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<br />C. Surface Water <br /> <br />The surface water general area included in the CHIS consists of all surface <br />drainage in the Upper Yampa River Subbasin above Hayden (Figure No. 2). The <br />long-term estimated average annual flow from the subbasin is about 1.1 million <br />acre-feet (Steele, et al, 1979). Approximately 65 percent of this annual flow <br />occurs during snow melt runoff in May and June (Steele, et al, 1979). Water <br />resources development within the Upper Yampa River Subbasin relies primarily <br />on surface water supplies. The majority of municipal, industrial, domestic, <br />stock and irrigation water supplies in the area are from surface water. <br />Water quality (in terms of TDS concentration) in the Upper Yampa River <br />Subbasin is variable and is related to both the geology of the source areas <br />and climatic conditions. Surface waters draining high-altitude snow pack <br />areas are generally lower in dissolved solids due to the low soluble salt <br />content of the igneous and metamorphic rack types in these areas. Surface <br />waters draining from the sedimentary rock basins associated with the coal <br />deposits may yield higher TDS concentration due to the greater amounts of <br />soluble salts in these rock types. Also, surface water quality in streams <br />draining the area varies on a seasonal basis. TDS concentration is lowest <br />during snow melt runoff periods and highest during lower flow periods in late <br />summer through winter. <br />The primary drainages in the Upper Yampa River Subbasin related to coal mining <br />activities include both small tributaries and major tributaries. The major <br />tributaries of interest are Trout Creek, Fish Creek, Oak Creek, and <br />Sage Creek. These streams generally exhibit perennial flow except Sage <br />Creek. The small tributaries are Foidel Creek, Middle Creek, Grassy Creek, <br />and Dry Creek. These streams flow intermittently in response to snow melt and <br />rainfall events and exhibit limited base flow (ground water component of flow). <br />The Seneca II-W Mine permit boundary lies within both the Sage Creek and <br />Dry Creek watersheds, however, ail disturbed area drainage is directed to <br />Dry Creek. Dry Creek flaws north-northeast to the Yampa River near Hayden, <br />Colorado. Hubberson Gulch and an unnamed tributary to Hubberson Gulch will <br />receive all disturbed area drainage from the south mine area, this will be the <br />area evaluated for the following CHIS and PHC portions of this document. <br />Hubberson Gulch is gaged at U.S. Geological Survey Station 09244464 as it <br />exits the permit area downstream of its confl uence with the above referenced <br />unnamed tributary. The data submitted with the permit application from July, <br />1979 through September, 1981, indicated that the stream is intermittent with <br />periods of zero flow in late summer-early fall. Baseflow is 0.1 cfs with a <br />maximum peak flow from snow melt observed at 30 cfs. The snow melt generally <br />peaks in mid-April and recedes to baseflow by July. Average flow for the 1980 <br />water year was 1.1 cfs. <br />Hubberson Gulch water is a calcium-magnesium sulfate type, slightly alkaline, <br />high in salinity and very hard. The pH ranges between 7.1 and 8.9 Total <br />dissolved solids range from 385 to 1632.2 mg/7. TDS concentration generally <br />shows an inverse relation to streamflow. Total suspended solids (TSS) range <br />from 5 to 606 mg/1. TSS concentration is highest during high flow periods of <br />snow melt runoff and after intense precipitation events. <br />-30- <br />