Over the past few days, Harvey has dumped between 27 and 35 inches of rain over Harris County, with multiple stormwater gages registering seven-day readings of more than 40 inches in some parts of the county, according to the Harris County Flood Control District.
The downpour from Harvey unleashed about 9 trillion gallons of water before it was over, an onslaught that left Addicks and Barker, the pair of dams that have protected downtown Houston from extinction-level flooding for more than 70 years, filled above capacity and overflowing for the first time in history, as we've noted.
While the U.S. Army Corps of Engineers has maintained throughout the storm that Addicks and Barker are structurally sound, the Corps also got permission to start releasing water from both reservoirs before the rain had even stopped, another first. Initially, the controlled release, which was slated to increase to about 4,000 cubic feet per second, failed to work. The controlled release from Addicks and Barker started late Sunday night, but the reservoir levels were still rising. On top of that, water was already spilling over the sides of Addicks in an "uncontrolled release" and Barker was expected to soon follow suit, as we reported.
This trend continued into Tuesday, and projections from both the Corps and Flood Control called for the water levels in Addicks to clear 110 feet and for those in Barker to rise above its 108-foot capacity.
And then it happened.
The rain began to ease off and then it stopped, and by evening the sun came out. Even better, the water levels in both Buffalo Bayou and the Houston Ship Channel began to drain faster than anticipated. This prompted the Corps to double the amount of water both dams will be releasing. When the controlled releases are up to maximum flow, the reservoirs will be letting out about 8,000 cubic feet per second, for a grand total of about 16,000 cubic feet per second. So far, the reservoirs are only putting out about 13,800 cubic feet per second.
Still, it's not over yet and the increase of water from Addicks and Barker is showing up in neighborhoods near the dams and along Buffalo Bayou. Roads running through the reservoirs are also underwater and are expected to remain submerged for weeks to come. And considering there's still runoff streaming down from the sections of Harris County and other counties above the reservoirs, the pool levels at both Barker and Addicks may continue to rise, even though the reservoir outlet gates are open.
"If water is not in your house in these areas behind us, it will probably not be in your house," Flood Control District meteorologist Jeff Lindner said during a press conference Wednesday outside of Addicks (next to the section where the uncontrolled release of water is spilling over the dam). But his words of comfort only took it so far.
When asked whether more structures along Buffalo Bayou would flood, a representative from the Corps dodged the question, but then Lindner stepped up and answered it. "As this flow moves south toward Buffalo Bayou, additional structures could flood as it comes down along the east side of the dam and the west side of town," he said.
About 3,000 homes near Addicks have water in them and the homes closest to the reservoir can expect to have water in them for several weeks. Right now, the releases are ongoing and the stretch of Buffalo Bayou from the dam to down Dairy Ashford is stable, Lindner said. However, from Dairy Ashford to Piney Point the bayou is expected to continue to rise.
Meanwhile, forks of the San Jacinto River, Cypress Creek, Spring Creek and a slew of other bayous and creeks in the area are still slipping over their banks.
Or, to put it another way, the rain may be over, but the flooding decidedly is not.