An analysis of the ground-water resources of the Hamilton and Tipton Counties was based on data from about 1,900 well logs, 125 water levels in 125 wells, streamflow measurements at 57 sites, and municipal- and industrial-pumpage records. These data were used to map the flow system and construct a three-dimensional model of the study area and a more detailed two-dimensional model of the outwash deposits along the White River. The models were used to determine the pumpage from several pumping plans and the effect of these pump-ages on streamflow and ground-water levels.

Model results indicate that 39 million gallons per day could be obtained from the outwash aquifer. This quantity of pumping in areas of high transmissivity near and parallel to the White River would reduce the saturated thick-ness of the aquifers at the wells by half. The models also indicated that 0.18 to 6.7 million gallons per day could be pumped from the confined sand and gravel and the bedrock aquifers that have high transmissivities and are near favor-able discharge areas.

Drift covers most of the study area and ranges in thickness from 0 to about 400 feet. The drift consists mainly of till and outwash deposits. Beneath the drift lie Silurian and Devonian limestone, dolomite, and shale having a surface relief of about 300 feet.

The study area contains five discontinuous, confined sand and gravel aquifers within the till, an outwash aquifer associated with the White River, and a bedrock aquifer. Of these aquifers, the south half of the outwash aquifer, having a saturated thickness averaging 70 feet and a width ranging from 2 to 3 miles, has the greatest potential for water supply. The general ranges of measurements for the aquifers are: thin and discontinuous confined aquifer, thickness from 5 to 20 feet and transmissivity from 1,000 to 20,000 square feet per day; outwash, transmissivity from 1,000 to 28,000 square feet per day; and bedrock, transmissivity from 500 to 10,000 square feet per day. Vertical hydraulic conductivity of the confining beds between the confined aquifers ranges from 7 x 10-4 to 7 x 10-2 feet per day and averages near 7 x 10-3 feet per day.