Two of America’s Most Dangerous Dams Are Barely Protecting Houston From Harvey

Water in two reservoirs is at record heights, and officials have to purposely flood areas downstream to relieve the pressure. One expert said he’s sounded the alarm for years.


HOUSTON—In the 1940s, the Army Corps of Engineers built two massive dams to the west of Houston to hold back the torrential rains that regularly inundate the city. When the weather is dry, the drainage areas upstream from the two dams are grassy parks where local residents ride bikes and take their dogs for walks. But when it rains they fill up, creating the Barker and Addicks Reservoirs, which have a combined storage capacity of 411,500 acre-feet of water.

For nearly 70 years, the Barker Dam and Addicks Dam have done their jobs, keeping floodwaters from wiping downtown Houston off the map and allowing development along Buffalo Bayou, the city’s main waterway. But Tropical Storm Harvey is testing the dams like never before.

On Tuesday morning both Addicks and Barker Reservoirs overtopped their banks for the first time in history, backing up thousands of cubic feet per second of water into the neighborhoods north and west of the reservoirs and flooding thousands of homes with up to five feet of water.

What's worse is if the dams somehow fail.

“That would dwarf anything that has happened so far,” said Jim Blackburn, a professor in the civil and environmental engineering department at Rice University. “The Army Corps of Engineers is very hesitant to release their maps of what that would look like, because it would be absolutely devastating.”

Blackburn said if the dams burst, Houston’s two biggest bayous, Buffalo and Brays, might become a single miles-wide river.

According to the Corps, the two dams are among the six most dangerous in the country, largely because of the potential devastation that would occur should they fail.

“It’s a very low-risk event,” Blackburn said. “But the Corps wouldn’t have put them in the top six most dangerous dams if there wasn’t at least a chance of it happening.”

Officials from the Corps and the Harris County Flood Control District said they were monitoring the dams’ structural integrity and have seen no problems so far. They said a construction crew is on hand to perform any repairs if they become necessary.

To mitigate the flooding and relieve pressure on the dams, the Corps continues to release water from the two dams into Buffalo Bayou at a rate that will reach 4,000 cubic-feet per second. This release is not expected to increase the level of the already flooded bayou because downstream rains have abated, according to the Harris County Flood Control District.

North and west of the dams, though, water is expected to continue rising until Thursday despite the planned releases.

Just last month, Vinod Hopson and his wife moved into a house on a cul-de-sac in the Glencairn neighborhood north of the Addicks Reservoir.

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“We did a lot of research before buying,” Hopson told The Daily Beast on Tuesday. “I knew the Memorial Day flood in 2015 had flooded Highway 6 [to the east], but everyone said this area had never flooded.”

Now, water from the overflowing from the Addicks Reservoir is about a quarter mile south of his house and still rising. The rain gauge in Hopson’s backyard has measured 37.25 inches of rain since Friday.

“We’re worried about the reservoir backing up,” he said. “We’re wet, we’re anxious.”

One of the people in the flood’s potential path is Janice Smaihall, who lives in the upscale Barker’s Landing subdivision east (downstream) of the Barker Dam. Several of her neighbors are staying with her because they lost power. And while their subdivision hasn’t yet flooded, another one across Memorial Drive has.

“You’d be an idiot if you weren’t concerned a bit,” Smaihall said. “I have everything ready to go in waterproof bags with all the essentials if we have to go. The main reason we’re hanging tight is, where do you go?”

Blackburn, the Rice professor, said he’s been trying to warn Houstonians about the two dams for years.

“None of the officials wanted to talk about it—it’s like they’re intentionally trying to suppress the information,” he said.

One of the reasons for inaction, Blackburn believes, is widespread denial of climate change in the city and state. The longtime director of the Harris County Flood Control District, Mike Talbott, has dismissed concerns about climate change as part of an “anti-development agenda.” Talbott retired last year, but his successor, Russ Poppe, also rejects the idea that climate change is having an effect.

“Our officials are going to have to get used to hearing things they don’t want to hear,” Blackburn said. “Our engineering is based on old statistics that don’t take climate change into account. We spend all our time in this part of the world denying climate change, but that keeps us from asking the important questions. I think this event has opened up that issue.”