2009-03-06_PERMIT FILE - C1981012A (6)

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CO-0000906 New Elk Mine Water Quality Assessment the New es had Elk Mine O nt all The ratio of the low flow of the Middle Fork of the Purgatoire River to • 001 design flow is 0.77:1. The nearest upstream and downstream lit the are relat'? ely lirmited, to the small assimilative capacities available to the New Elk Mine Outfa available dilution, analyses indicate that assimilative cap c te the Left Fork of Apache Canyon Creek has a low According to available and historical information, Howevon BM flow of zero. The New Elk Mine Outfall 009 as well as disch ogees a he Canyon h Creeke Project (COG-900007) are known point source contributors p despite nearby contributions, the findings of this assessment indicate that there is no dilution in the Left Fork of Apache Canyon Creek and therefore assimilative ffluent discharge. are equal to the in-stream standards applied to the New Elk Mine Outfall 009 e the Division, Information used in this assessment includes data gathered from the New Elk Mine, Riverwatch, the U. S. Environmental Protection Agency (EPA), the consist olf gthe ic best iey (USG), and the U.S. Census Bureau. The data used in the assessment available at the time of preparation of this WQA analysis. II. Water Quality The New Elk Mine Outfall 001 discharges to the Water Body Identification (WBID) stream ssgmeennt River basin trea CO?,RLAOSa, which means the Arkansas River B esin,e t as liedainsTable A Sub-was found in the • Segment 05a. The composition description of this s gm regulations at the time of preparation of this WQA• However, oere rRiverIwlas originally proposed to fall description is incorrect, as the Middle Fork of the Pu g under this segment but translation errors were made from the final regulations during transposition by the Water Quality Control Commission. Because corrections to the segment description are intended to be finalized prior to the issuance of this permit, this WQA is being prepared based on the soon to be corrected segment description, which falling AquaticrL fe Class It COARLA05a. Stream segment COARLA05a is Class E Exisiting Primary Contact Use, Water Supply and Agriculture. The New Elk Mine Outfall 009 discharges to the Water Body Identification (WBID) stream ssgmeennt COARLA06, which means the Arkansas River Basin, Lower Arkansas River Sub-basin, Segment 06. This segment is composed of "All tributaries to the Purgatoire River, including all wetlands, lakes and reservoirs, from the source to Interstate 25, except for specific listings in segments 4, 5a and 5b." Stream segment COARLA06 is classified for Cold Water Aquatic Life Class 2, Class E Exisiting Primary Contact Use and Agriculture. Basic Standards have been developed in Section 31.11(2) and (3) of The Basic Standards and Methodologies for Surface Water to protect the waters of the state from radionuclides and organic chemicals. In Section 31.11(1) of the regulations, narrative standards are applied to any pollutant of concern, even where there is no numeric standard for that pollutant. Waters of the state shall be "free from harmful substances in harmful amounts." Total dissolved solids (TDS), and sediment are such pollutants of concern being discussed by Agricultural and Water Quality Standards • workgroups. In order to protect the Basic Standards in waters of the state, effluent limitations with Appendix A (wQn version s-acFASL» Page 3 of 29 Last Revised August 26, 2008