EXHIBIT 1
WATER QUALITY CONTROL DIVISION
PROPOSAL REGARDING REGULATION #31

31.5	DEFINITIONS
. . .
 (7)	“CHRONIC STANDARD” means the level not to be exceeded by the concentration for either a single representative sample or calculated as an average of all samples collected during a thirty-day period, except for temperature, which shall be based on the WAT (see WAT definition).  As used in tables II and III, chronic represents the level that protects 90 to 95 percent of the genera from chronic toxic effects from unionized ammonia and 95 percent of the genera from chronic toxic effects from metals.  Chronic toxic effects include, but are not limited to, demonstrable abnormalities and adverse effects on survival, growth, or reproduction.  The chronic standard is implemented in combination with a selected duration and frequency of recurrence (section 31.9(1)).
(8)	“COLD WATER BIOTA” means aquatic life, including trout, normally found in waters where the summer weekly average temperature does not often exceed 2017.0 °C.
. . .
(13)	“Daily Maximum Temperature (DM)”  means the highest instantaneous water temperature recorded during a given 24-hour period.
 (13)(14)“DISSOLVED METALS” means that portion of a water and suspended sediment sample which passed through a 0.40 or 0.45 um (Micron) membrane filter.  Determinations of “Dissolved” constituents are made using the filtrate.  This may include some very small (Colloidal) suspended particles which passed through the membrane filter as well as the amount of substance present in true chemical solution.
(14)(15)	“DIVISION” means the Division of Administration of the Colorado Department of Public Health and Environment of which the Water Quality Control Division is a part.
(15)(16)	“E.coli” means Escherichia coli.
(16)(17)	“EFFLUENT-DEPENDENT STREAM” means a stream that would be ephemeral without the presence of wastewater effluent, but has continuous or periodic flows for all or a portion of its reach as the result of the discharge of treated wastewater.
(17)(18)	“EFFLUENT-DOMINATED STREAM” means a stream that would be intermittent or perennial without the presence of wastewater effluent whose flow for the majority of the time is primarily attributable to the discharge of treated water (i.e. greater than 50 percent of the flow consists of treated wastewater for at least 183 days annually, for eight out of the last ten years).
(18)(19)	“EPHEMERAL STREAM” means a stream channel or reach of a stream channel that carries flow during, and for a short duration as the result of, precipitation events or snowmelt.  The channel bottom is always above the groundwater table.
(19)(20)	"Existing quality" means the 85th percentile of the data for ammonia, nitrate, and the dissolved metals, the 50th percentile for total recoverable metals, the 15th percentile of such data for dissolved oxygen, the geometric mean of such data for E. coli, and the range between the 15th and 85th percentiles for pH.  For temperature, for the purposes of implementing the chronic standard, the “existing quality” means the weekly average temperature. 
(20)(21)	“FEDERAL ACT” means the Clean Water Act, U.S.C. Section 1251 et seq., as amended.
(21)(22)	“FLOODPLAIN” means any flat or nearly flat lowland that borders a stream, a lake, or an on-channel reservoir and that may be covered by its waters at flood or high stage as described by the parameter of the probable maximum flood or probable maximum high stage.
(22)(23)	“LC-50” means the concentration of a parameter that is lethal to 50% of the test organisms within a defined time period.
(24)	“Maximum Weekly Average Temperature (MWAT)” means an implementation statistic that is calculated from field monitoring data.  The MWAT is calculated as the largest mathematical mean of multiple, equally spaced, daily temperatures over a seven-day consecutive period, with a minimum of three data points spaced equally through the day.
(23)(25)	“MIXING ZONE” means that area of a water body designated on a case-by-case basis by the Division which is contiguous to a point source and in which certain standards may not apply.
(24)(26)	“NUMERIC VALUE” means the measured concentration of a parameter.
(25)(27)	“PARAMETER” means the chemical constituents or other characteristics of the water such as algae, E. coli, total dissolved solids, dissolved oxygen, or the magnitude of radioactivity levels, temperature, pH, and turbidity, or other relevant characteristics.
(26)(28)	“PERMIT” means a National Pollutant Discharge Elimination System (NPDES) permit, a Colorado Discharge Permit System (CDPS) permit, or other state water quality permit.
(27)(29)	“POTENTIALLY DISSOLVED METALS” means that portion of a constituent measured from the filtrate of a water and suspended sediment sample that was first treated with nitric acid to a pH of less than 2.0 and let stand for 8 to 96 hours prior to sample filtration using a 0.4 or 0.45 m membrane filter.  Note the “Potentially Dissolved” method cannot be used where nitric acid will interfere with the analytical procedure used for the constituent measured.
(28)(30)	“PRIMARY CONTACT RECREATION” means recreational activities where the ingestion of small quantities of water is likely to occur.  Such activities include but are not limited to swimming, rafting, kayaking, tubing, windsurfing, water-skiing, and frequent water play by children.
(29)(31)	“REGIONAL WASTEWATER MANAGEMENT PLAN” means a water quality planning document prepared pursuant to section 208 of the federal Act, sometimes referred to as “208 Plans” or “Water Quality Management Plans.”
(32)	“Reproductive Season” means the portion of the year when a fish species has thermal requirements for successful migration, spawning, egg incubation, fry rearing or other reproductive functions.
(30)(33)	“SALINITY” means total dissolved solids (TDS).
(31)(34)	“STANDARD” means a narrative and/or numeric restriction established by the Commission applied to state surface waters to protect one or more beneficial uses of such waters.  Whenever only numeric or only narrative standards are intended, the wording shall specifically designate which is intended.
(32)(35)	“STATE WATERS” means any and all surface and subsurface waters which are contained in or flow in or through this state, but does not include waters in sewage systems, waters in treatment works of disposal systems, waters in potable water distribution systems, and all water withdrawn for use until use and treatment have been completed.
(33)(36)	“TABLES” means tables I, II, and III, appended to this regulation, which set forth accepted levels for various parameters which will generally protect the beneficial uses of state surface waters.
(34)(37)	“TOTAL RECOVERABLE METALS” means that portion of a water and suspended sediment sample measured by the total recoverable analytical procedure described in “Methods for Chemical Analysis of Water and Wastes,” U.S. Environmental Protection Agency, March, 1979, or its equivalent.
(35)(38)	“TRIBUTARY WETLANDS” means wetlands that are the head waters of surface waters or wetlands within the floodplain that are hydrologically connected to surface waters via either surface or ground water flows.  The hydrologic connection may be intermittent or seasonal, but must be of sufficient extent and duration to normally reoccur annually.  Tributary wetlands do not include constructed or created wetlands.
(36)(39)	“USE ATTAINABILITY ANALYSIS” means an assessment of the factors affecting the attainment of aquatic life uses or other beneficial uses, which may include physical, chemical, biological, and economic factors.
(37)(40)	“USES” see Beneficial Uses.
