Case of the Vanishing Coastline : Beaches in Retreat as Man, Nature Take Their Toll

North County shrinks some days and grows on others.

It is usually a slow, nearly imperceptible change. Each day varying amounts of sand move north or south, in shore or off shore, causing subtle differences in the mass of real estate here.

Sometimes the changes are abrupt, like they were on March 25 in Encinitas when a large portion of the bluff collapsed, taking a retaining wall, wooden stairs and part of a walkway with it.

It’s the latest, but not the most dramatic example of bluff failure in North County. In the early ‘40s, the Golden Lotus Temple belonging to Self Realization Fellowship on the Cardiff/Encinitas border at Swami’s slid down the cliff.

Sandstone bluffs are typical along the North County coast. They fail when the top of the bluff becomes too heavy for its base, or when cracks allow large chunks of soil to loosen.

The greatest protection against bluff failure is a wide, sandy beach.

But wide, sandy beaches--once the norm in North County and a great natural attraction for residents and tourists--are disappearing.

The beaches have been in retreat for a number of years. Some beaches have become narrow; others are now covered with cobblestones rather than sand.

The beaches are victims of changing weather patterns and of human-engineered changes to the landscape.

A number of those studying the changing coastline predict that without significant intervention--by people or by nature--sandy beaches in North County may be endangered in as little as five years.

Beach sand is measured in plots known as littoral cells, which are stretches of coast with a rocky headland and source of sand at one end and a submarine canyon that catches sand at the other.

The Oceanside littoral cell stretches from Dana Point in Orange County to the La Jolla Submarine Canyon, and moves hundreds of thousands of cubic yards of sand around each year.

Sand is lost in the winter when the swell direction is normally from the north. Much of that sand returns in the summer when the swells move in the opposite direction. But some of the sand moved south in winter is washed into the underwater depths of Scripps and La Jolla canyons, from which it does not return.

The shifting of sand into offshore canyons has amounted to at least a 14-million-cubic-yard net loss over the last 50 years, according to David Skelly, a coast engineer for Scripps Institution of Oceanography. “The sand in those canyons is about 3 to 4 miles thick. We will continue to loose sand. The cliffs will erode further. Unless we do something, there won’t be a beach in North County in five years.”

New sand for the nourishment of beaches is generated primarily from two sources--rivers and cliffs. Day after day, the two sources deliver small amounts of new sand; during periods of heavy flooding in the past, large amounts of new sand have been deposited.

The erosive process is as old as the earth itself. But in relatively recent times, it has been disrupted.

The rivers have been dammed and mined; the flow in and out of lagoons has been blocked by roads and other development, and bluffs have been protected as valuable real estate. All of those actions have decreased the flow of sand and hindered the ability of the beaches to replenish themselves naturally.

Not all beaches have been depleted. The Oceanside area beaches still have a fair amount of sand, as do those in Solana Beach and Del Mar.

“I’ve seen about 2 feet (of sand) a night being deposited in Solana Beach recently,” said Andy O’Leary, captain of the Solana Beach Lifeguards. “Unfortunately, that does not seem to be the case from Seaside Reef and points south. There, the entire beach is gone, and there are cobbles in its place.

“I think that this is going to create a large strain on the beaches with sand this year. Everyone will be coming to the beaches that have sand on them.”

The presence of beach cobbles in North County is nothing new. The beaches between Oceanside and San Diego were primary sources of cobbles for grinding in California from 1919 to 1949. Ponto Beach in South Carlsbad was mined as a major source of the stones. Many of the streets in San Diego were built from beach cobbles gathered in the Del Mar area.

But since the early 1980s, the amount of beach dominated by the cobble has been increasing.

The cobbles wash ashore as the amount of sand on the beach decreases. The area starting at South Carlsbad and stretching to Solana Beach is now heavily cobbled.

At Encinitas, the beach known as Stone Steps is among those that have shifted from sand to cobble.

Beach cobbles are piled up against the cliff and at the foot of the stairway that allows access to the beach from the bluff. Like most public access stairs in the area, these have had to be rebuilt at the base several times because of the battering they take from waves and cobble.

Two decades ago, people played volleyball in the sand at Stone Steps.

Even at low tide, the water reaches nearly to the base of the cliff, which has been undercut and runs concave at the base for many feet in some spots. Water drips from the bluff as from a leaky faucet. In some areas the water pours onto the beach in rivers. The water seepage--some of which is natural and some the result of activities such as lawn watering--accelerates cliff erosion.

On a recent warm and sunny day, the beach was vacant except for two men struggling over the cobbles. “I’m a bodysurfer,” one says, “and I’m afraid to go into the water because of all the stuff in it.” He holds up a rusty two foot iron bar to illustrate his point.

The bar he is holding is from one of the failed seawalls that line the cliffs throughout much of Encinitas. In some places the steel is scattered sparsely along with broken chunks of wood and concrete which have also fallen onto the beach.

One section, approximately 50 yards wide, has completely broken loose. Large chucks of sandstone, wooden beams and other debris are thrown along the cliff face.

Few question the value of beaches: they are beautiful to visit, prevent millions of dollars in property damage during storms, increase the value of real estate and support a huge recreational and tourist economy.

