The Future of Water Reservoir Projects in Illinois and Their Relationship to Geologic Data

Abstract

The underground water resources of northeastern Illinois are perhaps better known than in any other part of the State, due to the intensive industrial development which has gone on there. The water horizons in this part of the State belong to the lower part of our State's geologic column. They include the Niagaran dolomite, Galena-Trenton series, St. Peter sandstone, Prairie du Chien series, and Potsdam sandstone. The depth to the Potsdam sandstone ranges from about 550 feet in Winnebago County to about 1400 feet at Chicago, and the depths to the other successively higher horizons are correspondingly less.8 Ordinarily, most of these aquifers furnish abundant supplies, but the excessive requirements in the vicinity of Chicago are a tax on nature to supply the water as rapidly as it is used, and as a result the static head is rapidly lowering. This fact has been brought out clearly by Mr. C. B. Anderson in the publication just referred to in the footnote, and with added force by Mr. Isham Randolph in his series of two articles which appeared in the Chicago Daily News, September 12 and 13, 1923. The proximity, however, of this territory to one of nature's largest fresh water reservoirs, Lake Michigan, reduces the apprehension which might otherwise attend this problem, but it is not true in the case of central and southern Illinois, where several municipalities have now reached a critical situation with regard to their water supply. In central and southern Illinois many of the county seats and larger towns have heretofore drawn their water supplies from the