Sonoma County?s Board of Supervisors moved Tuesday to shift a greater share of medical premiums onto 2,700 public employees after five months of failed talks with the union representing the workers.

The unilateral action converts the county?s share of health care premiums for employees to a $500 monthly contribution, eliminating the current payment that is equal to 85 percent of the employee?s health plan choice.

Officials with the union representing those workers, the Service Employees International Union, had countered with a proposal calling for employees to pay set amounts for medical premiums based on whether they insure dependents.

But the supervisors were unanimous Tuesday in contending that the county plan makes more headway in addressing rising health care costs.

County officials said there is a $14 million annual gap in covering ongoing costs of worker and retiree medical benefits, and if left to accumulate it could lead the county to eliminate the benefit.

?The fact of the matter is the dollars aren?t there to do what we?ve done in the past,? said Supervisor Tim Smith.

The supervisors acknowledged the rancorous negotiations with SEIU, but sided with county administrators on the plan that is similar to those imposed on the county?s 2,400 retirees and 650 nonunion workers.

?Sometimes we have to make very difficult decisions and this was one,? said Supervisor Mike Kerns.

The change in medical premiums for current employees takes effect in June. The county also approved a $600 monthly bonus that can go toward salary or health premiums.

Similar changes in medical premiums for retirees also take effect in June. For retirees, the county currently pays 85 percent of the county?s lowest-cost health plan.

Union officials criticized the board taking its final vote on election day, when many union supporters are busy working for candidates.

SEIU and other unions backed candidates for several supervisorial seats in hopes a new board would reconsider the current board?s decision.

County administrators and SEIU are expected to begin a new round of contract talks in February.

You can reach Staff Writer Michael Coit at 521-5470 or