EL PASO, Texas — Border Patrol's largest migrant holding facility in El Paso, Texas, has been illegally disposing contaminated water into a drain that funnels water back to the city to use as drinking water for the county's 840,000 residents.

The activity has been taking place since at least April., according to the National Border Patrol Council.

Its local chapter told the Washington Examiner agents had reported witnessing several instances of workers at the El Paso Station dumping large amounts of "gray water" into an outdoor drain that sits under an awning where agents used to wash their vehicles.

"Gray water is used water. It’s not port-a-potty water, but it’s soiled water from showers and laundry facilities," a union official said during a visit to the station this week.

The union also said stations in El Paso continue to see outbreaks of scabies, measles, active tuberculosis cases, and other infectious and communicable diseases among detainees who use the showers and laundry services.

The dumping started at or before April. The federal agency has refused to provide any proof to the American Federation of Government Employees affiliate union that it has hired an outside company to come in and haul the dirty water off to a waste management site, which would indicate it is still dumping it down the on-site drain.

"We’ve had agents seen them do that," said the official.

Border Patrol's El Paso sector spokesman did not immediately respond to a request for comment.

The allegation that a federal agency is potentially violating Environmental Protection Agency and Texas Commission on Environmental Quality regulations comes three weeks since the city of El Paso launched a public campaign across several departments targeting illegal water dumpers.

The drain is located at the Border Patrol El Paso Station, under the green covering, next to the school bus. (Anna Giaritelli / Washington Examiner)

The city did not state in its May 15 campaign announcement what prompted the move or if it was due to a possible uptick found in toxic particles in the city's water reserves, which would include the dirty water Border Patrol began dumping at least a month earlier.

This specific station is home to mostly families and had approximately 1,500 people in custody this week, with up to 3,500 in custody at the sector's 10 smaller stations where migrants are also held, according to a Border Patrol agent.

A union representative pointed out the drain being used for the dumping during a recent visit to the property. The official said Border Patrol would face "huge fines" if the city found out it was secretly getting rid of the bad water this way instead of having professionals haul it off to specific plant facilities.

"They're supposed to lug it off, but they don't want to pay for it," the union representative said.

Border Patrol's El Paso region is holding far too many people in enclosed spaces for significantly longer periods of time than it it supposed to, according to a Department of Homeland Security Office of the Inspector General report released this week. The report stated some El Paso sector detainees were wearing soiled clothes and were being held in unsanitary conditions.

Customs and Border Protection told the inspector general it has not been able to meet internal standards and transfer people to other agencies within 72 hours because those other agencies are overwhelmed and cannot accept new detainees as quickly as Customs and Border Protection needs to release them.