Minnesota well water by county: arsenic and nitrate
Modelled arsenic and nitrate for private-well users in every Minnesota county, what to test for, and where to find a certified lab. Private wells aren’t covered by the Safe Drinking Water Act.
All 87 counties
- Anoka CountyWell users 51,700Arsenic about 2 in 100Nitrate 0.3 mg/L
- Stearns CountyWell users 51,500Arsenic about 7 in 100Nitrate 1.7 mg/L
- St. Louis CountyWell users 51,100Arsenic about 4 in 100Nitrate 0.0 mg/L
- Hennepin CountyWell users 42,500Arsenic about 6 in 100Nitrate 0.2 mg/L
- Wright CountyWell users 38,600Arsenic about 7 in 100Nitrate 0.6 mg/L
- Washington CountyWell users 37,700Arsenic about 3 in 100Nitrate 0.6 mg/L
- Crow Wing CountyWell users 32,800Arsenic about 2 in 100Nitrate 0.2 mg/L
- Otter Tail CountyWell users 32,400Arsenic about 15 in 100Nitrate 0.4 mg/L
- Sherburne CountyWell users 30,400Arsenic about 5 in 100Nitrate 1.1 mg/L
- Itasca CountyWell users 25,800Arsenic about 6 in 100Nitrate 0.2 mg/L
- Beltrami CountyWell users 25,600Arsenic about 4 in 100Nitrate 0.2 mg/L
- Dakota CountyWell users 24,800Arsenic about 3 in 100Nitrate 0.4 mg/L
- Chisago CountyWell users 24,200Arsenic about 3 in 100Nitrate 0.3 mg/L
- Cass CountyWell users 23,800Arsenic about 3 in 100Nitrate 0.2 mg/L
- Olmsted CountyWell users 22,300Arsenic about 3 in 100Nitrate 0.3 mg/L
- Isanti CountyWell users 21,500Arsenic about 4 in 100Nitrate 0.3 mg/L
- Morrison CountyWell users 20,800Arsenic about 5 in 100Nitrate 1.4 mg/L
- Pine CountyWell users 20,700Arsenic about 6 in 100Nitrate 0.1 mg/L
- Becker CountyWell users 20,600Arsenic about 11 in 100Nitrate 0.1 mg/L
- Scott CountyWell users 19,600Arsenic about 9 in 100Nitrate 0.1 mg/L
- Douglas CountyWell users 18,900Arsenic about 10 in 100Nitrate 0.5 mg/L
- Carlton CountyWell users 17,300Arsenic about 4 in 100Nitrate 0.1 mg/L
- Rice CountyWell users 17,200Arsenic about 13 in 100Nitrate 0.1 mg/L
- Todd CountyWell users 16,700Arsenic about 6 in 100Nitrate 1.3 mg/L
- Carver CountyWell users 16,100Arsenic about 23 in 100Nitrate 0.1 mg/L
- Winona CountyWell users 16,000Arsenic about 3 in 100Nitrate 0.2 mg/L
- Hubbard CountyWell users 15,900Arsenic about 3 in 100Nitrate 0.5 mg/L
- Goodhue CountyWell users 15,600Arsenic about 4 in 100Nitrate 0.2 mg/L
- Mille Lacs CountyWell users 15,000Arsenic about 6 in 100Nitrate 0.3 mg/L
- Kandiyohi CountyWell users 14,800Arsenic about 38 in 100Nitrate 0.1 mg/L
- Blue Earth CountyWell users 13,700Arsenic about 27 in 100Nitrate 0.0 mg/L
- Ramsey CountyWell users 13,200Arsenic about 4 in 100Nitrate 0.4 mg/L
- Benton CountyWell users 13,000Arsenic about 8 in 100Nitrate 0.8 mg/L
- Aitkin CountyWell users 12,900Arsenic about 3 in 100Nitrate 0.1 mg/L
- Kanabec CountyWell users 11,900Arsenic about 5 in 100Nitrate 0.3 mg/L
- Meeker CountyWell users 11,500Arsenic about 44 in 100Nitrate 0.1 mg/L
- McLeod CountyWell users 11,200Arsenic about 28 in 100Nitrate 0.0 mg/L
- Fillmore CountyWell users 9,900Arsenic about 5 in 100Nitrate 0.5 mg/L
- Le Sueur CountyWell users 9,900Arsenic about 27 in 100Nitrate 0.1 mg/L
- Mower CountyWell users 9,600Arsenic about 6 in 100Nitrate 0.0 mg/L
- Clay CountyWell users 9,200Arsenic about 17 in 100Nitrate 0.1 mg/L
