As Harvey has continued to slop water onto the Houston area, the U.S. Army Corps of Engineers started releasing water from Addicks and Barker reservoirs on Sunday, as we've reported.
Constructed in the 1940s to prevent a massive flood from ever overtaking downtown Houston (this was done in the wake of the devastating 1935 flood), the dams were dubbed to be at "extremely high risk of catastrophic failure" in 2009, but have not had much in the way of upgrades in the years since then. Because of this, they can hold only so much water safely.
So on Monday morning, Houston Mayor Sylvester Turner dug into why water needs to be released from Addicks and Barker, sort of.
Turner announced the Corps has started out by releasing about 2,500 cubic feet per second from Addicks and about 2,000 cubic feet per second from Barker, adding up to about 5,000 cubic feet per second that is now coming down Buffalo Bayou. The plan is to increase the release level to about 8,000 cubic feet per second from both reservoirs, according to Turner.
"When that water is released, it is going to come downstream. It is going to add water to Buffalo Bayou," Turner said. "They are releasing the water and it is gradual, and they are indicating that if they don't do it, the water builds up and it will go around the dams and be exponentially worse."
So what happens to the water being released? Well, it flows into Buffalo Bayou, spreading out into the neighborhoods near Addicks and Barker, spreading out into the homes near Addicks and Barker and gradually increasing the levels of Buffalo Bayou as the water flows down into the city.
It will not flood Katy, according to Harris County Flood Control District. Instead, the water will move into neighborhoods like Bear Creek Village, which is located right next to Addicks. Authorities expect about a thousand homes to flood because of these gradual releases.
From there the water probably will not subside quickly. It could be anywhere from weeks to months before the water recedes and people are able to get back into their homes, which is why officials are encouraging people in these neighborhoods to leave now, if they can.
That's bad enough, but the releases, which will take about 12 hours to reach downtown Houston under current flow conditions, also mean Buffalo Bayou will not be receding much anytime soon, Turner stated.
And the thing is, the releases have to happen because the other option – to let the dams continue to hold water without any relief – is untenable since there is always a chance that these dam systems will ultimately not be able to handle the water that's coming in.
“If they don’t do it, if they don’t release the water and it goes up and then it goes around Addicks and Barker, that will be incrementally worse,” Turner said, describing a much gentler worst-case scenario that completely avoids even hinting there’s a chance the dams could collapse entirely.
Talking to the Houston Press, environmental lawyer Jim Blackburn was more direct about the reasons for releasing the water. “The dams could burst," Blackburn said. "That’s the scenario that is causing the Corps to do these releases. I’ve been trying to talk about the risk of this for years now. I’ve litigated it. But frankly, we as a community just didn’t want to talk about what we knew could happen.”
Blackburn acknowledges that the chances of a full collapse actually occurring are relatively low, but notes that they should not be disregarded.
“The risk of actual structure failure may be relatively low, but the consequences are so high that it is a definite risk or there would not be this policy. There is some underlying structural concern that is underlying the Corps decision-making,” Blackburn, who has been trying to draw more public attention to concerns over Addicks and Barker for years now, says. ”They’re not going to say this, but it is better to flood houses than to kill people, and those are the two bad choices the Corps is looking at.”
Even with the controlled releases that the U.S. Army Corps of Engineers started on Sunday, the reservoirs are still taking in more water than they are putting out. But the other option risks the dams collapsing in part or even, in a nightmare scenario, entirely.
Not that Turner said this during the press conference, of course. He was more diplomatic, emphasizing the unknown and how changeable everything is right now. "This is a very dynamic situation and things could change hour by hour and day by day," Turner said.
Houston Flood Czar Steve Costello then stepped up to the podium, explaining that the issue is they are getting a lot of water upstream of the dams and are concerned about the amount of water in the dams.
"If we get more rain downstream or if they get more water upstream, that's probably going to change, but we're not anticipating any increase in flooding on Buffalo Bayou," Costello said. "If you live next to a major stream between I-10 and Westheimer, that's Buffalo Bayou. Those are the neighborhoods that are going to be challenged over the next couple of days."
And the thing is, the releases have to happen because the other option – to let the dam continue to hold water without any relief – is untenable since there is always a chance that these dam systems will ultimately not be able to handle the water that is coming in. Even with the controlled releases that the U.S. Army Corps of Engineers started on Sunday, the reservoirs are still taking in more water than they are releasing. But the other option risks the dams collapsing in part or even, in a nightmare scenario, entirely.