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<br />• 7.3.2 Surface Water Quality <br />Piceance Creek Watershed <br />Surface water in the Piceance Creek drainage basin is classified as mixed bicarbonate <br />in the upper portions of the drainage basin and sodium bicarbonate in the lower <br />portions. In general, the water quality in this drainage basin is poor and tends to <br />deteriorate downstream. <br />Chemical components found in Piceance Creek surface waters are attributed to the <br />weathering of surficial materials in the area. The principal ionic constituents in <br />Piceance Creek include sodium, calcium, magnesium, bicarbonate, sulfate, chloride, <br />potassium, and fluoride. Sodium, bicarbonate, and sulfate levels generally decrease <br />during the spring snowmelt runoff simply because of the increased amount of <br />water, while chloride and fluoride remain essentially constant. Calcium and <br />magnesium concentrations show small decreases, and potassium increases during <br />the snowmelt. During the irrigation season (July), sodium becomes concentrated, <br />and calcium and magnesium concentrations increase. <br />In late summer and fall, Piceance Creek flow is controlled primarily by groundwater <br />discharge, which causes the water to be high in dissolved solids and to have <br />decreased sediment loads. Concentrations of dissolved solids in the surface water <br />• may range from that found in rainwater and snowmelt in the upper elevations of <br />the basin to over 2,120 milligrams per liter (mg/1) in Piceance Creek at its confluence <br />with the White River. Total dissolved solids (TDS) in Piceance Creek below Ryan <br />Gulch ranged from 588 to 1,450 mg/l between October 1978 and September 1979. The <br />TDS concentration of Piceance Creek water entering the White River ranged from <br />720 to 2,120 mg/1 during the same period (USGS 1981). Surface water quality and <br />recharge systems are described in the BLM's Final Environmental Assessment No. <br />CO-117-82-55 for Sodium Preference Lease Applications C-0018328, C-0018329, and C- <br />0120057 (BLM Sodium Leases FEA) (BLM 1982). <br />Parachute Creek Watershed <br />In general, the water quality in the Parachute Creek drainage basin is typical of <br />surface waters from semi-arid areas of western Colorado. The water is slightly <br />alkaline, with mean pH values ranging from 8.0 to 8.5 (ACOE 1985). The major <br />anion in these waters is bicarbonate, with some carbonate present when the pH <br />exceeds 8.3 (ACOE 1985). The concentrations of trace metals in the waters are <br />generally low and are well below established water quality standards (ACOE 1985). <br />Concentrations of chemical constituents are generally lowest in the upstream <br />reaches of the Parachute Creek drainage. Farther down the Parachute Creek <br />drainage, soluble sa]ts accumulate from natural runoff and irrigation return flows <br />• (ACOE 1985). <br />American Soda, L.L.P. 7_16 <br />Commercial Mine Plan <br />August 18, 1998 <br />