A team of nonprofit agencies began working Tuesday to find new homes for dozens of homeless people living underneath the Pontchartrain Expressway. The action followed issuance of a city notice ordering the area cleared of people and cars within 72 hours.

In an advisory posted Monday night, the city called the area under the expressway between South Claiborne and St. Charles avenues a public health hazard.

Health Director Charlotte Parent said Tuesday that it needs to be vacated so that it can be cleaned and treated for rodents.

A growing number of homeless residents have been using the area as an encampment, outfitting it with tents and even couches. As their numbers have grown, so has the amount of refuse under the expressway, Parent said.

The swelling population also has led to an increase in complaints from Warehouse District residents and motorists who drive by the camp.

The Department of Health’s order says the New Orleans Police Department will monitor the area and tow any vehicles that are not removed by their owners.

Parent said the advisory became necessary after ongoing assessments by the Sanitation Department, Health Department and Mosquito, Termite and Rodent Control Board determined that the area was hazardous. Employees from those offices have been cleaning up around the encampment and putting out bait for rodents, but the rapid accumulation of food and debris made it impossible to clean it adequately, Parent said.

“Our intention is to clear the area so city departments can adequately remove debris, treat the area for rodents and thoroughly clean it to decrease public health concerns,” she said.

The process of cleaning out the area will take less than a day, Parent said, but public access to the space will continue to be restricted by police barricades. Police also will monitor the site.

It is unclear when or if it will be reopened.

“We are going to barricade off the area until we work through a permanent solution for that site,” Parent said.

The city said it is working with UNITY of Greater New Orleans, a nonprofit coalition of 60 agencies working to end homelessness in Orleans and Jefferson parishes, to find alternative housing for people who are displaced.

UNITY announced in May that the two parishes had made tremendous strides in reducing the homeless population.

On a typical night this year, UNITY said, a survey found that 1,981 people were living in temporary shelters, on the streets or in abandoned buildings in Orleans and Jefferson parishes. That was down from the 2,337 people found to be homeless last year. The federally mandated count of the city’s homeless population was conducted March 31.

An estimated 140 to 150 people were living under the expressway when Monday’s order was posted, Parent said. They have been warned to remove all personal property from the encampment by Thursday night.

Enough “space for anyone who chooses to take that space” has been identified at four area shelters — the Salvation Army, New Orleans Mission, Ozanam Inn and Covenant House — to accommodate people who are displaced, the city said.

“We know that homelessness is a big issue,” Parent said. “We’re trying to be empathetic to what we need to be empathetic to, but the bottom line is that when the departments can’t do the work that they need to do to create a safe public health space, then we need to act.”

The city’s order came as the volume has been raised on complaints from residents about the growing homeless population under the expressway.

“I think that’s wonderful that they did something,” Warehouse District resident Kevin Kelly said. “I don’t know what took so long.”

Kelly said the transient community has been a growing concern for residents who say there has been an uptick in violence near the expressway.

“It’s dangerous,” he said. “It makes people afraid to walk around. It makes people fearful of walking around downtown for fear of getting hurt.”

A man was arrested and booked with attempted murder last week after undercover State Police troopers spotted him firing a gun at someone under the expressway.

“We can’t have people living under the expressway,” said Cassandra Sharpe, who sits on the board of the Lafayette Square Association and has been leading a charge to have the camp shut down. “Somebody has to take responsibility.”

Sharpe pointed to the shooting incident as an example of the danger the area poses to residents. Before Monday’s notice of evacuation went out, tents shared space in the camp with a growing number of furniture pieces such as living room sofas and chairs.

Parent conceded that the area had become “somewhat out of control.”

“But the bigger issue for me is the public safety and the health of the citizens that are there,” she said.