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The Bowie No. 1 Mine has not projected any mine inflow discharges. Inflows into the mine have averaged 3 to 5 gpm. The <br />maximum mine discharge from the Bowie No. 1 Mine was estimated at 100 gpm for this analysis, with a salinity of 2,500 mg/I. <br />~~~ The Bowie No. 2 Mine is not expected to discharge significant quantities of underground mine water; however, [his analysis will <br />project a discharge of 175 gpm with an average salinity of 2900 mg/I [o ensure a conducted analysis. These numbers are presented <br />and substantiated with the Bowie No. 2 Mine permit application. <br />All of the mine discharges will enter the North Fork of [he Gunnison River. The impact to the river was assessed by determining the <br />increase in the total dissolved solids concentration in the river using a standard mixing equation. The downstream concentration (Ca) <br />is determined by: <br />CJ - <br />CuQn + t-'iQi + CzQz + C3Q~ + ... CnQn <br />Qu +`ll +Q2+`G3 +... Qn <br />Where Cn is the upstream TDS concentration (mg/1), Q~ is the upstream discharge (CFS), C,...Cn aze the respective TDS concentrations <br />of the mines contributing water to the river (mg/1) and Qt...Qn are the respective discharges to the river (CFS). Data for the mines <br />in the area used in the equation are presented in Table 3. The upstream TDS concentration (C„) of the North Fork of the Gunnison <br />River was assumed to be 95 mg/1. <br />Table 3: Mine Discharge and Effluent Concentration <br /> Discharge TDS Salt Load <br />Mine Name (CFS) (me/I) Tons/Year <br />Bear 0 NA . 0 <br />..: Blue Ribbon 0 NA 0 <br />Hawk's Nest 0.446 3000 1318 <br />West Elk 2.230 2500 5670 <br />Bowie No. 1 0.223. 2500 567 <br />Somerset 1.471 .3200 4641 . <br />Terror Creek 0 NA 0 <br />Bowie No. 2 0.391 2800, 1076 <br />Totals 4.761 15124 <br />The impact on the river was assessed at four different flows, aten-year, seven day low flow (Qr,,o) of 32.5 CFS, the average minimum <br />daily flow (1968-78) of 47.6 CFS, the average minimum monthly flow (1968-78) of 66 CFS and the average flow for the period of <br />record (45.2 years) of 432 CFS. The downstream flow and TDS concentration was calculated for each flow (Table 4). <br />. 14 <br />