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Tue, May 11

Quagga mussel found near Phoenix

The quagga mussel invasion in Arizona has now advanced from the Colorado River lakes to the state's interior, and wildlife officials are seeking the public's help to fight this advancing menace.

A single adult quagga mussel measuring 15 mm in diameter was found on a sampling device in the Central Arizona Project aqueduct in north Scottsdale. The adult quagga mussel was discovered on a concrete tile sampling device placed in the aqueduct to monitor aquatic insects. The mussel was found at approximately mile post 179 just east of the Loop 101 bridge over the aqueduct in north Scottsdale.

"Finding just one mussel may not seem like much," said Larry Riley, a fisheries biologist with the Arizona Game and Fish Department. "But that single quagga is probably the tip of the iceberg - where there is one, there are bound to be others."

Riley pointed out that a single quagga mussel can produce 30,000 to 40,000 fertilized eggs in a single breeding cycle, and one adult female quagga can release up to a million eggs in a single year. It is clear that these larvae, or very young quagga mussels, flow toward central Arizona with water from the Colorado River. That puts them in direct proximity to central Arizona reservoirs.

New test results of water samples collected from Lake Powell do not indicate the presence of microscopic quagga or zebra mussel larvae. The water samples were analyzed using a microscopic method by the Center for Lakes and Reservoirs at Portland State University and by National Park Service biologists at Glen Canyon National Recreation Area.

Previous water samples analyzed by a Bureau of Reclamation laboratory using the microscopic method indicated the presence of quagga or zebra mussel larvae. The Bureau of Reclamation laboratory confirmed the presence of these mussels using DNA fingerprint technology.

"Given the uncertainty of this situation, we do not know whether a reproducing population of quagga or zebra mussels has become established in Lake Powell," said Kitty Roberts, superintendent of Glen Canyon National Recreation Area. "It is critical that boaters remember that our quagga and zebra mussel prevention program remains in effect. All boats coming from areas infested with quagga or zebra mussels must be properly cleaned or decontaminated before they may launch on Lake Powell."

Since initially detecting the presence of microscopic mussels in early August, the National Park Service has made a concerted effort to search for adult mussels. Divers have inspected more than 500 boats at the Wahweap Marina as well as underwater cables and concrete blocks. Glen Canyon's underwater remote operated vehicle has searched several deep water sites below the Wahweap Marina. So far, no mussels have been found.

To prevent quagga mussels or any other aquatic nuisance species from being spread, boaters should thoroughly wash their boats and trailers after they leave a 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.

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