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mining activities. The loading facilities and office azea aze adjacent to Oak Creek, but are <br />above the 100-year, 24-hour floodplain. <br />Trout Creek forms the western boundary of the permit area. The ephemeral streams <br />which drain the peanit area flow west or northwest into Trout Creek. Sediment ponds are <br />located at the base of these tributaries above their confluence with Trout Creek. The <br />disturbed area is 3,400 acres, or approximately 10 percent of the 54 square mile Trout <br />Creek drainage basin. The average annual runoff in Trout Creek is 37,500 acre-feet. The <br />mine area is estimated to yield approximately 730 acre-feet of runoff annually, or about 2 <br />percent of the total annual stream flow of Trout Creek above the mine. Annual mean <br />minimum discharge is estimated at 10 cubic feet per second (cfs). <br />Only a small area of mine-related disturbance drains into Oak Creek. Although no <br />mining occurs within this watershed, the loadout, conveyor, access road, and office are <br />situated within the Oak Creek Basin. Of the total 140 acres of basin area within the <br />permit boundary, only about 24 acres are disturbed by the mine. This azea is a small <br />fraction of the total drainage area of 27.4 square miles upstream of the mine on Oak <br />Creek. Average annual yield is estimated at 7,900 acre-feet. Runoff from the permit area <br />is estimated at 25 ac-ft, or 0.3 percent of the total annual stream flow of Oak Creek above <br />the mine. The estimated mean minimum flow is 5 cfs. <br />Seasonal runoff hydrographs for both streams show peak discharge occurring in April, <br />May, and June as a result of snowmelt runoff. Low flows in both streams begin in the <br />late summer and extend through the winter months until the onset of spring runoff. <br />A large poRion of the pertnit azea has been previously mined, replacing consolidated <br />overburden with spoil materials. Deep percolation of precipitation through the spoils has <br />created a water table aquifer which abuts against the now buried highwall or box cut near <br />the foot of the previously mined slope. Numerous springs have formed as a result. These <br />springs emanate from the relatively steep slope which exists above the alluvium on the <br />east side of Trout Creek. <br />Water quality conditions upstream of the mine indicate that dissolved iron, manganese <br />and other trace metals all have occasionally exceeded receiving stream standards. <br />Baseline data indicate minor changes in water quality occur between upstream and <br />downstream stations on both Trout and Oak Creeks. This is probably due to the impacts <br />of past mining activities. The baseline quality of the water in Oak Creek is generally <br />poorer than that in Trout Creek above the permit area due to more extensive mining that <br />has occurred in the Oak Creek drainage during the past century. <br />Land Use <br />Current and historic land use in the vicinity of the operation has been coal mining, <br />livestock grazing and wildlife habitat. Historically, coal has been extracted from the mine <br />area by both surface strip and underground methods. <br />Edna Mine 7 Permit Renewal No. 4 <br />