Mexican officials say a concrete barrier constructed by the U.S. Border Patrol in a storm-water tunnel beneath Nogales appears to be on Mexican soil and was the main cause of serious flooding July 12 in Nogales, Sonora.
The flooding caused about $8 million in damage in Nogales, Sonora, the officials say.
The 5-foot-high wall on the floor of the tunnel in front of a gate was put in without notifying the International Boundary and Water Commission, said Sally Spener, spokeswoman for the U.S. section of the commission. The commission requests that any agency doing work on the border that could affect storm drainage send it plans.
The U.S. side of the commission hasn’t yet determined if the barrier caused the flooding, Spener said. It’s important to remember the Mexican side of the tunnel was old and in poor condition, she said.
Officials with the Mexican section of the commission say the barrier reduced the flow of storm water through the tunnel by 40 percent, said Jesús Quintanar, a representative in Nogales of the Mexican side of the commission. The barrier was put up in January by the Border Patrol without letting anyone else know, he said.
Although built in the 1930s to channel storm runoff and prevent flooding, the tunnel beneath Nogales has been used for decades by smugglers as an avenue into the United States.
In recent years, the Border Patrol has erected two sets of heavy steel doors, designed to open when the tunnel fills with water, to make it more difficult to cross through the tunnel. There are also cameras and sensors to alert the Border Patrol when somebody is trying to cross.
The monsoon rains usually cause damage to the gates or cameras and sensors, making it easier for illegal immigrants daring enough to enter the tunnel during the rainy season. But on July 12, when heavy rains fell in the border region, the new concrete barrier served as a bottleneck, causing the water to fill up on the Mexican side of the channel and pressure the aging structure, Quintanar said.
“We can affirm, with scientific and technical data, that it obstructed the flow of water,” said Quintanar. “It diminished the hydraulic capacity of the wash and caused the upper slabs of the wash to break, along with the pavement on Calle Elias, and the water flooded out.”
A concrete aboveground border wall east of the wash further escalated the damage by stopping the water that spilled onto Calle Internacional and Calle Elias from flowing into the United States. The barrier in the wash, however, was the catalyst for the flood, he said.
The $8 million in damage caused by the flood includes damage to 578 homes and 45 cars, Mexican officials say. State officials have declared the damaged part of the city a disaster zone.
Two days after the flooding, U.S. officials found the bodies of two people in the wash. They suspect they were illegal immigrants trying to get through the tunnel the evening of the flooding.
Removing some of the barrier might help slightly but is not enough to prevent future flooding in heavy rains, said Quintanar and Martínez Dabdoub.
“Until the wall is completely demolished, it will continue to be a concern for both countries,” said Quintanar.
Martínez Dabdoub said he’s also evaluating a way for Nogales, Sonora, to get some re- imbursement for property damage from the United States since the barrier appears to have caused the flood.