Index to water resources data for Illinois

This index to water resources data for Illinois includes 1,275 sites where surface-water and ground-water data were collected through December 31, 1975. The index is the first comprehensive tabulation of data collected in Illinois by the U.S. Geological Survey; data collection began in 1903. Information included are the county code, drainage area, datum, type of data available, period of record, where data are filed, and the name of the current cooperating agency. The surface-water index is listed sequentially by station number and also alphabetically by station name. Station numbers for the ground-water index are grouped by counties. The hydrologic unit index shows all sites and is listed by the respective hydrologic boundaries. (Woodard-USGS)