Code of Colorado Regulations
1000 - Department of Public Health and Environment
1002 - Water Quality Control Commission (1002 Series)
5 CCR 1002-36 - REGULATION NO. 36 - CLASSIFICATIONS AND NUMERIC STANDARDS FOR RIO GRANDE BASIN
Section 5 CCR 1002-36.5 - BASIC STANDARDS

Current through Register Vol. 47, No. 17, September 10, 2024

(1) Temperature

All waters of the Rio Grande Basin 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 Table B and metal standards found at 31.16 Table III. The column in the tables headed "Water + Fish" are presumptively applied to all aquatic life class 1 streams which also have a water supply classification, and are applied to aquatic life class 2 streams which also have a water supply classification, on a case-by-case basis as shown in Appendix 36-1. The column in the tables at 31.11 and 31.16 Table III headed "Fish Ingestion" is presumptively applied to all aquatic life class 1 streams which do not have a water supply classification, and are applied to aquatic life class 2 streams which do not have a water supply classification, on a case-by-case basis as shown in Appendix 36-1.

(3) Uranium

(a) All waters of the Rio Grande 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 µg/L or naturally-occurring concentrations (as determined by the State of Colorado), whichever is greater.
(i) The first number in the 16.8-30 µg/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 December 31, 2022 for chlorophyll a and prior to December 31, 2027 for total phosphorus, interim nutrient values will be considered for adoption only in the limited circumstances defined at 31.17(e) and (f). These circumstances include headwaters, Direct Use Water Supply (DUWS) Lakes and Reservoirs, and other special circumstances determined by the Commission. Additionally, prior to December 31, 2027, only total phosphorus and chlorophyll a will be considered for adoption. After December 31, 2027, total nitrogen will be considered for adoption per the circumstances outlined in 31.17(g).

Prior to December 31, 2027, nutrient criteria will be adopted for headwaters on a segment by segment basis for the Rio Grande Basin. 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 Rio Grande Basin:

Segment

Permittee

Facility name

Permit No.

CORGRG02

Mountain Views at Rivers Edge RV

Mtn Views At Rvrs Edge Rv Rst

COG588069

CORGRG04b

South Fork Water and Sanitation District

South Fork Water and San Dist WWTF

COG588039

CORGRG04c

Monte Vista City of

Veterans Center WWTF

CO0036927

CORGRG04c ;CORGRG15

Monte Vista City of

Henderson Lagoon Facility

CO0023132

CORGRG04b ;CORGRG18

Del Norte Town of

Del Norte WWTF

CO0020281

CORGRG07

Creede City of

Creede WWTF

CO0040533

CORGRG09b

Fun Valley Resort

Fun Valley Resort

COG588018

CORGRG09a

Wolf Creek Ski Corp

Wolf Creek Ski Corp WWTF

CO0041785

CORGRG12

Alamosa City of

Alamosa Regional WWTF

CO0044458

CORGRG15

San Luis Water and Sanitation District

San Luis Water and San Dist WWTF

COG589082

CORGRG31

Costilla County Water and Sanitation System

Costilla County Water & San Dist WWTF

CO0036528

CORGAL12

La Jara Town of

La Jara WWTF

CO0020150

CORGAL15

Manassa Town of

Manassa WWTF

CO0042935

CORGAL18

Antonito Town of

Antonito WWTF

CO0040975

CORGCB06

Baca Grande Water and Sanitation District

Aspen Institute

CO0046914

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 note was added to the total phosphorus and chlorophyll a standards in these segments. The note references the table of qualified facilities at 36.5(4).

* For segments located entirely below these facilities, nutrient standards do not apply.

A note 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.

Disclaimer: These regulations may not be the most recent version. Colorado may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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