COlorado department of public Health and environment
WATER QUALITY CONTROL COMMISSION
5 ccr 1002-33
CLASSIFICATIONS AND NUMERIC STANDARDS
FOR
UPPER COLORADO RIVER BASIN AND
NORTH PLATTE RIVER (PLANNING REGION 12)
REGULATION NO. 33
33.1	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.
33.2	PURPOSE
These regulations establish classifications and numeric standards for the Colorado River, the Yampa River, and the North Platte River, including all tributaries and standing bodies of water as indicated in section 33.6.  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 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.
33.3	INTRODUCTION
These regulations and tables present the classifications and numeric standards assigned to stream segments listed in the attached tables (See section 33.6).  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 33.6.  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 Standards and Methodologies for Surface Water.
33.4	DEFINITIONS
See the Colorado Water Quality Control Act and the codified water quality regulations for definitions.
33.5	BASIC STANDARDS
(1)	TEMPERATURE
All waters of Region 12 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.  
(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 and are applied to Aquatic Life class 2 streams on a case-by-case basis as shown in the tables in 33.6.  The column in the tables at 31.11 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 33.6.
(3)	URANIUM
(a)	All waters of the Upper Colorado 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 16.8-30 ug/l or naturally-occurring concentrations (as determined by the State of Colorado), whichever is greater.
(i)	The first number in the 16.8-30 ug/l range is a strictly health-based value, based on the Commission’s established methodology for human health-based standards. The second number in the range is a maximum contaminant level, established under the federal Safe Drinking Water Act that has been determined to be an acceptable level of this chemical in public water supplies, taking treatability and laboratory detection limits into account. Control requirements, such as discharge permit effluent limitations, shall be established using the first number in the range as the ambient water quality target, provided that no effluent limitation shall require an “end-of-pipe” discharge level more restrictive than the second number in the range. Water bodies will be considered in attainment of this standard, and not included on the Section 303(d) List, so long as the existing ambient quality does not exceed the second number in the range.
 (4)	 NUTRIENTS
Prior to May 31, 2022, interim nutrient values will be considered for adoption only in the limited circumstances defined at 31.17(e).  These circumstances include headwaters, Direct Use Water Supply (DUWS) Lakes and Reservoirs, and other special circumstances determined by the Commission.  Additionally, prior to May 31, 2017, only total phosphorus and chlorophyll a will be considered for adoption.  After May 31, 2017, total nitrogen will be considered for adoption per the circumstances outlined in 31.17(e).
Prior to May 31, 2022, nutrient criteria will be adopted for headwaters on a segment by segment basis for the Upper Colorado and North Platte River Basins.  Moreover, pursuant to 31.17(e) nutrient standards will only be adopted for waters upstream of all permitted domestic wastewater treatment facilities discharging prior to May 31, 2012 or with preliminary effluent limits requested prior to May 31, 2012, and any non-domestic facilities subject to Regulation 85 effluent limits and discharging prior to May 31, 2012. The following is a list of all permitted domestic wastewater treatment facilities discharging prior to May 31, 2012 or with preliminary effluent limits requested prior to May 31, 2012, and any non-domestic facilities subject to Regulation 85 effluent limits and discharging prior to May 31, 2012 in the Upper Colorado and North Platte River Basins:  

Segment	Permittee	Facility name	Permit No.	
COUCUC03	Colorado Dept of Transportation	Grizzly Creek Res Area WWTF	COG588067	
COUCUC03	Rock Gardens MHP	Rock Gardens MHP & Campground	COG588083	
COUCUC03	Colorado Dept of Transportation	Hanging Lake Res Area WWTF	COG588076	
COUCUC03	Colorado Dept of Transportation	Bair Ranch Rest Area	COG588075	
COUCUC03	Hermes Group	Two Rivers Village Metro Dist WWTF	COG588070	
COUCUC03	Roundup River Ranch	Roundup River Ranch WWTF	COG588116	
COUCUC03	Hot Sulphur Springs Town of	Hot Sulphur Springs WWTF	COG588084	
COUCUC03	Allegient Management	Ouray Ranch Homeowners Assn WWTF	COG588041	
COUCUC06a	C Lazy U Ranch Holdings LLC % Triton Investment Co	C Lazy U Ranch, INC.	COG588072	
COUCUC06b	Three Lakes Water and Sanitation District	Willow Creek Lagoons	CO0037681	
COUCUC07b	Kremmling Sanitation District	Kremmling Sanitation Dist WWTF	CO0048437	
COUCUC10a	Winter Park Water and Sanitation District	Winter Park WSD WWTF	CO0026051	
COUCUC10a	Young Life Campaign Inc	Crooked Creek Ranch	CO0045411	
COUCUC10a	Colorado Mountain Resort Investors LLC	Devil’s Thumb Ranch	CO0046566	
COUCUC10a	Tabernash Meadows WSD	Tabernash Meadows WSD WWTF	CO0045501	
COUCUC10c	Fraser Town of	Upper Fraser Valley TP	CO0040142	
COUCUC10c	Granby Sanitation District	Granby Sanitation District	CO0020699	
COUCBL02a	Upper Blue Sanitation Dist	Iowa Hill Water Reclamation	CO0045420	
COUCBL08	Dundee Realty USA  LLC	Arapahoe Basin Ski Area	CO0023876	
COUCBL13	Copper Mountain Consolidated Metro Dist	Copper Mtn Cons Metro District	CO0021598	
COUCBL17	Silverthorne/Dillon Joint Sewer Authority	Blue River WWTF	CO0020826	
COUCBL22	Frisco Sanitation District	Frisco Sanitation District WWTF	CO0020451	
COUCBL22	Snake River WWTF	Summit County Snake River WWTP	CO0029955	
COUCBL22	Upper Blue Sanitation District	Farmers Korner WWTF	CO0021539	
COUCEA02	Red Cliff Town of	Red Cliff Town of WWTP	CO0021385	
COUCEA08	Eagle River WSD	Vail WWTF	CO0021369	
COUCEA09a	Eagle River Water & Sanitation Dist	Avon WWTP	CO0024431	
COUCEA09a	Eagle River Water & San Dist	Edwards WWTF	CO0037311	
COUCEA09b	Eagle Town of	Eagle Town of WWTP	CO0048241	
COUCEA09b	Gypsum Town of	Gypsum Town of WWTF	CO0048830	
