In Pacifica, beachfront properties and houses on worn-down cliffs are devalued and could ultimately be destroyed by flooding and erosion. In Half Moon Bay, properties sit farther away from the ocean due to zoning that largely designates bluffs as open space. One thing the two cities have in common: As sea levels rise in San Mateo County, Highway 1, beaches, trails and important infrastructure are threatened. 

Both municipalities are in the process of revising their local coastal programs in response to sea level rise. Pacifica approved a draft to send to the California Coastal Commission on Monday. 

“We need to come together and start moving forward on this,” Coastal Commission Public Information Officer Noaki Schwartz said. “The situation has gotten pretty urgent.”

Kelsey Ducklow, a climate change analyst with the Coastal Commission, said the first step for many cities is conducting a vulnerability assessment. 

These assessments, backed by the best available science, look at how sea level rise could affect communities in the coming years. Juliette Finzi Hart, an oceanographer with the U.S. Geological Survey, said  Our Coast Our Future flood maps used by both cities provide accurate projections of what would happen with certain sea level rise scenarios. 

“The thing that is the tricky part is when that one foot of sea level rise will happen,” she said. 

“That is completely dependent on greenhouse gas emissions, how the earth warms, all these different factors that we don’t make any claims on. We show you what could happen with a foot of sea level rise.”

Half Moon Bay’s vulnerability assessment found that flooding and erosion could affect beach access, the Coastal Trail, the wastewater treatment plant and roadways as early as 2050. 

The differences between Pacifica and Half Moon Bay are pronounced when it comes to residential property. Half Moon Bay’s vulnerability assessment found coastal flooding would only affect one home. Erosion may affect a handful more.

“Because of our high bluff conditions and most of our subdivisions being set back pretty far, there isn’t a whole lot of residential development that’s going to be vulnerable,” said the city of Half Moon Bay’s Associate Planner Brittney Cozzolino.

Erosion is a more profound concern in Pacifica. Seawalls have failed, and homes and apartments have been removed because of erosion. 

To address these problems, Ducklow described three categories for solutions: protection, accommodation and retreat. 

Protection involves protecting developments through structures like seawalls, Ducklow said. Accommodation strategies focus on adapting to changing water levels, which could include elevating structures. Retreat can mean relocating buildings and making development decisions to ensure properties are protected in the future. 

“There can be hybrid approaches,” Ducklow said. “Things are going to change over time. What one place does on one section of the shoreline might not be right on other sections of the shoreline.”

Half Moon Bay is considering strategies that include limiting development in hazardous areas, adjusting building codes and retrofitting structures. One retreat effort already underway is part of the Poplar Beach Gateway plan to relocate the Coastal Trail. 

Seawalls have long been used in Pacifica. According to the National Oceanic and Atmospheric Administration, armored shorelines can be beneficial to prevent beaches from moving inland, but it may hurt marine habitats and affect beach access.  

When the city of Pacifica floated the idea of incorporating managed retreat into its LCP, many homeowners fought against it. Now, the draft LCP says “the city has rejected managed retreat as a sea level rise adaptation policy in this LCP and managed retreat could only become the policy of the city subsequent to a future amendment to this LCP.”

But even as the plan heads to the Coastal Commission for review, the topic remains controversial. At Monday night’s meeting, a throng of speakers presented disparate views. Some called for removing all reference to managed retreat, while others argued the city shouldn’t try to fight nature. 

Coastal resilience policies that are in Pacifica’s draft LCP include beach nourishment and sand retention, seawalls, flood protection and updating the sea level rise adaptation plan every five years. 

In the decades to come, Californians will see how past decisions affect life in the 21st century and beyond. 

Cities like Half Moon Bay and Pacifica are already seeing these consequences and trying to prepare. 

“There’s a lot of fear out there for people who have homes or special places on the coast,” Bucklow said. “There’s misunderstanding about what planning means. The best thing to do is think through these things and plan for them.”

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