Z‐E‐B‐R‐A Spells Trouble for Treatment Operators

Zebra mussels gained a foothold in European freshwater harbors during the past 150 years, having gradually spread to that region from the Caspian Sea. Having established a foothold in the European bays, zebra mussels are believed to have been inadvertently taken aboard tankers bound for North America when the vessels drew in water to use as ballast. Zebra mussels cause damage both to man‐made and natural processes. The problems they create for water treatment operators result from the species' rapid rate of regeneration coupled with their ability to attach to almost any clean, hard surface and their tendency to form clumps. The zebras can easily clog submersed pipe openings. Other problems result from the weight of many thousands of mussels on a buoy or piece of equipment. There are several ways to fight zebra mussels, from scraping out clogged intakes to preventive chlorination, but both preventive and remedial actions can be expensive. Monitoring in areas currently affected or potentially threatened by zebra mussels is essential. Unfortunately, the zebra's appearance during the early stages of development closely resembles that of other mussels; false alarms have been sounded on more than one occasion.