A western Massachusetts power plant has pleaded guilty to felony charges of tampering with emissions equipment and submitting false information to environmental and energy regulators in a profit-motivated scheme.

Berkshire Power Co., the Agawam, Mass.-based power-plant owner and management company, and Power Plant Management Services, the plant manager, pleaded guilty on May 3 in federal court to seven counts of conspiracy to violate the Clean Air Act and agreed to pay $8.5 million to resolve the case. Sentencing is set for August.

Frederick Baker, the plant operator, also pleaded guilty to related conspiracy charges and faces up to five years in prison. Scott Patterson, a plant instrument-control technician during the time of the tampering, pleaded guilty last year.

The settlement follows a joint federal and state investigation that detailed tampering with air-pollution monitoring equipment between 2009 and 2011, as well as false data reporting to environmental energy regulators regarding emission levels and the availability to produce power, according to a statement by U. S. Attorney General Carmen Ortiz and Massachusetts AG Maura Healy.

The plant’s so-called Continuous Emissions Monitoring System was set to show lower emissions levels than the plant was producing.

“The deliberate scheme Berkshire Power Plant management and staff undertook gave them an unfair competitive advantage over responsible companies and undermined a system that depends on honest data reporting,” said Tyler Amon, special agent in charge of the U.S. Environmental Protection Agency’s Criminal Investigation Division in Boston. To protect clean air, the EPA will continue to pursue cases in which data integrity is suspect, he added.

“Fraud against the commonwealth is very serious and will be aggressively prosecuted, criminally and civilly, by this office,” Healey said.

Settling the first-ever criminal charges to be brought under the federal power act, Power Plant Management also agreed to plead guilty to making false statements to ISO-New England, the regional power-grid administrator, regarding the plant’s availability to produce power.

Berkshire Power, Power Plant Management and EthosEnergy Power Plant Services, the plant’s former operator, also will pay $4 million in civil penalties.

Massachusetts Dept. of Environmental Protection Commissioner Martin Suuberg said some of the funds generated by the settlement will support innovative programs to improve air quality throughout the state.