The highest concentrations of PCBs in the Housatonic River are found from the site of the GE plant in Pittsfield to Woods Pond in Lenox, Massachusetts, where they have been measured up to 140 mg/kg (140 ppm). About 50% of all the PCBs in the river are estimated to be retained in the sediment behind Woods Pond dam. This is estimated to be about 11,000 pounds of PCBs. Birds and fish who live in and around the river contain significant levels of PCBs.