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-17- The ground water flow direction in the Vermejo Formation in the south of the syncline has been modified by past mining in the area. Subsidence features and improperly completed drill holes from historic mines 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 aquifer is 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. It is difficult to quantitatively describe the prevailing hydrologic balance because of the complex nature of the system resulting from the impacts of previous historic mining in the area. C. Surface Water Surface water in the general area flows from the Wet 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 Rockvale and Coal Creek, provided by the Small Operator's Assistance Program report prepared by J.F. Sato and Associates, 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 and barium. The mainstem of the Arkansas River down to Canon City has good 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 solids concentrations. Probable Hydrologic Consequences of Dorchester No. 1 Mine A. Ground Water The proposed permit area lies on the southern terminus of the Chandler Syncline, where the Dorchester No.l Mine is currently mining the Red Arrow and the Dirty Jack O'Lantern Seams of the Vermejo Formation.