In the Great Lakes, the clearer water produced by zebra and quagga mussels allows sunshine to reach deeper into the lake than it would otherwise, encouraging the bloom of new species of algae; in fact, many local residents met the zebra mussel through a distasteful change in their drinking water. Before water suppliers changed their treatment regimes to deal with the algae growth, “the water had an organic taste, like an infusion of lawn clippings,” says Paul Hebert. “Imagine a grass shake.”

Steve Yancho, chief of natural resources for Sleeping Bear Dunes National Lakeshore, 35 miles of still-scenic beaches and sand mountains on Lake Michigan, remembers when visitors started complaining about large mats of sewage — at times bigger than a car — floating near the beach. The mats smelled revolting, and their texture was even worse. “We went out to grab some samples of the stuff with a boat hook,” says Yancho, “and it was like we were passing the hook through warm petroleum jelly.”

When park staff could bear to get closer, they realized the gunk had come not from a passing ship but from the bottom of the lake. It was the remnants of algae beds — fostered by the extra light and fertilized by mussel waste — that had died and decayed below the surface.

Scientists are still trying to understand the extent of the biological mischief caused by zebra and quagga mussels. In the Great Lakes, the mussels changed the migration patterns of ducks, some of which now snack on mussels all winter rather than fly south. (Zebra and quagga mussels have no North American predators capable of controlling their spread, but ducks and some species of fish, including the invasive round goby, do eat them.) Die-offs of loons and other birds — including 180 loon casualties at the Sleeping Bear lakeshore last summer — are blamed on the rare type E botulism, probably nurtured in the oxygen-poor conditions caused by rotting algae and mussel waste. The mussels’ filtering prowess can then concentrate the botulism toxin — and countless other contaminants — in their tissues and wastes, likely opening a new route for contamination in the Great Lakes food web.

The human costs are direct and enduring. “Anyone with a pipe in the water has reason to worry,” says Charles Ramcharan, an aquatic ecologist at Laurentian University in Ontario. In late 1989 and early 1990, the water supply for the Michigan town of Monroe was interrupted three times — once for more than two days — when mussels, drawn to the municipal water intakes by the flow of water and nutrients, mobbed the structures inside and out. Throughout the Great Lakes, power plants have fought off infestations of their cooling water systems, and in 1991, besieged Monroe hosed and vacuumed 30 tons of mussels out of a single water-intake structure.

Municipalities and industries along the Great Lakes have tried to defend their equipment with tactics ranging from electric currents to anti-mussel paint, but most now protect their intakes by installing feed lines for chlorine or potassium permanganate, which kill larvae and settling adult mussels. The horrifying initial costs have abated somewhat, but ongoing maintenance is required. Charles O’Neill Jr., an invasive-species specialist with New York Sea Grant, a university-based research and education program, estimates that zebra and quagga mussels have cost the region between $1 and $1.5 billion.

 

Baldwin has never fished in Lake Mead — he prefers to fly-fish the mountain streams of Colorado — but he loves the lake nevertheless, and often makes the 10-mile trip to the Las Vegas Boat Harbor from his home in Henderson.

“I go out in the middle of the lake, shut my boat off, and sit back and relax,” he says. “Or maybe I’ll get out on the beach, go climb in the hills. That’s how I get away from the rest of the world, let it go on by.”

The prospect of the lake’s degradation — and the associated risk to the city of Las Vegas, which gets about 90 percent of its drinking water from the lake — kept Baldwin interested in zebra mussels. His attention is notable, considering that his career has included stints as a rancher, hunting guide, design engineer, and, most recently, slots floorman at the Rio in Las Vegas. “Every time it gets routine, it’s time to change,” he says. “This never gets routine.”

Though Baldwin likes to insist on his scientific illiteracy, he learned enough mussel biology to deliver a forceful stump speech about the species and took his message into state and federal offices. In some quarters, his cause was a difficult sell: With plenty of immediate crises to worry about, public agencies had little time or money to spare for a theoretical problem, even one as reality-based as the zebra mussel. The Bureau of Reclama-tion, for example, funded an extensive zebra mussel monitoring program at its Western reservoirs for several years in the early 1990s, only to abandon the effort when the threat failed to materialize.