Code of Colorado Regulations
1000 - Department of Public Health and Environment
1002 - Water Quality Control Commission (1002 Series)
5 CCR 1002-33 - REGULATION NO. 33 - CLASSIFICATIONS AND NUMERIC STANDARDS FOR UPPER COLORADO RIVER BASIN AND NORTH PLATTE RIVER (PLANNING REGION 12)
Section 5 CCR 1002-33.6 - TABLES

(a) The following abbreviations are used in this regulation and in the tables in Appendix 33-1:

(b) In addition, the following abbreviations were used:

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 chronic standards, as specified in the Basic Standards and Methodologies at 31.16 Table II and III:

(c) Temporary Modification for Water + Fish Chronic Arsenic Standard

(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. The "T" in the chronic equations stands for temperature.

(5) The acute(warm) cadmium equation applies to segments classified as Aquatic Life Warm Class 1 or 2. The acute(cold) cadmium equation applies to segments classified as Aquatic Life Cold Class 1 or 2.

(6) Unless the stable forms of chromium in a waterbody have been characterized and shown not to be predominantly chromium VI, data reported as the measurement of all valence states of chromium combined should be treated as chromium VI. In addition, in no case can the sum of the concentrations of chromium III and chromium VI or data reported as the measurement of all valence states of chromium combined exceed the water supply standards of 50 µg/L chromium in those waters classified for domestic water use.

(7) Selenium is a bioaccumulative metal and subject to a range of toxicity values depending upon numerous site-specific variables.

(8) Mountain whitefish-based summer temperature criteria [16.9 (ch), 21.2 (ac)] apply when and where spawning and sensitive early life stages of this species are known to occur.

(9) Lake trout-based summer temperature criteria [16.6 (ch), 22.4 (ac)] apply where appropriate and necessary to protect lake trout from thermal impacts.

____________________________________________________________________________________

(a) Upper Colorado River Segment 3: Temperature Standards

Upper Colorado from below the confluence with the Blue River to below the confluence with the Roaring Fork River.

DM = 21.2 and MWAT = 16.9 from 4/1 - 5/31

DM and MWAT = CS-II from 6/1 - 9/30

DM = 21.2 and MWAT = 16.9 from 10/1 - 10/31

DM and MWAT = CS-II from 11/1 - 3/31

All other locations DM and MWAT = CS-II

(b) Upper Colorado River Segment 7a: Temperature Standards Canyon Creek

DM = 21.2 and MWAT = 16.9 from 4/1 - 5/31

DM and MWAT = CS-II from 6/1 - 9/30

DM = 21.2 and MWAT = 16.9 from 10/1 - 10/31

DM and MWAT = CS-II from 11/1 - 3/31

All other locations DM and MWAT = CS-II

(c) Upper Colorado Segment 12: Temperature Standards

All locations DM and MWAT = CL,CLL from 1/31 - 3/31

Grand Lake DM = 22.4 and MWAT = 16.6 from 4/1 - 12/31

Lake Granby DM = 22.4 and MWAT = 19.6 from 4/1- 12/31

Shadow Mountain Reservoir DM = CLL and MWAT = 19.3 from 4/1 - 12/31

All other locations DM and MWAT = CL,CLL from 4/1 - 12/31

(d) Upper Colorado Segment 13: Temperature Standards

All locations DM and MWAT = CL,CLL from 1/31 - 3/31

Wolford Mountain Reservoir DM = CLL and MWAT = 21.3 from 4/1 - 12/31

Williams Fork Reservoir DM = 22.4 and MWAT = 21.6 from 4/1-12/31

Deep Lake DM = CL and MWAT = 16.6 from 4/1 - 12/31

All other locations DM and MWAT = CL/CLL from 4/1 - 12/31

(e) Roaring Fork River Segment 3c: Temperature Standards

DM = 21.2 and MWAT = 16.9 from 4/1 - 5/31

DM and MWAT = CS-II from 6/1 - 9/30

DM = 21.2 and MWAT = 16.9 from 10/1 - 10/31

DM and MWAT = CS-II from 11/1 - 3/31

(f) North Platte River Segment 9: Temperature Standards

All locations DM and MWAT = CL, CLL from 1/1 - 1/31

Lower Big Creek Lake and Upper Big Creek Lake DM = 22.4 and MWAT = 16.6 from 4/1 -12/31

Agua Fria Lake DM = CL and MWAT = 16.6 from 4/1 - 12/31

South Delaney Lake DM = CLL and MWAT = 18.8 from 4/1 - 12/31

North Delaney Lake DM = CLL and MWAT = 20.1 from 4/1 - 12/31

Lake John DM = CLL and MWAT = 21.2 from 4/1 - 12/31

All other locations DM and MWAT= CL,CLL from 4/1-12/31

(g) Yampa River Segment 2b: Temperature Standards

Yampa River from above the confluence with Oak Creek to below the confluence with Dry Creek.

