(Updated Wednesday 5:15 p.m.) The Department of Corrections will be closing Bergin Correctional Institute in Mansfield, Office of Policy and Management Undersecretary of Criminal Justice Michael P. Lawlor said Tuesday morning.

The closure is one of the more serious options Gov. Dannel P. Malloy presented as part of his “Plan B” budget if he doesn’t get the $2 billion in concessions he needs from the state employee unions, Lawlor said.

Senate President Don Williams, whose district includes Mansfield, said Wednesday that as part of the “Plan B” budget, the facility’s closure hinges on a labor agreement.

“If there’s an agreement between the administration and the state employees then it’s possible that this decision will be reversed and the layoff notices will be rescinded,” he said.

Williams said the labor talks are still ongoing but said he hopes an agreement is reached soon as there is a lot riding on that agreement.

The decision to close the facility comes on the heels of a Tuesday morning statement from Malloy, directing the Office of Policy and Management to mail layoff notices to 4,742 state employees.

Bergin, expected to close July 1, will become the second prison closed this year.

The department announced last month that J.B. Gates Correctional Institution in Niantic will be closing June 1. Lawlor said there likely will be a third prison closed but he did not speculate on which facility will be shuttered. Many believe the third facility is likely to be Enfield Correctional Institution.

It’s unclear how many people will be laid off as a result of the Bergin closure but according to the DOC’s website, the facility currently has 218 staff members. Records say the facility housed 931 inmates Jan. 1.

On Tuesday, Lawlor said the state has experienced a rapidly declining inmate population over the last few years. The population peaked in February 2008 around 19,900 shortly after then-Gov. M. Jodi Rell temporarily banned parole hearings. Today that number is around 17,400, Lawlor said.

The news of Bergin’s planned closure came as a surprise to some union leaders. Reached by phone, AFSCME Local 1565 President Luke Leone said he was shocked. Leone’s union represents 90 percent of the state’s prison employees.

On Tuesday, he said that when the state announced the plan to shut down J.B. Gates, Correction Department Commissioner Leo Arnone said Enfield Correctional Institute would be next.

Leone said the closure of Bergin will necessitate significant changes for both the department’s staff and the inmates. For instance, he said some male inmates currently housed at Bergin will be moved to York, the state’s only female prison. This move will create the only co-ed correctional facility in the state.

Because of space issues, some of the female prisoners will be displaced and will have to sleep in the facility’s gymnasium, he said. According to the department’s website, York housed 1,031 female inmates as of Jan. 1 and had a staff of about 500.

Revelations of the closure inadvertently coincided with the launch of a new media campaign by AFSCME Locals 387, 391 and 1565. The campaign is aimed at raising awareness of public safety concerns created by closing state prisons to save money, according to Larry Dorman, spokesman for SEBAC.

The unions are raising billboards at four different locations on state highways — two in Hartford, one in New Haven, and another in Waterbury — Dorman said. The billboards read, “Connecticut Prisons Closing. 2,000 inmates released. Money Over Safety.”

The campaign also will include a radio spot that was scheduled to begin airing on WTIC on Wednesday.

“Guess what?” the radio spot’s narrator asks, “the state wants to shut down even more prisons. That can only mean more criminals coming to a street near you.”

The “2,000 inmates released” statement refers to prisoners released under diversionary programs, Leone said. He noted that a bill pending before the legislature is aimed at decreasing the inmate population through additional programs.

The measure, part of the Malloy administration’s legislative recommendations, would allow some drunk driving offenders facing a mandatory prison time to serve their sentences under strict house arrest.

It also would authorize the Correction Department commissioner to award some inmates risk reduction credits for good behavior and participation in programs aimed at easing the transition back in to the community. The incentive credits amount to small reductions in prison sentences.

The policies would help refocus the state’s criminal justice system towards violent and serious offenders, Lawlor told the Judiciary Committee at a public hearing in March.

Leone did not comment on the virtues of either proposed program but said it was dangerous for the state to release prisoners to save money. He did recall the 2007 triple-homicide in Cheshire. Many believe that incident could not have occurred if not for a lack of oversight in the state’s parole system.

“God forbid we have something happen like what happened in Cheshire,” he said.