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Mountain Coal and Bear Coal Water Quality Assessment CO-0038776 and CO-0044377 <br />station were available for a period of record from April 2001 through September 2002. No fecal <br />coliform data were available from any upstream station and therefore a compazable watershed was <br />used. Specifically, fecal coliform data for the USGS station 09124500 (Lake Fork of the Gunnison <br />River at Gateview, CO) were available for the period ofrecord from December 1990 through August <br />1993 and were determined to be representative of the fecal colifolm water quality upstream of the <br />Mountain Coal and Beaz Coal W WTFs. Data from these sources were combined and used to reflect <br />upstream water quality. These data are summarized in Table A-6. <br />Table A-6 <br />Ambient Water Quali for the North Fork of the Gunnison River <br />: <br /> <br />Parameter . :Number <br />of <br />Samples <br />15th <br />Percentile <br />50th <br />Percentile <br />85th <br />Percentile. <br /> <br />Mean Chronic. <br />Stream <br />Standard: <br /> <br />Notes <br />Tem °C ~0 1.2 8.6 14 8.2 20 <br />H (su) 9 8.1 8.3 8.4 8.1 6.5-9 <br />Fecal Coliform (#(100 <br />rnl) <br />12 <br />1 <br />3 <br />18 <br />4 <br />200 <br />1 <br />Hardness (mg/I CaC03) <br />3 <br />43 <br />53 <br />60 <br />52 <br />NA <br />AI, Dis (u /1 3 15 50 64 40 NA <br />As, Tot u 1) 3 0 0 0 0 NA 2, <br />Cd, Dis (u !1) 3 ND ND ND ND 1.4 3 <br />Cr, Tot u /Il 16 0 4.0 10 ~. 6.1 NA <br />Cr -Dis u /1 ~ 9 0 0 8.0 ~ 3.3 NA <br />Cu, Dis u 1 3 ND ND ND ND 5.1 3 <br />~Fe Tot (u°/1) 4 211 ~ 280 707 443 ~ NA <br />Fe, Dis (u /1) 4 29 45 72 50 300 <br />Pb, Tot (u ll) 3 0.12 0.40 O.SA 0.33 NA <br />Mn,Tot(u /]) 3 14 21 22 IS NA <br />Mn, Dis (u 1) 3 0 0 4.2 2.0 50 2 <br />He, Tot (u A 3 ND ND ND ND 0.010 3 <br />Se, Dis (u I) 4 0 0 0 0 4.6 2 <br />Zn, Dis (u /1 3 0 0 0 0 68 2 <br />NHs, Tot (mg11) 45 0 0.030 0.12 0.065 NA 2 <br />TSS tm 1) 4 0 4.0 IS 7A NA 2 <br />Note I: The calculated mean is [he geometric mean. Note [ha[ for surmnariza[ion purposes, the value of one was used where there was n <br />detectable amount because the geometric mean cannot be calculated using zero. <br />Note 2: When sample results were below detection levels, the value of zero was used in accordance with the CO WQCD's standard approach fo <br />surrnnarizationatrd averagin putposes. <br />Note 3: Far the noted patatneters, data were found at less than detection levels. The detection levels, however, were Beater than [he in-stream <br />standards. in accordance with WQCD standard procedures, no determination of water quality is made when detection IeveLs are Beater than in- <br />stream standards. <br />Sylvester Gulch, West Sylvester Gulch, the Dry Fork of Minnesota Creek, and Lone Pine <br />Gulch: The ambient water qualitywas not assessed for Sylvester Gulch, West Sylvester Gulch, the <br />Dry Fork of Minnesota Creek and Lone Pine Gulch because the background in-stream low flow <br />condition is zero upstream of the Mountain Coal WWTFs' dischazges. <br />Appendix .4 Page 9 of 20 Last Revised 319/2004 <br />