(38)(41)	“WARM WATER BIOTA” means aquatic life normally found in waters where the summer weekly average temperature frequently exceeds 20 17.0°C.
(39)(42)	“WATER QUALITY-BASED DESIGNATION” means a designation adopted by the Commission for specific state surface waters pursuant to section 31.8(2), to identify which level of water quality protection such waters will receive under the Antidegradation Rule in section 31.8(1).  Such designations are adopted pursuant to the Commission's authority to classify state waters, as set forth in section 25-8-203, C.R.S., and the procedural requirements for classifying state waters shall be applied in adopting such designations.
(40)(43)	“WATER EFFECT RATIO” means a ratio that is computed as a specific pollutant's acute or chronic toxicity value measured in water from the site covered by a standard, divided by the respective acute or chronic toxicity value in laboratory dilution water, as more specifically defined in 40 C.F.R. subsection 131.36(c) (1993).
(41)(44)	“WATER QUALITY STANDARD” see Standard.
(42)(45)	“WEEKLY AVERAGE TEMPERATURE” (WAT) means a mathematical 7-day average of temperatures representative of diel variability, including multiple, equally spaced temperatures for each day mean of multiple, equally spaced, daily temperatures over a seven-day consecutive period, with a minimum of three data points spaced equally through the day.
(43)(46)	“WETLANDS” means those areas that are inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions.
. . .
31.9	FLOW CONSIDERATIONS
(1)	Low Flow Exceptions
Water quality standards shall apply at all times; provided, that in developing effluent limitations or other requirements for discharge permits, the Division shall normally define critical flow conditions using the following low-flow values: the empirically based 30-day average low flow with an average 1-in-3 year recurrence interval (30E3) for chronic standards, (except for temperature limitations, which use the empirically based 7-day average low flow with an average 1-in-3 year recurrence interval (7E3)), and the empirically based 1-day low flow with an average 1-in-3 year recurrence interval (1E3) for acute standards, or the equivalent statistically-based flow.  The period of record for determining low flows shall be based on a minimum of ten years of flow data, except that, when ten years of data is not available, low flows may be determined, on a case-by-case basis, using a period of record of less than ten years.  If more than ten years of flow data is available, it may be more appropriate to establish low flow conditions based on a longer period of record to more accurately reflect site specific conditions.  For streams with seasonal rapidly rising or falling hydrographs, the Division shall use, if so requested by a discharger, the procedure set forth in subparagraphs (a) through (e) below for calculating 30E3 values for those transitional flow periods of the year.  For certain substances such as ammonia, the low flow exceptions may be based on periodic or seasonal flows as determined on a case-by-case basis by the Division. 
. . .
31.11	BASIC STANDARDS APPLICABLE TO SURFACE WATERS OF THE STATE
. . . 
[Revised 31.11(1)(a) Option 1]
(vii)	alter water temperature to a level that impairs aquatic life.  Water temperature shall maintain a normal pattern of seasonal fluctuations, summertime diurnal fluctuations and spatial diversity, with no abrupt changes, and shall have no modification of temperature of a magnitude, frequency and duration deemed deleterious to the aquatic life including during critical reproductive seasons.  Temperatures that exceed the numerical temperature criteria set forth in Table 1 shall be deemed to be harmful to aquatic life, except where site-specific information demonstrates that alternative numeric criteria are more appropriate for protection of aquatic life.  This narrative standard shall not be interpreted or applied in a manner inconsistent with section 25-8-104, C.R.S.
[Revised 31.11(1)(a) Option 2]
(vii)	alter water temperature to a level that impairs aquatic life.  Water temperature shall maintain a normal pattern of seasonal fluctuations, summertime diurnal fluctuations and spatial diversity, with no abrupt changes, and shall have no modification of temperature of a magnitude, frequency and duration deemed deleterious to the aquatic life including during critical reproductive seasons.  Temperatures that exceed the numerical temperature criteria set forth in Table 1 shall be deemed to be harmful to aquatic life, except where a site-specific recalculation procedure demonstrates that alternative numeric criteria are more appropriate for protection of aquatic life.  This narrative standard shall not be interpreted or applied in a manner inconsistent with section 25-8-104, C.R.S.
. . .
31.14	INTEGRATION INTO DISCHARGE PERMITS
. . .
(14)	(Effective 12/31/2007)  Temperature criteria are set forth in Table 1.  Once these criteria are adopted in individual basins, temperature effluent limits in CDPS permits shall be calculated to ensure that In cases where the Division determines that the thermal properties of a discharge will be evaluated relative to instream temperature, the Division will determine the assimilative capacity of the receiving water using standards at 31.11(1)(a)(vii).  Such an evaluation shall also address the following:
a.	Stream temperature shall maintain a normal pattern of diurnal and seasonal fluctuations and shall not exceed the applicable DM or MWAT;
b.	When a mixing zone applies:
i.	the applicable MWAT shall not be exceeded at the edge of the regulatory chronic mixing zone;
ii.	the applicable DM shall not be exceeded at the edge of the regulatory acute mixing zone; and
c.	The spawning MWAT standard, during periods of spawning of cold water fish, spawning standards shall be applied on a case by case basis defined in the NPDES permit for those dischargers whose effluent would affect fish spawning.  This standard will be met at the edge of the regulatory mixing zone if applicable.  The spawning season is dependant on several variables such as habitat and the species expected to be present in the segment.
d.	The effluent does not cause an abrupt change in stream temperature (rate of change no more than a 1 C change over 1 hour, not to exceed 12 C in 24 hours). 
e.a.	No temperature effluent limit will be applied if a discharge is to an effluent dependent dry stream that only has flowing water in response to precipitation and there is no evidence that the aquatic life use may be negatively affected by the discharge.
b.	Protection of reproductive functions of aquatic life shall be considered in CDPS permits on a site-specific basis.
. . .
(17)	Discharge permit limitations for temperature may be included in discharge permits when the Division determines that the effluent contains thermal energy on a continuous or recurring basis in quantities that could cause the stream standards to be threatened or exceeded.  A temperature limit will generally not be considered necessary if representative data submitted by the permittee demonstrates that the thermal energy will not result in a violation of water quality standards.  The Division may require the discharger to provide monitoring data to determine the need for an effluent temperature limit.
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31.16	TABLES
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TABLE I PHYSICAL AND BIOLOGICAL PARAMETERS	
Parameter	Recreational	Aquatic Life	Agriculture	Domestic Water Supply	
 	CLASS E (Existing Primary Contact)
and CLASS U (Undetermined Use)	CLASS P (Potential Primary Contact Use)	CLASS N 
(Not Primary Contact Use)	CLASS 1 COLD WATER BIOTA
	CLASS 1 WARM WATER BIOTA
	CLASS 2
	 	 	
