DC groundwater sampling report: nitrate and PFAS detected across the county
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By LeAnn R. Ralph
MENOMONIE — The 2023 Dunn County water sampling project focused on a variety of contaminants in groundwater, including PFAS, which was detected in 14 of the 22 townships, and nitrate, which was present in all townships.
The Dunn County Planning, Resources and Development Committee reviewed the report on the groundwater study at the February 7 meeting.
The report shows that higher nitrate contamination is concentrated in southeastern Dunn County and that PFAS is present throughout much of the county, although at lower levels than the amount set by the Wisconsin Department of Health Services, and lower even than the new lower levels proposed by the United States Environmental Protection Agency.
Nearly 1,000 well water samples were collected and tested in Dunn County during the summer of 2023, and the program had good participation across the county, the report notes.
Samples were collected from all 22 townships in Dunn County:
• Town of New Haven — 28 samples.
• Town of Sheridan — 17 samples.
• Town of Wilson — 16 samples.
• Town of Sand Creek — 9 samples.
• Town of Tiffany — 18 samples.
• Village of Downing — 7 samples.
• Village of Boyceville — 1 sample.
• Town of Hay River — 26 samples.
• Town of Otter Creek — 25 samples.
• Town of Grant — 28 samples.
• Town of Stanton — 32 samples.
• Town of Sherman — 35 samples.
• Town of Tainter — 141 samples.
• Town of Colfax — 52 samples.
• Town of Lucas — 28 samples.
• City of Menomonie — 19 samples.
• Town of Menomonie — 135 samples.
• Town of Red Cedar — 111 samples.
• Town of Elk Mound — 48 samples.
• Village of Elk Mound — 2 samples.
• Town of Weston — 10 samples.
• Town of Dunn — 63 samples.
• Town of Spring Brook — 35 samples.
• Town of Eau Galle — 14 samples.
• Town of Peru — 27 samples.
• Town of Rock Creek — 42 samples.
Nitrate
Nitrate in the groundwater can come from fertilizers, animal waste, septic systems and other organic materials, according to the report.
The standard set by the EPA for safe drinking water is nitrate at 10 mg/L or less.
One health impact associated with high concentrations of nitrate in the water is methemoglobinemia (blue baby syndrome), which especially impacts infants under six months of age.
Some research has suggested other health problems could be linked to a high level of nitrate in the drinking water, such as elevated heart rate, headaches, and an increased risk for certain cancers, especially gastric cancer, according to the report.
Infants under six months of age and pregnant women should not consume water that has a nitrate concentration above 10 mg/L, and everyone should avoid long-term consumption of water that contains a nitrate level above 10 mg/L.
The report notes that across Dunn County, the average nitrate concentration is 4.42 mg/L.
The Towns of Spring Brook and Peru had average nitrate concentrations above 8 mg/L.
The Towns of Stanton and Grant both had average nitrate concentrations less than 2 mg/L.
Out of the nearly 1,000 samples, individual samples had concentrations of nitrate ranging from undetectable up to 40.4 mg/L, while 114 samples, or 11.7 percent, tested above the health standard of 10 mg/L, according to the report.
Here are the average concentration of nitrate by township:
• Town of New Haven — 3.11 mg/L.
• Town of Sheridan — 3.36 mg/L.
• Town of Wilson — 4.31 mg/L.
• Town of Sand Creek — 3.56 mg/L.
• Town of Tiffany — 2.12 mg/L.
• Town of Hay River — 5.8 mg/L.
• Town of Otter Creek — 2.2 mg/L.
• Town of Grant — 1.76 mg/L.
• Village of Downing — 1.53 mg/L.
• Village of Boyceville — 1.4 mg/L.
• Town of Stanton — 1.99 mg/L.
• Town of Sherman — 2.93 mg/L.
• Town of Tainter — 3.87 mg/L.
• Town of Colfax — 4.08 mg/L.
• Town of Lucas — 3.98 mg/L.
• Town of Menomonie — 3.33 mg/L.
• City of Menomonie — 3.61 mg/L.
• Town of Red Cedar — 5.58 mg/L.
• Town of Elk Mound — 4.11 mg/L.
• Village of Elk Mound — 4.45 mg/L.
• Town of Weston — 2.54 mg/L.
• Town of Dunn — 7.24 mg/L.
• Town of Spring Brook — 8.15 mg/L.
