission’s 1983 adoption of classifications and standards for these segments was based upon extremely limited data. 
In determining appropriate standards based on the new data, the Commission applied the Division’s established methodology for the rejection of certain data “outliers”.  The Commission felt that the inclusion of these outliers in the standards calculation would have resulted in standards that are not representative of water quality normally found in the segments in question.  The adopted standards more accurately reflect existing ambient quality. 
The temporary modification for mercury for segment 9b, adopted for one year, is based on the level necessary to protect aquatic life.  The underlying standard for mercury is based on the level necessary to protect human health, assuming bioaccumulation of mercury in fish tissue.  If a bioaccumulation study is completed on this segment by the Camp Bird Venture prior to the expiration of the temporary modification, the Commission will reconsider the appropriateness of the underlying standard. 
The basis for the adoption of the temporary modification for lead in segment 9a is that imposition of the underlying standard at this time would likely result in substantial and widespread economic and social impact within the area in question, without corresponding environmental benefit.  Evidence submitted indicates that construction of a treatment plant to meet the underlying standards could cost on the order of one to two million dollars.  A cost of this magnitude would put continuation of the current exploration activities at the Camp Bird Mine – which currently employees 97 people – at risk. 
The Commission also decided that no permanent downgrading of the segments in question is necessary at this time.  Within the time frame of the temporary modification, the Camp Bird exploration operations would be completed and the long-term economic impact of meeting the underlying standards should be known.  If new information n economic impacts or ambient water quality becomes available prior to that time, those segments can be readdressed at the request of Camp Bird Venture.  In any event, at the next triennial review, the pending revision to the Basic Standards and Methodologies, although it is not anticipated that new facts will be available by that time to warrant reconsideration of the temporary modifications. 
Fiscal Impact: 
Other than the rulemaking hearing, no increased regulatory costs will result from the changes.  No change in existing mine discharge flows is contemplated, and existing treatment of the historic mining flows will continue during the life of the temporary modification for lead.  Adoption of the temporary modification will avoid the potential for an adverse substantial and widespread economic and social impact that could result from requiring immediate compliance with the underlying standards. 
The revised standards, based on more accurate data, generally are less stringent than the previous standards for these waters.  This should help assure that discharge treatment requirements are not unnecessarily string, resulting in potential long-term cost savings for existing or future dischargers. 
35.16 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; May, 1990 HEARING ON SEVERAL SEGMENTS: 
The provisions of 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4), C.R.S., the following statement of basis and purpose. 
Basis and Purpose: 
First, the Commission has adopted new introductory language for the tables in section 3.5.6.  The purpose of this language is to explain the new references to “table value standards” (TV) that are contained in the Tables.  These provisions also include the adoption of new hardness equations for the acute and chronic zinc standards throughout the basin.  Based on information developed since the “Basic Standards” were revised, these new equations have been determined to represent more appropriate zinc criteria.  The other changes considered and adopted are addressed below by segment. 
One other general issue should be addressed at the outset.  Several parties to this proceeding submitted documents expressing concern regarding the adoption of High Quality 2 designations because of potential impact on water rights held by these entities.  Although none of the initial documents submitted specifically asserted that the rulemaking proposal would cause material injury to these entities’ water rights, particula4rly because the Senate Bill 191 consolations process is new, the Commission transmitted these documents to the State Engineer and the Colorado Water Conservation Board to solicit any comments that they might have.  In its transmittal letter, the Commission stated its preliminary assessment that the proposed adoption of High Quality 2 designations did not present the potential to cause material injury to water rights.  
The High Quality designation merely indicates that an antidegradation review will be required for certain activities.  In its regulations, the Commission has specifically provided that in an antidegradation review “any alternatives that would be inconsistent with section 25-8-104 of the Water Quality Control Act shall not be considered available alternatives.”  If an issue should arise as to whether the antidegradation review criteria prohibiting material injury are being applied correctly to a specific proposed activity, that issue would be considered during that specific review process, including through consultation with the State Engineer and Water Conservation Board. 
The Commission received letters back from both the State Engineer and the Water Conservation Board, stating their agreement with the Commission’s preliminary assessment.  Upon consideration of all of the available information, the Commission has determined that the adoption of High Quality 2 designations in this proceeding does not cause material injury to water rights.  
A. 	Overview of Segment-Specific Changes
Three principal issues were in controversy for several of the segments addressed in this hearing.  The most controversial was whether to apply a high quality 2 designation to certain waters.  In several instances, designations proposed by the Water Quality Division were opposed on the basis that there was inadequate information to support such a designation.  The three most common challenges to the adequacy of the information were:  (1) detection limits for some data were too high to determine whether ambient quality was better than “table values;” (2) for some segments there was not adequate data for some or all of the twelve parameters referenced in section 3.1.8(2)(b)(i)(C); (3) for some segments the sample location(s) of available data were too limited to generalize the results to the whole segment. 
The Commission explicitly considered establishing minimum data requirements when it adopted the current antidegradation regulations, and consciously rejected that option.  Rather, the Commission recognized that it would be necessary to reply on best professional judgment to determine what constitutes representative date in a specific situation.  These issues are not new, or unique to high quality designations.  The Commission has for years been required to make water quality classifications and standards decisions in the absence of perfect information.  Requiring substantial, recently acquired data for all parameters from multiple locations in each segment before establishing high quality designations would assure that very few waters in Colorado would receive this protection for many years to come.  As a policy matter, the Commission has determined that high quality designations may appropriately be established based on a lower threshold of available data than that suggested by several parties to this proceeding. 
The Commission also notes that having adequate information upon which to base a high quality designation is not dependent solely on the availability of specific data for a particular segment.  Relevant information my include data from downstream segments, comparison of available data with that for similar streams, and information regarding the presence or absence of activities likely to adversely impact the quality of the segment in question. 
Where there is a substantial basis for considering a high quality 2 designation, in the face of some residual uncertainty the Commission has chosen or err in the direction of providing the protection.  This policy decision is strongly influenced by the ease with which designations can be changed if better data is developed in the future.  Unlike classifications, downgrading restrictions do not apply to water quality designations.  If new site-specific data is developed that demonstrates that a particular high quality designation is improper, it can and should be removed the Commission. 
With respect to detection limits, the Commission has chosen to continue the same policy that it has followed for over ten years—i.e. to treat data reported as below detection limits as being equivalent to zero. while other methodologies have been proposed and may be defensible, the Commission that this approach is reasonable and appropriate.  Requiring routine analysis to below table value standard levels for all constituents would substantially increase monitoring costs for the state and the public.  Moreover, the Commission believes that the “zero” assumption is fair, so long as it is applied consistently throughout the water quality regulatory system. 
Use of zeros in the water quality designation of standard-setting process may marginally err in the direction of increased protection.  However, when zeros are used in applying standards to specific dischargers, those dischargers benefit by the assumption that there is more assimilative capacity available in the stream (allowing higher levels of pollutants to be discharged) since the existing pollution is considered to be zero rather than some level between zero and the detection limit. 
The second recurring issue addressed for multiple segments in this hearing was whether to establish a recreation class 1 classification wherever a high quality 2 designation is established.  The Division proposed this classification change for applicable segments, since the high quality 2 designation indicates that such segments have adequate water quality to support the recreation class 1 use.  However, the Commission generally has declined to change the recreation classification from class 2 to class 1 in such circumstances, unless there was also evidence submitted that class 1 use were present or likely for the waters in question.  Unless the use is present or likely, application of use-protection-based water quality standards does not appear appropriate.  At the same time, the Commission notes that this approach does not diminish application of antidegradation protection requirements for high quality waters.  Where the existing quality is adequate, a high quality 2 designation has been established, requiring antidegradation requirements to be met before any degradation is allowed, even though the recreation classification is class 2. 
A related issue is the determination of which uses warrant the class 1 recreation classification.  The recreation classification definition in section 3.1.13 (1)(a)(i) of the Basic Standards and Methodologies for Surface Water refers to “activities when the ingestion of small quantities of water is likely to occur,” and states that “such waters include but are not limited to those used for swimming.”  In the past the Commission often has applied the class 1 classification only when swimming occurs, and not where other recreational uses that may result in ingestion of small quantities of water occur.  The Commission now believes it is appropriate for the class 1 classification also to be applied for uses such as rafting, kayaking, and water skiing. 
The appropriateness of recreation class 1 versus class 2 classifications was debated for several segments in the Gunnison Basin.  The Commission has received information regarding actual recreational uses.  It has also received substantial input regarding the property (of lack thereof) of broadening the application of the class 1 recreation classification, based upon an evolving interpretation of the Basic Standards language.  After lengthy discussion, the Commission has decided that it is appropriate as a matter of policy to begin in this basin to apply the recreation class 1 classification for all uses that involve a significant likelihood of ingesting water, including but not necessarily limited to rafting, kayaking, and water skiing.  The Commission received substantial testimony that kayaking often results in water ingestion.  In addition, the testimony presented, as well as the personal experience of individual Commissioners, indicates that rafting—white water or otherwise—also presents a significant potential for water ingestion. 
Section 3.1.6(1)(d) of the Basic Standards and Methodologies for Surface Water requires the Commission to establish classifications to protect all actual uses.  Therefore, for waterbodies where rafting and kayaking is an actual use, the recreation class 1 use classification should be applies, since ingestion of water is likely to occur.  The Commission sees no reason to distinguish between ingestion that may result from swimming and ingestion that may result from rafting or kayaking.  In fact there was some testimony indicating that ingestion is more likely to result from the latter activities.  
The Commission wishes to emphasize that the action that it is now taking is consistent with the existing definition of class 1 recreation uses.  Some of the comments submitted stated or suggested that the action now being taken by the Commission would constitute a “definitional change” that should be addressed only in a review of the Basic Standards and Methodologies for Surface Water.  No change in the regulatory definitions of the classifications is being considered or adopted at this time.  Rather, the Commission is applying what it believes to be the proper interpretation of the existing definition. 
The Commission believes that as a matter of policy it is not necessary or appropriate to wait until the July, 1991 rulemaking hearing regarding the Basic Standards and Methodologies for Surface Water to implement its current interpretation of the class 1 recreation classification.  Over the last decade, there have been many instances when arguments and facts presented in basin-specific rulemaking hearings have resulted in an evolving interpretation of the provisions of the Basic Standards and Methodologies for Surface Water.  This Commission is not bound by interpretations made by its predecessors in other basin-specific hearings.  To the degree that the class 1 recreation classification in the past has not been applied for some existing activities that involve a likelihood of ingesting water, the Commission now believes that such decision were in error. 
This action does not improperly exclude input from entities interested in other river basins.  First, the Commission specifically reopened this hearing and received input from entities not specifically concerned with the Gunnison basin.  Moreover, the Commission can further modify its policy if in other basin-specific reviews, or in the upcoming review of the Basic Standards and Methodologies, parties that did not participate in this proceeding bring forth new considerations that the Commission believes warrant a modification in the approach to recreation classifications that is now being adopted.  The Commission also does not believe that there was any problem with the notice provided for the specific segments at issue in the hearing.  Each of the segments for which the recreation classification is being changed from class 2 to class 1 based on rafting or kayaking uses were proposed to be changed to class 1 in the original hearing notice.  Although the basis for this proposal evolved during the hearing, any parties potentially concerned with a recreation class 1 classification were on notice that this change would be considered in this hearing. 
In applying the interpretation of the existing recreation class 1 definition that has been described, the Commission is also influenced by the fact that the importance of recreational uses of surface waters in Colorado has increased over the last decade.  Testimony indicated that uses such as rafting and kayaking have expanded substantially, and it is therefore even more important that adequate water quality protection now be provided. 
Some of the testimony submitted addressed the appropriateness of the current fecal coliform standards that are applied in association with recreation classifications.  The Commission believes that the appropriateness of the existing standards can and should be addressed, when and if there is new evidence available indicating that the current standards are not appropriate.  However, changes in such standards were not at issue in this hearing.  The Commission believes that questions regarding the appropriate numerical standards should not interfere with its obligation to establish appropriate classifications to protect existing uses.  If members of the public have information indicating that a different indicator parameter should be used, or that different fecal coliforms levels are appropriate for the respective recreation classifications, that issue can and should be considered in the upcoming review of the Basic Standards and Methodologies for Surface Water. 
Comment was also submitted to the Commission expressing concern regarding the potential effect of downgrading restrictions, should the Commission now adopt class 1 recreation classifications for certain waters and later change its views regarding the appropriate approach to recreation classifications.  The Commission does not believe that this presents a substantial problem.  Downgrading is appropriate only when a use is not in place.  So long as the class 1 recreation classification is defined as including activities that involve ingestion, applying that classification to waters where uses involving ingestion are present should not present a downgrading issue in the future.  If the Commission at some later date should completely revise its approach to, and definition of, recreation classifications, application of the new system would involve a set of “de novo” determinations, and not questions regarding upgrading or downgrading. 
The Commission recognizes the approach now being adopted may result in increased economic impacts for some dischargers, to meet the class 1 classifications.  The evidence submitted indicated that in many instances this will not be the case, because state-wide effluent limitations for fecal coliforms and chlorine standards to protect aquatic life will often drive the level of disinfection and dechlorination that are required.  However, in some circumstances it may be possible for the Division to consider an ex0anded use of seasonal effluent limitations that take low flow or high flow circumstances into account.  However, irrespective of these considerations, a potential increase in treatment requirements for dischargers cannot eliminate the Commission’s obligation to classify state waters to protect actual uses. 
Finally, concern was expressed that the approach now taken by the Commission will result in inconsistency regarding recreation classifications for different waters throughout the state.  Anytime a policy interpretation changes or evolves in any significant way, the first time the change is applied to specific state waters there will be some inconsistency among individual water bodies, since site-specific classifications and standards are addressed on a basin-by-basin basis.  However, it is the Commission’s intention to apply its policy interpretations consistently as individual basins are addressed. 
The third recurring issue was the proposal by several parties that the Commission substantially resegment several existing stream segments, creating additional segments.  The Commission generally has declined to resegment where there was not information submitted justifying different water quality designations, classifications or standards within separate portions of existing segments.  Where there is not such a basis for increasing the number of segments, the Commission believes that resegmentation would unnecessarily add additional complexity to the current system. 
B. 	Aquatic Life Class 1 with Table Values; New High Quality 2 Designations
Upper Gunnison River segments 4, 5, 6a, 6c, 7, 8, 10, 15, 19, 20, 25, 26, 27, 30 
Lower Gunnison River segment 1b 
San Miguel River segments 7b, 9, 10 
Lower Dolores River segments 1, 6  
Numerical standards for metals for these segments have in most instances been based on table values contained in Table III of the previous Basic Standards and Methodologies for Surface Water.  Table III has been substantially revised, effective September 30, 1988.  From the information available, it appears that the existing quality of these segments meets or exceeds the quality specified by the revised criteria in Table III, and new acute and chronic table value standards based thereon have therefore been adopted.  There are also come of these segments whose previous standards were based in party on ambient quality, since their quality did not met old table values based on alkalinity ranges.  However, these segments generally have much higher hardness than alkalinity, and the new table values (based on hardness-dependent equations) are now appropriate as standards. 
