The Addicks Reservoir, located about 19 miles west of downtown, spilled over for the first time in history Tuesday morning and both it and the Barker Reservoir are at record levels as the Houston area continues to be spattered with more rain from Tropical Storm Harvey.
Jeff Lindner, a meteorologist with Harris County Flood Control District, explained at a press conference on Tuesday morning that neither Flood Control nor the U.S. Army Corps of Engineers knows what to expect from this situation, because it is uncharted territory.
“This is something we’ve never faced before so we are trying our best to wrap our hands around what exactly this water is going to do as it interacts with subdivisions, roadside ditches, underground drainage systems that it’s all going to be interacting with as it moves east toward the Beltway,” Lindner said.
Edmond Russo, with the Army Corps of Engineers, explained that the uncontrolled releases (which is a nice way of describing water over which the Corps has no control) have begun to slop over the spillways at Addicks and Barker and the water levels have extended past the government property around the sites of these reservoirs.
The Corps, the entity that owns and operates Addicks and Barker, started releasing water from the dams late Sunday night because the dams, built in the 1940s and designed to hold water until there can be a controlled release, were under enormous pressure, having taken in more water than ever before because of Hurricane Harvey.
As we’ve previously noted, Addicks and Barker were classified as two of the most dangerous dams in the United States as of 2009, and while the Corps has done some repairs since then, issues about the soundness of the structures have remained, which is part of why the Corps went ahead and started releasing water, something it has never ordered during an ongoing rain event since the reservoirs were first constructed more than 70 years ago.
It had been looking increasingly likely that Harvey’s continuous onslaught of rain would cause the dams to begin to spill over in an “uncontrolled” fashion since the controlled releases from the reservoirs had failed to stop the pool levels at Addicks and Barker from continuing to rise as of Monday night.
Still, not even the officials at Flood Control and the Corps saw this coming, Lindner acknowledged. “When we first started talking about this, we weren’t sure we would be seeing this situation, and now we are certain we will be seeing water in these areas.”
Addicks rose to 110 feet by Tuesday morning, topping over its 108-foot barrier and causing water to spill out 34 feet onto non-government land. Lindner listed the main neighborhoods affected by the spill so far, including Twin Lakes, Eldridge Park, Lakes on Eldridge North, Independence Heights and Heritage Business Park. Barker is also up to its 104-foot barrier.
“The biggest challenge we face right now is to determine how the flow interacts with the system, and how the water will go as it comes out of the spillway,” he said.
The flow of the waters going into the neighborhoods is going to increase as the levels of the reservoir continue to rise, and at this point the levels at both Barker and Addicks have risen so high the flood gauges have flooded, and Lindner encouraged people in those areas to leave sooner rather than later since once their streets flood, they won’t be able to get out without help.
“This is not going to happen fast,” Lindner said. “This is a slow rise.”
Harris County Flood Control is keeping a list of the neighborhoods it is predicting will see water from Addicks and Barker as both controlled and uncontrolled releases continue to move slowly out of the reservoirs, into those surrounding neighborhoods and then into Buffalo Bayou.
Lindner said right now – and that’s a key phrase, because while both Flood Control and the Corps are working furiously to model these conditions and figure out how this is going to play out before it actually happens – they believe water will move toward Sam Houston Tollway, head south to I-10 and eventually into Buffalo Bayou.
About 5 percent of the water in the bayou will be from the controlled release, 15 percent will come from the uncontrolled release and the rest will come from the runoff and rain downstream of the dams. Buffalo Bayou’s water levels will not be receding anytime soon, and even after Harvey is finally over, the controlled releases for the dams will continue for anywhere from one to three months.
While Lindner and the other officials working this currently believe Houston itself will not be much affected by the releases from Addicks and Barker, he admitted they don’t actually know what specifically is going to happen. He pointed out that he can’t think of any other city that has faced this particular problem, with overflowing reservoirs and neighborhoods built right up against the structures.
“At first we thought there wouldn’t be any water in these areas, and then we realized there would. Then we thought the water would only be in the streets, but now we know it may be in the structures as well,” Lindner said. “This is uncharted territory.”