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• -28- - The Minnesota Creek drainage extends approximately 53.5 square miles. Twenty-five percent of the drainage is located within the Mt. Gunnison No. 1 permit boundary. Minnesota Creek is fed by two major tributaries--the East Fork of Minnesota Creek and the Dry Fork of Minnesota Creek. The latter is fed by a trans-basin diversion (Deep Creek Ditch) from the Little Gunnison Creek. Water from the Lake Fork, South Fork, Hone Creek, South Prong Creek and Lick Creek drain into the East Fork of Minnesota Creek. The evaluation of flow within the Minnesota Creek drainage can only be considered an approximation due to Infiltration and seepage losses, seasonal variations in precipitation and potential evaporation and sampling difficulties. Nevertheless, approximately 1000 acre-feet is annually transferred from the Little Gunnison Creek to the Dry Fork of Minnesota Creek. and the average annual flow of the East Fork of Minnesota Creek is 19.920 acre-feet (Table 5). Irrigation ditches annually remove 20,000 acre-feet fron Minnesota Creek. Water quality data has been collected at several sites throughout the Minnesota Creek drainage. The data indicate that these waters are of a calcium bicarbonate type with relatively low total dissolved solids concentration. Two reservoirs are located within the Minnesota Creek drainage. Minnesota • Reservoir is located on Dry Fo-i:. It has a decreed capacity of 1,285 acre-feet. The actual capacity mdy be closer to 500 acre-feet, however. Beaver Reservoir is located on the East Fork of Minnesota Creek and has an absolute decreed capacity of 1,620 acre-feet and a conditional decree of 522 acre-feet. Both reservoirs store water for irrigation purposes and are filled during spring runoff. They are usually drained by late August or early ' September. Minnesota Reservoir may affect the water quality characteristics of the Dry Fork. Detention of Dry Fork flows in Minnesota Reservoir results in a decrease in total suspended solids (TSS), sl u t Increases in temperature, total dissolved solids. alkalinity and pH. The latter four mdy be a result of evaporation losses. There are over a hundred (100) springs located throughout the Mt. Gunnison life-of-mine area. Measurements indicate that spring flows generally decrease from a high in the early summer to a low in the fall. A number of the springs are ephemeral, indicating that their sources are small localized aquifers (i.e. landslide deposits, colluvium, lenticular sandstones, etc.). There are a total of thirteen (13) decreed spring water rights on or near the Mt. Gunnison permit area. Four separate drainages are located within or adjacent to the Orchard Yalley Mine; Terror Creek drains the eastern portion of the life-of-mine area; and East and West Roatcap Creek drain the western portion; Steven's Gulch is an ephemeral drainage between the Terror Creek and Roatcap Creek drainage basins • and drains the central part of the the permit area. These streams drain directly to the North Fork or are intercepted by the Fire Mountain Canal.