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Pipe-clogging mussel thriving in Lake Pleasant

Quagga mussels, a menacing mollusk, have been found at multiple sites at Lake Pleasant, posing a threat to the aquatic ecosystem, according to Arizona wildlife officials.

The discovery of the tiny mussels, about the size of a thumbnail, has spurred a request to boaters, anglers and other Lake Pleasant recreation users to help prevent the menace from spreading.

“We suspected it was just a matter of time before quagga mussels became established in Lake Pleasant, but we hoped it wouldn’t happen so soon,” said Larry Riley, a fisheries biologist for the Arizona Game & Fish Department.

The pesky invaders pose no health risk to the drinking-water supply, but the aquatic hitchhikers can multiply quickly and clog pipes, pumps and other equipment, officials said.

They have issued an advisory urging boaters and anglers to take precautions not only at Lake Pleasant, but also at other waterways throughout the state where quagga mussels can possibly spread.

Before leaving a waterway, they should clean the hull of all boats, removing all plant and animal materials.

The first hint of trouble came in February with an announcement that a quagga mussel had been found attached to a boat at Lake Pleasant.

Now, state officials have confirmed that the menacing mollusks have invaded the popular recreation site.

On Dec. 17, small adult mussels were collected from a dry-docked boat that had been moored at the lake, according to Rory Aikens, a spokesman for Game & Fish.

A team of agency biologists also found mussels at the southern end of the lake from boat slips at the Lake Harbor Marina, the Pleasant Harbor Marina boat launch and the 10-lane boat ramp courtesy dock, Aikens said.

The aquatic hitchhikers, which have caused millions of dollars in damage in the Great Lakes region of the United States, were first discovered at Lake Mead, which straddles Arizona and Nevada, in January of this year, he said.

Since then they have been confirmed at Lake Powell and a Central Arizona Project canal in Scottsdale, he said.

Mussel clusters pose no known health risks, but there is no known way for safe eradication of quagga clusters.

The inedible shellfish can multiply quickly and clog water intakes and pipes, costing millions of dollars to fix. In lakes and reservoirs, they can rob other aquatic life of food and oxygen, disrupting entire ecosystems.

Riley, the fisheries biologist for Game & Fish, said a single quagga mussel can produce 30,000 to 40,000 fertilized eggs in a single breeding cycle.

The primary method of dispersal is through human-related activities, such a hauling a boat from one lake to another waterway with adult mussels hitching a ride on the hull, officials said.

That’s why Arizona officials are encouraging the following precautions:

• Drain the water from boat motor and bilge before leaving the lake area.

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

• Inspect vessel and trailer, removing mussels, but also feel for any rough or gritty spots on the hull. These may be young mussels.

• Clean and wash trailer, truck of 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.

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