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Home > Protecting Our Lands & Waters > Clean Water Fund > Groundwater & Drinking Water Protection > Private Well Pesticide Sampling Project > Who, How, Why Participate

PWPS Participation


The Private Well Pesticide Sampling (PWPS) Project is a follow-up testing program to the Minnesota Department of Agriculture Township Testing Program.  Homeowners in a township are offered the opportunity to participate if their township has at least 30% of the area characterized with vulnerable groundwater and at least 20% of the area in crop production. 

Homeowners are offered a free follow-up pesticide test if nitrate is detected in their first township sample.    

County Participation

Counties and townships are selected using the techniques defined in the PWPS Project Work Plan (PDF: 255 KB / 11 pages).

Counties that have been sampled

2014-2015: Benton, Dakota, Morrison, Olmsted, Stearns, Sherburne, Wadena and Washington Counties

2016: Otter Tail, Pope, Sherburne and Morrison Counties

Counties currently in sampling process

 2017: Becker, Benton, Dodge, Douglas, Hubbard, Kandiyohi, Nobles, Rock, Todd and Winona Counties

Counties projected to be sampled

2018: Clay, Fillmore, Goodhue, Rice and Wabasha Counties

2019: Blue Earth, Brown, Carver, Chippewa, Chisago, Clearwater, Cottonwood, Faribault, Houston, Kanabec, La Sueur, Lincoln, Lyon, Meeker, Nicollet, Pipestone, Polk, Scott, Steele, and Wright Counties

2020: Big Stone, Freeborn, Lac Qui Parle, Mower, Redwood, Swift, Traverse, Waseca, Watonwan, and Yellow Medicine Counties



The information gained from this testing is valuable to the homeowner and Minnesota Department of Agriculture. The homeowner learns more about the current nitrate and pesticide conditions in their well. The Minnesota Department of Agriculture learns the localized nitrate and pesticide results to enable more informed local planning and decision-making to protect groundwater.

The Minnesota Department of Agriculture has evaluated the relationship between nitrate and pesticides in monitoring wells and in drinking water wells. In general, the probability of detecting pesticides in a well increases as nitrate concentration increases. When levels of nitrate are above 3 mg/L (ppm), there is a high likelihood that pesticides will be present. However, the relationship between nitrate and pesticide concentrations is less clear. Having a high concentration of nitrate in your water does not necessarily mean the pesticide concentration will also be high. It is also possible to have low, or no detectable nitrate in your water and still have pesticides present. Even though pesticide concentrations in groundwater rarely exceed drinking water standards in Minnesota, there are uncertainties about the health risks associated with consuming water that contains a mixture of pesticides and nitrate.

For more information: Analysis of Co-occurrence of Nitrate-Nitrogen and Pesticides in Minnesota Groundwater (PDF: 183 KB / 17 pages)


Man with safety goggles filling a glass sample bottle from an outside faucet on the side of a house.Homeowner Responsibilities to Participate

  • If you have been selected for testing, complete the PWPS Project consent form.
  • Allow MDA hydrologists on your property to collect pesticide and nitrate samples from your outside water faucets.
  • Participate in a homeowner survey about the well information and potential nitrate sources.

MDA Responsibilities

  • Provide supplemental funding for the program.
  • Assist with local coordination.
  • Collect samples according to protocol and submit to contracted laboratory for analysis.
  • Manage and organize results. 
  • Conduct statistical analysis and data summary.

PWPS Project Main Page
PWPS Project State Statute and Funding
PWPS Project Results

MDA Contact

Jeff Paddock
jeff.paddock@state.mn.us ~ 651-201-6560