Reports on the hydrology of Oklahoma have been issued by the U.S. Geological Survey since 1901. This bibliography lists reports on hydrology in Oklahoma prepared by the U.S. Geological Survey and the principal State cooperating agencies, the Oklahoma Geological Survey and the Oklahoma Water Resources Board. Of the nearly 350 reports issued from 1901 through 1988, about 200 have been concerned primarily with groundwater; the remainder have dealt with some aspect of surface water, water quality, or geology. The reports are listed by agency and report type, and are indexed both by author and subject. (USGS)