In the 1980s, the United States and Canada identified 43 highly degraded shoreline areas along the Great Lakes, including 26on the U.S. side and 17 in Canada, with five shared between the two countries. Known as “Areas of Concern� or “AOCs,� these areas are the focus of comprehensive cleanup efforts involving federal agencies,the Great Lakes states, municipalities and other partners. The most common problem affecting these toxic hotspots is contaminated sediment from past industrial practices.Today, 30 AOCs exist wholly in the U.S.or are shared with Canada.