Flood Hazard Overlay Zone

Flood Hazard Overlay Zone

In order for Clatsop County residents to be eligible for the National Flood Insurance Program (NFIP) the County has agreed to adopt and enforce a floodplain management ordinance that meets or exceeds the NFIP requirements set by the Federal Emergency Management Agency (FEMA). Clatsop County began participating in the NFIP in 1978.

Ordinance 10-03, adopted on Sept. 8, 2010 by the Clatsop County Board of Commissioners, amends the Clatsop County Land and Water Development and Use Ordinance #80-14 - Section 4.000 Flood Hazard Overlay and adopts new FEMA National Flood Insurance Rate Maps. View LWDUO Section 4.000.

If you feel the new FEMA flood maps do not accurately reflect the flood risk to your property, you may pursue a Letter of Map Amendment from FEMA.

Flood Hazard Zones

 

The land area covered by the floodwaters of the base flood is the Special Flood Hazard Area (SFHA) in NFIP maps. The SFHA is the area where the NFIP's floodplain management regulations must be enforced and the area where the mandatory purchase of flood insurance applies. All developments in a Special Flood Hazard Area requires a permit from the Land Use Planning office.

What is an SFHA (aka “flood zone”)?
The land area covered by the floodwaters of the base flood is the Special Flood Hazard Area (SFHA) in NFIP maps. The SFHA is the area where the NFIP's floodplain management regulations must be enforced and the area where the mandatory purchase of flood insurance applies. All developments in a Special Flood Hazard Area requires a permit from the Land Use Planning office.

Zone A - Areas subject to inundation by the 1-percent-annual chance flood event generally determined using approximate methodologies. Because detailed hydraulic analyses have not been permformed, no Base Flood Elevations (BFEs) or flood depths are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply

Zone AE - Areas subject to inundation by the 1-percent-annual-chance flood event determined by detailed methods. Base Flood Elevations (BFEs) are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply.

Zone AH - Areas subject to inundation by 1-percent-annual-chance shallow flooding (usually areas of ponding) where average depths area between one and three feet. Base Flood Elevations (BFEs) derived from detailed hydraulic analyses are shown in this zone. Mandatory flood insurance purchase requirements and floodplain management standards apply.

Zone AR - Areas subject to inundation by 1-percent-annual-chance shallow flooding (usually sheet flow on sloping terrain) where average depths are between one and three feet. Average flood depths derived from detailed hydraulic analyses are shown in this zone. Mandatory flood insurance purchase requirements and floodplain management standards apply.

Zone V - Areas subject to inundation by 1-percent-annual-chance shallow flooding (usually sheet flow on sloping terrain) where average depths area between one and three feet. Average flood depths derived from detailed hydraulic analyes are shown in this zone. Mandatory flood insurance purchase requirements and floodplain management standards apply.

Zone VE - Areas subject to inundation by 1-percent-annual-chance flood event with addional hazards due to storm-induced velocity wave action. Base Flood Elevations (BFEs) derived from detailed hydraulic analyes are shown. Mandatory flood insurance purchase requirements and floodplain management standards apply.

Get More Information

For additional information on flood design specifications, please contact the Building Codes or Land Use Planning offices.