PHYSICAL	 	 	 	 	 	 	 	 	
D.O. (mg/l)(1)(9)	3.0(A)	3.0(A)	3.0(A)	6.0(2)(G) 7.0(spawning)	6.0(2)(G) 7.0(spawning)	5.0(A)	3.0(A)	3.0(A)	
pH (Std. Units)(3)	6.5–9.0 (Bm)	6.5–9.0 (Bm)	6.5–9.0 (Bm)	6.5–9.0(A)	6.5–9.0(A)	6.5–9.0(A)		5.0–9.0(A)	
Suspended Solids(4)									
Temperature (°C)(5)
effective through 12/30/07				Max 20 C, with 3 C
Increase(5)(G)	Max 30 C, with 3 C
Increase(5)(G)				
Temperature (°C)(6)
effective 12/31/07				19.3 ºC (MWAT)a; 
23.8 ºC (DM)b ;
12.6 (spc)(MWAT);

17.8 ºC (ct d) (MWAT)
25.6 ºC (ct) (DM);
16.3 (ct/sp) (MWAT);

24.2 ºC (cwe) (MWAT); 
29.4 ºC (cw)(DM) ;	29.2 ºC (MWAT); 
32.5 ºC (DM)

	Cold:
19.3 ºC (MWAT)a; 
23.8 ºC (DM)b ;
12.6 (spc)(MWAT);

Warm:
29.2 ºC (MWAT); 
32.5 ºC (DM)
			
Temperature (ºC) (5) 
				Rivers & streams = 17.0(ch), 22.4(ac)

Lakes & res = 15.4(ch), 21.7(ac)	Rivers & streams = 25.9(ch), 28.6(ac)

common shiner a  = 
23.0(ch), 28.6(ac)

Lakes & res = 25.2(ch),  27.7(ac)	Same as Class 1			
BIOLOGICAL:									
E. coli per 100 ml	126(7)	205(7)	630(7)					630	
  Note: Capital letters In parentheses refer to references listed in section 31.16(3); Numbers in parentheses refer to Table 1 footnotes.	
Temperature Definitions
a  Common Shiner temperature criteria are to be applied only where common shiner are expected to be present.
a  MWAT =  Maximum weekly average maximum temperature
b  DM = Daily maximum
c sp = Spawning, season is dependent on the species expected to be present in the segment; implemented as a MWAT.
d ct = cutthroat
e cw = cool water	

