Ontonagon County, MI zoning map, flood zone and property lines by address
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Towns in Ontonagon County: Ontonagon.
Property lines
The parcel outline, parcel number and mapped size come from the Michigan county parcel layers (each county publishes its own), so an Ontonagon lot shows the same lines the township or city assessor draws. Ontonagon County covers about 839,026 acres of land and 1,554,856 acres of water.
Mapped lines are approximate. The Ontonagon County township or city assessor keeps the parcel record (Ontonagon County website); a licensed surveyor sets the true corners.
Zoning
In Michigan zoning is set by the county, the township, or the city or village, depending on where the lot is: in Ontonagon County, Ontonagon zones the land inside its limits. ParcelSheet shows the use code on the lot's parcel record and the municipality it sits in; the township or city zoning office has the district, the uses it allows and the lot size it needs. The Ontonagon County website lists the county's municipalities.
ADU and guest houses
Under Michigan Zoning Enabling Act (Public Act 110 of 2006, MCL 125.3101 and following), the county, the township, or the city or village, depending on where the lot is can allow an accessory dwelling unit on a lot with a house. Whether an Ontonagon lot can add one depends on its district; the township or city zoning office has the rule. ParcelSheet shows the mapped lot size and the ground's slope, the first two things the question turns on.
Septic and soil
ParcelSheet reads the USDA soil survey at the lot: the soil's name, its septic absorption rating and whether it is prime farmland. Ontonagon County is soil survey area MI131, Ontonagon County, Michigan, last updated August 2026, on Web Soil Survey.
A new or changed septic system in Ontonagon County needs a permit from the Ontonagon County health department (local health department, under Michigan EGLE onsite wastewater rules).
Setbacks
Setbacks in Ontonagon County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the township or city zoning office gives them for the lot's district, and Ontonagon for land inside its limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near an Ontonagon lot and the Forest Service wildfire hazard rating at it.
Questions
How do I find property lines in Ontonagon County?
Open the Michigan map, type the address, and the parcel outline from the Ontonagon County township or city assessor shows on the map with its parcel number and mapped size. Mapped lines are approximate; only a licensed surveyor sets the true corners.
What is my property zoned in Ontonagon County?
Zoning in Ontonagon County is set by the county, the township, or the city or village, depending on where the lot is (such as Ontonagon). ParcelSheet shows the use code on the parcel record and names the municipality; the township or city zoning office has the final word.
Can I build an ADU in Ontonagon County?
Under Michigan Zoning Enabling Act (Public Act 110 of 2006, MCL 125.3101 and following), the county, the township, or the city or village, depending on where the lot is can allow an accessory dwelling unit, and each sets its own rules. In Ontonagon County ask the township or city zoning office for the lot's district first; ParcelSheet shows the lot size as mapped so you can see the room you have.
Do I need a septic permit in Ontonagon County?
Yes. A new or changed septic system in Ontonagon County needs a permit from the Ontonagon County health department (local health department, under Michigan EGLE onsite wastewater rules). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area MI131 (Ontonagon County, Michigan).
What can I build on 5 acres in Ontonagon County?
Zoning in Ontonagon County is set by the county, the township, or the city or village, depending on where the lot is (such as Ontonagon). The zoning district decides the uses, how many homes and the smallest lot it allows on 5 acres. ParcelSheet shows the lot size as mapped and the use code on the parcel record; the township or city zoning office has the district and its rules. See the Ontonagon County website.
What are the residential setbacks in Ontonagon County (2026)?
Setbacks in Ontonagon County come from the zoning code of the municipality the lot sits in: the front, side and rear distances depend on the lot's district. ParcelSheet does not draw setback lines or give a number it did not read; the township or city zoning office gives them for the district. See the Ontonagon County website.
Next to Ontonagon County: Gogebic County, Houghton County, Iron County, Keweenaw County.
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