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Home > Protecting Our Lands & Waters > Clean Water Fund > Groundwater & Drinking Water Protection > Characterizing Nitrates in Private Drinking Water Wells

Characterizing Nitrates in Private Drinking Water Wells

Locally-led Projects to Protect Groundwater

Central Sands Private Well Network for Nitrate 2015 Results (PDF: 776 KB / 2 pages)

Central Sands Summary 2014 (PDF: 447 KB / 2 pages)

Central Sands Summary 2013 (PDF: 427 KB / 2 pages)

Central Sands Summary 2012 (PDF 517 KB / 2 pages)

Central Sands Summary Report 2011 (PDF 834 KB / 16 pages)

Central Sands Private Well Network - 2011 Appendix 1 (PDF 483 KB / 16 pages)

Boy drinking a glass of waterAn overview:

  • All counties in the Central Sands region have been invited to participate in a county-wide private well network.
  • Nitrate analysis of 1,555 private wells was completed.
  • A subset of participating  homeowners (555) will be used to establish a long-term monitoring network.  
  • Goal of Phase 1: Determine current nitrate concentrations in private wells throughout the Central Sands region of Minnesota.
  • Goal of Phase 2: Determine areas of concern and develop a long-term nitrate trend monitoring network.
  • A monitoring network will provide a better understanding of nitrate trends in the region and be used to educate private well owners about the quality of their drinking water. This project will help answer the question: Are nitrate concentrations in private drinking water wells increasing, decreasing or staying the same?

Which counties are located in the Central Sands region?

Becker, Benton, Cass, Crow Lake, Douglas, Hubbard, Kandiyohi, Morrison, Otter Tail, Pope, Sherburne, Stearns, Todd, Wadena 

 Minnesota counties in the Central Sands region, dots indicate the locations of individual wells that are part of the monitoring network

Private Well Monitoring

The monitoring network is distributed across 14 counties. Selection of individual wells was random, and results from this program can be used to make conclusions about nitrate trends in drinking water across the region. 

When a well owner agreed to participate, they filled out a survey about their well (construction type, well depth, age, etc) and returned it. Each participant received a sample kit from a certified lab with instructions on how to take the sample and where to send it for analysis.

Summary of 2011 Results: Read the 2011 Summary Report (PDF: 635 KB / 16 pages) to learn more!

  • A total of 1,555 well owners returned their well survey and water samples for analysis.
  • Over 88.6% of the wells sampled had nitrate concentrations less than 3 mg/L, 6.8% of the wells ranged from 3-10 mg/L of nitrate and 4.6%were greater than the drinking water standard of 10 mg/L.
  • Nitrate concentrations varied widely over short distances and there was significant local variability in nitrate concentrations.
  • Nitrate concentrations varied between counties. Morrison County had the highest percentage of wells (10.5%) with nitrate concentrations over 10 mg/L. Benton and Wadena County both had approximately 8% of wells over 10 mg/L. Cass, Crow Wing, and Douglas counties did not have any results above 10 mg/L.
  • Shallow wells (0-50 ft) comprise 46% of the results over 10 mg/L, while wells that are deeper (101-300 ft) only make up 7 %.
  • As nitrate concentrations increase the proportion of wells that are greater than 50 years old also increases from 7% to 26%. 

Why is this program focused on Nitrates?

Nitrate is a water soluble molecule that is made up of nitrogen and oxygen. It is naturally occurring in the environment; however at elevated levels it can have negative effects on human health. According to a 2007 Minnesota Pollution Control report, nitrate is one of most common contaminants in Minnesota's groundwater, and in some areas of the state a significant number of wells have high nitrate levels (Minnesota's Ground Water Condition: A Statewide View, MPCA 2007). The U.S. Environmental Protection Agency (USEPA) has established a drinking water Maximum Contaminant Level (MCL) of 10 mg/L for nitrate-nitrogen (U.S. EPA, 2009).

Although nitrate occurs naturally, it can also originate from man-made sources such as fertilizer, animal manure and human waste.

Regions of Minnesota most vulnerable to nitrate contamination are central and southeastern Minnesota. Central Minnesota counties are vulnerable because of widespread sandy soil and regions of southeast Minnesota are vulnerable because of shallow bedrock, sinkholes and underground caves (referred to as karst geology), which lead to exchanges between surface and ground water resources.  

Nitrate Water Testing Clinics

Between 1993 and 2006, the MDA operated "walk in" style water testing clinics with the goal of increasing public awareness about nitrates in rural drinking and livestock water supplies. The clinics offered free nitrate analysis and provided immediate results to homeowners.

This accurate, yet inexpensive water testing procedure has provided nitrate analysis and educational outreach to over 50,000 well owners.

The MDA has trained many local partners to operate nitrate testing clinics. Equipment and training are available for any community that would like to offer testing services. This procedure is adaptable for county fairs, field day events, public school programs, and "stand alone" events.

In 2011, the MDA helped 40 Local Government Units host nitrate testing clinics. A total of 2,100 water samples were tested. This information will be updated soon to reflect plans for the summer of 2013.

County Partners: Becker, Benton, Cass, Crow, Douglas, Hubbard, Kandiyohi, Morrison, Otter Tail, Pope, Sherburne, Stearns, Todd, Wadena
**Wadena County Soil and Water Conservation District is the lead local project coordinator.

Additional Partners: Minnesota Center for Survey Research, RMB Environmental Laboratories, Inc.

 MDA Contacts

Kimberly Kaiser
Hydrologist 2
Kimberly.Kaiser@state.mn.us ~ 651-201-6280

Bruce Montgomery
Fertilizer Unit Supervisor
Bruce.Montgomery@state.mn.us ~ 651-201-6178