Origin: Native of Eurasia
Impact: Zebra and quagga mussels are highly invasive, small freshwater mussels that multiply rapidly and can cause tremendous environmental and economic damage. Their larvae are microscopic, and the adults are usually less than 1 1/2 inches long. Zebra and quagga mussels are usually found in large clusters and usually have a zebra-like striped pattern on their shells. Zebra mussels will lie flat on a smooth surface on their hinge side, unlike quagga and native mussels. Once invasive mussels become established in a water body, they are impossible to eradicate with the technology currently available.
The spread of invasive mussels: Originally from the Balkans, Poland and the former Soviet Union, zebra and quagga mussels are firmly established in Europe and have invaded much of the U.S. In 2009, the first adult zebra mussel in Texas waters was confirmed in Lake Texoma. Zebra mussels have since spread rapidly from the Red River basin to the Trinity, Brazos, Colorado, Guadalupe, and San Antonio river basins. Quagga mussel larvae were confirmed in 2021 in Lake Amistad in the Rio Grande basin
Thirty Texas lakes across five river basins can be currently (August 2022) classified as "infested" with zebra mussels, meaning that the water body has an established, reproducing population: Austin, Belton, Bridgeport, Brownwood, Canyon, Dean Gilbert (a 45-acre Community Fishing Lake in Sherman), Diversion (private lake downstream of Medina Lake), Eagle Mountain, Georgetown, Granger, Grapevine, Inks, Lady Bird, Lewisville, Livingston, Lyndon B. Johnson, Marble Falls, Medina, O.H. Ivie, Pflugerville, Placid, Randell (access for Denison residents only), Ray Roberts, Richland Chambers, Stillhouse Hollow, Texoma, Travis, Walter E. Long, and Worth. Lakes where invasive mussels or their larvae have been detected on more than one occasion but so far there is no evidence of reproducing population are classied as "positive": Lakes Dunlap, Fishing Hole (a small lake connected to the Trinity River below Lake Lewisville), Lavon, and McQueeney as well as river reaches downstream of infested lakes on the Colorado, Guadalupe, Lampasas, Leon, Little, Red, and Trinity rivers. Lake Amistad in the Rio Grande basin is classified as "positive" for quagga mussels. Zebra mussels or their larvae have been found once in Lake Ray Hubbard, classifying this water body as "suspect". (See map) Several other lakes are considered "Inconclusive" due to recent DNA-only detections.
Experts fear they could spread to many other water bodies in Texas; biologists with Texas Parks and Wildlife Department and partners are monitoring many high-risk water bodies in Texas for the presence of invasive mussels.
If you have spotted Dreissena polymorpha & D. bugensis (Zebra and Quagga Mussels), use this report form to send an email to the appropriate authorities.