PCBs were designed NOT to break down. The river looks better and cleaner. When it comes to PCBs, the river is not better. The Clean Water Act has required improvements such as sewage treatment facilities and control of other pollutants from industrial sources, but PCBs continue to leak into the river, and have not been cleaned up. Controlling sources of PCBs into the river will solve the problem.
Source control is only part of the solution.
PCBs are escaping from river sediment and must be cleaned up. The PCBs buried in sediment on the river bottom are better left alone - dredging will stir up PCBs into the river. PCBs are not being buried by clean sediments. Of the estimated 1.3 million pounds of PCBs dumped by GE into the river, about 200,000 pounds remain in upper river sediments. Currents, especially flooding, boats, and bottom dwelling animals continually stir up sediments so that 500 pounds of PCBs wash over the Troy dam annually.