Meanwhile, Up Around the Bend...

From September, 1996 (Update #28)

A handful of adult zebra mussels ranging in size from 10 mm to 40 mm were discovered last fall and early this year at three Northern States Power (NSP) plants on the Mississippi River, according to NSP biologist Ken Mueller. This is the farthest north on the river that industrial facilities have reported finding zebra mussels. Zebra mussels were found at the Highbridge Power Plant in St. Paul, Minn., during a routine maintenance inspection. Mussels were also discovered at the Red Wing Power Plant, Red Wing, Minn., during an inspection conducted specifically for zebra mussels, and three adult zebra mussels were found at the Prairie Island Power Plant (just upstream from Lock and Dam 3) in late January of this year. In all instances, the mussels were found in de-watered intake bays; a few solitary zebra mussels were attached to intake bay walls, traveling screens, shafts and sprockets. Mueller emphasized that mussels had never been found at these locations on substrate samplers monitored by NSP personnel. Mueller speculated that the mussels were translocators - they'd migrated into the systems as adults. At the Highbridge Plant, a bromination system used to control biofouling in the plant's service water system will be used to attempt to control veliger settlement. Mueller said that this treatment originally was not expected nor intended to control attachment of large mussels, including translocators, in the intake bays. A control treatment using a non-oxidizing biocide was planned for July to control attachment of those mussels, he said. Bromination equipment also has been installed and tested at the Red Wing plant; Mueller said a control treatment using either hot water or a non- oxidizing biocide was planned for August. At Prairie Island, a non-oxidizing biocide treatment was planned for early September, he said, while other plant systems will be thermally and/or chemically treated next spring. Mueller summed up his experience by saying that water-related industries along the Mississippi River may be relying too heavily on substrate samplers for early zebra mussel detection. Based on his experience Mueller said, "I recommend three things: (1) dewatering and close visual inspection are the best method for early detection, (2) substrate samplers are not dependable for determining zebra mussel arrival, and (3) preparing control strategies prior to infestation is critical."

Doug Jensen, Minnesota Sea Grant.

ID: 199609-12.

The Zebra Mussel Update was a 4- to 8-page quarterly national newsletter published by the University of Wisconsin Sea Grant Institute from May 1990 through May 1997. The ZMU documented the spread of the zebra mussel -- an exotic nuisance mussel -- through North America's freshwater environments, especially the Great Lakes, and on efforts to control it.