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combination of aquifer recharge with water from the Wadge impoundment and the <br />precipitation noted in prior years. <br />In the Cow Camp Creek (tributary of Fish Creek) alluvium, water quality is measured at two <br />wells. Well 46-A has a MgCaNa-S04 type water with water quality notably different from <br />other alluvial eater in the Seneca Mine area. This well exhibited a high TDS <br />concentration prior to mining in the vicinity (2,068 mg/L in November 1982). High TDS <br />values are also exhibited in the alluvium upstream of this well at Spring f!5 (14,200 mg/l <br />in September, 1985). Apparently, eater quality throughout the alluvium is affected by a <br />high concentration of naturally occurring salts that are further concentrated by <br />evapotranspiration. Mine runoff and spoil spring discharge has caused TDS values at Well <br />46-A to increase further, up to October 17, 1986 (with a TDS of 3,498 mg/l), after which <br />TDS values have steadily decreased with a June 25, 1991 TDS value of 2,320 mg/l. This is <br />in spite of the fact that TDS values upstream at the 004 pond have increased steadily <br />since 1982 (with a TDS of 3,344 mg/l on June 11, 1991). <br />The second cell in the Cow Camp Creek alluvium, Well 69-A, was completed in the summer of <br /> 1988. It is Located approximately one and one-half miles downstream of Well 46-A. The <br /> water samples at this well displayed a CaM g-S0 <br />type water. The aver age TDS values for <br /> 4 <br /> this well in 1991 were 44 percent higher than Well 46-A. This is most likely a result of <br /> the high amount of salts in the soils of Twentymile Park (see later discussion of the <br /> Twentymile Park and Fish Creek surface water systems). <br />Well 68-A, completed in the Bond Creek alluvium, was also completed in the summer of 1988. <br />It is located approximately two miles downstream of the 008 pond. The eater samples at <br />this well displayed a CaM 9-504 type water. TDS values (5,089 mg/( average, 1991) were 50 <br />percent higher than observed at Well 69-A on Lou Camp Creek (3,395 mg/L average, 1991), <br />and were significantly higher than measured at NPDES 008 (1,367 mg/L average, 1991). <br />Local alluvial geochemistry most likely accounts for this difference. <br />Lennox-Wedge Interburden. Two cells are used to monitor the eater quality of this strata: <br />21-LWI and, 42P1-LWI. Well 42P1-LWI did not have enough eater in its casing to sample [his <br />year. Well 21-LW1, situated out of the permit boundary and downdip of prelau mining and a <br />fly ash pit operated by Colorado-Ute Electric Association, displays a CaMg-504HC03 type <br />water. TDS levels have actually dropped in the last five years, as indicated by Table 6 <br />• <br />7 <br />