Before you launch this holiday weekend, look out for hitchhiking mollusks

Before you launch this holiday weekend, look out for hitchhiking mollusks

Visiting a Brazos River Authority reservoir this weekend?

Make sure invasive species don’t come with you. Not only can they harm our water, but they can cost you.


It’s a message that bears repeating as yet more local bodies of water are finding zebra mussels, harming the recreational experience and damaging aquatic ecosystems. There are now 18 Texas lakes currently infested with invasive giant salvinia and 15 state lakes infested with an established, reproducing population of zebra mussels, according to the Texas Parks and Wildlife Department.

Without the help of every boater, this invasive species will only continue to spread by "hitching a ride" on a watercraft.

Here's how to stop it:

  • Clean: Remove all plants, animals, and mud and thoroughly wash the boat and trailer. Boats stored on infested waters may need to be professionally decontaminated.
  • Drain: Drain all water before leaving the area, including livewells, bilges, ballast, and engine cooling water.
  • Dry: Allow time for your boat to dry completely before launching in other waters.

“Memorial Day weekend is the unofficial kick-off to boating season in Texas, and while we want everyone to have a great time we also want them to avoid giving free rides to invasive species when they travel to new lakes,” said Brian Van Zee, TPWD Inland Fisheries Regional Director. “The best way to help keep Texas lakes fun for everyone and prevent the spread of destructive invasive species is to clean, drain and dry your boats and equipment – every time.”

The newest additions to the list of nine positive lakes where zebra mussels have been detected on more than one occasion include Lake Dunlap, Lake Walter E. Long and Lake Granger, located within the Brazos basin, according to the Texas Parks and Wildlife Department. The newest addition to the list of five suspect lakes where zebra mussels or their larvae have been found only once in recent history is Lake Placid.

“Most of the lakes that received upgraded classifications are downstream of infested reservoirs, so the likelihood that zebra mussel larvae would disperse and invade them was high,” Van Zee said. “But boaters still need to be extremely diligent about cleaning, draining and drying, because only boats, barges, and other equipment can transport zebra mussels upstream or to new river basins.”


Tiffany Morgan, BRA environmental and compliance manager, said there is still a big question whether zebra mussels will thrive in Lake Granger like they have in lakes Belton, Stillhouse and Georgetown.

“Granger is widely different in that it has a soft sediment bottom and lots of turbidity,” she said. “There is some question if zebra mussel veligers, who are distributed by water flows and like hard surfaces, will be able to colonize Lake Granger, like they have in the other lakes..”

Teams are already on the lookout.

“We have samplers deployed at various locations on the reservoir that are analyzed quarterly and have divers inspecting screens and pumps on a routine schedule and to date neither method has identified any attached adults,” Morgan said.

Why is it such a big deal?

Zebra mussels and giant salvinia remain some of the biggest threats to Texas lakes and other highly invasive species also can be spread or introduced by in-state and out-of-state lake users, including water hyacinth and quagga mussels.

Transporting prohibited invasive species in Texas is a Class C misdemeanor subject to a fine of up to $500 for the first offense, according to the Texas Parks and Wildlife Department.

Zebra mussels can block pipes that deliver water, attach themselves to the hulls of boats and can also hinder water recreational opportunities because of the sharp shells which can quickly multiply on beaches or docks. Zebra mussels also harm fish population as they remove plankton from the food chain, according to the National Wildlife Federation.

Those using kayaks, stand up paddleboards, wet suits and any other equipment that comes into contact with the water should also take care to clean, drain and dry gear, as microscopic zebra mussel larvae can survive on wet surfaces for up to three weeks, according to the Texas Parks and Wildlife Department.

All it takes is one trip to cause the damage. Protect the lakes you love and take the time to clean, drain and dry your water vessel every time.


For more information, go here. For questions about zebra mussels, boat inspection and decontamination, regulations, or what to do if you encounter an infested boat or suspect a watercraft is carrying zebra mussels, email AquaticInvasives@tpwd.texas.gov or call TPWD’s 24/7 hotline at 512-389-4848.