Delete the Sea Walls

I ran into my neighbor Deirdre Harris at the laundromat last week, and learned that she's proofreading San Francisco.

"First I noticed them and thought they were odd, and I kept noticing them and then thought, "When you see one that was spelled right, you forget that humans were involved in making them,'" says Harris as we walk from curbside to curbside through the Haight toward Cole Valley during a "wash" cycle.

Harris, a local architect, has made a mission of seeking out and photographing copy-editing errors in the street names city workers press into the cement on San Francisco sidewalks. Stanyan at Haight, for instance, reads "Stayan" at Haight. South of Market, Fifth and Minna is "Bth" and Minna.(1)

Harris has so far collected 17 such errors, and she's going for more. Just last weekend, she says, "I took a walk over to my friend's in Pacific Heights and got seven more. When you see a mistake, you're reminded of the human hand and the things that humans do wrong."(2)

That's for sure. Take, for instance, the parking lot off the Great Highway to the west of Sloat Boulevard. Or the sewage transport box under the road near there. Or the rubble-pile sea walls along the south end of the beach. Or, for that matter, take the entire stretch of the Great Highway running from Point Lobos Avenue to Lake Merced. It's all a big, horrible mistake. It needs a copy editor desperately. But just as writers sometimes think their precious labors are set in cement, and battle fearlessly to preserve their crabbed prose, so do cities seek to protect even their least felicitous works.

Last month, in the days before a ferocious coastal storm swept in from the Pacific, city employees finished dumping around 4,000 cubic yards of sand along the southern end of Ocean Beach. Half of it, or 2,000 cubic yards, washed out to sea. They'll dump another 7,000 yards before the year is out, then dump another 11,000 yards over the following year, at a cost of around $400,000 per year. They do this because the beach is eroding away.

Sooner or later, San Francisco will be forced to choose between preserving the beach and giving up at least some of its road. Current scientific understanding of how beaches erode and replenish themselves makes it clear that reinforcing the ocean's edge to preserve the highway will ruin the beach.

We have one Ocean Beach. The city has hundreds of streets and roads. Every year that we delay making this obvious choice, we waste $400,000.

The beach west of San Francisco has, for more than a century, served as a dumping ground for city detritus -- piles of rock, dirt, and worse. During the 1970s the city extended the Great Highway to the south, linking it to Skyline Boulevard. The roadway was further bolstered during the construction of the city's southwest sewage treatment plant. During the early '90s workers built parking lots reaching out over the oceanside bluffs west of the zoo.

Built bit by bit during the past 100 years, the improvements along San Francisco's ocean shoreline were, according to the most recent scientific understandings of erosion, terribly ill advised.

Not long ago, the ocean began fighting back.

Two years ago the beach's narrowing and resulting erosion became so acute the city declared a state of emergency to obtain permission to dump rocks on the south end of the beach. Now the city dumps sand, which is more expensive, but doesn't exacerbate long-term erosion like the rocks do.

"The real problem at that location is that, over time, the area's been filled, and the bluff that the road and parking lots are located on has been pushed out onto the beach," says Bob Battalia, a San Francisco civil engineer specializing in coastal processes. "The problem is that, whenever we go through a cycle of receded beaches, where we have a lot of wave action, such as El Niños, the ocean tries to move the beach back; it tries to correct itself, and the fill is in the way."

Destructive as the last century of western San Francisco public works construction has been, the harm isn't a result of malfeasance. Scientists and engineers only recently gained an understanding of the way beaches advance and recede through time.

Though they may appear steadfast, beaches are actually as evanescent as unedited words on a computer screen. A healthy beach is buttressed on its seaward edge by sand bars, and by sand dunes on its inland edge. Heavy weather carries beach sand out to the sand bars, the beach becomes narrower, and the stage is set for the beach to be replenished during periods of calmer weather. Over time, the beach creeps back and forth between the dunes and the bars, widening and narrowing in a much slower version of the tides themselves.

Lately, though, the cycles have seemed askew. Since 1993 or so, the beach has been narrowing, and pieces of parking-lot asphalt are now crumbling into the sand over the dunes near Sloat Avenue. "We installed infrastructure within the envelope of fluctuation, and the erosion is really caused by development in that area," Battalia says. "If we hadn't developed that, the beach would move back and forth and recover more quickly."