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Homeowners who rely on private wells for their drinking water supply should test for nitrates on a regular basis. This year, Dodge County Environmental Services will be offering seasonal Free Nitrate Screening Clinics at the Dodge County Government Services Building, 721 N. Main St. Mantorville on the 2nd floor. The nitrate clinic will be from 8:30 a.m. to 4 p.m. on Oct. 24 and 25.

If you’d like to have your well water tested, this is how to take a water sample.

  1. Run water for 5 - 10 minutes
  2. Collect a cup (8 oz) of water from your well in a clean plastic/glass container
  3. Keep the sample cold
  4. Results will be available within 5 minutes of testing

Samples should be taken less than 24 hours before the nitrate screening event. Also, you may bring in more than one sample if you’d like to test your water before and after any installed distillators, reverse osmosis tanks, or other nitrate removal systems.

The results of the testing help state agencies, local governments and the public get a better understanding of what is affecting our groundwater.

Depending on the well’s location in the county, it may be more likely to have nitrates in the water. Results from previous tests taken since 2008 show that areas with shallow bedrock depth can be more susceptible to elevated nitrate levels. The study shows that the north and eastern portions of the county contain karst topography and have more exposed aquifers. The south and western portions of the county have more protected aquifers because of sandy glacial moraine deposits. Landscape features such as sinkholes and Decorah shale also may worsen contamination.

Besides the geology surrounding the well, there are other factors that contribute to nitrates in well water. For example, faulty septic systems, and spreading manure or applying fertilizer and pesticide to crops can contribute to the nitrate in aquifers.

For more information, visit or call Environmental Services at (507) 635-6273.