To assess the risk of sea level rise, Grays Harbor County mapped river channels

A pair of grants from the Washington State Department of Ecology will allow Grays Harbor County to determine which areas of the county are most at risk from the effects of future sea level rise and to map the movement of several river channels.

The state Environmental Agency announced on Oct. 19 the awarding of $3 million in competitive grants to 21 cities and counties across the state to help plan for riverbanks, lakes and marine areas. The Grays Harbor amount was $212,500, including $130,000 for a sea-level rise vulnerability assessment and $82,500 for mapping meanders and changes in river channels.

Jane Hewitt, chief planner for both Grays Harbor counties, said the assessment will inform future updates to the county’s Coastal Master Program, a state-mandated document that governs the protection and use of shorelines established by the Shoreline Management Act of 1972.

The most recent update to the program this year included several policies related to sea level rise, including restrictions on residential and transportation construction outside sea level rise zones. Information from a recently funded evaluation will provide a clearer picture of these areas.

“There is extensive work (on sea level rise) by a number of different scientific groups and environmental agencies,” Hewitt said. “A lot of it was focused on Puget Sound and not necessarily the outer coast. It’s important to have information about what’s going on here, rather than generalized data.”

Climate impact groups at the University of Washington and Oregon State University have modeled sea level rise in Washington due to climate change, predicting anywhere from one to three feet of increase by 2100 for the “high” emissions scenario and more dramatic levels. for “worst case scenario”. The latter university embarked on the “Grays Harbor Coastal Futures Project” in 2015 to increase the resilience of Grays Harbor to sea level rise, flooding and erosion.

The upcoming assessment will be specific to the planning department. Thanks to the latest sea level rise grant money, Grays Harbor County will hire a consultant to create computer spatial models for future saltwater inundation areas during high tides and stormwater. Along with information on freshwater flooding, input from tribes and scientists will use the models to create risk maps for projected scenarios in 2050 and 2100.

The assessment will identify public and private stakeholders at risk from rising tides and rivers. These stakeholders, including government and non-government organisations, business and industry and community or neighborhood groups, will have the opportunity to learn about the assessment and inform the planning process through online materials and a series of public workshops. A final report with findings and recommendations on sea level rise must be completed within the next two years based on grant deadlines.

Hewitt said the planning department may decide to seek additional grant funding to address information gaps identified in the study or to implement some of its recommendations. For example, Pacific County was awarded $157,000 for a “Phase 2” study of sea level rise through Ecology’s Competitive Shoreline Planning Grant Program.

Any city, county or town in Washington with a Shoreline master’s program is eligible to apply for funding. Kitsap County also received a planning grant related to sea level rise, as did the cities of Coupeville, Ilwaco and Port Townsend.

Chelan and Clallam counties received grants to map the movement of the river along with Grays Harbor. The Grays Harbor Coastal Master Plan limits development in the channel’s active migration zone — the area where major river channels are “reasonably anticipated” to meander naturally over time — but does not specifically define those boundaries.

The county plans to hire a consultant to create a definitive map of these river movement zones — which are prone to property damage due to hazards such as erosion, high water or woody debris — for the Chehalis, Satsop and Humptulips rivers.

Contact reporter Clayton Franke at 406-552-3917 or clayton.franke@thedailyworld.com.

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