AUSTIN —Lake Austin is now classified as positive for invasive zebra mussels after biologists discovered them in the reservoir last week. Lake Austin is the third Central Texas reservoir where zebra mussels have been found this year, and the second in the Colorado River basin.
After a single zebra mussel larva was identified from a plankton sample collected near Tom Miller Dam and later verified by DNA testing, staff from Texas Parks and Wildlife Department Inland Fisheries and the City of Austin searched for zebra mussels on hard surfaces around the lake. They identified several half-inch adult zebra mussels on multiple marina floatation devices and a barge near the Walsh Boat Landing Aug. 9.
Although the adult zebra mussels were found just a little over a month after upstream reservoir Lake Travis was found to have an established, reproducing population, biologists cannot determine whether the Lake Austin zebra mussel presence is the result of downstream spread from Lake Travis or whether it’s the result of an infested boat coming into the lake.
“Passive downstream spread is a concern any time we have an infested reservoir, but boats can move adult mussels to a lake much quicker,” said Monica McGarrity, TPWD aquatic invasive species team lead.
Lake Austin is a 1,589-acre reservoir on the lower Colorado River. The lake is formed by Tom Miller Dam, which is owned by the city of Austin and operated by the Lower Colorado River Authority. The lake is used for hydroelectric generation and water supply, and is a popular recreation destination. With seven boat ramps and a high level of recreational use by boaters that travel to infested lakes, Lake Austin – like other Highland lakes—has long been identified as having a high risk of zebra mussel invasion.
“Both Lake Austin and Lake Travis have a lot of boating traffic and a lot of use,” said Brian Van Zee, Inland Fisheries regional director. “We really need all boaters to be diligent in their ‘clean, drain and dry’ efforts before leaving a lake. All boaters need to remove their drain plugs and be sure to pump as much water out of the ballast tanks, livewells and bilges as possible because zebra mussel larvae can survive in very little water.”
In Texas, it is unlawful to possess or transport zebra mussels, dead or alive. Boaters are required to drain all water from their boat and onboard receptacles before leaving or approaching a body of fresh water in order to prevent the transfer of zebra mussels. The requirement to drain applies to all types and sizes of boats whether powered or not: fishing boats, wakeboarding and ski boats, personal watercraft, sailboats, kayaks, canoes or any other vessel used on public waters.
Although it is not yet known whether Lake Austin has an established, reproducing population of zebra mussels, TPWD biologists will be working with LCRA and the City of Austin to continue and expand monitoring efforts and install signage at boat ramps to remind boaters of the importance of cleaning, draining and drying their boats.
“We want folks to be aware of zebra mussels in Lake Austin and to let us know if they’re finding them in other areas of the lake,” McGarrity said. “As we continue to monitor the population that location information will be very helpful.”
Users of downstream Lady Bird Lake should also take care to clean, drain and dry kayaks, stand up paddleboards, and any other equipment that comes into contact with the lake before putting them into another water body.
Since zebra mussels were first found in Texas in 2009, 11 lakes in five river basins have been infested, meaning they have an established, reproducing population – Belton, Bridgeport, Canyon, Dean Gilbert (a 45-acre Community Fishing Lake in Sherman), Eagle Mountain, Lewisville, Randell, Ray Roberts, Stillhouse Hollow, Texoma and Travis.
Zebra mussel-positive lakes – meaning zebra mussels or their larvae have been detected on more than one occasion – include Lavon, Livingston, Waco, Worth, Fishing Hole Lake (a small lake connected to the Trinity River below Lake Lewisville), and now Austin.
More information about zebra mussels can be found online at tpwd.texas.gov/ZebraMussels.