Existing use classifications for these segments have been retained, with the following exceptions.  A water supply classification has been added to Upper Gunnison segment 19 because the existing quality is adequate to protect these uses.  In addition, the recreation classifications for Upper Gunnison segment 15 and Lower Gunnison segment 1b have been changed from class 2 to class 1.  The Commission recognizes that this change could result in increased treatment costs for dischargers to segment 15.  However, the evidence demonstrated that class 1 recreation uses –i.e. rafting—are present in this segment.  Because their classifications, designations, and standards will now be the same, Lower Gunnison segment 1b has now been combined with segment 1a (discussed in section C, below). 
The descriptions of Upper Gunnison segments 20 and 23 have been revised, to consolidate several tributaries formally in segment 23 into segment 20.  The same designation, classifications and standards are appropriate for all of the waters now in segment 20.  Segment 23 is addressed under Paragraph F, below. 
Finally, a high quality 2 designation has been established for each of these segments.  The best available information in each case indicates that the existing quality for dissolved oxygen, pH, fecal coliform, cadmium, copper, iron, lead, manganese, mercury, selenium, silver and zinc is better than that specified in Tables I, II, and III of the Basic Standards and Methodologies for Surface Water, for the protection of aquatic life class 1 and recreation class 1 uses. 
C. 	Existing High Quality 2 Segments; New Classifications and Standards
Upper Gunnison River segments 1, 2, 3 
North Fork of the Gunnison segment 1 
Uncompahgre River segment 1’ 
Lower Gunnison segment 1a 
San Miguel segment 1 
These segments were already described as high quality class 2, and available information indicates that the parallel new high quality 2 designation continues to be appropriate for each.  All except Lower Gunnison segment 1a are within wilderness areas.  Lower Gunnison segment 1a is for the most part within the Black Canyon of the Gunnison National Monument and the entire segment is a renowned gold medal trout fishery.  In addition, the following use classifications, and associated table value standards, were adopted for these segments: 
Recreation – Class 1 
Cold Water Aquatic Life – Class 1 
Water Supply 
Agriculture 
These classifications and standards are appropriate based on the best available information regarding existing uses and quality.  These provisions would apply in the event that degradation is determined to be necessary following an activity-specific antidegradation is determined to be necessary following an activity-specific antidegradation review. 
The Commission rejected a proposal to resegment Lower Gunnison segment 1a into separate segments, because the evidence did not demonstrate that different designations, classifications, or standards are appropriate for different portions of this segment.  The USGS data offered in support of resegmentation was unconvincing due to concerns regarding its reliability.  Segment 1a has now been combined with segment 1b. 
D. 	New Use-Protected Designations; No Change in Numeric Standards
Upper Gunnison River segments 6a, 14, 16, 28, 32 
North Fork of the Gunnison segments 6, 10 
Uncompahgre River segments 10, 12 
Lower Gunnison River segment 4 
San Miguel River segment 12 
Lower Dolores River segment 4 
These segments all qualify for a use-protected designation based on their present classifications.  All are aquatic class 2 streams except Upper Gunnison segment 14 which has no aquatic life classification.  Existing standards are adopted because these segments have only a minimal number of standards with no metal or nutrient standards. 
E. 	New Use-Protected Designations; Revised Numeric Standards
Upper Gunnison River segment 11, 18 
Uncompahgre River segments 4, 5, 13 
Lower Gunnison River segments 6, 7, 8 
Lower Dolores River segment 5 
All of these segments, with the exception of Upper Gunnison segment 11, are aquatic life class 2 streams with numeric standards to protect the existing aquatic life.  The aquatic life classification for Upper Gunnison segment 18 has been changed from cold water class 1 to class 2.  Numerical standards for metals have in most instances been based on table values contained in Table III of the previous Basic Standards and Methodologies for Surface Water.  Table III has been substantially revised, effective September 30, 1988.  From the information available, it appears that the existing quality of these segments meets or exceeds the quality specified by the revised criteria in Table III, and new acute and chronic table value standards based thereon are adopted, except as specified below.  There are also some of these segments whose previous standards were based in part on ambient quality, since their quality did not meet old table values based on alkalinity ranges.  However, these segments generally have much higher hardness than alkalinity, and the new table values (based on hardness-dependent equations) are now appropriate as standards.  The one exception, Upper Gunnison segment 11, is a cold water class 1 stream that has three antidegradation parameters exceeding the table value criteria. 
Table value standards are adopted for all parameters for all segments noted in Paragraph E except as follows: 
Segment   			Constituents, ug/l
Upper Gunnison 11  	Cd(ch = 2.2, Cu(ch) = 20,     
Pb(ch) = 16, Zn(ch) = 400, No Acute standard for Cd, Cu or Zn/ 
Upper Gunnison 18  	NH3(ch) = 0.05 mg/l     
NH3(ch) = 0.02 mg/l from Co. Rd. 17 to confluence with Gunnison River.). 
Uncompahgre 4   	Fe(ch) = 2,800 (Trec), Se(ch) = 35 (Trec) 
The purpose of the qualifier on Upper Gunnison segment 18 is to provide additional protection for trout that are likely to use this reach for spawning or inhabit it during seasons when flow is present. 
F. 	No Change in Classification; No Designations; Revised Numeric Standards
Upper Gunnison segments 9, 12, 13, 17, 21a, 21b, 22, 23, 24, 29, 33 
North Fork Gunnison segments 2, 3, 4, 5, 7, 8, 9, 11 
Uncompahgre River segment 11, 14 
Lower Gunnison segments 3, 5 
San Miguel River segment 11 
Lower Dolores River segment 2 
These are water bodies whose classifications and standards are appropriate for high quality 2 designation, but for which either:  (1) the quality is not suitable for a water supply classification or 85th percentile values of one or two parameters exceed the criteria for class 1 aquatic life; or (2) the Commission has determined that there is currently inadequate information available upon which to base a high quality 2 designation. 
The segments that fall in the latter category are Upper Gunnison segments 22 and 33; North Fork segments 7 and 9, and Lower Gunnison segments 3 and 5.  For example, for Upper Gunnison segment 33 there is some data showing table value exceedances for two parameters.  Although the Division questioned the reliability of this data, no alternative data is available at this time.  However, the Commission also notes that table value standards, rather than ambient quality standards, have been established for this segment since the available data do not create a reliable basis for specific ambient quality standards at this time.  For North Fork segment 9, not only is there limited data available on this segment, but available information regarding other waters in this subbasin does not support the conclusion that these are high quality waters.  The Commission also rejected proposals to change the aquatic life classification of North Fork segment 7 to class 2 with a use-protected designation, and to resegment Lower Gunnison segment 3, because these proposals were not supported by the evidence. 
For North Fork segment 5, the Commission has rejected a proposal to change the recreation classification from class 1 to class 2.  This hearing was not noticed pursuant to section 25-8-207, C.R.S., which provides authority to revise classifications based on material assumptions that were in error or no longer apply.  If one of the parties, or any other member of the public, believes that the current classification is in error and that it may have an adverse impact on their activities, such a hearing may be requested in the future to consider this issue. 
The Division proposed that the recreation classification for North Fork segment 3 be changed from class 2 to class 1.  The Commission rejected this proposal due to inadequate information that such uses are in place or likely. 
Table value standards are adopted for all parameters for all segments noted in Paragraph F except as follows: 
Segment    			Constituent(s), ug/l
Upper Gunnison 9   		Zn(ch) = 80 
Upper Gunnison 17   		Fe(ch) = 1,600 (Trec) 
Upper Gunnison 21a   		U(ch) = 2,000 
Upper Gunnison 21b   		U(ch) = 300 
Upper Gunnison 22   		Fe(ch) = 1,1,80 (Trec) 
North Fork Gunnison 4  		Fe(ch) = 1,500 (Trec) 
North Fork Gunnison 5  		Fe(ch) = 1,900 (Trec) 
Uncompahgre River 11  	Fe(ch) = 1,600 (Trec) 
Lower Dolores 2    		Fe(ch) = 2,600 (Trec) 
In addition, three-year temporary modifications have been adopted for the following segments and parameters: 
Segment    			Constituent(s), ug/l
Upper Gunnison 12  		Cd(ch) = 10 (Trec); Zn(ch) = 790 (Trec) 
Upper Gunnison 13  		Cd(ch) = 10 (Trec), Zn(ch) = 1,080 (Trec) 
Upper Gunnison 23  		Ag(ch)=0.5 
G. 	Changes in Classification; No designations; Revised Numeric Standards
Lower Gunnison River segment 2 
San Miguel River Segments 4, 5 
Lower Dolores River segment 3 
Review of available data and existing uses indicates that Lower Gunnison segment 2 and Lower Dolores segment 3 are appropriate to be upgraded to recreation class 1 with a corresponding fecal coliform standard of 200 MPN/100 ml.  The agricultural use classification has been adopted to San Miguel segments 4 and 5.  Table value standards have been adopted for all parameters on all segments except for ambient standards for iron of 2,300 ug/l on Lower Gunnison segment 2 and 2,800 ug/l on Lower Dolores segment 3. 
H. 	No change in Classifications or Standards
Upper Gunnison segment 31 
Uncompahgre River segments 2, 3, 6, 7, 8, 9a, 9b 
San Miguel River segments 2, 3a, 3b, 6a, 6b, 7a, 8 
Upper Gunnison segment 31 and San Miguel River segments 7a and 8 are segments with several ambient standards based on total recoverable data.  No new data was available to indicate that table value standards are appropriate and/or make the conversion to a dissolved metals basis for the ambient standards. 
The remainder of the segments on the Uncompahgre and San Miguel are either directly involved in CERCLA litigations or may be influenced by them.  In view of the current status of these CERCLA actions, the Commission has agreed to address these segments in the next triennial review.  The Commission has requested the Division to notify it if any new discharges are proposed for these segments prior to that time, so that an earlier hearing can be held. 
35.17 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; NOVEMBER 2, 1992:
The provisions of 25-8-202; 204; and 402 C.R.S. provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4), C.R.S., the following statement of basis and purpose. 
BASIS AND PURPOSE: 
The Commission adopted temporary modifications for Segments 12 and 13 as a result of its May 1990 hearing on the Gunnison and Lower Dolores River Basins.  These temporary modifications are scheduled to expire July 1, 1993.  A hearing for the Gunnison and Lower Dolores River Basins has been scheduled by the Commission for December 5, 1994.  The Commission extended the expiration date of the temporary modifications to December 31, 1994, so that the Commission will have an opportunity to hear evidence as to whether these temporary modifications continue to be necessary. 
35.18 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; MARCH 1, 1993 HEARING:
The provisions of 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4), C.R.S., the following statement of basis and purpose. 
BASIS AND PURPOSE: 
The changes to the designation column eliminating the old High Quality 1 and 2 (HQ1, HQ2) designations, and replacing HQ1 with Outstanding Waters (OW) designation were made to reflect the new mandates of section 25-8-209 of the Colorado Water Quality Act which was amended by HB 92-1200.  The Commission believes that the immediate adoption of these changes and the proposals contained in the hearing notice is preferable to the alternative of waiting to adopt them in the individual basin hearings over the next three years.  Adoption now should remove any potential for misinterpretation of the classifications and standards in the interim. 
In addition, the Commission made the following minor revisions to all basin segments to conform them to the most recent regulatory changes: 
1. 	The glossary of abbreviations and symbols were out of date and have been replaced by an updated version in section 3.5.6(2). 
2. 	The organic standards in the Basic Standards were amended in October, 1991, which was subsequent to the basin hearings.  The existing table was based on pre-1991 organic standards and are out of date and no longer relevant.  Deleting the existing table and referencing the Basic Standards will eliminate any confusion as to which standards are applicable. 
3. 	The table value for ammonia and zinc in the Basic Standards was revised in October, 1991.  The change to the latest table value will bring a consistency between the tables in the basin standards and Basic Standards. 
4. 	The addition of acute un-ionized ammonia is meant to bring a consistency with all other standards that have both the acute and chronic values listed.  The change in the chlorine standard is based on the adoption of new acute and chronic chlorine criteria in the Basic Standards in October, 1991. 
Finally, the Commission confirms that in no case will any of the minor update changes described above change or override any segment-specific water quality standards. 
35.19 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY, AND PURPOSE, September 7, 1993:
The provisions of 25-8-202(1)(b) and (2); 25-8-203; 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted, in compliance with 24-4-103(4), C.R.S., the following Statement of Basis and Purpose. 
BASIS AND PURPOSE: 
On November 30, 1991, revisions to “The Basic Standards and Methodologies for Surface Water:,. 3.1.0 ( 5 CCR 1002-8), became effective.  As part of the revisions, the averaging period for the selenium criterion to be applied as a standard to a drinking water supply classification was changed from a 1-day to a 30-day duration.  The site-specific standards for selenium on drinking water supply segments were to be changed at the time of rulemaking for the particular basin.  Only one river basin, the South Platte, has gone through basin-wide rulemaking since these revisions to the “Basic Standards”.  Through an oversight, the selenium standards was not addressed in the rulemaking for this basin and has since become an issue in a wasteload allocation being developed for segment 15 and 16 of the South Platte.  Agreement on the wasteloads for selenium is dependent upon a 30-day averaging period for selenium limits in the effected parties permits.  Therefore, the parties requested that a rulemaking hearing be held for the South Platte Basin to address changing the designations of the 10 ug/l to a 30-day standard.  The Water Quality Control Division, foreseeing the possibility of a selenium issue arising elsewhere in the state, made a counter proposal to have one hearing to change the designation for the selenium standard on all water supply segments statewide.  The Commission and the parties concerned with South Platte segments 15 and 16 agreed that this would be most judicious way to address the issue. 
The change in the averaging period may cause a slight increase in selenium loads to those segments which have CPDS permits regulating selenium on the basis of a water supply standard.  However, these segments are only five in number and the use will still be fully protected on the basis that the selenium criterion is based on 1975 national interim primary drinking water regulations which assumed selenium to be a potential carcinogen.  It has since been categorized as a non-carcinogen and new national primary drinking water regulations were promulgated in 1991 that raised the standard to 50 ug/l. 
The Commission also corrected a type error in the TVS for Silver by changing the sign on the exponent for the chronic standard for Trout from + 10.51 to – 10.51. 
35.20 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY, AND PURPOSE (February, 1995 Rulemaking)
The provisions of 25-8-202(1)(b) and (2); 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted, in compliance with 24-4-103(4), C.R.S., the following Statement of Basis and Purpose. 
