Mussels Muddy Water Taste

From January, 1995 (update #23)

CHICAGO, Ill. - A muddy taste produced by algae decay products and bacteria has cropped up in water supplied by several Great Lakes water utilities. Some water utility personnel are blaming the bad taste on zebra mussels. The taste problem occurred during the summer of 1993 and several times this year, according to John DeKam, superintendent of the Bay Metro Water Treatment Plant in Bay City, Mich. DeKam said the taste is often described as muddy or moldy; at times last year he received as many as 30 customer complaints a day. Utilities in Detroit, Windsor, Ont., and Alpena, Mich., have reported similar problems, according to DeKam. DeKam said that the development of the musty, moldy taste was associated with two chemicals: geosmin and 2-methylisoborneol. Both chemicals are considered harmless to human health but unpleasant tasting; people with sensitive palates can detect the flavors at levels as low as five parts per trillion. DeKam said that the bad taste developed at the Bay City Plant about the same time that high levels of actinomycetes bacteria appeared. Other water plant operators have blamed the bad-tasting chemicals on decaying benthic algae, which may have increased due to the presence of zebra mussels. DeKam said that potassium permanganate and activated carbon can be used to remove much of the offensive taste. But these treatments are not always quick, cheap nor completely effective. The Chicago Tribune reported that the Chicago Water Utility spent $3.6 million this year on 7.3 million pounds of activated carbon to treat the problem. According to the Tribune, prior to 1993 the water utility had never used more than 500,000 pounds of activated carbon per year, and in some years none at all. Seasonal taste and odor problems associated with geosmin and 2- methylisoborneol did not originate with the appearance of zebra mussels, DeKam said, although taste problems usually become apparent in the fall. Last year's outbreak at Bay City was unusual because it began in late June and continued through the summer. Wisconsin water utility operators have not, to ZMU's knowledge, reported this problem. In fact, Dave Ewig, superintendent of the Port Washington water utility, said that water quality was excellent all summer due to reduced turbidity. Ewig attributed the fine water quality to the presence of zebra mussels in the lake.

ID: 199501-5.

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.