A 40-foot stretch of mesh border fence east of Lukeville in Southwestern Arizona was knocked over Sunday by rainwater rushing through a wash.
This is the first time any part of this 5.2-mile stretch of fence has been knocked down by floodwaters since it was built in 2007-2008, but it is the latest in a series of challenges for the barrier during rainstorms, said Organ Pipe Cactus National Monument Superintendent Lee Baiza.
The design does not allow for the free flow of water in natural washes intersecting the border, he said. In washes, the fence has grate openings at the bottom that are 6 inches high and 24 inches wide with 1-by-3-inch bars.
"The fence acts as a dam and forms a gradual waterfall," Baiza said. "It starts to pile up on the bottom as the grass, the leaves, the limbs start plugging up. The water starts backing up and going higher. The higher it gets, the more force it has behind it."
Sunday's storm dumped 1.5 to 2.5 inches of rain in the area upslope from the area where the fence failed, according to the National Weather Service.
Bursts of strong rain are common at the park, meaning that other parts of the fence that are in the natural washes could be at risk of being knocked over, too, Baiza said.
The problems were anticipated by Organ Pipe officials.
In October 2007, before the fence was built by Kiewit Western Co. for $21.3 million, Organ Pipe officials told the U.S. Department of Homeland Security they were worried that the design would impede the movement of floodwater across the border; that debris would get trapped in the fence; that water would pool; and that the lateral flow of water would cause damage to the environment and patrol roads, according to a report issued by Organ Pipe in August 2008 about flooding that summer.
In response, the Border Patrol issued a final environmental assessment with a finding of no significant impact. It also said the fence would not impede the natural flow of water or cause flooding.
The agency said it would remove debris from the fence within the washes immediately after rains to ensure that no flooding occurred.
At a December 2007 meeting, Kiewit officials stated in a handout that the fence design "would permit water and debris to flow freely and not allow ponding of water on either side of the border" because the drainage crossing grates "met hydraulic modeling requirements."
"Now we know who's right," said Matt Clark, Southwest representative for Defenders of Wildlife. "Period. End of story."
The situation is an example of how Homeland Security ignored expert advice from people within the federal government to ram through border-fencing projects, Clark said.
The first sign of problems occurred on July 12, 2008, when the 15-foot-high wire-mesh fence halted the natural flow of floodwater during a storm that dumped 1 to 2 inches of rain in 90 minutes around the border towns of Lukeville, and Sonoyta, Sonora.
Water pooled behind the fence and flooded into the Lukeville Port of Entry and private businesses, causing damage.
At the Gringo Pass convenience store, merchandise was damaged and the store was closed for cleanup, according to a lawsuit filed by the company against the U.S. government in 2009. The lawsuit says the flooding diminished property value by $6 million.
On Sunday, the storm also caused flooding in several buildings in Lukeville owned by Gringo Pass, Inc. after water pooled against the border fence and seeped into the structures. Those buildings now include a restaurant, post office, shuttle company and a duty-free store that had just received a new shipment of goods, said a store spokesperson. The convenience store is now out of business.
After the July 2008 flooding, Organ Pipe Cactus National Monument officials issued a 17-page report detailing how it happened. Baiza said then he wanted government officials to revisit the design to prevent future problems.
To remedy the problem, the Army Corps of Engineers installed 50 to 60 liftable gates in 11 drainage systems as part of a 2010 drainage-improvement project. The system calls for the gates to be raised by a hoisting apparatus during storms so water can freely flow.
On Sunday, though, the gates were down, Baiza said.
Questions about the fence, the design and gates were not answered Tuesday by the Department of Homeland Security or the Army Corps of Engineers.
The recent events show that there should be no border barriers in water crossings, Clark said. Officials should use alternative security measures such as ground sensors in those areas, which would not only allow floodwater to move freely but also create breaks for wildlife.
"Flooding is a very visual and physical reminder that walls block ecosystem processes," Clark said. "There are major costs both fiscally and environmentally to building walls across watersheds."
Contact reporter Brady McCombs at 573-4213 or firstname.lastname@example.org