Fresno County jailers are working more overtime than they have in years, which some fear may be a threat to safety.

The amount of overtime worked by correctional officers during the past nine months is more than double what it was during the same period a year ago, according to a review of County Jail pay records.

The jail's 315 correctional officers are putting in, on average, nearly 14 extra hours of work every two weeks, on top of their regular 84-hour shifts.

While the Sheriff's Office actually saves money by not hiring new employees -- the rate of overtime pay is less expensive than offering new benefits -- jail administrators acknowledge that their work demands are unsustainable, and an unprecedented hiring effort is under way.

In the meantime, correctional officers are complaining about long hours, and their union reps allege that employees are at greater risk of fatigue and making mistakes on the job.

"There's a number of hours worked that, when an officer gets past it, it's unsafe for them and other officers," said Tom Abshere, a former correctional officer and currently the director of the local chapter of Service Employees International Union. Abshere did not identify what amount of work was too much, saying it varied with the individual.

But with jail officials already releasing inmates early because of a lack of space, the Sheriff's Office can hardly afford to cut back any employee schedules.

"We're working hard to fill the vacancies," said Sheriff Margaret Mims, "but without the use of overtime we wouldn't be able to keep the floors open that we're keeping open."

The staffing shortage comes in the wake of Gov. Jerry Brown's downsizing of the state prison system. Under the governor's prison realignment, enacted with Assembly Bill 109, state prisons are holding fewer inmates and county jails are picking up the slack.

"The main problem with where we're at right now is that AB109 happened so fast," Mims said. "We didn't have time to build capacity as far as our facilities go, as well as build capacity with our staff."

In October, just months after AB109 was signed into law, the sheriff opened one of three floors in the jail's north annex, which had been closed for three years because of budget cuts. The 432-bed floor, meant to help house the realigned inmates, requires 23 full-time positions to operate.

The county got extra money from the state to hire new correctional officers and has added about 50 in the past nine months. But many are still in training. Meanwhile, more than 20 veterans have retired or quit -- an unusually high attrition rate, according to administrators.

As a result, the new jail floor has been staffed largely with employees working overtime shifts.

Since October, correctional officers have regularly logged more than 4,000 total overtime hours during the jail's two-week pay periods, according to the records. That equates to nearly 48 full-timers (based on 84-hour work periods).

The salary of a correctional officer starts at about $35,000 annually and tops out just above $60,000. But with overtime pay, which is paid out at time and a half, many make more than $100,000 a year.

Several correctional officers, all who spoke on the condition of anonymity, said the overtime initially was welcomed as a way to make extra cash, but most said they're tired of it now.

Because of the staffing shortage, nonessential business at the jail, such as visitation and commissary deliveries, has been scaled back. And often, newly arrived criminals are put in holding cells instead of being booked into the jail -- until there's enough staff to do the bookings.