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August 27, 2001 To: Bob Oswald From: Harry Posey Subject: Water quality results, Unidentified Project, Redcloud Creek/I-Jenson Creek, Midas Mining Company, M-2001-063 The subject documents were sent to me for comment Following are a few pertutent observations. I. Based on conversation wilt you, the data apparently were collected from the following points: Sample Name Description Portal Portal discharge prior to entering sediments upstream from Redcloud Creek Above Portal Redcloud Creek, upstream from portal discharge. Henson A Henson Creek, above Redcloud Creek Henson B Henson Creek, below Redcloud Creek 2. Samples were collected July 6, 2000. Flow at that time would be near the its lowest of summer discharge, would not likely contain sprang snowmelt, and would not represent "critical low flow" (winter). It is feasible that winter metal concentrations would be lower than those measured in July. 3. All samples have slightly alkaline pH. 4. All hardness values are low. Thus, low metals concentrations should be evaluated closely. 5. A few Al, Mn and Zrt values in the Portal and Redcloud Creek samples approach or exceed water quality limits for an aquaic life class l fishery. Having detailed, high quality information on record prior to muckutg with the portal discharge or the site would be useful. 6. Not knowing the composition of sediment ponds outside the portal, it is not possible to gauge their effects on water quality, but it is feasible that the sedbnents provide contar»inants to the portal discharge water. There is limited suggestion that water quality below the portal discharge to Redcloud Creek is degaded relative to Redcloud creek above the portal, but more sampling would be needed to affirm this suggestion. [t would be advisable [o determine this prior to the proposed mining. 7. No organic parartteters appeared in any analysis. 8. All of the analyses appear to have been analyzed at appropriately low de[ecion levels. 9. The lower pH, higher Zn and higher Nitrate values of the portal, relative to all other analyses, suggests that acid drainage may be forttting bt the adit drainage, and that underground sources of nitrate. possibly from prior blasting, are active. Satpling during winter and spring snowmelt is recommended far dte portal discharge, preferentially below the sediment pond, to more clearly evaluate the AMD potential. Overall, there is linu[ed evidence from these data the the portal discharge taps at least a slight source of acidic drainage and anthropogenlc sources of nitrogen. if that is the case, poorer water quality could be expected from the portal during spring snowmelt. Also, the effects of water rock interaction from the sediment pond is no[ evident in the data but camtot be dismissed. Sampling below the sediment ponds, either N the discharge itself or in Redcloud Creek below the site, is recommeuded.