WASHINGTON — Conservationists and labor union officials argued Wednesday that the potential closing of the Environmental Protection Agency’s regional lab in Houston, which is expected to play a key role in Hurricane Harvey recovery, is among harmful impacts of the Trump administration’s drive to slice staff and mission in the agency.

The EPA’s Region 6 Environmental Services Laboratory, which serves a five-state region, is scheduled for closing when the lease on its rented, 41,000 square-foot space in southwest Houston expires in 2020, officials of the American Federation of Government Employees said they were told.

What happens after that, the EPA isn’t saying.

The lab employs roughly 50 people, including chemists and biologists. Much of its work has been focused on testing samples from Superfund sites in the region.

In recent days, the lab has been an EPA staging area in the aftermath of Harvey, a scientist at the lab said, adding that employees were told they can expect to do water testing during the recovery.

The potential closing raises the prospect that water or soil samples in the future might need to be sent to another EPA lab or, perhaps, tested by independent contractors. The nearest EPA regional lab is in Ada, Oklahoma, 400 miles from Houston.

At a news conference in Washington called to protest pending EPA cuts, critics said the decision to close the existing lab is ill-advised and would complicate the agency’s work in the Gulf region.

“What’s in the water coming into my house? The EPA is the agency that everybody is counting on,” said the Sierra Club's Mary Anne Hitt, referring to the agency’s role after disasters like Harvey.

John O’Grady, who heads the AFGE section representing EPA employees, called the potential closing “disconcerting.”

Speaking at the news conference, he added: “We have a laboratory in Houston that is state of the art and is situated directly in an industrial petrochemical complex. And that laboratory is slated for closure. Why? How much money are we going to save with that?”

Clovis Steib, an EPA employee and the union president in the Dallas region, said in an interview that EPA officials told him in April about the decision to close the lab.

“The sobering news given to me was that in 2019 they would start tying together loose ends and in 2020 the facility would close because they are not going to renew the lease. They would shutter it. And people there wonder, of course, what does that mean for me?”

The EPA recently offered buyouts to 12 people at the lab; three of them accepted the packages, Steib said.

Union officials visited offices of Texas members of Congress on Wednesday seeking to build support for keeping the Houston facility open.

In an email, David Gray, the EPA’s acting deputy regional administrator for Region 6, acknowledged that that the lease in Houston won’t be renewed but disputed the union's conclusions.

“We are looking at alternatives that will continue to provide the analytical services to support our mission critical work in the Dallas office,” he said.

As a candidate, President Donald Trump vowed to reduce the EPA to “little tidbits” and early in his administration proposed reducing the agency’s budget by 31 percent and cutting staff by one-fourth. Those cuts have since been scaled back by appropriators in Congress, but the reductions likely will be significant.

For years before Trump arrived, discussions took place in Washington about a change in the EPA’s approach to managing its 37 laboratories — including ten regional labs — that are housed in 170 buildings in 30 cities.

The Government Accountability Office reported six years ago that the agency had ignored recommendations dating back to the 1990s about the value of consolidating or realigning labs.

Hoping to stave off closure, Houston lab employees intend to give Congress a better understanding of what they have accomplished in recent years.

For instance, they quickly analyzed over 3,000 samples as part of a PCBs removal action at the Old ESCO Manufacturing Superfund site in Greenville, according to reports to EPA headquarters.

The Houston lab analyzed sediment samples collected in surveys of ocean-dredge sites in the Gulf of Mexico, testing for PCBs, pesticide residues and metals, among other pollutants.

For criminal cases in the region, the lab does testing both in the investigative phase and in preparation for prosecution, the report noted.

A lab employee said that the uncertainty about whether workers will have jobs or be offered transfers weighs heavily.

“We just don’t know what the future is. The stress level under these circumstances is incredible,” said the employee, who requested anonymity because employees are prohibited from speaking to reporters.