BASIS AND PURPOSE: 
The temporary modifications addressed in this hearing for segments 12 and 13 of the Upper Gunnison River, for cadmium and zinc, were previously adopted with an expiration date of December 31, 1994.  For efficient utilization of resources, the Commission has extended the temporary modifications to December 31, 1996, so that these temporary modifications can be considered along with other issues in the overall Gunnison River Basin rulemaking hearing.   
35.21 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE (1995 Silver hearing) 
The provisions of C.R.S. 25-8-202(1)(b), (2) and 25-8-204; provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4) C.R.S. the following statement of basis and purpose. 
BASIS AND PURPOSE: 
The changes described below are being adopted simultaneously for surface water in all Colorado river basins. 
This action implements revisions to the Basic Standards and Methodologies for Surface Water adopted by the Commission in January, 1995.  As part of a July, 1994 rulemaking hearing, the Commission considered the proposal of various parties to delete the chronic and chronic (trout) table values for silver in Table III of the Basic Standards.  As a result of that hearing, the Commission found that the evidence demonstrated that ionic silver causes chronic toxicity to fish at levels below that established by the acute table values.  It was undisputed that silver is present in Colorado streams and in the effluent of municipal and industrial dischargers in Colorado.  The evidence also demonstrated that the removal of silver from wastewater can be costly.  However, there was strongly conflicting scientific evidence regarding the degree to which silver does, or could in the absence of chronic standards, result in actual toxicity to aquatic life in Colorado surface waters.  In particular, there was conflicting evidence regarding the degree to which the toxic effects of free silver are mitigated by reaction with soluble ligands to form less toxic compounds and by adsorption to particulates and sediments. 
The Commission concluded that there is a need for additional analysis of the potential chronic toxicity of silver in streams in Colorado.  The Commission encouraged the participants in that hearing, and any other interested parties, to work together to develop additional information that will help resolve the differences in scientific opinions that were presented in the hearing.  The Commission believes that it should be possible to develop such information within the next three years. 
In the meantime, the Commission decided as a matter of policy to take two actions.  First, the chronic and chronic (trout) table values for silver have been repealed for the next three years.  The Commission is now implementing this action by also repealing for the next three years, in this separate rulemaking hearing, all current chronic table value standards for silver previously established on surface waters in Colorado.  Any acute silver standards and any site-specific silver standards not based on the chronic table values will remain in effect.  The Commission intends that any discharge permits issued or renewed during this period will not include effluent limitations based on chronic table value standards, since such standards will not currently be in effect.  In addition, at the request of any discharger, any such effluent limitations currently in permits should be deleted. 
The second action taken by the Commission was the readoption of the chronic and chronic (trout) table values for silver, with a delayed effective date of three years from the effective date of final action.  The Commission also is implementing this action by readopting chronic silver standards with a corresponding delayed effective date at the same time that such standards are deleted from the individual basins.  The Commission has determined that this is an appropriate policy choice to encourage efforts to reduce or eliminate the current scientific uncertainty regarding in-stream silver toxicity, and to assure that Colorado aquatic life are protected from chronic silver toxicity if additional scientific information is not developed.  If the current scientific uncertainty persists after three years, the Commission believes that it should be resolved by assuring protection of aquatic life. 
In summary, in balancing the policy considerations resulting from the facts presented in the July 1994 rulemaking hearing and in this hearing, the Commission has chosen to provide relief for dischargers from the potential cost of treatment to meet chronic silver standards during the next three years, while also providing that such standards will again become effective after three years if additional scientific information does not shed further light on the need, or lack of need, for such standards. 
Finally, the Division notes that arsenic is listed as a TVS standard in all cases where the Water Supply classification is not present.  This is misleading since Table III in the Basic Standards lists an acute aquatic life criterion of 360 ug/l and a chronic criterion of 150 ug/l for arsenic, but a more restrictive agriculture criterion of 100 ug/l. It would be clearer to the reader of the basin standards if, for each instance where the standard "As(ac/ch)=TVS" appears, the standard "As=100(Trec)" is being inserted as a replacement.  This change should make it clear that the agriculture protection standard would prevail in those instances where the more restrictive water supply use protective standard (50 ug/l) was not appropriate because that classification was absent. 
The chemical symbol for antimony (Sb) was inadvertently left out of the "Tables" section which precedes the list of segments in each set of basin standards.  The correction of this oversight will aid the reader in understanding the content of the segment standards.  Also preceding the list of segment standards in each basin is a table showing the Table Value Standards for aquatic life protection which are then referred to as "TVS" in the segment listings.  For cadmium, two equations for an acute table value standard should be shown, one for all aquatic life, and one where trout are present.  A third equation for chronic table value should also be listed.  The order of these three equations should be revised to first list the acute equation, next the acute (trout) equation, followed by the chronic equation.  This change will also aid the reader in understanding the intent of the Table Value Standards. 
PARTIES TO THE PUBLIC RULEMAKING HEARING JUNE 12, 1995 
1. Coors Brewing Company 
2. The Silver Coalition 
3. Cyprus Climax Metals Company 
4. The City of Fort Collins 
5. The City of Colorado Springs 
35.22 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE (December, 1995 Rulemaking) 
The provisions of C.R.S. 25-8-202(1)(b), (2); 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4) C.R.S. the following Statement of Basis and Purpose. 
BASIS AND PURPOSE: 
The temporary modifications addressed in this hearing for segments 12 and 13 of the Upper Gunnison river, for cadmium and zinc, were previously adopted with an expiration date of December 31, 1996.  For efficient utilization of resources, the Commission has extended the temporary modifications to December 31, 1997, so that these temporary modifications can be considered along with other issues in the overall Gunnison River Basin rulemaking hearing, which is currently scheduled for June, 1997. 
35.23 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE (June, 1997 hearing)
The provisions of 25-8-202(1)(a), (b) and (2), 25-8-203; 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted, in compliance with 25-4-103(4) C.R.S. the following statement of basis and purpose. 
BASIS AND PURPOSE:
1. 	Resegmentation
Extensive renumbering of segments was made throughout the basin due to information which showed that: 
a. 	The original reasons for segmentation no longer applied. 
b. 	New water quality data showed that streams should be resegmented based on changes in their water quality. 
c. 	Certain segments could be grouped together in one segment because they had similar quality and uses. 
d. 	Certain segments were originally listed under the incorrect basin and have now been listed in the appropriate basin. 
2. 	Wetlands
In March, 1993, the Commission amended the Basic Standards and Methodologies for Surface Water, Regulation 31 (5 CCR 1002-31) to include wetlands in the stream classification and standards system for the state.  Due to that action, it became necessary to revise the segment description for all segments of the “all tributary” type to clarify that wetlands were also part of the tributary system for a given mainstem segment.  All tributary wetlands now clearly carry the same classifications and standards as the stream to which they are tributary as provided for in 31.13(1)(e)(iv). 
Information was submitted in the hearing that the Water Quality Control Division has been working with the Colorado Geological Survey to develop methodologies to measure the functions of wetlands.  The development of such methodologies is an important implementation issue with respect to water quality standards for wetlands and the supports the Division’s efforts in this regard. 
3. 	Manganese Standards
On all segments classified for water supply and aquatic life uses, the total recoverable manganese standard of 1,000 ug/l was stricken.  The aquatic life manganese criterion was changed in 1991 revisions to the Basic Standards from total recoverable to dissolved and on these segments a more stringent dissolved manganese water supply standard of 50 ug/l is in place.  On segments classified for aquatic life and not water supply, the 1000 ug/l standard is designated as dissolved. 
4. 	Mercury Standard
The Basic Standards include the note that the standard for mercury is based on the Final Residual Value (FRV), and that mercury in the total form is the proper way to express that value.  Therefore, the Commission decided to change the (TREC) notation for mercury to (tot) in all cases where it appeared. 
5. 	Conversion to Dissolved Metals
Several segments in the previous version of the classifications and standards for these basins contained standards for metals as “total recoverable”.  The Commission previously determined that standards for most metals should be expressed as dissolved, necessitating conversion of those metals standards for the following segments: 
Upper Gunnison Basin segments 11 and 12 (previously segments 12 and 13; temporary modifications for total recoverable metals deleted), 29 (previously segment 31). 
Uncompahgre River segments 2, 3, 7, 8, and 9. San Miguel River segments 2, 3a, 3b, 6a, 6b, 7a and 8. 
6. 	Changes Necessary to Comply with “Swimmable” Requirements
The Commission has reached an understanding with EPA regarding the classification and standards necessary to comply with the goal established in the federal Clean Water Act that all waters of the nation be suitable for recreation in and on the water.  In Colorado, that requirement translates into a Recreation, Class 1, with the 200 fecal coliform/100 ml standard wherever swimming, rafting, etc. are in place or have the potential to occur; Recreation, Class 2, with 200 fecal coliform/100 ml standard wherever secondary contact recreation only is practiced, and the existing quality supports a class 1 recreation use and with consideration of the lack of significant increased treatment costs; and Recreation, Class 2, with the 2000 fecal coliform/100 ml standard in most other situations.  This policy has resulted in recreation classification and/or fecal coliform standard modifications to the following segments: 
Upper Gunnison Basin segments 4, 5, 6a and 6b (previously 6b and 6c), 7, segments 8 through 12 (previously 9 through 13), segments 16 through 19 (previously 17 through 20), segments 21 through 24 (previously 22 through 25), segment 26 (previously 27), segments 28 through 30 (previously 29 through 31), and segment 32 (previously 33). 
North Fork Gunnison segment 2. 
Uncompahgre River segments 3, 5, 7, 8, 9 (previously 9a), 13, and 15. 
Lower Gunnison River segments 6, 7, 8, and segments 10 and 11 (previously North Fork  segments 8 and 9). 
San Miguel River segments 3b, 4, 5, and 8. 
Dolores River segments 4 and 5 (previously 5 and 6). 
Concerns were raised in this hearing regarding the potential impact of more stringent fecal coliform standards on agricultural and ranching practices.  Ranching and agriculture have been extensive in the Upper Gunnison River Basin.  The Upper Basin Parties submitted testimony that these uses date back to the late 1800s and have been a continuing integral economic and social factor in the basin.  The Commission recognizes the extent of this use of land within the basin, and that ranching and agriculture have co-existed with a high level of water quality in the basin.  The Commission summarizes the extent of agricultural and ranching use within the basin as a helpful baseline should issues involving compliance with fecal coliform standards in the future involve agricultural and ranching activities. 
The testimony submitted indicates that the large majority of water rights and uses within the basin are decreed for agricultural uses.  There are approximately 1,500 absolute ditch rights within the basin decreed only for agricultural and irrigation uses, representing total decreed diversions of more than 7,700 c.f.s.  As of 1997, the following acreage was classified within the basin as agricultural for taxing purposes: 
County   			Acres
Gunnison  			343,742 
Hinsdale    			7,292 
Saguache   			54,299 
The testimony also indicated that the Colorado Agricultural Statistics Service census of 1992 shows the total number of cattle and calves in Gunnison County as 30,713 head, and the Service estimates the total number as of January 1, 1997, was 31,343.  The BLM reports there are 85 grazing permeates and 45,133 AUMs within its Gunnison Resource Area.  The Forest Service reports that within its Taylor River Ranger District, there are 29 active allotments, encompassing 688,260 Forest Service acres, and a total number of 9,119 permitted livestock, and 8,893 of authorized livestock.  Within the Cebolla Ranger District, the Forest Service reports there are 36 active allotments encompassing 552,529 acres, and a total number of 12,662 permitted livestock, and 13,395 authorized livestock. 
The Commission finds that this degree of agricultural activities in the Gunnison Basin has existed in this region while the fecal coliform levels have been maintained at lower concentrations than the more stringent fecal coliform standards being adopted for a number of stream segments, as described above. 
The Commission has previously stated that the fecal coliform standard is to be implemented with a rebuttable presumption that high densities of fecal coliform identified in water quality samples are due to human fecal pollution.  The focus of the existing regulatory system for bacteriological parameters is on identifying and controlling sources of human waste that may be discharged to waters of the state without adequate treatment. 
Parties to the hearing also proposed that the Commission adopt “an additional indicator that would distinguish between human fecal coliform and animal fecal coliform.”  Based on the information submitted, it does not appear that any such indicator is available at this time.  
7. 	Upgrading of Class 2 Aquatic Life Segments
The Commission decided to adopt upgraded classifications and/or a more complete set of standards for several segments where the Division recommended such changes based on recent sampling of the biota by the Division of Wildlife (DOW) and the Water Quality Control Division.  In general, these segments were previously thought to contain very little aquatic life, and were appropriate for the Class 2, minimal standards application found on most intermittent streams.  However, the biological data referred to above indicated that a more diverse and rich aquatic life community existed, including threatened species.  The Commission has chosen to recognize these facts by the adoption of a higher aquatic life classification and/or a complete set of protective standards.  The segments/streams affected are: 
Uncompahgre River segment 15. 
Lower Gunnison River segment 9. 
In addition, based on testimony by the Division of Wildlife, several specific creeks that had been included in segments with minimal standards were moved to segments with the usual aquatic life table value standards.  These creeks are now located in: 
Upper Gunnison segment 6b. 
Uncompahgre segment 11. 
San Miguel segment 10. 
Lower Dolores segment 5. 
8. 	Full Standards Not Applied to Aquatic Life Segments
EPA raised the issue of why the full set of inorganic aquatic life protection standards were not applied to various segments recommended for aquatic life class 2 classification.  These segments typically were assigned only dissolved oxygen, pH, and fecal coliform standards.  It was EPA’s position that if there were dischargers located on the segments with the potential to produce toxic levels of one or more of the pollutants not contained in the abbreviated list of standards, the aquatic life in the segment could be jeopardized.  Rather than adopt the full set of inorganic standards, the Commission was persuaded by the Division’s arguments that the abbreviated list of standards was sufficient to protect the rudimentary aquatic life found in these intermittent streams, and that there was a very low probability that any of the few dischargers located on these segments would discharge toxic effluents.  The segments where this policy was followed are: 
Upper Gunnison Basin segments 6a, 13 (formerly 14), 15 (formerly 16), 27 and 31. 
North Fork Gunnison segment 6. 
Uncompahgre River segments 6, 10, and 12. 
Lower Gunnison River segments 4, and 12. 
San Miguel River segment 12. 
Dolores River segment 3.  
As noted above, where specific creeks within these segments were identified with aquatic life that warrants additional standards, they were moved into segments with the usual aquatic life table value standards. 
9. 	Outstanding Waters Designations
The Commission followed the recommendations of the Division in assigning the Outstanding Waters (OW) designation to all waters covered by this regulation that are within the La Garita, West Elk, Collegiate Peaks, Maroon Bells, Ragged, Oh-Be-Joyful, Big Blue, Mt. Sneffels, and Lizard Head  wilderness areas.  Division water quality data indicated all antidegradation parameters to be well within table values and several of the wilderness waters provided habitat to ecologically significant specifies, i.e. Colorado River cutthroat trout and the boreal toad.   
