Studies Find Declining Levels Of PCB Contamination In Michigan Harbor

EPA studies find post-cleanup studies of the Manistique Harbor and River (Manistique, Mich.) show declining levels of polychlorinated biphenyl (PCB) contamination, the agency announced on April 11.

EPA oversaw a $48 million Superfund cleanup, which involved dredging and removal of 190,000 cubic yards of sediment from the harbor bottom. The sediment was contaminated by PCB discharges from industrial facilities from the 1950s through the 1980s. Dredging was completed in 2000.

EPA completed a study of sediment, surface water and fish in late 2004, with comprehensive data analysis performed during 2005. A second, smaller-scale sampling effort was performed in 2005, with the data analysis completed recently.

Results from the two studies show encouraging trends for ecological recovery of the harbor. At the completion of dredging in 2000, the average PCB level in shallow sediment was 7.7 parts per million (ppm). In contrast, the 2004 sampling showed the average PCB level had dropped below 1 ppm. EPA's pre-dredging cleanup goal was 10 ppm.

While the data results are positive, more research is needed to confirm the long-term recovery of the harbor. Michigan Department of Environmental Quality (MDEQ) fish consumption advisories remain in effect for Manistique Harbor.

Because harbor and river conditions can change over time due to water currents, erosion and development, small-scale sampling was also conducted during August and September 2005. The results of the 2005 sampling in the harbor "hot spots" found that PCB levels remained very close to the levels found in the 2004 sampling in those areas. Additional small-scale sampling is scheduled for 2006 and 2007. Another comprehensive analysis of site conditions is slated for 2008.

A fact sheet about the studies is at http://www.epa.gov/region5/sites/manistique.

In addition to the post-dredging monitoring, the Manistique River and Harbor is designated as a Great Lakes Area of Concern. EPA, MDEQ and a local public advisory committee are currently engaged in documenting the ecological recovery of Manistique and working toward the goal of delisting it as an area of concern.

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