The Texas Parks and Wildlife Department (TPWD) has detected invasive zebra mussels at Lake Brownwood in the Colorado River Basin, southeast of Abilene. Zebra mussel larvae were detected in plankton samples collected at two sites approximately three miles apart at Lake Brownwood in November. This is the second lake in the Upper Colorado River Basin where zebra mussels have now been detected, which indicates this species is continuing to spread westward.

To date, no adult mussels have been found in the lake. In late March, TPWD staff conducted intensive shoreline and substrate surveys at both locations where larvae were detected. In addition, surveys were conducted at a third marina site, but no settled juvenile or adult mussels were found at any of the sites.

“Zebra mussels are a highly invasive, non-native species that cause damage to boats as well as to infrastructure for water supply and control and other facilities using raw surface water,” said Monica McGarrity, TPWD Senior Scientist for Aquatic Invasive Species. “Zebra mussels also negatively impact the ecosystem, competing with native filter feeders and altering the food web and attaching to and harming native mussels. Their razor-sharp shells can litter shorelines and cover underwater hard surfaces, posing a hazard for humans.”

The public is asked to be on the alert for zebra mussels at Lake Brownwood on rocks, docks and other hard surfaces, and boats. Anyone who spots zebra mussels should immediately notify TPWD at [email protected] with photos. Zebra mussels attach firmly to hard surfaces and have triangular shells, often with tan/brown stripes and grow to approximately 1.5 inches long.

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 may also contaminate anchors or plants clinging to boats and can survive for days out of water. Their larvae are microscopic and invisible to the naked eye and can be unknowingly transported in residual water in boats. Boaters are urged 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 up compartments once you get home and allow everything to dry completely.

If you have stored your boat in the water at a lake with zebra mussels, it is likely infested with zebra mussels and poses an extremely high risk for moving this invasive species to a new lake. Before moving your boat to another lake, call TPWD at (512) 389-4848 for guidance on decontamination. The transport of aquatic invasive species can result in legal trouble for boaters or transporters. Transporting prohibited invasive species in Texas is illegal and punishable with a fine of up to $500 per violation. Boaters are also required to drain all water from their boat and onboard receptacles, including bait buckets, before leaving or approaching a body of fresh water.

Additionally, anyone who spots zebra mussels on boats, trailers or equipment that is being moved should immediately report the sighting to TPWD at (512) 389-4848.

TPWD and partners monitor for zebra mussels in Texas lakes, but anyone who finds them in lakes where they haven’t been found before should report them by emailing photos and location information to [email protected].

A status map showing all lakes where zebra mussels have been found in Texas is online at tpwd.texas.gov/ZebraMussels. For more information on how to properly clean, drain and dry boats and equipment, visit the TPWD YouTube channel for a short instructional video.

Information for marinas and owners of boats stored in the water on lakes with zebra mussels can be found on the TPWD website. To learn more about zebra mussels and other invasive species in Texas, visit tpwd.texas.gov/StopInvasives.