Boesch announced his resignation after a closed session with the Board of Supervisors. He said it was clear he and the board had "different philosophies."
Boesch's resignation is effective Dec. 31, but his last day will be Nov. 15. From that time until the end of the year he will be providing assistance to an interim county manager yet to be named. The county will be conducting a nationwide search for a new county manager.
Boesch, a former Menlo Park city manager and assistant county manager, was named county manager in 2008 after the retirement of John Maltbie. Maltbie served as county manager for 19 years.
When Boesch came on board, the county faced a structural budget deficit of more than $100 million. Currently, the county has a balanced budget for fiscal year 2011-2012 with a roughly $30 million reduction in spending and a reduced reliance on reserves, officials said.
"I have a real passion for working on problems that on the surface seem intractable," Boesch said in a statement. "What I have learned is that almost any problem is solvable if you bring together the people involved and demonstrate a genuine commitment to working in partnership toward a solution."
Board President Carole Groom said the board appreciated Boesch's many contributions and the "value he has brought to the organization."