NSTAR

NSTAR was formed in 1999 by the merger of BEC Energy and Commonwealth Energy System and had 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).

As a part of deregulation of the local electrical power industry, NSTAR has divested itself of all electric generation facilities, keeping only those elements of the business which remain regulated. NSTAR sold its interest in the Seabrook Station nuclear power plant to FPL Group in 2002.

On November 16, 2006, the company announced a 7.4% increase in its dividend to an annual rate of USD1.30 per common share from the previous USD1.21.

NSTAR has ownership of unregulated district energy and telecommunications businesses, including Medical Area Total Energy Plant, LLC. which produces electricity, steam and chilled water for sale to customers in the Longwood Medical Area of Boston.

Electric power distribution in the New England area is coordinated by ISO New England, a regional transmission organization.

In October 2010, Northeast Utilities and NSTAR announced they would merge, with the resulting company retaining the Northeast Utilities name. Under the terms of the transaction, NSTAR shareholders received 1.312 Northeast Utilities common shares for each NSTAR share that they own. The merger was completed in 2012. On February 2, 2015, Northeast Utilities and all its subsidiaries, including NSTAR, began to brand themselves as Eversource Energy.

PCB spill controversy

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.