• Town of Eau Galle — 5.24 mg/L.
• Town of Peru — 8.39 mg/L.
• Town of Rock Creek — 7.06 mg/L.
Over 10 mg/L
A number of townships had wells that tested above 10 mg/L for nitrate:
• Town of Colfax — 3 samples over 10 mg/L out of 52 samples total.
• Town of Dunn — 20 samples over 10 mg/L out of 63 samples total.
• Town of Eau Galle — 2 samples over 10 mg/L out of 14 samples total.
• Town of Elk Mound — 4 samples over 10 mg/L out of 48 samples total.
• Town of Hay River — 6 samples over 10 mg/L out of 26 samples total.
• Town of Lucas — 3 samples over 10 mg/L out of 28 samples total.
• Town of Menomonie — 4 samples over 10 mg/L out of 136 samples total.
• City of Menomonie — 1 sample over 10 mg/L out of 19 samples total.
• Town of Peru — 8 samples over 10 mg/L out of 27 samples total.
• Town of Red Cedar — 21 samples over 10 mg/L out of 111 samples total.
• Town of Rock Creek — 10 samples over 10 mg/L out of 42 samples total.
• Town of Sand Creek — 2 samples over 10 mg/L out of 9 samples total.
• Town of Sherman — 1 sample over 10 mg/L out of 35 samples total.
• Town of Spring Brook — 10 samples over 10 mg/L out of 35 samples total.
• Town of Stanton — 1 sample over 10 mg/L out of 32 samples total.
• Town of Tainter — 16 samples over 10 mg/L out of 141 samples total.
• Town of Wilson — 2 samples over 10 mg/L out of 16 samples total.
Residents with nitrate levels above 10 mg/L are advised to consider corrective actions that can be taken, such as using alternative sources for the water used for eating and drinking (bottled water), drilling a deeper well, or treatment systems with reverse osmosis or distillation, according to the report.
Other parameters
Other parameters that were included in the testing were the saturation index (corrosivity and scale-forming ability of the water); total hardness; alkalinity; conductivity (how well a water sample can carry electrical current); pH (measure of how acidic the water is) and chloride.
Water samples also were tested for arsenic, calcium, copper, iron, lead, magnesium, manganese, phosphorus, potassium, sodium, sulfate, and zinc.
DACT screen
The water sampling also conducted a test for diaminochloroctriazine or DACT, which is a compound created when certain pesticides break down.
Consuming water that contains a concentration of DACT above 3.0 micrograms per liter [ug/L] is not recommended.
Out of the nearly 1,000 samples collected, 40 of them had detectable levels of DACT, but the highest sample had a concentration of .82 ug/L, which is well below the recommendation of 3.0 ug/L.
Half of the water samples with detectable DACT were found in the Towns of Red Cedar and Dunn, but all of the samples were well below the safe drinking water standard.
PFAS
PFAS is a group of chemicals known as “forever chemicals” that are a concern in groundwater.
The compounds are used in firefighting foams, nonstick cookware, stain resistant carpeting, fabric softeners, cosmetics and even in toilet paper, according to the report.
The compounds are stable and travel easily through the environment.
The current drinking water standard for PFAS is 70 parts per trillion (ppt).
The EPA is working to lower the limit to 6 ppt.
PFAS has been linked to decreased fertility in women, developmental delays in children, thyroid disease and increased cholesterol levels, the report states.
The Wisconsin State Laboratory of Hygiene tested for 33 different PFAS compounds in the water samples collected in Dunn County, which includes the 18 compounds listed in the safe drinking water standard.
Out of the 22 townships in Dunn County, water samples from 14 townships had detectable levels of PFAS.
The level of PFAS in all of the samples were below the standard set by the Wisconsin Department of Health Services and were lower than the standard of 6 ppt currently being proposed by the EPA.
PFAS was absent in the water samples from the Towns of Wilson, Sand Creek, Hay River, Tainter, Colfax, Menomonie, Dunn and Rock Creek.
Detectable levels of PFAS were in water samples from New Haven, Sheridan, Tiffany, Otter Creek, Grant, Stanton, Sherman, Lucas, Red Cedar, Elk Mound, Weston, Spring Brook, Eau Galle and Peru.
Again, the levels of PFAS detected were lower than the current drinking water standards, and were even lower than the lower standard of 6 ppt currently being proposed by the EPA.
