Humboldt grapples with sea level rise

Daniel Mintz
Mad River Union

HUMBOLDT – Humboldt County is stepping up its planning for sea level rise in the Humboldt Bay area and is pursuing creation of a multi-jurisdictional agency to deal with it.

​What was described at the September 3 Board of Supervisors meeting as the “huge implications” of sea level rise is motivating the county to form a Joint Powers Authority (JPA) with the City of Eureka and infrastructure agencies.

​According to a staff report, the Humboldt Bay region has the highest rate of relative sea level rise on the U.S. West Coast. As water elevation rises, land is subsiding due to tectonic activity and soil conditions.

​The county is eyeing a benchmark of three feet of sea level rise, which is projected to be reached in 2070 and perhaps as early as 2050 with king tides.

​Lands within the Humboldt Bay Area Plan – which encompasses 20 miles of coastline and 21,500 acres of unincorporated bay territory from the Mad River to Table Bluff/Hookton Road – will bear the impacts.  

​“Just with one meter of sea level rise, the banks of all the sloughs within the Humboldt Bay Area Plan would be over-topped,” said Planning Director John Ford.

​Sixty-two percent of the area’s agricultural lands, 32 percent of its industrial/commercial properties and 29 percent of its coastal-dependent industrial land would be inundated...

​Sixty-two percent of the area’s agricultural lands, 32 percent of its industrial/commercial properties and 29 percent of its coastal-dependent industrial land would be inundated, he continued, quoting from a sea level rise vulnerability report by hydrologist Aldaron Laird.

​Also, 17 percent of the area’s public facilities and 11 percent of its residential neighborhoods would be swamped.

​“Those are pretty staggering numbers,” Ford said.

​Also in the swath of sea level rise overspill is U.S. Highway 101, the Humboldt Bay power plant and its adjacent cache of stored radioactive waste, the community of King Salmon, the Humboldt Bay trail and miles of water and sewer lines.

Third District Supervisor Mike Wilson.

​The county is already planning its response. Work related to a $425,000 Adaptation Planning Grant from Caltrans is focusing on the Eureka Slough area and will wrap up next year.

​Environmental Services Manager Hank Seemann said the resulting plan will “bridge from studies and plans to implementation measures.”

​The work that will need to be done in the coastal zone is under the authority of the state’s Coastal Commission, which was briefed on the Humboldt Bay situation at its local meeting last month by Aldaron Laird.

​Ford told supervisors that the presentation had a striking effect on coastal commissioners, who were “a little bit overwhelmed.”

​He added, “My read of their body language was, ‘We didn’t realize that this would be happening in this measure in Humboldt County’ – I think the term that was used was that this really is ‘ground zero’ in terms of developing a model of what should be the response from around the state.”

​With multiple agencies – including the Coastal Commission – having hands in permitting response actions, the concept of a Joint Powers Authority emerged. “They didn’t want to leave it to a fragmented, piecemeal approach,” said Ford.

​Supervisors supported the idea of forming a JPA for sea level rise response planning and supervisors Estelle Fennell and Mike Wilson were appointed to an ad hoc committee to work on it.

​Wilson is a member of the Coastal Commission and he said Humboldt’s “frank discussions” of sea level rise are unique because the real estate value in other parts of the state “can be a deterrent” in assessing risk.

​He added effective policy development hinges on a united front on the cause of sea level rise. “Tracking greenhouse gases and preventing them from being created takes land use policies and that takes policy makers that believe that humans are responsible for this,” Wilson said. “I think we have to account for that and understand it and believe it to take action in those arenas.”

Supervisors directed planning staff to return at a future meeting with a presentation on forming a JPA and what Fennell described as “a strategy for moving forward.”

​The state is promoting what’s known as “natural shoreline infrastructure” as a means of protecting assets. Seemann noted that in areas with salt marshes, there’s much less erosion and damage to infrastructure like the bay’s railroad grades.

​“Then we can look just northward, to Arcata, and they have a large marsh plain that is providing enhanced protection to that segment of the bay trail and the highway,” he said.

​The marshes reduce the height and the energy of oncoming waves, he continued. He said a grant proposal has been submitted to “develop a design and test the feasibility of creating new salt marsh” along a one-and-quarter mile segment of the bay trail south.

 

 







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