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Monsoon storm floods border wall project across Arizona's San Pedro River

Monsoon storm floods border wall project across Arizona's San Pedro River

A monsoon storm Saturday night sent a flood down the San Pedro River that smashed through the construction site for the border wall project in the river bed.

The storm caused the river to swell to about 10 feet deep around midnight on Saturday night, the largest flood so far this monsoon season on the river that runs through southern Cochise County. The area where the river crosses the U.S.-Mexico border showed obvious signs of damage on Monday, including a jagged gash through a dirt road contractors built across the deepest section of the river bed and concrete foundations buried in mud.

Contractors started laying the foundation for the wall a month ago, over the objections of advocates for the river who warned officials that they were “rolling the dice” in the hopes that monsoon floods wouldn’t destroy the project.

When the storm hit on Saturday night, contractors had installed much of the concrete foundation for 30-foot-tall steel bollards and built a dirt road across the river, but they had not yet started installing the bollards.

The project includes building a wall of bollards filled with concrete across the river about 10 feet north of the international boundary. The bollards are 6 inches wide and separated by 4 inches of space. A series of swing gates designed to allow water to flow unimpeded during heavy rains will be installed under the wall. A vehicle bridge will be built north of the wall.

The National Weather Service issued a flood advisory for the area on Saturday and a U.S. Geological Survey gauge about 5 miles north of the border in Palominas showed the water level in the river rose to about 10 feet deep at 12:45 a.m.

A July 8 photo shows the concrete footers being constructed. The area was hit by a storm that caused the San Pedro River to swell to 10 feet Saturday.

The entire width of the river bed, some 500 feet, showed signs of flooding. Much of the concrete foundation was buried in mud or was in the process of being dug out of the mud. Metal casing wrapped around sections of concrete foundation high up on the river bank was twisted and riddled with debris from the flood.

Evidence of the force of the flood also could be seen outside the construction area. Debris was caught in the green branches of a tree that had toppled over a few dozen yards north of the construction site. Smaller plants on the river banks were still plastered against the ground.

The damage caused by the storm was not "significant," according to Matthew Dyman, a spokesman with Customs and Border Protection. No construction workers were injured and work has continued with limited interruptions.

With regard to the future of the project across the San Pedro River, "further construction of the bridge and the above ground portion of the barrier will be dependent on the amount of water flow in the river," Dyman said.

Crews with Southwest Valley Constructors, a New Mexico-based affiliate of construction giant Kiewit, had moved out of the river bed on Monday and were working on the wall to the west of the river. 

Monsoon construction

Advocates warned of monsoon floods as soon as the wall project was announced last summer.

“The contractors have been pretty lucky that it’s been a flyweight monsoon so far,” said Myles Traphagen, borderlands program coordinator for the Wildlands Network in Tucson and science coordinator for the Malpai Borderlands Group.

Similar wall projects across three major streams in the San Bernardino Valley, which includes 24 miles of the border from Douglas to the New Mexico state line, are seeing similar flood issues, he said.

“In the rush to ‘build, baby, build,’ there has been no forethought on how to deal with the challenges these walls present to water flow,” Traphagen said. 

Exposed, damaged rebar and remains of concrete footers show in the San Pedro River after a monsoon storm runoff damaged the border wall work site on Saturday August 1 near Hereford, Ariz. Mexico is at left.

Officials with the Army Corps of Engineers did not respond to an inquiry from the Star about the flood damage on the San Pedro River.

In early July, the Star asked Corps officials about the risks of starting construction in a river bed at the beginning of monsoon season.

In terms of the potential for damage from the monsoons, “critical components of the fence and the bridge structures that needed to be constructed in dry conditions have been completed,” Corps spokesman Jay Field said in July.

“Work on the remaining components is not expected to be significantly impacted by potential rain,” Field said.

When asked about the potential cost to taxpayers, Field did not address the specific contract that includes the San Pedro River wall, but said “generally, a contractor’s liability insurance covers damages.”

A monsoon storm on Aug. 1st near Hereford, Ariz. washed out trenches across the San Pedro River that were the foundation for a new U.S./Mexico border wall.

Wall damage elsewhere

Damage to border wall construction erupted into public view last week when a video went viral on social media showing high winds blowing down sections of the wall.

The person who posted the video said, inaccurately, that the damage was caused by Hurricane Hanna, according to CBP officials. The incident likely occurred during a wind storm in June in New Mexico.

So far, high winds have knocked down three sections of wall that were not fully anchored into place, according to the Corps. The first incident occurred in Calexico, California, on Jan. 29, followed by one near El Paso on April 22, and a third, also near El Paso, on June 5.

“In each case the contractor revised its panel-bracing strategies and construction has continued without further incident,” according to Raini W. Brunson, a spokesperson for the Corps.

“Our contractors plan for these types of contingencies to include the associated costs and repairs for any damages; additional taxpayer dollars are not used, Brunson said.

There were no injuries associated with these incidents, Brunson said.

UPDATE: This story was updated Aug. 5 with comments from Customs and Border Protection.

Contact reporter Curt Prendergast at 573-4224 or

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