Uncompahgre River segment 1. 
North Fork Gunnison segment 1. 
San Miguel River segment 1.  (Waters of the Sneffels Wilderness Area within the San Miguel watershed were added to Segment 1.) 
The Commission also rejected a proposal by the High Country Citizens’ Alliance (HCCA) and  Western Slope Environmental Resource Council (WSERC) to adopt an outstanding waters designation for Upper Gunnison segment 25 and Lower Gunnison segment 1.  These segments--which include Blue Mesa, Morrow Point and Crystal Reservoirs, as well as the Black Canyon of the Gunnison and the Gunnison Gorge--are located downstream of significant development in the Gunnison Basin and include reservoirs that are actively managed for a variety of purposes.  The Commission does not believe that a showing has been made that adoption of the outstanding waters designation is necessary and appropriate for these waters at this time.  The Commission is receptive to hearing future proposals regarding the adoption of outstanding waters designation or other forms of extra protection for these waters, supported by additional research and information regarding the implications of such protection for other activities in or upstream from such segments, particularly if broad support for any such proposals can be developed. 
10. 	Use-Protected Designations
In a previous “Basic Standards” rulemaking, the Commission changed the basis for assigning the use-protected designation by eliminating the automatic assignment where recreation class 2 was a classified use.  In this comprehensive review of the basin classifications, designations, and standards, the Commission removed one use-protected designation in order to be consistent with that Basic Standards revision.  This segment is: 
Upper Gunnison Basin segment 10 (previously segment 11). 
In addition, the Commission added the use-protected designation to several segments that met the criteria for use-protected.  These are: 
Uncompahgre River segments 6, 7, 8, 9, and 15. Lower Gunnison River segment 9. 
The Commission also rejected a proposal by HCCA and WSERC to remove the use-protected designations for several other stream segments.  In each instance, the segments in question are classified as aquatic life class 2.  The Basic Standards and Methodologies for Surface Water provide that this classification requires a use-protected designation, unless the Commission determines “that those waters with exceptional recreational or ecological significance should be undesignated, and deserving of the protection afforded by the antidegradation review provisions.”  Section 31.8(2)(b)(i).  The evidence submitted in this hearing was not adequate to support such a finding. 
11. 	Ambient Quality-Based Standards
The Division presented extensive information in its Exhibit 1 regarding ambient chemical quality of many segments in the basin.  In most cases ambient quality was well within the “table value” limits prescribed by the Basic Standards for the protection of the various classified uses, prompting the Commission to assign those table values as segment standards.  In a few cases, however, ambient quality exceeded the table values, yet there was information to suggest that the use was in place nonetheless.  The available information lead to the conclusion that there was little hope of reversing the cause for degradation within twenty years.  In those instances, the Commission followed the recommendation of the Division to adopt the 85th percentile of the ambient data as the standard (ambient quality-based standard).  The following is a list of those segments where such standards have been adopted: 
Upper Gunnison Basin segments 10, 11, 12 (formerly 11, 12, and 13) and 31. 
North Fork Gunnison segment 4. 
Uncompahgre River segments 2, 3, 4, and 7. 
EPA expressed concern in the hearing regarding the basis for adopting ambient quality-based water quality standards.  The Commission encourages the Division to work with EPA to explore the potential for developing more standardized criteria for determining that such standards are appropriate on a site-specific basis. 
12. 	Temporary Modifications 
In several instances, the Commission decided to establish temporary modifications to table value standards as an alternative to establishing an ambient-based standard.  This practice was followed where these was information to suggest the underlying standard could be met within three years to five years, or where there were questions surrounding the data which could be clarified with additional sampling.  Temporary modifications adopted for several segments for selenium standards are discussed separately below.  The segments where other temporary modifications were established or modified are: 
Upper Gunnison segment 8. 
Uncompahgre segment 4. 
Lower Gunnison River segment 9. 
San Miguel River segments 3a and 3b.  (See separate discussion below.) 
13. 	Water + Fish Organics Applied to Aquatic Life Segments
It is the policy of the Commission to establish the water+fish organics standards found in the Basic Standards for those Class 2 aquatic life segments where fish of a catchable size and which are normally consumed are present and there is evidence that angling takes place on a recurring basis.  Based on these criteria and the testimony submitted, the Commission has chosen to assign the water+fish organics standards to the following class 2 aquatic life segments: 
Uncompahgre River segments 4, 9 and 13. 
Lower Gunnison River segments 7 and 8. 
14. 	Selenium Standards
In October of 1995, the Commission promulgated new aquatic life table value standards (TVS) for selenium, i.e., 20 ug/l acute and 5 ug/l chronic.  At that time, the Commission adopted a footnote to the TVS which acknowledged that “selenium is a bioaccumulative metal and subject to a range of toxicity values depending upon numerous site-specific variables.”  The simultaneously adopted Statement of Basis and Purpose further elaborated upon this point, indicating that there exists the opportunity to develop “ambient or site-specific water quality standards on a basin-by-basin or specific segment basis,” and identifying a number of site-specific factors that may be pertinent in the establishment of appropriate standards.  Finally, the Commission noted that “a selenium standard need not be adopted during the course of triennial or segment specific rulemakings unless it is determined that the discharge or presence of selenium in the affected waters reasonably could be expected to interfere with the classified uses . . ..” 
In this basin-specific rulemaking, the Commission has decided to adopt the selenium TVS for most segments in the Gunnison and Lower Dolores basins.  Temporary modifications, however, based on the 85th percentile of ambient data with an underlying TVS of 5 ug/l chronic and 20 ug/l acute, have been adopted for the segments identified below. 
Uncompahgre River Segment 4. 
Uncompahgre River Segment 14 (Sweitzer Lake). 
Lower Gunnison River Segment 2. 
North Fork Gunnison River Segment 5. 
The Commission may revisit the question of ambient standards at some point in the future. 
The Commission is hopeful that adoption of temporary modifications for these four segments will assist in reducing the existing high selenium levels.  This action will establish interim goal-based criteria for selenium on these segments, ensure that there will be no further increases in selenium concentration for these waters as a result of regulated sources, and provide a mechanism to spur progress in improving water quality and attaining the goal-based standard.  Furthermore, the temporary modifications may assist the Division in writing NPDES permits for any point source discharges while restoration efforts for nonpoint sources of selenium are underway - the temporary modification will serve as the basis for calculating the interim effluent limits for such permits. 
Most important, however, the temporary modifications provide a mechanism to address the existing high selenium concentrations in these segments.  For example, adoption of temporary modifications will allow these segments to be listed pursuant to Clean Water Act (CWA) section 303(d) and section 305(b) - sections of the Act which require identification of water quality-limited segments.  These listings, in turn, will increase the potential for funding for selenium control projects.  Although it may become necessary to further revise the selenium numeric standards as additional information becomes available, it is hoped that this action will benefit efforts aimed at reducing the existing high selenium levels in these four segments. 
In adopting the above standards and temporary modifications, the Commission took into consideration a number of factors, including statements from EPA and the USFWS that an ambient standard for the above-referenced segments may not be approved by EPA because of concerns over (i) the potential impacts of such an elevated concentration upon fish and wildlife, with specific reference to the federally listed endangered species in the Lower Gunnison River Segment 2; (ii) the need for EPA to meet its consultation responsibilities under Section 7 of the Endangered Species Act; and (iii) the uncertainty as to whether the present condition is reversible. 
The Commission acknowledges that there is also uncertainty associated with what will eventually prove to be the appropriate selenium standard for segments in this basin.  For example, EPA is currently reexamining its national criteria for selenium.  The USFWS is completing additional work on the potential impact of selenium upon razorback suckers, with a final report due in early 1998.  Additional work is also being performed upon perfecting site specific methods of standard determination, including a sediment-total organic carbon model and uptake of selenium in aquatic biota. 
Additional uncertainties presently exist concerning (i) the relative contributions of varying sources to the existing high ambient levels; (ii) whether these levels can be significantly reduced within 20 years or, stated another way, the pace of restoration efforts; (iii) what BMPs or other treatment technology exists or may be developed in the near future to achieve such a reduction; and (iv) the extent of measurable improvements in the aquatic ecosystem if the underlying TVS of 5 ug/l chronic is achieved. 
Furthermore, it is currently unknown whether adequate funds can be found to undertake prevention and remediation measures, with specific reference to the control of nonpoint sources of selenium loading.  The interested parties, together with the EPA, USFWS, and the Division shall cooperate in identifying sources of funds and, to the extent possible, obtaining needed monies, including funds which may be available under Section 319 of the Clean Water Act, from the US Department of Agriculture pursuant to the Environmental Quality Improvement Program (EQIP), the US Bureau of Reclamation through the Colorado River Salinity Control Program or the US Department of Interior through the Irrigation Drainage Program.  The EPA, USFWS, and the Division, in their testimony, agreed to express to the Colorado River Basin Salinity Control Forum, in writing, their position that salinity control projects which simultaneously reduce loading should receive funding priority. 
The interested parties to the hearing, the federal agencies, and landowners in the vicinity of the affected reaches have expressed an interest in employing voluntary, cooperative prevention and remediation practices for purposes of reducing selenium loading and improving water quality.  The Commission encourages the formation of a Task Force for this purpose, and urges the Division to cooperate in such an effort.  This Task Force could employ the TMDL concept in seeking to achieve the underlying TVS for selenium. 
The Division has indicated to the Commission that it may take a minimum of five years to identify, fund and implement selenium control projects in these basins which may measurably improve water quality in the segments of concern.  Thus, though the segments with a temporary modification will be reviewed at the end of three years, it is not anticipated that there will be any significant changes at that time. 
15. 	Site-Specific Issues
a. 	Coal Creek
In response to a proposal by Climax Molybdenum Company (CMC), the Commission has adopted ambient quality-based standards for several metals for Coal Creek, segments 11 and 12 of the Upper Gunnison Basin (formerly segments 12 and 13).  CMC submitted evidence that elevated metals levels in these segments are caused by “natural or irreversible man-induced” impacts.  In adopting these standards, the Commission recognizes the following agreements between the parties with respect to these segments: 
CMC agrees to assist HCCA in performing a reconnaissance study consisting of physical surveillance and high flow and low flow water quality monitoring in segment 11 with the objective of identifying sources of Cd, Fe, Mn and Zn. 
CMC agrees to work with other parties, which may include the Town of Crested Butte and Gunnison County, to pursue development of a remedial project (or projects) to be funded by the section 319 nonpoint source grant program if such project (or projects) appear feasible. 
HCCA agrees to support the adoption of the ambient based standards proposed by CMC for segments 11 and 12. 
b. 	Indian Creek
Homestake Mining Company expressed concern about the Division’s initial proposal to eliminate separate segments for Indian Creek (formerly Upper Gunnison segments 21a and 21b) and to add these waters into the segment for Marshall Creek (formerly Upper Gunnison segment 22).  Following consideration of the evidence, including an agreement between the Division and Homestake, the Commission has left the upper portion of Indian Creek (formerly segment 21a, now segment 20) as a separate segment.  The lower portion of Indian Creek (formerly segment 21b) has been added to the Marshall Creek segment (formerly segment 22, now segment 21). 
c. 	North Fork segments 2 and 3
The Commission considered a proposal by HCCA and WSERC to move the segment boundary between North Fork segments 2 and 3 further downstream, to account for primary contact recreation activities in the upper portion of segment 3 as previously defined.  The evidence does demonstrate that primary contact recreation uses currently occur in these waters.  Following an extensive discussion of alternative potential resegmentation options, the Commission has established the new segment boundary at the Black Bridge, on which 4175 Drive crosses the river.  The evidence indicates that the majority of the primary contact recreation use occurs above that point. 
d. 	Fruitgrowers Reservoir
In response to a proposal by the Division, the Commission has established a new segment for Fruitgrowers Reservoir--segment 9 in the Lower Gunnison Basin.  The evidence demonstrates that aquatic life class 2, recreation class 1 and agriculture are appropriate classifications for this reservoir based on actual current or recent past uses of these waters.  In view of the reservoir’s current degraded quality, the Commission has adopted a goal qualifier for the recreation classification and temporary modifications for the un-ionized ammonia and fecal coliform standards.  The Commission appreciates and wishes to encourage the efforts of interested entities in the area to undertake a cooperative, inter-governmental two-year study to better determine the cause of current water quality problems in the reservoir.  The Commission requests that the Division provide to the Commission an update regarding the status of these study efforts in the fall of 1998.  
e. 	San Miguel segments 3a and 3b
The extensive data submitted in evidence demonstrate that the zinc levels in San Miguel River segments 3a and 3b exceed the current numeric standard of 190 ug/l of dissolved zinc (chronic) applicable to both segments.  It is unclear whether that standard can be met within 20 years.  Under a 1992 Consent Decree with the State of Colorado, Idarado Mining Company is pursuing activities pursuant to a Remedial Action Plan ("RAP") to remediate historic mining impacts in the upper reaches of the San Miguel River and Red Mountain Creek drainages, in order to enhance water quality.  One performance objective of the RAP is to reduce zinc levels at a compliance point within San Miguel River segment 3b to 276 ug/l of dissolved or 336 ug/l of total zinc, on an average annual basis.  The Commission will review the appropriateness of the 190 ug/l dissolved zinc (chronic) standard for segments 3a and 3b in future rulemakings to assess whether it should be adjusted to reflect actual water quality achievable and the uses that are attainable in light of Idarado's remediation efforts.  In addition, five-year temporary modifications of 410 ug/l and 640 ug/l for dissolved zinc in segments 3a and 3b, respectively, to reflect ambient water quality are justified in light of the anticipated water quality enhancement resulting from Idarado's actions, and to coincide with the start of the compliance period under the RAP.  Nothing in this rulemaking is intended to adjust, modify, or abrogate the Consent Decree or RAP. 
f. 	New Water Supply Segments
In response to a request by HCCA and WSERC, the Commission has added a water supply classification, and corresponding numerical standards, to the following three segments: 
Upper Gunnison segments 8 (formerly 9) and 15 (formerly 16). 
North Fork segment 6. 
In each case, evidence was submitted that alluvial ground water hydrologically connected to these surface waters is used through domestic wells as a water supply.  For Upper Gunnison segment 8, the Commission also adopted temporary modifications for iron and manganese, in view of evidence that current levels of these constituents are elevated above table values. 
16. 	Other Proposals
EPA expressed concern in the hearing regarding whether documentation had been provided of an adequate “use attainability analysis” for segments whose classifications do not achieve the “fishable, swimmable” goals of the federal Clean Water Act.  Based on the information provided, the Commission has adopted the Division’s proposals for the waters in question.  The Commission encourages the Division to work with EPA to assure that adequate documentation of the Division’s use attainability analysis conclusions has been provided. 
