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entirely depleted in July so that August is begun with no water in storage and the <br />actual evapotranspiration is limited To the August infiltration. Continuing the <br />cornputotions to November verifies the assumption that water available in storage at <br />the beginning of that month is zero. <br />~'fS~arice - It is estimated that the average annual <br />precipitation on The Edna Mine is winches. Approxirnotely-!a~:i9 inches of water <br />are lost to evaporation and sublimation during the winter months. Of the remaining <br />16.83 inches, evapotranspiration accounts for k4w~inches, overland runoff for <br />another Os and the remainin~ Thus, it is <br />estimated That the combined surface and subsurface runoff 2.1 t~inches or%Iw~ <br />percent of the annual precipitation. Of the total runoff, 7 percent occurs as surface <br />flow and t as subsurface flow. These runoff estimates appears very <br />reasonable in di t of measured combined runoff from portions of the permit area. <br />McWho~er, al., (1979) report the mean drainage from the Central and West <br />Ridge portions of the it area to be 4 inches in 1975. This figure includes both <br />surface and subsurface r nd was measured during a year in wh1~ <br />91agppr~nl~d. These in ti ators also estimate that, over Their study period, <br />subsurface runoff accounted f~ 96 rcenT of the total. The measured total runoff <br />and the partitioning of the total into surface and subsurface components, although <br />not determined for on average year, tend to verify the reasonableness of the <br />hydrologic balance presented herein. <br />The permit area is 4,330 acres, approximately. About ~9,~ acres of The <br />permit area are in The Trout Creek watershed and the remainini~,140 acre?are in the <br />Oak Creek drainage. Basedese areas and a mean annu run of 2.10 inches, <br />' .,.. <br />the permit area contribute 0 ac-~f'Salo Trout Creek a. 25 ac-ft. to` C36tP' 'ree c~. <br />A mean annual runoff of 37,500 ac-f t. was estimated for T e'~'brt~ion o{ the Trout <br />Creek watershed above the downstream gaging station TR-,;~,~,$s..,the runoff from <br />.~., <br />the permit area is expected To contribute approximatel¢,* percent ~f the mean <br />annual flow in Trout Creek where iT leaves the mine area. ~~~^ `"'",,,~ <br />The estimate of 0.45 feet of runoff on the Oak Creek watershed converts to <br />a mean annual volume of 7,900 ac-f T. of OK-a near the office complex. The <br />contribution To this mean annual flow from the portion of The permit area in the Oak <br />Creek watershed is expected to be on The order 0. perc <br />J <br />2.5-88 <br />