HOUSTON — This city has struggled for years to control routine flooding as stormwater managers waged a losing battle against developers.
But experts see signs the tide may be turning, even as the city copes with a flooding disaster in what’s been a monster wet month here.
Extreme thunderstorms that rolled through on Memorial Day evening trailing weeks of relentless rain have called attention to a network of drainage canals and two major federal flood control projects. If just one of those 70-year-old dams fails, experts say, the flood would likely eclipse damage done to New Orleans by Hurricane Katrina in 2004 given Houston’s much larger population.
Mayor Annise Parker acknowledged in a press conference yesterday that flooding in some areas is chronic — the result of relentless development paving over wetlands that would have soaked up stormwater. "We had localized street flooding, sheet flooding in certain areas, and the underpasses, the places in Houston that often flood in a very severe rain flooded," she said.
But the U.S. Army Corps of Engineers and the Harris County Flood Control District (HCFCD) say they are starting to get ahead of sprawling development that has overwhelmed the region’s natural defense against floods.
"We see the difference with each passing year, with each project we complete," HCFCD spokeswoman Kimberly Jackson said.
Work over the past two years to shore up the Addicks and Barker dams has held up in the face of this month’s deluge, officials said. Army Corps natural resources manager Richard Long said his team is preparing for three to four years of more construction on both dams. Once completed, he said, the structures should protect Houston for another 70 years.
The corps rates the condition of both dams as "extremely high risk." Collapse isn’t imminent, but they are in desperate need of a more permanent construction solution, the agency said.
"If we had a major dam failure here, it would be devastating to the city of Houston just because of the location of the dams," Long said. "There is a potential for failure — there is no perfect dam — and due to the age of our dams and the type of construction used on the dams 70 years ago, the potential for failure is higher."
More than $2 million was spent on temporary repairs to the dams — earthen berms that front mostly dry land until rains come. Millions more will be necessary to put in place a permanent fix. Work on that will begin later this year.
In spite of a month of rain and the torrential downpour that brought as much as 11 inches of overnight precipitation Monday to parts of the city, the reservoirs behind the Addicks and Barker dams still have room for more, Long said. Addicks Reservoir was estimated to be about a quarter full, with the Barker Reservoir encompassing much of George Bush Park about a third full. No water was being released to give the city’s main waterway, Buffalo Bayou, time to drain itself.
Meanwhile, HCFCD’s Jackson said her agency is making progress in putting flood mitigation projects in ahead of shopping malls and housing developments sprawling in the city’s western reaches. And the district is busy returning to the city’s urban core to undo damage done by previous growth spurts by creating more green space to sponge up overflowing waterways.
The district is in the midst of a study on how to rehabilitate Brays Bayou, a major drainage way that has helped mitigate the current disaster.
"There were significantly fewer homes that were impacted than would have been, say, prior to those components of the projects that we put in place," Jackson said. "When you see those types of examples, you feel that it’s really making a difference."
The Harris County Flood Control District, formed after floods devastated Houston in 1929 and 1935, builds water retention ponds designed to look like parks and is working to expand open space and improve the watersheds of creeks that run into the larger bayous.
To date, the district has bought out about 3,000 people who had property in flood plains, razing their houses and converting them to open areas that can soak up excess water during floods.
But what the district can’t do is tell the city how to build. The city’s streets and freeways are paved with impermeable concrete that pool water and increase hydroplaning risks for drivers. The effect is most notable on a short concrete stretch of Sam Houston Parkway in the northwest, where a blinding spray and slippery conditions during even modest rains contrast sharply to a less wet road surface on parts of the parkway that are paved with asphalt.
"We will construct those regional detention basins, but we don’t have any oversight into what is built and what Harris County permits," Jackson said.
But "low-impact development techniques" are gaining a foothold in Houston’s fastest-growing neighborhoods, she said. Developers are also beginning to reach out to her agency before planning a project, she said, driven in part by demand for communities tired of seeing an endless parade of parking lots and big-box retailers smothering open spaces.
The most urgent task facing the city is getting its two main flood control projects completed before the end of the decade. Army Corps officials stress that there is no immediate risk of a catastrophic failure. But the work can’t wait any longer. Houston’s population keeps rising rapidly, increasing the stakes each year.
"We do not want to downplay the need for these repairs that we’re going to do," Long said.
Following Monday’s flood, the mayor’s office launched Level 1 emergency response measures. The last time that occurred was in 2008 following Hurricane Ike. Only this time it wasn’t an epic hurricane that caused problems, just lots of rain.
The office is reporting five storm-related deaths and two missing people. The city government estimates that about 1,400 structures were damaged in the flooding. Thousands of cars were abandoned in the rising flood waters. About 100,000 gallons of untreated sewage spilled when a water treatment facility overflowed (see related story).
Rains fell again this morning, and more is forecast. The Memorial Day weekend storms caused severe damage to central Texas, and the recurring rain has covered almost the entire state, from the Gulf of Mexico coast to the panhandle region of Amarillo.
Parker requested disaster relief from Texas Gov. Greg Abbott. During a press conference, Parker said Abbott politely told Houston it would have to get in line.
"He’s hearing this from cities across central Texas," she said.