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EXHIBIT B • <br />Calculation Sheet <br />Effects of Mine Discharges on Middle Creek Water Quality in the <br />Foidel, Middle and Trout Creek Confluence Area <br />Methodology: <br />Determine the amount of land to be irrigated. Determine the minimum <br />amount of water required to irrigate the land. Add the mine discharges <br />to this minimum amount and perform amass balance calculation. Use the <br />period of June to August as the critical irrigation period. <br />Mean dissolved solids during low flow year: (Site 29) <br />06/23/81 692 mg/L <br />06/14/81 564 mg/L <br />08/19/81 724 mg/L <br />Mean 660 mg/L <br />olids <br />Maximum dissol <br />ed durin (Site 29) <br />i <br />ri <br />tion season <br />v <br />s g ga <br />: <br />r <br />06/05/80 400 mg/L <br />06/10/80 492 mg/L <br />06/17/80 500 mg/L <br />06/23/80 1530 mg/L <br />06/30/80 1690 mg/L <br />07/07/80 1970 mg/L <br />07/15/80 1950 mg/L <br />07/22/80 1270 mq/L <br />07/28/80 720 mg/L <br />08/04/80 2500 mg/L <br />08/11/80 3060 mg/L (maximum) <br />08/25/80 2890 mg/L <br />Mean 1808 mg/L <br />Potentially irrigated acreage: 20 acres <br />Water requirement per acre: 1 foot per month during June to August (CYCC <br />Little Middle Creek Tract Permit No. C-81-071 (revision) May, 1986, Exhibit <br />26, p. 26-11) <br />Minimum natural flow requirement: <br />20 acres x 1 foot = 20 acre feet per month =_> 0.33 cfs <br />• <br />28 Revised 10/1/86 <br />