Groundwater levels are measured periodically in a network of 92 observation wells in Wyoming, mostly in areas where groundwater is used in large quantities for irrigation or municipal purposes. The program is conducted by the U.S. Geological Survey in cooperation with the Wyoming State Engineer. This report contains hydrographs for 92 observation wells showing water-level fluctuations from 1980 through September 1989. Also included in the report are maps showing locations of observation wells and tables listing well depths, use of water, geologic source, records available, and highest and lowest water levels for the period of record. (USGS)