HCCA and WSERC requested that the Commission take action in this hearing to prohibit future in-stream gravel mining.  The Commission has determined that this proposal is not relevant to the water quality designation, classification and standards issues raised in this hearing. 
35.24 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; JULY, 1997 RULEMAKING 
The provisions of sections 25-8-202 and 25-8-401, C.R.S., provide the specific statutory authority for adoption of the attached regulatory amendments.  The Commission also adopted, in compliance with section 24-4-103(4) C.R.S., the following statement of basis and purpose. 
BASIS AND PURPOSE: 
The Commission has adopted a revised numbering system for this regulation, as a part of an overall renumbering of all Water Quality Control Commission rules and regulations.  The goals of the renumbering are:  (1) to achieve a more logical organization and numbering of the regulations, with a system that provides flexibility for future modifications, and (2) to make the Commission’s internal numbering system and that of the Colorado Code of Regulations (CCR) consistent.  The CCR references for the regulations will also be revised as a result of this hearing. 
35.25 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; APRIL, 1998 RULEMAKING
The provisions of sections 25-8-202(1)(b) and (2); 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for the adoption of these regulatory amendments.  The Commission also adopted in compliance with section 24-4-103(4) C.R.S. the following Statement of Basis and Purpose. 
BASIS AND PURPOSE:
As the result of a June, 1997 rulemaking hearing considering numerous proposed revisions to Gunnison River Basin water quality standards, the Commission decided to apply recently revised aquatic life table value criteria for selenium (20 ug/l acute and 5 ug/l chronic) to many segments in the basin.  The basis for this action is discussed in paragraph 14 of the Statement of Basis and Purpose for that rulemaking (section 35.21).  However, it was later noticed that in that rulemaking the Commission inadvertently neglected to revise the listing of selenium table values contained in section 35.6(3) of the regulation.  In this rulemaking, the Commission is correcting the listing of selenium table values in section 35.6(3).  The Commission is also deleting reference to March 2, 1998 effective date for silver table values, since that date has now passed. 
35.26 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; DECEMBER, 1998 RULEMAKING
The provisions of sections 25-8-202(1)(b) and (2); 25-8-204; and 25-8-402 C.R.S. provide the specific statutory authority for the adoption of these regulatory amendments.  The Commission also adopted in compliance with section 24-4-103(4) C.R.S. the following Statement of Basis and Purpose. 
BASIS AND PURPOSE:
The Commission has recently approved a new schedule for triennial reviews of water quality classifications and standards for all river basins in Colorado.  In this hearing the Commission has extended the expiration dates of temporary modifications [and, for the Animas Basin, the effective dates of underlying standards] without substantive review, so that the next substantive review of the temporary modifications can occur as part of the overall triennial review of water quality standards for the particular watershed.  This will avoid the need for multiple individual hearings that would take staff resources away from implementation of the new triennial review schedule. 
35.71 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; JULY, 2001 RULEMAKING
The provisions of C.R.S. 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402; provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4) C.R.S. the following statement of basis and purpose. 
BASIS AND PURPOSE:
A. 	Resegmentation
Some renumbering and/or creation of new segments were adopted in the basin due to information which showed that: a) the original reasons for segmentation no longer applied; b) new water quality data showed that streams should be resegmented based on changes in their water quality; and/or c) certain segments could be grouped together in one segment because they had similar quality and uses.  The following changes were made: 
Upper Gunnison, Segment 13:  Woods Creek was separated into segments 13a and 13b to reflect the differences in recreation use. 
Upper Gunnison, Segments 20 and 21:  Lower portion of Indian Creek was moved from Segment 21 to Segment 20 to reflect the correct Uranium standard for that segment and lack of water supply use. 
Upper Gunnison, Segments 26, 27 and 28:  The Commission has decided to revise the segmentation of Segments 26, 27 and 28 of the Upper Gunnison River Basin based on the following rationale: 
• 	Existing ambient water quality conditions of waters flowing into or which are present within Curecanti National Recreation Area meet or are better than those required by The Basic Standards and Methodologies for Surface Water (5 CCR 1002-31) for Aquatic Life Cold 1. 
• 	These waters support an abundance of aquatic life.  Many waters support a fishery which includes but is not limited to Rainbow Trout and Brook Trout, and have been identified as a potential in supporting state threatened Colorado River Cutthroat trout.
• 	Blue Mesa, Morrow Point and Crystal reservoirs, as well as portions of the mainstem of the Gunnison River and Lake Fork of the Gunnison offer significant natural resource values dedicated to public use as Curecanti National Recreation Area.  These waters are classified as Aquatic Life Cold 1, Recreation 1 and it follows that the tributaries to these significant economic and natural resources have classifications as good or better. 
• 	This resegmentation provides a watershed approach to this portion of the Upper Gunnison basin. 
North Fork, Segment 2:  The segment description was modified to more accurately reflect the beginning of the mainstem of the North Fork of the Gunnison. 
North Fork, Segment 5:  The segment description was modified to include the entire Roatcap Creek system.  This change better reflects the aquatic life cold 1 uses of Roatcap Creek. 
Uncompahgre, Segment 3 and 4:  The segment descriptions were modified to clarify the transition point in the Uncompahgre River between cold (segment 3) and warm (segment 4) water aquatic life uses.  
Uncompahgre, Segment 4:  This segment was resegmented into segments 4a, 4b and 4c to account for significant differences in recreational activities which occur along the mainstem of the lower Uncompahgre River.  A UAA demonstrated that segment 4b (the Uncompahgre River from La Salle Road to Confluence Park) does not support recurring primary contact recreation. 
Uncompahgre, Segment 6:  Red Mountain Creek was separated into Segments 6a and 6b to reflect the differences in aquatic life uses.   
Uncompahgre, Segment 15:  Segment 15 was changed to 15a.  The mainstem of Dry Creek from the confluence of the East and West Forks to the boundary of the BLM land was removed from Uncompahgre segment 15a and placed into a new Uncompahgre segment 15b based on significant differences in recreational usage.  Dry Creek supports rafting and kayaking during some times of year; whereas. a UAA has demonstrated that primary contact recreation is unattainable in the rest of segment 15. 
Lower Gunnison, Segment 4:  The lakes and reservoirs from segment 4 were separated into a new segment 4b; along with Kannah Creek below the water supply diversion to reflect the recreation 1a uses of these waterbodies.  The remainder of segment 4 was renamed segment 4a. 
Lower Gunnison, Segment 11:  Doug Creek was added to the segment description to better reflect its cold water class 1 aquatic life use. 
B. 	Manganese 
The aquatic life manganese criterion was initially changed in the 1997 revisions to the Basic Standards (5 CCR 1002-31) from a single chronic dissolved criterion to acute and chronic hardness-based equations.  The equations were further modified in the 2000 revisions to the Basic Standards.  The new manganese acute and chronic equations were added as table value standards in 35.6(3).  As a result of the adoption of these new TVS, all segments classified for aquatic life use that had a chronic total recoverable manganese standard of 1,000 µg/L had the 1,000 standard stricken and replaced with Mn(ac/ch)=TVS.  
C. 	Selenium
The regulation in 35.6 (3) listed the table value standards for selenium as Acute=20 µg/L and Chronic=5 µg/L.  This was updated to reflect the existing acute and chronic criteria for selenium listed in the Basic Standards as Acute=18.4 µg/L and Chronic=4.6 µg/L which was adopted in 2000 by the Commission.  This change means that all segments with standards for selenium given as TVS now have these lower acute and chronic standards.   
The Commission adopted the table value standards for selenium and temporary modifications of existing ambient quality for selenium for Uncompahgre segment 12, Lower Gunnison segments 4a and 4b, and North Fork segment 6.  The Commission also extended the temporary modifications for selenium for Uncompahgre segments 4a, 4b, 4c, and 14 Lower Gunnison segment 2, and North Fork segment 5.  The temporary modifications were adopted or extended pursuant to section 31.7(3)(a)(iii) of the Basic Standards regulation, based on the fact that there is significant uncertainty as to the appropriate underlying selenium standard for these segments.  The reason for the adoption of the temporary modifications is noted in temporary modifications and qualifiers column of the table. 
Water quality monitoring has demonstrated a severe selenium problem in the Lower Gunnison and Uncompahgre River Basins.  The Gunnison River Selenium Task Force has been working since 1998 to evaluate the sources of selenium loading to the mainstem of the Uncompahgre and Gunnison rivers and methods to reduce those loads.  To date, the effort has focused on attempting to meet the standards in the Uncompahgre and Gunnison River mainstems.  Much of this effort has involved evaluating opportunities to reduce the loading, but not necessarily the concentrations, in the tributaries to both the lower Uncompahgre and lower Gunnison Rivers. 
Selenium reduction in the Uncompahgre and Gunnison River Basins is a very complex issue.  The tributaries to the Uncompahgre and Gunnison River pass through selenium-laden Mancos shale soils, and the extent to which the current levels of selenium are the result of natural sources, reversible activities, and/or irreversible activities is unknown at this time.  Therefore, it is not clear whether the table value standards are achievable in these segments.  The Commission does not intend its actions to in any way impede the efforts of the Selenium Task Force to reduce selenium loading in the Uncompahgre and Gunnison Rivers.  The Commission intends that the actions taken in this hearing will mark the beginning of a process to identify the appropriate long-term selenium standards for these segments.  It is expected that the efforts of the Selenium Task Force and others may result in the adoption of site-specific standards for selenium in some or all of the affected segments. 
D. 	Removal of Use Protected Designation
The Division proposed that a number of aquatic life class 2 waterbodies be assigned undesignated status under the state antidegradation regulation due to the presence of Colorado State species of special concern.  State regulations governing the “use-protected” designation allow this exception if the Commission determines that the waters are of exceptional ecological significance.  The Commission believes that a number of important issues have been raised in this hearing regarding when and how this exception should be applied, and that further examination of these issues should occur.  Nevertheless, for purposes of this hearing, the Commission, based upon a concern over the protection of classified uses and the absence of evidence of potential injury to permitted entities, has decided to accept the change to reviewable water status for the following: 
Lower Dolores, Segment 4 
Based upon representations made by certain parties to this rulemaking, the Commission endorses the formation of a workgroup to address the following topics and develop recommendations to be submitted to the Commission 
The relationship between the “exceptional ecological significance” exception to use-protected designations and the aquatic life class 2 basis for applying use-protected designations 
The need for and content of guidance to determine what water bodies are exceptionally ecologically significant 
The roles of a) water quality data; b) the nexus between water quality conditions and species decline, and c) other stressors, in using this exception 
The need for and nature of any amendments to the state antidegradation regulation if the presence of species of special concern constitute a basis for modification to the antidegradation designation of a water body. 
The above listed segments would then be reviewed in light of the work group recommendations in the next triennial review of these basins. 
The Commission urges that the work group process to address these issues move forward as expeditiously as possible.  The Commission intends that the actions taken in this rulemaking not serve in any way as a precedent with respect to decisions in future Commission rulemaking proceedings. 
E. 	Recreation Classifications/Fecal Coliform and E. Coli Standards
The biological standards were updated to include the dual standards for E. coli and fecal coliform, which were adopted by the Commission in the 2000 revisions to the Basic Standards.  As stated in the statement of basis for the Basic Standards revisions, the Commission intends that dischargers will have the option of either parameter being used in establishing effluent limitations in discharge permits.  In making section 303(d) listing decisions, in the event of a conflict between fecal coliform and E. coli data, the E. coli data will govern.  The Commission believes that these provisions will help ease the transition from fecal coliform to E. coli standards. 
In a continuation of the Commission’s efforts to comply with the requirements contained in the federal Clean Water Act that all waters of the nation should be suitable for recreation in and on the water (known as the “swimmable” goal), the Commission reviewed all Recreation Class 2 segments.  In Colorado, the “swimmable” goal translates into Recreation Class 1a, with the 200/100 ml fecal coliform and 126/100 ml E. Coli standard, and Class 1b with the 325/100 ml fecal coliform and 205/100 ml E. coli standard.  Class 1a indicates waters where primary contact uses have been documented or are presumed to be present.  Class 1b indicates waters where no use attainability analysis has been performed demonstrating that a recreation class 2 classification is appropriate, but for which no existing primary contact uses have been documented following a reasonable level of inquiry.  A Recreation Class 2 classification must be supported by a use attainability analysis that shows that there is not a reasonable potential for primary contact uses. 
There was considerable evidence and testimony submitted in this hearing regarding what activities should be considered primary contact recreation.  Section 31.13(1)(a) of the Basic Standards provides a non-exclusive list of primary contact activities.  In this hearing, much discussion focused on the issue of whether “child’s play” in streams that are too shallow to accommodate the primary contact uses listed in the Basic Standards should be considered a primary contact use.  The Commission does not believe that a theoretical potential for child’s play means that all streams should be classified Recreation Class 1a or 1b.  However, the Commission concludes that the evidence submitted demonstrates that there is a potential risk of ingestion of small quantities of water by children playing in relatively shallow streams, based on the hand-to-mouth pathway, which warrants Recreation Class 1 protection in appropriate circumstances as elaborated below.  Thus, such ingestion may occur in streams where whole body immersion is not likely.   
This does not mean, as suggested by some, that all water bodies would be reclassified as Recreation Class 1a or 1b based on some potential for child’s play.  Rather, the Commission intends that a stream should be classified Recreation Class 1a or 1b due to the presence or potential for child’s play only where the evidence demonstrates a likelihood of such activity on a frequently occurring basis.  Therefore, child’s play may be an appropriate basis for a Recreation Class 1a or 1b classification in a developed area where there is easy access to a stream for children and it is likely that children will desire to play in the stream; it may not be an appropriate basis for such classifications in areas where it is not expected that children will be playing in a stream on a frequently occurring basis.  Factors such as lack of adequate flow, excessive flows, remoteness from developed areas, physical limitations to access, steep banks, and visibly poor water quality may make it unlikely that child’s play will take place on a frequently occurring basis.  The Commission anticipates that these classification decisions will require case-by-case judgments until more experience is gathered with this issue. 
A recreation Class 1a or 1b classification of a segment is not intended to imply that the owner or operator of property surrounding any waterbody in a segment would allow access for primary contact recreation.  The application of recreation classifications to state waters pursuant to these provisions does not create any rights of access on or across private property for the purposes of recreation in or on such waters.  A recreation Class 1a classification is intended to only affect the use classification and water quality standards of a segment, and does not imply public or recreational access to waters with restricted access within a segment.   
For segments changing to recreation Class 1a because no evidence or inadequate evidence was submitted on the record about actual or potential recreational uses, the last paragraph of section 31.6(2)(b) will apply to future changes to the recreation classification where a proper showing is made through a use attainability analysis that a recreation Class 2 classification is appropriate, without application of the other downgrading criteria in this section.  Moreover, the Commission is relying in part on the testimony from EPA that completion of a use attainability analysis showing that a lower recreation classification is appropriate satisfies applicable downgrading criteria.  Based on these factors, the Commission intends that in a future rulemaking hearing, the test for adopting a recreation Class 2 classification would be the same as if it had been considered in this hearing. 
