Columbia County, OR zoning map, flood zone and property lines by address
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Towns in Columbia County: Saint Helens, Scappoose, Vernonia.
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 Columbia County has 57 FIRM panels, the newest effective November 2010; 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 Columbia 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 Oregon county parcel layers (each county publishes its own), so a Columbia lot shows the same lines the county assessor draws. Columbia County covers about 421,559 acres of land and 19,392 acres of water.
Mapped lines are approximate. The Columbia County assessor keeps the parcel record (Columbia County website); a licensed surveyor sets the true corners.
Zoning
Columbia County zones its unincorporated land, and Scappoose, Vernonia 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 Oregon's county land use planning law (Oregon Revised Statutes Chapter 215), local governments can allow an accessory dwelling unit on a lot with a house. Whether a Columbia 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. Columbia County is soil survey area OR009, Columbia County, Oregon, last updated September 2026, on Web Soil Survey.
A new or changed septic system in Columbia County needs a permit from the Columbia County onsite septic program office (run by the county or by Oregon DEQ, under DEQ onsite rules).
Setbacks
Setbacks in Columbia 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 Scappoose and Vernonia for land inside their limits.
Hazards that apply
- Wetlands and wildfire. ParcelSheet shows the National Wetlands Inventory near a Columbia lot and the Forest Service wildfire hazard rating at it.
Questions
Is my house in a flood zone in Columbia 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 Columbia County has 57 panels, the newest effective November 2010. A lender or insurer uses the official FIRM panel; FEMA's Map Service Center has it.
How do I find property lines in Columbia County?
Open the Oregon map, type the address, and the parcel outline from the Columbia 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 Columbia County?
Zoning in Columbia County is set by the county for unincorporated land and by each city (such as Scappoose, Vernonia) 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 Columbia County?
Under Oregon's county land use planning law (Oregon Revised Statutes Chapter 215), counties and cities can allow an accessory dwelling unit, and each sets its own rules. In Columbia 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 Columbia County?
Yes. A new or changed septic system in Columbia County needs a permit from the Columbia County onsite septic program office (run by the county or by Oregon DEQ, under DEQ onsite rules). ParcelSheet shows the USDA soil survey's septic rating at the lot, from survey area OR009 (Columbia County, Oregon).
What can I build on 5 acres in Columbia County?
Zoning in Columbia County is set by the county for unincorporated land and each city inside its own limits (such as Scappoose, Vernonia). 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 Columbia County website.
What are the residential setbacks in Columbia County (2026)?
Setbacks in Columbia 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 Columbia County website.
Next to Columbia County: Clatsop County, Multnomah County, Washington County.
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