A Grassroots Effort Bay Bridge Construction Project Incorporates Eelgrass Preservation

It will take steelworkers, pile-driver operators and hundreds of other construction workers in hard hats to build the $2.6 billion eastern span of the Bay Bridge, lifting the concrete pieces into place and creating the signature single-tower suspension span.

But it will also take a group of underwater gardeners working on the bay floor in an effort to transplant and preserve an underwater plant -- eelgrass - - that many would simply dismiss as seaweed.

Eelgrass -- zostera marina -- is a thin-rooted plant that grows on the mucky bottom of the bay in shallow waters, typically keeping its flat, deep- green leaves, which can grow up to 3 feet long, beneath the surface. Beds of eelgrass provide valuable habitat for fish and fowl -- spawning grounds for herring, food for black brant geese, and shelter for shiner perch and other fish.

"It's an important resource for the bay," said Jeff Jensen, biological mitigation manager for the state Department of Transportation.

Which is why Caltrans is spending $1.2 million of its eastern span construction budget to study how best to transplant eelgrass.

"What we've been finding out," said Keith Merkel, chief ecologist for Merkel & Associates, a San Diego environmental firm hired by Caltrans, "is how little we know about eelgrass in San Francisco Bay."

The experimental eelgrass project is part of an approximately $20 million package of environmental mitigation projects that aim to help make up for the deleterious effects that construction of the new span will have on the bay and its flora and fauna.

Other environmental efforts include restoration of Skaggs Island; a program to encourage spawning of salmon and steelhead that uses special air-bubble devices to protect fish from the acoustic waves generated by pile driving; monitoring of the bay for marine mammals during construction; treatment of storm-water runoff from the Bay Bridge Toll Plaza and Interstate 80, and restoration of eelgrass and sand flats at the new Eastshore State Park.

Eelgrass is believed to have once thrived in the bay, but only 450 acres remain. One of the largest beds sits off Emeryville, where construction crews will have to rip up 3.2 acres of eelgrass to create a barge-access channel.

Caltrans hopes to replant the channel with eelgrass once the new bridge opens in 2006. But while eelgrass transplants have worked elsewhere, none has ever succeeded in San Francisco Bay, where the murky waters, wind and waves make for a less than hospitable environment.

Read More!