Environmentalists hope to turn the tide against use of sea walls

For years, San Francisco’s Ocean Beach has been under assault by such powerful surf that a fierce winter storm can scour away 25 feet of bluff in just days.

The startling pace of the erosion near the San Francisco Zoo has compelled the city to spend $5 million to shore up the crumbling bluffs. The strategy has been simple: drop huge rocks and mounds of sand to protect the nearby Great Highway and the sewer pipes underneath from being destroyed by the crashing waves.

But as the enormous rocks have piled up, adding to a jumble of concrete — chunks of curb and bits and pieces of gutters — from parking lots that have tumbled onto the shore, so too have the demands that the city get rid of it all and let the coastline retreat naturally.

Now, San Francisco finds itself under fire from environmentalists, who call the rock and rubble unsightly and harmful to the beach, and the California Coastal Commission, which regulates development along the state’s 1,100-mile coastline but has refused to sign off on the fortifications, some of which have sat on the shore for 15 years without its permission.