Upwelling Reduces Chlorine Effectiveness

From May, 1997 (Update #30)

Wisconsin Electric Power Company (WEPCO) Senior Results Technician John Babinec recently talked with ZMU about his company's difficulties using chlorine to treat for zebra mussels. Babinec reported WEPCO continues to use intermittent chlorination to reduce microbe-induced corrosion, but it has been insufficient in controlling zebra mussels in three Lake Michigan power plants. "In our experience at temperatures less than 60 F the effectiveness of chlorine really drops off," Babinec noted. Since WEPCO's Lake Michigan power plants are located on the western shore, frequent summer upwellings occur, bringing cold water - well below 60 F - into power plant intakes. "We also always seem to have translocators (adult mussels) entering our power plants, and intermittent chlorination doesn't seem to bother them either," said Babinec. He also said that in his experience, continuous chlorination isn't reliable because "sodium hypochlorite systems can be difficult to keep continuously online for four to five weeks, thereby giving the mussels some breathing room." As a result, Babinec reported that this year WEPCO plans to try different treatments at the two power plants currently using continuous chlorination, possibly a commercial molluscide at one power plant and chlorine dioxide the other. WEPCO is also considering the use of a copper ion generator. He said the advantage of chlorine dioxide over chlorine is that zebra mussels don't detect chlorine dioxide, and it is much more effective at lower water temperatures. This makes it possible to treat for zebra mussels in the fall, "after the mussel season is over," he said. For further information contact John Babinec at (414) 221-2452.

ID: 199705-8.

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.