Lake Marble Falls is infested with zebra mussels, the Texas Parks and Wildlife Department announced December 12. Biologists discovered established and reproducing populations of the invasive species in the lake this fall.
That makes three Highland Lakes with an infestation; Travis and LBJ are also on the list.
Along with Lake Marble Falls, the department confirmed Thursday that Granger Lake, located east of Georgetown and north of Taylor, also has an established population of zebra mussels.
In July, officials determined that Lake LBJ was infested and predicted that zebra mussels would spread downstream. This fall, Lower Colorado River Authority biologists found zebra mussels as well as their larvae at multiple sites in Lake Marble Falls.
Though zebra mussels are tiny, they amass in large colonies that can cover water intakes, docks, boats, and shorelines.
“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.”
According to Texas Parks and Wildlife, 19 lakes across five river basins have been determined to be infested. Ten more have tested positive for the presence of the species.
The zebra mussel is native to Eurasia and believed to have arrived in North America in the late 1980s, first in the Great Lakes region. It has since spread across numerous states along the Mississippi River and made it as far west as California. The species also can be transferred by watercraft that haven’t been properly cleaned.
“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 moved into any new river basins since 2017,” said Monica McGarity, 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.”
Texas Parks and Wildlife officials recommend that boat owners and marina staff follow proper decontamination procedures when moving boats or barges from zebra mussel-infested waters to another body of water. In these situations, “cleaning, draining, and drying” isn’t enough, according to McGarity. The tiny mussels can hide — even in larger numbers — in crevices and other hidden areas. Boat owners or marina operators moving a boat or barge under these circumstances should contact the Texas Parks and Wildlife Department at 512-389-4848 for advice on the decontamination process.