Washington Department of Ecology, FEMA Revising State Flood Hazard Maps

"The new digital maps are a vast improvement over the old paper maps. They will be more comprehensive, show more on-the-ground information, and be more accessible to citizens and officials who need the information."

by / March 14, 2008

A project currently under way will help Washington landowners and local officials make informed decisions about where it is safe to build in and around areas prone to flooding.

The Federal Emergency Management Agency (FEMA) and the Department of Ecology (Ecology) are updating existing flood hazard maps in several Washington counties that have high risk, flood-prone areas.

In many Washington communities, it has been about 20-30 years since flood hazard maps have been updated. The new maps will depict flood hazards more accurately, including changes in flooding patterns.

The mapping project is part of a nationwide effort by FEMA. Ecology is helping FEMA put the new maps into a digital, electronic format. The more detailed maps will eventually be available on the Internet.

The new digitized maps will better represent all the geographical features and hazards within a particular flood plain. The work will involve a series of engineering assessments, computer modeling, geographic information system (GIS)-based mapping, and public meetings.

According to FEMA Regional Administrator Susan Reinertson, flood plains often cover more than a single county, city, town and related urban growth boundaries.

"We're continuing to improve the quality and accuracy of national flood hazard data by developing Geographic Information System-based products with the best technologies," Reinertson said. "The new digitized maps will provide communities with flood maps and data that are more reliable, easier to use and more readily available."

Completed digital flood hazard maps are available now to jurisdictions in Island, Ferry, Kitsap and Whatcom counties. Preliminary digital maps are available to jurisdictions in Adams, Clark, Grant, King, Pierce and Snohomish counties. New flood hazard maps for jurisdictions in Clallam, Cowlitz, Grays Harbor, Lewis, Skagit, Spokane and Yakima counties are scheduled to be revised within the next two years.

For jurisdictions in Asotin, Benton, Chelan, Columbia, Douglas, Ferry, Franklin, Garfield, Jefferson, Klickitat, Lincoln, Mason, Okanogan, Pacific, Pend Oreille, San Juan, Skamania, Stevens, Thurston, Wahkiakum, Walla Walla and Whitman counties, new flood hazard maps are to be revised in the next three to five years.

"These maps are vital in helping local governments make decisions about where homes, businesses and utilities can be built safely -- where they shouldn't be built due to past and potential flooding," said Ecology's Dan Sokol, who coordinates the National Flood Insurance Program for the state. "The revised maps will help save lives, property and reduce economic harm. It's critical that our maps be as accurate as possible."

Reinertson said the new digital maps will help FEMA and Ecology:

  • Tackle the mapping needs of communities with growing populations and high-flood risks in coastal and levee areas.
  • Conduct a baseline flood risk assessment for all river drainage basins in the state.
  • Ensure that plans designed to offset the effects of flood plain development are properly evaluated and provide a sound basis for any improvements to be put in place.
  • Enable coordinated flood risk management activities between local, state and federal agencies.    

"The new digital maps are a vast improvement over the old paper maps," Sokol said. "They will be more comprehensive, show more on-the-ground information, and be more accessible to citizens and officials who need the information."

FEMA had planned to update the flood hazard maps in all 39 Washington counties. The federal agency was going to convert its existing paper maps into electronic format. However, FEMA changed its policy after the public raised concerns that high-risk areas needed improved, more accurate hazard maps.