The County Road A disposal site, located on the Bad River Indian Reservation, Ashland County, Wisconsin, contains papermill sludge generated by a former mill in the City of Ashland. Since the time of disposal (1968-1970) the site has been the subject of investigations by the U.S. Bureau of Indian Affairs, the U.S. Environmental Protection Agency, and private consultants. During 1997- 1998, an investigation was conducted by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency and the Natural Resources Department of the Bad River Indian Tribe, to evaluate the hydrogeology and groundwater quality of the disposal site, particularly with respect to the hydraulic connection between two ponds at the site and the shallow ground-waterflow system. Additional monitoring wells and well points were installed, and additional hydrogeologic, ground-water quality, and geophysical data were collected. The data from this and previous studies were integrated and interpreted.