Don't Move a Mussel

Quagga mussels infest a boat propeller at Lake Mead

NPS Photo

Protect Your Waters - Don't Move a Mussel!

Zebra and quagga mussels are small non-native aquatic hitchhikers. They are invading freshwater habitats at an alarming rate.

At this time, Lake Amistad does not have zebra or quagga mussels, but zebra mussels are present in north and central Texas water bodies. If zebra and quagga mussels were to be introduced into Lake Amistad from a boat coming from an infested lake, they could rapidly spread to potentially coat every available surface, clog pipelines in Amistad Dam, damage machinery, harm fishery resources, change the reservoir ecosystem, and foul the water of Lake Amistad with their waste.

New Texas Laws Affecting Boats Operating in Public Fresh Water
A new Texas Parks and Wildlife regulation, effective July 1, 2014, requires all boats operating on public fresh water anywhere in Texas (including Lake Amistad) to be drained of all water after use to help combat the further spread of zebra mussels and other invasive species. This rule includes all types and sizes of boats whether powered or not, personal watercraft, sailboats, kayaks/canoes, or any other vessel used to travel on public waters.

Boaters can take a few simple precautions to help ensure they are in compliance with the law:

  1. Clean your boat, trailer, and gear by removing all plants, animals, and foreign objects.
  2. Drain all water from the boat, including the motor, bilge, live wells, and bait buckets, before leaving the lake.
  3. Dry the boat and trailer for a week or more before entering another water body. If unable to let it dry for at least a week, wash it with a high pressure washer and hot (at least 140-degree), soapy water.
To learn more, including which Texas lakes are infested with zebra mussels, visit:

Why Should We Be Concerned About Mussels?
Zebra and quagga mussels pose a great ecological and financial threat.

They grow and reproduce exponentially. A single female can produce up to one million eggs a year. Even if only ten percent of the offspring survive, there would be 10 septillion mussels in the waterway at the end of five years.

They clog water infrastructure, impacting water supply and quality. They attach to most underwater structures and can form dense clusters that impair facilities and impede the flow of water. They clog intake pipes and trash screen, canals, aqueducts and dams. The mussels also degrade water quality and can alter the taste and smell of drinking water.

They have significant ecological impact. They have the ability to change aquatic ecosystems and native plant and animal communities. The amount of food they eat and the waste they produce had life-altering effects on the ecosystem and can harm fisheries. As filter feeders, these species remove large amounts of microscopic plants and animals that form the base of the food chain, leaving little or nothing for native aquatic species. They have recreational impact. These mussels encrust docks and boats, and can get into engine cooling systems causing overheating and damage. The weight of attached mussels can sink navigational buoys, breakwaters, docks and small vessels.

They have significant economic impact. The maintenance costs for power plants, water treatment facilities and water delivery infrastructures increase, so does the cost of food and utilities. In the Great Lakes area, maintenance costs in water treatment plants, power plant intakes and dams have been in the billions of dollars. The destruction of native fisheries also has a wider economic impact in terms of tourism and recreation dollars not spent.

They are very difficult to kill. In only one instance have managers been successful in eradicating zebra mussels, and that was an isolated 12-acre quarry in Virginia. A large volume of chemical was used to treat the water and kill adults and larvae. Eradicating or treating zebra or quagga mussels in large water bodies and/or connected waterways may not be possible, so prevention is very important.

They spread very quickly to other water bodies. Mussels can spread to other bodies of water by attaching to boat hulls and anchors, trailers, and fishing equipment. Larvae can be transported in bilge water, ballast water or live bait wells. Mussel larvae also disperse naturally and can be carried by water currents to other lakes or reservoirs downstream or through water diversion.

Last updated: October 8, 2014

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