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• 1999 AHR McClave & Munger Canyon Mines Page 3 Future Water Inflow As the mine extends farther to the east and then north as shown in Figure 2.1.1 of the permit application, it is possible that water will be encountered. Figure 4.2-3, of the permit application, shows the saturated strata may again be encountered approximately 400 feet ahead of the east mains. Mining into the saturated coal bed will produce mine inflows as the coal bed is dewatered. Experience gained by mining in the graben indicates initial flow rates will be much greater than the flow rate after mining. If water is once again encountered, its existence will be documented and detailed in future reports. As shown on Figure 4.2-3, the saturated strata appear to outcrop in the valley formed by the north split of Munger Canyon. Since the strata in the area dip at four percent to the northeast water may be infiltrating the seam along the valley bottom. Any water infiltrating the strata at this location will flow down dip until the aquifer is totally saturated unless there is an area where water may escape. The elevation of the saturated zone would approximate the elevation of the outcrop (5,600 ft) if no water flows out of the strata at a lower elevation. The elevation of the existing faces is approximately 5636 ft. There are no known springs or seeps that would allow escape of the water from the zone of saturation so it can be expected the coal seam will be saturated near the outcrop elevation. • MUNGER CANYON MINE To date there has been no water encountered by this mine; therefore, there has been no effect on the hydrologic regime of the area. The current mine workings are shown on Figure 4. Table I documents that no water was used at the mine this year. PRECIPITATION Based upon Bureau of Land Management records from a rain gage in Ashford Canyon, the 1999 water year experienced 16.02 inches of precipitation compared to average precipitation of 19.03 inches. The rain gage is not located at the mine but about 3.5 miles north at an elevation of 5895 feet compared with 5610 at the portals. The daily rainfall record is detailed on Table 2. The greatest 24 hour precipitation event during the year, 1.08 inches, occurred on May 3`d. Figure 2 presents a graphical comparison of the 1999 total monthly precipitation and the average monthly precipitation for the period 1977 through 1999. EFFECT OF THE MINES ON THE EAST SALT CREEK REGIME Surface Water Due to the limited disturbance of the mines there is little chance any significant effect on the quantity or quality of the surface waters near either mine sites has occurred. As the Division notes in its approval package for the Munger Canyon Mine, the total area that will be disturbed by both mine sites amounts to 0.12 percent of the area of the East Salt Creek drainage basin above the mines.