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Thu, Jan. 28

Invasive mussel species makes first appearance at Lake Mead

An aquatic invasion that officials in Arizona have been dreading is now underway: A harmful species of mollusks that disrupts ecosystems and can spread through entire river systems has been discovered in Lake Mead along the Arizona-Nevada border.

The Dreissena species of mussels, which includes two closely related types ­ the zebra and quagga ­ can clog water intake pipes, negatively affect hydroelectric power operations, ruin boat engines and impact water delivery systems.

These small, invasive mussels, which originally came from eastern Europe, have been causing multi-million dollar problems in the Great Lakes and the Mississippi River basin.

Lake Mead is 1,000 miles farther west than any previously known colonies of these mollusk invaders.

Thanks to advance preparations and training on aquatic nuisance species, these invasive freshwater mussels were first spotted Jan. 6 at the Las Vegas Boat Harbor at the southern end of Lake Mead by an alert marina employee. Since that time, they have been confirmed to exist in other locations in the Lake Mead ecosystem.

At this time, the infestation (at least for the detectable adult population) appears to be limited to the Boulder Basin area of Lake Mead.

Divers from the National Park Service, Arizona Game and Fish Department and U.S. Fish and Wildlife Service have inspected and found no evidence of adult invasive mussels at the following locations:

• Temple Bar marina facilities (Arizona side of Lake Mead).

• Cottonwood Cove marina facilities (Nevada side of Lake Mohave).

• Willow Beach marina facilities (Arizona side of Lake Mohave).

• Willow Beach Fish Hatchery (operated by U.S. Fish and Wildlife Service).

Additional evaluations have been conducted at Callville Bay, Echo Bay, Overton Beach and Hoover Dam.

"These invasive mussels are a serious threat to water delivery, recreation, hydro-power operations and fish and wildlife resources," said Larry Riley, fisheries chief for the Arizona Game and Fish Department. "These small mussels can reproduce and spread rapidly, and are often difficult to detect until they have become well established. A long list of agencies and organizations are cooperatively mobilizing to address this threat."

Riley says the first order of business is determining the existing spread of this invasive species, while at the same time taking all possible steps to deter or impede the future spread of these small, but prolific mussels.

Officials stressed that while various cooperators are investigating the extent of the threat and coming up with multiple ways to combat this invader, a critical element is getting the public involved.

"Guaranteed, we need the public ­ especially boaters and anglers ­ to help prevent the spread of this aquatic invader," Riley said.

These mussels can survive in a few inches of water in the bilge or livewell of a boat, can attach to boat trailers or even cling to the hulls of boats and other flat surfaces.

The juvenile form or larvae of this aquatic menace is microscopic and not visible to the eye.

Boaters (including personal watercraft, canoe, and kayak users) and anglers should take the following precautions to help by ensure their boats, vehicles, trailers, and other equipment do not become the means of infecting other waters:

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

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

• 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.

• 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.

• 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 exposed to infested waters.

Riley stressed that these invasive mollusks are just one of the aquatic nuisance species to be concerned about.

"Boaters, anglers and other water recreationists should really take routine precautions to avoid transporting any nuisance species. A lot of them are out there, such as golden algae or giant salvinia," he said. "A few precautions now will help us protect our waters for the future."

For additional information on this aquatic invader and others, visit the Game and Fish Department Web site at or

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