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Cotter Corporation Water Quality Assessment CO0036251 <br />Salinity and Phosphorus <br />Phosphorus: Regulations 71, 72, 73 and 74, for Dillon Reservoir Watershed, Cherry Creek Reservoir <br />Watershed, Chatfield Reservoir Watershed and the Bear Creek Watershed, contain requirements for <br />phosphorus concentrations and phosphorus annual loadings for point source dischargers. If a facility <br />discharges to one of these watersheds, a phosphorus allocation may be necessary, and limitations and <br />annual loadings may be added to a permit. <br />Salinity: Regulation 61.8(2)(1) contains requirements regarding salinity for any discharges to the <br />Colorado River Watershed. For industrial dischargers this is a no -salt discharge requirement. However, <br />the regulation states that this requirement may be waived where the salt load reaching the mainstem of <br />the Colorado River is less than 1 ton per day, or less than 366 tons per year. The Division may permit <br />the discharge of salt upon a satisfactory demonstration that it is not practicable to prevent the discharge <br />of all salt. See Regulation 61.8(2)(1)(i)(A)(1) for more information regarding this demonstration. <br />For municipal dischargers, an incremental increase of 400 mg/1 above the flow weighted averaged <br />salinity of the intake water supply is allowed. This may be waived where the salt load reaching the <br />mainstem of the Colorado River is less than 1 ton per day, or less than 366 tons per year. The Division <br />may permit the discharge of salt in excess of the 400 mg /1 incremental increase, upon a satisfactory <br />demonstration that it is not practicable to attain this limit. See Regulation 61.8(2)(1)(vi)(A)(1) for more <br />information regarding this demonstration. <br />Regulation 75 contains requirements for the release of water from Cheraw Lake. Any entity releasing <br />water from Cheraw Lake must ensure that either: 1) the water has a TDS concentration less than or equal <br />to 4300 mg/1, or 2) that an adequate quantity of water of less saline nature can be supplied for dilution <br />purposes such that a salinity level of 4300 ppm, measured as TDS, can be maintained in Horse Creek <br />immediately above the first diversion below the confluence with the Cheraw Lake outlet channel. <br />In addition, the Division's policy, Implementing Narrative Standards in Discharge Permits for the <br />Protection of Irrigated Crops, may be applied to discharges where an agricultural water intake exists <br />downstream of a discharge point. Limitations for electrical conductivity, sodium absorption ratio, or <br />sodium, may be applied in accordance with this policy. <br />Segment Specific Numeric Standards <br />Numeric standards are developed on a basin - specific basis and are adopted for particular stream <br />segments by the Water Quality Control Commission. To simplify the listing of the segment- specific <br />standards, many of the aquatic life standards are contained in a table at the beginning of each chapter of <br />the regulations. The standards in Table A -3a have been assigned to stream segment COGULD03a, while <br />the standards in Table A -3b have been assigned to stream segment COGULD02 in accordance with the <br />Classifications and Numeric Standards for Gunnison and Lower Dolores River Basins. <br />Appendix A (wQA v 7.0) Page 7 of 23 Last Revised 06/10/10 /AO <br />