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_17_ is, therefore, a poor water source to the north of the tailings dam in the natural discharge areas. As a consequence of the radioactive pollution, this alluvial aquifer has been nominated as an E.P.A. Super Fund clean-up project. Also, because of extensive unreclaimed surface disturbances to the north of the Newlin Creek, Dorchester and G.E.C. operations, infiltration to the alluvial aquifers has probably been degraded. Furthermore, the ground water flow direction in the Vennejo Formation in the south and central portions of the syncline has been modified by past mining in the area. Subsidence features and improperly completed drill holes have resulted in communication between aquifers and depletion of perched aquifers. This, in turn, appears to cause flow to the east following the topography because the Vermejo Formation aquifers are no longer confined. Past mine dewatering has also modified the flow directions and the level of the piezometric surface by creating voids and drawing down the ground water level. The prevailing hydrologic balance is complex resulting partly from the impacts of previous mining in the area. C. Surface Water Surface water in the general area flows from the western mountains to the plains on the east, then north to the Arkansas River. The annual runoff for the basin is dominated by snowmelt from the nearby mountains, but peak discharges occur in response to infrequent, intense thunderstorms during the summer. Runoff in drainages within the general area corresponds to the location of the headwaters; the drainages originating in the Wet Mountains are perennial and the drainages originating in the basin are ephemeral. The estimated rainfall in the permit and adjacent area is approximately 14 inches, most of which falls between April and September. In view of the fact that the quality of the surface water in the Canon City Coal Field is better near the mountains and in the north central portion of the basin, several towns in the general area divert surface water from the mountain drainages for municipal use before the streams reach the natural recharge area of the Wet Mountain Fault and the upturned sedimentary units. Analyses of the water quality reports for the towns Rockvale and Coal Creek, show that water diverted from perennial drainages was calcium - bicarbonate in nature and exceeded the acceptable upper limits, based on E.P.A. standards, for domestic use for magnesium for Coal Creek water and barium for Rockvale water. The mainstem of the Arkansas River down to Canon City has goad water quality for human consumption according to E.P.A.'s standards, although metals such as cadmium, copper, lead and zinc are slightly elevated. This is due to the drainage from inactive metal mines located near the headwaters of the Arkansas River. Below Canon City, agricultural return flows affect water quality by increasing dissolved salt concentrations.