Zebra mussels spotted in Lady Bird Lake
Officials: Swimmers could spread invaders to Barton Springs.
Zebra mussels have been spotted in Lady Bird Lake, and Texas wildlife officials Thursday said they now consider Lake Austin to be “infested” with the invasive species.
The spread of the scourge means that swimmers who emerge from Lake Austin or Lady Bird Lake and jump into Barton Springs Pool without thoroughly drying off could put the iconic swimming hole at risk for infestation, Austin water quality officials warned.
Lady Bird Lake was upgraded to “suspect” status because several larvae were found in a plankton sample taken by the Lower Colo- rado River Authority, according to a statement from the Texas Parks and Wildlife Department.
Lake Austinis now considered infested because wildlife officials
confirmed it has an established, reproducing population of zebra mussels. Texas parks and LCRA staffers found adult zebra mussels and larvae in multiple locations, including Tom Miller Dam and the Pennybacker Bridge, wildlife officials said.
The infestation at Lake Austin and the discovery of microscopic zebra mussel larvae in Lady Bird Lake come less than a year after the animals were first spotted upstream in Lake Travis last June.
Zebra mussels can not only harm native freshwater species, but they also can worsen water clarity, cause algae blooms, litter beaches with sharp shells, clog water intakes at hydroelectric facilities, and damage boats and motors, wildlife officials said.
Monica McGarrity, whose team at Texas Parks and Wildlife monitors aquatic invasive species, said that once zebra mussels appeared in the Colorado River basin, they were likely to spread downstream.
“But downstream dispersal doesn’t spread zebra mussels to new river basins — boats do — and boats can spread them downstream more quickly,” she said.
McGarrity urged boat owners to “protect other river basins and prevent zebra mussels from spreading more quickly to other reservoirs by being extremely diligent about cleaning, draining and drying their boats and other gear every time they visit any lake or river.”
Austin city officials also are urging swimmers to thoroughly clean and dry all swimsuits, water shoes and other gear after swimming in Lake Austin or Lady Bird Lake before visiting any local swimming holes, including Barton Springs Pool.
Liz Johnston, a program coordinator with the city’s Watershed Protection Department, which monitors water quality in area reservoirs, said the city will begin posting signs on all the guardrails at Lady Bird Lake and at the entrances to Barton Springs Pool, warning swimmers and boaters about the zebra mussel danger and what precautions to take.
Even though swimmers aren’t allowed in Lady Bird Lake, people often fall from paddle boards into the water. If they then head to Barton Springs Pool for a swim, they could spread the larvae, Johnston said.
“For Parks and Wildlife it is a class C misdemeanor. They can write tickets, but they would have to see adult zebra mussels on a boat to enforce it,” she said, later noting that Lake Walter E. Long could be the next body of water affected. “I don’t think we can prove that anyone was swimming in an infected reservoir. We just want people to be aware.”
Despite the presence of the mussels, Austin’s drinking water supply is safe, Johnston said. They are more a nuisance for Austin Water, which will have to clean them out of intake pipes. All water is treated before it goes to homes and businesses, she said.
Getting rid of the mussels will be the biggest challenge.
“There are chemicals you can put in there that would kill them, but it would kill everything else,” Johnston said. “So that is not an option for our drinking supply.”
According to the Texas Parks and Wildlife Department:
14 bodies of water in five river basins throughout the state, including Lake Austin and Lake Georgetown, are infested with zebra mussels.
Five bodies are considered “positive,” meaning zebra mussels have been detected on more than one occasion.
Three bodies, including Lady Bird Lake, are deemed “suspected” of having zebra mussels.
Texas law prohibits anyone from intentionally possessing or transporting living or dead zebra mussels.
Boaters are required to drain all water from all craft, powered or unpowered, before leaving or entering rivers and lakes so zebra mussels and other invasive species don’t spread.
Wildlife officials say zebra mussels, which have been spreading across the United States since the first established population was found in the Great Lakes in 1988, can survive for days in or on boats moved from a lake.
Zebra mussel DNA has been identified in at least 10 other bodies of water in Texas during routine sampling in 2017, wildlife officials said.
Brian Van Zee, inland fisheries regional director for Texas Parks and Wildlife, said the presence of DNA is an alert for biologists and underscores the need for boaters to be vigilant about cleaning and draining their watercraft.
“Even though you may not see them, microscopic hitchhikers could still be hiding in your equipment,” he said.