2018-03-01_HYDROLOGY - C1981010 (2)

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COLORADO �~ Water Quality Assessment I; , `• ` Department of Public > '':._.1 Health b Environment Because segments COLCLY03a and COLCLY03b are classified for aquatic life warm 2 without a water supply designation, the aquatic life standards apply to this discharge. Segment COLCLY02 is classified for aquatic life warm 1 with a water supply designation; therefore, the water + fish standards apply to the discharge based on this segment. Salinity: Regulation 61.8(2)(1) contains requirements regarding salinity for any discharges to the Colorado River Watershed. For industrial dischargers and for the discharge of intercepted groundwater, this is a no - salt discharge requirement. However, the regulation states that this requirement may be waived where the salt load reaching the mainstem of the Colorado River is less than 1 ton per day, or less than 350 tons per year. The Division may permit the discharge of salt upon a satisfactory demonstration that it is not practicable to prevent the discharge of all salt. See Regulation 61.8(2)(l)(i)(A)(1) for industrial discharges and 61.8(2)(l)(iii) for discharges of intercepted groundwater for more information regarding this demonstration. In addition, the Division's policy, Implementing Narrative Standards in Discharge Permits for the Protection of Irrigated Crops, may be applied to discharges where an agricultural water intake exists downstream of a discharge point. Limitations for electrical conductivity and sodium absorption ratio may be applied in accordance with this policy. Nutrients Phosphorus and Total Inorganic Nitrogen: Regulation 85, the Nutrients Management Control Regulation has been adopted by the Water Quality Control Commission and became effective September 30, 2012. This regulation contains requirements for phosphorus and Total Inorganic Nitrogen (TIN) concentrations for some point source dischargers. Limitations for phosphorus and TIN may be applied in accordance with this regulation. Temperature 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. Segment Specific Numeric Standards Numeric standards are developed on a basin -specific basis and are adopted for particular stream segments by the Water Quality Control Commission. The standards in Table A -4a, Table A -4b and Table A -4c have been assigned to stream segments COLCLY03a, COLCLY03b and COLCLY02, respectively, in accordance with the Classifications and Numeric Standards for Lower Colorado River Basin. Table A -4a In -stream Standards for Stream Segment COLCLY03a Deacon Gulch (Outfall 025) Physical and Biological Dissolved Oxygen (DO) = 5 mg/l, minimum pH 6.5- 9.0 E. coli chronic = 630 colonies/100 ml Temperature March -Nov = 28.7° C MWAT and 31.8° C DM Temperature Dec -Feb = 14.3° C MWAT and 24.9° C DM Inorganic Free Cyanide acute = 0.2 mg/1 PagQe 10 of 40 4300 Cherry Creek Drive 5., Denver, CO 80246-1530 p 303-692-2000 www.colorado.gov/cdphe/wgcd I ��