Lewis County, WA zoning map, flood zone and property lines by address
Free, no account. Or open the Washington map and tap a lot.
Towns in Lewis County: Centralia, Chehalis, Fords Prairie.
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 111 FIRM panels covering Lewis County, the newest effective May 2024; 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 Washington Technology Solutions (WaTech), statewide parcels from the counties, so a Lewis lot shows the same lines the county assessor draws. Lewis County covers about 1,537,782 acres of land and 21,478 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 Centralia, Chehalis each zone the land inside their limits. ParcelSheet shows the use the county assessor lists for the lot and links the county planning department for the district, the uses it allows and the lot size it needs.
ADU and guest houses
Under Washington's Planning Enabling Act and Growth Management Act (Revised Code of Washington Chapters 36.70 and 36.70A), 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 department 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 WA641, Lewis County Area, Washington, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Lewis County needs a permit from the Lewis County health department (local health jurisdiction, under Washington State Department of Health on site sewage 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 Centralia and Chehalis 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 111 flood map panels covering Lewis County, the newest effective May 2024. 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 Washington 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 Centralia, Chehalis) 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 Washington's Planning Enabling Act and Growth Management Act (Revised Code of Washington Chapters 36.70 and 36.70A), 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 Lewis County health department (local health jurisdiction, under Washington State Department of Health on site sewage rules). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area WA641 (Lewis County Area, Washington).
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 Centralia, Chehalis). 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: Cowlitz County, Grays Harbor County, Pacific County, Pierce County, Skamania County, Thurston County, Wahkiakum County, Yakima County.
The Washington map · All Washington counties · Flood zones explained · FIRM panels and LOMAs · All 50 states