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cost, limited effectiveness, questionable feasibility, and probable significant adverse economic and ecological impacts of such a project, it does not seem prudent to seriously further consider such a proposal,” the report concluded.
But that was before the UN’s Intergovernmental Panel on Climate Change warned that a three-foot rise in sea levels is almost certain by 2100; before Sandy ravaged the East Coast and a “Pineapple Express” storm dumped an unprecedented 13 feet of snow in the Sierras in December 2010; and before a tsunami devastated the coast of Japan and sent a one-foot surge into San Francisco Bay. In light of our growing understanding of the climate picture, some observers are saying it’s time to take another look at the Golden Gate Barrage. (The project has also been nicknamed “Goldilocks,” since a major system of locks would be needed to accommodate ship traffic.)
In the design considered by BCDC, the barrage would be about two miles long and would rise 500 feet above the bed of the Bay. To maintain the character of the Bay-Delta system as a tidal estuary with a mix of salt and fresh water, and to deal with flood conditions during winter storms, the barrage would need to include pumps to bring a controlled amount of water into the Bay at high tide and send it back out into the ocean at low tide. In the early years, before ocean levels rise too high to permit a natural flow through the barrage, there might also be the opportunity to generate some tidal power using hydro turbines built into the dam. The design would also have to include a wildlife gate to give safe passage to fish, sea lions, and other critters.
The engineering challenges would be mind-boggling. But the attraction of the Golden Gate Barrage idea is that it would offer blanket protection to the entire Bay and Delta, saving numerous local governments and property owners from having to build levees. (The levee solution would almost certainly lead to massive economic injustice, as the Bay Area’s wealthiest communities and property owners rushed to build their levees first, redirecting the rising waters toward less-well-off communities.)
There are, of course, many potential flaws in the Barrage plan, and the political, environmental, and commercial objections would be numerous. For one thing, building the Barrage would create a single point of failure: if it broke, the whole Bay would be flooded. The BCDC also pointed out in its 2007 study that artificially restricting the flow of water through the Golden Gate would likely affect sedimentation patterns, salinity, animal migration, and the health of wetlands along the Bay. Then there’s the stupendous cost. The largest similar structure built to date, the Three Gorges Dam in China, cost $15 billion, and it isn’t nearly as tall as the Golden Gate Barrage would have to be.
But it’s an option we can’t afford to rule out, at least in the eyes of Ezra Rapport, executive director at the Association of Bay Area Governments. “Ultimately, this might be the solution, but I do not think it’s one we are quite ready to adopt today,” Rapport said during a March 2013 panel discussion at the Commonwealth Club in San Francisco. “We don’t have the engineering studies ready.”
If a single huge dam isn’t to your taste, there’s another intriguing idea on the table, called Folding Waters. Proposed by the San Francisco architecture firm Kuth Ranieri as part of a 2008 competition sponsored by BCDC, it calls for the installation of 15 permeable levees to protect the Bay’s most sensitive inlets. The levee tops would sit at water level, but would have wings that pivot upward with the rising tide, creating long waterfalls, similar to the edge of an infinity pool. The water would cascade into a shallow gutter, where it would be pumped back out into the Bay. More pumps built into the walls would create simulated tides to nourish the protected side of the levees.
No one knows how much Folding Waters, or the Golden Gate Barrage, would ultimately cost. Protecting the Bay with traditional levees, or new wetlands and tidal marshes, or a controlled flooding scheme, might turn out to be cheaper and more environmentally sound. The point is that it’s time to start doing the engineering studies. We need to figure out the likely costs, balance those against the costs of doing nothing (which are also stupendous), and then bring local, state, and federal authorities together to invent financing mechanisms.
One way or another, Silicon Valley corporations are going to get hit with part of the cost, so they might as well grab a seat at the table now. Maybe they can even divert a bit of their fabled brainpower to generating new engineering responses to sea level rise—preferably ideas that spread the costs evenly, promote equitable development, and preserve the Bay Area’s natural beauty.
The only other option is what’s called “managed retreat”—that is, admitting that the rising waters are unstoppable, ceasing all waterfront development, and gradually moving people and infrastructure to higher ground. But at the moment there isn’t anywhere for companies as big as Google, Oracle, or Facebook to go. And I just can’t see municipalities voluntarily abandoning big chunks of their territory—also known as their tax base—to the sea.
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