Lewis County, ID zoning map, flood zone and property lines by address
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Towns in Lewis County: Kamiah, Nezperce.
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 26 FIRM panels covering Lewis County, the newest effective October 2026; 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 Lewis 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 State of Idaho public parcels, from counties that share them, so a Lewis lot shows the same lines the county assessor draws. Lewis County covers about 306,446 acres of land and 578 acres of water.
Mapped lines are approximate. The Lewis County assessor keeps the parcel record (Lewis County website); a licensed surveyor sets the true corners.
Zoning
Lewis County zones its unincorporated land, and Kamiah, Nezperce each zone the land inside their limits. ParcelSheet shows the use the county assessor lists for the lot and links the county planning and zoning office for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under Idaho's Local Land Use Planning Act (Idaho Code Title 67, Chapter 65), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Lewis lot can add one depends on its district; the county planning and 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. Lewis County is soil survey area ID611, Lewis and Nez Perce Counties, Idaho, last updated August 2026, on Web Soil Survey.
A new or changed septic system in Lewis County needs a permit from the public health district that serves Lewis County (under Idaho Department of Environmental Quality rules).
Setbacks
Setbacks in Lewis County come from the zoning district: the front, side and rear distances a house must keep. ParcelSheet does not draw setback lines; the county zoning office gives them for the lot's district, and Kamiah and Nezperce for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Lewis lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Lewis County?
Type the address in the box above and ParcelSheet reads FEMA's flood zone at the lot's center. FEMA has 26 flood map panels covering Lewis County, the newest effective October 2026. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Lewis County?
Open the Idaho map, type the address, and the parcel outline from the Lewis County 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 Lewis County?
Zoning in Lewis County is set by the county for unincorporated land and by each city (such as Kamiah, Nezperce) inside its own limits. ParcelSheet shows the use code the county assessor lists and links the office that sets the zoning; the planning office has the final word.
Can I build an ADU in Lewis County?
Under Idaho's Local Land Use Planning Act (Idaho Code Title 67, Chapter 65), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Lewis County ask the 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 Lewis County?
Yes. A new or changed septic system in Lewis County needs a permit from the public health district that serves Lewis County (under Idaho Department of Environmental Quality rules). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area ID611 (Lewis and Nez Perce Counties, Idaho).
What can I build on 5 acres in Lewis County?
Zoning in Lewis County is set by the county for unincorporated land and each city inside its own limits (such as Kamiah, Nezperce). 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 planning office has the district and its rules. See the Lewis County website.
What are the residential setbacks in Lewis County (2026)?
Setbacks in Lewis County come from the zoning code of the county, or of the city when the lot is inside city limits: 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 zoning office gives them for the district. See the Lewis County website.
Next to Lewis County: Clearwater County, Idaho County, Nez Perce County.
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