2008-11-24_PERMIT FILE - C1996083A (14)

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2.04.7 Hydrology Description (2) Surface Water Information. (a) and (b) The surface water information is organized in the following categories; 1) Watershed, the river and stream network beginning at the Colorado River; 2) the North Fork of the Gunnison River; 3) streams draining the permit and adjacent area; 4) stockponds within the permit and adjacent area; and 5) surface water on the mine site. Watershed The proposed mine plan and adjacent area lie within the Upper Main Stem of the Upper Colorado River Region in Colorado. The Upper Main Stem is composed of nine major sub-basins: Middle Park, Eagle River, Roaring Fork, Rifle-West Divide, Grand Valley, Upper Gunnison, North Fork, Uncompahgre, and Whitewater. Altitudes range from about 4,300 feet on the Colorado River at the Colorado-Utah state line to over 14,000 feet on the Continental Divide, which forms the eastern margin of the watershed. Only the North Fork may be affected by the Bowie #2 Mine. North Fork of the Gunnison River A USGS gauging station (No. 09132500) is located 2.3 miles east of Somerset and 4.8 miles upstream from Hubbard Creek. The period of record is October 1933 to current year. The gauge is awater-stage recorderwith satellite telemetry about 6280 feet above sea level. According to the report for the water year October 1993 to September 1994, the average annual discharge of the North Fork of the Gunnison River is 330,500 acre feet, which drains 526 square miles with an average elevation of 8,700 feet. This is a water yield of 628 acre-feet per square mile. Water flows and water quality in the North Fork are strongly influenced by water control through Overland and Paonia Reservoirs, by water withdrawal from several irrigation canals, and by reflow from irrigated lands back into the river. Withdrawals at Somerset (Fire Mountain Canal), between Bowie and Paonia (Stewart Ditch), and just above Paonia (Farmers Ditch) withdraw significant flows and cause significant dewatering of the river. Some of this water returns to the river near and below Paonia. Irrigation has significant effects on water volume and quality of the North Fork. It contributes to reduced flows and increased salinity, nutrients, and probably herbicide/pesticide levels. Indirectly, lower flows contribute to higher summer temperatures. The municipality of Hotchkiss (below Paonia), and several smaller communities along the valley and mesas are also sources of nutrients as the result of effluents from discharges directly into the river and through the groundwater. There is little industrial use or discharge of water to the North Fork, particularly in the upper part of the valley, although several coal mines have operated in the past and are presently operating. PR-10 2.04 - 31 - 09/26/08 ~Pl~eouE® is/zy/88