LAKE PLEASANT – Hundreds of tiny quagga mussels clinging to a 43-foot boat provided proof that the pesky mollusks hadn’t gone anywhere over the winter, but state wildlife authorities wanted to make a bigger point Thursday.
Boats and their owners are all that stand between the quaggas and the rest of Arizona’s lakes.
“We need the public to help by not moving these guys around,” said Kevin Bergersen, a law-enforcement administrator for the Arizona Game and Fish Department. “The costs of letting them out are profound. Clean, drain and dry, and life will be good.”
That advice – cleaning a boat after removing it from a lake, draining it and allowing it to dry thoroughly – will figure prominently in a ramped-up publicity campaign aimed at containing the quaggas.
The thumbnail-size mollusks have so far infested Lake Pleasant, along with Lakes Mead, Mohave and Havasu on the lower Colorado River. Although the mussels pose no health risk to humans, they can clog pipes, jam machinery and begin to destroy parts of a lake’s ecosystem.
Water provider Salt River Project is pouring resources into the campaign in an effort to keep quaggas out of its six largest reservoirs on the Salt and Verde rivers. If the mussels find their way into those lakes, they could spread into water-treatment plants across Phoenix, distribution pipes and power plants.
Boats have become the focal point because they almost certainly brought the first mussels from the Great Lakes to Lake Mead and are a likely form of transport between lakes.
Although mussels can form crusts several inches thick on metal and concrete surfaces, the boat hauled out of Lake Pleasant on Thursday was not as obviously infested. Tiny quaggas clung to the drive shaft and the propellers, but a boat owner might mistake them for other debris that builds up underwater, Bergersen said.
“The average boater will look at this and say, ‘I don’t have a problem,’ ” Bergersen said. He scraped off a handful from the hull. “This is a problem. These guys will hang on if you don’t wash them off or let the boat dry.”
Quaggas can linger in damp conditions but can’t survive long once a surface dries completely.
Bergersen plucked a mussel shell from a plastic bucket that held hundreds more, all scraped Thursday morning from a boat in the nearby harbor.
He held it between his thumb and forefinger and pinched. It turned to dust.
“That’s what you want to see,” he said. “He’s done for. If you see this . . . ”
He pulled a small container from his pocket and pulled out something softer, slimier. He squeezed it and it oozed moisture. “You’ve got trouble. If you miss one of these when you clean, they’ll go to town the next time the boat goes in the water.”
Lesly Swanson, an environmental scientist for SRP, said it’s critical to prevent the spread of the mussels because it’s almost impossible to eradicate them once they settle in. SRP continues to monitor its lakes and so far has found quaggas only at a junction between an SRP canal and the Central Arizona Project Canal.