Lake Travis Reaches 99 Percent Full

Lake Travis boat

After several years of near historic drought levels, Lake Travis is 99 percent full. As of March 15, 2016 at noon, Lake Travis reached 680.34 feet above mean sea level, just shy of the 681 feet above msl that indicates the lake is “full.” Its current storage is 1,122,336 acre feet of water, just short of the full level of 1,134,956 acre feet of water.

What happens now?

Lake Travis actually can hold more water than its 681 feet. Its historic high occurred in 1991 when it reached 710.44 feet above msl, and its 100-year flood mark would be 722 feet above msl. However, once the lake goes above its full level of 681 feet, the Lower Colorado River Authority begins floodgate releases at Mansfield Dam under the direction of the U.S. Army Corps of Engineers. With 24 floodgates, the LCRA may choose to open one, a few, or all, depending on numerous factors, such as weather expectations and whether there is any flooding before or after the dam.

Mansfield Dam is 318 river miles upstream from the Gulf of Mexico and serves as a flood management tool for the entire region. It also provides water storage for the growing Central Texas area and hydroelectric power. Built from 1937 to 1942, the spillway elevation is 714 feet above msl, and the top of the dam reaches 750 feet above msl. It can discharge more than 133,400 cubic feet per second from its 24 floodgates and three turbines. In total, it can store 369.8 billion gallons of water.

As of now, Lake Travis is the only part of the Highland Lakes chain specifically designed to contain floodwaters. However, LCRA is constructing the Lane City Reservoir in Wharton County in order to hold an additional 90,000 acre feet of water. The reservoir is expected to be completed by 2017 and should reduce demands on Lake Travis and the other Highland Lakes.