Pollutants from industrial spills, farming, gasoline and chemical spills are much more likely to get into drinking water in western and southeastern Mower County.

Friday, March 15, 2002

Pollutants from industrial spills, farming, gasoline and chemical spills are much more likely to get into drinking water in western and southeastern Mower County.

According to a four-year study done by the Department of Natural Resources (DNR), those areas of Mower County are geologically sensitive because of thinner soil cover over bedrock, numerous sinkholes and faulting.

Project hydrogeologist with the DNR Moira Campion explained what that means. Those portions of the county, she said, are "particularly pollution sensitive because of the shallow till and faulting."

The till is the glacial deposit of sand that covers and protects the bedrock aquifers, which are the primary source of drinking water.

Campion said the thickest till is in the center of the county and has the most significant influence on ground water. The thicker till in that area prevents water at the lands surface from rapidly infiltrating bedrock aquifers.

The four-year study produced two maps of Mower County, the County Geologic Atlas Part A and B.

Part A gives the data base, bedrock geology, surficial geology, topography and depth to the pre-cretaceous bedrock surface, subsurface stratigraphy and sand, gravel and bedrock resources.

Part B includes maps of hydrogeology, karst features and sensitivity to ground water pollution.

DNR regional ground water specialist Jeff Green said there is much faulting around the Austin area. Faulting also allows ground water to more rapidly move into the drinking water system.

Another feature of the land in Mower County that allows ground water to reach the aquifers rapidly, he said, are the sinkholes.

Green said, "Approximately 300 sinkholes were mapped in the county. Most of them occur in the LeRoy area and can range from a foot deep and 100 ft. wide to some that are 20 ft. deep and funnel shaped."

The purpose of the survey is to provide information for planning and protection of environmental resources such as well sealing programs and source water protection.

The survey will also give information affecting permit applications, land management planning and aid with planning in response to contaminant releases.

Maps and survey information are now available tot he public through the Minnesota Geologic Survey Atlas Survey Office (612) 627-4780 or through the DNR Waters at (651) 296-4800.

Another feature of the land in Mower County that allows ground water to reach the aquifers rapidly, he said, are the sinkholes.

Green said, "Approximately 300 sinkholes were mapped in the county. Most of them occur in the LeRoy area and can range from a foot deep and 100 ft. wide to some that are 20 ft. deep and funnel shaped."

The purpose of the survey is to provide information for planning and protection of environmental resources such as well sealing programs and source water protection.

The survey will also give information affecting permit applications, land management planning and aid with planning in response to contaminant releases.

Maps and survey information are now available tot he public through the Minnesota Geologic Survey Atlas Survey Office (612) 627-4780 or through the DNR Waters at (651) 296-4800.

Call Ailene Dawson at 434-2235 or e-mail her at ailene.dawson@austindailyherald.com