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t <br />°f COLORADO <br />Department of Public <br />rB�I Health b Environment <br />Water Quality Assessment <br />Parameter <br />Number <br />of <br />Samples <br />15th <br />Percentile <br />50th <br />Percentile <br />85th <br />Percentile <br />Mean <br />Maximu <br />m <br />Chronic <br />Stream <br />Standard <br />Notes <br />As, Dis (pg/1) <br />3 <br />0 <br />0 <br />0.38 <br />0.18 <br />0.54 <br />340 <br />1 <br />Cd, Dis (pg/1) <br />24 <br />0 <br />0 <br />0 <br />0.00075 <br />0.018 <br />0.50 <br />1 <br />Cr, Dis (pg/1) <br />4 <br />0 <br />0 <br />0 <br />0 <br />0 <br />NA <br />1 <br />Cu, Dis (pg/l) <br />24 <br />0 <br />0 <br />0.89 <br />0.95 <br />15 <br />11 <br />1 <br />Fe, Dis (pg/l) <br />5 <br />58 <br />75 <br />105 <br />80 <br />120 <br />300 <br />Fe, TR (pg/1) <br />5 <br />336 <br />600 <br />1840 <br />1020 <br />2500 <br />1000 <br />Pb, Dis (pg/1) <br />24 <br />0 <br />0 <br />0.0083 <br />0.005 <br />0.04 <br />3.20 <br />1 <br />Hg, Tot (pg/1) <br />0 <br />- <br />0.01 <br />2 <br />Mn, Dis (pg/1) <br />5 <br />11 <br />15 <br />50 <br />27 <br />54 <br />50 <br />Ni, Dis (pg/t) <br />4 <br />0 <br />1 <br />2.4 <br />1.2 <br />2.7 <br />62 <br />1 <br />Se, Dis (pg/l) <br />24 <br />0.049 <br />0.2 <br />0.77 <br />0.44 <br />2.7 <br />4.6 <br />Ag, Dis (pg/t) <br />24 <br />0 <br />0 <br />0 <br />0 <br />0 <br />0.46 <br />1 <br />Zn, Dis (pg/l) <br />24 <br />0 <br />0 <br />2.1 <br />1.1 <br />11 <br />147 <br />1 <br />Sulfate (mg/l) <br />5 <br />12 <br />52 <br />100 <br />58 <br />150 <br />250 <br />Hardness as <br />CaCO3 (mg/l) <br />50 <br />83 <br />123 <br />162 <br />124 <br />303 <br />NA <br />Note 1: When sample results were below detection levels, the value of zero was used in accordance with the <br />Division's standard approach for summarization and averaging purposes. <br />Note 2: Upstream data for total mercury were not available. <br />Facility Information <br />The Trapper Mine is located approximately 6.5 miles southwest of Craig on County Road 1075 in Moffat <br />County. Wastewater treatment is accomplished using sedimentation ponds. The maximum 30 -day average <br />varies by outfall and is included in Table A-1. The technical analyses that follow include assessments of the <br />assimilative capacity based on the design capacity. <br />An assessment of Division records indicate that there are 17 facilities discharging to the same stream <br />segments, but are discharging to different streams. These facilities are all covered under general permits. <br />Due to the in -stream low flow of zero, the assimilative capacities during times of low flow are not affected <br />by nearby contributions. Therefore, modeling nearby facilities in conjunction with this facility was not <br />necessary. <br />Pollutants of Concern <br />Pollutants of concern may be determined by one or more of the following: facility type; effluent <br />characteristics and chemistry; effluent water quality data; receiving water quality; presence of federal <br />effluent limitation guidelines; or other information. Parameters evaluated in this WQA may or may not <br />appear in a permit with limitations or monitoring requirements, subject to other determinations such as a <br />reasonable potential analysis, mixing zone analyses, 303(d) listings, threatened and endangered species <br />listings or other requirement as discussed in a permit rationale. <br />There are no site-specific in -stream water quality standards for TSS and oil and grease for this receiving <br />stream. Thus, assimilative capacities were not determined for these parameters. The applicable <br />limitations for these pollutants can be found in Regulation No. 62 and will be applied in the permit for the <br />WWTF. <br />Paee 19 of 40 <br />4300 Cherry Creek Drive S., Denver, CO 80246-1530 303-692-2000 www.colorado.gov/cdphe/wqcd I <br />