University of Washington climate researchers to evaluate the 2022 King Tide event

The University of Washington's Climate Impacts Group is doing an analysis of the record-breaking King Tide that flooded downtown last December.

At a Sea Level Rise Response Collaborative-Executive Committee meeting held March 3 Olympia Climate Program Director Dr. Pamela Braff said the group would look at the weather events and other factors contributing to the rising sea level.

According to Braff, the analysis will provide some context of future likelihood and how often it is expected to see a similar magnitude type of event in the future.

"There's some significant computer modeling that goes into evaluating that. It takes time. They run many scenarios, but they are working on that," Braff told the committee members.

Rich Hoey, Olympia's assistant city manager, recalled the tide predicted was 16.63 feet.

"[But] the tide came in 1.77 feet higher than predicted," Hoey said, adding that the actual high tide was 18.4 feet on December 27.

Hoey said the lowest-lying shorelines in downtown are built to a tidal elevation of 18 feet, and they had to close Fourth Avenue, the main east-west corridor downtown. They also saw significant flooding on Columbia Street, Capitol Way near the Farmers Market, and some challenges by Moxley Creek in East Bay.

"The main issue that we were focused on was marine water getting into our roadways flowing into the combined sewer system and causing significant problems for the LOTT treatment plant in terms of increase flows," Hoey said.

He added that they deployed catch basin covers to protect the LOTT plant and eventually filled the entire roadway.

Eric Christensen, former Olympia Water Resources director, said the event had exceeded Federal Emergency Management Agency's (FEMA) base flood elevation by almost five inches.

"This was greater than a 100-year event, based on their most recent mapping,” Christensen said, who was invited to the committee meeting to give additional input on the King tide event despite retiring in December.

"I think with La Niña events and atmospheric conditions, there would be an increase in the number of these high tides higher than expected," said Christensen, responding to Port of Olympia Commissioner Bob Iyall's inquiry about the predictability of the same event likely happening.

In the previous meetings, Christensen said downtown is most vulnerable to flooding from Capitol Lake. "We have responded there many times. But this is the first time we have seen marine flooding come over the shoreline. It was a new experience and a new response for us."

Christensen said the half-mile-long shoreline at Percival Landing is not easy to protect with sandbags temporarily.

"We need a permanent structure there to do that,” Christensen explained.

Christensen reiterated the plan he presented in the previous Sea Level Rise Executive Committee meetings, wherein he discussed proposals for benches, planters, and floodgates.

"One of the other key things is we need to improve our communications with the citizens to get the news out that this is going to happen," he said.