Horizontal and vertical hydraulic conductivity of the Streambed were estimated from results of hydraulic tests along four transects across the east branch Grand Calumet River in northern Lake County, Indiana. Tests were done in two types of temporary wells installed in the Streambed 2-inch-diameter wells that had a 1- or 2-foot length of wire-wrapped screen and 3-inch-diameter wells that were open at the ends. When possible, the hydraulic tests included monitoring both falling- and rising-water levels. A total of 47 tests for horizontal hydraulic conductivity and 20 tests for vertical hydraulic conductivity were done.

Data collected during the tests were analyzed by use of methods developed by earlier investigators. Horizontal hydraulic conductivity of the streambed was varied and ranged from 1.Ox1O^-2 to 1.2x1O⁺³ feet per day. Compared to the previously reported range of horizontal hydraulic conductivity for the Calumet aquifer, 6.5X10^-1 to 3.6x1O⁺² feet per day, results of 24 hydraulic tests in the streambed of the east branch Grand Calumet River were within the reported range, 18 were less than the lowest reported value, and 5 were greater than the highest reported value.

Vertical hydraulic conductivity of the streambed was less varied than horizontal hydraulic conductivity and ranged from 3.Ox1O^-1 to 7.3x1O⁺¹ feet per day. The ratio between horizontal and vertical hydraulic conductivity calculated for each transect ranged from 1:0.09 to 1:8.5.

The hydraulic conductivity of the streambed generally was dependant on the type of sediments in the part of the streambed that was tested. Although most of the streambed contained soft, fine-grained sediments, parts of the streambed also contained fill materials including coal, cinders, and concrete and asphalt rubble. The highest values of horizontal hydraulic conductivity generally were calculated from data collected at locations where the streambed contained fill materials, particularly concrete and asphalt rubble. Horizontal hydraulic conductivities determined for 11 hydraulic tests in predominantly fill materials ranged from 1.2x1O⁺¹ to 1.2x1O⁺³ feet per day and averaged 5.6x1O⁺² feet per day. The lowest values of horizontal hydraulic conductivity were calculated from data collected at locations where the streambed contained fine-grained sediments. Horizontal hydraulic conductivities determined for 36 hydraulic tests in predominantly fine-grained sediments ranged from 1.Ox1O^-2 to 2.4x1O⁺² feet per day and averaged 1.5x1O⁺¹ feet per day.