The state Department of Agriculture, Trade and Consumer Protection on Wednesday (Jan. 6) announced plans to use airborne electromagnetic (AEM) technology to measure the soil depth to bedrock in areas of Northeast Wisconsin.

Knowing how deep the soil is before reaching bedrock is considered a key to understanding how to protect groundwater from potential pollutants that are applied on the surface.

The project focuses on counties with Silurian bedrock, which is composed of highly fractured dolomite that allows material to pass more easily to reach groundwater quickly.

According to a press release from DATCP, the effort is spearheaded by the U.S. Geological Survey (USGS), with collaboration from the Wisconsin Department of Natural Resources (DNR), the Wisconsin Geological and Natural History Survey (WGNHS), and DATCP.

The plan is for a low-flying helicopter to tow a magnetic sensor that will provide data about below-ground properties to update existing depth-to-bedrock maps.

“This project will update our maps and help landowners better understand how surface applications of certain materials can impact groundwater quality,” said Sara Walling, administrator of DATCP’s Division of Agricultural Resource Management. “Protecting Wisconsin’s groundwater is essential to public health and to the state’s economy. We all rely on clean groundwater for drinking, irrigating crops, watering livestock, and processing foods.”

Depending on weather and flight conditions, the survey is expected to begin in a few days, with the helicopter flying over areas of Kewaunee, Brown, Calumet, Door, Fond du Lac, Manitowoc and Sheboygan counties.

The plan is for the helicopter to fly in a grid pattern, with half-mile spacing between flight lines. A three-mile control line of on-the-ground measurements taken by WGNHS will be compared with the flight measurements to ensure data accuracy.

The goal of updating the depth-to-bedrock maps is to reduce the financial burden on private landowners to verify existing maps and produce data that will enhance the understanding of the bedrock under the area in order to improve groundwater quality, the news release said.

Results of the survey are expected to be made public once available.