The operators of an Agawam power plant pleaded guilty to federal charges earlier this week that accused the plant's owner and managers of tampering with emissions equipment and submitting bogus reports to regulators.

Berkshire Power Plant and its management company, Power Plant Management Services, agreed to pay $8.5 million in fines stemming from the charges.

In a statement, US Attorney Carmen M. Ortiz addressed the agreement:

“This resolution addresses a pattern of behavior by multiple persons and entities in obstructing the enforcement of laws designed to protect the air we breathe."

Prosecutors say the companies altered an oxygen monitor on a Continuous Emissions Monitoring System to save money, delay repairs and avoid reporting that the Agawam plant was releasing pollutants above hourly legal limits.

Frederick Baker, the plant's operations and maintenance manager, also pleaded guilty Tuesday to charges of conspiracy to violate the Clean Air Act and tampering. The Southampton man faces up to five years in prison.