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the range of hydraulic conductivities for these materials. The eastward gradient indicates ground water flow occurs along the base of the alluvial valleys. Seasonal water level records indicate that the water table fluctuates, corresponding to the rate of recharge from upstream. In the spring, the alluvium is more saturated than during the fall (see alluvial well data in Tables 3, 4 and 5). The major features which influence ground water flow in bedrock, and hence, affect piezometric elevations in the permit area are the dikes and faults that have intruded the local strata, Maitland and Gordon Arroyos that have eroded channels into the bedrock formations and the underground mines that cross geologic units and boundaries. The dikes and faults are geologic barriers confining the local movement of ground water. The arroyos act es hydrogeologic barriers affecting the configuration of historical mining. To avoid substantial inflow, the arroyos were not substantially undermined. The mine workings are now considered major hydrologic conduits. • To facilitate discussions, the mine area has been divided into three hydrogeologic sectors, correlative with CCMC's mining program proposed for this area. These sectors are shown on Figure 1. Hydrogeological SeetorI Sector I is bounded by the dike along the southern boundary of the permit area and on the north by Maitland Arroyo. Three major mines exist in this sector and are located in the Lower Robinson, Lennox and Cameron coal seams. The mines in the Lennox and Cameron seams are considered to be hydrostatically connected by either mine adits or numerous drillholes in the area. Observation wells in the various strata throughout the sector all have similar static water levels indicating hydraulic interconnection. It is significant to note that the static water level elevations for these coal seams are roughly at the same elevation at which each of the coal seams subcrop in the alluvium beneath Maitland Arroyo. • -8-