Table I – Footnotes
. . .
(5)	Effective through 12/30/07:  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.  Generally, a maximum 3 degrees Celsius increase over a minimum of a four‑hour period, lasting for 12 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature.  Where temperature increases cannot be maintained within this range using BMP, BATEA and BPWTT control measures, the Division will determine whether the resulting temperature increases preclude an aquatic life classification.
(6)	Effective 12/31/07:  Instream temperature shall maintain a normal pattern of diurnal and seasonal fluctuations, and spatial diversity, with no abrupt changes and shall have no increase or decrease in temperature of a magnitude, rate and duration deemed deleterious to the resident aquatic life.  
a.	MWAT =  Maximum weekly average temperature;  DM = Daily maximum;  sp = Spawning, during periods of spawning of cold water fish, spawning standards shall be applied on a case by case basis defined in the NPDES permit for those dischargers whose effluent would affect fish spawning.  The spawning standard is applied as an MWAT. 
(5)
a.	The MWAT of a waterbody shall not exceed the chronic temperature criterion more than once in three years, except as described in e, below.
b.	The DM of a waterbody shall not exceed the acute temperature criterion more than once in three years, except as described in e, below.
c.	On a case-by-case basis, the warm-water criteria may be applied to the downstream end of the cold-water segments where the downstream end of the segment adjoins a warm water segment and where there is either free passage for cold-water fish to move upstream or adequate refugia within the segment. 
d.	In order to maintain a normal pattern of summertime diurnal and seasonal temperature fluctuation, any water temperature rise above or fall below the expected ambient temperature regime shall not exceed 3.0 C.
b.e.	The following shall not be considered an exceedance of the criteria:
i.	Air temperature excursion:  ambient water temperature may exceed the criteria in Table 1 or the applicable site-specific standard when the daily maximum air temperature exceeds the 90th percentile value of the annual maximum air temperatures calculated using at least 10 years of air temperature data.
ii.	Low-flow excursion:  ambient water temperature may exceed the criteria in Table 1 or the applicable site-specific standard when the daily stream flow falls below the acute critical low flow or monthly average stream flow falls below the chronic critical low flow, calculated pursuant to Regulation 31.9(1).
iii	Lakes and reservoirs:  When a lakes or reservoir is stratified, the surface layer may exceed the Table I value as long as an adequate refuium is present for aquatic life.  A refugium is water below the mixed layer where DO and temperature standards are met concurrently. the lower levels meet the temperature and dissolved oxygen standards. 
iv.	Natural hot springs:  ambient water temperature in a water body may exceed the criteria in Table 1 or the applicable site-specific standard, when the temperature in that water body is influenced by a natural hot springs.
c.	Where the natural or irreversible human-induced conditions of a waterbody do not meet the numerical table value criteria for temperature, the Commission may apply a site-specific narrative temperature standards to reflect those natural or irreversible human-induced conditions.  Such a site-specific narrative temperature standard would then apply to the segment(s) in question in lieu of numerical standards.  Where appropriate evidence is submitted, the Commission alternatively may adopt site-specific numerical temperature standards.  
(6)	Deleted
. . .
PROPOSED
31.45	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria
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:
In this rulemaking, the Commission adopted new temperature standards for Colorado’s surface waters that rely upon both narrative and numeric criteria.  The revisions to the regulations add definitions, a statewide narrative standard, revised table values and qualifiers, and revised implementation provisions.  The allowable exemptions remain unchanged, except for providing clarification for the lakes exemption.
Overview:  As the Commission indicated in the 2005 Statement of Basis and Purpose, the basis of the original temperature standards had become unclear, the standards had been inconsistently applied in permits and there had been disagreements about how the attainment of these standards should be assessed.  In adopting these revised standards, the Commission has established criteria that are clear and can be consistently and fairly implemented by the Division.  Subsection 31.14(14) was amended and subsection (15) was added to establish general criteria to be followed by the Division in determining when effluent limits related to temperature are necessary in discharge permits.  These criteria are intended to assure that effluent limits are imposed only when thermal discharges can reasonably be expected at a level such that the applicable standards would be threatened or exceeded.  
Temperature standards will also be implemented in the context of determining attainment of standards in individual water bodies, for instance in the context of the biennial compilation of the “List of Impaired Water Still Requiring TMDLs” (the Section 303(d) List).  Methods and process for determining of attainment of the temperature standard will be consistent with the Section 303(d) Listing Methodology as adopted by the Commission for that particular listing cycle.
Water Rights:  Concerns have been raised regarding the potential impact of the proposed temperature standards on the exercise of water rights.  The Commission included a reference to section 25-8-104, C.R.S. in the narrative standard.  Section 25-8-104 states in part that “Nothing in this article [the Colorado Water Quality Control Act] shall be construed, enforced or applied so as to cause or result in material injury to water rights.”  
In cases where it is determined that the classified aquatic life use is adversely impacted by any pollutant, the Commission believes that it is appropriate to place the impacted segment on the Section 303(d) list.  When a segment is placed on the 303(d) for any reason, the Division (along with any interested parties) then investigates the source of the impairment.  If the cause of non-attainment is deemed to be natural or irreversible man-induced, then a site-specific standard is appropriate.  See Regulation 31.7(1)(b)(ii), 5 CCR 100-31, section 31.7(1)(b)(ii).  In cases where a temperature standard exceedance is determined to be caused by the valid exercise of water rights and the exceedance cannot be eliminated without adversely impacting the exercise of water rights, consistent with state law and policy, the Commission would consider that to be an irreversible anthropogenic condition, and thus would support adoption of a site-specific standard.  
Similarly, Colorado’s 401 certification regulation (Regulation No. 82.5(6)) provides that 401 Certification shall not be denied where the imposition of conditions or denial would result in material injury to water rights as prohibited under section 25-8-104, C.R.S.  In such case, the Division, the project proponents and any commenters are to examine and implement, where appropriate, any means to prevent, reduce or mitigate water quality impacts identified during the permitting process and associated with the exercise of water rights.  Where such measures are found they may be included in the Division’s certification determination.  This process would apply to temperature standards in the same manner as other water quality standards.
Definitions:  Definitions were added to section 31.5 for terms used in the context of revised temperature standards.  Pre-existing definitions were renumbered.
[Narrative Standards language Option 1]
Narrative Standard:  A narrative standard has been added to section 31.11 of the Basic Standards to address human-caused alterations that may be detrimental to aquatic life.  This narrative includes a general prohibition of temperature alterations that impair aquatic life, as well as a narrative description of temperature conditions to be maintained to assure aquatic life protection.  The numerical table value criteria also adopted in this rulemaking will be used as the starting point for implementation of the narrative standard where an implementation issue arises (e.g., for discharge permits or section 303(d) listing issues).  Specifically, the table value criteria will be used as the default numerical values for implementation of the narrative standard, although the Division will not be bound by these table values in applying the narrative standard in a site-specific circumstance.  The Division or other interested persons may bring forth information regarding site-specific circumstances that may warrant variation from the table value criteria in implementing the narrative standard in a specific instance, including implementation of the narrative standard for the purpose of section 303(d) listing.  The Commission anticipates that where a narrative temperature standard implementation issue arises and the Division or others believe that numerical criteria other than the Table I default values are most appropriate for protection of the classified aquatic life use, adoption of site-specific numerical temperature criteria will be considered in the next water quality standards review for that basin.
The Commission intends that implementation guidance will be developed by the Division to facilitate implementation of the narrative standard.  However, the Commission does not intend that implementation of the narrative standard will be delayed pending finalization of such guidance. 
[Narrative Standards language Option 2, double underline/strike out indicates changes from Option 1]
Narrative Standard:  A narrative standard has been added to section 31.11 of the Basic Standards to address human-caused alterations that may be detrimental to aquatic life.  This narrative includes a general prohibition of temperature alterations that impair aquatic life, as well as a narrative description of temperature conditions to be maintained to assure aquatic life protection.  The numerical table value criteria also adopted in this rulemaking will be used as the starting point for implementation of the narrative standard where an implementation issue arises (e.g., for discharge permits or section 303(d) listing issues).  Specifically, the table value criteria will be used as the default numerical values for implementation of the narrative standard,.  although the Division will not be bound by these table values in applying the narrative standard in a site-specific circumstance.  THowever, the Division or other interested persons may bring forth information regarding conduct a site-specific circumstances recalculation procedure in accordance with Commission Policy 2006-1, to develop alternative criteria to protect species that are expected to occur at the site., based upon that may warrant variation from the table value criteria in implementing the narrative standard in a specific instance, including This alternative approach to implementation of the narrative standard may be used for the purpose of section 303(d) listing or permitting.  The Commission anticipates that where a narrative temperature standard implementation issue arises and the Division or others believe that site-specific recalculated numerical criteria other than the Table I default values are most appropriate for protection of the classified aquatic life use, adoption of site-specific numerical temperature criteria will be considered in the next water quality standards review for that basin.  Where natural or irreversible human-caused conditions of a water body indicate that the values in Table 1 are not appropriate for protection of the aquatic life use, the Commission may adopt site-specific ambient standards (as discussed at 31.7(1)(b)(ii)).  In addition, where appropriate evidence, such as a use attainability analysis, is submitted the Commission may adopt site-specific numerical temperature standards (as discussed at 31.7.(1)(b)(iii).
The Commission intends that implementation guidance will be developed by the Division to facilitate implementation of the narrative standard.  However, the Commission does not intend that implementation of the narrative standard will be delayed pending finalization of such guidance. 
New Temperature Table Values:  One result of the 2005 Basic Standards hearing was a focused effort on developing a sound methodology, re-reviewing the laboratory-based temperature effect literature, and developing a new, more robust temperature database.  
The methodology for developing temperature criteria was the subject of an administrative action hearing in April, 2006, that resulted in adoption of WQCC Policy 2006-1: Temperature Criteria Methodology.  The policy is intended as a general informational guide of the Commission’s approach to the adoption of these criteria and standards.  As stated in the Policy, it is not intended and should not be interpreted to limit any options that may be considered, or adopted by the Commission in future rulemaking proceedings.
