Cowlitz County, WA zoning map, flood zone and property lines by address
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Towns in Cowlitz County: Longview, Kelso, Woodland.
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 Cowlitz County has 185 FIRM panels, the newest effective December 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 Cowlitz 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 Cowlitz lot shows the same lines the county assessor draws. Cowlitz County covers about 730,353 acres of land and 16,156 acres of water.
Mapped lines are approximate. The Cowlitz County assessor keeps the parcel record (Cowlitz County website); a licensed surveyor sets the true corners.
Zoning
Cowlitz County zones its unincorporated land, and Longview, Kelso, Woodland 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 Cowlitz 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. Cowlitz County is soil survey area WA015, Cowlitz County, Washington, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Cowlitz County needs a permit from the Cowlitz County health department (local health jurisdiction, under Washington State Department of Health on site sewage rules).
Setbacks
Setbacks in Cowlitz 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 Longview, Kelso, Woodland for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Cowlitz lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Cowlitz 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 Cowlitz County has 185 panels, the newest effective December 2015. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Cowlitz County?
Open the Washington map, type the address, and the parcel outline from the Cowlitz 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 Cowlitz County?
Zoning in Cowlitz County is set by the county for unincorporated land and by each city (such as Longview, Kelso) 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 Cowlitz 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 Cowlitz 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 Cowlitz County?
Yes. A new or changed septic system in Cowlitz County needs a permit from the Cowlitz 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 WA015 (Cowlitz County, Washington).
What can I build on 5 acres in Cowlitz County?
Zoning in Cowlitz County is set by the county for unincorporated land and each city inside its own limits (such as Longview, Kelso). 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 Cowlitz County website.
What are the residential setbacks in Cowlitz County (2026)?
Setbacks in Cowlitz 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 Cowlitz County website.
Next to Cowlitz County: Clark County, Lewis County, Skamania County, Wahkiakum County.
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