Houston-area dam overflows, levee leaks
HOUSTON — After days of record rainfall from Harvey, a 70-year-old dam overflowed and a levee leaked Tuesday, sending water coursing into nearby neighborhoods in Houston and a southwestern suburb.
Despite controlled releases by the U.S. Army Corps of Engineers, the water level of Addicks Reservoir in northwest Houston rose past the dam’s gates for the first time in its history, rising more than 10 inches past the spillway. The neighboring Barker Reservoir also was at risk of overflow.
In Brazoria County, in the southwestern corner of greater Houston, rainwater began to ooze through a levee and into the Columbia Lakes subdivision, prompting county officials on Twitter to warn residents to “Get out now!!”
The levee, which is maintained by the subdivision, was “temporarily patched” several hours later, said County Judge Matt Sebesta, the county’s top government official. “We’re hoping that it will hold. But water will still be very high in that area, so there is a chance it will come over the top of the levy.”
More than 100 subdivisions in the region are under voluntary evacuation orders because of flooding, and the number is expected to rise.
On Monday, the corps began releasing water from the Barker and Addicks facilities into the Buffalo Bayou in an effort to prevent erosion at the base of the dams. Combined, the two reservoirs were releasing 8,000 cubic feet per second Tuesday.
Despite the releases, the water level at Barker Reservoir was rising faster than expected. Both reservoirs’ gauges flooded Monday night, preventing predictions of when overflows might occur, said Jeff Lindner, Harris County’s flood-control meteorologist.
Before the corps released the water, Col. Lars Zetterstrom, Galveston District commander, defended the action in a statement: “If we don’t begin releasing now, the volume of uncontrolled water around the dams will be higher and have a greater impact on the surrounding communities.”
Some subdivisions would see flooding, Zetterstrom said, but Addicks and Barker should continue to perform “as designed,” preventing the flooding of downtown Houston.
The Addicks and Barker dams were considered among the world’s longest when they were conceived after disastrous floods in 1929 and 1935. When built, they occupied vacant fields far from the city center. But Houston’s sprawl has long since enveloped them.
The reservoirs were designed mainly for water storage, not flood control. They are dry about 90 percent of the time and are designed to send runoff and rainwater coursing into the Buffalo Bayou — away from downtown Houston and the Houston Ship Channel.
Number of people rescued by Houston police
Estimates on number of people displaced
Inches of rain from Harvey at Cedar Bayou, Texas, a new continental U.S. record
Inches: record rainfall for a year (2011) in Columbus
Amount of Harris County that's under water, about the size of Franklin County
Number evacuated from flooded neighborhoods in southwest Louisiana