COUCRF03a	Aspen Consolidated Sanitation District	Aspen Consolidated San District	CO0026387	
COUCRF03a	Woody Creek Mobile HOA	Woody Creek Mobile Home Park	COG588103	
COUCRF03a	Aspen Village Inc c/o Independence Environmental Services	Aspen Village, INC.	COG588085	
COUCRF03a	Riversbend HOA	Riverbend Apartments	COG588066	
COUCRF03a	Independence Environmental Services	Lazy Glen Homeowners Assoc.	COG588049	
COUCRF03a	Basalt SD	Basalt Sanitation District	COG588063	
COUCRF03a	Ranch at Roaring Fork c/o Independence Environmental Services	Ranch at Roaring Fork HOA	COG588051	
COUCRF03a	Carbondale Town of	Carbondale Town of	COG588050	
COUCRF03a	Roaring Fork Water and San District	Roaring Fork WSD WWTF	CO0044750	
COUCRF03a	Spring Valley SD	Spring Valley SD WWTF	CO0046124	
COUCRF03a	Oak Meadows Service Company	Oak Meadows WWTF	CO0045802	
COUCRF03c	Sunlight Inc	Sunlight, INC.	CO0038598	
COUCRF03c	Mid Valley Metro District	Mid Valley Metro Dist WWTF	COG588105	
COUCRF03c	Blue Creek Ranch LLC	Blue Creek Ranch	COG588074	
COUCRF03c	H Lazy F LLC	H Lazy F MHP WWTF	COG588035	
COUCRF03c	El Rocko Mobile Home Park	El Rocko MHP	COG588029	
COUCRF04	Snowmass WSD	Snowmass WSD	CO0023086	
COUCRF08	Sopris Engineering LLC	Redstone Castle WWTF	COG588115	
COUCRF08	Redstone WSD	Redstone WSD WWTF	CO0046370	
COUCNP05b	Walden Town of	Walden Town of WWTF	CO0020788	
COUCYA02a	Yampa  Town of	Yampa WWTF	CO0030635	
COUCYA02a	Routt County	Milner Community WWTF	CO0047449	
COUCYA02c	Hayden Town of	Hayden Town WWTF	CO0040959	
COUCYA02c	Steamboat Springs City of	Steamboat Springs, City of	CO0020834	
COUCYA03	Whiteman School	Whiteman School	CO0031062	
COUCYA04	Routt County Phippsburg/Dept of Envir Hlth	Routt CO for Phippsburg Comm WWTF	COG589026	
COUCYA07	Oak Creek Town of	Oak Creek, Town of	CO0041106	
COUCYA022	Morrison Creek Metropolitan Water and Sanitation District	Morrison Creek Metro WWTF	CO0022969	
COUCYA022	Steamboat Lake Water and Sanitation Dist	Steamboat Lake Water & Sanitation Dist WWTF	CO0035556	
Prior to May 31, 2022:
•	For segments located entirely above these facilities, nutrient standards apply to the entire segment.  
•	For segments with portions downstream of these facilities, nutrient standards only apply above these facilities.  A footnote “C” was added to the total phosphorus and chlorophyll a standards in these segments. The footnote references the table of qualified facilities at 33.5(4). 
•	For segments located entirely below these facilities, nutrient standards do not apply.
A footnote “B” was added to the total phosphorus and chlorophyll a standards in lakes segments as nutrients standards apply only to lakes and reservoirs larger than 25 acres surface area. 
33.6	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 31.16.  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:
(a)	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
oC	=	degrees celsius
Cd	=	cadmium
ch	=	chronic (30-day) 
Chla	=	Chlorophyll a
Cl	=	chloride
Cl2	=	residual chlorine
CL	=	cold lake temperature tier
CLL	=	cold large lake temperature tier
CN	=	free cyanide
CrIII	=	trivalent chromium
CrVI	=	hexavalent chromium
CS-I	=	cold stream temperature tier one
CS-II	=	cold stream temperature tier two
Cu	=	copper
dis	=	dissolved
DM	=	daily maximum
DUWS	=	direct use water supply
D.O.	=	dissolved oxygen
F	=	fluoride
Fe	=	iron
Hg	=	mercury
mg/l	=	milligrams per liter
ml	=	milliliters
Mn	=	manganese
Mo	=	molybdenum
MWAT	=	maximum weekly average temperature
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	=	sculpin
Se	=	selenium
SO4	=	sulfate
sp	=	spawning
T	=	temperature
Tl	=	thallium
Tot	=	total
tr	=	trout
Trec	=	total recoverable
TVS	=	table value standard
U	=	uranium
ug/l	=	micrograms per liter
UP	=	use-protected
WAT	=	weekly average temperature
WL	=	warm lake temperature tier
WS	=	water supply
WS-I	=	warm stream temperature tier one
WS-II	=	warm stream temperature tier two
WS-III	=	warm stream temperature tier three
WS-IV	=	warm stream temperature tier four
Zn	=	zinc
(b)	In addition, the following abbreviations were 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:
(I)	existing quality as of January 1, 2000; or
(ii)	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.
(c)	As used in the Temporary Modifications and Qualifiers column of the tables in 33.6(5), the term “type A” refers to a Temporary Modification adopted pursuant to subsection 31.7(3)(a)(ii)(A) of the Basic Standards and Methodologies for Surface Water (i.e., “there is significant uncertainty regarding the water quality standard necessary to protect current and/or future use”).  As used in the Temporary Modifications and Qualifiers column of the tables in 33.6(5), the term “type B” refers to a Temporary Modification adopted pursuant to subsection 31.7(3)(a)(ii)(B) of the Basic Standards and Methodologies for Surface Water (i.e., “there is significant uncertainty regarding the extent to which existing quality is the result of natural or irreversible human-induced conditions”).
(d)	Temporary Modification for Water + Fish Chronic Arsenic Standard
(i)	The temporary modification for chronic arsenic standards applied to segments with an arsenic standard of 0.02 ug/l that has been set to protect the Water+Fish qualifier is listed in the temporary modification and qualifiers column as As(ch)=hybrid.
(ii)	For discharges existing on or before 6/1/2013, the temporary modification is:  As(ch)=current condition, expiring on 12/31/2021.
(iii)	For new or increased discharges commencing on or after 6/1/2013, the temporary modification is:  As(ch)=0.02-3.0 ug/l (Trec), expiring on 12/31/2021.
(a)	The first number in the range is the health-based water quality standard previously adopted by the Commission for the segment.
(b)	The second number in the range is a technology based value established by the Commission for the purpose of this temporary modification.
(c)	Control requirements, such as discharge permit effluent limitations, shall be established using the first number in the range as the ambient water quality target, provided that no effluent limitation shall require an “end-of-pipe” discharge level more restrictive than the second number in the range.
