Michigan well water by county: arsenic and nitrate
Modelled arsenic and nitrate for private-well users in every Michigan county, what to test for, and where to find a certified lab. Private wells aren’t covered by the Safe Drinking Water Act.
All 83 counties
- Oakland CountyWell users 163,600Arsenic about 6 in 100Nitrate 0.1 mg/L
- Genesee CountyWell users 127,500Arsenic about 30 in 100Nitrate 0.0 mg/L
- Kent CountyWell users 88,000Arsenic about 8 in 100Nitrate 1.0 mg/L
- Jackson CountyWell users 75,000Arsenic about 5 in 100Nitrate 0.3 mg/L
- Livingston CountyWell users 73,700Arsenic about 7 in 100Nitrate 0.1 mg/L
- Allegan CountyWell users 65,700Arsenic about 5 in 100Nitrate 0.8 mg/L
- Berrien CountyWell users 59,600Arsenic about 6 in 100Nitrate 0.6 mg/L
- Kalamazoo CountyWell users 55,400Arsenic about 2 in 100Nitrate 1.2 mg/L
- Washtenaw CountyWell users 54,200Arsenic about 12 in 100Nitrate 0.1 mg/L
- Calhoun CountyWell users 54,100Arsenic about 6 in 100Nitrate 1.0 mg/L
- Muskegon CountyWell users 53,200Arsenic about 9 in 100Nitrate 0.6 mg/L
- Lapeer CountyWell users 53,100Arsenic about 57 in 100Nitrate 0.0 mg/L
- Ottawa CountyWell users 51,500Arsenic about 3 in 100Nitrate 0.5 mg/L
- St. Clair CountyWell users 48,400Arsenic about 16 in 100Nitrate 0.0 mg/L
- Van Buren CountyWell users 44,100Arsenic about 2 in 100Nitrate 0.9 mg/L
- Montcalm CountyWell users 41,900Arsenic about 5 in 100Nitrate 1.7 mg/L
- Monroe CountyWell users 41,800Arsenic about 6 in 100Nitrate 0.0 mg/L
- Lenawee CountyWell users 40,900Arsenic about 8 in 100Nitrate 0.1 mg/L
- Barry CountyWell users 39,300Arsenic about 12 in 100Nitrate 0.7 mg/L
- Ingham CountyWell users 39,000Arsenic about 7 in 100Nitrate 0.1 mg/L
- Eaton CountyWell users 39,000Arsenic about 25 in 100Nitrate 0.1 mg/L
- Clinton CountyWell users 38,400Arsenic about 30 in 100Nitrate 0.0 mg/L
- Tuscola CountyWell users 38,200Arsenic about 36 in 100Nitrate 0.0 mg/L
- Saginaw CountyWell users 38,200Arsenic about 46 in 100Nitrate 0.0 mg/L
- Cass CountyWell users 37,800Arsenic about 4 in 100Nitrate 2.1 mg/L
- Newaygo CountyWell users 37,700Arsenic about 2 in 100Nitrate 1.1 mg/L
- Shiawassee CountyWell users 37,700Arsenic about 38 in 100Nitrate 0.0 mg/L
- Grand Traverse CountyWell users 37,200Arsenic about 4 in 100Nitrate 1.0 mg/L
- Ionia CountyWell users 35,000Arsenic about 7 in 100Nitrate 0.7 mg/L
- Macomb CountyWell users 34,400Arsenic about 10 in 100Nitrate 0.1 mg/L
- St. Joseph CountyWell users 31,300Arsenic about 2 in 100Nitrate 1.2 mg/L
- Midland CountyWell users 31,200Arsenic about 20 in 100Nitrate 0.0 mg/L
- Sanilac CountyWell users 29,300Arsenic about 29 in 100Nitrate 0.0 mg/L
- Hillsdale CountyWell users 29,100Arsenic about 7 in 100Nitrate 0.2 mg/L
- Isabella CountyWell users 27,900Arsenic about 23 in 100Nitrate 0.2 mg/L
- Mecosta CountyWell users 27,800Arsenic about 2 in 100Nitrate 1.4 mg/L
- Branch CountyWell users 26,900Arsenic about 4 in 100Nitrate 0.4 mg/L
- Clare CountyWell users 23,000Arsenic about 2 in 100Nitrate 0.4 mg/L
- Gratiot CountyWell users 22,900Arsenic about 50 in 100Nitrate 0.1 mg/L
- Cheboygan CountyWell users 20,000Arsenic about 2 in 100Nitrate 0.1 mg/L
- Gladwin CountyWell users 19,900Arsenic about 6 in 100Nitrate 0.1 mg/L
- Oceana CountyWell users 19,700Arsenic about 4 in 100Nitrate 0.9 mg/L
- Huron CountyWell users 19,600Arsenic about 23 in 100Nitrate 0.0 mg/L
- Marquette CountyWell users 19,200Arsenic about 2 in 100Nitrate 0.1 mg/L
- Emmet CountyWell users 19,100Arsenic about 2 in 100Nitrate 0.3 mg/L
- Wexford CountyWell users 18,900Arsenic about 2 in 100Nitrate 1.0 mg/L
