AC Transit is facing a projected $57 million deficit after cuts in the state budget and significant reductions in sales and property tax receipts, and will cut at least 15 percent of its bus service, transit officials said.

Already, a bus line that goes to California Memorial Stadium on Cal football game days has been axed, and two lines that service the Oakland Zoo and bring about 8,000 schoolchildren there each year could be eliminated.

"We are mainly concerned about the kids," said zoo spokeswoman Nancy Filippi. "There are 7,000 to 8,000 kids who come here to take the educational classes. Now those children won't be able to get that extended science education."

What's more, between 40 and 50 zoo employees take the 56 and 98 lines to work. One of those lines, the 98, also provides service to neighborhoods in and around Golf Links Road, zoo officials said.

When Cal football kicks off Saturday, it will be the first time in 30 years that AC Transit has not supplemented the 51 line to accommodate the thousands of riders traveling from Rockridge BART, the Berkeley Amtrak station and downtown Berkeley to the stadium. The cost of providing the additional service has been more than $200,000 per season, transit officials said.

Without a full subsidy from UC Berkeley, AC Transit had to discontinue the added gameday service as part of cost-cutting and service reduction measures. UC Berkeley has hired a private bus operator to provide

"I don't think fans will notice the difference," Benenson said. "We will still have bus service that will take them straight to Memorial Stadium, essentially along the same routes."

The cost of the shuttle will be $5 round trip or $3 one way. More information is available at www.calbearsbus.com.

In an effort to streamline the service amid the cuts, AC Transit will hold 10 public forums around the East Bay to unveil its adjustment plan. But this round of cuts may not be the last.

Over the next two years, the transit district is expected to suffer significant declines in its main revenue sources.

There has been a steady decline in revenue from sales taxes, but Gov. Arnold Schwarzenegger's decision to cut state transit assistance funding for the next five years, redirecting more than $100 million that could be used to keep bus services intact, has made things worse, transit officials said.

Already the district has laid off employees, frozen positions, increased fares and reduced departmental spending by 15 percent.

"Despite our fiscal dilemma, the idea here is to not overly inconvenience our riders, to become even more efficient without dramatically disrupting our service," said AC Transit General Manager Rick Fernandez. "We have worked in earnest to do that."