Wading into a rancorous debate that has divided City Hall and the Orleans Parish Sheriff’s Office, a nonprofit watchdog group again is urging the city to build another inmate housing facility at Orleans Parish Prison — a proposal vigorously opposed by Mayor Mitch Landrieu.

In a report published Wednesday, the Metropolitan Crime Commission warns that New Orleans will face a perilous lack of jail space and have to release scores of violent criminals or pay other parishes to house them if the city does not construct a separate building with several hundred beds in addition to the 1,438-bed, $145 million lockup expected to open in the coming weeks.

Sheriff Marlin Gusman has been a vocal proponent of building a so-called “Phase III facility,” insisting that otherwise his new complex will be too small to handle the city’s inmate population.

The sheriff, who is seeking to implement a raft of court-ordered jail reforms, has said the additional building would be dedicated to housing inmates with special needs who must be separated from the general prison population.

The Crime Commission, which released similar recommendations a year ago, urged the city to pay for the additional building with the tens of millions of federal hurricane recovery dollars that have been earmarked for public safety projects in New Orleans. The Landrieu administration reiterated its opposition to that proposal Tuesday, saying that money — roughly $50 million — would be more wisely invested in the “preventive side” of law enforcement.

“We can use it to build a jail, but we don’t need one,” said Andy Kopplin, Landrieu’s chief administrative officer. “We can use it to build a fire station, a police station, the crime lab.”

The MCC report says that even though the city has seen a 12 percent drop in its inmate population over the past year, that could be reversed by the aggressive campaign underway to hire hundreds of new police officers, who presumably would make more felony arrests.

The commission’s president, Rafael Goyeneche, said in an interview that he couldn’t “show statistically” that the jail population will increase as the New Orleans Police Department boosts its depleted ranks. But he noted that 91 percent of the jail’s inmates — a population that still includes several hundred state prisoners — either have been convicted of a felony or have pending felony charges, indicating that the jail’s resources already are devoted primarily to violent criminals.

“A healthy criminal justice system is balanced and proportionate,” the report says. “Hiring 500 more police officers without proportionately expanding capacity within the remaining criminal justice agencies sets the system up for failure and compromises public safety.”

Kopplin disputed the assertion that hiring additional officers will necessarily mean more arrests. “Police officers provide an important deterrent effect,” he said. “It hopefully will lead to increased law-abiding behavior.”

Goyeneche noted that the Phase III proposal last year received the unanimous backing of a committee of court-appointed experts who had been tasked by U.S. District Judge Lance Africk with determining the best way to provide mental health services to inmates. Representatives of both the city and sheriff participated in the committee, Goyeneche said, adding, “That’s probably the most objective analysis because each side had equal appointees.”

The MCC report calls for a total jail capacity of between 2,046 and 2,232 beds — a number it says is needed to handle the approximately 1,800 inmates now at OPP after factoring in the scores of beds that won’t be in use due to special housing assignments.

Once the Sheriff’s Office moves out of the outdated old prison, the city’s inmate capacity will fall to between 1,500 and 1,600, counting both the new jail and an overflow building known as the Temporary Detention Center, the report says. The City Council has said that building must close 18 months after the new jail opens.

The Crime Commission also weighs in on the dispute between Landrieu and Gusman over the sheriff’s controversial decision to continue housing more than 300 state prisoners at OPP even after the mayor beseeched state officials to remove those detainees. As of three weeks ago, 128 of those prisoners were participating in Gusman’s re-entry program, which is intended to reduce recidivism by preparing prisoners for their release.

The commission said the program is “consistent with” Landrieu’s NOLA for Life campaign, an initiative that has sought to reduce gang violence. “Lowering incidents of crime improves community safety and can reduce future costs associated with rearresting, reprosecuting and redetaining repeat felony offenders,” the report says.

Kopplin, however, said the housing of state prisoners amounts to “fiscal insanity” at a time when the city’s entire inmate population may have to be moved out of OPP due to its oppressive conditions — a proposition that all sides agree will be expensive. A court-appointed expert monitoring the jail reforms has recommended relocating all the inmates if the new 1,438-bed jail isn’t open by Sept. 15.

The state pays Gusman to house prisoners, but city officials say New Orleans taxpayers are essentially subsidizing the arrangement. “They are the state’s responsibility,” Kopplin said of the prisoners. “The question that taxpayers of New Orleans should be asking the sheriff is why does he insist upon doing (Gov.) Bobby Jindal’s job for him at your expense?”

Gusman has said that several dozen of the state prisoners cannot be moved to state facilities because they have pending cases in Orleans Parish, while others perform various tasks around the jail that would otherwise require civilian employees. As of last month, Gusman has said, 60 were awaiting transfer to the Department of Corrections.

Marjorie Esman, executive director of the American Civil Liberties Union of Louisiana, said the Crime Commission’s report accepts “what the sheriff says he needs without thinking about who these (inmates) are and whether they really need to be there.”

She noted that about 11 percent of the jail’s population faces pending felony charges involving drug offenses. “We can get rid of a lot of those pretrial inmates who are only there because they don’t have money” to post bail, she said.

To view the full report, go to metrocrime.org.

Follow Jim Mustian on Twitter, @JimMustian.