The new table values, adopted in this hearing, were developed using the laboratory-based studies of individual fish species’ tolerance to elevated water temperatures.  For each aquatic community the tolerances were ranked and the 95th percentile was selected as the operative criterion, except in the case of cold-water aquatic life.  
Cold water numeric criteria:  The cold water criteria were generated using laboratory generated thermal tolerance information for the following cold water species:  brook trout, brown trout, cutthroat trout, lake trout, rainbow trout and sockeye salmon.  Adequate information is lacking for other Colorado cold water species.  The fish species were grouped into two communities “Rivers and Streams” (all the species except lake trout and sockeye salmon) and “Lakes and Reservoirs” (all the species).  Other groupings, including east and west slope were investigated, however provided no significant difference in criteria.  For “Rivers and Streams” the Policy 2006-1 methods, 95th percentile did not protect brook trout (the most sensitive species).  Since brook trout are an ecologically important species in cold-water communities, and they are more sensitive than that of the 95th percentile species, the cold criteria were lowered to ensure protection of brook trout.  Cutthroat trout are protected by the cold water rivers and streams criteria, and therefore the Cutthroat subclass was removed.  The Commission anticipates that as the Division and interested parties continue to collect thermal tolerance studies, the database will become more robust and these decisions will be revisited.
Warm water numeric criteria:  The warm water numeric criteria were developed using laboratory-based temperature studies of fish species.  As with development of the cold criteria, several community groupings were evaluated.  With the current data, it was determined that criteria for the three sub-classes would be promulgated.  The  “Rivers and Streams” criteria are based on information about the Arkansas darter, Arkansas River shiner, black bullhead, boneytail, brook stickleback, brown bullhead, central stoneroller, channel catfish, creek chub, fathead minnow, finscale dace, golden shiner, green sunfish, hornyhead chub, Johnny darter, longnose dace, northern redbelly dace, orangethroat darter, plains killifish, plains minnow, pumpkinseed, quillback, red shiner, roundtail chub, sand shiner, smallmouth bass, southern redbelly dace, speckled dace, spottail shiner, western mosquitofish, white sucker, and yellow bullhead.  The “Lakes and Reservoir” criteria are based on information about the black crappie, bluegill, gizzard shad, largemouth bass, northern pike, sauger, striped bass, striped bass x white bass, walleye, white bass, white crappie, and yellow perch.  Adequate information is lacking for other Colorado warm water species. 
The Commission acknowledges that all of these fish species do not occur in all warm water locations.  For instance, the white bass only occurs in east slope reservoirs, and channel catfish generally occur warm water lakes reservoirs, ponds, and in moderate to large rivers.  Neither of these may be appropriate in some locations on the western slope.  However, rather than include all the combinations in Table 1, the Commission adopted table values for only three subclasses.  The newly revised narrative standard allows for refinement of criteria on a site-specific basis using the recalculation procedures in Policy 2006-1 without the burden of a Commission hearing.  This provides the Division and interested parties the flexibility to develop site-specific solutions based on the species expected to be present.
The third sub-class has been created to protect the common shiner.  This fish species occupies a relatively small portion of Colorado’s waters, specifically the eastern slope transition zone.  Existing data for the common shiner indicates that it is sensitive to chronic high temperatures, relative to other warm water fish.  (The acute criterion is based on the information from the entire warm water rivers and streams grouping.) If this species in included with the other warm water rivers and stream species, following Policy 2006-1, the resulting criteria are over protective for waters with no common shiner.  Since the range of the common shiner is relatively well defined, the Commission decided that it was more appropriate to create a separate subclass rather than have interested parties outside the common shiner’s range have to go through the recalculation procedure.  The Commission directs the Division to rely upon information from the Colorado Division of Wildlife for determining where common shiners are expected to be present.
Spawning/Reproductive Seasons:  The Commission revised the provisions to protect spawning in order to broaden the consideration to all the reproductive functions.  Reproductive seasons are specifically identified as needing protection in the narrative standard at 31.11.  The proposed consideration of reproductive season standard is to meet the site-specific thermal requirements for successful migration, spawning, egg incubation, fry rearing and other reproductive functions.  These particular life stages and behaviors warrant more protective criteria than required for the young adult and adult life stages, however, there are many site-specific considerations.  A single table value for each use subcategory would not address the site-specific factors.  The operative numeric criterion will be dependent on the species expected to be present in the segment in a given season, and is applied as a chronic temperature criterion.  Guidance will be developed to aid the Division and the public in how to implement the narrative protection of reproductive seasons.
Normal Pattern of Seasonal Fluctuation:  The narrative standard contains the requirement that temperature shall maintain a normal pattern of seasonal fluctuation.  This component is intended to preserve thermal cues necessary for protection of aquatic life cycles.  The Commission directs the Division to establish index patterns of normal of seasonal fluctuation for sites that represent the variety of Colorado’s waters in guidance.  Index patterns should take into account year-to-year variability.  The Commission recognizes that the point of application of the standards may be a significant distance from the index site.  In those cases, the Commission encourages entities to collect data that could be used to develop an additional index site for use at that location.  It is the Commission’s intent that when the Division or interested parties evaluate whether a specific water body is meeting the normal seasonal fluctuation requirement, the pattern should be within 3 °C of the index pattern.
Normal Pattern of Summertime Diurnal Fluctuation: The narrative standard contains the requirement that temperature shall maintain a normal pattern of summertime diurnal fluctuation.  The addition of “summertime” represents a modification of the longstanding language in the Basic Standards.  While it is clear that aquatic life need night-time cooling during the summers to allow recovery from daily afternoon high temperatures, it is not clear that this recovery is necessary in the rest of the year.  The Division’s index patterns discussed above shall include summertime diurnal fluctuation information.  It is the Commission’s intent that when the Division or interested parties evaluate whether a specific water body is meeting the normal seasonal fluctuation requirement, the pattern should be within 3 °C of the index pattern.  
Normal Patten of Spatial Diversity:  The narrative standard also contains the requirement that temperature shall maintain a normal pattern of spatial diversity.  Spatial diversity is a concept that incorporates the importance of a distribution of conditions along the stream reach.  Natural aquatic ecosystems have a range of temperatures available to organisms in microhabitats.  This array of microhabitats makes it possible for a broader range of organisms and life-cycles to flourish in the aquatic system.  Although spatial diversity is critical to a fully functioning aquatic community, the Commission does not see a way to quantify or define the lower threshold in regulation at this time.  The Commission’s intent is that the Division use its discretion to implement the narrative requirement for spatial diversity is situations where there is significant evidence that an activity will or does create spatial uniformity that will threaten or impair the aquatic life use.
Abrupt Changes / Thermal Shock:  The thermal shock provisions were reviewed and revised.  The provision 31.14 (14)(d) was eliminated and replaced by an additional subsection of footnote 5 that restricts the acceptable human-caused temperature change to 3 °C above or below the expected ambient temperature regime.  The Commission acknowledges the debate about oversimplification of a complex physiological phenomenon, however there is a need to provide clear direction for implementation of the narrative prohibition of abrupt changes.  Scientific literature suggest that deviation from natural ambient water temperatures should be limited to 3 °C or less to prevent adverse impacts to resident fish populations.  
Transition Zones: In 2005, the Commission adopted the cool water (“cw”) qualifier to acknowledge that temperature regimes are a continuum and the transition between cold and warm is not abrupt.  The Commission endorses the concept of the recognizing the transition zone, but decided that rather than having separate criteria for the transition zone, it is more appropriate to wait for the results of the Aquatic Life work group’s effort to propose refined aquatic life uses.  To help assure a reasonable approach in the interim, the Commission added a new condition to Table 1 footnote 5.  This provision allows on a case-by-case basis, the warm-water criteria to be applied to the downstream end of the cold-water segments where the downstream end of the segment adjoins a warm water segment and where there is either free passage for cold-water fish to move upstream or adequate refugia within the segment.
In addition, the Commission has also accounted for transition zone differences by providing for more protective standards for the upper end of warm water segments for the common shiner is present.
[Permit Implementation language Option 1]
Implementation in Discharge Permits:  The provisions in 31.14(14) addressing how temperature standards are to be implemented in discharge permits were reviewed and revised.  Subsection 31.14(15) was added to record the Commission’s intention regarding how the division should approach determining when temperature limits should be added to permits.
The narrative criteria that require protection of reproductive functions shall be applied on a seasonal basis.  When the Division determines that there is habitat suitable for reproduction by fish species that are expected to be present and that habitat may be affected by the discharge, the need for permit conditions shall be determined, taking into account the mixing zone provisions at 31.10.
The Commission added language at 31.14(15) to emphasize that the Division will only impose temperature effluent limits in permits when the thermal energy in the discharge presents a significant threat to the attainment of standards.
When implementing the narrative standard in discharge permits the Division looks first to site-specific temperature standards.  If no site-specific standards have been adopted, the Division will use the table value criteria as the default numerical values.  However, the Division or other interested persons may bring forth information regarding site-specific circumstances that may warrant variation from the table value criteria in implementing the narrative standard in a specific instance.
[Permit Implementation language Option 2, double underline/strike out indicates changes from Option 1]
Implementation in Discharge Permits:  The provisions in 31.14(14) addressing how temperature standards are to be implemented in discharge permits were reviewed and revised.  Subsection 31.14(15) was added to record the Commission’s intention regarding how the division should approach determining when temperature limits should be added to permits.
The narrative criteria that required protection of reproductive functions shall be applied on a seasonal basis.  When the Division determines that there is habitat suitable for reproduction by fish species that are expected to be present and that habitat may be affected by the discharge, the need for permit conditions shall be determined, taking into account the mixing zone provisions at 31.10.
The Commission added language at 31.14(15) to emphasize that the Division will only impose temperature effluent limits in permits when the thermal energy in the discharge presents a significant threat to the standards.
When implementing the narrative standard in discharge permits the Division looks first to site-specific temperature standards.  If no site-specific standards have been adopted, the Division will use the table value criteria as the default numerical values.  However, the Division or other interested persons may bring forth results of information regarding site-specific recalculation procedure circumstances that supports a may warrant variation from the table value criteria in implementing the narrative standard in a specific instance.

