in customer satisfaction among utilities in the northeastern United States in 2010, according to TQS Research. The recent recognition marks the sixth consecutive year large commercial and industrial customers rated Allegheny Power the region's top performer. Southwestern Pennsylvania, excluding the city of Pittsburgh, provided about half of regulated utility revenues. Environmental policies, practice and record Allegheny has indicated that its policy is "to produce and distribute electricity in a reliable and responsible manner that protects its personnel, communities, customers, and the environment." In February 1995, the company signed a participation accord with the United States Department of Energy as a participant in the Climate Challenge Program. Under this accord, Allegheny Energy agreed to reduce its greenhouse gas emissions (as carbon dioxide equivalents) by two million tons per year by 2000. Through a series of reduction efforts including demand side management programs, heat-rate, and efficiency improvements on generation equipment, transportation alternatives, and land-use management involving forestation and vegetative sequestration efforts, Allegheny was able to achieve just under 8.5 million tons of carbon dioxide-equivalent reductions. These reductions fulfilled the company's Climate Challenge commitment goal by the calendar year 2000. Carbon dioxide reduction efforts have continued since 2000, and Allegheny has since recorded another 9 million tons of avoided emissions through continued efficiency improvements, demand-side management measures, and vegetative sequestration. The company complied with current sulfur dioxide emissions standards through a system-wide plan combining the use of emission controls, low sulfur fuel and emission allowances. Allegheny has taken steps to significantly reduce sulfur dioxide emissions at its generating facilities, investing $1.3 billion to install clean air technology at both the Hatfield's Ferry and Fort Martin power stations. With the addition of scrubbers at these plants, 85 percent of its coal-fired fleet now utilizes the best available controls for reducing sulfur dioxide emissions. Allegheny now has one of the cleanest fleets in the United States with respect to sulfur dioxide. The scrubber projects will also significantly reduce mercury emissions at these power stations. 2005 litigation In 2005, New Jersey, New York, Pennsylvania, Connecticut, and Maryland filed suit in the United States District Court for the Western District of Pennsylvania against Allegheny Energy. The suit claimed that Allegheny Energy has made major upgrades at its Armstrong, Hatfield's Ferry, and Mitchell electric generating stations, having dramatically increased emissions without installing new pollution controls required by the Clean Air Act. A trial was held in 2010. But