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• Uam Assessment of Surface Water and AVF'S and Gnpaa ~.fxu'uu~u for nc~ Prnnu mrd .Id/acnu ,trcar Efforts were made in previous annual reports ui characterize baseline river water qualin. The purpose was to evaluate potential changes in surface water quality due to mining activities at the West Elk Mine. Continuous monitoring of stream Oows and periodic monitoring o(spring discharge rates are performed to provide the lung term data base from which possible impacts of mining can be assessed. Baseline Characterization of Water Quality and Streamflow A baseline characterization of North Furk water quality was performed in previow annual reports to evaluate the potential changes in North Fork water quality that could result Irom discharges at the West Elk Mine. Baseline characterization was performed downstream of the mine before the start of construction in August 1981. Data sources were the USGS stream gauging station on the North Fork near Somerset and the Mountain Cual Company's water quality monitoring station on the North Fork below the mine. Both stations were downstream of the surface facilities area and down- stream of all discharge points. Baseline data and analysis of these data are provided in the Mining and Reclamation Plan fur the West Elk Kline and in the first annual hydrology report. Comparison of Baseline Water Quality with Operational Data Of the ten parameters selected for baseline charac- terization, seasonal trends are apparent fur TDS. TSS, and total iron. The other parameters do not exhibit seasonal variation. Total dissolved solids arc least concentrated in the North Fork during the period between about May and July. The likely reason for this pattern is during this period high- TDS groundwater is diluted by snow runoff. Total iron is most concentrated during this period. Total suspended solids arc must concentrated Irom April to July. A compariwn of baseline water yualin' data in the North Furk of the Gunnison River with 199'_ monitoring data shows no significant changes in water quality in the North Fork. No apparent changes in the water quality of the Nunh Furk u( the Gunnison River can he anributed to affects ul mining during water year 1992. Mine Water Management and Impact Assessment The discussion of the mine water system and hydrologic impact assessment is organized by the (our sources of water: • North Fork water • sanitary wastewater • mine water, and • runoff from disturbed areas. Use and discharge of water from these sources i~ studied for its potential to affect the North Fork. North Fork Water During water year 1982, the conditional right to withdraw water from the North Furk was deemed absolute. When this water right is in priority, water can be pumped Irom the intake point w the freshwater swrage pond(s) within the surface facilities area. In average years, this water right is expected to he out of priority from July to Septem- ber. In 1977, it would have been out of priorin- frum April to September. In water year 1956. MCC's Mt. Gunnison Pipeline water right met quadrennial diligence for the conditional portion. Accordingly, an additional portion was deemed absolute by the Division d Water Court. That decision brought the absolute portion ro 0.55 cfs. Pond FW-1 provides for water storage. Water can also be stored in Sediment Ponds MB-1, MB-2, and MB-3 under a separate decree. Storage is usually limited to the maximum sediment level elevation. Transfer to FW-I is possible as outlined in the M S R Plan. Average withdrawals are not expected to exceed dOQOW gpd during the term u( permit and are likely to be on the order of 200A00 gpd during start-up o(longvvall operations in the Wcst Elk Mine and depending on produc- tion levels and requirements. During 1992 average C~