AUSTIN (KXAN) — Lake Austin has transformed over the past few months. Thick, green patches of plants line the lake downstream near Tom Miller Dam. Boat docks seemingly surrounded by an undersea jungle.
After a long absence, Hydrilla is back.
“We have stories of Jet skis getting caught in the hydrilla,” said Eric Moreland, owner of Moreland Properties on Lake Austin and a member of Friends of Lake Austin.
For more than thirty years, Friends of Lake Austin has worked to stop the spread of hydrilla, an invasive plant that can jam up motors, wrap around swimmer’s legs and tangle up docks.
Now, Moreland and the Friends of Lake Austin are asking the city of Austin to drawdown the lake several feet, dropping water levels in an effort to help clear away the hydrilla before the problem gets worse.
Hydrilla and the very bad summer
In June, the city of Austin conducted a survey of hydrilla in the lake. At the time, only 5% of the lake had hydrilla blooms. In an effort to combat this, the city released around three hundred sterile grass carp, a small fish that feeds on the grass, into the lake.
“Throughout the summer, we saw it really bloom and get a lot worse,” Moreland said.
After the July 4th floods, sediment and debris poured into the lake. The city says that this event, plus warm water and air temperatures, led to hydrilla to spread rapidly. Initially, the city planned to do another survey in December.
The Friends of Lake Austin, believing the hydrilla had spread, hired a biologist to conduct an independent survey of the lake. That survey revealed 38% of the lake now had hydrilla in it. Those results were brought to the city, who then conducted a new survey and got similar results.
Austin’s history with hydrilla
In the early 2000’s, Lake Austin had a hydrilla problem. City of Austin records show that in 1999, less than 5% of the lake had hydrilla coverage. By 2012, that number had reached nearly 40%. At that time, the lake only had about 40% vegetation coverage in the lake.
The city brought sterile grass carp to the lake in 2003. According to city records, between 2003 and 2011, the city stocked 1,000 to 2,000 carp per stocking event. Between 2012 and 2013, the city stocked 3,000 to 9,000 carp per event.
While the sterile grass carp eat hydrilla, they also move to other plants once there is no hydrilla in the area. By 2014, there were a nearly 35,000 grass carp in Lake Austin.
Within three years, hydrilla vanished from Lake Austin. So did all other plant life. City records show that aquatic vegetation made up 0% of Lake Austin from 2016 to 2023.
Bass fisherman in Lake Austin
Lake Austin is one of the top bass fishing spots in the country. Fisherman come for miles to catch the little fellas, swimming in and around the hydrilla plants in the lake.
“If you want a bathtub in your backyard, that’s fine with me. But I want a healthy lake,” said Ryan Zolper, a fisherman who spends his time on the lake.
Zolper is one of many who’s concerned about the addition of more grass carp and the elimination of the hydrilla. Many fish use hydrilla for homes and food.
“I care a lot about protecting the bass fishery. It’s a big hobby for me, huge industry in the area and the country as well,” Zolper said.
Drawing down Lake Austin
Following the latest surveys, the city of Austin has upped the number of grass carp they are placing in the lake. The goal is five fish per acre of grass carp, bringing the total to around 1,900 sterile fish.
“It’s more of a maintenance level. It’s really not going to do much,” Moreland said experts told him.
He and the Friends of Lake Austin are pushing for additional measure, a draw down of Lake Austin. “We need to push the city to to really request the [Lower Colorado River Authority (LCRA)] to do the drawdown in January,” he said.
The LCRA manages the highland lakes, including Lake Travis and Lake Austin. Moreland said a drawdown will help kill off the hydrilla and give homeowners a chance to do maintenance.
The lake has been drawn down before, but the last time was nine years ago.
During a virtual town hall on Oct. 16, Moreland presented data from Texas Parks and Wildlife that showed that past drawdowns, plus grass carp, helped reduce the hydrilla population.
At the same townhall, the city of Austin presented counter data that showed that drawdowns did not help with hydrilla. After some drawdowns, hydrilla increased, according to their data. A city memo also supported this conclusion.
Moreland hopes that the city can get the LCRA to agree to the drawdown sooner, rather than later. He wants to give homeowners a chance to prepare for the change.
“We want to be proactive versus reactive,” he said.
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