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New study highlights speed of Pacifica’s erosion

Posted on August 22, 2022

Rising sea levels are eating away the California coast, and a recent study found that the cliffs in Pacifica are among those crumbling the fastest.

The study, published by Scripps Institution of Oceanography at the University of California, San Diego, used data of cliff erosion between 2009-2011 and 2016 along 538 miles of California’s 1,023-mile-long coast. Statewide, cliffs eroded an average of 2 inches over the period.

Cliffs in Pacifica and the San Mateo County Midcoast beaches including Martin’s Beach south of Half Moon Bay, were deemed hot spots, having eroded more than 16 feet per year. The highest rates of erosion were found in Northern California locales with more rainfall and larger waves near Humboldt Bay and Del Norte County.

The scientists used laser-imaging technology to measure both cliff-top changes and changes within the cliff face.

The study adds to a previous one conducted with data from 1998 and 2009-2010. Data collection began last year for the study’s third iteration.

“We need to survey the coast more frequently so we can better track how the coast is evolving and improve model predictions,” said one of the study’s co-authors, Adam Young, in a press release.

The threat of erosion is nothing new to cliffside Pacificans. In the late 1990s, heavy El Nino storms led to the condemnation and demolition of a dozen homes as the ground beneath their foundations fell into the ocean.

Again in 2016, after another round of El Nino storms, Pacifica made national headlines when seawalls gave out and residents of cliffside apartments were evacuated when their backyards fell into the ocean. The state awarded $7.75 million to design and construct stabilization measures at the site, though the California Coastal Conservancy has been slow to authorize the project, said Director of Public Works Lisa Peterson. In the meantime, a temporary rock revetment was constructed to stabilize the cliff.

City engineers are trying to stay ahead of the crumbling coast. The city is in the scoping phase of its Beach Boulevard Infrastructure Resiliency Project. The seawall along Beach Boulevard was originally constructed in 1984 and has experienced failures in multiple spots.

Twelve percent of Pacifica’s structures, most of the city’s more affordable housing and more than half of its businesses are in the coastal zone west of Highway 1.

Late last year, the state Assembly voted to pass a “managed retreat” bill that would help California coastal communities adapt to the eroding coastline. The bill allowed the state to buy homes vulnerable to future erosion and rent them out until they were, inevitably, deemed too dangerously close to falling into the ocean and torn down.

Gov. Gavin Newsom vetoed the bill, however, saying the strategy alone did not “comprehensively address the costly activities envisioned, likely to be carried out over decades.”

Pacifica rejected the California Coastal Commission’s recommendation to add managed retreat to its planning strategy. When the city revisited its Local Coastal Plan in 2018, Pacifica residents demanded the removal of the phrase “managed retreat” from the plan. People fear its impact on their ability to insure and sell their homes.

Pacificans exchange the risk for the reward of views and recreation. Stephanie Hamilton lived on Beach Boulevard for 15 years. She noticed the ocean creeping closer, slowly but surely, flooding her garage with increasing frequency.

“It’s not for the faint of heart,” said Hamilton. “But it is stunning and beautiful.”


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