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Twentymile Coal Company Water Quality Assessment 000042161 <br />Road 27 downstream to the confluence with Trout Creek." This segment is classified for class 1 <br />cold water aquatic life, class 1 recreation and agriculture. Numeric standards are developed on a <br />basin-specific basis and are adopted for particular stream segments by the Water Quality Control <br />Commission. To simplify the listing of the segment-specific standards contained in the regulations, <br />many of the aquatic life standards are specified as Table Value Standards (TVS). <br />The standards in Table A-2 have been assigned to Segment 136 of the Yampa River Basin, <br />COUCYAI3B, in accordance with CDPHE's Classification and Numeric Standards jor the Upper <br />Colorado River Basin and North Platte River (Planning Region 12) Regulation 33. <br />n <br />L.J <br />Table A-2 <br />In-stream Standards for the Yampa River Basin, Stream Segment 13b <br />~~ <br />t : ogtc <br />Dissolved Oxygen (DO) = 6.0 mg/1 <br />Dissolved Oxygen (DO) spawning = 7.0 mg/1 <br />pH = 6.5-9.0 su <br />Fecal Colifotm = 200 colonies/100 mis <br />0 <br />Un-ionized ammonia (NH,) acute =TVS <br />Un-ionized ammonia (NH,) chronic = 0.02 mg/1 <br />Chlorine (CI,) acute =0.019 mg/1 <br />Chlorine (Cl2) chronic = 0.011 mg/I <br />Free Cyanide = 0.005 mg/1 <br />Sulfide = 0.002 mg/I <br />Boron = 0.75 mg/] <br />Nitrite (NOZ) = 0.05 mg/I <br />Total Recoverable Arsenic acute = 100 ug/1 <br />Dissolved Cadmium acute for trout and chronic =TVS <br />Dissolved Trivalent Chromium acute and chronic =TVS <br />Dissolved Hexavalent Chromium acute and chronic =TVS <br />Dissolved Copper acute and chronic =TVS <br />Total Recoverable Iron chronic = 1000 ug/I <br />Dissolved Lead acute and chronic =TVS <br />Dissolved Manganese acute and chronic =TVS <br />Total Mercury chronic = 0.01 ug/1 <br />Dissolved Nickel acute and chronic =TVS <br />Dissolved Selenium acute and chronic =TVS <br />Dissolved Silver acute and chronic for trout =TVS <br />Dissolved Zinc acute and chronic =TVS <br />Many of the TV S standards are based on the hardness of the receiving stream and/or the species of <br />• fish in the receiving stream. Thus, the in-stream standards based on the TVS must be calculated <br />A Page 3 of 12 <br />