National Park Service makes an ‘unfortunate’ discovery at Southwest Texas lake: a new invasive mussel

Quagga mussel in Amistad is the first discovery of an invasive mussel species in the Rio Grande basin

The quagga mussel discovery was made by National Park Service staff at the International Amistad Reservoir near Del Rio. (Amy Benson USGS/Google Maps)

The quagga mussel — a more harmful close relative of the zebra mussel that’s already invaded 33 state lakes — was detected in Texas for the first time.

The Texas Parks and Wildlife Department said quagga mussel larvae were discovered by National Park Service staff on four occasions at the International Amistad Reservoir. The lake is located near Del Rio and straddles the U.S.-Mexico border.

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While no juvenile or adult mussels were located — only larvae — TPWD said this is the time to prevent spread and the development of a fully established population.

Zebra mussels are known to damage boats, hurt aquatic life and clog pipes, but TPWD said quagga mussels are more harmful.

“This detection of invasive quagga mussels is a very unfortunate first for Texas,” Monica McGarrity, TPWD senior scientist for Aquatic Invasive Species, said in a news release. “Quagga mussels can inhabit greater depths and are also able to settle on soft substrates like mud or sand in addition to hard surfaces like rock or infrastructure—unlike zebra mussels—meaning they can colonize more of the lake.”

“Quagga mussels are very prolific and can form larger populations that can have greater effects on the lake ecosystem overall, especially in deep lakes.”

It’s also the first discovery of an invasive mussel species in the Rio Grande basin, TPWD said.

NPS regularly inspects Amistad lake’s shorelines and docks for invasive mussels, even bringing in mussel detection dogs, according to TPWD.

McGarrity added that lakes with zebra mussels are already at risk for the introduction of the quagga mussel.

So far in the San Antonio area, zebra mussels have infested Buchanan, Canyon, Inks, Lyndon B. Johnson, Marble Falls, Medina and Placid Lakes. Zebra mussels have also been detected at Dunlap and McQueeney Lakes.

Boaters can help stop the spread by removing debris from their boats, draining water and allowing gear to dry out.

According to, boaters could face a $500 fine for the transportation or possession of invasive mussels if they do not clean, drain and dry their boats.

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About the Author:

Rebecca Salinas has worked in digital news for more than 10 years and joined KSAT in 2019. She reports on a variety of topics for KSAT 12 News.