(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 ug/l unless noted)
PARAMETER(1)	TABLE VALUE STANDARDS (2)(3)	
Aluminum (Trec)
	Acute = e(1.3695[ln(hardness)]+1.8308)
pH equal to or greater than 7.0
          Chronic=e(1.3695[ln(hardness)]-0.1158)
pH less than 7.0
          Chronic= e(1.3695[ln(hardness)]-0.1158) or 87, whichever is more stringent	
Ammonia (4)	Cold Water = (mg/l as N)Total

	Warm Water = (mg/l as N)Total

	
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)	
Chromium VI(5)	Acute = 16
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= 1/2e(1.72[ln(hardness)]-6.52)
Chronic = e(1.72[ln(hardness)]-9.06)
Chronic(Trout) = e(1.72[ln(hardness)]-10.51)	
Temperature	temperature Tier	Tier CodE	Species Expected to BE PRESENT	Applicable Months	Temperature Standard (oC)	
					(MWAT)	(DM)	
	Cold Stream Tier I	CS-I	brook trout, cutthroat trout	June – Sept.	17.0	21.7	
				Oct. – May	9.0	13.0	
	Cold Stream Tier II	CS-II	all other cold-water species	April – Oct.	18. 3	23.9	
				Nov. – March	9.0	13.0	
	Cold Lake	CL	brook trout, brown trout, cutthroat trout, lake trout, rainbow trout, Arctic grayling, sockeye salmon	April –  Dec.	17.0	21.2	
				Jan. – March	9.0	13.0	
	Cold Large Lake (>100)	CLL	brown trout, lake trout, rainbow trout	April –  Dec.	18.3	23.8	
				Jan. – March	9.0	13.0	
	Warm Stream Tier I	WS-I	common shiner, Johnny darter, orangethroat darter	March – Nov.	24.2	29.0	
				Dec. – Feb.	12.1	14.5	
	Warm Stream Tier II	WS-II	brook stickleback, central stoneroller, creek chub, longnose dace, Northern redbelly dace, finescale dace, razorback sucker, white sucker	March – Nov.	27.5	28.6	
				Dec. – Feb.	13.8	14.3	
	Warm Stream Tier III	WS-III	all other warm-water species	March – Nov.	28.7	31.8	
				Dec. – Feb.	14.3	15.9	
	Warm Lakes	WL	yellow perch, walleye, pumpkinseed, smallmouth bass, striped bass, white bass, largemouth bass, bluegill, spottail shiner, Northern pike, tiger muskellunge, black crappie, common carp, gizzard shad, sauger, white crappie, wiper.	April – Dec.	26.3	29.5	
				Jan. – March	13.2	14.8	
Uranium	Acute= e(1.1021[ln(hardness)]+2.7088)
Chronic= e(1.1021[ln(hardness)]+2.2382)	
Zinc	Acute = 0.978*e(0.9094[ln(hardness)]+0.9095)
Chronic = 0.986*e (0.9094[ln(hardness)]+0.6235)
if hardness less than 102 mg/l CaCO3
Chronic (sculpin) = e(2.140[ln(hardness)]-5.084)	
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 400 mg/L, except for aluminum for which hardness shall be no greater than 220 mg/L.  The hardness values used in calculating the appropriate metal standard should be based on the lower 95 percent 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)	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 50 ug/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.
(4)	Assessment Criteria
The following criteria shall be used when assessing whether a specified waterbody is in attainment of the specified standard. 
(a)	Yampa River Segment 13d, Dry Creek: Iron Assessment Thresholds and Locations 
Mar-Apr, Fe(ch) = 3040(Trec), snowmelt season median values
May-Feb, Fe(ch) = 1110(Trec), no-snowmelt season median values
Assessment locations: 
•	Seneca II-W Stream Site 7 on Hubberson Gulch (WSH7): located in the middle reaches of Hubberson Gulch
•	Seneca II-W Flume Site 1 on Hubberson Gulch (WSHF1): located on Hubberson Gulch just upstream of its confluence with Dry Creek
•	Seneca II-W Stream Site 5 on Dry Creek (WSD5): located in the middle reaches of Dry Creek
(b)	Yampa River Segment 13e, Sage Creek: Iron Assessment Thresholds and Locations 
Fe(ch) = 1250(Trec), median of all data
Assessment locations: 
•	Yoast Stream Site 2 on Sage Creek (YSS2): located upstream of the west border of Section 18, T5N, R87W
Fe(ch) = 1000(Trec), median of all data
Assessment locations: 
•	Seneca II-W Stream Site 3 on Sage Creek (WSSF3): located downstream of the west border of Section 18, T5N, R87W
	(c)	Yampa River Segment 13b: Iron Assessment Thresholds and Locations
		Middle Creek-
		Mar-Jun, Fe(ch) = 2090(Trec), median of all data
		Jul-Feb, Fe(ch) = 1000 (Trec)
		Foidel Creek, Fe(ch) = 1000(Trec), median of all data
		Assessment locations:
•	Middle Creek Site G-MC-2/Site 29: located at N40° 23’ 48.3”, W106° 58’ 47.0”
•	Foidel Creek Site 14: located at N40° 33’ 48.6”, W107° 08’ 63.5”
•	Foidel Creek Site 8: located at N40° 21’ 55.7”, W107° 02’ 43.6”
•	Foidel Creek Site 900: located at N40° 23’ 24.7”, W106° 59’ 40.9”
. . . .
33.52	STATEMENT OF BASIS SPECIFIC STATUTORY AUTHORITY AND PURPOSE JUNE 9, 2014 RULEMAKING; FINAL ACTION AUGUST 11, 2014; EFFECTIVE DATE DECEMBER 31, 2014
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
The Commission deleted, renumbered, and/or created new segments to facilitate appropriate organization of waterbodies in this regulation.  The following changes were made:
Upper Colorado River Segment 5: This segment was deleted and the lakes and reservoirs in this segment were moved to a new Segment 13 at the end of the subbasin to be consistent with the organization of lakes and reservoirs segments in other basins.
Blue River Segment 1: Based on the information presented by the Upper Blue Sanitation District (UBSD), the mainstem of the Blue River from the confluence with the Swan River to Dillon Reservoir was moved to new Segment 2c to simplify the segmentation of the Upper Blue River and to facilitate the adoption of appropriate nutrient standards.  
Blue River Segment 3: This segment was deleted and the lakes and reservoirs in this segment were moved to a new Segment 22 at the end of the subbasin to be consistent with the organization of lakes and reservoirs segments in other basins.  The waters previously in Segment 22 were renumbered to Segment 23 as a result.
Eagle River Segments 9a and 9b:  The lower portion of Eagle River Segment 9a, the mainstem of the Eagle River from a point immediately below Squaw Creek to a point immediately below Rube Creek, was moved to a new Segment 9b to facilitate the adoption of appropriate temperature standards.  Segment 9b was renumbered to 9c to facilitate this change.
Roaring Fork River Segment 3d:  The following waters were moved from existing Segment 3a to a new Segment 3d: Cattle Creek, including all tributaries and wetlands, from the source to the most downstream White River National Forest boundary (39.467850, -107.065410).  These waters were split into different segments to facilitate the adoption of an Outstanding Waters designation for Segment 3d.
Roaring Fork River Segment 10a and 10b: The following waters were moved from existing Segment 10 to a new Segment 10b: Mainstem of North Thompson Creek, including all tributaries and wetlands, from the source to the White River National Forest boundary (39.316522,-107.305749). Mainstem of Middle Thompson Creek, including all tributaries and wetlands, from the source to a point immediately below the confluence with the South Branch of Middle Thompson Creek (39.295749, -107.308788). These waters were split into different segments to facilitate the adoption of an Outstanding Waters designation for Segment 10b. 
