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Mon, Sept. 21

Planning under way to combat infestation by invasive mussel

Following the discovery of a prolific species of invasive mussel at Lake Mead last month, experts here are working with other government agencies to prevent its spread.

According to park Public Affairs Officer Maureen Oltrogge, resource protection and Science Center staff are the primary divisions involved.

They are working with staffs from Lake Mead and Glen Canyon national recreation areas, the U.S. Geological Survey, the U.S. Fish and Wildlife Service and Arizona Game and Fish.

Oltrogge said that they are investigating to see if the mussels are present in the Colorado River and at Lake Powell. If the inspection turns up none, she said they will focus on a strategy of preventative education.

If mussels are found, actions to remove them will go through the scoping process under the National Environmental Policy Act (NEPA).

The quagga mussel, an invasive species commonly referred to as the zebra mussel, was detected in Lake Mead on Jan. 8.

The mussels were discovered in the Boulder Basin area of the lake, on an intake tower and spillway structure at Hoover Dam, downstream of the dam at Katherine Landing, and in Lake Havasu. Currently, Lake Powell and the Colorado River as it runs through Grand Canyon are believed to be free of mussels. However, quagga mussels pose a major threat to the canyon if they are introduced.

River users and recreational fisherman are the most likely vectors for moving the invasive mussel into the Colorado River in Grand Canyon through river rafts and gear used in infested areas.

Park officials expect to work out agreements on procedures by the end of this month, former park Superintendent Joe Alston said in a statement last week.

"Since quagga mussels were discovered in the western portion of Lake Mead, we have been working with many parties to develop procedures to prevent entry of the invasive mussels into Grand Canyon National Park," he said. "We are fortunate that the infestation to date appears to have not yet reached the eastern portion of Lake Mead, but because of the close proximity and potential for spread, we will be aggressive in our approach to prevent quagga mussels from entering the Colorado River in Grand Canyon."

Lake Powell began a proactive prevention program in 1999, regularly sampling the waters for evidence of the mussels. Since 2003, they have required free boat washes for those that had been in infested waters in the previous 30 days.

Quagga and zebra mussels are native to eastern European seas. They first appeared in Lake St. Clair in Michigan in 1988. They are believed to have been released two years earlier in a ballast discharge from an ocean vessel. Since that time, they have spread throughout the Great Lakes and Mississippi River basin. The Lake Mead infestation is 1,000 miles west of any known population and the first west of the Continental Divide.

They normally spread by attaching themselves to boats, which are launched in one lake and then later moved into a different lake. Both quagga and zebra mussels are microscopic in juvenile life stages, making them impossible to detect based solely on a visual inspection.

Zebra and quagga mussels release between 30,000 and 40,000 eggs each breeding cycle and a single mussel can produce as many as 1 million eggs a year. They attach themselves to hard objects and develop colonies that can grow into the billions. In the Great Lakes, they are reported to be as dense as 700,000 per square meter in some places.

According to a report to Congress, between 1993-1999, they cost the power industry $3.1 billion. Their overall economic impact is estimated at about $5 billion.

They also upset the ecosystem by consuming more than their share of organic matter and plankton out of the water. Each individual mussel can filter about one quart of water each day, so that a large population of quagga mussels can consume the food that should support the natural food chain in an aquatic system. This and other body functions of quagga mussels typically result in serious adverse effects to native aquatic life.

Currently, visitors can help keep Grand Canyon free of invasive mussels by:

When taking your equipment out of the water:

• Drain the water from your motor, live well, and bilge on land before leaving the immediate area of the lake.

• Completely inspect your vessel and trailer, removing any visible mussels, but also feel for any rough or gritty spots on the hull. These may be young mussels that can be hard to see.

Before driving out of the local community:

• Flush the motor and bilges with hot, soapy water or a 5 percent solution of household bleach.

• Wash the hull, equipment, bilge and any other exposed surface with hot, soapy water or use a 5 percent solution of household bleach.

• Clean and wash your trailer, truck or any other equipment that comes in contact with lake water. Mussels can live in small pockets anywhere water collects.

When you return home:

• Air-dry the boat and other equipment for at least five days before launching in any other waterway.

• Do not reuse bait once it has been in the water and allow all fishing tackle to air dry for five days before fishing in other lakes and streams.

Visit for more information about quagga mussels.

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