Sea Level Rise and Coastal Flood Risk Assessment: Island County

In 2016, the Lead Entity for Salmon Recovery program partnered with the Island Local Integrating Organization (ILIO) to commission a report that would inform our restoration plans. To make wise decisions about the use of grant funds on restoration projects, our committees needed information on how sea level rise and storm surges may impact where and how we develop restoration projects. 

The University of Washington's Sea Grant program's Dr. Ian Miller modeled the potential future sea level rise and storm surge amounts by using Puget Sound-specific sea level rise projections, local tide gauge history, and measurements of Island County's land rise/fall (tectonic action). Adaptation International was involved in translating that data into maps for 5 areas around Island County.

The result was 2 tables that detailed theoretic levels of sea level rise and storm surge. The level of risk could be chosen for a given year to produce the projected increase in water level.  For example, if a culvert was proposed for replacement, the committees could look 50 years into the future, assume a 99% probability of likelihood and get the number 0.6 ft above the current mean high water. The committee could then decide if the design of the project was sustainable or not. 

This report was a pilot for a larger, Puget Sound-wide modeling effort named the Washington Coastal Resilience Project. See the link on the right for more information.

Things to remember when looking at this report and the maps:

1. This is a best-case scenario and projected levels may be conservative. 

2. The models used did not account for wave runup.

3. The 5 areas chosen for the maps were chosen because of their low topography, because of their potential for restoration efforts being focused there and because they represent 5 different geographic areas around Island County.

4. This report is to help make informed decisions and is NOT regulatory. The areas that are susceptible to future flooding already flood on occasion. There are no surprises here. 



Crockett Lake

Useless Bay

Crescent Harbor

Moran Beach