Sonoma County has reached a tentative labor agreement with sheriff's deputies that includes reduced pension costs for taxpayers and increased county contributions toward employee medical expenses.

The deal with the roughly 217-member Sonoma County Deputy Sheriff's Association puts the county on track to trim more than $160 million off its pension costs over the next 10 years, officials said.

The savings estimate, including concessions already achieved in labor contracts reached this year and two other tentative deals up for approval, would beat a target established by the Board of Supervisors two years ago, when officials said the county needed to trim $150 million in pension-eligible pay over the next decade to make the county's retirement system sustainable.

"We have to give our employees credit for stepping up to achieve that," said Supervisor David Rabbitt, board chairman.

The deputies' deal goes to the Board of Supervisors on Tuesday for ratification along with proposed contracts for two smaller groups, representing sworn sheriff's office management and heavy equipment operators.

The deputies group has agreed to the same baseline cut of 2.25 percent off overall compensation that the county settled on earlier this year in contracts with its main rank-and-file labor groups.

Other labor deals recently with county prosecutors and public defenders have resulted in slightly greater overall cuts to compensation. The largest reductions, of 5 to 8 percent, were taken by the highest paid employees, including administrative managers, department heads and county supervisors.

Including the three deals up for approval today, the county has now settled with 10 of its 11 bargaining units, representing more than 3,300 employees.

All of the deals are aimed at securing permanent reductions in pension costs, which have soared in the past decade, consuming an ever greater share of taxpayer money and impacting a range of public services.

A decade ago, pensions took up only about 8 percent of county salary and benefit costs. Now, taxpayer contributions to county pensions and payments on pension bond debt account for about 19 percent, or $98.3 million, of the county's current $530 million payroll.

The gross annual savings from labor negotiations to date — $16.7 million — represents about 3 percent of total payroll.

The combined net annual savings from the labor deals is less than $12 million, including about $1.2 million from the agreement with deputies. The difference between the net and gross savings figures reflects the additional $5 million the county has agreed to contribute to date toward rising employee medical expenses.

The lump sum and monthly payments to health reimbursement accounts, when combined with insurance coverage, will increase county medical spending on employees by about 20 percent.

Rabbitt said he was less concerned about that increase because the county has had more success keeping a lid on its health care costs than other payroll expenses in recent years.

Generally, local governments have had more flexibility under California law tinkering with medical benefits than pensions, which enjoy strong legal protection.

"It all concerns us," Rabbitt said of the medical cost increase, "but in the big picture, the movements we've made on pensions will put us on a more sustainable financial footing."

The most significant pension savings under the new round of county labor contracts come from the state-mandated lower benefit formulas established for new hires.

Current employees would be required to pay a greater share of their pension premiums. For deputies, under the proposed deal, that meant losing a county paid "pension pickup" of 2.6 percent, equivalent to about 20 percent of their yearly premium.

The perk had been highest for the Board of Supervisors, which enjoyed a 50 percent pickup before it was eliminated this year.

The contracts have also curtailed moves that can spike pay and an employee's pension through cashouts of accrued leave and other moves. The average boost has been highest for county deputies and other public safety workers, according to a Press Democrat analysis last year of thousands of county pension records.

For career county deputies and other public safety workers who retired in 2011, the average annual pension was $94,000, the analysis found, more than double the average pension for retirees from a decade before.

Deputies and sheriff's sergeants were among the only county employees who received cost-of-living adjustments and equity increases to their wages since the recession. Combined, the boost totaled about 6 percent.

But county officials did not seek greater cuts out of the group because of past pay increases. When their new agreement expires in December 2015, deputies will have received the same 3 percent bump in wages guaranteed in contracts with the other represented employee groups.

The bottom line was savings going forward, not what had been negotiated in past contracts, Rabbitt said. "The county's goal was to be consistent with all groups across the board."

Both the Deputy Sheriff's Association and the smaller group of sheriff's office management, including 11 members from the ranks of lieutenant up to assistant sheriff, have signed off on the tentative deals. The group of managers would take an overall cut of 3.13 percent.

John Noble, a labor representative for the two groups, declined to discuss the deals or the employees' ratification votes ahead of the Board of Supervisors decision Tuesday. "After the board is done, then we may have some additional comments," he said.

The other tentative agreement with the International Union of Operating and Stationary Engineers, Local 39, representing more 100 than employees, also proposes an overall compensation cut of 2.25 percent.

The lone group still at the bargaining table is Engineers and Scientists of California Local 20 IFPTE, which represents about 235 county workers.

You can reach Staff Writer Brett Wilkison at 521-5295 or brett.wilkison@pressdemocrat.com.