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Mountain Coal and Bear Coal Water Quality Assessment CO-0038776 and CO-0044377 station were available for a period of record from April 2001 through September 2002. No fecal coliforTn data were available from any upstream station and therefore a comparable watershed was used. Specifically, fecal coliform data for the USGS station 09124500 (Lake Fork of the Gunnison River at Gateview, CO) were available for the period ofrecord from December 1990 through August 1993 and were determined to be representative of the fecal coliform water quality upstream of the Mountain Coal and Bear Coal W WTFs. Data from these sources were combined and used to reflect upstream water quality. These data are summarized in Table A-6. Table A-6 Ambient Water Quali for the North Fork of the Gunnison River Ntinlier - '_ r t'hroxiae ,. of i5th SOfR ; , SSllt ,:.,° ~ Stream Parameter :Samples Percentile° Percentile Percentzle t•tUlean Standard~~ Nodes Te °C 50 1.2 8.6 14 8.2 20 H su) 9 8.1 8.3 8.4 8.1 6.5-9 Fecal Coliform (#/100 ml 12 _ _ _ 1 3 18 4 200 1 Hazdness (mg/1 CaC03) 3 43 53 60 52 NA Al, Dis u ) 3 15 50 64 40 NA As, Tot (u ) 3 0 0 0 0 NA 2 Cd, Dis u ) 3 ND ND ND ND 1.4 3 Cr, Tot u Q 16 0 4,0 10 ! 6.1 NA Cr Dis u '9 0 0 8.0 3.3: NA Cu, Dis u ) 3 ND ND ND ND 5.1 3 Fe, Tot u 4 211 280 707 443 NA Fe, Dis u ) 4 29 45 72 50 300 Pb, Tot (u /1) 3 0.12 0.40 0.54 0.33 NA Mn, Tot u 1) 3 14 21 22 18 NA Mn, Dis (u 3 0 0 4.2 2.0 50 2 H , Tot u ) 3 ND ND ND ND 0.010 3 Se, Dis u 4 0 0 0 0 4.6 2 Zn, Dis u 3 0 0 0 0 68 2 NHs, Tot (mg/1) 45 0 0.030 _.0.12 0.065 NA 2 TSS 4 0 4.0 IS 7.0 NA 2 Note 1: The calculated mean is the geometric mean. Note that for summarization purposes, the value of one was used where these was detectable amount because the geometric mean cannot be calculated using zero. Note 2: Whw sample results were below detection levels, the value of zero was used is accordance with the CO WQCD's standard approach fo ~~r„~*r ~,;zation and averaging pur)oses. Note 3: For the noted parameters, data were found a[ lest than detection levels. The detection levek, however, were greater than the in-stream standards. 1n accordance with WQCD standard procedures, no deteradnation of water quality is made when detection IeveLs are greater than in- stream standards. _Sylvester Gulch, West Sylvester Gulch, the Dry Fork of Minnesota Creek, and Lone Pine Gulch: The ambient water quality was not assessed for Sylvester Gulch, West Sylvester Gulch, the Dry Fork of Minnesota Creek and Lone Pine Gulch because the background in-stream low flow condition is zero upstream of the Mountain Coal WWTFs' dischazges. Appendix A Page 9 of 20 Last Revised 3/9/2004