Upper Gunnison Basin 
Currently, there is a potentially explosive controversy escalating in the Upper Gunnison River Basin regarding public recreational floating use of waterways over private land.  This controversy has greatly elevated the concern over consequences of some of the recreation use classifications being proposed in connection with this triennial review.  The controversy also has greatly magnified the difficulty of conducting a water quality review process which is based on accurate, complete and neutral determinations of recreation uses of waterways. 
The Commission recognizes the potential for being drawn into this non-water quality related issue through the process of the triennial review of recreational use classifications.  The Commission intends that neither it nor the Division shall be drawn into the controversy. 
The Commission has accomplished the majority of the current review in the Upper Gunnison Basin but has taken no action on the recreational use classification or standards for the following segments: 
Upper Gunnison segments 5, 6a, 15, 16, 17, 18, 19, 21, 23, 24, and 26  (Under the National Park Service’s proposal segments 27, and 28 have been combined into segment 26) 
For these segments, the pre-existing recreation classifications and standards will continue.  The Commission believes that these classifications and standards are protective of the current uses. 
The Commission reiterates that a recreational use attainability analysis is required to support adoption of a Recreation 2 classification.  Continuation of the current classification of Recreation 2, with a 200/100ml fecal coliform standard until the next triennial review does not represent a decision that Recreation 2 or 200 fecal coliform are the ultimate classification or standards for these stream segments, or eliminate the need to conduct recreational use attainability analyses for any Class 2 stream segments in the future.  In addition, the Commission agrees that it would be appropriate for the Basic Standards Implementation work group to address these and similar issues before the next Basic Standards rulemaking. 
Other Gunnison River Segments 
Based on the information received that showed Recreation Class 1a uses are in place or are presumed to be present in at least a portion of the segment, the Commission changed the following segments from Class 2 to Class 1a with a 200/100 ml fecal coliform and 126/100 ml E. coli standard: 
Upper Gunnison, Segments:  11, 12, 13a, 20, 22, 31 
Uncompahgre, Segments:  4a, 4c, 5,15b 
Lower Gunnison, Segments:  3, 4b, 8, 11 
San Miguel, Segments:  2, 3a, 6a, 6b, 7a, 7b, 12 
Lower Dolores, Segments:  3, 4, 5 
The following segments with existing Recreation Class 1 classifications were changed to Class 1a: 
Upper Gunnison, Segments:  1, 2, 3, 4, 6b, 7, 8, 9, 10, 14, 25, 29, 30, 32 
North Fork, Segments:  1, 2, 4, 7 
Uncompahgre, Segments:  1, 3, 14 
Lower Gunnison, Segments:  1, 2, 5, 6, 10, 13 
San Miguel, Segments:  1, 3b, 4, 5, 8, 9, 10, 11 
Lower Dolores, Segments:  1, 2 
Based on the information received, where a reasonable level of inquiry failed to identify any existing class 1 uses of the waters in these segments, the Commission changed the following segments to Class 1b with a 325/100 ml fecal coliform and 205/100 ml E. coli standard: 
Upper Gunnison, Segment:  13b  
North Fork, Segments:  5, 6  
Uncompahgre, Segments:  9  
Lower Gunnison, Segments:  7, 12 
For the following segments, the Commission adopted seasonal recreation classifications, based on evidence differences in actual or potential uses at different times of the year: 
North Fork, Segment 3:	Class 1a, April 1 through September 30 
Class 2, October 1 through March 31 
Uncompahgre, Segments 10, 11:	Class 1b, May 1 through October 31
Class 2, November 1 through April 30 
Lower Gunnison, Segment 9:	Class 1a, April 1 through October 31
Class 2, November 1 through March 31 
The following segments retained their Recreation Class 2 classification with 2,000/100ml fecal coliform and 630/100 ml E. coli standards after sufficient evidence was received that a Recreation Class 1a use was unattainable. 
Uncompahgre River, Segments:  2, 4b, 6a, 6b, 7, 8, 12, 13, 15a 
Lower Gunnison, Segment:  4a 
The classifications for Uncompahgre segments 2, 7 and 8 are based upon low flows, cold temperatures, limited access and streambed characteristics that prevent primary contact recreation.  The classifications for Uncompahgre segments 12, 13 and 15a and Lower Gunnison segment 4a are based upon low flows, limited access and streambed characteristics that prevent primary contact recreation.  The classification for Uncompahgre 4b is based upon low flows and the presence of numerous major irrigation diversion structures which are hazardous and preclude primary contact recreation.  The classifications for Uncompahgre segments 6a and 6b are based upon the gradient and size of the streambed, cold temperatures, and the fact that the allowable pH in this segment precludes primary contact recreation. 
F. 	Aquatic Life Segments without Full Standards
The Commission reviewed information regarding Aquatic Life Class 2 segments where the full set of inorganic aquatic life protection standards have not been applied.  Generally, these are dry segments with only rudimentary aquatic life.  The Commission’s policy has been that rather than adopt the full set of inorganic standards for these segments, standards for dissolved oxygen, pH and fecal coliform provide sufficient protection.   
Segments where investigation showed that aquatic life was present were upgraded with the addition of the full suite of inorganic standards.  These segments are:  
Upper Gunnison, Segments:  13, 15, 27 
North Fork, Segment:  6 
Uncompahgre, Segments:  6a, 10, 12 
Lower Gunnison, Segment:  4 
San Miguel, Segment:  12 
G. 	Ambient Quality-Based Standards
There are several segments in the Gunnison Basin that contain standards based on existing ambient quality.  Ambient standards are adopted where natural or irreversible man-induced conditions result in water quality levels higher (i.e. worse)  than table value standards.  EPA had requested that the Commission review the information that is the basis for these standards as well as any new information that would indicate whether they are still appropriate, need to be modified, or should be dropped.  The Division reviewed the reason for the ambient standards and provided testimony that justified ambient standards being retained without adjustment on the following segments: 
Upper Gunnison, Segments:  10(Pb), 20 
San Miguel, Segment:  10 
The Division reviewed the information about ambient water quality levels and provided testimony that justified revising or adopting the ambient standards on the following segments: 
Upper Gunnison, Segments:  11, 12, 15 
Uncompahgre, Segments:  3, 4, 7, 11, 12 
Lower Gunnison, Segment:  2 
San Miguel, Segment:  8 
Ambient standards were removed from the following segments due to new data and/or changes to the basic standards which indicated ambient standards were no longer appropriate: 
Upper Gunnison, Segments:  10(Zn), 12, 17, 18, 21, 30 
North Fork Gunnison, Segment:  4 
Uncompahgre, Segment:  2 
Lower Gunnison, Segment:  2 
San Miguel, Segment:  6b 
H. 	Temporary Modifications
There were several segments which had temporary modifications that were reviewed, and decisions were made as to delete or to extend them, either as is or with modification of the numeric limits.  
Upper Gunnison, Segment 8:  Slate Creek:  This segment had temporary modifications for iron and manganese set at existing ambient quality.  The revisions to the Water Supply standards resolved this issue and therefore the temporary modification is no longer needed.  The temporary modification was deleted. 
North Fork, Segment 5:  Tribs to North Fork:  This segment has a temporary modification for selenium.  The Selenium Task Force is studying this issue.  The expiration date of the temporary modification was extended from 8/30/02 to 12/31/06 to coincide with the next triennial review.   
Uncompahgre, Segment 4a, 4b, 4c:  Uncompahgre River, Montrose to Gunnison River: This segment has a temporary modification for selenium.  The Selenium Task Force is studying this issue.  The expiration date of the temporary modification was extended from 8/30/02 to 12/31/06 to coincide with the next triennial review.  This segment also had a temporary modification for fecal coliform which was deleted.   
Uncompahgre, Segment 14:  Sweitzer Lake:  This segment has a temporary modification for selenium.  The Selenium Task Force is studying this issue.  The selenium temporary modification value was changed to reflect current conditions and the expiration date was extended from 8/30/02 to 12/31/06 to coincide with the next triennial review.  
Lower Gunnison, Segment 2:  Gunnison River, Uncompahgre to Colorado Rivers:  This segment has a temporary modification for selenium.  The Selenium Task Force is studying this issue.  The selenium temporary modification value was changed to reflect current conditions and the expiration date was extended from 8/30/02 to 12/31/06 to coincide with the next triennial review.
Lower Gunnison, Segment 9:  Fruitgrowers Reservoir:  This segment has temporary modifications for fecal coliform and unionized ammonia.  The Division and other agencies are studying the reservoir.  Data indicates that the underlying standards are attained.  The temporary modifications were deleted.  A temporary modification for dissolved oxygen was adopted with an expiration date of 12/31/06.  
San Miguel, Segment 3a: San Miguel River, Upper portion to Marshall Creek:  This segment has a temporary modification for zinc.  Remedial work is currently conducted in the upper part of the basin.  The expiration date of the temporary modification was extended from 6/30/02 to 12/31/06 to coincide with the next triennial review. 
San Miguel, Segment 3b: San Miguel River, Marshall Creek to South Fork:  This segment has temporary modifications for zinc, cadmium and manganese.  Data indicates that the underlying standards are attained for cadmium and manganese.  The temporary modifications for cadmium and manganese were deleted.  The zinc temporary modification value was changed to reflect current conditions and the expiration date was extended from 6/30/02 to 12/31/06 to coincide with the next triennial review. 
San Miguel, Segment 4, San Miguel River, South Fork to Naturita Creek:  This segment has a temporary modification of the temperature standard from the Power Plant Bridge to Naturita Creek, of 28o C for July, August and September, which is set to expire 12/31/2006.  The temporary modification is provided to allow time for Tri-State Generation and Transmission Association to participate in a work group to address the statewide implementation of the narrative and numeric temperature standards. 
There were several segments where temporary modifications that reflect current ambient conditions were adopted.  Temporary modifications were set to expire on 12/31/06 to coincide with the next triennial review.  The segments and the constituents are:  
Upper Gunnison, Segment 10:  cadmium, copper, and zinc 
Upper Gunnison, Segment 11:  cadmium and zinc 
Upper Gunnison, Segment 12:  zinc 
North Fork, Segment 6:  selenium 
Uncompahgre, Segment 12:  selenium 
Lower Gunnison, Segment 4:  selenium 
Lower Gunnison, Segment 7:  selenium and iron 
San Miguel, Segments 6a and 6b:  zinc 
San Miguel Segment 7b:  lead 
I. 	Organic Chemical Standards
The organic chemical standards were updated to include changes adopted by the Commission in the 2000 revisions to the Basic Standards (see 31.11 in Regulation No. 31).  “Water + Fish” organic chemical standards are presumptively applied to all Aquatic Life Class 1 streams which also have a Water Supply classification, and are applied to Aquatic Life Class 2 streams which also have a Water Supply classification, on a case-by-case basis.  The  “Fish Ingestion” organic chemical standards are presumptively applied to all Aquatic Life Class 1 streams which do not have a Water Supply classification, and are applied to aquatic life class 2 streams which do not have a Water Supply classification, on a case-by-case basis.  Existing site-specific applications of additional organics (as noted in the Qualifier column of Table 35.7) were modified to conform to this change.   
Information was reviewed regarding Aquatic Life Class 2 segments that have fish that are presently being taken for human consumption or have fisheries that would indicate the potential for human consumption.  That information showed that four additional segments had the potential for consumption of fish.  These waterbodies were designated to receive the full protection of numeric Water + Fish or Fish Ingestion organic standards: 
Fish Ingestion:  Upper Gunnison Segment 13 
Water + Fish:  Upper Gunnison Segment 17, North Fork Segment 6, and Uncompahgre Segment 10 
J. 	Water Supply Classification
These segments had the Water Supply classification added to them.  The associated water supply standards will now apply to segments: 
Upper Gunnison, Segments:  13a, 13b Uncompahgre, Segment:  10 Lower Gunnison, Segment:  4 San Miguel, Segment:  12 
The Commission rejected a proposal by the High Country Citizens Alliance that a water supply classification be added to Upper Gunnison segment 12, based on the presence of a private water well near this segment of the stream.  The Commission does not believe that adequate evidence was provided that the quality of water in segment 12 influences the quality of water in this well. 
K. 	Modification of Water Supply Standards
Water supply standards were modified to conform to the changes made by the Commission in the 2000 revisions to the Basic Standards (see Regulation No. 31 at section 31.11(6)).  The Commission modified the water supply standards for iron, manganese, and sulfate that are based on secondary drinking water standards (based on aesthetics as opposed to human-health risks).  The numeric values in the tables were changed to Fe(ch) = WS (dis), Mn(ch) = WS (dis), and SO4 = WS.  These abbreviations mean that for all surface waters with an actual water supply use, the less restrictive of the following two options shall apply as numerical standards, as discussed in the Basic Standards and Methodologies at section 31.11(6): either (i)  existing quality as of January 1 2000; or  (ii) Iron = 300 µg/L (dissolved); Manganese = 50 µg/L (dissolved); Sulfate = 250 mg/L (dissolved).  For all surface waters with a “Water Supply” classification that are not in actual use as a water supply, no water supply standards are applied for iron, manganese or sulfate, unless the Commission determined as the result of a site-specific rulemaking hearing that such standards are appropriate. 
L. 	Agriculture Classifications
There is one segment in the Gunnison River Basin that was not correctly classified for Agricultural use.  The Agricultural use classification was adopted for San Miguel, Segment 3b.  
M. 	Agriculture Standards
Numeric Standards to protect Agricultural Uses were adopted for the following segments: 
Upper Gunnison, Segments:  6a, 31 
Lower Gunnison, Segment  12 
Lower Dolores, Segment  3 
N. 	Other Site-Specific Revisions 
The Commission corrected several typographical and spelling errors, and clarified segment descriptions.   
The following aquatic life classifications were upgraded from class 2 to class 1 based on information presented that showed diverse aquatic communities in these segments.  
Lower Gunnison, Segment  8 
Lower Gunnison, Segment 6 was changed from aquatic life class 2 warm to class 1 cold, based on information received about the aquatic community that includes trout species. 
Aquatic life cold 2 use classifications were added to Upper Gunnison Segment 13 and Uncompahgre Segments 6a and 6b, based on information that an aquatic community is in place in these segments. 
