Austin Watershed Protection stocks more grass carp in Lake Austin to help manage hydrilla

Austin, TX – Austin Watershed Protection released an additional 2,790 sterile grass carp into Lake Austin on May 1 to help manage hydrilla, a non-native aquatic plant. Hydrilla is growing in approximately 37% of the lake, up from 30% in September. The grass carp were released near Tom Miller and Mansfield Dams where there is the most hydrilla. 

Grass carp can be an environmentally friendly, lake-wide, management tool because they prefer to eat hydrilla over other plants. They were stocked to increase the population from five to eight fish per acre of hydrilla. Our goal is to slow down the growth of hydrilla and reduce its density without having a negative impact on the lake’s ecosystem.

Texas Parks and Wildlife conducted a survey of vegetation in Lake Austin in mid-February, estimating 592 acres of hydrilla. Recent conditions, including a warm winter and elevated nutrient inputs, have contributed to an increase in its coverage.

While hydrilla supports fish habitat and water quality, it can grow so dense that it becomes a problem for the environment and the community. Managing hydrilla responsibly is a long-term effort and it may take several seasons to see measurable reductions from the added grass carp.

Residents and visitors can take the following steps to help prevent the spread of non-native species, like hydrilla:

• Reduce or avoid the use of fertilizers in your landscape, especially if you live in areas that drain to Lake Austin;

• Clean, drain, and dry your boat, trailer, and gear before and after use; 

• Avoid swimming and boating through dense patches of underwater vegetation;

• If manually removing/raking hydrilla from your shoreline, be sure plants are properly disposed of or composted.

More information about hydrilla management in Lake Austin is available on our Plant Life in Austin's Lakes web page.

About Austin Watershed Protection

Austin Watershed Protection protects lives, property, and the environment of our community by reducing the impact of flooding, erosion, and water pollution. Visit AustinTexas.gov/Watershed to learn more.