Yampa River Segment 1b: The lakes and reservoirs in this segment were moved to a new Segment 21 at the end of the subbasin to be consistent with the organization of lakes and reservoirs segments in other basins. Segment 1a was also changed to Segment 1 as a result.
Yampa River Segment 2b: The lakes and reservoirs in this segment were moved to a new Segment 22 at the end of the subbasin to be consistent with the organization of lakes and reservoirs segments in other basins.  Segment 2c was also changed to Segment 2b as a result.
Yampa River Segments 6 and 7:  The boundary of these two segments did not change, but the description was altered as it is not the Commission’s practice to use the location of an outfall as a segment boundary.  The boundary is now described as “a point 0.25 mile below County Road 27” instead of “the point of discharge of the Oak Creek wastewater treatment plant.”
Yampa River Segments 13b, 13d, 13e, 13g, 13h, 13i, 13j: The Commission created new segments for a number of segments in the Yampa River sub-basin. Seneca Coal, Peabody Sage Creek Mining LLC, and Twentymile Coal, LLC collected seasonal water quality and biomonitoring data over two years from multiple drainages within Yampa River segments 13b, 13d, 13e.  The upper reaches of segments 13b, 13d, and 13e (i.e., Cow Camp Creek, Bond Creek, Little Grassy Creek, Grassy Creek, Sage Creek, and Dry Creek) only flow seasonally, largely in response to spring snowmelt (March – July); the remainder of the year flow is greatly limited.  The lower reaches of these segments have limited flow as well; spring flows are consistent, but summer and fall streamflow is primarily restricted to small sections of flowing water and/or isolated pools, likely freezing over in the winter months.  The only exceptions to this flow regime are the mainstems of Fish, Foidel, and Middle Creeks, which normally maintain flow year-round, and select locations within lower Dry and Grassy Creeks which maintain sufficient pools to support hold-over populations of fish.  The reaches of the steams with ephemeral flows have been included in segments 13d, 13e, 13g, 13h, 13i.  The streams with perennial flows have been included in segments 13b and 13j.
Yampa River Segments 22 and 23: Elkhead Reservoir was moved to a new Segment 23.  These waters were split into different segments to facilitate a revision of the Aquatic Life use from Cold 1 to Warm 1.
The following segment descriptions were edited to improve clarity, correct typographical errors, and correct spelling errors:
Upper Colorado River Segment: 6c and 13
Blue River Segment:  8 and 6b
Eagle River Segments: 2, 5a and 11
Yampa River Segments: 8, 14, 15 and 18
B.	Revised Aquatic-Life Use Classifications 
Yampa River Segment 23:  Based on a Use Attainability Analysis (UAA) prepared by Colorado Parks and Wildlife and the Colorado River Water Conservation District, the Commission adopted a change in the Aquatic Life use classification and standard from Cold 1 to Warm 1 and a new Yampa River Segment 23 for Elkhead Reservoir.  Available temperature and fish data identify that the original classification of Elkhead Reservoir as a cold water lake was in error and that only warm water species are expected to occur due to natural and man-induced irreversible conditions. 
Yampa River Segments 13b, 13g:  Based on fish species expected to be present, temperature data, and other available evidence in a Use Attainability Analysis submitted by Seneca Coal, Inc., the Commission changed the aquatic life use classification for Yampa River segment 13b from Cold 1 to Warm 1.  For Segment 13g the Commission maintained the aquatic life use classification of Warm 1.  The Commission found that this was necessary to protect the fish collected in tributaries to Fish Creek in segment 13g, which included a round tail chub, a species that has been designated by Colorado Parks and Wildlife as a species of special concern.  It is likely that the chub and other species use the streams in 13g when flow and habitat are present. Segments 13h, 13i, and 13j inherited their aquatic life use classifications as a result of re-segmentation.
C.	Recreation Classifications and Standards
A review of the segments with an existing Recreation use classification showed that one segment had an incorrect E. coli standard to protect that use. The E. coli standard was corrected for the following segment: 
Upper Colorado River Segment: 6a  
D.	Water Supply Use Classification and Standards
The Commission added a Water Supply use classification and standards where the evidence demonstrated a reasonable potential for a hydrological connection between surface water and alluvial wells used for drinking water.  The Water Supply use classification and standards were added to the following segments:
Roaring Fork River Segment: 4
North Platte River Segment: 6
Yampa River Segment: 7
Numerous segments were missing the “(dis)” notation for the manganese water supply standard.  These errors were corrected to “Mn(ch)=WS(dis)”.
A molybdenum standard of 210 ug/l was applied to the following segments to protect the Water Supply use classification:
Blue River Segments:  14 and 15
Blue River Segment 13: The Commission adopted a narrative standard for segment 13 to protect water supply uses in downstream waters. It is the Commission’s intent that permit effluent limits for sources in segment 13 are written to protect downstream uses.   
E.	Agriculture Standards
Molybdenum:  In 2010, the Commission adopted a new standard for molybdenum to protect cattle from the effects of molybdenosis.  The table value adopted at that time was 300 ug/l, but included an assumption of 48 mg/day of copper supplementation to ameliorate the effects of molybdenosis.  State and local experts on cattle nutrition indicated that copper supplementation in the region is common, but is not universal.  Therefore, copper supplementation assumption was removed from the equation, which yields a standard of 160 ug/l.   The Commission expects that this value may be revised when data on the copper and molybdenum content of local forage becomes available.  The Commission also notes that in light of EPA’s disapproval of the 300 ug/l table value in the Basic Standards and Methodologies for Surface Water, the Commission intends to review this value during the next Basic Standards triennial review.
The Agriculture table value assumes that the safe copper:molybdenum ratio is 4:1. Food and water intake is based on a 273 kg (600 lb) feeder steer consuming 6.8 kg/day of dry matter and 20% of its body weight in water per day. Total copper and molybdenum intakes are calculated from the following equations: 
Cu intake mg/day = [([Cu] forage, mg/kg) x (forage intake, kg/day)] + [([Cu] water, mg/l) x (water intake, L/day)] + (Cu supplementation, mg/day) 
Mo intake mg/day = [([Mo] forage, mg/kg) x (forage intake, kg/day)] + [([Mo] water, mg/l) x (water intake, L/day)] + (Mo supplementation, mg/day) 
The assumed values for these equations are as follows: 
[Cu] forage = 7 mg/kg, [Mo] forage = 0.5 mg/kg, forage intake = 6.8 kg/day, [Cu] water = 0.008 mg/L, [Mo] water = 0.375 mg/L, water intake = 54.6 L/day, Cu supplementation = 0 mg/day, Mo supplementation = 0 mg/day. 
A molybdenum standard of 160 ug/l was adopted for the following segments in Regulation 33 that have an Agriculture use classification, and where livestock or irrigated forage are present or expected to be present.
