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<br />0920 <br /> <br />available beginning in Water Year 1979 (i.e., October 1978). For Water <br />Years 1979 and 1980, total annual precipitation is estimated to be 24.4 and <br />25.2 inches, respectively. <br /> <br />. <br /> <br />Surface water discharge leaving NOSR 1 has been monitored by the U.S. <br />Geological Survey since Water Year 1976. Total annual discharge has ranged <br />from a low of 529.9 acre-feet in Water Year 1977, to a high of 18,296 <br />acre-feet in Water Year 1979. For Water Years 1979 and 1980, total annual <br />surface water discharge in area-inches was 7.37 (18,296 acre-feet) and 6.96 <br />(17,269 acre-feet), respectively. A comparison of these fi9ures to the <br />estimated total annual precipitation of the same water years shows that <br />between 25 and 30 percent of total annual precipitation leaves NOSR 1 as <br />surface water runoff. A further breakdown of surface water runoff into <br />direct snowmelt runoff and baseflow indicates that for these water years, <br />between 8 and 15 percent of total surface water runoff is baseflow (0.59 to <br />1.07 area-inches or 1,482 to 2,652 acre-feet). <br /> <br />Overall quality of surface water on NOSR 1 is good and meets the U.S. <br />Environmental Protection Agency standards for drinking water. Sodium <br />adsorption ratios are less than 2, and only a low to medium salinity hazard <br />exists accordin9 to U.S. Salinity Laboratory Standards (1954), making this <br />water well suited for irrigation. Total dissolved solids range between <br />from slightly more than 225 mg/l to just under 400 mg/l, with annual <br />station averages from 265 to 350 mg/l. The best Quality water exists along <br />East Fork Parachute Creek and the highest dissolved solids concentrations <br />, are recorded at the Ben Good Creek gage. This pattern reflects a slight <br />north to northwestward increase in dissolved solids concentration across <br />the reserve. <br /> <br />Evapotranspiration on NOSR 1 is estimated to range up to approximately <br />19 inches. This estimate was based on a study of an adjacent property <br />(Wymore, 1974), and adjusting values from that study for the vegetation <br />distribution on NOSR 1. An independent evaluation of this factor from <br />water balance calculations for Water Years 1979 and 1980 show estimated <br />evapotranspiration to be 17.03 and 18.24 inches, respectively. This means <br />that 70 to 75 percent of total annual precipitation is lost through <br />evapotranspiration. <br /> <br />1-2 <br />