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Salt Pond Restoration Prognosis
A forthcoming study commissioned by Save the Bay suggests that restoring wetlands on some of the South Bay’s salt ponds may cost a pretty penny. Though the region has long sought the ponds as rare restoration turf in a built-up bayshoreline, and though Cargill has offered to sell up to 19,000 acres of its South Bay ponds to federal and state agencies interested in boosting the region’s long lost supply of tidal marsh, the endeavor has its trade offs and expenses, say authors of the study.
"It’s very doable, but we have to acknowledge upfront what the full costs are and appropriately fund them, or we’ll face extreme consequences, like failing flood control levees," says Stuart Siegel, who is co-authoring the study with Philip Bachand of Wetlands and Water Resources (WWR).
The two researchers expect to release their South Bay salt pond restoration feasibility analysis in early 2002. This report, funded in conjunction with the Coastal Conservancy and WWR, describes the biological, chemical, physical and environmental characteristics of the salt ponds and the issues related to their restoration as tidal marsh and managed open water.
According to Siegel, the report identified four key challenges to restoration, two of which were obvious, and two unexpected. One obvious one is the bittern, the hypersaline byproduct of salt production, and who will end up disposing of it. Siegel and Bachand estimate that Cargill is storing over 15 million tons of liquid and solid bittern in its facilities. Under current negotiations, Cargill is expected to retain all the bittern. But given the combined long time frame for restoration, and the apparent decreasing economic feasibility of Bay Area solar salt production, Siegel says any agencies taking over the ponds should investigate their bittern disposal options.
The second obvious challenge is that restoring the salt ponds to tidal marsh may displace some birds. Several species have prospered from the managed salt ponds, and many are now protected by state and federal endangered species laws. Any comprehensive restoration program will have to preserve roughly a third to half the salt ponds as managed open water habitats to continue supporting these important wildlife resources.
"One reason the costs of this restoration effort will be so high is the region’s desire to maintain some managed open water in perpetuity," says Siegel.
Two other less obvious factors will make things costly, the sediment deficit and levee maintenance. Extensive groundwater withdrawal and other processes have caused subsidence that equates to a sediment deficit of over 100 million cubic yards to restore salt ponds to marsh plain elevations. Under natural sedimentation, it would take over 100 years to restore the salt ponds without scouring nearby mudflats. Though dredged material could accelerate restoration, its use will add to the costs.
In addition, the forthcoming feasibility study concludes that salt pond restoration will entail substantial interim and permanent management costs on top of purchase costs. Flood control levee maintenance and water management will require approximately $250 – 500 per acre annually. During restoration planning, total annual costs would be highest, between $5 and 10 million for a 19,000-acre purchase and $3 to 6 million for a 13,000-acre purchase. As tidal marsh restoration proceeds, these costs would decline to a fixed minimum corresponding to acreage of ponds retained as managed open water (plus adjustments for inflation).
The new feasibility study will be available in early 2002.
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