Agency’s monitoring program records changes from erosion at various coastal locations since 2022
Sept. 10, 2023 12:13 PM PT
San Diego County’s beaches need costly, sustained replenishment efforts to remain the wide, sandy tourist attractions they have been for so long, a new regional study shows.
Shorelines in south Oceanside, south Carlsbad, Leucadia and Coronado are shrinking fast, according to the 2023 “State of the Coast” report released Thursday by the San Diego Association of Governments.
Only beaches bolstered by sand dredged from nearby lagoons, harbors and offshore deposits are maintaining their width or growing, says the report, presented Thursday at a meeting of SANDAG’s Shoreline Preservation Working Group.
Most California beaches have never been the wide, sandy expanses seen in East Coast states such as Florida, some experts say. Most of the West Coast shore is steep, rocky and pounded by powerful waves, and the beach culture popularized by movies and advertising is largely a myth.
“Beaches are the essence of California and provide its most important aesthetic and recreational asset,” oceanographer Reinhard Flick of Scripps Institution of Oceanography wrote in 1993 in his paper called “The Myth and Reality of Southern California Beaches.”
“Yet the widest sand beaches in Southern California have been created and are maintained by human activity,” said Flick, who today is an advisory member of the SANDAG working group.
People have dumped massive amounts of sand along the coast over the years and built groins, jetties and breakwaters to keep it there.
The California Coastal Commission, established by voters in 1972, discourages the construction of groins and other hard retention devices along the coast because, while they may hold sand in one spot, they contribute to erosion elsewhere. But the commission continues to promote and sometimes requires sand placement projects.
Human activity also is a factor in beach losses. Upstream development from river dams to parking lots stops the downstream flow of sediment. Coastal construction, such as homes and highways, prevents the natural erosion of cliffs and bluffs that contributes to beach growth.
SANDAG has led two regional projects that placed sand on multiple locations along the county’s coast. Those efforts were 11 years apart, and the most recent was more than a decade ago.
“After each of the regional beach projects we had gains, but they are only sustained for a couple years,” said said Greg Hearon of the environmental consulting firm Coastal Frontiers, who helped prepare the SANDAG report.
“It will get more critical as sea-level rise accelerates.”
— Oceanographer Reinhard Flick of Scripps Institution of Oceanography
The first project, completed in 2001, placed 2.2 million cubic yards of sand, primarily from the San Diego harbor, on beaches the length of the county. It cost $18 million, of which 60 percent was funded by federal grants and 40 percent by state grants.
A second regional effort, completed in 2012, placed 1.4 million cubic yards of sand pumped from offshore deposits on beaches at a cost of $26 million. The state paid for 85 percent of that project, with the local jurisdictions contributing 15 percent.
SANDAG recently began studies for a proposed third regional project, which is several years away and could cost close to $40 million.
Smaller-scale projects have benefited beaches in several places along the county’s coast, but the gains can be fleeting.
Beaches in Oceanside, south Carlsbad, Leucadia and Coronado lost an average of 2 feet or more in width annually over the past 22 years, a new report shows.
Oceanside’s harbor entrance is dredged annually for navigation by the U.S. Army Corps of Engineers, which provides sand to maintain the city beach nearest the harbor. However, the sediment is fine-grained and washes away quickly, and there’s not enough to spread very far south.
Northern Carlsbad beaches get sand from the occasional dredging of Agua Hedionda Lagoon, which for years was kept open by San Diego Gas & Electric Co. to provide cooling water for the Encina power plant. Now the operators of the Carlsbad desalination plant dredge the lagoon.
Carlsbad has almost 7 miles of shoreline, though, and beaches at the southern end, in the Ponto area, are suffering. The average width there is 88 feet, which is worrisome, Hearon said.
Winter storms erode Southern California beaches, while the steady waves and long-shore currents of summer help to restore the sand and build them back up.
“South Carlsbad just seems to be one (place) that doesn’t hang onto anything,” Hearon said. “Going into a winter with a beach less than 100 feet should get your attention.”
Encinitas and Solana Beach got a big dose of sand from the restoration of the San Elijo Lagoon in 2018. Excavated material was used to create the county’s first “living shoreline” dune system at the nearby beach.
The experimental program added 8 acres of dunes covering a base of rock riprap and cobble, and planted with native vegetation for stability. As a result, the beach at Cardiff in southern Encinitas added 4.5 feet in width, and Solana Beach, immediately to the south, added 5 feet.
Encinitas and Solana Beach also are set to get sand from a new beach nourishment effort beginning this fall called the Army Corps of Engineers’ Coastal Storm Damage Reduction Project.
In development since 2000, it’s intended to continue periodic replenishment efforts in those two cities for the next 50 years. In 2015, the cost over the life of the project was estimated at $167 million. Last year federal officials allocated $32 million for the first phase of work.
Still, many San Diego County beaches continue to erode.
Oceanside’s shoreline lost an average of 2.3 feet in width at mean sea level each year from fall 2020 through fall 2022, according to the report.
At its best, Oceanside has 205 feet of beach at Windward Way near the harbor. The width shrinks quickly south of the city’s pier to just 18 feet at Buccaneer Beach and 15 feet at St. Malo. At high tide, the surf crashes on rock revetments protecting seaside homes in most of south Oceanside.
Coronado’s Silver Strand lost the most width of all, an average of 3.8 feet per year. However, Coronado has sand to spare, and still measured 686 feet wide in 2022.
Other beaches monitored for the report remained relatively stable or had slightly increasing amounts of sand.
Some people suggested more data points be included in the shoreline monitoring project, which includes little information from the shoreline along the city of San Diego.
“There’s a lot of erosion in Tourmaline (near Mission Bay) and Point Loma, but you guys don’t collect information there,” said Katheryn Rhodes. “These are really important areas that need monitoring.”
SANDAG plans to expand the program by allowing the public to go online and contribute their own photographs and observations to the database.
Flick, the oceanographer, said climate change increases the importance of monitoring beach erosion.
“It will get more critical as sea-level rise accelerates,” Flick said.
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