Radon and home risks by county
Radon in Michigan
9 of Michigan's 83 counties are in EPA's highest radon zone, home to about 12% of the state's residents. Radon zones describe an area's potential; EPA recommends testing every home regardless of zone.
Zone 1 counties
9
high radon potential
Zone 2 counties
32
moderate potential
Zone 3 counties
42
low potential
Counties with water violations
50
since 2016; 12 with unresolved ones
Find your county by ZIP
Zone 1: high potential (9 counties)
| County | Residents | Water systems | Health violations since 2016 | Unresolved |
|---|---|---|---|---|
| Branch County | 46,187 | 13 | 0 | 0 |
| Calhoun County | 133,785 | 19 | 3 | 0 |
| Cass County | 51,550 | 19 | 2 | 0 |
| Hillsdale County | 45,590 | 12 | 1 | 0 |
| Jackson County | 160,233 | 24 | 2 | 0 |
| Kalamazoo County | 264,780 | 23 | 5 | 0 |
| Lenawee County | 97,746 | 28 | 28 | 0 |
| St. Joseph County | 61,171 | 17 | 1 | 1 |
| Washtenaw County | 373,875 | 32 | 4 | 0 |
Zone 2: moderate potential (32 counties)
| County | Residents | Water systems | Health violations since 2016 | Unresolved |
|---|---|---|---|---|
| Alcona County | 10,624 | 6 | 0 | 0 |
| Alger County | 8,695 | 5 | 2 | 0 |
| Alpena County | 28,903 | 3 | 0 | 0 |
| Antrim County | 24,536 | 13 | 2 | 0 |
| Baraga County | 8,169 | 3 | 1 | 0 |
| Barry County | 64,025 | 17 | 15 | 0 |
| Charlevoix County | 26,105 | 18 | 0 | 0 |
| Clinton County | 80,050 | 11 | 1 | 1 |
| Dickinson County | 25,995 | 7 | 0 | 0 |
| Eaton County | 109,494 | 17 | 2 | 0 |
| Emmet County | 33,949 | 39 | 1 | 0 |
| Genesee County | 402,279 | 45 | 25 | 1 |
| Gogebic County | 14,217 | 8 | 0 | 0 |
| Houghton County | 38,041 | 17 | 1 | 0 |
| Ingham County | 290,427 | 23 | 0 | 0 |
| Ionia County | 66,250 | 18 | 5 | 0 |
| Iron County | 11,709 | 15 | 0 | 0 |
| Kent County | 673,002 | 44 | 4 | 0 |
| Keweenaw County | 2,161 | 5 | 1 | 0 |
| Lapeer County | 89,168 | 14 | 4 | 0 |
| Leelanau County | 22,871 | 15 | 0 | 0 |
| Livingston County | 196,976 | 47 | 22 | 2 |
| Marquette County | 67,979 | 24 | 5 | 1 |
| Menominee County | 23,050 | 5 | 4 | 0 |
| Monroe County | 156,045 | 10 | 0 | 0 |
| Montcalm County | 69,314 | 13 | 0 | 0 |
| Montmorency County | 9,828 | 3 | 0 | 0 |
| Oakland County | 1,296,888 | 108 | 16 | 3 |
| Otsego County | 26,083 | 11 | 0 | 0 |
| Presque Isle County | 13,230 | 5 | 0 | 0 |
| Sanilac County | 40,293 | 20 | 2 | 1 |
| Shiawassee County | 67,982 | 21 | 13 | 0 |
Zone 3: low potential (42 counties)
| County | Residents | Water systems | Health violations since 2016 | Unresolved |
|---|---|---|---|---|
| Allegan County | 122,429 | 50 | 3 | 1 |
| Arenac County | 15,087 | 9 | 1 | 0 |
| Bay County | 102,651 | 21 | 0 | 0 |
| Benzie County | 18,520 | 10 | 3 | 0 |
| Berrien County | 152,703 | 41 | 22 | 0 |
| Cheboygan County | 25,964 | 10 | 0 | 0 |
| Chippewa County | 36,253 | 6 | 0 | 0 |
| Clare County | 31,405 | 4 | 0 | 0 |
| Crawford County | 13,599 | 3 | 0 | 0 |
| Delta County | 36,687 | 8 | 13 | 0 |
| Gladwin County | 25,995 | 8 | 3 | 1 |
| Grand Traverse County | 96,625 | 24 | 1 | 0 |
| Gratiot County | 41,372 | 11 | 1 | 0 |
| Huron County | 30,780 | 20 | 2 | 0 |
| Iosco County | 25,361 | 11 | 4 | 0 |
| Isabella County | 65,072 | 13 | 1 | 0 |
| Kalkaska County | 18,618 | 2 | 0 | 0 |
| Lake County | 13,005 | 4 | 1 | 1 |
| Luce County | 6,328 | 3 | 0 | 0 |
| Mackinac County | 11,144 | 4 | 3 | 0 |
| Macomb County | 886,175 | 27 | 1 | 0 |
| Manistee County | 25,519 | 10 | 0 | 0 |
| Mason County | 29,093 | 9 | 0 | 0 |
| Mecosta County | 41,947 | 13 | 2 | 0 |
| Midland County | 84,022 | 9 | 0 | 0 |
| Missaukee County | 15,239 | 3 | 0 | 0 |
| Muskegon County | 177,428 | 24 | 0 | 0 |
| Newaygo County | 51,504 | 9 | 2 | 0 |
| Oceana County | 27,014 | 5 | 0 | 0 |
| Ogemaw County | 20,985 | 7 | 0 | 0 |
| Ontonagon County | 5,824 | 5 | 0 | 0 |
| Osceola County | 23,484 | 5 | 0 | 0 |
| Oscoda County | 8,596 | 4 | 0 | 0 |
| Ottawa County | 306,235 | 26 | 5 | 0 |
| Roscommon County | 23,932 | 17 | 3 | 0 |
| Saginaw County | 187,714 | 26 | 3 | 0 |
| Schoolcraft County | 8,178 | 4 | 0 | 0 |
| St. Clair County | 160,308 | 21 | 1 | 0 |
| Tuscola County | 52,757 | 15 | 0 | 0 |
| Van Buren County | 76,129 | 27 | 6 | 0 |
| Wayne County | 1,771,063 | 44 | 3 | 1 |
| Wexford County | 34,460 | 8 | 3 | 1 |
How to read this table
Water systems counts community systems that list the county in their service area; one system can serve several counties. Health violations are breaches of a legal limit or treatment rule recorded by EPA since January 2016, not paperwork lapses. A violation stays unresolved until the state records it as fixed.
Other states
- Arizona
- California
- Colorado
- Florida
- Idaho
- Illinois
- Iowa
- Minnesota
- New Jersey
- New York
- Ohio
- Pennsylvania
- Texas
- Utah
Sources: EPA Map of Radon Zones, EPA ECHO Safe Drinking Water Act data (2026Q3, published October 2026), US Census Bureau Vintage 2024 estimates. See the methodology.