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Benton County, OR Environmental Rules: Flood Zones (2026)

Significant Restrictions

Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

FEMA flood zone rules in Benton County, OR, also called floodplain regulations or special flood hazard area (SFHA) rules, determine flood insurance requirements and elevation standards for new construction.

Key Facts

Permit required: before any SFHA construction, fill, or grading
Non-residential structures: prohibited in the floodplain
Fine, single violation: $500
Fine, continuing violation: $1,000
Reviewed by: Floodplain Administrator and County Engineer
Governing maps: 2016 Flood Insurance Study, FIRM panels

FEMA Flood Zone Lookup

FEMA assigns every parcel in the U.S. a flood-hazard designation on its Flood Insurance Rate Maps (FIRMs). Zones starting with A or V are high-risk Special Flood Hazard Areas where federally backed mortgages require NFIP flood insurance. Zone X indicates moderate-to-minimal risk, where insurance is optional but often recommended. Your specific zone determines insurance cost, build elevation, and permit requirements in Benton County, OR.

Zone	What it means	NFIP required?
A	High-risk flood area; 1% annual chance flood, no detailed analysis.	Yes
AE	High-risk; same as A but with established Base Flood Elevations.	Yes
AH	High-risk shallow flooding (1-3 ft), usually ponding.	Yes
AO	High-risk shallow flooding (1-3 ft) with sheet flow on sloping terrain.	Yes
V	High-risk coastal zone subject to wave action (no BFE).	Yes
VE	High-risk coastal zone with wave action and established BFEs.	Yes
X (shaded)	Moderate risk; between the 1% and 0.2% annual chance flood.	Recommended
X	Minimal risk; outside the 0.2% annual chance floodplain.	No

Look up Benton County, OR on the FEMA flood map

FEMA maps update periodically; verify zone before buying flood insurance or building.

Summary

Any construction, substantial improvement, manufactured dwelling placement, or grading within a Benton County special flood hazard area requires a floodplain development permit under BCC 83.250 before work begins. New or expanded commercial, industrial, and other non-residential structures are flatly prohibited within the floodplain unless no buildable land exists outside it, and code violations carry fines of $500 per occurrence, $1,000 if continuing.

These county ordinances apply to unincorporated areas of Benton County. Incorporated cities within the county may have their own rules that take precedence over county-level regulations.

(3)In addition to any other remedy provided by law to the County, the County may seek a fine of $500 for each separate violation and a fine of $1,000 for a continuing violation of any County ordinance, pursuant to this ordinance. ... (1)A floodplain development permit shall be obtained prior to construction of a new structure, substantial improvement to any structure, the placement of a manufactured dwelling, or the initiation of other land development activities including, but not limited to, fencing, mining, dredging, filling, grading, paving, excavation or drilling operations within any area horizontally within the special flood hazard area established in section BCC 83.110. ... (1)New or expanded primary commercial, industrial, and other non-residential structures, other than agricultural structures, are prohibited within the floodplain. If there is insufficient buildable land outside the floodplain to allow reasonable development of the property, a new or expanded primary structure may be authorized through the procedure specified in BCC 83.620(3).

View official code

Full Breakdown

Chapter 83, the Floodplain Management Overlay Zone, applies to every special flood hazard area in unincorporated Benton County as mapped on the Flood Insurance Study for Benton County, Oregon and Incorporated Areas, revised December 8, 2016, and its accompanying Flood Insurance Rate Maps. 250(1) requires a floodplain development permit before construction of a new structure, substantial improvement, placement of a manufactured dwelling, or other land development activities including, but not limited to, fencing, mining, dredging, filling, grading, paving, excavation or drilling operations anywhere within the mapped special flood hazard area.

220 for floodway location, compliance with the substantial-improvement threshold, watercourse alteration, fill or excavation, and whether the project would raise flood risk to neighboring properties. 620(3). New dwellings face a parallel default prohibition, also limited to vacant-land exceptions reviewed administratively by the Planning Official. 2-foot floodway rise standard and separate vegetation and fill-volume rules for High- and Partial-Protection Floodplain areas. 420, and never within a mapped floodway if they would raise flood levels.

Violations & Fines

Developing within a special flood hazard area without the required BCC 83.250 permit, or in violation of the BCC 83.610 prohibition on new non-residential structures, is enforced by Benton County under BCC Chapter 31's escalating response procedure. BCC 31.125(3) authorizes the County to seek a fine of $500 for each separate violation and a fine of $1,000 for a continuing violation, in addition to injunction, abatement, or mandamus remedies through Benton County Circuit Court.

Frequently Asked Questions

Do I need a permit to fill or grade land in a Benton County flood zone?

Yes. BCC 83.250(1) requires a floodplain development permit before any construction, substantial improvement, manufactured dwelling placement, fencing, mining, dredging, filling, grading, paving, or drilling activity within a mapped special flood hazard area, reviewed by the Floodplain Administrator and County Engineer.

Can I build a new commercial building in the unincorporated county's floodplain?

No, not as a matter of right. BCC 83.610(1) prohibits new or expanded primary commercial, industrial, and other non-residential structures within the floodplain, allowing an exception only when the applicant proves there is no buildable land outside the floodplain on the property, triggering review under BCC 83.620(3).

What happens if I develop in the floodplain without a permit?

Benton County Code Compliance can file an infraction complaint under BCC Chapter 31, which authorizes a fine of $500 for a single violation and $1,000 for a continuing violation, plus injunction or abatement action through Benton County Circuit Court to stop or undo the unpermitted work.

Are there special floodplain rules for the Corvallis Urban Fringe?

Yes. BCC 83.700 adds a stricter 0.2-foot rise standard for the floodway boundary in the Corvallis Urban Fringe, plus separate vegetation-removal and fill-volume-exchange rules for land mapped as High-Protection or Partial-Protection Floodplain, on top of the countywide Chapter 83 standards.

Sources & Official References

[1]Benton County Code of Ordinances (Municode) - Ch. 83, Floodplain Management Overlay; Ch. 31, Enforcement

Other rules in Benton County

Animal Ordinances: Dog Leash LawsSome Restrictions Stormwater ManagementSignificant Restrictions Erosion ControlSome Restrictions Defensible SpaceSome Restrictions Flood Elevation RequirementsSome Restrictions Noise Ordinances: Barking DogsSome Restrictions Animal Ordinances: Bird ProtectionSignificant Restrictions Animal Ordinances: Veterinary Clinic ZoningSome Restrictions Animal Ordinances: Wildlife Rescue PermitsFew Restrictions Animal Ordinances: Exotic PetsHeavy Restrictions

All Benton County rules

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