The King County coordinator for treating mentally ill residents against their will has resigned following scrutiny of how her team failed to meet legal deadlines, resulting in hundreds of dangerously sick patients being released without care.

The Aug. 1 departure of JoEllen Watson adds another burden to the county Department of Community and Health Services as it scrambles to comply with a recent state Supreme Court order to stop temporarily detaining patients in hospital emergency rooms, a practice known as “psychiatric boarding.”

Because of a severe shortage of mental-health-treatment facilities, King County has been boarding 90 percent of detained county patients in ERs. They stay an average of three days, often tied to gurneys to prevent injury.

Watson agreed to resign, not sue the county and not seek future county employment in return for a neutral reference letter and the removal of a reprimand letter from her personnel file, according to a settlement signed in early June.

The settlement came two weeks after Watson was placed on administrative leave so supervisors could review issues raised in a Seattle Times investigation, county spokeswoman Sherry Hamilton said.

The May 5 article revealed that every other day, on average, a resident classified by the county as dangerous was getting released due to missed deadlines. State law requires that all forcibly detained mental patients be assessed by a county official within six to 12 hours of being held.

The investigation also showed that officials had never measured the problem nor notified the state about it. The county also violated the state Public Disclosure Act by not releasing hundreds of pages of emails about the problem requested by The Times.

The county eventually paid the newspaper $41,560 in legal fees and penalties to avoid a lawsuit, and reprimanded Watson, as well as public-records officer Sharon Logue.

Even so, Watson’s departure surprised many of her former colleagues, longtime co-worker Christie White said. “There was no explanation,” she said.

Charlie Huffine, a psychiatrist who worked with the team part time, said Watson did an admirable job with a difficult assignment.

“There was so much pressure — people showing up at emergency rooms, and everything else,” Huffine said. “I think she did the best she could.”

The 32-employee team evaluated 6,124 people last year and detained 3,159 of them, officials said.

The unit is being run temporarily by Watson’s former boss, Jean Robertson, who also oversees all county mental-health programs. Officials said they hope to promote someone into the job permanently next month.

Robertson’s boss, Jim Vollendroff, who took over King County’s mental-health and drug-abuse division in February, said at the time that his two top priorities were ending psychiatric boarding and halting patients being released because of missed deadlines.

Watson, who has a doctorate in social work from the University of Washington, became the county’s involuntary-commitment coordinator in July 2007 after working in other jobs in the department since 2002, according to the county’s neutral reference letter. Watson’s salary when she resigned was $112,825.

Other than the notification about the administrative leave, there are no records of disciplinary actions or performance issues in Watson’s 387-page personnel file.

The reprimand letter removed from the file criticized Watson for “lack of judgment and/or noncompliance” in failing to provide emails requested by The Times.

The settlement bars Watson and the county from discussing the deal or criticizing each other. Both sides declined to comment.