AUSTIN – The Texas Parks and Wildlife Department (TPWD) has designated Lake Walter E. Long in Travis County as “infested” with zebra mussels, signifying an established, reproducing population in the lake.

Walter E. Long had already received a “positive” designation following the repeated detection of zebra mussel larvae in October 2018 and May 2019. However, subsequent searches for settled mussels conducted as recently as 2021 did not detect any juveniles or adults. In early August of this year, City of Austin Watershed Protection biologists conducted shoreline searches for zebra mussels and found two adults in the lake, indicating the presence of an established population.

Additionally, private-access Diversion Lake in Medina County is also now fully infested with zebra mussels. Bandera County River Authority and Groundwater District staff found numerous settled zebra mussels in the lake in July, indicating the presence of an established population. Since Diversion Lake is immediately downstream of fully infested Medina Lake, downstream dispersal likely led to the infestation.

“Unfortunately, zebra mussels have now spread to 34 Texas lakes, with 30 now fully infested, but there are far more lakes in Texas that still haven’t been invaded and are at risk,” said Brian Van Zee, TPWD Inland Fisheries Regional Director. “Each boater taking steps to clean and drain their boat before leaving the lake and allowing compartments and gear to dry completely when they get home can make a big difference in protecting our Texas lakes.”

Because zebra mussels are most often transported on or in boats, boaters play a critical role in preventing them from spreading to new lakes. Zebra mussels attach to boats and anything left in the water, including anchors, and can survive for days out of water, often hiding in crevices where they may escape notice. Their larvae are microscopic and invisible to the naked eye, meaning they can be unknowingly transported by boats in residual water.

TPWD urges boaters to clean, drain and dry their boats and gear before traveling from lake to lake. Remove plants, mud and debris, drain all the water from the boat and gear, and then open compartments once you get home and allow everything to dry completely for at least a week if possible.

If you have stored your boat in the water at a lake with invasive mussels, it is likely infested and poses an extremely high risk for moving these invasive species to a new lake. Before moving your boat, call TPWD at (512) 389-4848 for guidance on decontamination.

On top of the harm invasive species can cause to aquatic ecosystems, water infrastructure and the recreational experience at lakes, the transport of these organisms can result in legal trouble for boaters. Transporting prohibited aquatic invasive species in Texas is illegal and punishable with a fine of up to $500 per violation. It’s also the law that boaters must drain all water from their boat and onboard receptacles, including bait buckets, before leaving or approaching a body of fresh water. They must also remove all invasive plants from the boat, trailer, and tow vehicle before leaving a lake.

For more information on how to properly clean, drain and dry boats and equipment, visit the TPWD YouTube channel for short instructional video. To learn more about giant salvinia, zebra mussels and other invasive species in Texas, visit tpwd.texas.gov/StopInvasives.

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