An influx of state prisoners coupled with a shortage of correctional deputies could soon prompt Sonoma County officials to start shipping jail inmates to Marin and Mendocino counties.

Already, Sonoma County is sending minimum-security male inmates to Alameda County, where jail officials have agreed to take up to 100 inmates at a time.

Now, it could expand transfers to its northern and southern neighbors along the Highway 101 corridor in a deal that was finalized last month.

Marin County and Mendocino County each have agreed to accept up to 15 inmates for $100 a day per inmate in an arrangement that could generate $547,000 a year for each county. One Marin County supervisor likened the situation to mutual aid among law enforcement agencies.

“Except mutual aid is free,” Marin County Sheriff Robert Doyle said. “And this is not free.”

Sonoma County jail officials said they had no choice but to send inmates elsewhere and pay the money. Randall Walker, the assistant sheriff for detention, said portions of the north county facility remain closed because of ongoing staff shortages caused by a combination of retirements and layoffs from about five years ago.

The situation has been worsened by new inmates arriving since 2011 under the state’s realignment program, which is designed to reduce prison overcrowding by shifting lower-level offenders from state prison to county jails. Realignment has increased the jail population in Sonoma County by 13 percent to 15 percent, Walker said.

Current capacity of the honor farm and the Main Adult Detention Facility combined is 1,186 inmates, he said. Any additional inmates must be farmed out to other counties, he said.

“Realignment was not the cause,” Walker said. “But it did add to the pain.”

He approached Solano County jail officials, too, but they were not able to accommodate more inmates.

Now, he said, 66 inmates are serving sentences in Alameda County and others could go to Marin and Mendocino counties.

The shortage of correctional deputies in Sonoma County started with recession-era cuts. The jail has since hired about 40 people in the past 18 months and is actively recruiting to fill remaining vacant positions, he said.

In the meantime, correctional deputies are required to work mandatory overtime, up to 60 hours a month. Payroll records from 2013 show correctional officers were paid about $4 million in overtime alone.

Walker said shelling out overtime is less expensive than hiring new deputies, but it takes a physical and emotional toll on employees that could add to attrition.

Once enough deputies are hired, the inmates will come back. Walker said that could happen in less than a year.

Last week, the total jail population was just over 1,100, Walker said.

“It takes a while to get out of the hole,” he said.

News researcher Janet Balicki contributed to this story. You can reach Staff Writer Paul Payne at 568-5312 or paul.payne@pressdemocrat.com. On Twitter @ppayne.