EXHIBIT 2
WATER QUALITY CONTROL DIVISION
PROPOSAL REGARDING REGULATION #32

32.5	BASIC STANDARDS
(1)	TEMPERATURE
	All waters of the Arkansas River Basin are subject to the narrative temperature standard set forth at section 31.11(1)(vii).  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.  Generally, a maximum 3 C increase over a minimum of a four-hour period, lasting 13 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature.  Where temperature increases cannot be maintained within this range using Best Management Practices (BMP), Best Available Technology Economically Achievable (BATEA), and Best Practical Waste Treatment Technology (BPWTT) control measures, the Commission may determine by a rulemaking hearing in accordance with the requirements of the applicable statutes and the basic regulations, whether or not a change in classification is warranted.

PROPOSED

32.34	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria
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 modified the reference to temperature standards at 32.5(1) to conform with changes made concurrently to the Basic Standards (Regulation No 31) at 31.11 and 31.16 Table 1.

EXHIBIT 3
WATER QUALITY CONTROL DIVISION
PROPOSAL REGARDING REGULATION #33

33.5	BASIC STANDARDS
(1)	All waters of Region12 are subject to the narrative temperature standard set forth at section 31.11(1)(vii).  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.  Generally, a maximum 3 C increase over a minimum of a four-hour period, lasting 13 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature.  Where temperature increases cannot be maintained within this range using Best Management Practices (BMP), Best Available Technology Economically Achievable (BATEA), and Best Practical Waste Treatment Technology (BPWTT) control measures, the Commission may determine by a rulemaking hearing in accordance with the requirements of the applicable statutes and the basic regulations, whether or not a change in classification is warranted.

PROPOSED

33.35	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria
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 modified the reference to temperature standards at 33.5(1) to conform with changes made concurrently to the Basic Standards (Regulation No 31) at 31.11 and 31.16 Table 1.

EXHIBIT 4
WATER QUALITY CONTROL DIVISION
PROPOSAL REGARDING REGULATION #34

34.5	BASIC STANDARDS
(1)	TEMPERATURE
	All waters of the San Juan/Dolores River Basin are subject to the narrative temperature standard set forth at section 31.11(1)(vii).  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.  Generally, a maximum 3 C increase over a minimum of a four-hour period, lasting 12 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature.  Where temperature increases cannot be maintained within this range using Best Management Practices (BMP), Best Available Technology Economically Achievable (BATEA), and Best Practical Waste Treatment Technology (BPWTT) control measures, the Commission may determine by a rulemaking hearing in accordance with the requirements of the applicable statutes and the basic regulations, whether or not a change in classification is warranted.

PROPOSED

34.31	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria
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 modified the reference to temperature standards at 34.5(1) to conform with changes made concurrently to the Basic Standards (Regulation No 31) at 31.11 and 31.16 Table 1.

EXHIBIT 5
WATER QUALITY CONTROL DIVISION
PROPOSAL REGARDING REGULATION #35

35.5	BASIC STANDARDS
(1)	TEMPERATURE
	All waters of the Gunnison River/Lower Dolores River Basins are subject to the narrative temperature standard set forth at section 31.11(1)(vii).  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.  Generally, a maximum 3 C increase over a minimum of a four-hour period, lasting 12 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature.  Where temperature increases cannot be maintained within this range using Best Management Practices (BMP), Best Available Technology Economically Achievable (BATEA), and Best Practical Waste Treatment Technology (BPWTT) control measures, the Commission may determine by a rulemaking hearing in accordance with the requirements of the applicable statutes and the basic regulations, whether or not a change in classification is warranted.

PROPOSED

35.23	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria
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 modified the reference to temperature standards at 35.5(1) to conform with changes made concurrently to the Basic Standards (Regulation No 31) at 31.11 and 31.16 Table 1.

EXHIBIT 6
WATER QUALITY CONTROL DIVISION
PROPOSAL REGARDING REGULATION #36

36.5	BASIC STANDARDS
(1)	TEMPERATURE
	All waters of the Rio Grande Basin are subject to the narrative temperature standard set forth at section 31.11(1)(vii).  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.  Generally, a maximum 3 C increase over a minimum of a four-hour period, lasting 13 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature.  Where temperature increases cannot be maintained within this range using Best Management Practices (BMP), Best Available Technology Economically Achievable (BATEA), and Best Practical Waste Treatment Technology (BPWTT) control measures, the Commission may determine by a rulemaking hearing in accordance with the requirements of the applicable statutes and the basic regulations, whether or not a change in classification is warranted.

PROPOSED

36.25	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria
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 modified the reference to temperature standards at 36.5(1) to conform with changes made concurrently to the Basic Standards (Regulation No 31) at 31.11 and 31.16 Table 1.

EXHIBIT 7
WATER QUALITY CONTROL DIVISION
PROPOSAL REGARDING REGULATION #37

37.5	BASIC STANDARDS
(1)	TEMPERATURE
	All waters of the Colorado River Basin are subject to the narrative temperature standard set forth at section 31.11(1)(vii).  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.  Generally, a maximum 3 C increase over a minimum of a four-hour period, lasting 12 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature.  Where temperature increases cannot be maintained within this range using Best Management Practices (BMP), Best Available Technology Economically Achievable (BATEA), and Best Practical Waste Treatment Technology (BPWTT) control measures, the Commission may determine by a rulemaking hearing in accordance with the requirements of the applicable statutes and the basic regulations, whether or not a change in classification is warranted.

PROPOSED

37.19	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria
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 modified the reference to temperature standards at 37.5(1) to conform with changes made concurrently to the Basic Standards (Regulation No 31) at 31.11 and 31.16 Table 1.

EXHIBIT 8
WATER QUALITY CONTROL DIVISION
PROPOSAL REGARDING REGULATION #38

38.5	BASIC STANDARDS
(1)	TEMPERATURE
	All waters of the South Platte, Laramie, Republican and Smoky Hill River Basins are subject to the narrative temperature standard set forth at section 31.11(1)(vii).  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.  Generally, a maximum 3 C increase over a minimum of a four-hour period, lasting 12 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature.  Where temperature increases cannot be maintained within this range using Best Management Practices (BMP), Best Available Technology Economically Achievable (BATEA), and Best Practical Waste Treatment Technology (BPWTT) control measures, the Commission may determine by a rulemaking hearing in accordance with the requirements of the applicable statutes and the basic regulations, whether or not a change in classification is warranted.

PROPOSED

38.59	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria
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 modified the reference to temperature standards at 38.5(1) to conform with changes made concurrently to the Basic Standards (Regulation No 31) at 31.11 and 31.16 Table 1.

