TPWD Fall Zebra Mussel Sampling Found No New Infested Lakes

TPWD Fall Zebra Mussel Sampling Found No New Infested Lakes

AUSTIN – The Texas Parks and Wildlife Department found no new lakes infested with invasive zebra mussels during recent statewide early detection and monitoring. TPWD and partners monitor more than 60 lakes for early detection or population monitoring of zebra mussels.

“It’s clear that boaters’ actions can help to prevent the spread of zebra mussels,” said Monica McGarrity, TPWD Senior Scientist for Aquatic Invasive Species Management. “We need their continued vigilance to protect the lakes we love. Keep cleaning, draining, and drying your boats and checking anchors for zebra mussels. If your boat has been stored in the water on a lake known to have zebra mussels, it will need to be decontaminated before it’s moved to another lake. We ask boat owners, boat haulers and marinas to contact us for guidance on how to have the boat properly decontaminated.”

In addition to finding no new lakes infested with zebra mussels in Fall 2018, they also haven’t been found in a new river basin since June 2017.

“Right now, just five of Texas’ 17 river basins have zebra mussels,” McGarrity said. “Once zebra mussels spread to a new basin there is always potential for downstream spread, but a boat can move them downstream in a single day. Only boats, barges, and other equipment used in the water can transport zebra mussels upstream or to new river basins. We encourage all lake users to keep an eye out for mussels attached to other watercraft as well as on shorelines and docks and report them to us as soon as possible.”

As of March 2019, 15 water bodies are listed as infested with zebra mussels, meaning they have an established, reproducing population; and six water bodies are listed as positive, meaning zebra mussels have been detected on more than one occasion. Eight water bodies are currently listed as suspect, meaning zebra mussels or their larvae have been found only once in recent history, with the most recent lake to be listed as suspect being O.H. Ivie Lake.  A status map and full list of these lakes can be found on the TPWD website.

Additionally, zebra mussel DNA—a cautionary finding that doesn’t indicate that live zebra mussels are in the waterbodies – has been found in several Texas lakes, including recently in Lake Amistad near Del Rio, which is managed by the National Park Service. This finding is a strong reminder that boaters need to be especially thorough on prevention measures when traveling to and from lakes.

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 to prevent the transfer of zebra mussels and other invasive species. Zebra mussel larvae are microscopic and can survive for days in residual water and adults can survive even longer out of water, especially in cooler months. The requirement to drain applies to all types and sizes of boats whether powered or not – personal watercraft, sailboats, kayaks, canoes or any other vessel used on public waters.

The rapidly reproducing zebra mussels can have serious economic, recreational and environmental impacts on Texas reservoirs and rivers. Zebra mussels can harm aquatic species, cause harmful algal blooms, cover rocks, beaches, hard surfaces with sharp shells, clog water intakes, damage or increase maintenance on facilities using raw surface water, and damage boats and motors left in infested waters.

Although TPWD and partners continually monitor for zebra mussels in Texas lakes, anyone who finds zebra mussels in lakes where they haven’t been found before or who spots them on boats, trailers or equipment that is being moved is encouraged to help prevent new introductions of zebra mussels by reporting the sighting to TPWD immediately at (512) 389-4848 or by emailing photos and location information to

More information about zebra mussels can be found online at A short instructional video on how to properly clean, drain and dry boats and equipment can be found on the TPWD YouTube channel at