Well sampling planned in Cook, Yellow Medicine counties for groundwater atlases

The Minnesota Department of Natural Resources will collect water samples from about 90 wells in Cook and Yellow Medicine counties this summer and fall to develop their official groundwater atlases.

The process involves collecting a water sample from an outside spigot or hydrant for laboratory analysis. The DNR then analyzes the sample for dozens of water components to determine the chemistry of local aquifers. Participation is voluntary, and owners will receive a report of their individual laboratory results at no cost. While sampled locations will appear on atlas maps, the report won’t include contact and ownership information.

The DNR will contact a selection of well owners by mail to request permission to sample their wells. Wells are chosen based on geology, location, well depth and well construction. The information gathered helps hydrologists create county maps and descriptions of groundwater distribution, movement, conditions, and aquifer pollution sensitivity. The atlas and maps will be printed and shared online, and geographic information system files will be available for download and use.

The groundwater atlases help:

• Identify viable drinking water sources
• Support sustainability
• Guide well and septic system construction decisions
• Inform well-head protection efforts for public water supplies
• Highlight regional recharge and groundwater movement
• Assess pollution sensitivity and possible contaminant migration

Each county atlas is Part B of a two-part series. The Minnesota Geological Survey produces the corresponding Part A atlases. The Geologic Atlas of Cook County, Minnesota was recently released and The Geologic Atlas of Yellow Medicine County, Minnesota was published in 2025.

A full description of the Groundwater Atlas program and completed atlas products are available on the DNR website.

Partial funding for the groundwater atlas project is provided by the Minnesota Environment and Natural Resources Trust Fund and Minnesota’s Legacy Clean Water Fund.