The laundry, on the north side of Rikers, serves the island and most of the city’s other jails. It already handles enormous loads and, in what turned out to be a stroke of good timing, a huge new washing machine was installed there in July. The machine, a long tube that looks like a rocket lying on its side, can do 2,000 pounds of wash every 90 minutes. The jail’s inmates were able to add extra loads from the shelters during their shifts, for which they are paid 39 cents per hour.

“With this thing, we can tackle anything,” Darrell Jennings, the superintendent of laundries at Rikers, said recently as he watched inmates load sheets and pillowcases into the machine, as well as thin wool blankets and inmate jumpsuits.

Of the city’s institutions, Rikers — which houses 11,000 inmates and has 8,500 employees — was uniquely equipped to play its unheralded role in the recovery effort. It is more than a jail complex. It is a minicity that is often referred to as New York’s sixth borough. Spread out over 400 acres, the jail has its own schools, infirmary, power plant, auto shop (with carwash), chapels, commissary stores, barbershops, bakery, tailor, print shop, and athletic fields and gyms.

The jail continues to contribute in ways small and large. On Wednesday, a shipment of food and clothing was made to a women’s shelter in the Bronx where more than 100 storm evacuees are living. And on Thursday, an association of black correction workers is delivering Thanksgiving dinner to a public-housing project in Far Rockaway.

Other correction officers have also played key roles. Some have provided security for relief centers. Others have helped unload incoming supplies at Floyd Bennett Field in Brooklyn for distribution. Some have helped to staff a medical triage center at a church in the Rockaways, while others have protected a senior residence on the peninsula whose lobby was opened as a warming center.

The jail laundry may still be used to do some shelter laundry, but it has largely returned to its normal routine of handling the department’s wash, as well as linens for the Homeless Services Department and uniforms for the Parks and Recreation Department. Jail officials did not make inmates available for interviews about the role they played in helping storm victims, but Ms. Schriro said, “I’m confident they knew what they were doing.”

While she was in the Rockaways, arranging the services that Rikers provided, Ms. Schriro heard the stories of storm victims whose lives had been upended. One of those was Tommy Corbett, a Rikers Island guard who, after the storm, divided his time among trying to fix his badly damaged house, getting his children assigned to schools that were not closed by the storm and helping other neighbors.

“His house and life was eviscerated but he was smiling and cheerful and trying to find a decent pair of boots so he could come back to work,” she said. “He was a symbol of the kind of professionals we have here.”