PARTIES TO THE RULEMAKING HEARING 
1.	Animas River Stakeholders Group 
2.	Colorado Wild, San Juan Citizen’s Alliance, Sierra Club-Rocky Mountain Chapter, Colorado Environmental Coalition and The Wilderness Society  
3. 	U.S. Department of the Interior, Bureau of Land Management  
4. 	Sunnyside Gold Corporation  
5. 	The Southwestern Water Conservation District 
6. 	Silver Wing Company, Inc. 
7. 	U.S. Department of Agriculture Forest Service  
8. 	Shenandoah Mining Company Incorporated 
9. 	Town of Silverton  
10. 	Pagosa Area Water and Sanitation District 
11. 	Peter Butler  
12. 	U.S. Department of the Interior National Park Service  
13. 	Climax Molybdenum Company 
14. 	Tri-State Generation and Transmission Association, Inc. 
15. 	Town of Olathe  
16. 	The Board of County Commissioners of the County of Gunnison 
17. 	Gunnison County Stockgrowers Association, Inc.  
18. 	High Country Citizens’ Alliance and Western Slope Environmental Resource Council 
19. 	The City of Grand Junction 
20. 	Homestake Mining Company  
21. 	The Board of County Commissioners of the County of San Miguel 
22. 	Mt. Crested Butte Water and Sanitation District 
23. 	Colorado River Water Conservation District 
24. 	Town of Cedaredge 
25. 	The Board of County Commissioners of the County of Mesa 
26. 	The Uncompahgre Valley Water Users Association 
27. 	Umetco Minerals Corporation 
28. 	The Colowyo Coal Company, L.P. 
29. 	The Uncompahgre Valley Association 
30. 	Town of Crested Butte 
31. 	The City of Delta 
32. 	Trapper Mining, Inc. 
33. 	The Colowyo Coal Company, L.P. 
34. 	The City of Grand Junction 
35. 	Colorado River Water Conservation District 
36. 	Yellow Jacket Water Conservation District  
37. 	The Town of Meeker  
38. 	The City of Fruita 
39. 	Exxon Mobil Corporation 
40. 	Shell Frontier Oil & Gas Inc. 
41. 	The Board of County Commissioners of the County of Mesa 
42. 	American Soda, LLP 
43. 	The Rio Blanco Water Conservancy District 
44. 	Colorado Division of Wildlife 
45. 	The Northern Colorado Water Conservancy District and its Municipal Subdistrict 
46. 	Upper Gunnison River Water Conservancy District  
47. 	U.S. EPA Region  
48. 	Ralph E. Clark III  
49. 	U.S. Department of the Interior, Fish and Wildlife Service 
35.72 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; DECEMBER 12, 2005 RULEMAKING EFFECTIVE MARCH 2, 2006
The provisions of C.R.S. 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402; provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4) C.R.S. the following statement of basis and purpose. 
BASIS AND PURPOSE: 
In the process of digitally mapping the segments in the Gunnison and Lower Dolores River Basins, the Division discovered errors and inconsistencies between segment descriptions.  To resolve these issues the Commission adopted changes in the following segment descriptions: 
Upper Gunnison segments 3, 10 and 32 
Lower Gunnison segments 11 and 12 
San Miguel segments 2 and 10 
Lower Gunnison segment 11 was split into segments 11a and 11b:  Segment 11b was added to identify the portion of the segment within the West Elk Wilderness Area. 
35.21 	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE; JUNE 12, 2006 RULEMAKING; ADOPTED AUGUST 14, 2006; EFFECTIVE JANUARY 1, 2007
The provisions of C.R.S. 25-8-202(1)(a), (b) and (2); 25-8-203; 25-8-204; and 25-8-402; provide the specific statutory authority for adoption of these regulatory amendments.  The Commission also adopted in compliance with 24-4-103(4) C.R.S. the following statement of basis and purpose. 
BASIS AND PURPOSE:
A. 	Waterbody Segmentation
Some renumbering and/or creation of new segments in the basin was made due to information which showed that:  a) the original reasons for segmentation no longer applied; b) new water quality data showed that streams should be resegmented based on changes in their water quality; and/or c) certain segments could be grouped together in one segment because they had similar quality and uses.  The following changes were made: 
Upper Gunnison River Basin segment 29b was created for Lake San Cristobal. 
Uncompahgre River Basin segment 3b was created for Ridgway Reservoir. 
Waters within the Redwell Basin, tributary to Oh-Be-Joyful Creek, were moved to Upper Gunnison River Basin segment 10 to maintain water quality relationships of Oh-Be-Joyful Creek basin below the wilderness area boundary. 
Red Mountain Creek tributaries Corkscrew and Champion basins were added to Uncompahgre River Basin segment 6b (Red Mountain Creek) to maintain water quality relationships of the drainage. 
Pryor Creek and West Fork Spring Creek were added to Uncompahgre River Basin segment 13 because of similar water quality and uses with the existing segment. 
San Miguel River Basin segment 4 was resegmented into segments 4a and 4b. 
Lower Dolores River Basin segment 3b was created for the waters within the Sinbad Valley (Salt Creek). 
B. 	Revised Aquatic Life Use Classifications  
The Commission reviewed information regarding existing aquatic communities.  The Aquatic Life Use classifications were changed for several segments based on the presence of Colorado Cutthroat Trout, current temperature data and deleted for one segment.  The following changes were made: 
Aquatic Life Use changed from Cold 2 to Cold 1 to reflect the presence of Colorado Cutthroat Trout, a species of special concern: 
Upper Gunnison River Basin segment 17 
Uncompahgre River Basin segment 13 
Aquatic Life Use changed from Cold to Warm based on temperature data and aquatic life species present: 
Lower Gunnison River Basin segment 2 
Deletion of the Aquatic Life Use based on water quality and aquatic life sampling and the preparation of a use attainability analysis: 
Uncompahgre River Basin segment 6b. 
C. 	Recreation Classifications and Standards
As part of the Basic Standards hearing of 2005, recreation classifications were revised into four new classifications.  The Commission reviewed the previous segment classifications (1a, 1b and 2) and determined the appropriate new classification based on classification criteria presented as part of the Basic Standards Hearing, use attainability analyses or other basis.  In addition, during the 2005 Basic Standards Hearing, the transition from the use of the fecal coliform standard to an E. coli standard was completed.  Fecal coliform criteria were deleted from the numeric standards. 
Based on the information that showed existing primary contact recreation use is in place in at least a portion of the segment, the Commission changed the following segments from Recreation Class1a to Recreation Class E with a 126/100 ml E. coli standard: 
Upper Gunnison River Basin segments:  1, 2, 3, 4, 5, 6b, 7, 8, 9, 10, 11, 12, 13a, 14, 20, 22, 25, 29a, 29b, 30, 31 and 32 
North Fork of the Gunnison River Basin segments:  1, 2, 4 and 7 
Uncompahgre River Basin segments:  1, 3a, 4a, 4c, 5, 6b, 13, 14 and 15b 
Lower Gunnison River Basin segments:  1, 2, 3, 4b, 5, 6, 8, 10, 11a, 11b and 13 
San Miguel River Basin segments:  1, 2, 3a, 3b, 4, 5, 6a, 6b, 7a, 7b, 8, 9, 10, 11 and 12 
Lower Dolores River Basin segments:  1, 2, 3a, 4 and 5 
The following segments were converted from Recreation Class 1b to Recreation Class P with a 205/100 ml E. coli standard: 
Upper Gunnison River Basin segment13b 
North Fork of the Gunnison River segments 5 and 6 
Uncompahgre River Basin segment 9 
Lower Gunnison River Basin segments 7 and 12 
The following segment was converted from Recreation Class 1 to Recreation Class U: 
Upper Gunnison River Basin segment 6a 
The following segments were converted from Recreation Class 2 to Recreation Class U.  These segments include: 
Upper Gunnison River Basin segments 16, 17, 18, 19, 21, 23, 24 and 26.  The E. coli standard for these segments were 126/100 ml and were not changed. 
Upper Gunnison River Basin segment 15 had a fecal coliform standard of 2000/100 ml and was changed to be consistent with the use at 126/100ml E. coli. 
Based on review of existing Use Attainability Analyses showing that primary contact recreation is not attainable, the following segments were converted to Recreation Class N classification with 630/100 ml E. coli standard: 
Uncompahgre River Basin segments 2, 4b, 6a, 7, 8, 12 and 15a 
Lower Gunnison River Basin segment 4a 
The following segments with seasonal Recreation Class 1a/Recreation Class 2 classification were converted to Class E/Class N: 
North Fork of the Gunnison River Basin segment: 3 
Lower Gunnison River Basin segment 9 
The following segment with seasonal Recreation Class 1a/Recreation Class 1b classification was converted to Class E/Class P: 
Uncompahgre River Basin segment 10 
The following segment with seasonal Recreation Class 1b/Recreation Class 2 classification was converted to Class P/Class N: 
Uncompahgre River Basin segment 11 
D. 	Addition of Water Supply Use Classification and Standards
Based on review of information regarding the location of public water supplies, a water supply classification and standards were added Uncompahgre River Basin segment 3a. 
E. 	Agriculture Standards
Numeric Standards to protect Agricultural Uses were adopted for the following segments: 
Uncompahgre River Basin segment: 6a 
San Miguel River Basin segments: 3a, 6a and 6b 
F.  	Changes to Antidegradation Designation
Outstanding Waters Designation:  Based on evidence that shows the water quality meets the requirements of 31.8(2)a, the OW designation was added to the following segment:  Upper Gunnison River Basin segment 1 was modified to incorporate the waters within the Powderhorn Wilderness Area. 
Decoupling Cold 2 and UP:  As part of the Basic Standards hearing of 2005, the Commission eliminated the direct linkage between cold-water aquatic life class 2 and the use-protected designation.  Therefore, all cold-water aquatic life class 2 segments that are use-protected were reviewed to determine if that designation is still warranted.  The following segments are now reviewable: 
Upper Gunnison River Basin segments:  6a, 13a, 13b, 15 and 17 
Uncompahgre River Basin segments:  6a, 7, 8, 9, 10, and 13 
Lower Gunnison River Basin segment:  7. 
San Miguel River Basin segment:  12. 
Decoupling Aquatic Life Warm 2 and UP:  Also as part of the Basic Standards hearing of 2005, the Commission decided that the presence of a warm water class 2 classification would still be a presumptive basis for applying a use-protected designation; however, that presumption can be overcome if there is data showing that the water is of high quality.  Therefore, the Commission reviewed all warm water class 2 segments to determine if the use protected designation is still warranted.  No Regulation 35 aquatic life warm 2 segments were changed from use-protected to reviewable. 
G. 	Addition of Aquatic Life Standards
Based on water quality sampling data and aquatic life information, aquatic life numeric standards were added to Upper Gunnison River Basin segment 6a. 
H. 	Ambient Quality-Based Standards
There are several segments in the Basins that are assigned standards based on existing ambient water quality.  Ambient standards are adopted where natural or irreversible man-induced conditions result in exceedances of table value standards.  The Commission reviewed the information that is the basis for these standards as well as any new information that would indicate whether they are still appropriate, need to be modified, or should be dropped.  The Commission did not adopt any changes to the ambient quality-based standards. 
I. 	Aquatic Life Ammonia Standards
At the June 2005 Basic Standards rulemaking, the Commission adopted the 1999 Update of Ambient Water Quality Criteria for Ammonia (US EPA, Office of Water, EPA-822-R-99-014, December 1999) as the numeric ammonia criteria for Colorado.  These new criteria are in the form of total ammonia rather than un-ionized ammonia.  The Commission modified the ammonia equations in 35.6(3) and footnotes to conform to Regulation No. 31.  In cases where dischargers need time beyond one permit term to assure compliance with new permit limits, temporary modifications have been adopted.  These are listed below in the temporary modification section. 
J. 	Aquatic Life Metals Standards
New Table Value Standards:  As part of the Basic Standards hearing of 2005, new zinc and cadmium table values were adopted.  The acute and chronic zinc and cadmium equations in 35.6(3) were modified to conform to Regulation No. 31. 
Site-Specific Zinc Standards for Sculpin:  In low hardness situations (hardness below 113 mg/l CaCO3) the new zinc equation is not protective of sculpin, a native west-slope fish species.  The Commission adopted sculpin-specific zinc equation as site-specific standards for the following segments that are inhabited by sculpin that also have low hardness: 
Upper Gunnison River Basin segments:  2, 3, 4, 6a, 7, 15, 16, 19, 22, 23, 29a, 30 and 32
North Fork of the Gunnison River Basin segments:  1, 2 and 4 
Uncompahgre River Basin segments:  5 and 6a 
Lower Gunnison River Basin segment:  8 |
San Miguel River Basin segments:  1 and 2 
K. 	Arsenic Standards
For arsenic, each use (except recreation) has a different arsenic (“As”) value, including Fish Ingestion (FI) and Water Plus Fish (W+F).  In different combinations of uses, different values become the most limiting.  In order to eliminate the confusion, the Commission added the operative value to the individual segments.  The following matrix displays the most limiting arsenic criteria. 
Most Limiting Arsenic Criteria 
Depending on the Possible Combinations of Uses and Qualifiers 
If the Use Classifications were:	These Arsenic Standards were Applied (dissolved unless otherwise noted)	
Class 1 aquatic life, water supply	As(ac) = 340, As(ch) = 0.02(trec)	
Class 2 aquatic life (water + fish standards), water supply	As(ac) = 340, As(ch) = 0.02(trec)	
Class 2 aquatic life (no fish ingestion standards), water supply	As(ac) = 340, As(ch) = 0.02 – 10(trec)	
Class 1 aquatic life	As(ac) = 340, As(ch) = 7.6(trec)	
Class 2 aquatic life (fish ingestion standards)	As(ac) = 340, As(ch) = 7.6(trec)	
Class 2 aquatic life (no fish ingestion standards), agriculture	As(ac) = 340, As(ch) = 100(trec)	
Agriculture only	As(ch) = 100 (trec)	
Water supply only	As(ch) = 0.02 – 10(trec)	
L. 	Uranium Standards 
Uranium standards were added for segments that flow near uranium-bearing rock formations.  The Uranium standard was added to: 
Lower Gunnison River Basin segments:  5 and 6 
San Miguel River Basin segments:  5 and 12 
Lower Dolores River Basin segments:  1, 2, 3a, 4 and 5 
M. 	Temporary Modifications
All temporary modifications were re-examined to determine whether to delete the temporary modification or to extend them, either as existing or with modifications of the numeric standards.  Because of the June 2005 changes to Regulation No. 31, temporary modifications were not automatically extended if non-attainment persisted. 
The following segments had temporary modifications which are being removed because current ambient conditions are meeting the underlying standards: 
Uncompahgre River Basin segment 4a (Selenium). 
Temporary modifications were removed for the following segments though the water quality standards were not being met. 
Upper Gunnison River Basin segment:  10 
Lower Gunnison River Basin segment:  9 
San Miguel River Basin segments:  6a, 6b and 7b. 
The following segments have new or extended temporary modifications.  As specified in 61.8(2)(c)(iii) (the Permit Rules, Regulation No 61), where a temporary modification has been adopted, limits in permits are to be set based on the temporary modification and the provision strictly limiting the loading from the facility does not apply.  These temporary modifications will be subject to review and rulemaking for the two years before their scheduled expiration in order to track progress towards the full attainment of water body standards and uses. 
