The United States and Canada signed the Great Lakes Water Quality Agreement in 1972. In 1978, the Agreement was expanded to cover pollution from toxic chemicals. Since 1973 the Great Lakes Water Quality Board has identified specific areas such as harbors, river mouths, and connecting channels as geographic areas of concern. Now the major problem in the majority of these areas is in-place polluted sediments. The Water Quality Board instituted a new ranking system for these areas in 1985. The purpose of the new system is to encourage progress and to allow the Board to report the status of investigatory and remedial activities accurately. The United States and Canada have banned production and use of certain toxic compounds such as DDT, dieldrin, and PCB's. The concentrations of these chemicals in fish have decreased over the last several years. Now the concentrations seem to be leveling-off, probably due to the continuing reservoir in the sediments. The highest concentrations of PCB's, up to 520,000 ppm, are found in Waukegan Harbor. The design of the proposed remedial action, under the United States Superfund authority, has been completed for Waukegan.