New York City’s borough-based jails — which are meant to replace Rikers Island — will house hundreds more detainees than previously planned, Gothamist has learned.

The four planned jails for Brooklyn, the Bronx, Queens and Manhattan will each have room for 1,040 beds, according to documents provided to Gothamist. The city last year announced plans to expand the Brooklyn jail’s capacity from a previously planned 886 beds up to that number — and city officials on Thursday confirmed that the other three jails will follow suit.

That puts the total capacity of the four new jails at 4,160, but that’s still not enough space to move out all the roughly 6,000 current detainees at Rikers Island.

As the city prepares to relocate its jails, it is fighting in court to stop a potential federal takeover of Rikers. Thirty incarcerated people have died in city custody since Adams took office at the start of 2022. The federal monitor who oversees Rikers has alleged city officials have failed to properly manage the system.

But Adams' office took a jab at his predecessor when asked about the capacity expansion.

Adams' spokesperson Liz Garcia said in a statement that “it [became] painfully clear” the borough-based jails plan approved under former Mayor Bill de Blasio “leaves open serious questions about the city’s ability to keep New Yorkers safe.”

“The number of beds in each of the four facilities reflects an honest accounting of the realities of the criminal justice system and public safety in our city, including maintaining critical services for those in custody,” Garcia said.

City officials did not explain how they might either add more space or reduce the city's incarcerated population.

The new jail capacity was first referenced in a document provided through a public records request from the advocacy group Freedom Agenda.

The Department of Correction has estimated it will hold 7,000 pretrial detainees by next year. The new jails' designs were originally conceived in 2020, when the department’s incarcerated population was at a historic low of roughly 4,500 people.

The jails' physical sizes are not allowed to grow from previous plans. In order to hold more people, all of the facilities will contain fewer of the spacious, specialized units intended for detainees with mental illness or substance abuse disorders, according to Zachary Katznelson, executive director of the Independent Rikers Commission, which the city created to help with the closure of Rikers.

Katznelson said the fact that the number of planned detainee beds at three city hospitals has been reduced from 400 to 363 compounds the lack of space for detainees with mental illness or substance abuse disorders, who make up a majority of the city's jail population.

There should be more substance abuse and mental health treatment options outside of the jails in communities for those charged but not yet convicted of crimes, according to Katznelson.

“The reason a judge is very often ordering them being held is they want to make sure they get that treatment,” he said. “So if we had different options in the community, we could have different outcomes.”

Katznelson also recommends increasing the pace of criminal cases moving through the court system, and ordering those awaiting trial to be electronically monitored instead of jailed.

“We think we can bring that population down significantly without harming safety at all,” he said.

Rikers Island is legally required to close in 2027. But the construction of the borough-based jails intended to replace the decrepit facility is already behind schedule and more expensive to build than originally projected.

The new plans include tripling the number of beds for female detainees from — 126 to 450 — at the Queens jail in Kew Gardens. That facility is the only borough-based jail that will be built to house incarcerated women.

The ​​Women’s Community Justice Association, which developed a plan to reduce the number of female detainees in all the city’s jails to fewer than 100, sent Mayor Eric Adams a letter on Thursday after learning of the plan to house more women at the Queens site, in which it called the move “baffling” and “unconscionable.”

The association's executive director, the Rev. Sharon White-Harrigan, said women have special needs — “physically, mentally, spiritually” — that have historically been ignored in jail settings. She pointed out that most incarcerated women have been victims of abuse.

Jail chaplain Victoria A. Phillips, another detainee advocate who signed the letter to the mayor, said women should have their own facility where they don’t risk contact with male detainees. She also said Adams’ recent $17 million in cuts to programming at Rikers will only worsen women's experiences.

“It’s the baseline for recreating the culture that we have for so many years pushed to end at New York City’s Department of Correction,” Phillips said.

Plans to increase capacity at the borough-based jails are also fueling local opposition. Alfred Brand, chair of the Kew Gardens Civic Association, said the city should consider overhauling Rikers Island with new jail facilities.

“We believe that the whole program of borough-based jails does not meet the needs of the confined individuals or the city as a whole,” he said. “This is a big problem that the city is failing to address on a comprehensive basis.”

Correction: Due to an editing error, a previous version of this story misspelled Rev. Sharon White-Harrigan's name.