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1993 Annual Hydrologic Report • Page 5 subjecting fathead minnows to various dilutions of effluent in receiving water for 4 days and subjecting Ceriodaphnia dubia to various dilutions for 2 days. The chronic test is a 7 day test for both species. Both tests look primarily at mortality during the test period. Data pages SL-1 and SM-1 are summaries of the final percent survival at the individual effluent dilution ratios. Discharge from outfall 001 and 002 are combined proportional to the total discharge for the previous month to form one sample. In June 1993 one analysis of the combined discharges exceeded 50~ mortality and additional testing was done on the two individual sites. By changing pumping patterns underground, the water returned to having an acceptable affect upon the flies and fish. GROUND WATER The ground water monitoring points on Cottonwood and Rapid Creeks were monitored twice during the year. Results of the monitoring are listed on data page GA-2. Diagrams G93-1 thru 6 show a graphical representation of the depth to water in these wells • since monitoring began in 1984. The GWMS-O1 wells continued to show similar sharp variations. The GWMS-02A well which is developed only at the base of the alluvium showed a slight variation but not related to expected seasonal fluctuations. GWMS-02B which is developed the full length of the alluvium showed sharp seasonal variation. The GWMS-03 wells showed similar but sharper than normal seasonal variations. Piezometers at the Cameo Refuse Disposal Areas (CRDA) No. 1 and No.2 continued to be monitored quarterly. Data page GC-2 includes measurements for this year. A graphical representation of these depths to water are shown on Diagrams G93-7 thru 13. The water level in O1 was slightly higher than in the previous 3 years. The water level in OlA showed a wide fluctuation during the year and averaged 7' higher than the previous year, Water was again recorded in 02 after 3 years of being dry. The water level in 03 was higher than usual also. The water level in these CRDA #1 piezometers appears to be related to the high precipitation during the spring of 1993. The 3 piezometers on CRDA #2, 04, 05, and 06 showed only a slight increase in level during the year. Table G93-1 is a water analysis of a sample taken from the O1 piezometer. As can be seen in the trilinear diagram on Diagram G93-14, this water is a Na HCO3 type and is similar to mine inflows and mine discharges. • The piezometers at the unit train loadout were monitored this year as a result of questions in our permit renewal process. Data Page GB-1 is a listing of water levels taken on these wells