Giant tent structures have been erected in Texas to serve as short-term detention facilities to process a huge influx of families and unaccompanied minors from Central America arriving at the U.S.-Mexico border.

The facilities are open Friday in El Paso, Texas, and in the state's Rio Grande Valley next to the Donna-Rio Bravo International Bridge.

Across the Southern border, more than 103,000 migrants were taken into custody in March — the biggest monthly total in more than a decade. The Rio Grande Valley is the busiest sector. The Border Patrol reported apprehending more than 30,000 migrants in March in its Rio Grande Valley sector.

The white tent structures were built to detain migrants when they are apprehended at the border or turn themselves in to border officials. Migrant families and unaccompanied children are supposed to be detained at the facilities for no longer than 72 hours.

But immigration advocates worry migrants won't have access to legal services and medical care.

Media gathered inside the 40,000 square foot facility in Donna, Texas, which is nearly the size of a football field, for a press briefing and tour Thursday evening.

The structures are part of a $36.9 million contract awarded to Deployed Resources LLC, a New York company chosen to construct the facilities.

Border Patrol Executive Officer Carmen Qualia led press into one of four "detention pods" — each about 8,000 square feet.

The pod had high ceilings with tarp-like walls and was nearly empty. Stacks of thin-black plastic mattresses were pushed up against one wall. Qualia said the pods are also color coded.

At the intake center, there were rows of black benches and border officials behind computer.

A public information officer also showed shower areas — 18 for women and 18 for men.

Migrant families and unaccompanied children are supposed to be detained at the facility for no longer than 72 hours.

The facility is meant to hold 500 people but could hold even more if necessary. Qualia said the facility was needed.

"I hope it's enough. I hope it's enough," she said. "We would like the flow to slow down and stop all together."

Donna's mayor, Rick Morales, welcomed the facilities.

"We as small cities are not equipped to handle 2, 3, 4,000 people coming over, and we don't have those kinds of funds," he said.

The new tent structures will be temporary — four months to start with four one-month options. Morales said they need more.

"I think they need maybe 2,500 beds, 3,000 beds," said Morales.

Morales added that it's important to treat the arriving migrants humanely.

"We have to do the right thing. We're America. If we turn these people away and not take care of them properly, where else will they go?" he asked.

Temporary holding facilities aren't new for Donna. In late December 2016, during the final days of the Obama administration, a similar facility opened in the city, but it was only operational for a couple of weeks.

Back then, the detention center raised concerns among residents, immigration advocates and community leaders.

Carlos Moctezuma Garcia, an immigration attorney in the Rio Grande Valley, said in 2016 migrants didn't have access to legal representation at the holding facility, and he's worried that same thing will happen this time.

"This is the first contact they're having with law enforcement officials, and the information that they give here can later be used in whatever court proceeding that these people are going to have," Garcia said.

Garcia was also concerned about oversight and accountability issues that may arise and migrants' access to medical care, which has historically been an issue at detention facilities.

An ACLU report from 2014 found another tent structure in Texas, which was managed by a private prison company, had problems with bug infestations in the sleeping quarters, overcrowding, sewage overflows, extreme temperatures and spoiled food.

In the end, Garcia said he'd like to see border officials find alternatives to detention.

"The majority of these people are presenting themselves to a border patrol official as soon as they see them. Why? Because they want help. They're not looking to evade. So that to me tells me they will continue showing up to immigration court," he said.

The agency said migrants detained in these facilities will be released under 72 hours either to Immigration and Customs Enforcement or, if they are unaccompanied minors, to Health and Human Services for placement in a shelter or with sponsors.

CBP said they don't provide legal services to migrants at the temporary holding facility because the facility is not meant for long-term detention.

The first migrants were expected to arrive on Friday.

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