Natural Alternatives May Protect Highway 101 Along North Coast

CalTrans Considers Flood Options Along Major Highway

A portion of U.S. Highway 101 in the North Coast region of California is facing threats of flooding from rising sea levels. One method of protecting highways from coastal erosion is called “hard armoring” and consists of the use of riprap.  Riprap is an erosion protection method that requires the construction of a permanent layer of large, angular boulders, stones, and/or cobbles. The rock layer is designed to stabilize and armor the surface from erosion in areas experiencing a concentrated wave or flow energy.

A Natural Approach is Suggested

The Climate Change Adaptation branch chief for CalTrans has put forth the idea to plant a “natural shoreline” in lieu of the hard armor option. Though the concept has not been tried and tested, it is theorized that it may help the highway deflect or absorb rising waves. Given that it has not been proven successful, the natural approach faces odds against obtaining approval from the State.

Highway 101 Faces Erosion as Sea Levels Rise

A recent workshop was held by Caltrans where the living shoreline concept seemed to have been seriously considered. One thing that was definitely not on the table as a current option is relocating the entire highway to a more inland location. The agency is intent on keeping the current road alignment along Humboldt Bay. Relocating the highway would require moving communities and, at this juncture, is far too cost-prohibitive.

CalTrans is Keeping its Options Open

In an effort to keep Highway 101 from drowning, CalTrans is welcoming any and all suggestions between now and Spring 2022, when the agency is scheduled to have its reports prepared. The reports will include the option of alternative methods and will be based on analysis of geohazards, roadway designs, and other engineering considerations. 

Approximately 65 participants attended the recent online workshop, including the Third District County Supervisor and a Eureka City Councilmember. Plenty of questions were asked and discussed, but no solutions were reached. That is not surprising, given the implications of a major California highway facing wetland inundation.

Watch the YouTube video. The drone footage below shows the beauty of the North Coast along Highway 101.

The Date for a Final Plan

CalTrans has until December of 2025 to come up with a final plan for addressing the rise in the sea level on the 101 corridors near Eureka/Arcata. That date may be moved up if the roadway begins to flood at least four times a year. Any increased wetland inundation would trigger an accelerated process.

The Process of Relocating a Highway

Although moving the highway inland is not a current option in the North Coast area, it has been done before in California. In 2017, nearly three miles of Highway 1 in San Luis Obispo County was relocated inland due to coastal erosion. The huge project required agreements with nongovernmental organizations and private landowners. The California Coastal Commission also required mitigation of the ecological impact of the construction as a condition of the project. The mitigation was accomplished by the restoration of more than eight acres of coastal wetland and more than 20 acres of coastal prairie.

North Coast Personal Injury Lawyer

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Photo: by Georg Eiermann via Unsplash

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