July 15, 2022
Still rising: Planners assess sea level, storm surge risks
Kai Uyehara

Closer to the edge: Designs for erosion control and repair at Bellingham’s Boulevard Park will be worked into other future projects in shoreline areas vulnerable to inundation by rising sea levels and damage from powerful storm surges. (Amy Nelson photo © 2022)

July 15, 2022
Still rising: Planners assess sea level, storm surge risks
Kai Uyehara

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Warm summer nights, a Super Moon and the lowest tides in a decade have shifted the threats of climate change and sea level rise to the back burner for some — but not local planners working with last winter’s rising sea levels and storm surges that combined to flood low-lying areas of parks such as Bellingham’s Boulevard Park.

Water levels of the future, fed by glaciers melting as global temperatures rise, are forecasted to rise 13.5 inches at Cherry Point and 13.92 inches at Friday Harbor above 2016 levels by 2050. Combined with high tides and storm surges, the lower reaches of shorelands, estuaries and aquifers — including areas on which homes, businesses, parks and railroad tracks now stand — will meet the Salish Sea.

To meet the rising tide, local planners have been working with the United States Geologic Survey and its Puget Sound Coastal Storm Modeling System (CoSMoS) to model rising sea levels in extreme weather conditions and anticipate the effects and adapt future design of infrastructure.

The CoSMoS model shows extreme flooding condition scenarios such as a one-meter rise in sea level as well as a one-and-a-half-meter rise which are both worst case scenarios, said Steve Sundin, environmental city planner for Bellingham.

White tarps covering dredge spoils on the Bellingham Bay shoreline mark the area which will one day become Cornwall Beach Park. Designs for the park will incorporate data from the CoSMoS storm surge model. (Kai Uyehara photo © 2022)

Each jurisdiction is applying information gathered from the generated model to see what is vulnerable in flood scenarios, said Sundin. Jurisdictions will then analyze risks, such as exposure of buried sewer pipes, and produce an adaptation plan to guide planning and infrastructure that could be affected by future floods.

“I think we’re starting to get ahead of [increasing water levels] with the effort that we’ve put into it locally,” said Kurt Baumgarten, environmental planner for the Port of Bellingham. “We’re starting to integrate that information into projects at this point.”

In the city of Anacortes, the city council has already moved forward, passing an ordinance this week increasing to two feet the height new construction must be built over the base flood elevation that would be hit during a flood.

Park … underwater

Among Bellingham’s early-stage projects are Boulevard Park, the expansion of treatment plants and the creation of the Cornwall Beach Park. 

Boulevard Park, located between Fairhaven and downtown, was built by filling the open waters of Bellingham Bay before there was any understanding of sea level rise, said Gina Austin, project engineer for the Bellingham Parks and Recreation Department. Some areas of the park sit below the projected sea level rise modeled by CoSMoS, but there are other areas such as the Woods Coffee shop that are above these levels because they rest on the original shoreline. 

 “If you have a storm or a high tide, that’s where we start to get into problems,” Austin said. Boulevard Park is also suffering from erosion that will get worse if the park is not protected from large storm surges which are happening at least once every other year.

Erosion is occurring along the shoreline on the south beach between Woods Coffee and the over-water walkway, Austin said. Topsoil is sitting at the water’s edge and a revetment of large angular rocks is coming undone and chunks of the shoreline have fallen into the waterway.

High winter tides frequently flood the north end of Boulevard Park, making for a wet stroll — and shoreline erosion. (Amy Nelson photo © 2021)

CoSMoS modeling shows that higher elevation areas of the park such as where the coffee shop, the playground and the parking lot sit above a one- to one-and-a-half-meter sea level rise, Sundin said., A one-meter rise would inundate the outer edge of the park where the rock revetment protects the west beach, and a one-and-a-half-meter rise would flood nearly the rest of the unelevated park. A storm surge on top of these worst-case scenario increases would compound the flooding.

Austin said erosion at Boulevard Park has put the park at the top of the Bellingham Parks and Recreation Department’s priority list. The north side of the park sits below the CoSMoS’ projected sea level rise and already suffers flooding during winter storm surges. 

Work on the north beach may begin in 2024, said Austin. Modeling data will be incorporated into designing a remedy to adapt to rising sea levels. The north end of the park may be raised to protect against energy and rising water due to storms. Floods can occur on the north end, but the  north and west beaches’ shorelines process elevated waters naturally – a design the south beach could benefit from to adapt to high tides and storm surges.

Park-goers currently see a temporary orange construction fence on the south beach work designing the new beach is ongoing. Large scattered rocks will be removed and smaller rocks and sand will fill the shoreline to mimic a natural beach and create a natural grade where storm surges will dissipate on smaller materials, Austin said.

Building the future on data

“I think the important thing is that we are using this model now to inform any type of capital facility planning that we’re working on,” Sundin said, “so we use these scenarios for things that we know we’re going to build in the next five to 10 years.”

To the north, the future Cornwall Beach Park will benefit from the information, when the park is completed in about three years, Sundin said.

What features are put in the park, how much land is filled in, and how much armor and stabilization the park needs are all factored in using CoSMoS information, Sundin said.

The County, City and Port are just beginning to examine the data garnered by the model, as each jurisdiction works towards their own risk assessments and adaptation plans. 

Even if planners may feel confident they’re ahead of the curve in anticipating rising sea levels, Sundin said they must plan as if flooding were a 100% certainty. “Any capital facility planning that we do, or any projects that we want to undertake, we should be thinking about the worst-case scenario”

By next year, the city plans to have a sea level rise risk assessment to present to the public for discussion. 

— Reported by Kai Uyehara

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photo: Amy Nelson © 2022
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