Environmental Rules in Hillsboro, OR (2026)
4 verified environmental rules for Hillsboro, Oregon, sourced directly from the municipal code and official government pages.
Verified from official government sources
Stormwater Management
New Hillsboro development with aboveground stormwater facilities must integrate them into site design and meet Clean Water Services' regional runoff treatment standards.
Hillsboro Stormwater Facility Rules
Some RestrictionsHillsboro Community Development Code § 12.50.640.D.2
The Review Authority may condition any Type II or Type III land use application approval to require that the aboveground stormwater facility complies with the applicable provisions of the 2018 CWS Design and Construction Standards Chapter 3 Sensitive Areas and Vegetated Corridors and Chapter 4 Runoff Treatment and Control.
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.
Hillsboro Site Grading Permit Rules
Some RestrictionsHillsboro Community Development Code § 12.50.630.D.1, F
...when grading a site within 25 feet of a property line within or abutting any property zoned single dwelling residential (as listed in Section 12.21.010), on-site grading shall be finished to the surface contours shown in Table 12.50.630-1...If mass grading or stockpiling as defined in Section 12.01.500 is proposed on public or private property, the site grading plan required under D & C Stan...
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.
Hillsboro Floodplain Development Permit Rules
Some RestrictionsHillsboro Community Development Code § 12.27.110.A.1
The Regulatory Floodplain Overlay (RFO) zone applies to special flood hazard area (also known as the "1% annual chance floodplain," "100-year floodplain," "floodplain") identified by the Federal Insurance Administration in a scientific and engineering report titled "Flood Insurance Study for Washington County, Oregon and Incorporated Areas" dated October 19, 2018, with accompanying Flood Insura...
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.
Hillsboro Base Flood Elevation Rules
Some RestrictionsHillsboro Community Development Code § 12.27.135.B.3.a.ii, iii, vi
Residential construction is permitted within the RFO outside of the floodway with the approval of a FA II permit. In addition to the general development standards in Section 12.27.130, the following requirements apply:...ii.All new construction, conversion to residential and substantial improvements of any residential structure shall have the lowest floor, including basement, elevated to at lea...
Looking for Washington County county-wide rules?
County ordinances apply to unincorporated areas and may supplement Hillsboro city rules.
Environmental Rules in Washington County →