Built in 1925, the Plunge, is listed on the National Historic Register for its distinguished elaborate ornamentation fronted by four columns. For decades,

this indoor pool in Point Richmond has been a favorite recreation spot for East Bay families.

But safety at the city-run Plunge has been debated since the 1989 Loma Prieta earthquake. Signs already warn occupants to swim at their own risk because of possible structure damage.

The decision to close the 76-year-old structure came suddenly yesterday, when the city's director of public works was informed of the bulging wall on the west side of the building.

"He was concerned that it might be something new, not something that's been there for a long time," said Councilman Tom Butt, who has been a strong advocate of rehabilitating the building.

Butt said the public works director will call a structural engineer to determine if the weathered structure is safe.

City officials have been arguing about the Plunge, known officially as the Richmond Municipal Natatorium, for years.

Building inspectors in 1997 recommended that the pool be closed. But the City Council voted to keep it open until an election to decide its fate was complete.

Voters in November 1997 overwhelmingly turned down Measure H, a $24 million bond issue that would have paid for seismic upgrades to the Plunge, City Hall and the Hall of Justice.

Butt said repairs at the Plunge could cost between $5 million and $8 million. He said the city already has $1.5 million earmarked for the Plunge, and a private foundation has raised $250,000.

A closed City Council meeting is scheduled for this morning to discuss the potential legal problems with the 20-by-50-yard pool.

Chunks of stone are falling off some parts of the building, and reinforcing rods stick out in other places.

"It's a treasure," Butt said. "There's probably tens of thousands of people who learned to swim there."

Former Councilwoman Donna Powers said she was one of two who years ago voted against keeping the building open, even though she lived in the neighborhood and her children learned to swim there.

"I lived in Point Richmond when I voted to close it and I caught holy hell, " she said. "To close the Plunge is really going to stir up a hornet's nest."

Powers made note of the fact that there is another city election in November, with four members of the current City Council running for mayor.

The Richmond city Web site still had summer pool hours at the Plunge listed last night, but officials said swimmers would be redirected to the pool at Kennedy High School.