In 2002, NSTAR Electric and Gas Corporation was cited by the Environmental Protection Agency for discharging oil into the Charles River. The EPA also stated that NSTAR had failed to prepare spill plans at four of its facilities, in Brighton, Cambridge, Needham, and West Roxbury, where oil is pumped through their pipe lines. In July 2007, NSTAR Electric introduced a new program called NSTAR Green. In May 2008, NSTAR Green signed ten-year contracts for sixty megawatts of wind power from two wind farms in New York and Maine. They offered their customers a chance to buy 50-100 percent of their power from these wind farms. Power purchased through NSTAR Green would reduce reliance on fossil fuels that are traditionally used to meet the region’s electricity demand.
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. 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.
HVDC transmission
NSTAR has signed on a joint venture with Hydro-Québec and Northeast Utilities to build a new High-voltage direct current line from Windsor, Quebec to a location in central New Hampshire. It is projected that the line will either run in existing right-of-way adjacent to the HVDC line that runs through New Hampshire, or it will connect to a right-of-way in northern New Hampshire that will run through the White Mountains. This 180- to 190-mile line, projected to carry 1,200 megawatts, will carry electricity to approximately one million homes.
Merger with Northeast Utilities
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".