Reclaimed water in the Eastern Municipal Water District of Riverside County,California, is used within the service area for agricultural irrigation.Owing to the seasonal demand for reclaimed water, storage/infiltration ponds were constructed in the Winchester, Menifee, and south Perris subbasins.Reclaimed water infiltrates from these ponds and enters the groundwater system. Little is known of the effects of the reclaimed water on groundwater quality. In cooperation with the Eastern MunicipalWater District, the U.S. Geological Survey began a study in 1995 to determine the quantity and fate of reclaimed water percolating from these storage ponds. Data compiled during the first phase of this study are presented in this report. Field reconnaissance of the Winchester, Menifee, and south Perris subbasins indicated the existence of many wells. Wellconstruction data for 115 of these wells were tabulated. Available historical waterquality and waterlevel data for 178 wells in the subbasins also were tabulated. In addition, water levels in 86 wells were measured during the spring and autumn of 1995. On the basis of these data, waterlevel contour lines were drawn and the direction of groundwater flow was determined.Three lithologic sections through the subbasins were constructed from drillers' logs of 26 wells.