- Roscommon CountyWell users 17,900Arsenic about 2 in 100Nitrate 0.2 mg/L
- Osceola CountyWell users 17,800Arsenic about 2 in 100Nitrate 1.3 mg/L
- Bay CountyWell users 17,600Arsenic about 16 in 100Nitrate 0.0 mg/L
- Otsego CountyWell users 16,900Arsenic about 1 in 100Nitrate 0.5 mg/L
- Ogemaw CountyWell users 16,900Arsenic about 2 in 100Nitrate 0.3 mg/L
- Manistee CountyWell users 16,400Arsenic about 4 in 100Nitrate 0.7 mg/L
- Delta CountyWell users 16,100Arsenic about 3 in 100Nitrate 0.1 mg/L
- Mason CountyWell users 16,000Arsenic about 4 in 100Nitrate 0.9 mg/L
- Antrim CountyWell users 15,600Arsenic about 4 in 100Nitrate 0.5 mg/L
- Leelanau CountyWell users 15,500Arsenic about 5 in 100Nitrate 0.4 mg/L
- Charlevoix CountyWell users 14,900Arsenic about 4 in 100Nitrate 0.5 mg/L
- Kalkaska CountyWell users 14,700Arsenic about 2 in 100Nitrate 0.5 mg/L
- Iosco CountyWell users 14,700Arsenic about 2 in 100Nitrate 0.2 mg/L
- Chippewa CountyWell users 14,600Arsenic about 3 in 100Nitrate 0.1 mg/L
- Alpena CountyWell users 14,200Arsenic about 2 in 100Nitrate 0.2 mg/L
- Menominee CountyWell users 13,000Arsenic about 1 in 100Nitrate 0.1 mg/L
- Benzie CountyWell users 12,800Arsenic about 5 in 100Nitrate 0.5 mg/L
- Missaukee CountyWell users 12,500Arsenic about 2 in 100Nitrate 1.2 mg/L
- Crawford CountyWell users 12,100Arsenic about 2 in 100Nitrate 0.4 mg/L
- Arenac CountyWell users 11,600Arsenic about 15 in 100Nitrate 0.1 mg/L
- Lake CountyWell users 10,700Arsenic about 2 in 100Nitrate 0.8 mg/L
- Alcona CountyWell users 9,600Arsenic about 2 in 100Nitrate 0.4 mg/L
- Presque Isle CountyWell users 9,600Arsenic about 2 in 100Nitrate 0.2 mg/L
- Houghton CountyWell users 9,200Arsenic about 2 in 100Nitrate 0.1 mg/L
- Montmorency CountyWell users 8,900Arsenic about 2 in 100Nitrate 0.3 mg/L
- Oscoda CountyWell users 8,000Arsenic about 2 in 100Nitrate 0.5 mg/L
- Wayne CountyWell users 7,400Arsenic about 3 in 100Nitrate 0.0 mg/L
- Mackinac CountyWell users 7,000Arsenic about 2 in 100Nitrate 0.1 mg/L
- Dickinson CountyWell users 6,500Arsenic about 2 in 100Nitrate 0.1 mg/L
- Alger CountyWell users 6,400Arsenic about 2 in 100Nitrate 0.2 mg/L
- Schoolcraft CountyWell users 4,900Arsenic about 1 in 100Nitrate 0.1 mg/L
- Gogebic CountyWell users 4,100Arsenic about 3 in 100Nitrate 0.0 mg/L
- Ontonagon CountyWell users 3,600Arsenic about 5 in 100Nitrate 0.1 mg/L
- Luce CountyWell users 3,200Arsenic about 2 in 100Nitrate 0.1 mg/L
- Baraga CountyWell users 3,200Arsenic about 2 in 100Nitrate 0.1 mg/L
- Iron CountyWell users 1,600Arsenic about 2 in 100Nitrate 0.1 mg/L
- Keweenaw CountyWell users 530Arsenic about 3 in 100Nitrate 0.0 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
Michigan Department of Environment, Great Lakes, and Energy lists the laboratories certified to test drinking water in Michigan.
Screening tells you if something is worth a closer look
A lab result is the number you can act on.
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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.
Michigan 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 Michigan?
About 2.4 million people across 83 Michigan counties, by the USGS 2010 estimate. USGS models place about 278,600 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 Michigan?
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 Michigan?
Michigan Department of Environment, Great Lakes, and Energy keeps the list of laboratories certified to test drinking water in Michigan. Only use laboratories that are certified to do drinking water testing. (EPA)