- Freeborn CountyWell users 9,100Arsenic about 9 in 100Nitrate 0.0 mg/L
- Roseau CountyWell users 9,100Arsenic about 3 in 100Nitrate 0.0 mg/L
- Wabasha CountyWell users 8,900Arsenic about 4 in 100Nitrate 0.4 mg/L
- Polk CountyWell users 8,100Arsenic about 31 in 100Nitrate 0.1 mg/L
- Steele CountyWell users 7,800Arsenic about 13 in 100Nitrate 0.1 mg/L
- Houston CountyWell users 7,200Arsenic about 4 in 100Nitrate 0.3 mg/L
- Nicollet CountyWell users 7,200Arsenic about 19 in 100Nitrate 0.0 mg/L
- Wadena CountyWell users 7,000Arsenic about 5 in 100Nitrate 0.4 mg/L
- Dodge CountyWell users 6,800Arsenic about 8 in 100Nitrate 0.1 mg/L
- Sibley CountyWell users 6,700Arsenic about 27 in 100Nitrate 0.0 mg/L
- Pope CountyWell users 6,300Arsenic about 8 in 100Nitrate 0.4 mg/L
- Clearwater CountyWell users 6,300Arsenic about 7 in 100Nitrate 0.1 mg/L
- Waseca CountyWell users 5,800Arsenic about 15 in 100Nitrate 0.0 mg/L
- Brown CountyWell users 5,600Arsenic about 32 in 100Nitrate 0.0 mg/L
- Renville CountyWell users 5,500Arsenic about 33 in 100Nitrate 0.0 mg/L
- Martin CountyWell users 5,300Arsenic about 43 in 100Nitrate 0.0 mg/L
- Redwood CountyWell users 4,900Arsenic about 40 in 100Nitrate 0.1 mg/L
- Lyon CountyWell users 4,900Arsenic about 12 in 100Nitrate 0.1 mg/L
- Pennington CountyWell users 4,500Arsenic about 6 in 100Nitrate 0.0 mg/L
- Murray CountyWell users 4,500Arsenic about 17 in 100Nitrate 0.1 mg/L
- Faribault CountyWell users 4,400Arsenic about 23 in 100Nitrate 0.0 mg/L
- Nobles CountyWell users 4,200Arsenic about 8 in 100Nitrate 0.3 mg/L
- Jackson CountyWell users 4,000Arsenic about 41 in 100Nitrate 0.0 mg/L
- Cottonwood CountyWell users 4,000Arsenic about 32 in 100Nitrate 0.0 mg/L
- Yellow Medicine CountyWell users 4,000Arsenic about 18 in 100Nitrate 0.2 mg/L
- Swift CountyWell users 3,900Arsenic about 21 in 100Nitrate 0.2 mg/L
- Lake CountyWell users 3,800Arsenic about 3 in 100Nitrate 0.0 mg/L
- Chippewa CountyWell users 3,600Arsenic about 7 in 100Nitrate 0.2 mg/L
- Lac qui Parle CountyWell users 3,500Arsenic about 18 in 100Nitrate 0.1 mg/L
- Marshall CountyWell users 3,500Arsenic about 5 in 100Nitrate 0.0 mg/L
- Koochiching CountyWell users 3,300Arsenic about 4 in 100Nitrate 0.0 mg/L
- Watonwan CountyWell users 3,100Arsenic about 40 in 100Nitrate 0.0 mg/L
- Mahnomen CountyWell users 3,000Arsenic about 9 in 100Nitrate 0.0 mg/L
- Lake of the Woods CountyWell users 2,900Arsenic about 4 in 100Nitrate 0.0 mg/L
- Norman CountyWell users 2,800Arsenic about 9 in 100Nitrate 0.1 mg/L
- Stevens CountyWell users 2,700Arsenic about 5 in 100Nitrate 0.2 mg/L
- Grant CountyWell users 2,500Arsenic about 16 in 100Nitrate 0.1 mg/L
- Wilkin CountyWell users 2,400Arsenic about 11 in 100Nitrate 0.1 mg/L
- Cook CountyWell users 2,300Arsenic about 2 in 100Nitrate 0.0 mg/L
- Red Lake CountyWell users 1,900Arsenic about 6 in 100Nitrate 0.0 mg/L
- Rock CountyWell users 1,700Arsenic about 21 in 100Nitrate 0.6 mg/L
- Pipestone CountyWell users 1,600Arsenic about 5 in 100Nitrate 0.5 mg/L
- Big Stone CountyWell users 1,600Arsenic about 24 in 100Nitrate 0.3 mg/L
- Lincoln CountyWell users 1,400Arsenic about 5 in 100Nitrate 0.2 mg/L
