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Floodplain Management

Floodplain Management

The City of Astoria takes part in the National Floodplain Insurance Program (NFIP), which requires the acceptance of floodplain maps and accompanying construction requirements.

The Flood Hazard Overlay (FHO) in Article 14 of the Astoria Development Code provides standards for construction. Most notably, the lowest finished floor must be 1 ft. above the base flood elevation (BFE) established by the FEMA floodplain maps. An elevation certificate may be required for construction within or near a floodplain in order to document the finished floor elevation in relation to the floodplain elevation.

The Flood Hazard Overlay (FHO) map can be found under the flood hazard option on the City’s GIS map - GIS Map. Use the “FEMA flood zone” option. Any property within the “AE” zone is within the 100 year floodplain and requires adherence to FHO requirements.

LOMR/CLOMR & Endangered Species Act Announcement

FEMA is temporarily suspending applications for Letters of Map Revision (LOMR) or Conditional Letters of Map Revision (CLOMR) beginning August 1, 2024. FEMA is in the process of incorporating the Endangered Species Act (ESA) into their rules. Cities that take part in the National Floodplain Insurance Program (NFIP) will be required to update their rules accordingly. These changes are expected to be adopted in 2027.

Adoption of New Maps

Beginning in early 2025, FEMA will begin a public process to adopt new floodplain maps. The new maps take into account a new flood study and include improvements in identifying and managing hydrologic and hydraulic conditions that cause flooding. The draft maps can be found here - Draft FEMA Map.

In the City, there are two changes that may affect properties. First, the extent of the floodplain will expand affecting properties in the Alderbrook neighborhood. Overall, within the City, 28 properties are being added to the floodplain while 25 will be removed for a net addition of 3 additional properties.

Second, the “AE” floodplain zone is being changed to a “VE” zone. The new “VE” zone takes into account velocity of river water and coastal storm surges. The previous flood study, which the floodplain maps are based on, only took the elevation of flood water into consideration.  

The “VE” zone will account for the velocity of wave action on structures in the floodplain. Once the maps are adopted, it’s expected that proposed structures within the floodplain will be required to add bracing to structural support members to meet code requirements.