Police confront protesters at the corner of 13th and K streets NW on the day of President Trump’s inauguration. The federal government reimbursed the District for overtime run up that day by public safety agencies. (Sarah L. Voisin/The Washington Post)

The District government’s spending on overtime for public employees more than doubled between 2011 and 2017, according to a new report from the Office of the D.C. Auditor.

Overtime spending gradually increased from $40.5 million during fiscal 2011 to $108.2 million in fiscal 2017, auditors found. Much of that boost was concentrated at public safety agencies, with just four — the police department, Fire and Emergency Medical Services, the Department of Corrections and the Department of Youth Rehabilitation Services — accounting for nearly 70 percent of the increase.

Auditors recommended that District agencies hire more full-time staff to avoid the need for overtime and more tightly monitor their payrolls.

“The use of employee overtime is a necessary tool for every government, and especially important for public safety agencies,” D.C. Auditor Kathy Patterson said in a written statement. However, she said, stronger internal controls and adequate staffing “would help minimize the use of overtime and save District taxpayer dollars.”

In addition to the cost, the report states, too much overtime work can erode public employees’ ability to do their jobs well. “Excessive overtime means some District employees are working longer hours on less rest, creating a higher risk of inattentiveness that can lead to injury to themselves or others, and potentially threaten to undermine an agency’s mission,” the report says.

Auditors’ calculations did not include at least $4.66 million the federal government reimbursed the police and fire departments for overtime during the 2017 presidential inauguration and the Women’s March. The auditor’s office said in its report that it could not verify the specific reimbursement amounts.

Hundreds of government workers are making much of their money through overtime, the report states, including 41 who received more than half their overall pay through overtime in fiscal 2017 and an additional 380 who received at least a third of their pay through overtime.

Among the causes of overtime spending have been regular raises for government workers — which increase the calculation of overtime rates. Another likely factor cited by the report was the District’s rollout, beginning in fiscal 2015, of an expansive program of paid family and medical leave for public employees. (Similar guarantees for private-sector workers were approved in late 2016 but have not been implemented.) To cover for workers using their leave, public-safety agencies may have assigned other employees to work overtime, the report states.

The audit also found chronic and unexplained employee absences at the Department of Youth Rehabilitation Services, with more than 9,200 hours of such absences in fiscal 2017, the equivalent of 1,151 eight-hour shifts when workers failed to show up.

The public safety agencies that were the focus of the audit largely agreed with the recommendations for tighter controls, the report states.