The excitement of warmer weather means that many will be planning to extract watercraft from winter storage.  Before you launch, it’s important you employ some serious spring cleaning on your craft to remove unwanted and potentially invasive hitchhikers.

With both rivers and reservoirs in Texas fighting a battle against the spread of numerous invasive species, ensuring that those that can be destructive and even deadly is of highest priority. 

February 27 – March 3, 2017, is National Invasive Species Awareness Week. It is held annually to raise awareness and identify solutions to slowing or stopping the spread of invasives such as zebra mussels and giant salvinia, two exotic, non-native invasive species that threaten aquatic wildlife, can limit access to recreation and damage watercraft, and can even threaten access to drinking water. 

What are they?


Zebra mussels are tiny freshwater mussels about the size of a fingernail that can multiply rapidly.  Adult females can produce over one million eggs per year. They feed on algae, eradicating the main source of food for native fish. They can cause consequential environmental damage, clinging to everything from boat motors to water pumps, clogging pipelines and causing millions of dollars in damages for water providers.

These mussels are commonly found attached to the bottom of watercraft or in areas where water can be stored such as bilges, allowing them to spread as boaters travel from lake to lake.  Since there are no natural predators in Texas for these mollusks, their population numbers only continue to increase and spread. Within the basin, zebra mussels have been found in lakes Belton, Stillhouse Hollow and Waco.

The Texas Parks and Wildlife Department requires everyone to clean, drain and dry their boats to prevent them from spreading to reservoirs that are not infected. Penalties and fines are enforced for those possessing or transporting invasive species including zebra mussels.


Another species that is as invasive as zebra mussels and a major threat to those wishing to enjoy boating and swimming in Texas is a plant called giant salvinia.  About the size of a quarter, the floating, rootless ferns are thought to have originated in Brazil. The plant was first found in Texas in 1998 and according to Texas Parks and Wildlife has since been reported in over twenty bodies of water. It remains one of the most troublesome invasive aquatic plants in Texas because it damages ecosystems by blocking out sunlight with its tremendous growth and decreasing oxygen needed by fish and other species to thrive. Within weeks, giant salvinia can form thick layers on the surface of lakes and rivers, preventing swimming, boating, and angling.

Giant salvinia has not yet been identified in the Brazos River basin but is prevalent in both the Trinity River basin to the north and the Lower Colorado River basin to the south.  With proper care, boaters can avoid moving the plant into the Brazos River basin. 

What do you need to do?

The Texas Parks and Wildlife Department gives you a checklist to fend off both zebra mussels and giant salvinia by following these simple steps to clean, drain and dry:

Clean all vegetation, algae, mud and other debris from the boat and trailer.  Power-washing with at least 140 degrees Fahrenheit all live wells and other water intake systems will help kill zebra mussels. To be effective, the water coming out of the systems also needs to reach 140 degrees to ensure the entire system was exposed.

Other alternatives to heat cleaning include using straight vinegar or a chlorine bleach and water solution (one-half ounce bleach to water).To effectively kill zebra mussels, the mixture should in contact with the mussels for 15 to 30 minutes. Once the treatment is complete, clean water should be used to flush the chemicals and dead mussels from the boat. Boat owners should be sure to check with their manufacturer before using these chemicals, so it will not void their warranties.

Anglers should also be sure to remove material from and wash all fishing tackle, downriggers and lines to prevent spreading small, larval forms of aquatic invaders.

Dry the vessel and associated equipment with the help of this calculator http://www.100thmeridian.org/emersion.asp. These drying times are approximations, and factors such as cooler air temperatures, higher humidity and whether or not the vessel is kept in dry storage should be considered.

By following these steps, you can help our waterways stay safe for recreational use and affordable for drinking water purposes.

To view a map of areas currently confirmed as infested or suspected to have an infestation of zebra mussels, go here.

If you find zebra mussels clinging to your watercraft, please contact your local Texas Parks and Wildlife Department after removing them.  The Texas Invasive website, here, can help you report it the mussels. 

For a visual reference, please adhere to these tips on where these invasive species might be hiding on/in your boat http://texasinvasives.org/zebramussels/.  For more information on giant salvinia go here.