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underdrain has ranged from 1,600 to 3,100 umhos/cm. The conductivity of the discharge from the south underdrain has ranged from 3,300 to 5,300 umhos/cm. The middle underdrain has never discharged The disposal of mine waste exposes fresh surfaces of saline shales and sandstone for leaching by water infiltration from rainfall and snowmelt, thus influencing the quality of subsurface flow. The salt pickup rate depends heavily upon the local hydrology. A study done by McWhorter and Rowe in 1976 suggests that total salt pickup can be estimated from saturated spoil analyses and a knowledge of the local hydrology of mine waste disposal area. This model would provide a method of evaluating the impacts of mine waste disposal on water quality. The permeability contrast found in the pile will cause most of the leachate water to perch within the refuse pile and above the native soils. A shallow water mound will build within the pile and cause the water to migrate laterally to small seepage areas at the edge of the site. Water flows, during most of the year, through the north and south underdrains. The middle underdrain has never flowed. Some seeps have been noted towards the base of the mine bench. b. Surface Water Effects and Mitigation The following discussion is oriented toward those impacts which may affect Hubbard Creek. Effects upon the North Fork of the Gunnison River will be similar, but of a much smaller magnitude. Hubbard Creek runs through the permit area between the mine bench and the former location of the coal stockpile and is the only tributary of the North Fork of the Gunnison which may be affected by operations at the Blue Ribbon Mine. Blue Ribbon Coal Company operated an adjudicated well completed in the alluvium of Hubbard Creek adjacent to the mine bench. Water from this well was used for sanitary and industrial purposes. Water was produced at an average rate of about eight gallons per minute. Blue Ribbon Coal Company obtained conditional rights for the use of this water and ditch and storage rights for the now reclaimed Pond No. 1, which served as a source of augmentation water to charge the well. The water rights for the Blue Ribbon Mine have been abandoned. The removal of eight gallons per minute (gpm) is a negligible reduction in the average flow of Hubbard Creek. For example, in 1980, removal of eight gpm equalled only 0.6 percent of the low flow of three cfs. Both the -26-