Upper Colorado River Segments: 1, 2, 3, 4, 6a, 6b, 6c, 7a, 7b, 7c, 8, 9, 10a, 10b, 10c, 11, 12 and 13
Blue River Segments:  1, 2a, 2b, 2c, 4a, 4b, 5, 6a, 6b, 8, 9, 10, 11, 12, 16, 17, 18, 19, 20, 21, 22 and 23
Eagle River Segments: 1, 2, 3, 4, 5a, 5b, 5c, 6, 7a, 7b, 8, 9a, 9b, 9c, 10a, 10b, 11, 12, 13 and 14
Roaring Fork River Segments: 1, 2, 3a, 3b, 3c, 3d, 4, 5, 6, 7, 8, 9, 10a, 10b, 11 and 12
North Platte River Segments: 1, 2, 3, 4a, 4b, 5a, 5b, 6, 7a, 7b, 8 and 9
Yampa River Segments: 1, 2a, 2b, 3, 4, 5, 6, 7, 8, 11, 12, 13a, 13b, 13c, 13d, 13e, 13f, 13g, 13h, 13i, 13j, 14, 15, 18, 19, 20a, 20b, 21, 22, and 23
The following segments have an Agriculture use classification, but livestock or irrigated forage are not expected to be present.  A molybdenum standard of 160 ug/l was not applied to these segments to protect the Agriculture use classification:
Blue River Segments:  13, 14 and 15
Upper Colorado Segment 8:  A site-specific molybdenum standard of 190 ug/l was adopted for this segment, which has an Agriculture use classification, and livestock and irrigated forage are present or expected to be present.   This site-specific molybdenum standard is based on protection of a lactating cow (409 kg), which is the animal and life stage that is most sensitive to molybdenum, and site-specific factors appropriate for the Williams Fork area.  The equation above and in the Regulation #31 Statement of Basis (2010, 31.48 H) was used with the following dietary and water intake values :  [Cu] forage = 7 mg/kg, [Mo] forage = 0.5 mg/kg, forage intake = 10.2 kg/day (OSU, 2004), [Cu] water = 0.008 mg/L, [Mo] water = 0.375 mg/L, Cu supplementation = 0 mg/day, Mo supplementation = 0 mg/day.  Water intake = 67.8 L/day (NRC, 2000), based on an ambient temperature of 80oC (ave. daily max. at Kremmling, CO).
F.	Changes to Antidegradation Designation
Roaring Fork Segment 3d: The Commission adopted an Outstanding Waters (OW) designation for this segment based on evidence presented by WildEarth Guardians showing that water quality meets the requirements of 31.8(2)(a).  The presence of designated Critical Cutthroat Trout Habitat by the State of Colorado proves the exceptional recreational or ecological significance of the waters. Outreach conducted by WildEarth Guardians demonstrated support for the change in designation, the outstanding nature of these waters and the need for the additional protection of the outstanding waters designation. 
The Commission understands that existing land uses, including grazing, are in place in these watersheds. The evidence demonstrates that these existing land uses are compatible with the OW designation since the current high level of water quality has been attained with these uses in place. It is the Commission’s intent that this OW designation should not be used to establish additional permit requirements for existing uses within this area. 
Roaring Fork Segment 10b:  The Commission adopted an Outstanding Waters (OW) designation for this segment based on evidence presented by Trout Unlimited showing that the criteria of 31.8(2)a has been met for these waters. In addition to meeting the water quality requirements of 31.8(2)a, these waters support Colorado River cutthroat trout, including key conservation populations in North and Middle Thompson Creek. The Colorado River cutthroat trout is listed as a species of concern in Colorado and is subject to a conservation agreement to prevent potential federal Endangered Species Act listing. The Commission notes that the outreach undertaken by Trout Unlimited as proponent of this designation helps to demonstrate broad support for the conclusion that these waters constitute an outstanding natural resource and that the additional protection provided by this designation is appropriate. 
The Commission understands that existing land uses, including grazing, are in place in these watersheds. The evidence demonstrates that these existing land uses are compatible with the OW designation since the current high level of water quality has been attained with these uses in place. It is the Commission’s intent that this OW designation should not be used to establish additional permit requirements for existing uses within this area. 
Yampa River Segments 13d, 13e, 13h, 13i, and 13j: The Commission retained use protected designation for segments 13d and 13e, and segments 13h, 13i, and 13j inherited their use protected designations as a result of re-segmentation.
G.	Ambient Standards
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.  In some cases, new ambient standards were adopted.  The following segments have ambient-based standards that were revised:
Upper Colorado River Segments: 12 (Lake Granby) and 13 (Wolford Mountain)
North Platte River Segment: 9 (Lake John) 
Yampa River Segments: 13b (Middle Creek) and 22 (Stagecoach Reservoir)
New ambient based standards were adopted for the following segments:
North Platte River Segment: 9 (South Delaney Lake) 
Yampa River Segment: 2b (Pearl Lake) 
Yampa River Segment 13b: Foidel Creek is achieving the table value standard for total recoverable iron which is 1000 ug/L with assessment locations specified in 33.6(4)(c), which the Commission adopted due to spatial variability in iron concentrations throughout the stream reach. Accordingly the Commission retained the 1000 ug/L total recoverable iron standard for Foidel Creek.  The Commission updated the annual ambient-based standard on Middle Creek to a seasonal ambient-based standard for March-June of  2090 ug/L, based on the most recent five years of data. TVS applies for the remainder of the year for Middle Creek.
Yampa River Segments 13h and 13j: While the Commission did not adopt ambient based selenium standards proposed in this hearing on these segments, parties are encouraged to collect additional data to further evaluate the appropriateness of an ambient based selenium standard in the future. 
H.	Aquatic Life Ammonia and Metals Standards
New Table Value Standards:  The zinc, zinc sculpin, and aluminum table values were revised in the 2010 Basic Standards hearing.  The acute and chronic zinc, zinc sculpin, and aluminum equations in 33.6(3) were modified to conform to Regulation 31.  The footnotes to the table values in 33.6(3) were renumbered to match the appropriate references.  Footnote (4 old) was deleted and a new footnote 4 was added.  
Zinc sculpin standards:  In low-hardness situations (hardness below 102 mg/l), the zinc equation is not protective of mottled sculpin (Cottus bairdi), a native west-slope fish species. A review of existing hardness and fishery data showed numerous segments with low average hardness (<102 CaCO3 mg/l) and where the Colorado Division of Parks and Wildlife expects sculpin to be present.  A sculpin-specific zinc equation was added to the following segments:
Blue River Segments: 13 and 18
Eagle River Segment: 3
Roaring Fork River Segment: 7
Yampa River Segment: 1
For the following segments where hardness could exceed 102 mg/l, both the zinc sculpin standard and the chronic zinc table value standard were adopted:
Upper Colorado River Segments:  1, 2, 3, 7b, 8, 10a, 10b and 10c
Blue River Segments:  1, 4a, 4b, 8, 14 and 17
Eagle River Segments:  1, 2, 4, 6, 7a and 8
Roaring Fork River Segments:  2, 5, 6, 10a and 10b
Yampa River Segments: 2a, 2b, 3, 8, 13a, 18 and 19
I.	Uranium Standards
At the 2010 Basic Standards rulemaking hearing, the Commission changed the Water Supply table value for uranium from 30 ug/l to a hyphenated standard of 16.8-30 ug/l.  The Commission revised the language in 33.5(3)(c) to reflect the change to the basin-wide standard.  A new section 33.5(3)(c)(i) was added to explain the hyphenated standard.  Subsection 33.5(3)(d) was deleted because it was redundant with 33.5(3)(c).
