1988-06-17_REPORT - C1981012 (2)

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the Golden Eagle Mine) since 1972. Annual runoff in the Purgatoire is dominated by snowmelt, with peak flows occurring in May and June. Summer and fall thunderstorms generally produce smaller peaks of short duration. Analysis of the 550 square mile drainage basin at the Madrid station indicates a low-yield watershed with the mean annual runoff volume measured at 28, 980 acre-feet. Three stations (PRS-1 , PRS-2 and PRS-3, Figure 1 ) were monitored on the Purgatoire River during the 1987 water year. Monthly data for the stations is presented in Table 1-1 , 1-2 and 1-3 in Appendix 1 . Annual data is summarized in Table 1-9 for 1984, 1985 and 1986 . The water at each of the three stations continues to be a calcium-bicarbonate type water with no significant changes in quality. Station PRS-1 is located on the Middle Fork above the New Elk Mine and acts as a control station without influence of mining. Tables 1-1 and 1-9 presents a summary of the data collected during the 1987 water year and for the previous three years . Flow at the station ranged from 5. 3 cfs to 122 cfs . pH ranged from 6 . 3 to 8 . 3 . Conductivity ranged from 109 to 467 . There has been no significant change in any of the parameters over three years of monitoring. Station PRS-2 is located below the confluence of the North and Middle Forks while Station PRS-3 is located one mile below PRS-2 and below all mining activities (Figure 1 ) . These two stations exhibit similar flow rates and water quality, however, the difference between these two stations and PRS-1 is the addition of the North Fork. Ranges and means for flow and water quality of the stations are presented in Tables 1-2, 1-3, and 1-9. All chemical parameters are similar to those of PRS-1 with a slight increase in conductivity, SAR , sodium and bicarbonate. These increases are not significant. The New Elk Mine Discharge (MDNE-1 ) is located on the Middle Fork of the Purgatoire River. All monthly data collected during 1987 12