Study: Sediment, Tidal Marshes Are Key To Protecting Bay Area From Rising Sea Levels
SAN FRANCISCO (KPIX 5) -- Scientists warn that sea level rise is a problem that cannot be ignored. But a new study says the secret to protecting the Bay Area may rest with something that is currently being thrown away.
San Francisco will spend billions of dollars over the next 30 years to build up a few miles of seawall along the Embarcadero to protect it from rising seas. But the rest of the Bay Area has something that may work even better: tidal marshes.
"We are so lucky in the Bay Area that we have these tidal marshes. We have this option if we choose to take it," said Dr. Letitia Grenier, Senior Scientist with the San Francisco Estuary Institute. She said shoreline marshes are a natural form of seawall that grow higher as the water level rises. Each high tide deposits a new layer of sediment to the marsh. The more mud washed into the marshes, the faster and higher they will grow.
"These wetlands can actually grow vertically to keep up with the water as long as they have enough mud to do that," she said, "and the plants will grow right up through all that mud."
The Institute released a study Tuesday entitled "Sediment for Survival" that says the amount of mud needed to protect the Bay Area would fill 48 million dump trucks, enough to circle the Equator tens time over.
"That's what the report was about," said Dr. Grenier. "We said to ourselves, how much mud do we really need and where can it come from? And the great news is, we actually have enough mud."
They recommend that sediment already being dredged from the Bay everyday be used for this purpose. Right now, the U.S. Army Corps of Engineers pays to have the mud hauled far away and dumped. But David Lewis, Executive Director of the conservation group Save the Bay, said the challenge will be to convince the government to pay a little more to use the mud as a valuable resource instead of just throwing it away.
"If the Army Corps of Engineers would change their policies, we could promote this reuse and have it be affordable and really protect the Bay Area and the Bay from sea level rise," he said.
The strategy is already being used in Marin County. Dredge material is being used to restore a wetland marsh on the former site of the old Hamilton Airfield. The clock is ticking. Sea level rise is expected to accelerate quickly and Dr. Grenier said spending the next 10 to 15 years growing the marshes could prevent billions of dollars of damage in the decades to follow.
