From an article by Chad Dally in the Wausau Daily Herald:

Wisconsin scientists hope to drill a well in Marathon County to determine the potential of using the earth’s own heat to power homes and produce renewable energy.

The Wisconsin Geological and Natural History Survey in October asked for permission to drill a geothermal well in one of three spots in the county: Mission Lake County Park, the Ringle Forest Unit and Leather Camp Forest Unit.

Those spots were chosen because the geology shows extensive granite deposits, which tends to hold more heat than other forms of rock such as sandstone or dolomite, said David Hart, the Geological and Natural History Survey’s project manager.

The county’s Forestry and Recreation Committee this week approved the request and opted for the Leather Camp site south of Kronenwetter because drilling there would have the least effect on recreation opportunities. The Environmental Resources Committee also will consider the request April 19.

If approved, the research well would be 6 inches in diameter and between 800 and 1,000 feet deep in Leather Camp forest, Hart said. There is limited information about Wisconsin’s geothermal resources, and the Marathon County well is one of six planned to assess potential.

Researchers would measure how the temperature increases with depth.

“I view our study as basic measurements necessary to decide whether or not we should pursue enhanced geothermal energy in Wisconsin,” Hart said. “The study will also benefit the heat pump or groundsource geothermal systems that many homeowners are installing.”