A number of scientists have studied North County’s changing coastline, but they don’t necessarily agree on what can be done to protect it.

Among those who believe that North County beaches can be nourished with sand from lagoons is marine geologist Gerry Kuhn of Ocean Sciences Research Institute. The institute is composed of geologists and marine archeologists who work with businesses and governments to counteract negative impact on the ocean environment.

“If not for the dredging of the Oceanside Harbor and Agua Hedionda Lagoon (in Carlsbad), we would have had the erosion problems we’re facing now in the ‘60s,” Kuhn said. “The sand from the dredging of Agua Hedionda in ’53 and ’54 when the SDG&E; plant was built there displaced 5-million cubic yards of sand, enough to create a beach 400 feet wide. A lot of that sand flowed south and north and nourished the beaches of North County for years.”

The California Coastal Commission voted March 12 to allow the City of Carlsbad to dredge more than 3.7-million cubic yards of sediment from Batiquitos Lagoon. The project in the 600-acre wetlands is expected to begin next year. The federal government and some environmental groups had backed a less ambitious plan that would have moved less sediment and created less change in the lagoon.

The sediment dredged from Batiquitos will be channeled to the surrounding beaches and two permanent jetties at the mouth of the lagoon will be constructed.

“I don’t see anything but good coming from the dredging of the lagoon,” Kuhn said. “It will help the bird life, bring back fishing in the lagoon because it will be continually flushed, stop the bad odor and deposit tons of sand on the beach at Ponto. That sand will then be moved onto other North County beaches to the north and south.”

Skelly, the coast engineer from Scripps, agrees on the need to identify a new source of sand, but has a different idea on where that sand should come from.

The sand from lagoons provides only temporary nourishment for the beaches, he said. “The grain size of what is already on the beach is all that will stay. The finer stuff, which much of the lagoon consists of, will wash away.

“I think that we should be looking behind the dams where a great deal of sand is trapped. If we can get the sand over the dams, the storms will drive it down to the beach. This would also help slow stream bed erosion.”

Another way to replenish the beaches could be with the sand that has washed out to sea, Skelly said.

That sand mass is about four miles offshore at a depth of about 2,400 feet. The technology exists to lift the sand to barges and bring it back ashore, he said, although the process would consume a lot of energy.

Ultimately, without a broad, sandy beach, nature will use the cliffs to replenish the beach, Skelly said.

“The cliffs in Encinitas are in danger. Years ago there were several more blocks near Moonlight Beach. We haven’t had any really large surf recently, but if we would have had big surf during our high December tides of this year, it would have caused severe damage.”

Independently many North County communities have attempted to solve the problem of a dissolving coastline.

Millions of dollars have been spent both privately and publicly to keep the sea away from the cliffs and to help replenish the beaches. Some of the measures have managed temporarily to hold back the tide.

In Oceanside, a sand bypass system has been used to pump sand from the Oceanside Harbor onto the beaches. The system pumps a mixture of sand and water from the ocean floor in the harbor, and carries the sand through a pipeline where it is discharged on the beach at Tyson Street.

Carlsbad often pumps sand from the Agua Hedionda Lagoon onto a nearby beach. This effort has created a beach that usually lasts about one season. Another method employed by Carlsbad is the seawall. The wall, which was completed in May, 1987, stretches south from Ocean Avenue for about 1,000 feet, and was constructed at a cost of $4.1 million. To date there have been no reports of slides in this area.

Another seawall with an estimated cost of $3.5 million has been proposed in Carlsbad to protect the highway between the jetties at Tamarack and the warm-water jetty across the street from the SDG&E; power plant.

But many object to seawalls or doubt their long-term effectiveness. The seawalls trap the new sand that comes from the cliffs and there is concern about the aesthetic degradation caused when cement covers the bluffs.

Encinitas has dumped $40,000 worth of sand onto Moonlight Beach over the last three years. In addition, the city of Encinitas is considering the formation of a task force to study the problems of erosion and deal with them.

According to Monica Tuchscheer, associate planner in Del Mar, the Beach Preservation Initiative enacted in 1989 is meant to regulate use of the beach, to protect it and to remove non-complying structures.

On April 27, a wall built in front of a private home and extending onto the public beach at 19th Street in Del Mar was removed. Other walls that encroach on Del Mar’s public beach are slated for removal by 1993.

As possible remedies for beach and cliff erosion are debated on land, the sea remains constant in its give and take.

Recently, a 25-foot piece of a lumber schooner, believed to have been built in the late 1800s, washed ashore at Seaside Reef in Solana Beach. The piece has been moved to the San Diego Maritime Museum to be studied.

While the sea may one day give up more of what it has buried off the coast of North County, it has always swallowed more than it has returned. Sand is no exception.

Human engineering has kept the beaches from being replenished naturally, and, experts say, it will likely be needed again to restore them.

MORE ABOUT BEACH EROSION

More information concerning the erosion of the beaches and cliffs in North County can be acquired by writing to:

U.S. Army Corps of Engineers

Los Angeles District

Planning Division, Coastal Resources Branch

P.O. Box 2711

Los Angeles, CA 90053-2325

When writing, request:

Coastal Cliff Sediments,

San Diego Region,

Dana Point to The Mexican Border

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