A three-mile stretch of privately-funded border wall, built by a Trump supporter along the edge of the Rio Grande River, is at risk of collapsing and falling into the river, according to a new report by Pro Publica.

Touting a new construction technique that allowed him to build the $42 million fence on the river bank, Tommy Fisher leveraged his initial project into a $1.3 billion federal contract to build other sections of border security.

But according to engineers and hydrologists who reviewed photos of the wall for ProPublica and The Texas Tribune, the structure shows significant signs of runoff erosion that will cause the fence to tumble into the river if it’s not constantly repaired and upgraded.

“When the river rises, it will likely attack those areas where the foundation is exposed, further weakening support of the fence and potentially causing portions … to fall into the Rio Grande,” Alex Mayer, a civil engineering professor at the University of Texas at El Paso, told Pro Publica.

Through his company’s attorney, Fisher dismissed any such concerns, but other similar projects he’s undertaken have been criticized for similarly shoddy construction practices.

The Army Corps of Engineers has stated that Fisher won the federal contract because his bid was the least expensive, although some questions have been raised if he used political influence with republican North Dakota Senator Kevin Cramer and connections to the Kushner family to gain an advantage.