Minnesota Private Well Water Risk: Arsenic & Nitrate

These figures are USGS statistical estimates for private (domestic) wells in Minnesota. They describe the area's modeled risk — not any single well.

This is a modeled probability for the area, not a measurement of your well. USGS statistical models estimate how many private wells in this area are likely to exceed the federal limit — they cannot tell you what is in your water. Two neighbors can have very different results. The only way to know your well is to test it.

Nitrate

0%

of the private-well population is modeled above the 10 mg/L nitrate limit

~441

people on wells estimated above the limit

~1,110,000

total residents on private wells statewide

Source: USGS machine-learning nitrate model, Ransom et al. (2022), domestic-well depth zone.

Arsenic

Across Minnesota, an estimated ~80,354 people rely on private wells with modeled arsenic above the 10 µg/L EPA limit. The highest modeled exposure is in Blue Earth County (~4,305 people).

Counties with the highest modeled arsenic exposure

CountyEst. well residents over arsenic limit90% range
Blue Earth County~4,3053,440–5,295
St. Louis County~3,5982,942–4,425
Anoka County~2,9832,310–3,858
Crow Wing County~2,6571,973–3,570
Nicollet County~2,2481,768–2,770
Sibley County~2,1931,747–2,682
Sherburne County~2,1911,701–2,799
Otter Tail County~1,9091,478–2,480
Wright County~1,8771,490–2,384
Redwood County~1,8651,543–2,214
Beltrami County~1,8271,392–2,396
Brown County~1,7641,448–2,100
Itasca County~1,6511,311–2,088
Freeborn County~1,6371,267–2,084
Washington County~1,5611,189–2,062
Le Sueur County~1,5471,226–1,939
Faribault County~1,4641,160–1,788
Waseca County~1,4341,130–1,792
McLeod County~1,4061,191–1,662
Benton County~1,3761,092–1,727
Cass County~1,3581,035–1,794
Chisago County~1,3531,052–1,745
Isanti County~1,3461,064–1,700
Jackson County~1,3371,067–1,641
Pine County~1,3281,099–1,609
Polk County~1,3121,099–1,559
Rice County~1,2771,070–1,531
Mille Lacs County~1,266992–1,625
Todd County~1,2631,005–1,582
Douglas County~1,252958–1,643
Stearns County~1,218980–1,522
Roseau County~1,190960–1,464
Martin County~1,185954–1,455
Morrison County~1,176933–1,487
Kandiyohi County~1,166948–1,443
Becker County~1,131879–1,465
Meeker County~1,095916–1,314
Aitkin County~1,054824–1,356
Carlton County~1,028853–1,246
Renville County~982817–1,170
Kanabec County~893746–1,073
Hubbard County~881677–1,152
Scott County~881740–1,050
Steele County~849688–1,045
Mower County~805664–977
Watonwan County~684572–813
Pennington County~629518–758
Lyon County~624538–723
Goodhue County~540424–691
Clay County~512417–627
Dodge County~419351–499
Carver County~408340–491
Murray County~401344–469
Clearwater County~387315–475
Lac qui Parle County~387329–455
Olmsted County~364294–454
Wadena County~352276–448
Pope County~334272–413
Lake of the Woods County~319252–403
Koochiching County~269216–335
Norman County~248204–300
Winona County~243182–322
Nobles County~240198–290
Marshall County~224183–273
Chippewa County~221188–260
Wabasha County~220165–295
Dakota County~219176–275
Fillmore County~202164–249
Mahnomen County~202167–245
Lake County~192162–231
Stevens County~187155–226
Wilkin County~176143–215
Swift County~176148–209
Red Lake County~163135–194
Houston County~157120–206
Grant County~129106–157
Big Stone County~120102–142
Traverse County~11796–144

9 additional Minnesota counties have lower modeled arsenic exposure (fewer than 100 estimated well residents over the limit).

Source: USGS domestic-well arsenic model, Lombard et al. (2021); county population product (2017).

Treating arsenic in Minnesota

Arsenic is not removed by carbon pitchers or faucet filters. Reverse osmosis is the treatment that brings it below the federal limit at your tap.

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