By Molly Lawrence

A confluence of events is changing the floodplain landscape in the Puget Sound. Even absent significant flooding like that experienced in Colorado, New York and New Orleans in the past few years, floodplains have become an ever more important and complicated feature in the physical and regulatory landscape in the Puget Sound region.

Aconfluence of events is changing the floodplain landscape in the Puget Sound. Even absent significant flooding like that experienced in Colorado, New York and New Orleans in the past few years, floodplains have become an ever more important and complicated feature in the physical and regulatory landscape in the Puget Sound region.

In prior years, floodplain effects were felt only by people living along one of the half dozen or so rivers in the region that flooded every few years. In the past 10 years, however, that has changed due to a confluence of virtually invisible events. The combination of updates to the FEMA floodplain maps, the development regulations applicable to floodplains, and the applicable insurance requirements have combined to change the landscape in ways that are as significant as a flood itself.

FEMA’s floodplain maps

Starting in the mid-2000s, the Federal Emergency Management Agency began a process of updating its flood insurance rate maps for communities in the Puget Sound region. Many of the existing floodplain maps had not been updated since the mid-1980s. The intent was to use more current data and methods to update the regions’ floodplain maps and make them available to everyone digitally on the Internet.

As part of its effort to update the floodplain maps, FEMA asked local communities to demonstrate, for the first time since the inception of the National Flood Insurance Program in 1968, that the levees along many of their rivers were strong enough to withstand a 100-year flood (technically, a flood that has a 1 percent chance of occurring in any year).

Most communities — in the Puget Sound region and around the country — were unable to provide the necessary documentation.

As a result, in 2010, FEMA issued new preliminary floodplain maps for King County...

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This is an excerpt of an article which originally appeared in the September 26, 2013 edition of the Seattle Daily Journal of Commerce. Read the full article here.