- Traverse CountyWell users 1,300Arsenic about 9 in 100Nitrate 0.0 mg/L
- Kittson CountyWell users 900Arsenic about 6 in 100Nitrate 0.1 mg/L
Each mark = 1 in 100 well users the model places above 10 µg/L arsenic (scale 0–10)10 mg/L nitrate: the federal limit (MCL) for public systems
- These figures describe the area, not your well. Only a lab test shows what’s in your water.
- CDC says the Well Water Index figures “do not describe risk to individual wells.” (CDC Tracking Network)
- The arsenic model is better at spotting low-arsenic areas than at confirming high ones.
- Well-user counts are 2010 USGS estimates; tract values are averages over each census tract.
- Total coliform bacteriaEvery year
- NitrateEvery year
- Total dissolved solidsEvery year
- pHEvery year
- ArsenicAsk your local health department
EPA: Private Drinking Water Wells · CDC: Guidelines for Testing Well Water
Use a state-certified lab
Minnesota Department of Health lists the laboratories certified to test drinking water in Minnesota.
Screening tells you if something is worth a closer look
A lab result is the number you can act on.
As an Amazon Associate, PurityMap earns from qualifying purchases. Affiliate disclosure
Lab-certified results
ETR Labs Basic Water Quality Test Kit
ETR Laboratories
50+ substances, including lead, copper, arsenic, nitrate, hardness and coliform bacteria
- Analyzed by Environmental Testing and Research Laboratories (ETR Labs), Leominster, MA · ISO/IEC 17025:2017, ANAB certificate AT-2638
- Turnaround: 2–4 business days after the lab receives it
What it can't tell you: It does not test PFAS, and not every result on the panel falls under the lab's accredited scope.
Screening: quick check, not lab-grade
Watersafe Drinking Water Test Kit
Silver Lake Research
Lead, bacteria, nitrate, copper, iron, chlorine, hardness and pH
- Turnaround: Minutes; the bacteria test can take up to 48 hours
What it can't tell you: Each test gives a yes/no or a rough range, not a lab number, and it cannot detect PFAS or arsenic.
A mail-in kit’s lab is accredited (ISO/IEC 17025) but may not be certified by your state. For a home sale, a loan, or a health-department follow-up, use a state-certified lab.
Minnesota well water
Sources: CDC Well Water Index (2024) · USGS arsenic and nitrate models · USGS domestic well populations · EPA and CDC testing guidance. Data last updated 2026-10-08. All sources →
How many people use private wells in Minnesota?
About 1.1 million people across 87 Minnesota counties, by the USGS 2010 estimate. USGS models place about 101,400 of them in areas where wells are likely to be above the 10 µg/L arsenic limit. These are area estimates, not well results.
Are private wells regulated in Minnesota?
The quality and safety of drinking water from private domestic wells are not regulated by the Federal Government under the Safe Drinking Water Act nor by most state governments and laws. (EPA) Testing and treatment are the owner's responsibility.
Where can I get my well tested in Minnesota?
Minnesota Department of Health keeps the list of laboratories certified to test drinking water in Minnesota. Only use laboratories that are certified to do drinking water testing. (EPA)