FEMA Floodplain Maps Effective September 17, 2010
New coastal preliminary maps released May 2016
***See bottom of page for Interactive Map of flood hazards***
Principal Flood Problems
Flooding in Clatsop County occurs principally during the winter months. The most extensive flooding occurs in the low-lying coastal and estuary areas. In these areas, flooding is a result of high spring tides and strong winds from winter storms. Heavy rains with some snowmelt produce the highest runoff flows during the winter months. The storms that produce the storm surges also bring heavy rains; therefore, the high river flows are held back by tides, producing the greatest flooding at river mouths. default Read more...
Countywide update since previous mapping
Flood plain boundaries for most of the flooding sources in the County were digitized from the effective FIRM and the Floodway panels. Aerial photography and USGS topographic maps were used to adjust floodplain and floodway boundaries where appropriate. As a countywide update for Clatsop County, floodplain boundaries of Rock creek and Nehalem River were revised using new detailed studies and topographic mapping with a contour interval of two feet.
The levees along the Columbia river do not meet FEMA 65.10 stipulated minimum requirements. In the countywide mapping update, flood plain of the Columbia River is expanded as if no levees were existed. However no new hydraulic studies were conducted to determine the water elevation for without levee scenario for Columbia river. With the consultation FEMA RPO, more conservative, effective riverward BFEs were extended on to both sides of the river across the flood plain. The BFEs and still water elevations are based on the assumption that levees providing protection for 1% flood discharge.
Current products to download
- A "KML" is a file that can be downloaded and opened directly in Google Earth, ArcGIS Explorer and other viewing software available on the Internet. The KML below is for the Special Flood Hazard Area (SFHA), also known as the "100-year" flood.
- A Flood Insurance Study (FIS) is the publication developed in conjunction with the Flood Insurance Rate Map (FIRM) and discusses the engineering methods used to develop the FIRMs. The study also contains flood profiles for studied flooding sources and can be used to determine Base Flood Elevations for some areas.
Download FIS (2008):
FEMA has contracted with DOGAMI for new county-wide floodplain mapping. The project has been delayed some due to levee issues and Zone A remodeling. Preliminary FIRMs along the "open coast" available from the FEMA Map Service Center: https://msc.fema.gov/portal/advanceSearch Columbia River Estuary release has been delay due to continued analysis.
Snapshots around the county
Note - For general information only - DO NOT use for regulatory purposes, especially for non-modernized areas: see "description" for source information and disclaimer
(hint: once in Viewer select "Basemap" in upper left corner for imagery background)