WASHINGTON– On one hand: a small community in rural Texas. On the other: the Trump administration.

A small Texas town along the border with Mexico is fighting the government’s efforts to build a border wall across a levee system to protect the community. The city argued in court Tuesday that the wall could cause flooding and that the administration is not following the law as it moves forward with its plans.

The hearing in federal court came as the Department of Homeland Security moves forward with its $46 billion plan to complete a border wall from the Pacific Ocean to the Gulf of Mexico and fulfill what has long been a signature promise of President Donald Trump. But the department faces opposition from landowners, environmental groups, Native American tribes and others who argue that the government’s rapid construction endangers historic and religious sites and a way of life along the border, when crossings from Mexico are already at extremely low levels.

The lawsuit filed by the Presidio Development District pits a small town of just over 3,200 residents against a department key to the Trump administration’s plans to carry out its mass deportation agenda. It also shows a context that has long been important to many Americans, particularly Republicans: the irritations that sometimes arise between more local municipalities and the federal government in Washington.

Lawyers for the development district argue that the government’s plans could compromise the levee system that protects the city from flash flooding – a formidable problem in Texas – and that the government violated a key law that requires it to ask permission from the Army Corps of Engineers before building on or near levees.

The government maintains that there is no final plan for where the border wall will be located or how it will be built. Still, the administration says it has the authority to waive a wide range of regulations to build the wall, as it seeks to reduce the number of people crossing the border every day to zero.

The city is concerned about the effect the wall would have on a series of berms and levees built in the 1970s and 1980s along the Rio Grande and its tributaries to combat flooding.

In court documents, the Presidio Development District said Customs and Border Protection plans to “replace the earthen slope of the existing levee with a concrete wall, with 30-foot steel bollard panels installed on top.” The district says it asked the agency for more details, but was told they cannot be shared due to “national security.”

“Unfortunately, there is a long history here of CBP construction causing or increasing flood risks,” said Laura Bakst, an attorney with Democracy Forward, which represents the Presidio development district in the case.

A government lawyer said during Tuesday’s hearing that it’s too early to argue that the proposed wall could harm Presidio because Customs and Border Protection hasn’t actually decided on a final plan for it.

In the race to build the wall, both former Homeland Security Secretary Kristi Noem and current secretary Markwayne Mullin have waived numerous environmental or archaeological site protection requirements that the federal government normally must follow when building infrastructure projects.

Under legislation passed by Congress, Homeland Security has the authority to waive certain requirements specifically to accelerate the construction of walls along the US-Mexico border. But critics argue that the department is going much further than Congress intended by issuing broad waivers along the 2,000-mile or 3,200-kilometer length of the border.

In the case of Presidio, the development district argues that Homeland Security is in conflict with the Rivers and Harbors Law. The department has waived it, but Presidio’s lawyers argued that because of the wording of the Act, Homeland Security still had to consult with the Army Corps of Engineers before launching the project.

Louis Katz, an attorney for Democracy Forward, warned that the way the department was waiving state and federal laws as it moved forward with the wall is an “extraordinary exercise of authority.”

One key question: When would construction begin? Timing has been an issue beyond the Presidio as landowners up and down the border search for an answer. Construction crews have previously placed supplies, including steel bollard wall panels, but no wall construction has begun in the area.

A Justice Department lawyer gave insight into the government’s timeline. In response to questions about whether construction could begin in early August, Alexander Yun told the judge it was unlikely to begin that early. Yun said construction could begin in late August, September or October.

The Department of Homeland Security has indicated that building the wall is a priority.

Mullin said during congressional testimony in June that the preliminary layer of the wall will be finished “this time next year.” Customs and Border Protection Chief Rodney Scott has said the agency is building 10 kilometers (6 miles) of wall per week.

The Trump administration is pushing for the wall when border crossings are at the lowest levels in decades. The Big Bend sector has not experienced the large number of border crossings seen in recent years in other areas further south along the Rio Grande or in Arizona or California, due to the remote and challenging terrain on both sides of the border.

But the Justice Department lawyer said the low numbers of border crossings seen over the past year are an “anomaly” and that the goal is “zero illegal crossings.”

Judge Reggie Walton scoffed at that idea, saying it is “simply a reality” that people will always try to cross the border.

Walton also said he was wrestling with the question of how much authority he had to limit the department considering that Congress had given him the ability to waive certain requirements.

The judge said he would issue a ruling next week.