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The BLM has performed gain-and-loss measurements of stream discharge at six sites, three on Rapid Creek, two on Cottonwood Creek, and one on Oak Springs Creek. "The data indicate slight downstream gains of flow in all reaches" (Brooks, 1986). There has been no noticeable effect on the flow in the creeks Protective pillars are designed to protect the creeks from subsidence, and the creeks should remain intact during and after mining. The extreme worst case impact would be subsidence of the adjacent topography and minor ponding of surface water. The ponding would create small sediment traps until the ponds were filled-in with collected sediment. Because of the steep gradient of Rapid and Cottonwood Creeks and the steep topography adjacent to the creeks, this ponding effect, should it occur, would be temporary. The surface flow losses occurring in the ponding areas is expected to be minimal because of the small capacity of the depressions relative to the steepness of the topography in the drainage basins. Effects on Dams and Reservoirs in the Rapid Creek Basin Seven reservoirs are used to store water in the Rapid Creek basin. All seven of these reservoirs are located in the upper reaches of Rapid and Cottonwood Creek, and none of the reservoirs overlie the Roadside Mine. Most of these reservoirs are in areas where coal will not be mined. Therefore, the BLM determined that Rapid Creek Reservoirs No. 1 and 2, Vincent Reservoirs No. 1 and 2, and Palisade Reservoir would not be affected by underground coal mining (Brooks, 1986). Cabin Reservoir is within the possible subsidence angle-of-draw. Cabin Reservoir is located in the extreme south-east corner of the permit area, and the area is not due to be under mined until around 20Q1 (see Exhibit 5, Tab Section 12). Protective pillars will be left for all areas within the angle-of-draw below this reservoir. Therefore, there will be no impact to the reservoir. 19-3 (New 3/1 /96)