Geohydrologic information on the area within and surrounding the Irondequoit Creek basin near Rochester, in north-central New York, is presented on five maps at 1:24,000 scale indicating: (1) locations of glacial geomorphic features, (2) surficial geology, (3) soil permeability, (4) potentiometric-surface altitude and directions of groundwater movement, and (5) groundwater recharge and flow patterns. Also included are 20 geologic sections showing statigraphic relationships, aquifer composition, and depth to bedrock. Each map includes a short text and a list of references. Results indicate that groundwater within the basin flows northward to Irondequoit Bay and Lake Ontario and that the groundwater drainage system is considerably smaller than the overlying surface drainage area. These maps, based on available records and published data, depict the location of major recharge areas, relative rates of recharge, and the direction and rates of groundwater flow within the basin for use in aquifer management. (USGS)