President Trump’s quest to build as much of his border wall as possible before leaving office is newly angering landowners and authorities in the American southwest.

An Arizona rancher said construction crews recently detonated explosives that sent “car-sized boulders” tumbling onto his property. Municipal water officials in El Paso said they deployed dump trucks last week to block wall-builders from cutting off their only road to a vital canal along the Rio Grande. And landowners in Laredo, Tex., are urging elected officials to pressure the incoming Biden administration to make clear that their private property will be safe from construction crews eager to finish the job.

The feuds demonstrate the impact that Trump’s final push to expand his $15 billion border wall is having on a region that has been the focal point of his four-year term, even though President-elect Joe Biden has pledged to stop construction immediately upon taking office. Federal officials say Trump has built 415 miles of new barriers — and that they expect to reach 450 miles by the end of the year while working at breakneck pace — to deter drug traffickers, human smugglers and criminal organizations from attempting to enter the United States. But critics say the wall is a political boondoggle and that the administration is trampling landowners’ rights in the process of building it.

The most recent flare-up last week in El Paso pit the county’s water district against the federal government and a construction crew from Oklahoma.

Jesus “Chuy” Reyes, general manager of the El Paso County Water Improvement District, an elected board that owns and operates hundreds of miles of canals and drains, said he learned on Nov. 10 that a construction crew was planning to build a three-mile stretch of wall in the Texas border community. The wall would be parallel to an existing wall that the Trump administration rebuilt two years ago and topped with razor wire. The older fence had cut off the south access road to the American Canal Extension, a public works project that allows Mexico and the United States to share the waters of the Rio Grande.

Reyes said he did not know where the second wall would go, but last week he spotted it: Heavy machinery was being used to dig a trench in the middle of the only other access road to the canal, on the north side. It was about 70 feet away from the old wall.

Furious, he deployed a pair of dump trucks to block the road. Then, he wrote to the U.S. Army Corps of Engineers, which oversees the private companies building the barrier.

“For a host of reasons, some of which should be obvious, this is not acceptable and directly interferes with the District’s operations and authority and duties under state and federal law,” he wrote to Army Corps Col. Antoinette R. Gant, according to a copy of the letter provided to The Washington Post.

The district maintains and operates the canal extension, which supplies drinking water to the Texas border county of 800,000 people and irrigation for thousands of acres of cotton fields and pecan orchards, he said. The water district needs 24-hour access to it to make repairs, adjust the gates and to rescue people who fall in.

In a heavy storm, for example, the district must quickly open the canal gates to prevent rainwater from overflowing into nearby neighborhoods.

Reyes said he believes federal officials were plowing ahead without regard for border residents, whose homes, roads and schools are nearby. He said he pressed an Army Corps official for answers in a meeting last week, and he was left with the impression that the push to build was “most definitely part of the Trump administration’s effort to build as many miles as they can.”

“She said, ‘We only have a certain amount of time to build this,’ ” he recalled. “We plainly asked her, ‘Is this part of the Trump fence you need to finish by January 20th?’ She said, ‘The only thing I can tell you is the orders are coming from Washington.”

The Army Corps confirmed that water district photographs depicting the freshly dug trenches were accurate, and then said that construction on that section has stopped.

“The U.S. Army Corps of Engineers is sensitive to the El Paso Water District’s concerns,” spokeswoman Raini Brunson said. She said the Army Corps is coordinating with CBP and the U.S. International Boundary and Water Commission to consider “shifting” that segment.

Reyes said if they do not move the wall, the water district would sue.

“It’s very frustrating because we know that they want to build it before January 20th,” he said. “We’re not dumb.”

Benham, a Haskell company that Reyes identified as in charge of the construction project, did not respond to a request for comment.

U.S. Customs and Border Protection spokesman Roger Maier said the agency is working with the Corps as well as the U.S. International Boundary Water Commission, the federal agency that enforces the boundary and water treaties of the U.S. and Mexico, “to ensure that there is continued access to the canal for water supply delivery, operations and other maintenance activities during and after construction.”

The dispute is in many ways emblematic of complaints that have flared along the nearly 2,000-mile border, where advocates say construction crews have damaged wildlife habitats, portions of saguaro cactus forests and private property.

In Cochise County, Ariz., a remote and rugged border region, ranch owners often have friendly relationships with the Border Patrol, sharing the codes to the locks on their gates so that agents can patrol freely. And the agents frequently assist local authorities in emergencies.

The owners of Diamond A. Ranch say they were trying to cooperate with authorities to ensure the border barriers would secure the area and preserve wildlife corridors running from the Sierra Madre in Mexico to the U.S. Rockies. But those relationships soured in recent months as a “small army” of construction vehicles arrived in the summer to build the wall, they said. Massive explosions and jackhammers soon followed.

The ranch owners filed a lawsuit Monday against the Department of Homeland Security in U.S. District Court for the District of Columbia urging a judge to halt the construction, saying that rocks and debris are jeopardizing their safety and arguing that the wall could increase the risk of flooding. They said they also are concerned that explosions to clear rugged territory will endanger the Guadalupe Canyon, home to wildlife such as jaguars, ocelots, rattlesnakes and the Chiricahua leopard frog.

In the lawsuit, ranch owners say construction crews have entered the property without permission and have used explosives “so aggressively that the blasts sent clouds of dirt, shrapnel and car-sized boulders tumbling down” onto their property from Roosevelt Reservation, a slice of neighboring federal land.

“Plaintiffs are not making a political statement,” the lawsuit said. “They support and depend on strong border enforcement, and they have maintained good relations with the Border Patrol for decades. But officials dispatched from Washington to build the wall have unconscionably abused Plaintiffs’ trust.”

Stewart Baker, the ranchers’ lawyer and a former top Homeland Security official in the George W. Bush administration, said the push from the White House is affecting CBP’s relationship with some border residents.

“A lot of people on the border have heard and seen this,” he said. “CBP has hurt its relationship with the community.”

Some along the border also are raising concerns about Biden, who has pledged to stop construction but has not clarified how he will cope with the costs of terminating the projects. Landowners say they are hoping for clearer assurances from the incoming president that their properties will be safe.

Crews have been working around-the-clock at several points on the border to install as much of the 30-foot steel bollard fencing as possible before Trump leaves office. The companies will be entitled to compensation from the Biden administration for the costs of withdrawing crews and equipment, but the contracts have a termination clause that allows the government to back out, according to the Army Corps.

Biden has promised not to expand the wall, but his transition officials may not learn for several more weeks what the termination costs would be.

Advocates in Laredo say they are pressing the incoming Biden administration to make clear that their land will be safe from officials and construction crews eager to finish the job, said Ricardo de Anda, a Laredo lawyer who represents landowners fighting Trump’s efforts to seize their land. He said he belongs to anti-wall groups that are lobbying local governments to pass resolutions that would urge the Biden administration to keep its promise to halt the wall and overturn measures that paved the way for it.

“We’re under the gun here,” de Anda said. “The thing is, on January 21st, it becomes his problem. It will then become the Biden Wall, so the clearer he is now, the less of a problem it will be.”

Nick Miroff contributed to this report.