EXHIBIT 9
THE TEMPERATURE GROUP
PROPOSED CHANGES TO REGULATION #31

31.5 DEFINITIONS
“ACUTE STANDARD” means the level not to be exceeded by the concentration in a single sample or calculated as an average of all samples collected during a one-day period, except for temperature, which shall be based on the daily maximum temperature when a numeric standard applies. As used in tables II and III, acute represents one-half of the 96-hour LC-50 that protects 95 percent of the genera in a water body from lethal effects. The acute standard is implemented in combination with a selected duration and frequency of recurrence (section 31.9(1)). 
“CHRONIC STANDARD” means the level not to be exceeded by the concentration for either a single representative sample or calculated as an average of all samples collected during a thirty-day period, except for temperature, which shall be based on the WAT when a numeric standard applies. As used in tables II and III, chronic represents the level that protects 90 to 95 percent of the genera from chronic toxic effects from unionized ammonia and 95 percent of the genera from chronic toxic effects from metals. Chronic toxic effects include, but are not limited to, demonstrable abnormalities and adverse effects on survival, growth, or reproduction. The chronic standard is implemented in combination with a selected duration and frequency of recurrence (section 31.9(1)). 
“Cold Water Biota” means aquatic life, including trout, normally found in waters where the summer temperature does not often frequently exceed 20 ºC.
“Daily Maximum Temperature (DM)”  means the highest instantaneous water temperature recorded during a given 24-hour period.
“Maximum Weekly Average Temperature (MWAT)” An implementation statistic that is calculated from field monitoring data.  The MWAT is calculated as the largest mathematical mean of multiple, equally spaced, daily temperatures over a seven-day consecutive period, with a minimum of three equally spaced datapoints per day.
“Weekly Average Temperature (WAT)” means the mathematical mean of multiple, equally spaced, daily temperatures over a seven-day consecutive period, with a minimum of three equally spaced data points per day.
31.9	FLOW CONSIDERATIONS
(1) Low Flow Exceptions
Water quality standards shall apply at all times; provided, that in developing effluent limitations or other requirements for discharge permits, the Division shall normally define critical flow conditions using the following low-flow values: the empirically based 30-day average low flow with an average 1-in-3 year recurrence interval (30E3) for chronic standards, except for temperature limitations which use the empirically based 7-day average low flow with an average 1-in-3 year recurrence interval (7E3), and the empirically based 1-day low flow with an average 1-in-3 year recurrence interval (1E3) for acute standards, or the equivalent statistically-based flow. The period of record for determining low flows shall be based on a minimum of ten years of flow data, except that, when ten years of data is not available, low flows may be determined, on a case-by-case basis, using a period of record of less than ten years. If more than ten years of flow data is available, it may be more appropriate to establish low flow conditions based on a longer period of record to more accurately reflect site specific conditions. For streams with seasonal rapidly rising or falling hydrographs, the Division shall use, if so requested by a discharger, the procedure set forth in subparagraphs (a) through (e) below for calculating 30E3 values for those transitional flow periods of the year. For certain substances such as ammonia, the low flow exceptions may be based on periodic or seasonal flows as determined on a case-by-case basis by the Division. 
31.11 BASIC STANDARDS APPLICABLE TO SURFACE WATERS OF THE STATE
. . .
(1) 	Except where authorized by permits, BMPs, 401 certifications, or plans of operation approved by the Division or other applicable agencies, state surface waters shall be free from substances attributable to human-caused point source or nonpoint source discharge in amounts, concentrations or combinations which: 
(a) 	for all surface waters except wetlands; 
(i) 	can settle to form bottom deposits detrimental to the beneficial uses. Depositions are stream bottom buildup of materials which include but are not limited to anaerobic sludges, mine slurry or tailings, silt, or mud; or 
(ii)	form floating debris, scum, or other surface materials sufficient to harm existing beneficial uses; or 
(iii) 	produce color, odor, or other conditions in such a degree as to create a nuisance or harm existing beneficial uses or impart any undesirable taste to significant edible aquatic species or to the water; or 
(iv) 	are harmful to the beneficial uses or toxic to humans, animals, plants, or aquatic life; or 
(v) 	produce a predominance of undesirable aquatic life; or 
(vi) 	cause a film on the surface or produce a deposit on shorelines; or 
(vii) 	alter water temperature to a level that results in an impairment of aquatic life uses, and  
. . .
31.14 INTEGRATION INTO DISCHARGE PERMITS
(14)	(Effective 12/31/2007) Temperature criteria are set forth in Table 1. Once these criteria are adopted in individual basins, temperature effluent limits in CDPS permits shall be calculated to ensure that 
(14)	For purpose of implementing the narrative temperature standard in section 31.11(1)(a)(vii), the Division shall evaluate thermal properties of a discharge relative to instream temperatures. Such an evaluation shall also address the following:
a. 	Stream temperature shall maintain a normal pattern of diurnal and seasonal fluctuations and shall not exceed the applicable DM or MWAT;  
ba.	When a mixing zone applies: 
i.	the applicable MWATchronic standard shall not be exceeded at the edge of the regulatory chronic mixing zone; 
ii.	the applicable DMacute standard shall not be exceeded at the edge of the regulatory acute mixing zone; and 
cb.	The spawning MWAT standard, during periods of spawning of cold water fish, spawning standards shall be applied on a case by case basis defined in the NPDES permit for those dischargers whose effluent would affect fish spawning. This standard will be met at the edge of the regulatory mixing zone if applicable. The spawning season is dependant on several variables such as habitat and the species expected to be present in the segment. During periods of the critical reproductive season(s), protection of the spawning phase shall be considered on a site-specific basis.
d. 	the effluent does not cause an abrupt change in stream temperature (rate of change no more than a 1 °C change over 1 hour, not to exceed 12 °C in 24 hours). 
ec.	No temperature effluent limit will be applied if a discharge is to a dry stream that only has flowing water in response to precipitation and to discharges to effluent dependent or effluent dominated streams as long as there is no evidence that the aquatic life use may be negatively affected by the discharge.

TABLE I PHYSICAL AND BIOLOGICAL PARAMETERS	
Parameter 	Recreational 	Aquatic Life	Agriculture	Domestic Water Supply 	
	CLASS E (Existing Primary Contact) and CLASS U (Undetermined Use) 	CLASS P (Potential Primary Contact Use) 	CLASS N 
(Not Primary Contact Use) 	CLASS 1 COLD WATER BIOTA 	CLASS 1 WARM WATER BIOTA 	CLASS 2			
D.O. (mg/l)(1)(9)	3.0(A)	3.0(A)	3.0(A)	6.0(2)(G) 7.0(spawning) 	6.0(2)(G) 7.0(spawning) 	5.0(A)	3.0(A)	3.0(A)	
pH (Std. Units)(3)	6.5–9.0 (Bm) 	6.5–9.0 (Bm) 	6.5–9.0 (Bm) 	6.5–9.0(A) 	6.5–9.0(A)	6.5–9.0(A)		5.0–9.0(A)	
Suspended Solids(4)									
Temperature (°C)(5) effective through 12/30/07		 		Max 20 °C, 
with 3 °C  Increase(5)(G) 	Max 30 °C, 
with 3 °C Increase(5)(G)		
Temperature (°C)(6) 
effective 12/31/07 	 		; 	19.3 ºC (MWAT)a; 
23.8 ºC (DM)b ; 
12.6 (spc)(MWAT); 17.8 ºC (ct d) (MWAT) 
25.6 ºC (ct) (DM); 
16.3 (ct/sp) (MWAT)24.2 ºC (cwe) (MWAT); 
29.4 ºC (cw)(DM) ; 	29.2 ºC (MWAT); 
32.5 ºC (DM) 	Cold: 
19.3 ºC (MWAT)a; 
23.8 ºC (DM)b ; 
12.6 (spc)(MWAT); 
Warm: 
29.2 ºC (MWAT); 
32.5 ºC (DM) 	
Note: Capital letters In parentheses refer to references listed in section 31.16(3); Numbers in parentheses refer to Table 1 footnotes. 	
Temperature Definitions
a MWAT = Maximum weekly average maximum temperature 
b DM = Daily maximum 
c sp = Spawning, season is dependent on the species expected to be present in the segment; implemented as a MWAT. 	

