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• - OSM, November 1987. Mt. Gunnison No. 1 Mining Plan Modification Environmental Assessment. Additionally, OSM bases this finding on the following reasons. C. Reasons The proposed mining plan modification would cause no new disturbance other than mining-induced subsidence. A total of about 2,700 acres is expected to subside due to all mining operations in the permit area. No subsidence or surface disturbance is expected in the 35.5-acre area in the Minnesota Creek drainage basin. The proposed mining plan modification would not result in significant damage to any important historic, cultural, or scientific resources in the permit area. A special condition of approval is recommended to protect unsurveyed cultural resources in the event that new subsidence or cultural resources information indicates that cultural resources may be affected by subsidence. The SHPO concurred with OSM's determination in a letter dated December 15, 1989. • While drainage patterns may be affected slightly in the permit area, subsidence is not expected to adversely affect surface flow in the ephemeral streams of the permit area. All drainage would continue to flow to the North Fork of the Gunnison River. There would be no changes to the drainage patterns of the Minnesota Creek watershed, nor any depletions of surface water flows in the Minnesota Creek watershed. The worst-case depletion of springs and seeps would have a very minor impact on the quantity of water available in the basin. WECC has committed to develop undeveloped springs to mitigate the loss of water from existing developed springs. Subsidence is expected to be minimal in the areas where stockponds are located. If subsidence does affect the viability of a stockpond, WECC has committed to replace or repair any ponds to mitigate any loss of water due to mining activities. Fracturing of strata above the B seam is expected to have minimal, if any, effect on aquifers below the B seam. The cumulative mine water inflow projection is 42 gpm. Treatment capacity for the mine water inflow is 200 gpm (in • addition to the treatment capacity for surface runoff from the surrounding drainage area). Currently, treatment is required only for inflows from the active mining areas.