New plan crafted to limit Ocean Beach erosion OCEAN BEACH Ocean Beach: Think tank devising ways to deal with erosion that's not a matter of if, but when

The Westside Transport Box, stretches out to the Pacific Ocean along Ocean Beach near Sloat Blvd. in San Francisco, Ca., on Thursday April 5, 2012. Ocean Beach draws more than 300,000 surfers, cyclists and visitors annually, making it one of San Francisco's most beloved natural open spaces. It will also be the city's first real test in responding to the effects of climate change. By 2050, the sea level will rise 14 inches, meaning the coast and the major wastewater and stormwater infrstructure embedded into it will be seriously eroded. A new plan from the San Francisco Planning Urban and Research Association, the final version of which will be released in April, lays out a long-term vision for the area. less The Westside Transport Box, stretches out to the Pacific Ocean along Ocean Beach near Sloat Blvd. in San Francisco, Ca., on Thursday April 5, 2012. Ocean Beach draws more than 300,000 surfers, cyclists and ... more Photo: Michael Macor, The Chronicle Photo: Michael Macor, The Chronicle Image 1 of / 9 Caption Close New plan crafted to limit Ocean Beach erosion 1 / 9 Back to Gallery

The silver tide that surges through Ocean Beach from dawn to dusk is a surfer's delight. For San Francisco, however, it is an unrelenting test of nature.

The 3.5-mile shore that lines the city's western edge draws more than 300,000 visitors annually. More shrouded in fog than in sun, it is not a postcard-perfect stretch of sand. But its condition has worsened for years as waves - heightened by climate change - hammer at bluffs, parking lots and the Great Highway.

A new, nonbinding plan by the San Francisco Planning and Urban Research Association, a public-policy think tank, proposes solutions to a problem that will only intensify if, as expected, sea level rises 14 inches by 2050.

Whatever long-term action the city takes will be costly and watched by other coastal communities grappling with the same challenge.

"Change is coming whether we like it or not, so it's not possible to keep things the way they were or go back to how things were in the recent past," said Benjamin Grant, a project manager with SPUR, which began a study two years ago and will finalize the plan this month.

"We're really faced with a sort of crisis point," he said.

Environmentalists have long criticized the city for managing the erosion on an emergency basis. In the winter of 2009-10, powerful storms battered away as much as 40 feet of the bluffs on the south end of the beach. Asphalt chunks from the overhead parking lot crumbled into the sea. Southbound lanes on the Great Highway were closed for much of the year.

A management challenge

The city responded by piling 425 feet of boulders in front of the bluffs, similar to what it did during storms in 1997. It was an attempt to prevent erosion and protect the city's wastewater and storm water infrastructure, which runs along the coast to a $220 million wastewater treatment plant.

Last summer, the California Coastal Commission unanimously denied the city a permit application to retroactively place rocks there. The California Coastal Protection Network, an advocacy group, sued the city.

"Not only are they illegal, unpermitted and have no engineering, they don't work and they actually exacerbate erosion," said Mark Massara, an attorney for the group, who says the city has violated state coastal laws for years.

A solution has remained elusive, in part because of the alphabet soup of agencies that oversee Ocean Beach. The beach, dunes and promenades mostly fall under the Golden Gate National Recreation Area. The Great Highway, trail and most parking lots belong to the city's Recreation and Park Department. The Department of Public Works performs maintenance and emergency repairs, while the Public Utilities Commission manages the sewage system and the wastewater treatment plant.

"No agency is charged with the overall health and future of the place," Grant said. 'They're all responsible for different aspects."

The U.S. Army Corps of Engineers is considering building a system that would pump 300,000 yards of dredged sand from channels by the Golden Gate Bridge to the erosion zone. The effort would "bury the existing rocks out there and construct a sand dune which would resemble other sand dunes out there," said Peter Mull, project manager for the corps.

But this approach, which could cost $5 million to $8 million, would last at most five years. "If there's an El Niño five minutes after ... it's most likely going to be gone," Mull said.

SPUR is calling to replace the tons of rocks with a low wall covered in small stones, which would shield a tunnel that carries wastewater under the road.

In addition, the Great Highway would be closed south of Sloat Boulevard, rerouted behind the San Francisco Zoo and narrowed from four lanes total to two. A coastal trail would replace it, allowing erosion to move inland.

Costly solutions

These solutions would be costly. Protecting the tunnel would cost $60 million, according to preliminary estimates from SPUR. Moving and shrinking the Great Highway would cost $30 million.

In all, SPUR recommends an estimated $343 million worth of changes, which include restoring the sand dunes, connecting Golden Gate Park with the beach and adding bicycle- and pedestrian-friendly features.

But it's unclear which, if any, recommendations the city will follow.

Michael Carlin, deputy general manager of the Public Utilities Commission, said the process was not far enough along for his agency to commit to any changes.

How the city responds will be closely watched, Grant said.

"Coastal communities, and in particular beaches up and down the coast, all over the world," he said, "are going to be faced with the question of, 'How do we respond to these forces?' "