Zebra Mussels

State regulations require all boats operating on public freshwater anywhere in Texas to be drained after use to help prevent the spread of zebra mussels. This includes the Highland Lakes and lakes Bastrop and Fayette.

The rules require draining of live wells, bilges, motors and any other receptacles or water-intake systems coming into contact with public waters.

Live zebra mussels have been discovered less than 100 miles from the Highland Lakes. They were found in Lake Belton in 2013, in Lake Waco in 2014, and in Stillhouse Hollow Reservoir southwest of Belton in 2016.​ The mussels have infested lakes in North Texas, and their discovery in Central Texas lakes increases their risk to the Highland Lakes. The mussels pose a threat to the lakes' ecosystem, utilities and the water recreation industry.


LCRA's Water Quality team works to keep invasive species out of Highland Lakes

Boaters can unknowingly transport the invasive zebra mussels from lake to lake because the larvae are microscopic and easily transported in live wells or bilges without being seen. Boaters need to clean, drain and dry their boats to keep Texas lakes safe from the mussels' spread.

LCRA has been educating boaters about the issue since 2011 and is coordinating with the TPWD to combat the spread of zebra mussels in Central Texas.

How zebra mussels harm lakes

Zebra mussels are highly invasive freshwater mussels that can take over a lake and alter aquatic ecosystems. They negatively impact native fish and mussels and spoil beaches with their sharp shells. They also wreak havoc for boaters by damaging boat hulls, boating equipment and boat docks. Zebra mussels also can clog water intakes, drastically increasing maintenance costs for utilities.

They feed on phytoplankton (floating algae) in the water column. Once established in a water body, they can over-filter a reservoir and remove important plankton and nutrients. In large numbers, they can change entire aquatic ecosystems by disrupting the food chain and over-clarifying water. The increased water clarity provides greater penetration of sunlight, potentially increasing nuisance aquatic vegetation.

Because they attach to hard surfaces, zebra mussels can clog pipes, increasing maintenance costs to utility companies. In severe cases, utilities have been forced to retrofit infrastructures to maintain their operations. Some utility plants pay hundreds of thousands of dollars a year to manage zebra mussel infestations.

Click here for additional zebra mussel pictures.

Where did they come from and how did they get here?

Originally from Russia, zebra mussels (Dreissena polymorpha) arrived in the United States in Lake St. Clair in Michigan in 1988. They came to the United States attached to ships and in the ships' ballast water, eventually migrating down the Mississippi River. By 1993, zebra mussels could be found in 16 states, including Arkansas, Oklahoma and Louisiana.

In Texas, they were discovered in Lake Texoma on the Red River in April 2009 before spreading to other North Texas lakes and other waterways.

How zebra mussels multiply

The larval form of the mussels, called veligers, are microscopic. They "free-float" with currents and are able to pass through dams and float down streams and rivers before attaching to hard materials as adults. The larvae also can be transported across river basins in boat live wells or in pipelines.

Zebra mussels become reproductively mature in about one year. Females produce tens of thousands of eggs per year, spawning between early spring and late summer. Within three weeks, they morph into adults and attach to any hard surface using byssal threads – strong, elastic strings that originate from within their shells.

What you can do to keep them out of your lake

Once they become established in a watershed, little can be done to stop the spread of zebra mussels. It is important that everyone take precautions to keep zebra mussels out of our Texas lakes and rivers. The most critical things you can do to help are to CLEAN, DRAIN AND DRY your boats.​Click here to watch a short video on how to properly clean a boat.

  1. Clean
    Inspect your boat, trailer and gear and remove any zebra mussels, vegetation or foreign objects that are found.
  2. Drain
    Drain all water from the boat, including the engine, bilge, live wells and bait buckets, before leaving the lake.
  3. Dry
    Open all compartments and live wells and allow the boat and trailer to sit completely dry for a week or more before entering another water body; or, wash your boat, trailer and any gear that has been in the water with a high-pressure washer and hot (at least 140-degree), soapy water.


Where can I learn more about zebra mussels and other invasive species?

LCRA: Send email to Bryan.Cook@lcra.org or call him at
512–473–3200, ext. 3258.



Visit the zebra mussels page of the Texas Invasives website to learn more about how you can prevent the spread of zebra mussels in Texas' rivers and lakes. The site also provides information on all types of invasive species – plants, animals, etc. – and has an online form to report invasive species sightings.



Monthly Water Quality Report

Learn about water quality conditions from LCRA’s Monthly Water Quality Report.