This report provides statistical summaries of rainfall, streamflow, suspended-sediment, and water-quality data collected in the Halawa, Haiku, and Kaneohe drainage basins before, during, and after construction of the H-3 Highway on the island of Oahu, Hawaii. Methods of data collection also are described. Data collected during water years 1983 through 1999 at eight streamflow and six stream water-quality gaging stations, and two water-quality stations located in Waimaluhia Reservoir are included. Physiographic data for all basins contributing to the 14 stream stations as well as brief land-use descriptions of the Halawa, Haiku, and Kaneohe drainage basins are provided.