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<br />816.41 <br />HYDROLOGIC BALA:4CE: GE:~'cFAL ?.rQUI?.E'.T-ti1T5 <br />SURFACE [dATER (v2,on.316-21 to 816-24) <br />A. Descrip*_ion of Existing Environment <br />Foidel Creek drains the area of Energy Mine [vo. 1 <br />in the Eckman Pari: area, runoff in affected areas <br />`lows into the south forl: of Foidel Creek (unnamed <br />on hydrology maps). Foidel Creek is an intermittent <br />stream. Downstream of EFC. Foidel Creek averages <br />1.23 cfs with a peak: flow of 16.5 cfs. The number <br />of flow days per year averages 120 days. <br />Runoff in the Energy .sine [Jo. 2 area drains to <br />Fish Creek, a perennial stream with a low base- <br />flow, 3 cfs, frost ground water. 1`[ost of its <br />significant flows are the result o` =:ownelt. <br />Strearl'_ioc: data for four years, collected by t'.:e <br />USGS, at their newly installed Foidel Creek gauging <br />station (Table II). <br />Average annual precipitation is 14 to 16 inches. <br />The 10-year, 24-hour precipitation event is 1.8 <br />inches, The 100-year, 24-hour precipitation event is <br />2.7 inches. <br />Baseline surface taater quality in the mine area is of <br />the calcium bicarbonate type, and is alkaline, <br />moderately saline and high in suspended load. This <br />data is summarized in Table 15. High concentrations <br />of suspended sediment and suspended chemical constitu- <br />ents are carried in high flow runoff. Very little solids <br />are contributed by low flows. Dissolved salts are <br />diluted by large volumes and tend to be lower in high <br />flow event. The pY. values vary between 8.8 and 7.7 <br />for baseline conditions. Dissolved soilds,suspended <br />solids and calcium carbonate are the main characteris- <br />tics affected by the Wining operation. <br />As a result of mining there will be an increase in the <br />sa1C load to the Colorado River. This increased <br />salt load will result from leaching of sulfate salts <br />from the spoil and into the Twenty Mile Park ground <br />water basin. According to ~ or <br />mo ribe a ove in the se ater <br />quality, it wil ta.e a ately 50 yrs befQr.e_any <br />o the sa t oa wi dischar e u zce_through <br />s r h. ain, based on the solute <br />transpo mo el, the salt load will be extremely <br />dilute and the affect of total salt load -rr- a on <br />the Colorado River will be extremely small. <br />