Table I – Footnotes 
(5)	Effective through 12/30/07: 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. Generally, a maximum 3 degrees Celsius increase over a minimum of a four-hour period, lasting for 12 hours maximum, is deemed acceptable for discharges fluctuating in volume or temperature. Where temperature increases cannot be maintained within this range using BMP, BATEA and BPWTT control measures, the Division will determine whether the resulting temperature increases preclude an aquatic life classification. Temperature will be controlled by Temperature Implementation Guidance, Basic Standards, and Best Management Practices (BMPs). 
(6)	Effective 12/31/07: Instream temperature shall maintain a normal pattern of diurnal and seasonal fluctuations, and spatial diversity, with no abrupt changes and shall have no increase or decrease in temperature of a magnitude, rate and duration deemed deleterious to the resident aquatic life. 
a.	MWAT = Maximum weekly average temperature; DM = Daily maximum; sp = Spawning, during periods of spawning of cold water fish, spawning standards shall be applied on a case by case basis defined in the NPDES permit for those dischargers whose effluent would affect fish spawning. The spawning standard is applied as an MWAT. 
b.	The following shall not be considered an exceedance of the criteria: 
i.	Air temperature excursion: ambient water temperature may exceed the criteria in Table 1 or the applicable site-specific standard when the daily maximum air temperature exceeds the 90th percentile value of the annual maximum air temperatures calculated using at least 10 years of air temperature data. 
ii. 	Low-flow excursion: ambient water temperature may exceed the criteria in Table 1 or the applicable site-specific standard when the daily stream flow falls below the acute critical low flow or monthly average stream flow falls below the chronic critical low flow, calculated pursuant to Regulation 31.9(1). 
iii 	Lakes and reservoirs: When a lakes or reservoir is stratified, the surface layer may exceed the Table I value as long as the lower levels meet the temperature and dissolved oxygen standards. 
iv. 	Natural hot springs: ambient water temperature in a water body may exceed the criteria in Table 1 or the applicable site-specific standard, when the temperature in that water body is influenced by a natural hot springs. 
c. 	Where the natural or irreversible human-induced conditions of a waterbody do not meet the numerical table value criteria for temperature, the Commission may apply a site-specific narrative temperature standards to reflect those natural or irreversible human-induced conditions. Such a site-specific narrative temperature standard would then apply to the segment(s) in question in lieu of numerical standards. Where appropriate evidence is submitted, the Commission alternatively may adopt site-specific numerical temperature standards. 
PROPOSED
31.45	STATEMENT OF BASIS, SPECIFIC STATUTORY AUTHORITY AND PURPOSE:  January 2007 Rulemaking Hearing, Regarding Temperature Criteria 
Temperature Table Values (section 31.16 Table I)
Having considered the evidence submitted in this rulemaking, as well as additional evidence submitted in the April 2006 Administrative Action Hearing, the Commission believes that it is appropriate to move forward toward revised temperature standards. Since this is a very complex issue and it is apparent that natural, site-specific conditions affect temperature for both attainment and permitting, the Commission adopted revised narrative temperature criteria. 
The original Colorado temperature standards were first adopted by the Commission in 1978. Over the years, the basis for the original standards has become unclear, the standards have been inconsistently applied in permits, and there have been disagreements about how the attainment of these standards should be assessed. 
In this rulemaking, the Commission adopted a narrative temperature standard.  The decision to abandon the existing numeric standard approach; e.g., the existing 20 ºC for cold and 30 ºC for warm, or other measures such as Maximum Weekly Average Temperature (“MWAT”) and Daily Maximum (“DM”), is based on the site-specific nature of temperature.  The Commission notes that unlike more conservative elements, such as metals, temperature varies in response to weather, elevation, channel form, aspect (north-south/east-west), flow, and other factors – all of which may differ even within specific regulatory segments.  
The intention of the Commission is to treat temperature similar to other narrative standards, such as suspended solids, with development of a detailed Implementation Guidance Document.  The Commission believes that such an Implementation Guidance Document would include protocols for 1) determining attainment with a narrative temperature standard, 2) methods for developing site-specific temperature standards, 3) methods for determining non-attainment, consistent with 303(d) implementation guidance, 4) methods for determining thermal mixing zones, consistent with Mixing Zone Guidance, 5) and species-specific thermal requirements (chronic and acute), with underlying data and detailed methods used to develop those values.  
The Commission expects the Implementation Guidance Document to include discussions of appropriate methods for determining numeric values, when appropriate, based on implementation statistics such as MWAT (chronic) and DM (acute), to provide protection against sublethal and lethal effects that elevated temperature can cause. The Commission also expects the Implementation Guidance Document would include consideration of the need to protect cold water fish during spawning seasons when they are potentially more sensitive to increased temperature. Due to the complexity of temperature in streams and the potential for natural systems to have temperatures exceeding the narrative and site-specific numeric standards, the Commission expects the Implementation Guidance Document to include a series of allowable excursions. Such excursions in the Implementation Guidance Document may include, but will not restricted to: 
Air temperature excursion: When the daily maximum air temperature exceeds the 90th percentile value of the annual maximum air temperatures calculated using at least 10 years of air temperature data. 
Low-flow excursion: Consistent with Regulation 31.9(1) 
Lakes and reservoirs: Surface layers of a stratified lake or reservoir as long as the lower levels meet the narrative temperature and dissolved oxygen standards. 
Natural hot springs: When the temperature in a water body is influenced by a natural hot springs. 
In adopting new narrative temperature criteria so as to ensure the continued protection of classified uses, the Commission is aware of the fact that there may be a significant number of segments where temperature appears “elevated”, at least on a seasonal basis, in the absence of impacts from point source discharges or controllable nonpoint sources, yet the aquatic life use continues to be attained. In these cases of natural or irreversible human-induced elevated temperatures including those associated with the exercise of decreed water rights, the Commission desired that the Implementation Guidance Document identify an option to retain and protect the existing uses, but avoid the need for inappropriate section 303(d) listings. Thus, the Implementation Guidance Document would provide methods beyond a narrative standard for temperature that can be applied in such situations to site-specific waters, where there is a demonstration that elevated temperatures result from natural or irreversible human-induced impacts. 
Implementation in Discharge Permits 
Modifications were made to section 31.14 to record the Commission’s intentions regarding how the Colorado narrative temperature standards will be implemented in discharge permits. 
The Implementation Guidance Document will address issues related to spawning to be applied on a seasonal basis where the Division determines that the habitat that will be affected by the physical mixing zone is suitable for spawning by fish species that are expected to be present.  The Commission also determined that temperature effluent limits would not be required for discharges to effluent dependent or effluent dominated streams as long as there is no evidence that the aquatic life use may be negatively affected by the discharge.