Key elevations for Lake Travis during floods

​LCRA operates Lake Travis and Mansfield Dam during floods under U.S. Army Corps of Engineers regulations and protocols. These protocols determine how much water LCRA may release, depending on how much water is in the Lake Travis flood pool and downstream conditions. LCRA makes controlled releases of floodwater through Mansfield Dam using any combination of three hydroelectric generating units and 24 floodgates. Water would flow over the spillway of Mansfield Dam should Lake Travis rise above 714 feet above mean sea level (feet msl).

 

Guide to the numbers:

681 feet msl: Lake Travis is considered full for water supply purposes at 681 feet msl. (At this level Lake Travis holds 1.13 million acre-feet, the amount of water it would take to fill more than 1.1 million acres to a depth of 1 foot or about 369 billion gallons.)

681 to 683 feet msl: When Lake Travis is forecast to rise to between 681 and 683 feet msl, LCRA may release up to 7,500 cubic feet per second (cfs), as long as even with the releases, the river stays below specified levels at three control points on the Colorado River downstream of the dam.

683 to 710 feet msl: When Lake Travis is forecast to rise to between 683 and 710 feet msl, LCRA may release up to 30,000 cfs, as long as even with the releases, the river stays below specified levels at three control points on the Colorado River downstream of the dam.

When Lake Travis is forecast to rise to between 681 ft msl and 710 ft msl, releases from Mansfield Dam may be reduced or stopped if the releases, when combined with local inflows below the dam, are forecast to cause stage or streamflow at Austin, Bastrop or Columbus to exceed the following levels:
Location​Control Stage (feet)​Control Flow (cfs)
​Austin33.030,000​
​Bastrop​27.2​45,000
​Columbus​35.5​50,000
cfs: cubic feet per second

 

710 to 714 feet msl: When Lake Travis is forecast to rise to between 710 and 714 feet msl, LCRA may release up to 50,000 cfs as long as even with the releases, the river stays below specified levels at three downstream control points on the Colorado River. (The highest level ever reached on Lake Travis was 710.44 feet msl on Dec. 25, 1991.)

When Lake Travis is forecast to rise to between 710 and 714 ft msl, releases from Mansfield Dam may be reduced or stopped if the releases, when combined with local inflows below the dam, are forecast to cause streamflow at Austin, Bastrop or Columbus to exceed the following levels:
Location​Control Flow (cfs)
Austin50,000​
​Bastrop​50,000
Columbus​50,000
cfs: cubic feet per second

714 to 722 feet msl: Water flows over the spillway of Mansfield Dam when Lake Travis rises above 714 feet msl. If Lake Travis is forecast to rise to between 714 and 722 feet msl, LCRA may release up to 90,000 cfs, including any flow over the spillway. Releases are not limited by downstream conditions.

722 to 750 feet msl: If the elevation of Lake Travis is forecast to rise between 722 to 750 feet msl, LCRA determines the amount of water to be released considering the dam's structural integrity. Releases are not limited by downstream conditions.

750 feet msl: This is the top of Mansfield Dam.

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