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1979, and 1980 were 145, 158, 184, 133, and 103 days, respectively. In contrast, the longest no flow periods during • water yeazs 1981, 1982, and 1983 were 25, 4, and 19 days, respectively. The longest no flow period on record occurred during a 291 day period from June 16, 1977 to April 3, 1978. The changing flow pattem at USGS Station 09243800 is believed to be primarily the result of higher precipitation, but could also involve contributions of mine discharges from Pond A at the Eckman Park Mine. The maximum peak discharge on record for USGS Station 09243800 is 55 cfs recorded on Apri121, 1980. In contrast, during the drought period of water year 1977, the maximum peak discharge was only 0.16 cfs. Streamflow downstream of the mine is recorded at USGS Station 09243900 and at TCC Station 2005 (Figure 5-c). Data from USGS Station 09243900 located at the mouth of Foidel Creek describes streamflow conditions downstream of the mine plan area. During water year 1977, annual flows at this station average flow at USGS Station 09243800 upstream of the mine plan area. Likewise, during water year 1980, annual flows averaged 4.34 cfs or about two times the flow at the upstream station for the corresponding period. Maximum peak discharge for the period of record from October, 1975 through September, 1985 was 90 cfs recorded on April 22, 1980. The maximum peak discharge during the drought year of 1977 was only 2.5 cfs recorded on March 26, 1977. ALog-Pearson Type III flood frequency analysis of floods on Foidel Creek at Station 09343800 indicates a 10-year peak flow of 88 cfs and a 100-year peak flow of 159 cfs (see Table 10, Surface Water Data). The 7-day, 10-year low flow on Foidel Creek above and below the mines was zero prior to any mine discharge. Comparison of hydrogtaphs in Figures 5-a through 5-c show the similarity of flow patterns between the upstream and downstream stations on Foidel Creek. The baseline record from October, 1975 to October, 1979 depicts an intermittent stream with relatively long periods of now flow lasting from June or early 7uly until February or March of the following year. Starting in the fall of 1980 the streamflow pattem has shifted to a much shorter no flow periods and higher mean annual flows partly as a result of higher precipitation and partly due to effects of surface mining. Since the initiation of underground mine discharge from the Foidel Creek Mine in the fall of 1983, streamflow at Station 09243900 near the mouth of Foidel Creek has become perennial. Middle Creek is also an intermittent stream. The USGS is measuring streamflows on Middle Creek at Station 09243700 as shown on Map 13, Twentymile Park Hydrology. During the ten year monitoring period starting in October, 1975, annual mean flows have varied from 0.5 cfs in water year 1977 to 13.2 cfs in water year 1984. The longest no flow period on record was a 251 day interval from July I5, 1977 through March 27, 1978. Perennial flow occurred during water years 1980, 1983, 1984, and 1985(Figure 5-d). Since this station is above any influence from mining it serves to illustrate the shift in flow regimes resulting from climatic conditions. The 7-day, 10-year no flow for Middle Creek is zero. The maximum peak flow on record was 329 cfs recorded in water year 1981 on July 2. A Log-Pearson Type III flood frequency analysis for the period of record indicates a 10-year peak flow of 216 cfs and a 100-year peak discharge of 807 cfs (see Table 10, Surface Water Data). Streamflow data for Fish Creek have been collected above and below the mine at the stations shown on Map 13, Twentymile Park Hydrology. Table 10, Surface Water Data, includes streamflow records for Fish Creek downstream of the mine plan area at Station 1003 and upstream of the mine plan area at Station .1001. Additional Flow data are provided at an intermediate site, Site 26 (Station 1002). Variation in streamflow along this reach of Fish Creek is illustrated in the monthly hydrograph plots provided in Figures 5-e, 5-f and 5-g. These hydrographs show that Fish Creek is a perennial stream that gains considerable flow during the months of March through June as it traverses this reach through Twentymile Park. During baseflow periods Fish Creek does not appear to gain flow over this reach. Baseflow levels vary considerably from year to year on Fish Creek. Data from the upstream gauging Station 1001 indicate baseflow rates from about 1 cfs in dry years to as high as 8 cfs in the relatively wet years of 1984 and 1985 (see Table 10, Surface Water Data). The downstream gauging Station 1003 shows comparable ranges for baseflow • conditions. Permit Renewal No. 3 2.04-32 12/10/98