Upper Gunnison River Basin segment 8:  Cd(ch) = 0.4, expiration date of 12/31/2011.  This temporary modification is intended to allow the Town of Crested Butte Wastewater Treatment Plant adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Upper Gunnison River Basin segment 12:  Cd(ch) = 2.3, Zn(ch)= 518, expiration date of 12/31/2011.  This temporary modification is intended to allow the Keystone Mine adequate time to assess any potential changes to its discharge permit.  The need for these temporary modifications will be reviewed in 2009 and 2010. 
Upper Gunnison River Basin segment 16:  Zn(ch) = 11.9, expiration date of 12/31/2011.  This temporary modification is intended to allow the North Elk Meadows HOA Wastewater Treatment Facility adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
North Fork of the Gunnison River Basin segment 3:  Se(ch) = 5.7, expiration date of 12/31/2011.  This temporary modification is intended to allow multiple dischargers adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
North Fork of the Gunnison River Basin segment 5:  Se(ch) = existing ambient quality, expiration date of 12/31/2011.  This temporary modification is intended to allow multiple dischargers adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
North Fork of the Gunnison River Basin segment 6b:  Fe(ch)(Trec)= existing ambient quality, Se(ch) = existing ambient quality, expiration date of 12/31/2011.  This temporary modification is intended to allow multiple dischargers adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Uncompahgre River Basin segment 3a:  Cd(ch)=1.1, Fe(Trec) = 1673, expiration date of 12/31/2011.  This temporary modification is intended to allow multiple dischargers adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Uncompahgre River Basin segment 4a:  NH3(ac/ch)=TVS(old) expiration date of 12/31/2011.  This temporary modification is intended to allow the City of Montrose and the West Montrose Sanitation District Wastewater Treatment Plant adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Uncompahgre River Basin segment 4b:  Se(ch) = 20, expiration date of 12/31/2011.  This temporary modification is intended to allow multiple dischargers adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Uncompahgre River Basin segment 4b:  NH3(ac/ch)=TVS(old) expiration date of 12/31/2011.  This temporary modification is intended to allow the Town of Olathe Wastewater Treatment Plant adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Uncompahgre River Basin segment 4c:  Se(ch) = 20, expiration date of 12/31/2011.  This temporary modification is intended to allow the Gunnison Basin Selenium Task Force and the Colorado River Water Conservation District adequate time to assess any potential changes.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Uncompahgre River Basin segment 12:  Se(ch) = existing ambient quality, expiration date of 12/31/2011.  This temporary modification is intended to allow the Gunnison Valley Selenium Task Force adequate time to assess any potential changes.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Lower Gunnison River Basin segment 2:  Se(ch) = 8.4, expiration date of 12/31/2011.  This temporary modification is intended to allow the Gunnison Valley Selenium Task Force adequate time to assess any potential changes.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Lower Gunnison River Basin segment 2:  NH3(ac/ch)=TVS(old) expiration date of 12/31/2011.  This temporary modification is intended to allow the City of Delta Wastewater Treatment Plant adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Lower Gunnison River Basin segment 4a:  Se(ch) = existing ambient quality, expiration date of 12/31/2011.  This temporary modification is intended to allow the Gunnison Valley Selenium Task Force adequate time to assess any potential changes.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Lower Gunnison River Basin segment 4a:  NH3(ac/ch)=TVS(old) expiration date of 12/31/2011.  This temporary modification is intended to allow the Town of Cedaredge Wastewater Treatment Plant adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Lower Gunnison River Basin segment 4b:  Se(ch) = existing ambient quality, expiration date of 12/31/2011.  This temporary modification is intended to allow the Gunnison Valley Selenium Task Force adequate time to assess any potential changes.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Lower Gunnison River Basin segment 7:  Se(ch) = 9.3 and Fe(ch)(Trec)= 2650, expiration date of 12/31/2011.  This temporary modification is intended to allow the Gunnison Valley Selenium Task Force adequate time to assess any potential changes and to allow dischargers any potential changes to their permits.  This need for this temporary modification will be reviewed in 2009 and 2010. 
San Miguel River Basin segment 2:  Cd(ch) = 0.6, expiration date of 12/31/2011.  This temporary modification is intended to allow the Telluride Water Treatment Plant adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
San Miguel River Basin segment 3b:  Cd(ch) = 0.7, Zn(ch) = 198 expiration date of 12/31/2011.  This temporary modification is intended to allow the Telluride Wastewater Treatment Plant adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
San Miguel River Basin segment 4b:  Temperature = 26.3°C MWAT below the mixing zone of the Tri-State Generation and Transmission Nucla Power Station from 6/1 to 9/30, expiration date of 12/31/2011.  This temporary modification is intended to allow Tri-State Generation and Transmission adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010.  Further discussion of this temporary modification is found in Section N. Other Site-Specific Revisions. 
San Miguel River Basin segment 5:  NH3(ac/ch)=TVS(old) expiration date of 12/31/2011.  This temporary modification is intended to allow the Naturita Wastewater Treatment Plant adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
Lower Dolores River Basin segment 2:  NH3(ac/ch)=TVS(old) expiration date of 12/31/2011.  This temporary modification is intended to allow the Southwest Mesa County Rural Public Improvement District (Gateway) adequate time to assess any potential changes to its discharge permit.  This need for this temporary modification will be reviewed in 2009 and 2010. 
For segments with multiple streams or “all tributary” segments the Division in setting temporary modifications should use the narrative statement “existing ambient quality” to avoid confusion with multiple sampling locations. 
N. 	Other Site-Specific Revisions 
1. 	Lower Gunnison segment 4c:  The Commission made the decision to resegment and change the recreation use of Red Rock Creek within the Black Canyon of the Gunnison National Park.  This portion of Rock Creek was previously included in an all tributaries segment.  The recreation use was changed from secondary contact to existing primary contact use.  This change was based on evidence of greater public use to the area through recently opened public access. 
2. 	North Fork segment 6:  North Fork Segment 6 of the Gunnison River was refined to better define the “all tributaries” segment.  Segment 6b was created with the existing use classifications based on 1) the presence of surface water and ground water under the influence of surface water that is used for water supply and 2) the presence of “fish of catchable size and that are normally consumed.”  Waterbodies with these uses were identified in this segment.  The water supply use and the Water+Fish qualifier were removed from segment 6a since waterbodies with these uses were included in segment 6b. 
3. 	San Miguel segment 4:  The Commission resegmented San Miguel segment 4 into segments 4a and 4b with a new segment boundary at the CC Ditch.  The decision was made to retain Cold Water Class 1 Aquatic Life in Segment 4a and to reclassify Segment 4b as Cold Water Class 2 based on dewatered conditions below the CC Ditch. The temperature standard of 20°C is applied to segments 4a and 4b.  A new temporary modification has been applied to segment 4b, below the mixing zone of Tri-State Generation and Transmission Nucla Power Station. 
The Commission adopted a temporary modification for temperature in the lower portion of Segment 4b of 26.3 °C, as a maximum weekly average temperature ("MWAT") from 6/1 to 9/30, to expire 12/31/2011.  This temporary modification is adopted pursuant to Regulation 31.7(3)(a)(iii) because there is significant uncertainty regarding the appropriate long term underlying temperature standard. 
There is uncertainty associated with the underlying standard in the lower portion of Segment 4b.  This portion of the stream is a transition between cold and warm water.  Based on the existing Basic Standards, the Commission adopted a temporary modification of 26.3°C and an underlying standard of 20°C, which raises uncertainty as to the appropriate underlying standard that should be applied to protect the aquatic life community. 
A temporary modification has been adopted to provide time to address this uncertainty and recommend appropriate standards for these water bodies.  During the effective period of this temporary modification, Tri-State, in coordination and collaboration with the Division and CDOW, will conduct cost-effective studies designed to address whether Tri-State's discharge has an adverse impact on the aquatic community. 
The numeric value of this temporary modification was calculated using a mass-balance approach with the following assumptions:  The upstream low-flow was estimated as the 7E3 generated from the amount of water measured at the Brooks Bridge minus the Tri-State cooling water withdrawal.  The upstream temperature was an adjusted MWAT of 24°C which corresponds to the modeled MWAT of the San Miguel at the point of discharge. The discharge characteristics were the Power Station design flow and an effluent temperature of 30°C max. 
It is the Commission's intent to preserve the status quo for Tri-State's discharge for the duration of the temporary modification.  In a stipulation between Tri-State and the Division, Tri-State committed that it will not alter operations on a year round basis in a manner that would adversely affect effluent temperature for the duration of the temporary modification.  The Division agreed that it will maintain the existing daily maximum permit limit of 30°C at the compliance point on a year round basis. 
O. 	Other Changes
The Commission corrected several typographical and spelling errors, and clarified segment descriptions. 
The reference to “Water+Fish Organics” was corrected to “Water+Fish Standards” to incorporate the appropriate standards from both the organics table and the metal parameter table in Regulation No. 31. 
The Water and Fish Organics qualifier on the Uncompahgre River Basin segment 9 was corrected to Fish Ingestion since the segment does not have a Water Supply use. 
The segment description for Upper Gunnison River Basin segment 2 was changed to reflect the incorporation of the Oh-Be-Joyful Wilderness Area into the Raggeds Wilderness Area. 
The segment description for Upper Gunnison River Basin segment 4 was changed to include the Taylor Park Reservoir. 
The segment description for Upper Gunnison River Basin segment 26 was changed to include the Silver Jack Reservoir. 
The segment description for San Miguel River Basin segment 2 was changed to include the Trout Lake. 
PARTIES TO THE RULEMAKING HEARING 
1. San Juan Citizens Alliance 
2. Tri-State Generation and Transmission Association 
3. National Park Service 
4. Mountain Coal Company 
5. West Elk Mine 
6. Homestake Mining Company of California 
7. Umetco Minerals Corporation 
8. Lee Mobile Home Park 
9. The Southwest Mesa County Rural Services Public Improvement District 
10. Animas River Stakeholders Group 
11. Board of County Commissioners of the County of Gunnison, Colorado 
12. The Town of Silverton 
13. The Town of Cedaredge 
14. The Town of Olathe 
15. High Country Citizens Alliance 
16. Upper Gunnison River Water Conservancy District 
17. Colorado Trout Unlimited 18. The City of Grand Junction 
19. Gunnison County Stockgrowers Association, Inc. 
20. The Southwestern Water Conservation District 
21. Vista Verde Village LLC 
22. The Colorado Division of Wildlife 
23. Nucla Sanitation District 
24. Town of Naturita 
25. The Pagosa Area Water and Sanitation District 
26. The Boxelder Sanitation District 
27. City of Ouray 
28. Norwood Sanitation District 
29. U.S. Environmental Protection Agency 
30. Colorado River Water Conservation District 
  35.30	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing; Final Action February 12, 2007; Revisions effective July 1, 2007
The provisions of section 25-8-202(1)(b), 25-8-204; 25-8-402, C.R.S., provide the specific statutory authority for adoption.  The Commission also adopted, in compliance with section 24-4-103(4) C.R.S., the following statement of basis and purpose.  
BASIS AND PURPOSE:
The Commission revised the basin-wide temperature standards as part of the 2007 rulemaking hearing.  These changes clarify the numeric temperature standards that will be in effect until the basin-wide rulemaking hearing in June of 2011.  At that time, the Commission intends to consider segment specific temperature standards for all segments with aquatic life uses. 
The Commission applied 17 ºC as an interim chronic standard for small, high elevation streams that are likely to be habitat for brook trout and cutthroat trout.  First, second and third order streams are defined at  section 31.5 in the Basic Standards.
The Commission also applied 18.2 ºC as an interim chronic standard to waters designated by the Colorado Wildlife Commission as “Gold Medal Fisheries”.  The Commission agrees that it is important to protect these fisheries that provide important recreational and tourism opportunities in the headwaters of Colorado.  This standard is based on a criterion to protect rainbow trout.  The Colorado Division of Wildlife presented evidence that rainbow trout thrive in Gold Medal fisheries because they are provided the necessary forage base and thermal conditions to maximize their consumption and growth.  Because these thermal conditions also represent the upper temperature tolerance range for this species, it was determined that an interim standard of 20°C would not be adequate to protect these fisheries.
For the remainder of the cold water segments, the Commission left the current 20 ºC in place as an interim standard with the clarification that it is a chronic standard.  The existing 30 ºC criterion for warm water segments was left in place as an interim standard with the clarification that is also to be applied as a chronic standard.
PARTIES TO THE RULEMAKING HEARING
1.	The Temperature Group (City of Aurora, City of Boulder, Colorado Springs Utilities, Littleton/Englewood Wastewater Treatment, The Metro Wastewater Reclamation District, Colorado Mining Association, Colorado Rock Products Association, Tri-State Generation & Transmission Assn., Xcel Energy, Denver Water, Northern Colorado Water Conservancy District, Southeastern Colorado Water Conservancy District)
2.	City of Grand Junction
3.	City of Loveland
4.	City of Pueblo
5.	Metro Wastewater Reclamation District
6.	City of Aurora
7.	City of Boulder
8.	Colorado River Water Conservation District 
9.	Colorado Wastewater Utility Council
10.	Bear Creek Watershed Association
11.	Chatfield Watershed Authority
12.	Mountain Coal Company, L.L.C.
13.	Northern Colorado Water Conservancy District
14.	Colorado Rock Products Association
15.	Littleton/Englewood Wastewater Treatment Plant
16.	Northwest Colorado Council of Governments 
17.	Southeastern Colorado Water Conservancy District
18.	Colorado Mining Association 
19.	Colorado Division of Wildlife
20.	South Platte Coalition for Urban River Evaluation 
21.	City and County of Denver 
22.	City of Colorado Springs and Colorado Springs Utilities
23.	City of Westminster
24.	Board of Water Works of Pueblo
25.	Coors Brewing Company
26.	City and County of Broomfield
27.	Centennial Water and Sanitation District
28.	Plum Creek Wastewater Authority
29.	Climax Molybdenum Company
30.	Cripple Creek & Victor Gold Mining Company
31.	Tri-State Generation and Transmission Association
32.	Xcel Energy
33.	Sky Ranch Metropolitan District No. 2
34.	Parker Water and Sanitation District
35.	CAM-Colorado and CAM Mining LLC
36.	Aggregate Industries – WCR, Inc.
37.	Grand County Water and Sanitation District #1, Winter Park Water and Sanitation District, Winter Park West Water and Sanitation District and Fraser Sanitation District
38.	Trout Unlimited and Colorado Trout Unlimited
39.	Colorado Contractors Association
40.	United States Environmental Protection Agency, Region 8
41.	Hot Springs Lodge and Pool
42.	Denver Regional Council of Governments