An aquifer test was made in the glacial-outwash aquifer along the course of the White River in Marion County, Ind., to establish the hydraulic characteristics of this unit and the hydraulic conductivity of the White River streambed at a site 11 kilometers south of the center of downtown Indianapolis. In the immediate vicinity of the site, at a depth of about 15 meters below land surface, a clay lens separates the outwash aquifer into an upper sand and gravel unit 12 m thick and a lower unit 8.5 m thick. At the site of the test well, the clay lens is 3.0 m thick. The test was made in the upper sand and gravel unit, and data were analyzed for an assumed condition of no, or at least negligible, transient leakage from the clay lens underlying this unit. As no observation wells were installed in the clay lens, this assumption cannot be directly substantiated. However, observation wells beneath the clay lens indicated that a head loss was not induced below the clay lens by the test well, and the closeness of the values obtained for transmissivity of the upper unit by three different methods strongly supports the assumption. Results of the test include for the upper unit: lateral hydraulic conductivity, 108 meters per day; range of transmissivity (determined by three techniques), from 1400 to 1670 meters squared per day; specific yield, 0.08; and vertical hydraulic conductivity of the streambed, 2.2 m/d. These results should be of use in assessing the potential supply and in developing one of Indiana's major aquifer systems because a knowledge of aquifer characteristics is essential for proper design and spacing of wells.
