Existing border walls have increased flooding in other areas
Presidio
The city of Presidio is commissioning an official flood-risk survey to assess the impact that a potential border wall would have on the surrounding community. John Kennedy, the executive director of the Presidio Municipal Development District, is leading the initiative with the support of the City Council as residents raise concerns about property damage and safety risks.
A barrier running parallel to the river can collect more debris, increasing the risk of flooding. This is particularly true if the barrier is built within the flood plain, as current maps of the wall indicate that it would be.
“Putting a structure in the floodplain of a flashy river seems like a bad idea, and the hydrology and geomorphology problems associated with a wall need to be emphasized,” said Kevin Urbanczyk, the director of the Rio Grande Research Center at Sul Ross University, referring to the tendency of the Rio Grande and its surrounding watersheds to experience a dangerous surge in size during minor rains.
Anyone who has waited on River Road—Highway 170 that runs along the border—to cross an arroyo knows that the area is prone to flooding after minor rains. The dusty city of Presidio sits at the confluence of four major runoff basins, with the western Chinatis, Rio Conchos, Alamito Creek and Cibolo Creek, each with its own watershed of sinewy channels, all flowing into Rio Grande as water moves from the mountains to the plains.
“The fact that all these watersheds come together here may impact the levee system,” Kennedy said in a phone call, referring to the levee system that protects the town and runs parallel to the Rio Grande. The proposed border wall would run along the levee system. There is a separate levee system along Cibolo Creek that would also be included within the study.
Presidio saw its last major flood nearly 20 years ago, when the Rio Conchos and the Rio Grande overwhelmed and circumvented the levee system at Alamito Creek, flooding downtown. Since then, levees have been rebuilt and fortified to help control future flood waters. These systems have not been fully tested as the area has experienced extreme drought in recent years.
FEMA flood maps, which are the official public source of hazard information, have not been updated since before the levees were fortified, at least 20 years ago. The International Boundary Water Commission, which oversees the flood management systems in Presidio, did not respond to questions regarding the mitigation measures currently in place or how they would be impacted by a border wall. It also has not responded to questions from local officials.
Kennedy has reached out to the Army Corps of Engineers for answers and received no reply. The Army Corps of Engineers should be required to conduct a flood risk survey of their own before construction, but with environmental protection measures waived by the Department of Homeland Security in February, it is unclear if this will happen.
“I’m sorry to say this is the backwards way to do this. The federal government should have already done this survey and brought it to us before the public comment period,” Kennedy told the City Council on April 13. The council granted its unanimous support in commissioning the flood study. Kennedy hopes to get a report focused on Presidio completed by an engineering firm as quickly as possible.
Studies in Arizona have found a significantly higher risk of flooding as a result of the border wall construction, while an engineering report in Laredo by the Rio Grande International Study Center concluded the same.
“The proposed wall and buoy system will greatly exacerbate the existing hydraulic risk by raising water levels and redirecting flows,” the Laredo report stated. “Failures will cause catastrophic flooding, damage and destruction to property, and risks to the health and safety of people near the river corridor.”’
The border wall itself is not immune to damage. In Arizona, the border wall is studded with flood gates to be opened during heavy rains, which were heavily damaged by monsoon flooding in 2021. Newer sections of fence have gates that are left open to reduce flood damage, undermining the wall’s original intent.
Here in Texas, a border barrier located along the Rio Grande between Ruidosa and Presidio suffered a different fate. The 100-foot-long steel structure measures a mere 4 feet high and is still filled with flood debris from rains that fell six months ago. The blocked barrier caused the arroyo to change course, cutting a new channel around it.