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privatewelldata / Counties

Well water by county: Michigan

Across 49 counties in Michigan, 166 of 1077 sampled wells (15%) were above the arsenic limit and 32 of 1970 (2%) above the nitrate limit. Updated 2026-10-18. Source: Water Quality Portal (USGS, EPA, NWQMC), siteType=Well.

Share of sampled wells whose latest result is above the EPA limit (arsenic 10 µg/L, nitrate 10 mg/L as N).

Share of sampled wells above the limit, by county (% of wells). Source: USGS/EPA Water Quality Portal · privatewelldata.com
CountyArsenic > 10 µg/LNitrate > 10 mg/L
Alger County0% of 230% of 25
Antrim County–0% of 15
Arenac County7% of 15–
Baraga County0% of 160% of 18
Barry County–0% of 21
Bay County3% of 300% of 22
Calhoun County0% of 170% of 10
Chippewa County0% of 200% of 14
Clinton County13% of 160% of 54
Delta County0% of 150% of 35
Dickinson County–10% of 41
Eaton County0% of 210% of 38
Genesee County42% of 240% of 26
Gladwin County6% of 170% of 15
Gogebic County0% of 109% of 11
Grand Traverse County3% of 361% of 217
Gratiot County19% of 210% of 19
Hillsdale County8% of 126% of 17
Huron County50% of 700% of 46
Ingham County4% of 780% of 115
Ionia County0% of 156% of 18
Iosco County15% of 132% of 62
Iron County–0% of 11
Isabella County0% of 180% of 12
Jackson County7% of 270% of 19
Kalamazoo County2% of 5311% of 64
Kent County0% of 130% of 17
Lapeer County76% of 330% of 19
Leelanau County–0% of 17
Lenawee County–0% of 17
Livingston County7% of 428% of 53
Marquette County3% of 341% of 124
Menominee County0% of 140% of 14
Midland County0% of 250% of 21
Monroe County0% of 490% of 69
Montcalm County0% of 11–
Muskegon County0% of 170% of 11
Oakland County25% of 751% of 298
Ottawa County–0% of 10
Roscommon County–0% of 18
Saginaw County7% of 430% of 39
Sanilac County55% of 20–
Schoolcraft County–0% of 12
Shiawassee County62% of 130% of 12
St. Clair County31% of 160% of 41
Tuscola County24% of 210% of 13
Van Buren County19% of 4312% of 42
Washtenaw County34% of 291% of 178
Wayne County33% of 12–