Introduction 1 Urban hydrology studies 1 Purpose and scope 2 Acknowledgments 2 Description of the study area 2 Geology, hydrology, and groundwater quality near the study area 4 Field and analytical methods 6 Site selection, well installation, and soil coring 6 Sampling of sediment from the recharge basin 9 Chemical analysis of water, soil, and sediment 10 Quality of recharge-basin water and ground water 13 Isotopic evidence for recharge 13 Major ions and trace elements 16 Organic priority pollutants and pesticides 17 Chemical concentrations in sediment and soil 17 Inorganic elements 17 Organic chemicals 24 Assessment of anthropogenic inputs 25 Laboratory elutriation experiments 26 Transport and loading of contaminated sediment 31 Comparison of basin-sediment inventories and storm-runoff loads 32 Lead-210 constraints on origin and loading of contaminated sediment 34 Summary and conclusions 35 References cited 36 1. Historical groundwater quality data from well 14S/20E-24K1 near the study site 6 2. Particle-size distribution in soil cores from two test holes adjacent to the recharge basin 7 3. Geologic log for test hole 1 adjacent to the recharge basin 8 4. Sand, silt, and clay content of soil cores from two test holes adjacent to the recharge basin 9 5. Particle-size distribution in sediment beneath the recharge basin 11 6. Concentrations of dissolved inorganic and total-recoverable organic constituents in water from the recharge basin and from two nearby monitor wells 14 7. Concentrations of elements and radioisotopes in soil cores from test hole 1 adjacent to the recharge basin 18 Contents I