1981-08-20_GENERAL DOCUMENTS - C1981038

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-22- Geological Survey (U.S.G.S.) records indicates that for the years 1922 through 1932, a gaging station existed on the North Fork of the Gunnison River near Paonia. Also, for the years 1932 through 1950, a gaging station existed in Somerset. These two stations are important since Paonia Reservoir was not yet constructed and thus did not affect inflows to the basin. Use of these stations allows determination of approximate inflows to the North Fork of the Gunnison River contributed by the watershed located within the boundaries of Figure 1. The average monthly flows are illustrated on Table 2, along with the inflows to the North Fork of the Gunnison River from Minnesota Creek. These figures were utilized to determine the amount of outflow via the North Fork of the Gunnison River from the basin. Obviously, such predictions are not entirely correct. For example, less than 3 years of data existed for Minnesota Creek and 1 year (1977) included drought conditions. However, for purposes of this analysis, we believe that such figures provide the basis for determining the impact of development by the Mt. Gunnison mine which, as can be seen in Figure 1, has a substantial portion of it's lease area located in the Minnesota Creek drainage basin. Note that column 5 of Table 3 gives the net drainage to the North Fork of the Gunnison River between Somerset and Paonia. As more data is available, these values will become more accurate. Mass Balance Table 5 provides a mass balance analysis of the basin illustrated in Figure 1. On a mean annual basis, there appears to be a net increase in the change of storage. However, for the May to September time period, it appears that a-deficit condition exists. Part of this is undoubtedly due to the inadequate data which were available for the analysis. However, even with additional' data, it appears that the change in storage will still be negative for this particular time period. This is due to low precipitation from May through September. At present, approximately 30,000 gpd is pumped from Stevens Gulch and used for coal spraying, dust control, fire control and potable water supplies. This depletion has been augmented by an approved augmentation plan through Division 4 Water Court (see Augmentation appendix in Volume 2) 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. Some evaporation of water in the ponds no doubt occurs, but this is expected to have a minimal effect. Another consumptive use of water by Colorado Westmoreland, Inc. will be water adsorbed on coal which is trans- ported, out of the basin. No data has been provided by Colorado Westmoreland, Inc. on this consumptive use. However, with the data required in the mine inflow stipulation on page no. 11 , Colorado Westmoreland, Inc. will be supplying this information annually to the Division. The Western Slope Carbon Hawk's Nest mine, located on the North slope of the basin above Somerset, utilizes it's surface water rights and rights to mine inflow water (Appendix XIII, Volume 3) 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 Western Slope Carbon permit r application) .