Sanilac County, MI zoning map, flood zone and property lines by address
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Towns in Sanilac County: Sandusky, Croswell, Marlette.
Flood zone by address
ParcelSheet reads FEMA's National Flood Hazard Layer at the lot: the zone, whether it is a high risk area where lenders ask for flood insurance, and the base flood elevation where FEMA lists one. FEMA's countywide study for Sanilac County has 91 FIRM panels, the newest effective August 2021; coastal V zones, where waves add to the flood, are mapped along its shore.
The official panel and any Letter of Map Amendment are at FEMA's Map Service Center. An elevation certificate for a Sanilac house comes from a licensed surveyor and is often on file with the county or city building office.
Property lines
The parcel outline, parcel number and mapped size come from the Michigan county parcel layers (each county publishes its own), so a Sanilac lot shows the same lines the township or city assessor draws. Sanilac County covers about 616,046 acres of land and 401,516 acres of water.
Mapped lines are approximate. The Sanilac County township or city assessor keeps the parcel record (Sanilac 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 Sanilac County, Sandusky, Croswell, Marlette each zone the land inside their 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 Sanilac 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 a Sanilac 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. Sanilac County is soil survey area MI151, Sanilac County, Michigan, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Sanilac County needs a permit from the Sanilac County health department (local health department, under Michigan EGLE onsite wastewater rules).
Setbacks
Setbacks in Sanilac 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 Sandusky, Croswell, Marlette for land inside their limits.
Hazards that apply
- Storm surge. Sanilac County has coastal V zones on its FEMA map, so storm surge reaches its shore. The county's evacuation zones are on its emergency management site; ParcelSheet shows the FEMA zone and the 3 ft sea level rise map at the lot.
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Sanilac lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Sanilac County?
Type the address in the box above and ParcelSheet reads FEMA's flood zone at the lot's center. FEMA's countywide flood map for Sanilac County has 91 panels, the newest effective August 2021. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Sanilac County?
Open the Michigan map, type the address, and the parcel outline from the Sanilac 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 Sanilac County?
Zoning in Sanilac County is set by the county, the township, or the city or village, depending on where the lot is (such as Sandusky, Croswell). 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 Sanilac 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 Sanilac 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 Sanilac County?
Yes. A new or changed septic system in Sanilac County needs a permit from the Sanilac 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 MI151 (Sanilac County, Michigan).
What can I build on 5 acres in Sanilac County?
Zoning in Sanilac County is set by the county, the township, or the city or village, depending on where the lot is (such as Sandusky, Croswell). 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 Sanilac County website.
What are the residential setbacks in Sanilac County (2026)?
Setbacks in Sanilac 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 Sanilac County website.
Next to Sanilac County: Huron County, Lapeer County, St. Clair County, Tuscola County.
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