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Area Beaches’ Shifting Sands Need Solid Solutions : Environment: Army Corp of Engineers’ six-year study gives scientific and technical data cities need to stop coastal erosion.

TIMES STAFF WRITER

Human activities caused the erosion of some Southern California beaches to bare rocks, and it will take humans to solve the problem, a U.S. Army Corps of Engineers study concludes.

More sand needs to be hauled onto beaches, carefully planned barriers need to be built in key areas, and local governments must consider the effect of new coastal construction on erosion before granting permits, suggested Rep. Ron Packard (R-Oceanside) at a San Diego press conference Friday announcing the study’s completion.

“When I was dealing with it as the mayor of Carlsbad a decade ago, we were hoping that we could find a solution by changing the movement of the water and thus the movement of the sand,” Packard said. “But I think that these results are saying that it appears the solution is going to be replenishment, maybe dredging . . . not some miracle that we can manage the movement of the waves.”

Some of the worst erosion in the county has occurred in Oceanside, which is also the center of activism to solve it.

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The report doesn’t map out specific solutions for any of the 84 miles of beaches stretching from the international border to Dana Point in Orange County.

Instead, it gives coastal cities the scientific and technical data they need to stop local beach erosion without making it worse elsewhere, said Oceanside Mayor Lawrence M. Bagley. And that might mean some tough political decisions about seaside building, Bagley said.

“If a local jurisdiction is asked to issue a building permit adjacent to a bluff, we will have the information at least available to say yes or no, this is going to have a detrimental effect to this property if you do that,” Bagley said. “There will certainly continue to be, for the protection of property, some seawalls required. . . . But, before that, we are going to know what’s going to happen to the neighbor.

“So, though it’s not an easy solution, a political solution is definitely necessary because we are affecting the rights of people to build along the beach itself,” he said.

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The six-year federal study began in 1983, with the banner for funding carried by Packard. Public workshops on a preliminary draft report will be held in April, with a final report sent to Congress by May.

The San Diego Assn. of Governments will be asked to use the report to develop a proposed coastal preservation strategy for the county by July, Bagley said.

The Corps of Engineers hopes to gain federal and local funding for a similar coastal study soon for the coastline in Orange and Los Angeles counties. The study eventually would extend northward to include the entire California coast, said Col. Charles S. Thomas, district engineer in Los Angeles.

The South Coast study pulls together a large amount of information about the sources of beach sand and why it isn’t where it used to be.

It also offers assessments of local situations all down the coast:

* The most critical erosion problems in San Diego County are in the stretch from Oceanside to Solana Beach; on the oceanfront in Coronado and in Imperial Beach.

* There is a domino effect along the coast if new seawalls along the shore or barriers in the water suddenly reduce the amount of sand on a beach.

For instance, when development of the Oceanside Harbor and the Del Mar Boat Basin at Camp Pendleton reduced the amount of sand on Oceanside beaches, there was less to wash southward to Carlsbad, Oceanside and Solana Beach.

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* Along a 4-mile stretch of Imperial Beach, the shoreline is narrowing by about 5 feet per year. This compares to 2 feet per year at Encinitas and Leucadia.

* In Coronado, winter storms can narrow the beach by as much as 150 feet in just a few months. This is recovered in the summer, but the large difference makes it essential that the seasonal balance be carefully monitored, the report said.

It notes that, after moderate storm activity in 1985-86, Coronado’s beaches receded by an average of nearly 200 feet, with the worst erosion in the south.

* Mission Bay beaches eroded about 3 feet per year from 1960 to 1980 because of jetties and a dam on the San Diego River. That ended when officials began importing sand there in 1980.

* Beaches along Point Loma and from southern La Jolla to Del Mar are among the most stable in the county.

* In the small part of Orange County included in the study, the only eroded area is a 2-mile stretch just south of Dana Point Harbor. The reasons for that erosion need study, the report says.

The study says sandy beaches disappear because of an imbalance between the amount of sand washed onto beaches and the amount washed off by waves. These imbalances in Southern California stem largely from urban activities that have reduced available sand, it says.

Among them are damming of rivers and streams that once deluged the shoreline with sand; seawalls that prevent erosion of bluffs; and jetties and other man-made structures that prevent natural sand transport along the shore.

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The 1980s also were much stormier than the previous two decades, said Andrew L. Kadib, project manager for the corps.

This meant more sand washed out to sea by large waves, giving scientists a surprise as they looked for worst-case scenarios of beach erosion, Kadib said.

“We found out that some areas had considerable losses of beaches that were beyond whatever theoretically you could have estimated,” he said.

This would worsen if the global sea level continues rising at the same rate it has in recent years. This could raise the water level along the California coast by perhaps 8 inches over the next 50 years, the study says.

Col. Thomas emphasized that the corps is not going against the Bush administration position that there is no firm proof yet of the global warming known as the greenhouse effect.

“We didn’t try to look at the cause,” Thomas said. “It’s a simple projection that it looks like, if you are a planner who wants to take into account what’s happened in the past, it would (be) prudent that you consider a rise in sea level.”

The Corps of Engineers’ study carefully avoids advocating specific solutions to any of the beach erosion problems in San Diego County. That needs to come from local governments, Thomas said.

However, the report also hints at some of the possibilities that could be considered.

It documents that, when storms wash coastal sand out to sea, it winds up in submarine canyons just offshore. There are several such areas along San Diego’s shoreline, just past the surf line, where sand could be “borrowed” from depths of less than 90 feet, it says.

Onshore “borrow” sites also are listed, but Bagley, the Oceanside mayor, expressed doubts that they would be cost-effective.

“Six years ago we were involved in a project with the state and federal government to bring in from inland 2 million cubic yards of sand. And the cost of that was over $4 million,” Bagley said. “So that is very expensive. But I think we’re going to be reaching the conclusion that we’re going to have to go inland or offshore to replenish the sand.”

Already, sand from harbor dredging is placed along beaches, and Oceanside also has a system to pump sand from the harbor to the beach southward. But, even with these efforts, erosion has continued.

Another possibility is to construct groins, or sand-trapping structures at an angle to the shore. But these would have to be carefully planned so they wouldn’t harm adjacent areas, said Stephen Fine, chief of the coastal resources branch for the Corp of Engineers’ Los Angeles district.

Coastal Sand Flows A six-year study shows for the first time the annual sand flow patterns along the San DiegoCounty coast, illustrating why certain beaches are eroded and others aren’t. For instance,the Oceanside harbor and a boat basin at Camp Pendleton cut sand transport from the north, but at Oceanside the strong seaward wave action moves what little sand that arrives there out to sea. This in turn denudes beaches southward to Solana Beach, because there is so little sandavailable at Oceanside. Del Mar is spared because there is a balance between the amount of sand naturally deposited there and the wave’s energy. Source: San Diego Assocation of Governments


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