Dunn County continues well-monitoring push; ad hoc groundwater recommendations advance

Dunn County staff reported continued private-well testing and follow-up planning Wednesday, saying the county aims to repeat a roughly 300-well monitoring effort this year and use repeat samples to analyze trends.

The update matters because county staff and the Groundwater Ad Hoc Committee are compiling the data needed to spot long-term changes in nitrate levels and to inform comprehensive planning, land-management decisions and homeowner outreach.

Land and Water staff said the county sampled about 300 private wells last summer and expects to target 300 again this year. "We collected 263," a staff member said, adding that the county partnered with the Department of Agriculture, Trade and Consumer Protection (DATCP) and that DATCP collected additional samples in areas considered more susceptible to contamination. Staff also said the county will now use its local health department lab to process nitrate samples rather than shipping bottles to a private lab out of Stevens Point.

County staff described the monitoring program as having two parallel goals: building a multi-year data set suitable for trend analysis and expanding public education so more residents test their wells and understand results. "We're shooting for 300 wells again this year. Right now, as of this morning, I have 107 folks signed up," the staff member said, describing recruitment via social media and help from municipal clerks.

Staff explained why multi-year, repeat sampling matters for interpretation: seasonal variation changes nitrate concentrations, so samples collected in different months cannot be directly compared. The presenter said meaningful trend signals generally become clearer after about five years of repeat sampling at the same wells.

The committee also reviewed the Groundwater Ad Hoc Committee progress report. Staff noted several recommendations are in active use (marked green in the committee report), including work on grazing projects with producer-led watershed groups, the upcoming comprehensive-plan update and other longer-term initiatives. "A lot of the work that we are engaged with right now seems to fit within many of these recommendations," a committee member said.

Committee members discussed citation authority contained in the county's ag performance and manure storage ordinance. Staff explained the ordinance includes a citation tool but the county has not developed procedures to use it. "Citations are not our preferred or go-to method to achieve compliance," a staff member said, noting the county prefers cooperative approaches and cost-share offers but that the DNR has sometimes used citations in recent runoff enforcement cases.

Committee members agreed citation authority should remain on the Ad Hoc list for future consideration but is not a current priority. Staff said citation use would likely be a tool of last resort and recommended clarifying the ordinance in the future so it reflects whether citation authority will be implemented.

The report also noted the county's recent and planned public events: the Red Cedar Watershed Conference (about 204 attendees) and upcoming town-hall style outreach tied to the monitoring program and the comprehensive-plan engagement process.

Committee members asked staff to continue regular updates on sampling counts, trends and data uploads to the county groundwater viewer. Staff said 2023 monitoring results have been submitted for upload but they will confirm with the land information office that the data are posted; pesticide testing collected by DATCP will not be uploaded in full because of the size and complexity of those data.

Staff said additional grant funding would allow continued testing. The committee flagged education and trend analysis as important near-term deliverables and recommended keeping the monitoring program and the Groundwater Ad Hoc recommendations under active review.