September 2007

Invasive Mussels Detected In Lake Powell

Boaters Asked To Inspect Their Vessels For Mussels

PAGE, Ariz. – 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.

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.”

Samples Being Analyzed

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.

Prevention Program Remains In Place

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: Further information about quagga and zebra mussels and how to prevent their spread is available online at, www.protect, and

 Search For Quagga Or Zebra Mussels Continues

The search for adult quagga or zebra mussels is continuing at
Glen Canyon National Recreation Area.  Since Aug. 10, divers have been searching the Wahweap Marina area for visible quagga or zebra mussels.

They have been carefully inspecting boats, cables, and dock structures.  As
of today, approximately 500 boats in the Wahweap Marina have been thoroughly examined for mussels.  So far, no visible quagga or zebra mussels have been found.

Additional sampling for microscopic larval mussels is also continuing in
the Wahweap Marina area in hopes of identifying a “hot spot” of activity. Samples were also collected this week by the Utah Division of Wildlife Resources at Bullfrog and Halls Crossing Marinas, in the San Juan Arm of Lake Powell, the Rincon, Padre Bay, and Good Hope Bay.

Most of the samples are being sent to a Bureau of Reclamation laboratory in
Denver for processing.  In addition, the National Park Service has upgraded its
microscopic equipment at the Wahweap laboratory, which allows some samples
to be examined locally.

On Aug. 15, a boat with quagga mussels attached to it arrived at Glen Canyon National Recreation Area.  The boat had come from Lake Mead, where it had been moored since April. 

The boat was fully decontaminated by ARAMARK at the new Wahweap decontamination station before it was permitted to launch into Lake Powell.   This was the second boat this year that had come to Glen Canyon with quagga mussels visibly attached.

Superintendent Kitty Roberts reminds visitors that, “We are still actively
trying to prevent quagga or zebra mussels from infesting Lake Powell.  At the same time, we are mounting a major search to determine if an established population exists in the Wahweap area, while expanding our sampling to determine if mussel larvae are present in other parts of the lake.”

For more information and answers to frequently asked questions on this topic, visit