Scale of the Restoration Challenge
Vast deposits of pollutants lie within contaminated sediment, threatening for decades to come the health of Great Lakes fish and wildlife and humans. Remediating contamination remains a major challenge requiring significant up-front investments.
Contaminated sediment often does not lie in stable, easily identified and relatively easy-to-cleanup "hot spots". Sediment containing contaminants are often poorly controlled, unstable systems containing large volumes of moderately contaminated material.10 Contaminated sediment in Areas of Concern may be viewed as only a local problem. If they disperse, however, the contaminants can also affect the offshore regions and open waters of the Great Lakes, making remediation extremely difficult, and their toxic effects remain. Polluters responsible for the original contamination often no longer exist. Where polluters do exist, litigation often prolongs remediation. The Parties must take action more swiftly to prevent the inevitable and irreversible dispersal of contaminants.
Since existing programs have been insufficient for clean-up, governments must allocate adequate funds to clean up contaminated sediment and remove the threat to human health before sediment is too dispersed to remediate. In those cases where perpetrators can be found, some means must follow by which they pay for the problems they have caused. The Commission strongly recommends that the Parties develop strategies for prioritizing sites for remediation, and move forthrightly ahead.
To date, the magnitude of the contaminated sediment problem in Areas of Concern and its relationship to contamination of open lake waters remains poorly quantified. Sediment contaminated with PCBs and mercury is of particular concern.11 Natural degradation of highly chlorinated PCBs is limited and occurs very slowly.12
Preliminary estimates of PCBs in the sediment of lakes Superior, Michigan and
Ontario are 3,300 kg, 87,000 kg and 115,000 kg, respectively.13 The
Lake Michigan estimate does not include the quantities in Green Bay, which have
been calculated separately at 68,000 kg. Large quantities of contaminated sediment
at sites such as the Fox River and Lower Green Bay can also serve as indirect
sources of PCBs molecules of PCBs can be transferred first to water, then
into the air (volatilized) and back into the open lake by prevailing winds.14
The relative significance of PCB loads contributed by the atmospheric pathway
varies for each lake basin. Estimates for Lake Michigan indicate that 3,200
kg per year reach the lake through the air.15
Sediment remediation remains a large-scale, high-cost problem requiring a strategic long-term solution. While the magnitude of the problem is greater in the United States than in Canada, using the most modest estimates, it would cost billions of dollars for thorough remediation.
Large-scale remediation efforts signal a commitment to protect the health of present and future generations and to restore the integrity of the Great Lakes. Reducing the body burdens of persistent toxic substances in fish populations will achieve the goal of protecting human health from this consumption pathway and will assist in the recovery of fish and wildlife populations. Based on positive restoration results in areas such as Gill Creek (a tributary of the Niagara River), Black River and Waukegan Harbor, remedial actions can be expected to stimulate improvements in ecosystem health in comparable Areas of Concern.