The report (1) describes the water-use data available from water-utility managers and water users in the Rockford and the Kankakee areas of Illinois during 1984, (2) presents an evaluation of the accuracy of these data, and (3) describes methods and water-use coefficients for estimating water use. The report contains data and estimates on water withdrawal, delivery, consumptive use, release, return, and conveyance loss and gain for six communities served by the public-water systems of the Rockford and the Kankakee areas. The water-use categories studied were commercial, industrial, domestic, and municipal uses; public supply; and sewage treatment. Water-use information for the first four categories is limited to water users that receive water from a public-water supplier and (or) release water to a sewage-treatment plant in the Rockford and the Kankakee areas.