Sonoma County supervisors Tuesday morning honored one of their own, Valerie Brown, who is set to retire at the end of this year after 10 years on the county board.

Chairwoman Shirlee Zane called Brown, the county's only current two-term supervisor, a "historian, mentor and role model" for the board.

"I believe you have made a huge difference not just locally but nationally," Zane said.

A former state assemblywoman and Sonoma mayor, Brown, 67, is one of the few county leaders with state and national experience. She was president of the National Association of Counties in 2009-10 and serves on a national public health advisory group for a White House council overseeing health promotion and disease prevention.

Supervisor David Rabbitt called that range of experience vital to the county during Brown's tenure. "You have left an indelible mark on this county," he said.

Brown was appointed by Governor Gray Davis to the Board of Supervisors in 2002 to fill a vacancy in the 1st District seat, representing Sonoma, Sonoma Valley and eastern Santa Rosa. She prevailed in two elections, in 2004 and 2008, before deciding not to seek re-election.

Supervisor-elect Susan Gorin, who topped fellow Santa Rosa City councilman John Sawyer in last month's election, is set to take over Brown's seat at the start of next year.

As a supervisor, Brown has gained recognition as a leader on health care, energy efficiency, climate protection and social welfare programs.

County Counsel Bruce Goldstein said she was the board member he and others in his office often relied on dealing with complex government issues. "You're the one that counsel seeks counsel from," Goldstein said. "That's going to be sorely missed."

Supervisor Mike McGuire called her the "rock of this board" and Supervisor Efren Carrillo said she had set the bar high for current and future board members.

A self-described moderate, Brown closed out the 20-minute recognition by urging her colleagues to follow a similar path.

"If you're a left-wing Democrat or a right-wing Republican, nobody needs to sit down and talk with you because they already know who you are," she said. "You have to be in the middle."

She ended by thanking fellow supervisors, county staff and others she said had guided and shaped her county career.

"Goodbyes are really hard and it seems like I've been experiencing them for two months now," she said. "Thank you for making my time here a blessing. I'm so grateful to all of you."