Fish to Help Control Invasive Plant in Lake Austin

June 19, 2012 2:10 pm by: Laura Rice

Photo courtesy City of Austin Watershed Protection Department

Editor note: this story has been corrected. An earlier version of this story said the hydrilla was in Lady Bird Lake. It is in Lake Austin.

An invasive water plant called hydrilla has spread to more than a third of Lake Austin—over 560 acres. That’s a record high. Typically hydrilla affects less than 100 acres of the lake.

The City of Austin is using fish to fight the invasion.

The city will dump 3,000 Asian Grass Carp into Lake Austin later this month. These carp love to eat hydrilla.

“So they are really our long-term, any environmental conditions, control option that works the best,” said Mary Gilroy, environmental scientist with the City of Austin.

The drought and warm temperatures have helped the hydrilla thrive. Since the Lower Colorado River Authority isn’t pumping out water downstream for rice farmers this year, the current isn’t flowing as quickly—which also helps the hydrilla grow.

Hydrilla grows to be very thick and can clog up pipes that carry drinking water from the lake. It can also cause problems for those who use the lake for recreation.

“If the plants got thick enough it could be dangerous to use the lake because you can’t swim through the material when it gets really thick,” said Gilroy.

The carp being put into the lake are sterile so they won’t be able to reproduce. Asian Grass Carp aren’t native to North America and if they could breed, that could create a whole new set of problems for Lake Austin.

Over the next few weeks, the LCRA and the citizen group, Friends of Lake Austin, will release more fish into the lake.