Mayor Mitch Landrieu predicted last month that he and Sheriff Marlin Gusman would have a falling out over the cost of the proposed federal consent decree for Orleans Parish Prison (OPP). It’s time for that fight to happen, and not just because of money.

City Hall and the sheriff’s office have long had a testy relationship, owing largely to the fact that the city must pay a huge chunk of the sheriff’s budget without any say in how the jail is run.

Now the stakes are much higher than money. The feds last year joined a lawsuit by the Southern Poverty Law Center (SPLC) against Gusman, alleging that he runs a jail so devoid of human decency, safety and security that it is unconstitutional. The pleadings paint a picture of a prison that rivals those of Third World countries. Some examples:

• Since January 2006, at least 39 people have died while in Gusman’s custody. An alarming number were suicides and drug-related.

• Yearly since 2008, independent experts and/or the U.S. Department of Justice (DOJ) have concluded that OPP is unsafe, unsanitary, medically unsound, poorly managed - and that’s just the beginning. Gusman denies the reports, saying they are based on “patient reports and inmate accounts.” Duh. Who else would know how bad conditions are? Last year, DOJ joined the SPLC suit to fast track the process of having conditions at the jail declared unconstitutional.

• In 2012, a review panel on prison rape singled out OPP for its “apparent culture of violence” and recommended that OPP “review the quality of the services it provides to victims of sexual assault.”

• Also last year, DOJ wrote in a letter to Gusman, “Despite our findings and repeated attempts to encourage you to meaningfully address numerous problems, the already troubling conditions [at OPP] are deteriorating.” The same letter cites “alarming conditions … [that] persist or have worsened.”

Faced with the near certainty that a federal judge will declare conditions at the jail unconstitutional, Gusman “third-partied” the mayor in an attempt to blame OPP’s horrific conditions on a lack of funding. That argument is laughable in light of the fact that Gusman maintains ancillary operations that include motorcycle, mounted, K-9, search and rescue, and security/patrol units. He spends more on fuel than the Fire Department, EMS, the district attorney’s office and the coroner’s office combined. He’s also in the process of building an $81.5 million kitchen and office facility that can serve more than 25,000 meals a day - enough for more than 8,300 prisoners, or nearly four times the jail’s current population.

Given those expenditures, it seems clear that OPP’s biggest problem is one of management, not funding.

Meanwhile, Landrieu is peeved at DOJ for potentially sticking him (and taxpayers) with a big tab for cleaning up OPP - right after he agreed with the same DOJ lawyers to pay upwards of $55 million for the NOPD consent decree. But the mayor’s predicament also presents him with an opportunity. Instead of siding with Gusman, the mayor should agree with the plaintiffs that conditions at OPP are unconstitutional - and that the city should not have to fund an unconstitutional jail. He may not win the second half of that argument, but he can join the plaintiffs in demanding that Gusman trim his ancillary operations and focus on running a right-sized jail that is safe, secure, humane, affordable, accountable and transparent. In other words: constitutional.

Landrieu has already hinted that he may ask for a court-appointed receiver to oversee the jail. That’s a good idea. (Interestingly, a citizens’ group last week suggested the same thing for NOPD. That’s fodder for another column, coming soon.)

Bottom line: This is everyone’s problem. We all know someone who has spent time in OPP, whether for long periods or just a day or two.

If we want to fight violence in our community, we have to fight violence in the jail. The relationship between a violent jail and a violent city cannot be denied. Most OPP inmates return to our streets at some point. After prolonged abuse inside the jail, is it any wonder they come out angrier and meaner than when they went in?

It’s time for the mayor and citizens to say, “Enough!”