The Lower Colorado River Authority recently completed a 12-year, $51-million renovation of Buchanan Dam, the largest of the dams that form the chain of Highland Lakes. The dam is 145.5 feet high and almost 2 miles long. It is one of the longest multiple-arch dams in the world. Courtesy photo
The completion of a $51-million upgrade at Buchanan Dam could lead to raising the lake level to 1,020 feet mean sea level from 1,018 feet mean sea level year-round, according to a news release from the Lower Colorado River Authority. A new, more efficient floodgate system will enable the LCRA to more quickly respond to flooding, making it feasible to leave more water in the reservoir. An agreement from FEMA is necessary to implement the change.
It took 12 years and $51 million to renovate the 83-year-old dam that forms Lake Buchanan, the largest in the chain of Highland Lakes. The long timeframe was necessary because the extensive rehabilitation work could only be performed on a few of the dam’s 37 floodgates at a time.
“This is a remarkable dam and a remarkable project,” said Timothy Timmerman, chair of the LCRA Board of Directors. “The dam was completed in 1938 using technology and engineering standards of the day. Without changing the dam’s structure, we were able to upgrade the floodgates to meet today’s engineering standards, as well as make them able to respond to flooding more quickly.”
In addition to strengthening each floodgate, crews added 30 stationary remote-operated hoists to enable LCRA to open the floodgates more quickly. The project also added two new traveling remote-operated hoists for the remaining seven floodgates. In the past, crews had to manually move the hoists from floodgate to floodgate. Steel bridge structures also were recoated to provide long-term protection.
“LCRA operates dams in the heart of Flash Flood Alley, and we take that responsibility very seriously,” said Phil Wilson, LCRA general manager. “We have to stay vigilant and ready to protect the water supply and respond to flooding at any time, and a significant part of that effort involves keeping our dams in excellent condition.
From fiscal years 2010 to 2020, LCRA invested more than $111 million in capital projects along the Highland Lakes, Lake Bastrop, and Lake Fayette. LCRA plans to invest an additional $83 million in these types of projects through fiscal year 2026.
In October 2020, LCRA completed a $10.8 million project to replace each of the floodgates at Tom Miller Dam in Austin and has begun a similar renovation project at Wirtz Dam in Horseshoe Bay. Gate rehabilitation projects also are underway at Mansfield and Starcke dams. Mansfield is in Austin, while Max Starcke is in Marble Falls.
Work on the dam:
strengthened all 37 floodgates and provided a 1-foot vertical extension on each floodgate to reduce the potential for overtopping and allow more time to open the floodgates during a flood;
removed and inspected all gate trunnions, replacing them as needed;
upgraded the dam’s electrical system;
provided stop logs to hold back water to allow work on the floodgates to take place in a dry environment;
upgraded security and safety features;
and recoated all of the hoist bridges.
With the project now completed, LCRA can begin conversations with FEMA about changing the maximum lake level. Under the current agreement with FEMA, the lake must be maintained at or below 1,018 feet mean sea level from May through October and 1,020 feet mean sea level the rest of the year because of concerns it would have been difficult to open the floodgates quickly if the need arose.
Any changes to the dam’s maximum operating level will take time, warned the LCRA, and once enacted would not mean the lake would be kept at 1,020 feet mean sea level year-round. Instead, a change in the maximum operating level would mean the lake could rise to that level when circumstances allowed. As a water supply reservoir, water from Lake Buchanan would continue to be used to meet water supply needs.