TL;DR (generated, confidence: high)

Portland adopted floodplain development regulation updates effective July 31, 2025, implementing FEMA's interim compliance measures to align the National Flood Insurance Program with the Endangered Species Act.

Key points:

Portland City Council adopted changes to floodplain development regulations on July 17, 2025, effective July 31, 2025 (Updates to Floodplain Development Code took effect July 31 ↗)
Changes implement FEMA's Pre-Implementation Compliance Measures (PICMs) to bring the National Flood Insurance Program into compliance with the Endangered Species Act (Updates to Floodplain Development Code took effect July 31 ↗)
New development projects in floodplains must compensate for loss of flood storage volume through soil/rock excavation or removal of permanent structures that displace floodwater (Updates to Floodplain Development Code took effect July 31 ↗)
Stormwater management requirements must align with the City of Portland Stormwater Management Manual (2025 edition) (Updates to Floodplain Development Code took effect July 31 ↗)
Tree replacement required within special flood hazard areas (Updates to Floodplain Development Code took effect July 31 ↗)
Updates align with State of Oregon's Model Flood Hazard Ordinance and follow earlier October 2023 Portland City Council actions (Updates to Floodplain Development Code took effect July 31 ↗)

Entities: organization: Portland City Council · Federal Emergency Management Agency (FEMA) | program: National Flood Insurance Program (NFIP) | legislation: Endangered Species Act (ESA) | code_section: Portland City Code Chapter 24.50 | document: Stormwater Management Manual | ordinance: State of Oregon Model Flood Hazard Ordinance

Updates to Floodplain Development Code took effect July 31

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Source: Updates to Floodplain Development Code took effect July 31 ↗ Last modified: Sun, 19 Apr 2026 20:07:25 GMT

On July 17, the Portland City Council adopted changes to the City’s floodplain development regulations ↗, effective July 31, adopting Pre-Implementation Compliance Measures (PICMs) established by the Federal Emergency Management Agency (FEMA). The PICMs are interim measures required by FEMA to bring the National Flood Insurance Program (NFIP) in Oregon into compliance with the Endangered Species Act (ESA).

Highlights of changes to City’s floodplain development code

The main changes to Portland City Code Chapter 24.50, Flood Hazard Areas ↗, focus on:

Requiring plans for new development projects located in floodplains (flood hazard areas) to compensate for the loss of flood storage volume, through the excavation of soil or rock or the removal of permanent structures that displace floodwater, or both
Ensuring requirements for stormwater management are met as outlined in the City of Portland Stormwater Management Manual ↗
Providing for tree replacement within the special flood hazard area

These changes follow actions taken by the Portland City Council in October 2023 ↗ to better align the City’s floodplain development code with the State of Oregon’s Model Flood Hazard Ordinance and to increase flood storage compensation requirements, coupled with Zoning Code changes enhancing environmental requirements, for certain flood hazard areas.