J.	Temporary Modifications
To remain consistent with the Commission’s decisions regarding arsenic at 33.50, all existing temporary modifications for arsenic of “As(ch)=hybrid” (expiration date of 12/31/21) were retained.  An arsenic temporary modification was added to the following segments, which had an existing or newly added chronic arsenic standard of 0.02 ug/l and a permitted discharger with a predicted water quality–based effluent limit compliance problem:
Upper Colorado River Segment: 10c
Roaring Fork River Segment: 4
Yampa River Segment: 7 
Where the Commission has adopted a narrative temporary modification of “current condition”, the Commission intends that, when implementing the temporary modification in a CDPS permit, the permit conditions will reflect the current effluent quality, recognizing that it changes over time due to seasonal variability, change in the influent flow and the concentration over time.
Iron
Yampa River Segments 13d and 13i: The Commission adopted a narrative temporary modification for iron on the former segment 13e in the 2008 basin hearing and the temporary modification has remained in place.  Since that time Peabody has been working on resolving the uncertainty surrounding the appropriate underlying standard. The Commission adopted a current conditions narrative temporary modifications on segments 13d and 13i (13i is a new segment that was formerly a part of 13e) until December 31, 2016.  The Commission expects that Peabody will work with the Division and other interested stakeholders to develop a definitive plan to resolve the uncertainty for these segments for the December 2014 temporary modification hearing.
Selenium
Yampa River Segments 13b, 13d, 13e, 13g, 13i: Seneca Coal, Peabody, and Twentymile originally proposed numeric fish tissue-based site-specific standards for selenium for Yampa River segments 13b, 13d, 13e, 13g and 13i.  In support of their proposal they provided data including in-stream selenium concentration and fish-tissue selenium concentrations along with proposed implementation methodologies.  However, during the rulemaking process EPA issued new draft selenium criteria.  In response to EPA’s May 2014 draft selenium criteria, Seneca Coal, Peabody, and Twentymile withdrew their site-specific standard proposal and revised their proposal to a narrative “current conditions” temporary modification for selenium for these segments.   
The Commission adopted a current conditions temporary modification for selenium for these segments. Peabody presented information that shows a demonstrated or predicted compliance problem for each of these segments.  Additionally, the Commission found there was significant uncertainty regarding the water quality standard necessary to protect current and/or future uses, and that there is substantial uncertainty about the extent to which existing quality is the result of natural or irreversible human-induced conditions. 
Molybdenum
Blue River Segment 14:  The Commission adopted a temporary modification of the molybdenum standard for this segment of Mo(ch)=“current conditions” (Exp. 12/31/16).  The Commission recognizes that there is new toxicological information that should be included in recalculation of a human health-based criterion.  Parties do not agree on the uncertainty factors that need to be included in the calculations. Since this issue is larger than a segment-specific issue, it is more appropriate to address this situation in the review of the Basic Standards and the expiration date was set to accommodate that schedule.   There is also uncertainty regarding the extent to which existing quality in Blue River Segment 14 is the result of irreversible human-induced conditions due to forthcoming new treatment facilities at the Climax Mine.  Climax also presented information that shows a predicted compliance problem and has submitted an adequate plan for eliminating the need for the temporary modification.  
K.	Temperature
Ambient temperature standards for lakes 
In the 2008 triennial review, the WAT standard was found to be unattainable for a number of cold large lakes and reservoirs with apparently healthy cold-water fish populations. Because summertime temperature in the mixed layer for large lakes and reservoirs is very well correlated to the waterbody’s elevation, the Commission adopted ambient temperature standards for large lakes wherever data were available to characterize a WAT and the thermal characteristics of the lakes and reservoirs were determined to be the result of natural conditions. As a result of setting ambient temperature standards, the adequate refuge defined in Regulation 31, Table 1, footnote 5(c)(iii) was assessed using the site-specific temperature standard, and many lakes with obvious dissolved oxygen issues were considered to have adequate refuge.
Footnote 5(c)(iii) states: 
When a lake or reservoir is stratified, the mixed layer may exceed the criteria in Table 1 provided that an adequate refuge exists in water below the mixed layer. Adequate refuge depends on concurrent attainment of applicable dissolved oxygen standards. If the refuge is not adequate because of dissolved oxygen levels, the lake or reservoir may be included on the 303(d) List as “impaired” for dissolved oxygen, rather than for temperature. 
To ensure that adequate refuge is defined in a way that protects the Aquatic Life use, the Commission adopted footnote “D” which was applied to the temperature standard for deep stratified lakes. Footnote “D” states “Assessment of adequate refuge shall rely on the Cold Large Lake table value temperature criterion and applicable dissolved oxygen standard rather than the site-specific temperature standard”, and was applied to the following lake segments: 
Upper Colorado River Segment: 12 (Shadow Mountain and Lake Granby) 
Upper Colorado River Segment: 13 (Wolford Mountain and Williams Fork Reservoirs) 
Roaring Fork River Segment: 12 (Ruedi Reservoir) 
Yampa River Segment: 22 (Pearl Lake, Stagecoach and Steamboat Reservoirs) 
Eagle River Segments 8, 9a, 9b and 9c:  In the 2008 hearing, the Commission adopted temperature standards for Eagle River Segments 8 and 9a.  Due to the limited temperature and biological information available at the time, the Commission recognized that there was uncertainty regarding the appropriate temperature standards adopted in that hearing.  Since 2008, Eagle River Water and Sanitation District (ERWSD) has collected temperature data in Segments 8 and 9a and has worked with Colorado Parks and Wildlife (CPW) to determine the aquatic species expected to occur in Gore Creek and the Eagle River.
In this hearing, based on information presented by ERWSD and CPW, the Commission adopted site-specific temperature standards for Eagle River segments 8, 9a, and 9b to protect the aquatic life use (31.7(1)(b)(iii)) and re-segmentation where appropriate (Section A).  The spring shoulder season standards were adjusted to protect cutthroat trout spawning and incubation.  The fall shoulder season standards were adjusted to protect brook and brown trout migration and spawning. The basis for these temperature standards is specific to the temperature and biological conditions in the Eagle River Segments 8, 9a, and 9b, and accounts for the seasonal temperature requirements for the various life stages of the aquatic species expected to occur in this area while recognizing that these segments include a transitional zone between Cold Stream Tier I and Tier II.  This action is not intended to revise the biological goals for the Eagle River established by the Commission in 2008, regarding the Eagle Mine Superfund Site.  
