The Los Angeles County Board of Supervisors on Tuesday unanimously appointed Bruce Chernof director of the troubled County Department of Health Services, effective immediately.

Chernof, 43, had served as acting director since November, when then-director Thomas Garthwaite resigned amidst a long-running scandal at King-Drew Medical Center and the looming threat of a massive budget deficit.

Chernof, who was the department’s senior medical director for clinical affairs since late 2004, now becomes the third county health chief in four years. Prior to that, Chernof was regional medical director for health programs at Health Net, one of the state’s largest HMOs.

He inherits a department in turmoil. In the short run, the department faces a $66 million deficit for the fiscal year beginning July 1. But that’s expected to swell to at least $850 million in three years as federal aid is set to expire, leaving the county to care for the increasing ranks of the uninsured.

Meanwhile, at King-Drew, Garthwaite was unable to make much headway in fixing mismanagement and a string of patient deaths over the last decade. He brought in Navigant Consulting to try to fix the problem, but the outside management firm has had problems of its own.

These problems have fueled discussion to split the massive agency with its 22,000 employees and $3.7 billion budget into personal health and public health departments.