Williams County, ND zoning map, flood zone and property lines by address
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Towns in Williams County: Williston, Tioga.
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 has 31 FIRM panels covering Williams County, the newest effective September 2015; no coastal V zones are mapped in it.
The official panel and any Letter of Map Amendment are at FEMA's Map Service Center. An elevation certificate for a Williams 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 North Dakota GIS Hub parcel layer (from each county), so a Williams lot shows the same lines the county director of tax equalization draws. Williams County covers about 1,329,664 acres of land and 44,933 acres of water.
Mapped lines are approximate. The Williams County director of tax equalization keeps the parcel record (Williams County website); a licensed surveyor sets the true corners.
Zoning
In North Dakota zoning is set by the county, the township or the city, depending on where the lot is: in Williams County, Williston, Tioga 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 county, township or city zoning office has the district, the uses it allows and the lot size it needs. The Williams County website lists the county's municipalities.
ADU and guest houses
Under North Dakota's zoning laws (N.D. Cent. Code chapters 11-33 for counties and 40-47 for cities), the county, the township or the city, depending on where the lot is can allow an accessory dwelling unit on a lot with a house. Whether a Williams lot can add one depends on its district; the county, 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. Williams County is soil survey area ND105, Williams County, North Dakota, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Williams County needs a permit from the Williams County local public health unit (installers are licensed by the ND Department of Environmental Quality).
Setbacks
Setbacks in Williams County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the county, township or city zoning office gives them for the lot's district, and Williston and Tioga for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Williams lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Williams County?
Type the address in the box above and ParcelSheet reads FEMA's flood zone at the lot's center. FEMA has 31 flood map panels covering Williams County, the newest effective September 2015. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Williams County?
Open the North Dakota map, type the address, and the parcel outline from the Williams County director of tax equalization 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 Williams County?
Zoning in Williams County is set by the county, the township or the city, depending on where the lot is (such as Williston, Tioga). ParcelSheet shows the use code on the parcel record and names the municipality; the county, township or city zoning office has the final word.
Can I build an ADU in Williams County?
Under North Dakota's zoning laws (N.D. Cent. Code chapters 11-33 for counties and 40-47 for cities), the county, the township or the city, depending on where the lot is can allow an accessory dwelling unit, and each sets its own rules. In Williams County ask the county, 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 Williams County?
Yes. A new or changed septic system in Williams County needs a permit from the Williams County local public health unit (installers are licensed by the ND Department of Environmental Quality). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area ND105 (Williams County, North Dakota).
What can I build on 5 acres in Williams County?
Zoning in Williams County is set by the county, the township or the city, depending on where the lot is (such as Williston, Tioga). 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 county, township or city zoning office has the district and its rules. See the Williams County website.
What are the residential setbacks in Williams County (2026)?
Setbacks in Williams 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 county, township or city zoning office gives them for the district. See the Williams County website.
Next to Williams County: Burke County, Divide County, McKenzie County, Mountrail County.
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