Any overhaul of the Sonoma County pension system faces mounting challenges, including opposition from unions and inaction in Sacramento.

A group of state legislators is expected to roll out proposed reforms for local and state systems this month, but they are expected to encounter resistance from organized labor.

Under the package of changes endorsed by the Board of Supervisors last week, final-year bonuses for department heads would be eliminated along with the county-paid contributions to deferred compensation accounts that benefit managers and elected officials most, adding up to 6 percent to salaries.

The perks have been under constant fire from union leaders.

"If you're already paid a really generous salary, having all these extras that add 15 percent to final salary seems like it could be abusive," said Lathe Gill, area director for Local 1021 of the Service Employees International Union, the county's largest labor group.

The average boost over salary for county employees with final compensation of at least $100,000 is 14.5 percent.

For their part, representatives for Sonoma County government managers said they have little choice but to accept the pension overhaul proposal, which also eliminates, for pension purposes, cashouts of accrued vacation and other leave, and would set lower benefit tiers for future workers.

"Considering the county's (fiscal) situation, it's inevitable that changes have to be made," said Lou Maricle, chairman of the Sonoma County Administrative Management Council, the largest management group.

The SEIU, which represents about half the county's 3,400 workers, has remained guarded about larger changes to the pension system, including the lower benefit tiers for future hires.

Such systems tend to pit generations of workers against each other, Gill said. Other changes may be in order, he added, suggesting the union would look at the proposed elimination of leave cashouts from pension consideration and reduction in premium pay categories.

"We recognize that our members do have some spiking opportunities. We think those things can be perceived as abusive and that there are acceptable reforms," he said.

The proposed move from a single-year total to a three-year average for final compensation when computing pension amounts is one the union might agree to, Gill suggested.

A representative of the county's largest group of public safety workers suggested his members could agree to a lower tier of benefits for future workers, but would oppose a rollback in premium pay and shift differentials. Such incentives are needed to fill off-hour duties and improve training, said Ed Clites, president of the Sonoma County Law Enforcement Association.

"We fought long and hard to get those things," he said. "I don't see those going away. If they did, we would oppose it."