URL: http://sfgate.com/cgi-bin/article.cgi?f=/c/a/2003/01/17/BA58543.DTL

State and federal environmental officials involved in a $100 million deal to buy 16,500 acres from Cargill Inc. offered assurances Thursday that the salt ponds could be restored to wetlands without creating new pollution problems in the San Francisco Bay.

Dealing with the legacy of mercury waste from an old mine in Santa Clara County and the saline waters from commercial salt production will be the two hardest tasks, according to environmental studies released by agencies.

Mercury is toxic to wildlife, as well as to humans who eat tainted fish caught in the bay. Briny waters can injure some aquatic life.

Yet state officials say the ecological value of turning diked ponds into wetlands that feed wildlife, prevent flooding, filter pollutants and provide bayside recreation far outweighs the task of controlling undesirable residues on the land.

Purchasing the Cargill property would be the biggest bonanza in a Bay Area campaign to add 60,000 acres of tidal marshes around the bay, bringing the total to 100,000 acres. At one time, the bay was ringed by 190,000 acres of marshes.

Researchers did not find contaminants in the ponds at concentrations high enough to require removal as hazardous waste, said Al Wright, executive director of the state Wildlife Conservation Board.

Scientists were not surprised to find mercury in the ponds where the mine waste enters the bay through the Guadalupe River. The San Francisco Bay Regional Water Quality Control Board will "manage the circulation of waters there so you minimize any impacts" of the mercury, Wright said.

Lori Johnson, a spokeswoman for Cargill, said the environmental documents released Thursday demonstrated that, "for all those people who thought there might be some secret problem out there, the answer is 'no.' It's all pretty straightforward."

The state Wildlife Conservation Board must approve the Cargill purchase at its Feb. 11 meeting, and the state General Services Office must sign off. The deal would become final in March.

The state is paying $72 million out of funds from Proposition 50, the $3.4 billion bond measure passed in November. The federal government will contribute $8 million, and four private foundations will contribute $20 million.

Officials have refused to release appraisals of the property until the close of escrow, citing only a $243 million independent appraisal approved by the state last year. In negotiations, they say, they must satisfy requests for confidentiality from Cargill and other businesses.

Regulators estimate that more than half of the 16,500 acres are ready to be opened to bay waters. There are about 4,200 acres that may have elevated mercury and about 3,300 acres that may have excessively high salt concentrations.

The largest source of mercury to the bay comes from the long-closed New Almaden Quicksilver Mine. The waste flows 20 miles from the hills down the Guadalupe watershed through San Jose, entering the bay in the area of some of the Cargill salt ponds.

"Of all the substances analyzed, only mercury exhibited ecologically significant concentrations in sediments," said a memo from Steve Moore, an engineer at the regional water board. Nine out of 25 ponds contain mercury at levels that could impair reproduction of fish-eating birds.

The challenge is avoiding the creation of toxic habitat. When inorganic mercury from the mine waste gets into wetlands, it binds with proteins in plants and animals and forms the organic methylmercury, the most toxic form.

E-mail Jane Kay at [email protected].

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