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-44- The Orchard Valley Mine pumps approximately 30,000 gpd (23.02 acre-feet/year) from Stevens Gulch for coal spraying, dust control, fire control, and potable water supplies. This depletion has been au mented by an approved augmentation plan through Division 4 Water Court see Auymentation appendix in Volume 2, the Orchard Valley permit application), which utilizes releases from East Beckwith No. 1 Reservoir, located in the Anthracite drainage, to replace water removed from Stevens Gulch. Most of the potable water supply used for showering, etc. is treated at the site and released to the sediment ponds. The loss due to evaporation of the water in the ponds is expected to have a minimal impact on water yields of the North Fork of the Gunnison River. Another consumptive use of water by the Orchard Valley Mine will be water adsorbed on coal which is transported out of the basin. No data has been provided by Colorado Westmoreland, Inc. on this consumptive use at the mine. Colorado Westmoreland, Inc., will be supplying water consumption information annually to the Division as a stipulated condition to their permit approval. The worst-case depletion to the flow in the North Fork (23.0L acre-feet/year) for a 250-day work year should be O.OU6% of the mean annual flow in the river. The Western Slope Carbon Hawk's Nest Mine, located on the north slope of the basin above Somerset, utilizes its surface water rights and riyhts to mine inflow water (Appendix XIII, Volume 3 of the Hawk's Nest permit application) to meet the water requirements for mining operations, wash plant operations and domestic use. Water rights held by Western Slope Carbon are adequate to cover the consumptive use in their mine operations (pages 2.04-29 to -33 of the Hawk's Nest permit application). Western Slope Carbon estimates that the Hawk's Nest Mine will consume '215 acre-feet of water per year, which amounts to O.U52% of the mean annual flow of the North Fork of the Gunnison. For the ARCO Mt. Gunnison No. 1 Mine, the worst-case scenario would be if the 15U acre-feet per year of water used for spraying the coal and for the potable water supply were entirely removed from the basin. On the average, this would amount to approximately 12.5 acre-feet of water each month. From Table 9, it appears (from Column 5) that the months of August and September will be the critical months for removal of water from the watershed. In reality, most of the water used for potable water will be returned to the North Fork of the Gunnison River. Consequently, ARCO's main concern will be the water lost due to spraying activities. ARCU will store water diverted from the North Fork in a storage pond adjacent to the river. The total estimated worst-case depletion (150 acre-feet per year) would amount to only 0.04% of the mean annual flow of the North Fork. (See materials submitted by ARCO L'oal Company, December 15, 1981, in response to pe rnrit Stipulation No. 7.) U.S. Steel has not submitted an estimate of the total water consumption in the Somerset Mine. The Division, therefore, has made the assumption that water consumption at the Somerset Mine is similar to the proposed maximum water consumption in the Mt. Gunnison No. 1 Mine. This assumption is based on the close proximity of the mines, the similarity in mininy methods, coal handling, manpower requirements, and total annual coal production. This estimated water consumption would amount to 150 acre-feet per year, or 0.04% of the mean annual flow in the North Fork of the Gunnison.