City looks to living shoreline to protect residents from sea level rise

Plan to be finalized in February 2022

Last week, the city held its fourth public workshop for the dune and shoreline management plan, allowing the community’s feedback for a project that aims to mitigate sea level rise in Carpinteria.  

The goal of the dune and shoreline management project is to identify possible long-term funding sources for maintenance of a living shoreline. Living shorelines create a stabile coastline composed of natural materials, such as sand, rocks or plants. Through the workshops, city officials said they’re trying to provide resources and make residents aware of the impacts of sea level rise as well as implementing the dune and shoreline management project.

The current plan will tackle the next 25 to 50 years of coastline management, Erin Maker, Carpinteria environmental coordinator, said. The project is split into four areas: from the inlet to Ash Avenue, from Ash Avenue to Linden Avenue, from Linden Avenue to Carpinteria Creek, and from Carpinteria Creek to the tarpits. 

Maker said the team – composed of coastal engineer Chris Webb, dune designer/restoration ecologist Dave Hubbard, dune designer/restoration ecologist Matt James and deputy project manager Taylor Lane, along with Maker – is looking at a combination of strategies to incorporate into the design. This would include both hard structures and soft structures, such as beach nourishment, dune restoration, cobble and artificial reef, among others.   

Webb said the design would widen the beach by nourishing it, building and enhancing the dunes, looking at sediment sources, building a living shoreline and putting in a temporary pilot program groin – a structure that is perpendicular to the beach – near Linden Avenue. The model has been tested for several storm wave and water level situations. The team found that a single dune ridge of living shoreline with a wide beach is the best scenario offered for shoreline protection. 

“It still allowed water over it however, so it wasn’t completely without its shortcomings,” Webb said. 

Maker went over several key areas within Carpinteria that are vulnerable to sea level rise, including the downtown commercial corridor, the beach neighborhood and shorefront properties, and infrastructure such as roads, parks and utility lines, including the Highway 101. But she emphasized that the “unprotected, low-lying coastline” was the most vulnerable, which houses 41 affordable housing units and 213 campsites. 

“Linden Avenue is one of the primary routes to the coast from the beach neighborhood. So that’s really important for evacuation purposes. We don’t have any other routes that are accessible from the downtown neighborhood to the beach neighborhood in Carpinteria without walking,” she said. 

By 2100, the “reasonable worst case” for sea level rise within the city is five feet, according to Maker. 

“It can have some pretty significant impacts on property, including our transportation corridor (...) our coastal access,” Maker said during the meeting. 

Maker said that currently, the beach remains unprotected for the majority of the year, and that the beach is narrowing due to natural sediment flow blockage and recent sediment disposal activities. Current shoreline protections that exist include a rock revetment upcoast on county property and vegetated dunes on state parks property, as well as the city’s winter berm program. 

Maker provided attendees with a 1929 aerial photo of Carpinteria, showing wide, sandy beaches compared to the narrower ones currently in place. 

“What we’re trying to do with this project is mimic historic conditions,” Maker said. 

Maker said the team is planning on finishing the design in February 2022. 

Public attendees questioned administrative costs related to the plan and its funding. Maker said the team does not currently have estimated costs for the plan, which she said will be addressed in the future. 

Greg and Margaret Connors asked about the logistics of the groin on the beach. Greg said he grew up on Redondo Beach and said it was “ruined by groins.” Maker said the team wants to minimize any impact to the surrounding area and are taking that into account. 

In response to a question from Andrea Adams-Morden about maintenance of the beach, Webb said the idea is to minimize any maintenance that would need to be done.

“The dunes are able to sustain themselves over a long period of time. We’d rather not have to go in and do a lot of maintenance, and have the dunes just enlarge, increase, rise, change and shape in form,” Webb said.