Harbor dredging could stir up PCB-contaminated sediments

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Capital News Service
LANSING – Dredging may be a solution to part of the Great Lakes low water problem, but it can also lead to contaminated sediments re-merging into the water, experts warn.
A new law provides an additional $20.9 million for 58 emergency harbor dredging projects this year to help recreational and commercial boaters operate in low water levels.
The most common contaminant in the bottom of the Great Lakes is polychlorinated biphenyls, also known as PCBs, according to the Department of Natural Resources.

PCBs got into the water because of automotive industries near the lakes, said Andy Buchsbaum, director of the Great Lakes office of the National Wildlife Federation in Ann Arbor.
“A lot of PCB-laced oil was used by the automobile industry before it was banned and “leaked into the ground and ultimately found its way into the Great Lakes,” he said.
People who eat fish contaminated with PCBs and arsenic are at a high risk of cancer and other organ damage, but the largest negative effect these chemicals have is on reproductive health, Buchsbaum said because the chemicals “can impair the development of the fetus in pregnant women.”
When dredging moves contaminated sediments, chemicals are exposed. They can be harmful to wildlife and people who enter the water, said Kim Fish, assistant chief of the Water Resources Division at the Department of Environmental Quality (DEQ).
“In areas where we know we have contamination that is impacting wildlife and water quality, removal of that sediment is usually a good thing overall,” said Fish, but the department also needs to consider where to place the contaminated material and ensure it doesn’t spread the contamination.
Dredging exposes older sediment that is more contaminated than the sediment on top of it, she said. Those older sediments were contaminated prior to 1972 when there were few or no regulations on what could be discharged into the lakes.
PCBs affect fish as well when stirred up from dredging, said Joe Bohr, a DEQ aquatic biology specialist.
Carp and channel catfish tend to accumulate the highest amounts of PCBs, he said.
“With carp, they live on the bottom and they stir up the sediments – it’s similar with catfish,” he said. “Both of them tend to be fatty and these contaminants accumulate in the fat.”
Bohr said top predator fishes are at risk too when eating carp and channel catfish.
Fish said that as lakes Erie, Ontario and Superior reach all-time low water levels, there will calls for more dredging, there as well.
“This has been a several-year trend of lake levels declining. Primarily we are not getting a lot of ice cover in the winter on any of the lakes, which allows evaporation to occur all winter long,” she said.
Fish said another reason water levels are low is because snowfall has declined in northern areas of Michigan and parts of Canada. Snowfall maintains water levels when melted, or when snow goes directly into the lakes.
At the federal level, an additional $4 million more will be provided to fund dredging this year compared to last year, said Michael O’Bryan, chief of engineering and technical services at the U.S. Army Corps of Engineers Detroit district.
“Our needs are out there for more money. There is a significant increase in need for dredging funds in the Great Lakes area,” O’Bryan said.
O’Bryan said the Army Corps in the Great Lakes region needs about $40 million each year to keep up with dredging needs for commercial vessels.
Max King writes for Great Lakes Echo.
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