Talk of restoring the Bay Area's tens of thousands of acres of former salt ponds to tidal marshes tends to conjure a rather irresistible image: A bright yellow earthmover tears a massive rift in a century-old levee and returns the tides to coastal areas from which they've long been estranged. Soon native vegetation appears, then birds, and eventually the once-desolate flats become a thriving tidal wetland. The recovery is natural, wild, and absolutely inevitable. Except that it's not.
The reality is that saltworks along the perimeter of the San Francisco Bay — some of which date back to Gold Rush days — have permanently altered the landscape and its ecology. Even if all of the hundreds of levees that divide the once vast tidelands into salt ponds were to be breached, the bay's wetlands would not automatically revert to their formerly productive state.
That's why an experiment being developed by Memphis-based hunting and conservation group Ducks Unlimited at Hayward's Eden Landing Ecological Reserve is so important. It will tell biologists precisely which salinities, flow rates, and water depths are ideal for different target species, from invertebrates up to migratory birds. With this information, they'll be able to dial in precise habitats at the turn of a wheel, and optimize former salt ponds for different uses throughout the year. If we simply let nature have its way, many species could be left out of the loop.
John Krause, a wildlife biologist with the California Department of Fish and Game, manages Eden Landing's more than five thousand acres. Standing on a levee overlooking a desiccated former salt pond, he explained how, with Fish and Game's help, later this summer Ducks Unlimited will begin constructing a first-of-its-kind, full-scale experiment that will inform future wetland restorations throughout the bay and even around the world. "This is the bird lab," he proclaimed.
Instead of being restored to tidal influence, two large ponds totaling 230 acres will be equipped with sophisticated water-control structures and an additional network of interior levees, dividing them into a series of smaller cells. They'll then be reconnected to nearby Mt. Eden Creek, a natural waterway under tidal influence that reaches out to the open bay. Over time, water will be carefully pumped from one cell to the next, increasing in salinity along the way due to evaporation, and finally sent to a mixing pond before being returned to the creek. Throughout the process, biologists will tinker with different variables and monitor how they impact the mix of species that feed and nest in each cell. The experiment should begin in early 2014 and run for up to ten years, said Krause, after which point the ponds will be configured for maximum productivity indefinitely.
One of the biggest beneficiaries of the work will be the Western snowy plover, a sensitive, threatened shorebird whose plumage is camouflaged against the whitish soil of former salt ponds. "Dry pond bottom is a substrate that mimics beaches and other things that they historically nest on," Krause said. "And since there's not much of this, they use the former ponds."
This artificial, accidental habitat has become central to the species' survival in the Bay Area. But by simply breaching levees wholesale and allowing tides to flow freely, much of it could be lost. Managed ponds, where tidal flows are restricted, will protect the plovers by including manmade islands for nesting and guaranteeing a nearby food source in the form of brine fly larvae. Biologists will learn to create optimal high-salinity conditions for the flies through Ducks Unlimited's experiment.
The Eden Landing restoration will also improve conditions for waterfowl, including the mallards, scaups, and pintails that already frequent the area, but Ducks Unlimited's interest in the site extends well beyond enhancing local duck hunting, said Steve Carroll, a regional engineer with the private nonprofit. "Our mission is to fulfill the needs of North American waterfowl," he said. "We're just trying to keep the ecosystem healthy." Duck hunting has a long history at the Hayward salt flats, with previous landowner Cargill leasing some of its ponds to local clubs. Fish and Game, which acquired the land in 2003, continues the tradition by organizing up to twelve small-scale public hunting days each year at Eden Landing.
Laura Wainer, a senior scientist with environmental nonprofit Save the Bay, is excited about the experiment's prospects for all species. "There's an amazing opportunity to learn from the managed ponds," she said. "It gives a great opportunity to learn about what birds and what fish and what invertebrates can live in these areas, as we continue to restore wetlands around the bay."
Ultimately, only a small portion of Eden Landing's total area will become managed ponds. Within the South Bay Salt Pond Restoration Project — a multi-agency effort to restore 15,000 acres of former salt flats in the area — the target is 90 percent tidal wetlands and 10 percent managed ponds. Elsewhere around the bay, where Save the Bay hopes to see 50,000 acres of new wetlands restored by the end of the century, the ratio could be similar. With the help of findings from the Eden Landing experiment, managed ponds will do some heavy ecological lifting.
The Hayward reserve is already on its way toward becoming a biological hotspot. Last year, Ducks Unlimited led a project to breach multiple perimeter levees and welcome the tides to certain areas for the first time in more than a century. The pools they've inundated are slowly returning to life. In addition, Save the Bay has been working with volunteers at the site since 2006 to plant native vegetation and remove invasive species on levee slopes and tops. These manmade structures above the tidal zone are sometimes overlooked as habitat, Wainer said, but they can provide critical protection for shorebirds during high-water events.
Even with the restoration in its earliest stages, Eden Landing's ponds are visited by a variety of birds, including egrets, herons, terns, curlews, cormorants, pelicans, avocets, and the endangered California clapper rail. The endangered salt marsh harvest mouse has also been spotted.
Construction of the salt pond experiment is funded by an $8 million grant to Ducks Unlimited through the California Wildlife Conservation Board, a division of Fish and Game. The money will also go toward a series of public-access improvements that should be complete by the end of next year, including installation of the only boat ramp in this portion of the bay; extension of the Bay Trail to the terminus of one perimeter levee; and construction of a boardwalk over the otherworldly remains of a former saltworks operation, where preserved wooden pilings still jut from the barren earth in neat rows.
That's just another example of how restoring former salt ponds isn't always as clear-cut as it seems. Where humans once distorted the landscape, we now must take care in repairing it. "Based on the conditions that already exist," Wainer said, "we're trying to create the best systems that we can."