The agency that operates SamTrans service said Monday it will lay off 45 bus drivers and administrative workers next month, the latest blow to the transit operator that will soon offer riders fewer routes and higher fares.

San Mateo County Transit District officials said the agency's financial future was too bleak to avoid severing ties with staff members come Dec. 20, when they will cut several routes from the SamTrans schedule.

The district will part ways with 37 bus operators and eight members of its administrative staff, which split time working on SamTrans's sister agency, Caltrain, at their joint headquarters in San Carlos. The total employee head count at SamTrans will drop 6 percent from 717 to 672.

The SamTrans governing board voted in September to slice 7.5 percent of the system's operating schedule, which ultimately led to the layoffs, said spokeswoman Christine Dunn.

Despite the service and staff cuts, however, the district has knocked only $10 million off the $30 million deficit they faced when the current fiscal year began in July, Dunn said. The district will also raise base fares by 25 cents in February.

Dunn said the transit operator may dismiss more staff members next year. SamTrans has lost its state funding, seen its ridership and sales tax revenues fall and faces a 10-year funding shortfall of $163 million.

Those employees who kept their jobs won't have much to celebrate, either.

Administrative employees will not receive pay hikes of any kind this fiscal year, Dunn said. After taking four furlough days last year, the remaining staff will swallow six more furlough days this year, saving the district an anticipated $150,000, she said.

Local labor officials said they met with the affected employees and provided presentations on county services available to them. Dunn said the district would provide severance pay based on employees' contracts.

A spokesman for the local Amalgamated Transit Union, which represents the bus drivers, could not be reached for comment Monday.

Mike Rosenberg covers San Mateo, Burlingame, Belmont and transportation issues. Reach him at 650-348-4324.