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<br /> the Stewart Ditch landslide. Average daily low flows in the North Fork <br />' during Water Year 1986 was 80 cfs orb, January 15, 1986. The maximum <br /> withdrawal at the intake is 460 gpm~'with both pumps operating. This is <br />' less than 1.38 of the observed average daily low flow in the river during <br />the water year, were the pumps operating during low flow conditions. <br /> Sanitary Waste Water <br />' <br /> A sanitary waste water treatment plant was constructed and coi~leted in the <br /> fall of 1982. <br />1 ,J:/;; <br />During Water Year 1986 discharge from the waste water treatment plant <br /> averaged 4870~gpd. This discharge is about 0.018 of the average daily flaw <br /> of BO cfs observed in the North Fork during the year. <br /> <br /> Analysis presented in the quarterly reports show monitoring cesults from <br /> discharges from the waste water treatment plant as required under NPDSS <br /> Permit No. ~-0038776. The results of analysis suggest the waste water <br />' discharge has no measurable effect on water quality in the North Fork <br /> Gunnison River. <br />Mine Water <br />1 Mine inflows during Water Year 1986 were small. The total mine water <br />inflow was 31.2 acre ft. during the year. The total water exiting the mine <br />is estimated to be 28.8 acre feet. The quality of mine water is considered <br />good and offers no problem for treatment and discharge. <br />' Mine water was discharged exclusively from Sylvester Gulch. Table 1.4-1 <br />shows the results of discharge sampling. <br />' Mine water inflow for Water Year 1987 is expected to be similar to that <br />experienced during Water Yeaz 1986. Mine water would be expected to have <br />water quality characteristics similar to that reported in Table 1.4-1 and <br />1.4-2 in 1987. <br />' Because of the small quantity of mine water anticipated, any discharge from <br />ponds could normally be dominated by water quality characteristics of <br />disturbed area runoff as described in the following section. <br />' Runoff from Disturbed Area <br />Overland runoff from snowmelt• and precipitation within the disturbed areas <br />' is routed to one of six sediment ponds on the mine site. The six sediment <br />ponds are designed to contain the predicted runoff from a statistically <br />determined 10 year, 24 hour precipitation event as well as a calculated <br />' sediment storage volume. The ponds are also designed to safely pass the <br />overflow from a 25 year, 24 hour precipitation event. The Mt. Gunnison <br />Mine site receives much of its annual precipitation from snowfall during <br />the winter months. When warmer weather begins in late February, March or <br />' April, most runoff to the sediment ponds is from snowmelt. It is entirely <br />possible for a volume of runoff greater than the 10 yeaz, 24 hour <br />precipitation event to result from snowmelt or snowmelt coupled with asmall <br />1 precipitation event. <br />1 ~lg, <br />