The Commission recognizes the high quality fishery that exists in these segments is economically important, yet is currently stressed and in recovery.  Local stakeholders are actively working to protect and improve water quality including projects associated with urban runoff, stream and riparian restoration, hydrologic conditions, and the Eagle Mine Superfund Site.  Future refinements of temperature standards for these segments may be warranted as more information becomes available regarding their natural and existing thermal regimes, and the temperatures needed to protect the aquatic species expected to occur.  
Segment 8: The lower portion of this segment is currently designated a Gold Medal Fishery. Cutthroat, brook, brown and rainbow trout are all expected to occur in this segment.  The Commission adopted site-specific chronic temperature standards based on a modification of Cold Stream Tier I table values
Segment 9a:  This segment is impacted by metals contributions from historic mining.  Cutthroat, brook, rainbow, and brown trout could occur in this segment.  The Commission adopted site-specific chronic temperature standards based on a modification of Cold Stream Tier I table values.   
Segment 9b:   This segment is also impacted by metals contributions from historic mining.  Rainbow and brown trout are expected to occur in this segment, and this area is a transition zone.  Cutthroat and brook trout may use this segment seasonally, and when hydrologic conditions are favorable. The Commission adopted site-specific acute and chronic temperature standards based on a modification of Cold Stream Tier II table values.  
Segment 9c: Segment 9b was renumbered to segment 9c, and retained its use classifications and Cold Stream Tier II temperature standards.
Yampa River Segments 13b, 13d, 13e, 13g, 13h, 13i, and 13j: Based on fish species expected to be present, temperature data, and other available evidence submitted by Peabody, Warm Stream Tier II temperature standards were retained for segments 13d and 13e, and were adopted for segments 13b  and 13g.  Segments 13h, 13i, and 13j inherited their Warm Stream Tier II temperature standards as a result of re-segmentation.
 L.	Nutrients
In March 2012, the Commission adopted interim nutrient values in the Basic Standards (Regulation 31) and created a new statewide control regulation (Regulation 85) to address nutrients in Colorado.  Regulation 31.17 includes interim nutrient values for total phosphorus, total nitrogen, and chlorophyll a for both lakes and reservoirs, and rivers and streams. Due to the phased implementation approach adopted with these criteria (31.17(e)), the Commission adopted only total phosphorus and chlorophyll a standards at this time. Nitrogen standards were not considered as part of this rulemaking hearing, but will be considered in the next triennial review, currently scheduled for June, 2019. 
Total phosphorus and chlorophyll a standards were adopted for waters upstream of all permitted domestic wastewater treatment facilities discharging prior to May 31, 2012 or with preliminary effluent limits requested prior to May 31, 2012, and any non-domestic facilities subject to Regulation 85 effluent limits and discharging prior to May 31, 2012. A new section (4) was added at 33.5 describing implementation of the interim nutrient values into the tables at 33.6, and includes a table which lists these facilities and the segment to which they discharge.  
•	For segments located entirely above these facilities, nutrient standards apply to the entire segment.  
•	For segments with portions downstream of these facilities, nutrient standards only apply above these facilities. A footnote “C” was added to the total phosphorus and chlorophyll a standards in these segments. The footnote references the table of qualified facilities at 33.5(4). 
•	For segments located entirely below these facilities, nutrient standards do not apply.
•	For rivers and streams segments, total phosphorus standards were adopted above the dischargers listed at 33.5(4) for segments with an Aquatic Life use.  Chlorophyll a standards were adopted above the dischargers listed at 33.5(4) for segments with either an E, P, or U Recreation use classification.
•	For lakes and reservoirs segments, total phosphorus and chlorophyll standards were adopted with a footnote “B” as these standards only apply to waterbodies larger than 25 acres surface area.
31.17(e)(ii) also allows the Commission to adopt numeric nutrient standards for Direct Use Water Supply (DUWS) lakes and reservoirs.  No proposals were made by the Division to adopt standards based on this provision in this rulemaking.
31.17(e)(iii) also allows the Commission to adopt numeric nutrient standards for circumstances where the provisions of Regulation 85 are not adequate to protect waters from existing or potential nutrient pollution. No proposals were made to adopt standards based on this provision in this rulemaking.
Chlorophyll a standards were adopted for the following segments:
Upper Colorado River Segments: 1, 2, 3, 4, 6a, 7b, 8, 9, 10a, 11, 12 and 13
Blue River Segments:  1, 2a, 4a, 4b, 5, 6a, 6b, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 21, 22 and 23
Eagle River Segments: 1, 2, 3, 4, 6, 7a, 7b, 8, 10a, 10b, 11, 12, 13 and 14
Roaring Fork River Segments: 1, 2, 3a, 3c, 3d, 4, 5, 6, 7, 8, 9, 10a, 10b, 11 and 12
North Platte River Segments: 1, 2, 3, 4a, 4b, 5a, 8 and 9
Yampa River Segments: 1, 2a, 3, 5, 6, 7, 8, 13a, 13b, 13c, 13d, 13f, 13g, 13h, 14, 15, 18, 19, 20a, 21, 22 and 23
Total Phosphorus standards were adopted for the following segments:
Upper Colorado River Segments: 1, 2, 3, 4, 6a, 6b, 7a, 7b, 7c, 8, 9, 10a, 11, 12 and 13
Blue River Segments:  1, 2a, 4a, 4b, 5, 6a, 6b, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 18, 19, 20, 21, 22 and 23
Eagle River Segments: 1, 2, 3, 4, 6, 7a, 7b, 8, 10a, 10b, 11, 12, 13 and 14
Roaring Fork River Segments: 1, 2, 3a, 3b, 3c, 3d, 4, 5, 6, 7, 8, 9, 10a, 10b, 11 and 12
North Platte River Segments: 1, 2, 3, 4a, 4b, 5a, 5b, 6, 7a, 7b, 8 and 9
Yampa River Segments: 1, 2a, 3, 4, 5, 6, 7, 8, 11, 12, 13a, 13b, 13c, 13d, 13e, 13f, 13g, 13h, 13i, 13j, 14, 15, 18, 19, 20a, 20b, 21, 22 and 23
Blue River Segments 1, 2a, 2b and 2c:  Nutrient standards were adopted for Blue River Segment 1, as this segment is located entirely above qualified dischargers.  Nutrient standards were adopted with a footnote “C” for Segment 2a, as the Upper Blue Sanitation District’s (UBSD) Iowa Hill Water Reclamation Facility is a qualified discharger listed at 33.5(4) and is located within this segment.  Nutrient standards were not adopted for Blue River Segment 2b and new Segment 2c, as these segments are located entirely below the Iowa Hill Water Reclamation Facility and nutrient standards do not apply.  
The UBSD’s South Blue River wastewater treatment facility is located within Blue River Segment 1.  However, this facility discharges to groundwater and it is not subject to Regulation 85 nutrient limitations for surface water discharges.  It is therefore not a qualified discharger listed at 33.5(4).  If the nature of the discharge from UBSD’s South Blue River wastewater treatment facility changes to include a discharge to surface water, this issue will be revisited to reflect such a change.
