A HYDROGEOPHYSICAL STUDY OF THE FOX RIVER SOUTH OF WAUKESHA, WI

A geophysical study along the Fox River south of the city of Waukesha, Wisconsin is in progress to help determine hydrologic properties of the glacially derived near surface sediments. It is part of a larger study to determine the interaction between the groundwater and surface water. Electromagnetic induction (EM) lines using a Geonics EM-31MK2 have covered approximately 1.1 km of the river, and parts of the surrounding shoreline. Forty electrical resistivity tomography (ERT) lines have been measured in the immediate area west of the river, with two additional lines across the river. The ERT was completed using a GF instruments Ares profiling system. The EM studies in the river have located two areas of low electrical conductivity that suggest these areas are underlain by material of high hydraulic conductivity such as gravel and sand. The ERT surveys are correlated with nearby lithologic well logs and electrical well logs. The ERT surveys west of the river show dominantly east - west regions of higher electrical resistivity that may be preferential groundwater pathways providing a hydrologic connection between the river and the groundwater system.