The what, when, where, how and why of LCRA’s program to lower Lake Austin

The Lower Colorado River nAuthority is set to lower nLake Austin in January.

The Lower Colorado River nAuthority is set to lower nLake Austin in January.

The Lower Colorado River Authority, which manages the Lower Colorado River to provide water and power services from the Hill Country to the Gulf Coast, will be lowering Lake Austin in early 2017, according to an announcement issued Oct. 21 by the agency.

The plan to lower lake levels—both in Lake Austin and upstream at Lake LBJ—will help alleviate the growth of nuisance vegetation, including hydrilla, which has previously plagued the waterway. The effort also allows residents to make needed repairs to their docks and bulkheads, according to the LCRA.

The agency last lowered Lake Austin in 2011 and lowered Lake LBJ in 2008.

What: Lake Austin will be decreased by about 10 feet mean sea level from its normal operating range of 491.8-492.8 feet msl down to a range of 481.2 msl-482.8 feet msl. As of Nov. 7, Lake Austin was at 491.92 feet msl and lakes Travis and Buchanan—the reservoirs that hold the area’s primary drinking water supply—were 98 percent full, according to the LCRA.

When: Lake Austin will be lowered from Jan. 2-Feb. 13, with the first two to three weeks devoted to the drawdown process. The LCRA will begin refilling the lake Feb. 9.

Where: Lake Austin and Lake LBJ

How: Lake Austin water is provided to downstream users and also fulfills environmental flow requirements in Matagorda Bay along the Gulf Coast. Normally, water from Lake Travis is used to replenish these flows back into Lake Austin. During early 2017, the LCRA will not send the water downstream from Lake Travis to refill the lake levels downstream users.

Why: The city of Austin requested that LCRA conduct a drawdown of the lake to provide an opportunity for lakeside property owners to conduct needed repairs to their bulkheads and boat docks and stay ahead of vegetation problems such as hydrilla. When the lake level is lowered, the aquatic plants are exposed to cool, dry air that kills off their leaves and stems.