TPWD: Zebra mussels confirmed in Marble Falls, Lake Granger

The Texas Parks and Wildlife Department has added two lakes to its statewide list of waterways that are confirmed to be infested with zebra mussels.

The Lower Colorado River Authority (LCRA) biologists found the presence of zebra mussels recently in Lake Marble Falls. They found settled zebra mussels as well as larvae in multiple test spots on the lake.

After they confirmed that Lake Lyndon B. Johnson had zebra mussels, it was expected that the invasive species would eventually make its way down stream to Lake Marble Falls.

TPWD and the LCRA are urging lake users to take preventive steps to keep the creatures from spreading any further upstream.

“We continue to work closely with our partners at Texas Parks and Wildlife to monitor the presence of zebra mussels in the Highland Lakes,” said Bryan Cook, LCRA Manager of Water Quality Protection. “It’s important to do what we can to stop zebra mussels from spreading to new lakes. We encourage boaters to continue to clean, drain and dry their boats and trailers, as well as to drain all water from boats and onboard receptacles when moving from lake to lake.”

Granger Lake tested positive in May after multiple areas showed signs of zebra mussel larvae.

The lake has now been upgrade to “infested” after Brazos River Authority staff found adult zebra mussel settlements throughout the lake.

Granger is the second lake in the San Gabriel River basin to be infested, the first was Lake Georgetown that was declared infested in 2017.

“Although it’s saddening every time we find zebra mussels in a new lake or confirm that a lake is fully infested as we have with Marble Falls and Granger, it is still encouraging that zebra mussels have not been moved into any new river basins since 2017,” said Monica McGarrity, TPWD Senior Scientist for Aquatic Invasive Species Management. “Only boats can move zebra mussels upstream or into new river basins. It is important for all lake users to protect our lakes by cleaning, draining and drying their boats and equipment every time they leave the water.”

Boat owners and marina staff are encouraged to be diligent about decontamination procedures when a boat is taken out of water to be stored or used on another waterway.

“Cleaning, draining and drying is not enough to prevent zebra mussels from hitching a ride on a boat or barge that has been stored in the water on a lake with zebra mussels,” McGarrity said. “These vessels pose the highest risk for moving them and causing new infestations because the mussels attach themselves in crevices and other hidden areas, often in large numbers. If you are moving a boat, call TPWD at (512) 389-4848 and we’ll be happy to advise you on the proper procedures to decontaminate your boat and help you through the process.”

As of November, there were zebra mussels confirmed at 29 Texas lakes across five river basins.

Zebra mussels can reproduce rapidly and can have serious negative economic, recreational and environmental impacts on lakes and rivers.

The mussels can harm other aquatic species, encase rocks, cover beaches and hard surfaces, clog water intakes and damage equipment and boats.   

TPWD and partners monitor for invasive mussels in Texas lakes, but anyone who finds them in lakes where they haven’t been found before or who spots them on boats, trailers or equipment that is being moved should help prevent new introductions by immediately reporting the sighting to TPWD at (512) 389-4848 or by emailing photos and location information to aquaticinvasives@tpwd.texas.gov.

It is against the law to possess or transport (knowingly or unknowingly) zebra mussels, dead or alive, in the state.

Boaters are required to drain all water from a boat and onboard receptacles before leaving or entering a body of fresh water to prevent the spread of these mussels or other invasive species.

The mussels’ larvae are microscopic and can survive for several days in small amounts of water. The adult zebra mussels can survive for even longer outside of water, especially in colder months.

More information about zebra mussels can be found online at tpwd.texas.gov/ZebraMussels. A short instructional video on how to properly clean, drain and dry boats and equipment can be found on the TPWD YouTube channel at https://youtu.be/DMlEwbXmLx8.

Claire Kowalick, a senior journalist for the Times Record News, covers local government, military and MSU Texas. If you have a news tip, contact Claire at ckowalick@gannett.com.

Twitter: @KowalickNews