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-27- <br />Two reservoirs are located within the Minnesota Creek drainage. Minnesota <br />Reservoir is located on Dry Fork. It has a decreed capacity of 1,285 <br />acre-feet. The actual capacity may be closer to 500 acre-feet, however. <br />Beaver Reservoir is located on the East Fork of Minnesota Creek and has an <br />absolute decreed capacity of 1,620 acre-feet and a conditional decree of 522 <br />acre-feet. Both reservoirs store water for irrigation purposes and are filled <br />during spring runoff. They are usually drained by late August or early <br />September. <br />Water quality data has been collected at several sites throughout the <br />Minnesota Creek drainage. The data indicate that these waters are of a <br />calcium bicarbonate type with relatively low total dissolved solids <br />concentration. <br />There are over 100 springs located throughout the Mt. Gunnison life-of-mine <br />area. Measurements indicate that spring flows generally decrease from a high <br />in the early summer to a low in the fall. A number of the springs are <br />ephemeral, indicating that their sources are small localized aquifers (i. e. <br />landslide deposits, colluvium, lenticular sandstones, etc.). There are a <br />total of 13 decreed spring water rights on or near the Mt. Gunnison permit <br />area. <br />Precipitation and Runoff <br />Only two precipitation stations exist for the North Fork River Basin, one at <br />Paonia and one at Wilcox Ranch. Recently, the Wilcox station has been taken <br />over by WECC. Since these are located near the North Fork of the Gunnison <br />River, they may not be representative of the total watershed. Isohyetal lines <br />can be used to show average precipitation that falls on the watershed. Figure <br />5 represents mean annual precipitation and Figure 6 illustrates May to <br />September precipitation of the years 1931 to 1960. All values were obtained <br />from maps drawn by the U. S. Weather Bureau. Table 6 summarizes precipitation <br />data for both the north and south sections of the watershed. Comparing these <br />isohyetal maps with Figure 7 shows that precipitation patterns are strongly <br />influenced by topography. <br />During the period May through September, the amount of precipitation which <br />falls upon the watershed is less than the potential amount of water lost to <br />evapotranspiration (PET). In other words, transpiration by native vegetation <br />and evaporation consumes most of the precipitation and also will remove water <br />from the soil profile. For those areas where cash crops such as apples," <br />peaches, and the like are grown, irrigation water is removed from the North <br />Fork of the Gunnison River and applied on such lands. <br />Surface water in the general area is dominated by the North Fork of the <br />Gunnison River. Flow records exist fora U.S.G.S. Gaging Station near <br />Somerset. Data from this station (Table 2) show inflows to the area and <br />releases from Paonia Reservoir. Outflow from the basin is not as easily <br />determined. For example, the nearest station to Paonia is located on the <br />Gunnison River near Lazear, Colorado, 11 miles southwest Pf Paonia. Such a <br />