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<br /> <br />steep slopes were approximately restored. <br />Assuming successful reclamation of disturbed areas, <br />postmining runoff should not be significantly dif- <br />ferent from premining conditions, either in volume or <br />peak discharge. Because of the steep slopes, however, <br />annual runoff could be increased several fold if <br />reclamation were less successful than expected. <br />Dissolved solids concentration in runoff from the <br />respective watersheds would probably not increase <br />significantly as a result of mining. Sodium and <br />sulfate content is expected to increase, however, <br />with a corresponding decrease in calcium, magnesium, <br />and bicarbonate. This change in water chemistry <br />should have no significant impact on use of the water <br />downstream. <br />c. Erosion and Sedimentation <br />Regulations pursuant to the Surface Mining Reclamation <br />and Enforcement Act (30 CFR 715.17(a)) limit the total <br />suspended solids in runoff from areas disturbed by <br />surface mining to 45 mg/1 maximum allowable except <br />for discharge from a precipitation event larger than <br />10-year 24-hour recurrence interval. The average of <br />daily values for 30 consecutive discharge days cannot <br />exceed 30 mg/1. <br />126 <br />