Driving south along the sand near Moonlight Beach in Encinitas last week, Capt. Larry Giles saw something surprising at the base of a thick pile of boulders, recently stripped of sand by a relentless string of winter storms and high surf.

"Wow. I never even knew that there was a seawall there," said Giles, who grew up in Encinitas and has been a lifeguard there for 20 years.

Up and down the North County coastline, the message is the same: Recent high tides and heavy rains have taken a deep bite out of beaches from Oceanside to Del Mar.

So far, coastal homes have survived the onslaught, but in Cardiff a 40-year-old lifeguard station has fallen victim to erosion; in Oceanside, a beach playground has been jeopardized.

"It's just gone down to bedrock in some areas," Giles said. "We haven't had that happen for several years now."

Oceanside Harbor and Beach Coordinator Frank Quan said the erosion along Oceanside's beaches this winter is the worst he's seen since he went to work for the city in 1980.

"I can't remember a year where it's been quite this bad," Quan said. He said all city beaches have been affected.

And with rainy El Nino conditions expected to persist into spring, the problem may worsen before it gets better.

Natural give and take

Sand is a valuable commodity for many reasons, experts say. It provides a buffer against ocean waves for all of the stuff man has built along the water's edge, as well as a chunk of ever-shifting real estate that is home to many species of birds, crabs and fish.

The width of local beaches can also directly affect the coffers of coastal cities. Tourists simply don't flock to a beach so narrow that there is no room to spread a blanket or build a castle.

Still, shorelines are in constant motion, with Mother Nature directing a cyclical process of building up beaches and then whittling them down.

Larger waves in the winter scour sand from beaches and deposit it just offshore in long berms. Smaller waves that arrive each summer serve to wash that sand back on to shore.

But Bob Guza, an oceanographer with Scripps Institution of Oceanography who studies wave action, said in winters such as this one, with consistently big surf, the process can be disrupted.

"When there are really big waves in winter, they can push the sand out so far that the little summer waves can't push it all the way back in," Guza said.

Just how much of the area's sand budget might be out of reach?

"No one really knows that. It's why we do sand monitoring at Scripps," Guza said.

Greg Hearon, a coastal engineer with Coastal Frontiers Corp., said last week that it's unlikely the sand washed back onto the beaches later this year will make up for what was lost in the winter storms. Coastal Frontiers oversees a sand-monitoring program for the San Diego Association of Governments (SANDAG.)

Pervasive problem

Going into the winter storm season, sand levels were down on beaches throughout San Diego County, said Rob Rundle, project manager for SANDAG. The agency divides the county's shoreline into three segments: northern, southern and central.

He said since then, the worst erosion has been in the southern segment ---- from the Mexican border to Coronado ---- and the northern segment, which stretches from Del Mar to Oceanside.

"The central segment is probably the most stable ---- Mission Beach and La Jolla Shores, where we typically have wide, sandy beaches," Rundle said.

In the southern section, Imperial Beach has fared the worst. In North County, Solana Beach and Encinitas tend to have the worst erosion, Rundle said.

SANDAG monitors beach erosion twice a year, once in October and again in the spring. However, it can take months to analyze the reports, so a clearer picture of this winter's erosion won't emerge soon.

The regional agency does more than just gauge the strength of the county's beaches. In 2001, it embarked on a massive sand replenishment program, spending $17.5 million to dump 2 million cubic yards of sand on local beaches.

Another round of replenishment is planned, but the project is still years away and some coastal cities have recently said they might not have the money to get the job done.

Some cities have additional options. Oceanside gets help each year from the Army Corps of Engineers, which dredges the Oceanside Harbor every April to keep it accessible to boats and dumps some of the sand on city beaches, Quan said.

And this year, Moonlight Beach in Encinitas received about 5,000 cubic yards of sand from Scripps Memorial Hospital, Encinitas, which is excavating part of its campus to build a parking garage.

Trouble spots

In Encinitas, three parts of Coast Highway 101 this winter have been particularly affected by erosion ---- one right near the Solana Beach city limits, and two about 200 yards north of that, Watt said.

The coastal bluffs that are home to North County's popular state campgrounds have faced significant erosion damage. A lifeguard control tower at San Elijo State Beach was condemned several weeks ago after wave action undercut the tower's base and its lower story developed cracks several inches wide. The state now is replacing the tower with a temporary structure.

San Elijo also lost several of its most popular southern end campsites because of bluff erosion, said Brian Ketterer, superintendent of the state's parklands in northern coastal San Diego County.

State officials also may soon close a popular coastal walk that's just north of the old lifeguard control tower at San Elijo, Ketterer added. In several spots, the supporting bluff beneath the paved walkway has been eaten away by wave action.

In Oceanside, waves were so strong near Hayes Street that they pushed cobblestones out of the ground, said Quan, the city's beach coordinator. He said a playground on the beach near the pier was nearly undermined by wave action and had to be protected with rip-rap, as did a beach shower near Seagaze Drive.

Further south, strong storms and high tides have damaged Coast Highway 101 on the southern edge of Encinitas

"We've had some washouts that we're repairing now," city Public Works Director Larry Watt said Thursday.

At South Carlsbad State Beach, a bluff collapse caused problems for an access road, while high winds damaged a ranger station roof.

Crews are also expanding the rip-rap shoreline protection near the mouth of Encinas Creek.

"With the high tide and high surf, they (waves) have overtopped the road several times," city transportation director Skip Hammann said Thursday.

The city is adding 250 feet of rocky material south of the Encinas Creek bridge. It's part of a planned bridge replacement project, which is causing the closure of the southbound lanes of Carlsbad Boulevard until May 28.

A half-dozen smaller slides are visible throughout Encinitas, though none has yet damaged any of the multimillion-dollar blufftop homes perched on the edge of the Pacific.

A bright side for surfers

While the shoreline has suffered from this winter's series of storms, not everyone is complaining.

Wave conditions have been wonderful, said longtime local surfers Bruce King and John "LJ" Richards.

"I've been surfing since 1953 ... I think it's the best winter I've ever seen," Richards said during a break in a Encinitas City Council meeting Wednesday night.

King, who started surfing in the early 1960s and has three times been president of the Swami's Surfing Association, said he wouldn't go quite that far.

"I don't think it's the best winter I've ever seen, but it's among the top five," he said.

Staff writer Ray Huard contributed to this story.