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• Ponds within ttie proposed lease area have been <br />identified by CWI for the purpose of the mine permit <br />application (1983). `Topographic maps, aerial photographs and <br />direct field inspections !lave been used for the <br />identification of ponds. <br />A total of 32 ponds are indicated on Plate 9. N~ost of <br />them are man-made stock ponds; only a few of them are <br />apparently natural. At least eleven ponds are intermittent <br />(CWI, 1983) or subject to extremely low water during late <br />summer and fall. According to the USGS topographic map, 15 <br />ponds are intermittent. <br />The ponds are fed by surface run-off in most cases <br />which is why they are intermittent. Several of them are <br />located directly in the drainages and they are regularly <br />filled after any major precipitation or snowmelt. P. number <br />of them are fed by natural springs. These pond:, apparently <br />carry water for extended periods of the year. Elowever, as <br />all the springs in the area are fed by colluvial aquifers <br />that may dry out during the summer and fall, even these <br />ponds may dry out periodically. <br />• 3.3 GROUND WATER <br />Ground water conditions of the area have been studied <br />by CWI for permitting purposes (CWI, 1983), Dames & Moore <br />(1981) and by Brooks (1983). Brooks covered the area of the <br />proposed long-term lease. Most data on ground water <br />conditions used for the purpose of this subsidence study <br />have been obtained from the CWI and Brooks studies. <br />The Mesaverde Formation and Quaternary deposits are the <br />primary hydrogeologic units within the study area. <br />Quaternary deposits can be further divided into alluvial and <br />colluvial units. cacl~ of these units may contain ground <br />avatar. <br />Mesaverde Formation. Geologic and hydrogeologic <br />------------------- <br />conditions were investigated by extensive drilling during <br />1977 through to 1979. The formation is a thick series of <br />interbedded sandstone, siltstone, shale and coal, which dips <br />3 to 5 degrees to the north. 1'he results of drilling show <br />ti~at individual lithololic units are of a lenticular <br />character. 1'ney are not continuous between individual test <br />holes except Eor hollins Sandstone and some coal seams. <br />• <br />- 15 - <br />