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Zebra Mussels


Zebra MusselsTaste in the Water 
Every year the algae in the lake go through cycles with periods of peak growth in early spring, mid-summer and again in late fall. This causes an unpleasant (but harmless) taste in the water, described as weedy or musty. In most cases, routine water treatment with powdered activated carbon (PAC) removes this taste. PAC is a powdered version of the carbon used in home and commercial water purification filters. In recent summers, algae have been unusually prolific. The abundance of algae has been linked to the introduction of the zebra mussel into Lake Michigan. 

This mollusk is a living water filter that is native to Europe. As it feeds it removes particles from the water. The feeding of billions of zebra mussels has increased sunlight penetration that promotes growth of algae. When easterly winds prevail, these algae accumulate in the relatively shallow water in the vicinity of our intake pipes as well as those of all nearby water treatment plants along the North Shore. Despite increased PAC, the algae flavor is still detectable. These conditions can occur from July through early October. 

Minimizing Impact
Your City water plant personnel are doing everything possible to minimize the impact of these algae on the flavor of your drinking water. Should you notice this change, you can be confident that the water is perfectly safe to use. The taste of the water will return to normal soon after the wind direction changes. Meanwhile, the flavor of the water can be improved by keeping it in an open pitcher in the refrigerator. 

Contact Information
For more information on Zebra Mussels, visit the U.S Fish and Wildlife Service website, or contact the Water Plant at or 847.433.4355.