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A view of zebra mussels.
Zebra mussels can cluster together and clog water intake pipes.
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Zebra Mussel Biology
Zebra mussels are not native to Green Bay or the Great Lakes. They were accidentally introduced into the Great Lakes in the 1980s from the ballast water ships from Europe. The first Zebra mussels appeared in Green Bay in the 1990s. Since then, they have established large populations throughout Green Bay.
Zebra mussels attach to any type of solid surface underwater, including rocks, clams, boats, water intake pipes and even other Zebra mussels. Consequently, they have become quite a nuisance to swimmers, boaters, industries and water utilities with water intake pipes.
Zebra mussels feed by filtering material out of the water. In fact, each Zebra mussel filters about a quart of water per day! It is no wonder then that they are viewed by many scientists as being capable of causing changes in water quality in the Great Lakes.
Distribution of Zebra Mussels
Researchers from the University of Wisconsin, Green Bay, who study Zebra mussels in lower Green Bay have concluded that:
- Their distribution is quite patchy
- Densities are lower in the region near the mouth of the Fox River, and higher north of Long Tail Point and Point Sable.
- Densities are also higher on the east shore compared to areas on the west shore.
Effects of Zebra Mussels on Water Quality in Lower Green Bay
A recent analysis of water quality data from GBMSD's Ambient Water Quality Monitoring Program produced the following conclusions about the potential effects of Zebra mussels on water quality of lower Green Bay:
- Zebra mussels may be increasing water clarity slightly in lower Green Bay.
- A recently noted slight decline in the amount of suspended material in the water of lower Green Bay may be related to the filtering of Zebra mussels.
- Improvement in water quality as the result of Zebra mussels appears to be negligible within about 10 miles of the mouth of the Fox River and a bit more noticeable beyond that range.
- Overall, there was not a dramatic effect noted in the water quality data that could be attributed to Zebra mussels
- Consequently, Zebra mussels are not viewed as the solution to lower Green Bay's water pollution problems.
Zebra Mussels and the Green Bay Metropolitan Sewerage District
Industries located on the Fox River that have hot water intakes have had to install protective measures to prevent their intake pipes from becoming plugged with Zebra mussels. Since the Green Bay Metropolitan Sewerage District (GBMSD) water reclamation facility has a discharge pipe, not an intake pipe, it has no need to resort to such measures.
Zebra mussels cannot move against the current of the water reclamation facility's discharge. Consequently, they cannot plug the discharge pipe or negatively impact the operations of our water reclamation facility.
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