South Bay waters cleaner

South Bay waters cleaner
Study: More Fish, Fewer Contaminants

By Lisa M. Krieger, Mercury News
Friday, September 30, 2005

The waters of the South Bay are growing cleaner and support climbing populations of shellfish and phytoplankton, according to a new report from a leading group of Bay Area biologists and other scientists.

``The ecological conditions in the South Bay seem to be improving'' because of efforts to reduce water pollution and restore habitat, said Christina Swanson, senior scientist with the environmental group the Bay Institute of Novato, which wrote the report.

``If it keeps going on this trajectory, the water in the bay will get clean. We're not there yet,'' Swanson added. ``It takes time.''

The South Bay still contains troublesome levels of mercury, PCBs and other contaminants that are the legacy of old industrial practices, according to Bay Institute researchers.

Of fish caught in the South Bay , 60 percent were contaminated with toxic mercury and 92 percent with PCBs.

The newest and greatest problems are in the upper bay, near the Sacramento-San Joaquin River Delta, where development, dams and agricultural runoff are threatening water quality. Plankton, shellfish and fish populations remain very low in that region, the scientists found.

Overall, the bay is no longer being poisoned by industrial chemicals. Water usage has declined slightly: The average Bay Area resident used an average of 91 gallons of water a day in 2003, down from 95 gallons in 2000 -- but far more than the 79 gallons used at the end of the 1987-1992 drought.

But the bay is being starved of fresh clean water from its rivers, needed to support plant and animals. The report, called ``The 2005 San Francisco Bay Index,'' uses three dozen science-based indicators to grade the condition of the bay. A similar report was issued in 2003.

These indicators were combined into eight categories including environment, fish, wildlife, and value to the people of the San Francisco Bay region.

The specific South Bay findings include:

• Acquisition of tens of thousands of acres of salt ponds, agricultural lands and former military bases means that the future bay shoreline habitat could be 50 percent larger than its current size. Restoration of these habitats is a key element in protecting the bay.

• Overall, fewer contaminants reached dangerous levels. The industrial chemical PCB declined in concentration, but nearly 90 percent of all water samples from the bay continue to have excessive levels of this contaminant.

• Levels of phytoplankton, the microscopic floating plants that are the base of the bay's food web, are increasing. Suisun Bay has phytoplankton levels that are 77 percent lower than the South Bay because of the invasion of a non-native clam.

• Overall levels of shrimp in the bay doubled in the past decade. There has been a threefold increase in the South Bay .

• Bottom-feeding fish have increased 29 percent in the South Bay from 2003 levels but are substantially lower than populations in the early 1980s. Open-water species have decreased in all regions of the bay.

``This is really good news," said Palo Alto City Councilwoman Dena Mossar.

Contact Lisa M. Krieger at lkrieger@mercurynews.com or (408) 920-5565.