On Oct. 11, 2023, City Council voted unanimously to adopt zoning code amendments that reduce the impacts of future flooding on those who live or work in or near Portland’s floodplains. The code amendments also protect floodplain habitat for endangered and threatened fish species.
The updates respond to Federal Emergency Management Association (FEMA) guidance on the management of new development along the edges of Portland’s rivers and streams. This is so that homes and businesses located in flood-prone areas continue to qualify for federal flood insurance and disaster relief funds.
The Floodplain Resilience Plan amends the zoning code and associated maps in the following ways:
- Expands environmental zones to apply habitat protections to floodplains that are not already subject to these requirements.
- Updates requirements in areas with a high risk of flooding to better manage tree and vegetation removal and require plantings that will preserve floodplain habitat.
- Requires that development within 170 feet of the Willamette River in the Central City improve floodplain habitat. If the floodplain extends less than 170 feet, the requirement only applies to development proposed in the floodplain.
- Updates floodplain mapping to incorporate new modeling of flood risk along the Willamette River.
City Council added several key amendments to the package, including:
- Extending the expiration date for land use decisions, for projects with multiple buildings and phased developments, from three to seven years.
- Allowing for minor changes to an approved River Review without requiring the project to be subject to current regulations. This only applies if they have changed since the River Review approval. Any new impacts to natural resources resulting from changes must be addressed.
- Continuing to allow replacement of utilities in the floodplain and an Environmental overlay zone if it does not expand the building footprint.
- Allowing existing pump stations near the Willamette River to be replaced or expanded to meet existing and future demand if the expansion does not move the pump station closer to the river.
Effective date of proposed changes
Implementation of the zoning code (Title 33) changes will be phased. Application of the riparian buffer area and its requirements in floodplains within 170 feet of the Willamette River in the Central City - and the associated expansion of the River Environmental overlay zone to encompass it - will take effect on Oct. 1, 2024.
All other zoning code amendments will take effect on March 1, 2024.
Development projects that are submitted before the new rules go into effect will be subject to the current floodplain regulations. Development projects submitted after the effective dates will be subject to the new requirements.
The zoning code amendments can be found in the plan starting on page 68 (Chapter VI., Section C., Zoning Code Amendments).
Bureau of Development Services Chapter 24.50 Flood Hazard Areas Code Update Project
City Council also adopted a package of amendments to floodplain management regulations in the City’s Building Regulations (Title 24) brought by the Bureau of Development Services. Amendments to Title 24 Chapter 24.50, Flood Hazard Areas, will ensure adequate space for the conveyance of flood waters is maintained when development occurs in the floodplain, reducing the risk of flooding on nearby properties.