Civil/Structural Engineering, Vashon, Washington, USA 206-463-5311
Ellisport Engineering Blog
New Coastal Flood Maps and Proposed Regs for Vashon-Maury Islands.


On Thursday, April 28, 2011, Steve Kicinski, PE and Eric Rice, PE attended an informational meeting at the Vashon High School Commons.  The topic was “New Coastal Flood Maps and Proposed Regulations for Vashon-Maury Islands”. 


Recently, waterfront homeowners have become aware that they are listed in a coastal floodplain.  Who knew that there could be flooding on an ocean?  This information relates to flooding that results from high tides, low pressure storm conditions, and storm-driven waves (it does not account for tsunamis).  Large remodels, re-financing, or new construction require consideration  of the house placement relative to the flood plain mapping.  The maps presented on April 28th now list flood plain elevations.


Years ago, a large number of waterfront property owners were caught in the wide net cast by FEMA, King County, and the Department of Natural Resources.  Previous flood plain maps had no numerical elevation assigned to the flood zone, only a general map showing approximate flood zone areas.  This meeting provided preliminary floodplain elevations for the full coastline of Vashon-Maury Islands.  Each waterfront property owner’s home is clearly shown relative to the floodplain designation.


The maps are termed preliminary so the public can comment on the maps, so reviewers can check the technical accuracy of the maps, and so the final map adoption process can be completed in approximately 2 years (2013).  If located in flood zones, homeowners will now have to spend approximately $400 per $100,000 of house valuation for flood insurance.  If extensive remodels or new construction are contemplated, there are special design requirements that must be followed: chief among them is that all floor framing supporting habitable living space must be elevated a minimum of 3’ above the mapped flood zone elevation for the house location. 


There is still much work to be done in reviewing, commenting, defining what it all means to homeowners, and what the cost impact will be.  Suffice it to say, it will be another cost of owning waterfront property.  For more information, you can contact us. 


Additional King County information can be found at the following links:


King County general website about flood control


Information brochures about floods/flooding


Vashon-Maury Island Coastal Flood Hazard Mapping

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