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iii iiiiiiiiiiiu iii 999 MINED LAND RECLAMATION DIVISION Departmen7 of Natural Resources 7373 Sherman 5;.. Room 275 Denver. GO 80203 303 866-3567 FAZ 303 832-6106 STATE OF COLORADO o~ti ~i9> ..\: ~/ $. Foy Rome' Goerro~ Freo R Banu. Drvis~On D~re;tor DATE: April 18, 1990 T0: Dan T. Mathews FROM: James C. Stevens •~y RE: Chimney Rock Mine (Permit C-B1-0231 Review of 1989 AHR and Proposed Elimination of Hydrologic Monitoring -- I have reviewed the 1989 AHR for the mine and do not have any speciai concerns with it. The format of the report is good. The data, representing monitoring years 1985 thru 1989, are clearly presented. The reouired freouency of monitoring was apparently observed by the operator for the past year. Seasonal variations of stream flow and around water levels are not as we17 represented as a result of the quarterly monitoring schedule initiated in mid 1988. Now that the 4th quarter sampling is conducted in December, apparently no flow measurements have been possible for the surface stations during that calendar quarter for the past two years. As for surface water quality, there is remarkably little variation between stations upstream, in, and downstream from the mine. I have to believe the December 1989 conductivity value recorded at S3 was a bad reading: it differs too greatly from that at S2 of the same date and from a17 previous relationships of conductivity and dissolved solids. So far as I can tell, no significant impacts of the mine on surface water quality in Stollsteimer Creek have occurred. As for groundwater, 1989 was apparently a very dry year and water levels in most of the monitoring wells reflected this. Many levels were at or near recorded lows for their time of year. The quality of waters in alluvial wells W1, W5, and W7 is similar. Water in upstream well W7 actually is more highly mineralized than that in downstream wells. Asa result, no impacts of the mine on alluvial water quality can be documented. The overall higher dissolved mineral content of water in alluvial well A-1, located between wells WS and W7, has indicated from the beainninD of its use for monitoring that the well reflects somewhat different hydrologic conditions. Possibly less exchange of water between this area and the stream occurs; possibly the flood irrigation of the area of the AYF where this well is located has contributed to raisins the level of TDS in this water. This water, however, has remained reasonab]y consistent thru the period of sampling. Consequently, there are no clear impacts of the mining discernable.