DM = 21.2 and MWAT = 16.9 from 4/1 - 5/31

DM and MWAT = CS-II from 6/1 - 9/30

DM = 21.2 and MWAT = 16.9 from 10/1 - 10/31

DM and MWAT = CS-II from 11/1 - 3/31

Yampa River below confluence with Dry Creek DM and MWAT = CS-II

(h) Yampa River Segment 13b: Iron Standards and Assessment Locations Iron Standards:

Middle Creek:

March-June, Iron(chronic) = 2090(T),median of all data

July-February, Iron(chronic) = 1000(T)

Foidel Creek Iron(chronic) = 1000(T), median of all data

Iron Assessment Locations:

Middle Creek Site G-MC-2/Site 29: located at 40°23'48.3"N, 106°58'47.0"W.

Foidel Creek Site 14: located at 40°33'48.6"N, 107°08'63.5"W.

Foidel Creek Site 8: located at 40°21'55.7"N, W107°02'43.6"W.

Foidel Creek Site 900: located at 40°23'24.7"N, 106°59'40.9"W.

(i) Yampa River Segment 13b: Temperature Standards

Fish Creek

DM = 21.2 and MWAT = 16.9 from 4/1 - 5/31

DM and MWAT = WS-II from 6/1 - 9/30

DM = 21.2 and MWAT = 16.9 from 10/1 - 10/31

DM and MWAT = WS-II from 11/1 - 3/31

All other locations DM and MWAT = WS-II

(j) Yampa River Segment 13d: Iron Standards and Assessment Locations

Iron Standards:

March-April, Iron(chronic) = 3040(T), snowmelt season median values

May-February, Iron(chronic) = 1110(T), no-snowmelt season median values

Iron 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

(k) Yampa River Segment 13e: Iron Standards and Assessment Locations

Iron Standards:

Upper Sage Creek: Iron(chronic) = 1250(T), median of all data

Lower Sage Creek: Iron(chronic) = 1000(T), median of all data

Break between Upper and Lower Sage Creek is the west border of Section 18, T5N, R87W.

Iron Assessment Locations:

Yoast Stream Site 2 on Sage Creek (YSS2): located upstream of the west border of Section 18, T5N, R87W

Seneca II-W Stream Site 3 on Sage Creek (WSSF3): located downstream of the west border of Section 18, T5N, R87W

(l) Yampa River Segment 13f: Temperature Standards

DM = 21.2 and MWAT = 16.9 from 4/1 - 5/31

DM and MWAT = CS-II from 6/1 - 9/30

DM = 21.2 and MWAT = 16.9 from 10/1 - 10/31

DM and MWAT = CS-II from 11/1 - 3/31

(m) Yampa River Segment 22: Temperature Standards

All locations DM and MWAT = CL, CLL from 1/1 - 3/31

Pearl Lake DM = CLL and MWAT = 19.6 from 4/1 - 12/31

Steamboat Reservoir DM = CLL and MWAT = 21.6 from 4/1 - 12/31

Stagecoach Reservoir DM = CLL and MWAT = 21.7 from 4/1 - 12/31

All other locations DM and MWAT = CL,CLL from 4/1-12/31

(a) E. coli criteria and resulting standards for individual water segments, are established as indicators of the potential presence of pathogenic organisms. Standards for E. coli are expressed as a two-month geometric mean. Site-specific or seasonal standards are also two-month geometric means unless otherwise specified.

(b) All phosphorus standards are based upon the concentration of total phosphorus.

(c) The pH standards of 6.5 (or 5.0) and 9.0 are an instantaneous minimum and maximum, respectively to be applied as effluent limits. In determining instream attainment of water quality standards for pH, appropriate averaging periods may be applied, provided that beneficial uses will be fully protected.

(d) All mercury standards apply to the total recoverable fraction of all forms, both organic and inorganic, of mercury in water.

(e) All ammonia, nitrate, and nitrite standards are based upon the concentration reported as nitrogen.

(a) Yampa River Segment 7 (COUCYA07)

Discharger-Specific Variance, Town of Oak Creek (CO0041106): Adopted 12/14/2020.

Total Inorganic Nitrogen (TIN) (acute) = TVS:15 mg/L; Expiration date: 6/30/2026. Effluent concentrations shall not exceed the current condition.