San Pablo Bay 'in trouble'

2005 'Bay Index' cites fewer fish, more pollution in San Francisco Bay's northern reaches

October 19, 2005

By COREY YOUNG
ARGUS-COURIER STAFF

San Pablo Bay, where the Petaluma River empties into the ocean, is one of the least-healthy parts of the San Francisco Bay estuary.

That's according to a new report by the Novato-based Bay Institute, a non-profit group focused on protection and restoration of the bay environment.

While the overall picture of San Francisco Bay's health is one of "modest improvement," the northernmost portions of the bay are "in serious trouble," the institute's 2005 Bay Index found.

"The further upstream you go in this estuary, the worse the conditions," said Christina Swanson, Ph.D., the organization's senior scientist.

What is setting off alarm bells about San Pablo Bay, and Suisun Bay further north, are critically low populations of native fish and other species, poor water quality and a loss of native habitat like wetlands, Swanson said.

"We are seeing really worrisome, low levels of native fish in San Pablo Bay," she said.

Populations of open-water fish species in San Pablo have declined 73 percent since 1991 and 84 percent since the mid-'80s, the report found.

Levels of bottom-dwelling fish in San Pablo are 70 percent lower than the early '80s, the report also said.

But at the other end of the "food web," phytoplankton and zooplankton -- microscopic floating plants and animals -- have been stable in the area, she said.

"The lower level of the food web appears to be stable and possibly improving," Swanson said.

However, "fish are often considered to be the ultimate indicator," she said. "It's on that basis that we say San Pablo Bay is threatened."

Scientists are concerned that the declining fish levels are "an indicator of future ecological collapse" due to poor water management in the Sacramento River Delta upstream, toxic contamination in the bay and an influx of non-native fish species, Swanson said.

They believe manmade changes in the amount of freshwater flowing into the bay has changed the habitat for native fish for the worse. A lot of the typically high springtime flows in rivers have been reduced, she said.

"That represents a very fundamental change in environmental conditions in this estuary," Swanson said. "It's not particularly surprising that fish aren't doing that well -- what happens upstream matters to San Pablo Bay."

Complicating the situation for bay life are polluted waters caused by runoff of toxics from human uses and loss of tidal wetlands that are a necessary habitat for fish and other creatures, the report said.

"It's important habitat for the animals that live in the open water" as well as those living closer to shore, because it provides "services" like pollution filtering and spawning and nesting grounds, Swanson said.

The Bay Institute is working in the North Bay and elsewhere to restore such habitat, and public participation is a big part of addressing the problems found in the 2005 index, said Executive Director Grant Davis.

Planned restoration of wetlands at areas along the Petaluma River like Shollenberger Park, the city's new sewer plant and open space like the Dickson Ranch is needed to improve the bay's health, and public support is needed to continue the efforts, Davis said.

"This marsh complex is the largest intact tidal wetland in the San Francisco Bay," Davis said. "It's remarkable that it has remained relatively unspoiled to this date."

The Bay Institute report said ways for the public to help improve the bay's health include joining habitat-restoration efforts, using safe chemicals that won't add to pollution and using less water around the home.

The full Bay Index report can be viewed online at www.bay.org.

(Contact Corey Young at cyoung@arguscourier.com)