Invasive mussels detected in Lake Powell

Boaters asked to inspect their vessels for mussels

Additional information: Quagga mussels threaten Utah

PAGE, AZ. - New test results indicate the presence of an extremely small number of individual, larval quagga or zebra mussels in Lake Powell. Two cooperative research and monitoring efforts, conducted on July 19 and 30 by the U.S. Geological Survey, the National Park Service, and the Utah Division of Wildlife Resources, detected three individual mussel larvae at the Wawheap Marina and near the Glen Canyon Dam.

Invasive mussels
Photo from U.S. Fish & Wildlife Service, La Crosse Fishery Resource Office

Dr. David Britton, an expert on quagga and zebra mussels for the U.S. Fish and Wildlife Service, said, "While the test results indicate the presence of individual larval quagga or zebra mussels in Lake Powell, much uncertainty remains. We do not know at this point if an established population is present. We also do not know for certain how quagga or zebra mussels will affect Lake Powell."

Five water samples were collected from Lake Powell and analyzed by a Bureau of Reclamation laboratory in Denver (see table below). The samples were analyzed using two different methods a microscopic technique and DNA fingerprint technology. Three of these samples did not indicate the presence of any quagga or zebra mussels. Two of the samples, collected at the Wahweap Marina and near the Glen Canyon Dam, indicated the presence of three individual larval mussels when tested with the microscopic method and DNA fingerprint technology. The testing methods cannot distinguish whether or not these are quagga mussels or zebra mussels, which are closely related.

"Additional samples have been collected from Lake Powell and are being analyzed for quagga and zebra mussels. In the coming weeks, more samples will be collected from various locations around the lake to determine if mussels are present in other areas," said Kitty Roberts, superintendent of Glen Canyon National Recreation Area.

The National Park Service, Utah Division of Wildlife Resources, Arizona Game and Fish Department, Bureau of Reclamation, and U.S. Fish and Wildlife Service have been closely working with each other to monitor the spread of quagga mussels since they were found in Lake Mead in January 2007.

The National Park Service's existing quagga and zebra mussel prevention program will remain in place. Boats that have been in water bodies with known quagga or zebra mussel infestations in the last 30 days will continue to be required to be decontaminated before entering Lake Powell. High pressure, hot water decontamination stations are available at all marinas within Glen Canyon National Recreation Area, including Wahweap, Antelope Point, Bullfrog, and Halls Crossing marinas.

As a preventative measure, the National Park Service will also begin requiring any boats that are slipped or moored in Lake Powell to receive a decontamination wash before they exit the park if they are being moved to a non-infested lake. In addition, people with boats in the marinas at Lake Powell are strongly encouraged to conduct a thorough inspection of their boat to look for quagga or zebra mussels which may be attached.

To prevent quagga mussels or any other aquatic nuisance species from being spread to other lakes, all visitors leaving Lake Powell or any other body of water should thoroughly wash their boats and trailers after they leave the lake. Bilges, wet wells, motors, and any other part of the boat that could hold water must be completely drained. Any other gear that has come into contact with the water such as waders or fishing equipment should also be washed. The boat and all gear should be allowed to thoroughly dry in the sun for at least five days before being used in another water body.

Detailed descriptions about how to clean your boat and equipment are available online at: www.wildlife.utah.gov/quagga/pdf/boat_inspection.pdf. Further information about quagga and zebra mussels and how to prevent their spread is available online at www.100thmeridian.org, www.protectyourwaters.net, and www.nps.gov/glca.

Quagga/Zebra Mussel test results as of Aug. 8, 2007
Sample dateLocationMicroscopic ResultsDNA fingerprint resultsVeligers detected
July 19, 2007Main Channel near Glen Canyon Dam (sample 1)PositivePositive1
July 19, 2007Main Channel near Glen Canyon Dam (sample 2)NegativeN/A*0
July 30, 2007Main Channel near Glen Canyon DamNegativeN/A*0
July 30, 2007Wahweap Marina, south side breakwaterPositivePositive2
July 30, 2007Antelope Point Marina Launch RampNegativeN/A*0
*Note: The DNA fingerprint method has not been done on these negative samples.