Environmental Rules in Hillsboro, OR

If you live in Hillsboro or are thinking about moving there, environmental rules are one of those things you probably won't think about until they affect you directly. Hillsboro has 4 specific rules on the books covering different aspects of environmental rules, and some of them might surprise you.

Stormwater Management

New Hillsboro development with aboveground stormwater facilities must integrate them into site design and meet Clean Water Services' regional runoff treatment standards.

Key details: Applies to: Aboveground stormwater facilities on new development. Technical standard: 2018 CWS Design & Construction Standards. Design requirement: Integrated grading and compatible landscaping. Reviewed at: Type II/III land use approval. Regional authority: Clean Water Services, Washington County.

Land use applications that omit required stormwater facility plans, or facilities that don't meet the incorporated CWS design standards, can be denied or held up with conditions before the project is approved.

Erosion Control

Hillsboro caps how much finished grade can differ from neighboring ground near single-family zones and requires a City-approved grading plan for cut, fill, or stockpiling.

Key details: Triggers a plan: Any excavation, fill, or stockpiling. Near residential zones: 0 to 10 ft max grade differential. Standalone mass grading: Needs Type II Development Review. Plan standard: Public Works D&C Standards § 115.3.

Grading beyond the allowed differential near residential zones, or grading and stockpiling without the required Type II Development Review approval, is a Code violation the City can require to be regraded or halted.

Flood Zones

Hillsboro requires a Floodplain Activity Permit for nearly all development in the FEMA-mapped 1% annual chance floodplain, administered by the City's Floodplain Administrator under the Regulatory Floodplain Overlay zone.

Key details: Permit required: Floodplain Activity (FA) Permit. Governing zone: RFO Regulatory Floodplain Overlay. Flood study date: October 19, 2018. Administered by: City Floodplain Administrator.

Building or filling in the floodplain without an FA Permit is a code violation; the City can require removal, restoration, or retroactive permitting, and unpermitted work can jeopardize residents' flood insurance eligibility.

Flood Elevation Requirements

New homes and additions built inside Hillsboro's Regulatory Floodplain Overlay must have the lowest floor, including any basement, elevated at least one foot above the Base Flood Elevation. The standard is enforced through a Floodplain Activity II permit reviewed by the City's Floodplain Administrator before construction begins.

Key details: Minimum elevation: 1 ft above Base Flood Elevation. Non-residential option: Elevate or floodproof to 1 ft above BFE. Permit required: FA II (Type II procedure). Elevation certificates filed: 3 times during construction. Zone: Regulatory Floodplain Overlay, outside floodway.

Community Development Code § 12.01.150 classifies CDC violations, including building below the required Base Flood Elevation without an approved FA II permit, as infractions subject to the City's civil enforcement provisions. Such violations are also declared nuisances and may be abated under Title 6 of the Hillsboro Municipal Code, giving the City a separate nuisance-abatement track alongside the civil infraction process administered by the Floodplain Administrator and Director.

The Bottom Line

Hillsboro's environmental rules rules are a mixed bag. Some areas are strict, others are relaxed, and the details matter. The best approach is to check the specific rule that applies to your situation rather than assuming Hillsboro is broadly strict or permissive.

Keep in mind that Hillsboro can amend these rules at any council meeting. For the most current version of any rule mentioned here, check the specific ordinance page, where we track updates as they happen.