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Four lakes formed by dams on the Guadalupe River east of San Antonio are set to be drained in September after the failure of a similar dam in May caused safety concerns up- and down-river.
Starting Sept. 16, Lake Gonzales, Meadow Lake, Lake Placid, and Lake McQueeney are all to be drained, or “dewatered,” in the language of the Guadalupe-Blanco River Authority, the government entity that manages them.
GBRA officials say the dewatering is necessary for lakes held back by the roughly 90-year-old dams, whose conditions constitute a safety risk. The GBRA once maintained six reservoirs on the main stem of the Guadalupe River. After the failure of the dam at Lake Wood in 2016 and loss of the dam at Lake Dunlap in May, only four are left.
“I got one word for it in the last three months: It’s been devastating,” said J Harmon, president of the Preserve Lake Dunlap Association, who has lived near the lake for 15 years.
The dam failure at Lake Dunlap led to the lake emptying in a matter of days as water flowed out of a broken spillgate. Charlie Hickman, the GBRA’s executive manager of engineering, said the authority hired divers and engineers to help inspect the broken gate and those still functioning at the dam. They found that the steel hinge at the base of the gate was deteriorating, he said.
“The level of deterioration was really significant,” Hickman said. “That led to our engineers making a recommendation that you could not continue to keep these gates in service.”
The position of those hinges made it impossible for the GBRA to inspect or repair the hinges that haven’t yet failed, he said. With modern dams, it’s often possible to dewater only a small section of the lake near the dam to do inspections, but not with those on the Guadalupe River.
“Our dams do not have that type of system,” Hickman said. “It just wasn’t a consideration at the time they were built.”
Harmon said on Thursday he saw first-hand the degraded hinge that the GBRA pulled out of the Lake Dunlap spillgate.
“After I viewed that, I called my friends down on the other lakes and told them, ‘Absolutely do not get close to those dams,’” he said. “I hope they last another 30 days before they can do an inspection on them.”
Now, property owners and others who depend on the four remaining lakes are soon to join those surrounding Lake Dunlap. This month, the GBRA sent 1,454 certified letters to lakeside residents advising them to prepare for water levels to begin dropping on Sept. 16.
The dewatering will happen in sequence with each lake one by one at Lake Gonzales, Meadow Lake, Lake Placid, and Lake McQueeney, in that order. Hickman said it would take three days to drain each, a controlled drawdown timed in consultation with the Texas Parks and Wildlife Department.
“That was what they recommended we do in order to kind of do some environmental assessments as the water level was coming down,” Hickman said.
For many nearby residents and businesses, losing the lakes means losing an economic driver to the area. Boat and water ski shops, bait stores, homes, rental properties, real estate firms, and other businesses depend on the lakes that within a month will start going dry.
“They’re not just draining the lakes, they’re draining the economy,” said Tess Coody-Anders, a Trinity University marketing vice president who lives near Lake McQueeney and whose husband owns real estate agencies in New Braunfels and Seguin.
The draining of the lakes also means that GBRA will lose the revenue from the hydropower they generate using the flow of water. Hydropower earned the GBRA an average of approximately $2.6 million per year over the last 10 years, GBRA communications manager Patty Gonzales said. Hickman said that hydropower revenue was used entirely to cover the cost of maintaining the dams, which were all built by “private developers” between 1928 and 1932.
“Those expenses were much higher than the revenue produced,” he said.
The GBRA now estimates that repairing all six dams would cost $180 million.
“That’s a comprehensive overhaul, not just of the spillgates themselves, but everything you need to do to address a 90-year-old structure,” Hickman said.
Some residents in the area are questioning whether the costs would have to be so high or whether less expensive solutions might be available. Others are trying to come up with ways to raise the money through a taxing authority that’s independent of the GBRA.
Harmon said his group is working to gather support to create a water control and improvement district that could raise funds via an ad valorem tax on property owners near the lake. He said he’s seen estimates that repairing that dam could cost $26 million; the GBRA’s estimate is closer to $30 million.
Creating such a district would require voter approval. Harmon said they are hoping to put the issue on the local ballot in May 2020.