Aquatic Invasive Species

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4 minutes, 51 seconds

This video provides a brief overview of Amistad National Recreation Area's aquatic invasive species program. The park would like to thank the Del Rio High School CTE Media Tech Program students from the 2021-22 academic year for their outstanding work on this video.

zebra mussel
Zebra Mussel

US Geological Survey - Amy Benson

In Texas, it is illegal to possess or transport quagga or zebra mussels, dead or alive. Boaters are required to drain all water from their boat and onboard receptacles before leaving or approaching a waterbody to prevent the transfer of invasive species.

Please clean, drain, and dry your boat to help prevent the spread of these mussels and other aquatic invasive species!

Boat Ramp sign about aquatic invasives
Boat Ramp Stencil, Box Canyon


The U.S. has been invaded by two species of freshwater mussels: the zebra mussel (Dreissena polymorpha) and the quagga mussel (D. bugensis). Both are freshwater, bivalve mollusks that have a small, triangular shaped shell. Zebra and quagga mussels are Eurasian species that are not native to North America. Since their introduction, conservation-oriented bureaus, such as the National Park Service, have attempted to protect unaffected lakes from invasion and to slow the spread of mussels to new areas. A prevention program specifically targeting zebra and quagga mussels (ZQM) has been in place at Amistad national recreation Area since 2014, beginning with public outreach and education as the first step in the collective efforts to prevent the introduction of Dreissena mussels.The park has brochures in both English and Spanish that highlight the threat of zebra and quagga mussels. Park staff give presentations to the public, especially at fishing tournament meetings. The park also installed zebra and quagga mussel information stencils and signs in 2015 and 2016.
Person doing TOW Sampling
Amistad intern doing Tow Sampling


Early detection is one of the most important steps to initiate containment activities, which will help prevent the spread of invasive mussels to other water bodies. Resource Management staff have settlement samplers which are inspected monthly at docks and deep water areas adjacent to the boat ramps and Amistad Dam. In addition to the settlement samplers, park staff collects water samples to be tested for zebra and quagga mussel veligers (microscopic larvae). Vertical plankton tows are used to collect samples for analysis using Cross Polarized Light Microscopy (CPL) and/or quantitative Polymerase Chain Reaction (q-PCR) analysis at independent laboratories. Water sampling efforts have been concentrated near marinas, boat launches, and Amistad Dam.
Boat inspection with K9
Boat inspection


Amistad National Recreation Area launched a watercraft inspection program in 2015. The goals of the program include inspecting incoming boats for zebra and quagga mussels, educating boaters about the risks of invasion, notifying boaters of recent regulations, and gathering information relevant to zebra and quagga mussel spread from boaters (i.e. how well they clean their vessel, how often they visit infested/suspect lakes, etc.).

Lake Amistad at Amistad National Recreation Area has 5 major boat ramps that are open to the public and selected for inspections – Box Canyon, Southwinds Marina, Diablo East, Black Brush, and Rough Canyon. Inspectors stop incoming boats for a survey and a brief entrance inspection to look for mussels. If a boat is exceptionally dirty or has visited an infected/suspect lake in the last 30 days without decontamination, it is deemed “high risk” and is given a more rigorous search. Boaters that are leaving the lake are also surveyed and are reminded to drain their boats. From the beginning of the program in 2015 until May 2022, the park has inspected 10,000 boats. At times, the park also uses specially trained dogs to inspect for invasive mussels. The park has completed 1,391 inspections with over 261.9 working hours (March 11th to May 15th, 2021). Of those 1,391 inspections, 71 were high risk inspections (about 5.1%). Boaters came from 61 different waterbodies, and 18 of those waters were positive or infested with ZQM.

Twenty-four Texas lakes across five river basins can be currently (March 2021) classified as "infested" by Texas Parks and Wildlife with zebra mussels, meaning that the water body has an established, reproducing population.

An Invasive Mussel status map and full list of Texas lakes can be found on the TPWD website:

More about Lake Amistad's status can be found at

Last updated: July 29, 2022

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Del Rio, TX 78840


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