Water used in the Indianapolis area comes from two sources: the White River and tributary streams and the underground reservoirs formed by the underlying glacial drift and limestone. Surface-water sources provide about 60 mgd (million gallons per day) for public supply and an additional 300 mgd is used by private industries and is returned directly to the streams. About 60 mgd is taken from ground-water sources by public water supplies and industries. The total use of water, therefore, is about 420 mgd.

The city of Indianapolis and several adjacent urban communities are supplied through the surface-water sources by a private water company, the Indianapolis Water Co. Water is impounded in the Geist Reservoir on Fall Creek. At Broad Ripple, on White River, a low dam is used to divert river water into a feeder canal to a treatment plant. Expansion of the present facilities of this company is in progress. A new reservoir with a capacity about equal to that of Geist Reservoir is being constructed on Cicero Creek, a tributary of the White River. These combined river sources will provide an abundant supply of good water in excess of present demands. This will permit expansion of surface-water use for public, commercial, and industrial supply in the service area of this water company.

Industry is the heaviest user of ground water in the area. Of the 56 mgd of ground water pumped in 1952 about 70 percent was used by industry. Agriculture was next with a pumpage of about 15 percent and the remainder or 15· percent was for public and private water supply. The ground water is of relatively uniform composition and temperature.

Difficulties in supplying water have occurred and will continue to occur from time to time when demands on ground-water sources are excessively heavy for long periods of time and locally where pumped wells are too closely spaced. Under such conditions ground-water levels decline rapidly and remain depressed for some time. Such a condition may constitute what could be called a water shortage. As the demand for water increases there is need for conservation and wise use of available surface and ground-water supplies.