The department oversees the state's natural resources and environment and regulates public utilities and energy policy.

The agency was created on July 1, 2011, by the merging of two other state agencies, the Connecticut Department of Environmental Protection and the Connecticut Department of Public Utility Control.

[1] Daniel C. Esty was appointed as commissioner of the DEEP upon its creation in July 2011.

Rob Klee served as commissioner of the department from January 2014 through December 2018.

The law enforcement branch of DEEP is the Connecticut State Environmental Conservation Police.