NSTAR is a utility company that provides retail electricity and natural gas to 1.4 million customers in eastern and central Massachusetts, including the Boston urban area. NSTAR was formed in 1999 by the merger of BEC Energy and Commonwealth Energy System and currently has the following operating units: Boston Edison Company, Cambridge Electric Light Company, Commonwealth Electric Company, and NSTAR Gas Company (formerly Commonwealth Gas and Cambridge Gas Company).   For more than 100 years, NSTAR Electric and Gas has been delivering safe and reliable electricity and natural gas to customers in Eastern, Central and Southeastern Massachusetts. NSTAR transmits and delivers electricity to 1.1 million electric customers in 81 communities and nearly 300,000 gas customers in 51 communities. NSTAR is an operating company of Northeast Utilities.   NSTAR has had its share of environmental mishaps, including nearly a dozen spills at its former Watertown, Massachusetts facility. The spills, most of which occurred during the 1980s, consisted of transformer oil, which contained PCBs in high concentrations (6,200 Parts Per million). These spills have contaminated nearby Sawins and Williams Pond, both of which are downgradient of the NSTAR facility, and possibly flowed into the Charles river, which is downstream of Sawins Pond. Many local activists lobbied for NSTAR to abide by state regulations and spend the $20-40 million required to perform a PCB remediation of the affected lands. By 1997 NSTAR was responsible for nearly 50 hazardous waste sites, and by 2006 all but 5 of these had been cleaned up.