Butterfly-shaped reef proposed for Oceanside sand retention project

A butterfly-shaped scale model of an artificial reef built at an indoor wave pool in Oregon is helping to win support for Oceanside’s proposed Re:Beach sand replenishment project.

The experiments at Oregon State University’s research laboratory are the latest development in Oceanside’s unique effort to restore and keep the natural resource that contributes so much to the region’s economy and lifestyle and could serve as a model for other coastal areas nationwide.

“It’s going to help the beach,” said Reinhard Flick, an oceanographer with decades of experience on the staff of the Scripps Institution of Oceanography and with the California State Parks Department.

“There is no question that these things work to retain sand,” Flick said Monday. “It’s a matter of degree. This will be monitored and potentially modified … everybody’s going to be watching.”

Two groups of Oceanside residents and elected officials visited the Oregon laboratory earlier this year to see the design and studies underway.

“This model is the next best thing to building the reef in the ocean,” said state Sen. Catherine Blakespear, after visiting the research laboratory with local officials in February. “The work will help finalize a design that brings sand back to Oceanside's shoreline and strengthens our coast for generations to come.”

Also on Blakespear’s trip to the O.H. Hinsdale Wave Research Laboratory were Oceanside City Manager Jonathan Borrego and Mayor Esther Sanchez.

“It was pretty fantastic,” Sanchez said, when the Oceanside City Council reviewed the reef plan April 22. “I really appreciated being able to be there and see it myself and ask questions.”

Members of the nonprofit Save Oceanside Sand made a separate visit to the Oregon research lab and also came away impressed.

The modeling “provides proof” that the project could preserve sand and improve surfing, said SOS CEO Bob Ashton at the City Council. “This is what deliberate and focused coastal engineering looks like.”

The 1:35 scale model was tested in a 160-by-87-foot wave pool with a shore shaped like the stretch of beach from Seagaze Drive to Wisconsin Avenue where the artificial reef would be installed.

“We looked at over 45 distinct reef shapes and narrowed them down,” said Daniel Dedina, the lead coastal engineer for the city’s Re:Beach consultant GHD. More than 1,000 simulations of waves of various sizes, shapes and angles were done during nine weeks of modeling from January through March.

The actual reef would be about 900 feet long and the same distance offshore. The insect-shaped rock structure would have two wide, wing-shaped ends connected by a narrower, 200-foot-long center section like a bridge. The idea is to protect the beach by deflecting waves from any direction and still create the peeling lines loved by Oceanside’s surfing community.

“Beyond beach protection, the reef could create new rocky marine habitat in an area that's currently mostly sand,” said Dan Kahl, the project engineer for GHD, in an emailed response to questions about the project.

“It's also unique in that surfing is explicitly considered in the design, with efforts being made to avoid degrading existing high quality surf areas,” Kahl said. “Potential downsides, such as localized changes in waves or sand movement, are also being carefully studied and would be adaptively managed.”

Testing simulated a range of conditions including typical seasonal waves, high-energy winter storms, long-period south swells, and varying tidal conditions. The waves were generated from multiple directions and water levels, according to a report presented to the City Council

The modeling showed that “the artificial reef reduced wave energy that directly reached the shoreline, particularly during higher-energy conditions, thereby decreasing erosion potential,” the report states.

The reef is one of three key components of the project. The other two components are the placement of up to 900,000 cubic yards of sand taken from nearby deposits in the ocean, and the construction of two artificial headlands to help keep the sand on the beach.

The 900,000 cubic yards to be placed on the beach is four to five times as much sand as the amount dredged annually from the Oceanside Harbor channel.

Most of the sand taken from the harbor each year goes onto the beach north of the Oceanside Municipal Pier. South of the pier, roughly two-thirds of the city’s coastline never gets the harbor sand and is eroded to rock walls except at low tide.

The proposed headlands, to be built at the ends of Tyson Street and Wisconsin Avenue, would help hold the sand in place. The headlands are a little like groins or jetties, but shorter and rounder.

“If you want a wider beach, you have to have retention and you have to have nourishment,” said Flick, the Scripps oceanographer.

Flick said he has little doubt the project would work.

One of the biggest obstacles could be obtaining construction funding, Flick said. Federal funding is becoming harder to obtain for agencies such as the Army Corps of Engineers, which oversees most regional sand projects and could be involved in Oceanside.

Construction costs have been estimated at $50 million or more for the Re:Beach project. So far, the city has spent more than $1 million in addition to a 2024 California Coastal Commission grant of more than $1.8 million to help pay for three years of baseline studies.

Oceanside’s project is special in a number of ways. One is that it’s the first in the state and probably the nation to combine a large replenishment project with building the hardscape components of headlands and a reef.

Another way is that so far the city is the lead agency. Most other sand projects in the region are led by an outside agency such as the U.S. Army Corps of Engineers or the San Diego Association of Governments.

SANDAG has completed two previous regional sand projects in the county, in 2001 and 2012, that blanketed coastlines from Oceanside to Imperial Beach. The agency has launched initial plans for a third project, its largest yet, but the results of that probably are years away.

More recently, in 2025, the Corps of Engineers completed the first phase of sand replenishment in Encinitas and Solana Beach that is intended to continue periodically for 50 years.

The Corps launched a similar project last year at San Clemente in Orange County, just north of Camp Pendleton.

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This story was originally published May 3, 2026 at 5:12 AM.