Dunn County staff report 14% of private well samples high in nitrates as in-house testing expands

A county conservation staff member told the Dunn County Planning, Resource and Development Committee on March 18 that the county’s groundwater-sampling program has shifted to in-house nitrate testing and that about 13.5–14% of samples returned high nitrate results in the most recent cycle. The program, staff said, was started with ARPA funding and later received EPA support.

The staff member said the Dunn County Health Department Water Lab now processes samples, which reduced costs and logistical delays compared with outsourcing. "The Dunn County Health Department Water Lab is processing all of our samples," the staff member said, adding that in-house testing also lets staff verify suspicious results quickly by re-sampling.

Why it matters: an estimated half of Dunn County households rely on private wells, which do not have the same regulatory testing requirements as municipal systems. High nitrate levels can pose health risks, particularly for infants and pregnant people, and local officials said monitoring helps target outreach and follow-up testing.

The presentation summarized geographic patterns and program logistics. The staff member said Tainter, Menominee and Red Cedar townships showed the largest participant numbers and that Springbrook and Rock Creek routinely return higher rates of elevated nitrate. "Last year we had about 14% of the samples came back high," the staff member said, noting one well returned values "in the forties" and prompted an immediate re-test by the county lab.

Program goals, the staff member said, are primarily education and long-term monitoring at repeat sites so the county can observe trends as land use and precipitation patterns change. "By looking at the same wells each year, we can see, is there something happening? Is this changing?" the staff member said.

Staff described current recruitment and funding: roughly 100 residents were on the participant list at the time of the presentation and the program aims to recruit 300 samples for the year. Initial funding came from ARPA; EPA funding in 2024 and 2025 helped expand and sustain the effort. The presenter said staff expects, with current funding and cost controls, to sustain the program through about 2028–29 unless additional grants are secured.

Committee members asked about cost and lab comparisons; the staff member said the county lab’s nitrate testing is on par with other public labs and that the main savings are in staff time and travel. The committee also discussed possible targeted sampling near planned long-term land uses such as solar installations.

Next steps: staff will continue recruitment for the current year, prioritize repeat sampling sites to monitor trends, and pursue additional grants to sustain the program beyond 2028. The committee did not vote on a new policy at the March 18 meeting.