M.	Direct Use Water Supply Sub-classification 
Also in the March 2012 rulemaking hearing, the Commission adopted a sub-classification of the Domestic Water Supply Use called “Direct Use Water Supply Lakes and Reservoirs Sub-classification” (Regulation 31, at 31.13(1)(d)(i)).  This sub-classification is for water supply lakes and reservoirs where there is a plant intake location in the lake or reservoir or a man-made conveyance from the lake or reservoir that is used regularly to provide raw water directly to a water treatment plant that treats and disinfects raw water.  In this action today, the Commission has begun to apply this sub-classification and anticipates that it will take several basin reviews to evaluate all the reservoirs in the basin.  The Commission adopted the DUWS sub-classification on the following reservoirs and added “DUWS” to the classification column in the standards tables.  The public water systems are listed along with the reservoirs and segments.
Upper Colorado River Segment 12:	Grand Lake (YMCA)
Upper Colorado River Segment 13:  	Ute Creek Reservoir (Climax – Henderson Mill)
Blue River Segment 22:  		Goose Pasture Tarn (Town of Breckenridge)
Roaring Fork River Segment 12: 	Leonard Thomas Reservoir (City of Aspen)
Roaring Fork River Segment 12:		Wildcat Reservoir (Wildcat Ranch)
Yampa River Segment 22:  		Steamboat Lake (Steamboat Lake State Park)
Yampa River Segment 22:  		Stagecoach Reservoir (Stagecoach State Park)
Yampa River Segment 22:  		Yampa River Holding Pond (PSCO OF CO - Hayden Station)
31.17(e)(iii) also allows the Commission to adopt numeric nutrient standards for Direct Use Water Supply (“DUWS”) lakes and reservoirs.  No standards were adopted based on this provision in this rulemaking.
N.	Chromium III Standards
A review of the chromium III standards showed that standards to protect the Aquatic Life use classification may not be protective of the Agriculture use in some high-hardness situations. A chromium III standard of CrIII(ch)=100(Trec) was added to segments with Aquatic Life and Agriculture use classifications, but no Water Supply use.  The acute chromium III standard associated with the Water Supply use is protective of the Agriculture use, but is not protective of the Aquatic Life use when hardness is less than 61 ug/l.  For segments that have both Aquatic Life and Water Supply use classifications, a chronic chromium III standard of CrIII(ch)=TVS was added to all segments that did not previously have that standard.  Changes were made to the following segments:
Upper Colorado River Segments: 3, 4, 6c, 7a, 7b, 7c, 9, 11, 12 and 13
Blue River Segments:  1, 6a, 6b, 11, 12, 13, 14, 16, 17, 19, 20, 21, 22 and 23
Eagle River Segments:  2, 3, 5a, 5b, 5c, 8, 9a, 9b, 9c, 10a, 10b, 12, 13 and 14
Roaring Fork River Segments: 1, 3a, 3b, 3c, 3d, 4, 6, 7, 8, 9, 10a, 10b, 11 and 12
North Platte River Segments: 3, 6, 7a, 7b, 8 and 9
Yampa River Segments:  2a, 2b, 5, 6, 7, 13a, 13b, 13c, 13d, 13e, 13f, 13g, 13h, 13i, 13j, 14, 15, 19, 20a, 20b, 21, 22 and 23
O.	Other Site-Specific Revisions
Upper Colorado River Segment 12:  The Commission determined in 2008 that the adoption of a 4 meter numerical standard with a delayed effective date was an appropriate policy choice to encourage cooperative efforts to improve Grand Lake clarity. At the same time, the Commission adopted the following narrative “The highest level of clarity attainable, consistent with the exercise of established water rights and the protection of aquatic life” as the effective standard. Efforts since 2008 have focused on data collection and understanding the factors controlling clarity. 
In today’s action, the Commission adopted a change to the narrative clarity standard that added “protection of water quality throughout the Three Lakes System” as another consideration for attainability in order to recognize the interdependence of water quality in the entire system. The Commission also decided that further delay in the effective date of the numerical standard was justified in view of the progress that has been made cooperatively by the parties and by the obstacles they have yet to overcome. 
Sufficient effort has not yet been focused on determining an “attainable” level of clarity that is consistent with the constraints identified in the narrative standard. It is the Commission’s hope that improvement in clarity can be achieved by a balanced approach that does not sacrifice water rights, the recreational fishery, or water quality. The Commission expects and anticipates a cooperative effort that will focus on identifying an attainable and protective Grand Lake clarity standard.  The effort should address the following questions that consider the constraints imposed on attainability: 
1)	What are the water rights constraints? 
2) 	What are the aquatic life constraints?
3)	What are the water quality constraints from the perspective of the Three Lakes system? 
4)	What are the financial constraints? 
The Commission expects that the cooperative effort will  also evaluate alternatives for describing the water transparency necessary to protect the assigned use classifications
Ultimately, the goal of the effort is to develop and propose by January 2016 an attainable and protective clarity standard for Grand Lake for consideration by the Commission. If this cooperative effort does not result in a proposal for an attainable and protective clarity standard by January 2016, the standard will be determined by a site specific clarity standard hearing to be scheduled for 2016. 
Blue River Segment 5:  The pH standard for Soda Creek was changed from 6.0-9.0 to the table value of 6.5-9.0, based on data demonstrating this value was currently being attained.
Eagle River Segment 11: The “(ac)” notation was deleted from the nitrite and nitrate standards for this segment.
Roaring Fork River Segment 3b: A footnote “A” was added to the chronic arsenic standard to explain the hyphenated standard.
Yampa River Segment 4: A footnote “A” was added to the chronic arsenic standard to explain the hyphenated standard.
Yampa River Segment 13d: A footnote “A” was added to the chronic arsenic standard to explain the hyphenated standard. 
PARTIES TO THE RULEMAKING HEARING
1.	Grand County, Northwest Colorado Council of Governments and Northern Colorado Water Conservancy District
2.	Eagle River Water and Sanitation District
3.	Trout Unlimited
4.	WildEarth Guardians
5.	Tri-State Generation and Transmission Association
6.	Seneca Coal Company, Peabody Sage Creek Mining, LLC, and Twentymile Coal Company
7.	Western Resource Advocates
8.	Colorado River Water Conservation District
9.	Climax Molybdenum Company
10.	Trapper Mining, Inc.
11.	Upper Blue Sanitation District
12.	Clinton Ditch & Reservoir Company
13.	Vail Resorts, Inc. and Vail Summit Resorts, Inc.
14.	Eagle Park Reservoir Company
15.	Upper Eagle Regional Water Authority
16.	Colorado Parks and Wildlife
17.	Denver Water
18.	Environmental Protection Agency
19.	Powdr-Copper Mountain, LLC
20.	Town of Frisco