The LCRA said the agency opens gates during flooding to move the water "in a more predictable and safe way," adding that "without the floodgates, flooding would overtop the dams and threaten the integrity of the dams." "Having operational floodgates on the dams allows us to manage flooding on the Colorado River by moving floodwaters downstream into Lake Travis, in which they can be temporarily stored until LCRA can release them in a controlled manner." "Heavy rains here can quickly transform into walls of fast-moving water with great destructive potential," Hofmann said. In 1957, ending a decadelong drought, floods forced the LCRA to open as many as six gates at Mansfield Dam on Lake Travis for the first time as part of flood management operations. While the LCRA was still securing federal funding to resume construction of Buchanan Dam in 1935, a June flood that struck the lower Colorado River basin also swept through downtown Austin. "It’s important to note the dams were originally built to help tame the Colorado River after flooding time and again devastated the city of Austin and downstream communities," Hofmann said. Hofmann and the LCRA point out that Austin and other communities that cling to the sides of the Colorado River sit in the so-called Flash Flood Alley, which means we're vulnerable to intense flooding because of steep terrain, shallow soil and very rapid rainfall rates. A buoy line will cordon off the construction area to give crews more room to work, the LCRA said. Will boaters still be able to use Lake LBJ?īoaters will be allowed on Lake LBJ during the project, but the LCRA will expand the area that's already off-limits to boaters from 150 feet to 300 feet upstream from Wirtz Dam. The LCRA expects it will take about two months to replace each floodgate, which puts the completion date for the entire project sometime in 2025. “Dams along the Highland Lakes play a critical role in managing floodwaters, and we have to maintain their readiness at all times.” “We could do this project more quickly if we replaced multiple floodgates at once, but we are in Flash Flood Alley, and that is not a viable option,” said John Hofmann, the LCRA's executive vice president of water. Why is the LCRA replacing the floodgates?Īccording to the LCRA, the agency is upgrading each gate at Wirtz Dam "with a new custom-made floodgate that meets today’s engineering standards." To keep the dam operating, the gates will be replaced one at a time. Ferguson Power Plant was built nearby in Llano County. The LCRA added a 10th gate in 1974 when the original Thomas C. Wirtz was built in 1951 to create Lake LBJ, with nine gates to pass floodwaters downstream. Wirtz Dam connects Lake LBJ, which sits behind it, to the next car forward, Lake Marble Falls. Think of the lakes as train cars carrying passengers, and when one car gets overloaded, the passengers move to the next car forward. Wirtz Dam is one of the six dams on the Colorado River that form the Highland Lakes upstream from Austin. So what does the LCRA's renovation of floodgates mean for Central Texas, and how will it affect people in Austin? Here's what we know: What's Wirtz Dam? On a side note: Lady Bird Lake is not one of the Highland Lakes. The LCRA, which runs the dams, uses them to manage the sometimes flood-swollen river and generate hydroelectric power. If you're new to Austin, you should know that the Highland Lakes are actually the Colorado River, separated by a series of dams. Floodgates at Wirtz Dam, which forms Lake LBJ upstream from Austin on the Colorado River, will be replaced in a $76 million, three-year project, the Lower Colorado River Authority announced earlier this year.
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