Key elevations for Lake Travis during floods

LCRA operates Lake Travis and Mansfield Dam during floods under U.S. Army Corps of Engineers (Corps) 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). Below is a summary of the Corps protocols.

Click on the colored ranges for more detail.

 

681 681 to 683 683 to 685 685 to 691 691 to 710 710 to 714 714 to 722 722 to 750

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, or the amount of water it would take to fill more than 1.1 million acres to a depth of 1 foot; about 369 billion gallons.)

back to graphic

681 to 683 feet msl: When Lake Travis is forecast to rise to between 681 and 683 feet msl, LCRA may release from 3,000 to 7,500 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.

back to graphic

683 to 685 feet msl: When Lake Travis is forecast to rise to between 683 and 685 feet msl, LCRA may release from 5,000 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.

back to graphic

685 to 691 feet msl: When Lake Travis is forecast to rise to between 685 and 691 feet msl, LCRA may release from 5,000 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. There are seasonal rules that guide how much water LCRA may release:

  • May and June, September and October: During these months, if Lake Travis is forecast to rise above 685 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 downstream control points on the Colorado River.
  • January-April, July, August, November and December (the rest of the year): During these months, if Lake Travis is forecast to rise above 685 feet msl, LCRA may release from 5,000 to 30,000 cfs, as long as even with the releases, the river stays below specified levels at three downstream control points on the Colorado River.

 

back to graphic

691 to 710 feet msl: When Lake Travis is forecast to rise to between 691 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.

back to graphic

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

back to graphic

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

back to graphic

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.

back to graphic

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.

back to graphic

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

back to graphic

Glossary

msl–mean sea level
cfs–cubic feet per second

Federal regulations guide operations of Mansfield Dam during floods: The Code of Federal Regulations, Title 33: Navigation and Navigable Waters, Part 208: Flood Control Regulations, § 208.19 Marshall Ford Dam and Reservoir (Mansfield Dam and Lake Travis), Colorado River, Texas.

back to graphic