The bare-bones outline of a report on Sonoma County government's rising pension costs got its first airing Tuesday before the Board of Supervisors.

The report by a committee overseen by supervisors Shirlee Zane and David Rabbitt had few details. Most of those are to come in October when county staff present the full report.

The study is one of two efforts aimed at curbing county retirement spending, which rose more than 250 percent over the last decade. Including additional payments on county pension debt, that 10-year rise is almost 340 percent.

"I think everyone agrees that this board needs to take action to make these benefits sustainable," Zane said in her introduction.

The presentation by county staff included an initial series of findings on county pension costs and other information gathered during the committee's work, which began early this year.

Most of those findings were not new. For example, the board presentation showed the escalating cost of pensions as a percent of the county's payroll. From 2000 to 2010, that rate tripled, to 30 percent of payroll or about $92 million. That means for every dollar the county pays towards salaries, it now pays about 30 cents into its retirement system and toward pension debt to support the current level of benefits.

"The one word that comes to mind is &‘alarming'" board Chairman Efren Carrillo said of those numbers.

Other counties in the state are worse off. Among 19 counties recently ranked highest to lowest on the percentage of payroll going to pensions, Sonoma County ranked 13th — higher than Los Angeles and Tulare, with rates below 20 percent, but well below Fresno, which has a rate over 50 percent, according to a study by the Mendocino County Employees' Retirement Association.

Still, the county's skyrocketing costs are a well-known trend and show no sign leveling off soon, officials acknowledged Tuesday. By 2014, those costs are set to rise another 20 percent, to about $110 million annually.

The full report will offer the county's first comprehensive answer for why that rise has occurred and present some suggestions on how it might be curbed, said Rabbitt, who also serves as a board member of the county's retirement system.

The switch to a higher level of retirement benefits early last decade, the pension fund's $670 million in stock market losses in 2008, and the county borrowing used to pay off those and other losses — now totaling more than $820 million in principal and interest — are some of the largest factors, Rabbitt noted.

"It's important to make decisions that will, if not save money, at least stop the ballooning of expenses and debt," he said.

A labor leader on hand Tuesday said he would wait to see what policy or pension overhaul options the full report puts forward.

"I don't think we heard enough to know where we're going," said Ed Clites, president of the Sonoma County Law Enforcement Association.

Clites and other labor representatives are involved in a parallel process, overseen by the county administrator and personnel offices, looking at options for a lower level of pension benefits for new county hires.

Sonoma County Administrator Veronica Ferguson said she'll take any eventual recommendation from the group as well as any from the board committee's final report into contract negotiations, which are set to begin in the first quarter of next year.