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Response 1985 AHR Page 3 Comparison of Detection Limits and Receiving Steam Standards. Receiving Stream Element Detection Limit Standard Mercury 0.0005 0.00005 Cadmium 0.005 0.001 Molybdenum 0.05 0.01 Copper 0.02 0.01 Response: In reference to mercury, the receiving stream standard is below the existing detection limit for this element. The Colorado Department of Health; Water Quality Laboratory indicates that 0.25 ug/1 is the lowest reportable concentration using an AA, cold vapor method. TCC's lab will use USGS 1-2460- 78 automated cold vapor method to provide a future detection limit of 0.2 ug/1. In reference the other parameters TCC will advise the lab to utilize low level detection methodologies so that the detection limit meets the stream standard. MLRD Comment: Well 006-81-31 has much higher salt levels than other Wadge overburden sites. Has this well been examined to ascertain that it was completed properly? Do you have any other explanations for the high salt concentrations? Is well 006-81-30 an artesian well? The remarks column annotates the failure to provide depth data with the comment "flowing". Please elaborate. Response: The reported results do not appear to be representative and TCC will investigate the situation and advise the MLRD of the findings. Well 006-81-30 is a flowing artesian well. MLRD Comment: The Foidel Creek alluvial wells do not show any definite effects from mining from the hydrographs presented. However, future hydrographs should have an expanded abscissa of 20 feet rather than 35 feet. It is expected that water levels should rise in late summer with Foidel Creek's transition from an ephemeral to a perennial stream. Salt concentrations in the aquifer declined during the last two years at the downstream site, but increased at the two upstream sites.