HOUSTON (CN) - Two giant dams upstream from Houston are at "extremely high risk," but repairs should keep the city safe from catastrophic flooding, the Army Corps of Engineers told Houstonians this week.
Addicks and Barker Dams straddle Interstate 10, 20 miles upstream from downtown Houston. The Corps of Engineers built them in the 1940s to hold back Buffalo Bayou after it flooded the city in 1935 and caused more than $2 million in property damage.
Despite that history, many Houstonians knew nothing about the dams even after an FOIA request by the Sierra Club brought to light a memo the Corps of Engineers circulated internally in July 2010 that stated the dams "currently face significant risks of 'catastrophic failure,'" and the memo's implications seeped out through the press.
The earthen dam embankments are massive - Barker spans more than 13 miles and Addicks a little over 11 miles. The two reservoirs can store up to 410,000 acre feet of water: enough water to cover 410,000 acres a foot deep.
Water is seeping under gates that control the flow from the reservoirs, and undermining the dams' integrity, the Corps' onsite manager Richard Long told Houston's NPR affiliate in late February.
But the Corps of Engineers is not sitting around, hoping the worst won't happen. It awarded a $71 million contract to Granite Construction Co., a California firm, to decommission the gates and replace them with steel-lined conduits. The project, announced in August 2015, is under way and is supposed to be finished in 2019.
Long and Col. Richard Pannell, head of the Corps' Galveston Division, backtracked from the doomsday warnings at a meeting Wednesday in a community center.
"There was some misinformation that got put out," Long told two dozen residents who braved heavy rain and traffic, and the inevitable danger of flooded streets when Houston is hit with a deluge.
Long was responding to the fears of a woman who said she'd heard the dams could not be filled to capacity because of the danger they could collapse.
"At no time were we at a situation where we weren't able to use the full capacity of the reservoir," Long said. "There was a time when we were concerned about using that full capacity," Long hedged, speaking from his seat on a dais, his Southern drawl amplified by a microphone in the musty meeting room.
The two dams are among six U.S. dams the Corps of Engineers has categorized as " extremely high risk " to move them to the front line for federal funding for repairs.
"It is important to know that Addicks and Barker dams are not in imminent danger of failing," the Corps of Engineers said in a statement .
"These two dams form reservoirs that are dry much of the time. They are continuously monitored by a full-time staff to ensure their structural integrity."
Should they fail, they could cause $60 billion in damage to downtown Houston, the refinery-lined Houston Ship Channel and the 21 hospitals and 54 research institutions in the Texas Medical Center, the Corps of Engineers said, so it isn't taking any chances.
"The fact that the Houston metropolitan area is the nation's fourth-largest population center is a primary concern. Any dam safety issues at Addicks and Barker could have a far greater impact due to the magnitude of people and property downstream, as opposed to other dams around the country in rural or low-population density areas," the agency said.
Long said the Corps closes the dam gates before predicted rainfall, then releases the water into Buffalo Bayou at a normal rate of 2,000 cubic feet per second (cfs).
In late May 2015, a thunderstorm dropped enough rain in Harris County to fill the Astrodome more than 500 times, flooding 4,000 homes , and the Corps' Galveston District got permission from its Dallas headquarters to increase the flow from the dams to 3,000 cfs, Long said.
Houston is the Harris County seat.
"The May event caused an extremely high pool elevation and as we were approaching these higher pool elevations we hadn't seen how the dam would perform above the pool-of-record, so it did concern us some. So we requested permission to go up to 3,000. It was a onetime granted permission," Long told residents who were concerned the higher flow rate could become more common and cause more downstream flooding.
The pitter-patter of rain on the roof, thunderclaps and the room's poor lighting, which cast the six panelists in shadow, gave the meeting an ominous feel in line with the talk of watery apocalypse.
"Are we going to be able to get out of here?" joked audience member Susan Chadwick, a trustee of nonprofit Safe Buffalo Bayou, which advocates preserving the bayou in as natural a state as possible.
"The answer is yes. If you have any problems I've got a truck and you can jump in the back," Pannell said.
Panelist Steve Fitzgerald, a chief engineer with the Harris County Flood Control District, did not inspire confidence. He held up a tablet, red blotches visible on its screen.
"Well, it's getting worse. I'm the flood watch leader for Harris County and we're activated right now so I've been watching the radar the whole time. There's more coming now," he said.
"So should we leave?" someone asked. The meeting ended.Follow @cam_langford
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