The total amount of water withdrawn in Illinois during 1990 was about 18,016 million gallons per day (Mgal/d). This amount was about 740 Mgal/d less than in 1988. The total water withdrawn for thermoelectric-power generation was about 15,170 Mgal/d; about 370 Mgal/d was consumptively used. About 936 Mgal/d, or 33 percent, of the total water withdrawn in Illinois during 1990 was ground water, excluding withdrawals for thermoelectric-power generation; about 1,911 Mgal/d of surface water was withdrawn and used, excluding withdrawals for thermoelectric-power generation. Seventy-four percent of the total surface water, excluding withdrawals for thermoelectric-power generation, was withdrawn by public-supply facilities. The next largest use of surface water was for self-supplied industrial withdrawals. Forty-seven percent of the total ground water was withdrawn by public-supply facilities. The next largest use of ground water was for irrigation. About 25 Mgal/d of the total ground water withdrawn was saline. Sixty-five percent of the total water withdrawn, excluding thermoelectric withdrawals, in Illinois during 1990 was for public-supply facilities. The next largest users of the total water withdrawn was for self-supplied withdrawals by industries and for irrigation. Water withdrawn and delivered from public-supply facilities in Illinois during 1990 totaled about 1,859 Mgal/d. Surface water and ground water were the sources for about 1,415 and 444 Mgal/d, respectively, of the withdrawals for public supply. The total water obtained from Lake Michigan for public-water supply was about 1,146 Mgal/d. About 115 Mgal/d was withdrawn for self-supplied domestic purposes. Total self-supplied withdrawals and deliveries from public-water facilities for commercial use were about 672 Mgal/d. About 173 Mgal/d was self- supplied by the commercial establishments. Total irrigation water withdrawals were about 78 Mgal/d. Total estimated livestock withdrawals were about 63 Mgal/d. Total self-supplied withdrawals and deliveries from public-supply facilities for industrial purposes were about 728 Mgal/d. About 464 Mgal/d was self-supplied withdrawals by industrial facilities. A total of about 94 Mgal/d was withdrawn during mining activities. A total of about 33 Mgal/d was withdrawn during mining from ground-water sources; about 25 Mgal/d of the ground water withdrawn was saline.