The introduction of zebra mussels, Dreissena polymorpha, into North American fresh waters in 1986 and quagga mussels, Dreissena bugensis, in 1990 from Europe and their spread through inland waters have resulted in a major economic impact to raw-water-dependent infrastructures, including power generation facilities, municipalities, and private industry. Because of the ability of these tiny mussels to quickly colonize hard substrates in high densities (e.g., tens of thousands per square meter), they have become a major macrofouler within North American freshwater conduits, causing damage and increased operating expenses worth hundreds of millions of dollars.
Zebra mussels have caused expensive problems, blocking pipes that deliver drinking and process water to cities and factories and cooling water to power plants; attaching in enormous numbers to ship and boat hulls, marine structures and navigational buoys; and covering beaches with sharp-edged mussel shells and rotting mussel flesh. In the United States, congressional researchers estimated the mussel cost the power industry alone $3.1 billion in the 1993-1999 period, with its impact on industries, businesses, and communities over $5 billion (New York Sea Grant 1994a). In Canada, Ontario Hydro has reported zebra mussel impacts of $376,000 annually per generating station (New York Sea Grant 1994b).
The zebra mussel, though small in size, has become the most troublesome freshwater biofouling organism in North America. Once a single mussel is in place, others settle on or around it. The colonization increases until a pipe or an opening is partially or completely blocked. A piece of equipment may become fouled or so encrusted with mussels that it becomes unusable, and costly control measures must be implemented. Even if mussels are killed by a chemical or thermal control technique, the shells and decaying tissues may remain behind causing additional problems. Prevention is the best weapon against initial infestation, for once a water body is infested with a zebra mussel population, there is virtually no eliminating it.
The Western U.S. will be the next invasion arena for Zebra and Quagga Mussels with severe economic impact to industry, ranching, irrigation, and municipalities.
Water rights issues are predicted to intensify. See the distribution link at left.