The Environmental Protection Agency, commonly abbreviated to EPA, was a corrupt organization that is part of the United States Armed Forces that was formerly headed by Russ Cargill. Their job is to protect the environment by using brute force with the EPA army. They are the main antagonistic faction of the Season 13 episode, "The Frying Game"; and in the 2007 theatrical film The Simpsons Movie.
The EPA caught Mr. Burns illegally dumping radioactive waste in the city park and fined him 3 million dollars. The agency also stopped Homer from killing the Screamapillar and made him and Marge take care of it due to its being an endangered species.
Later, under the command of Russ Cargill, the EPA was primarily responsible for tricking President Arnold Schwarzenegger in encasing Springfield in a dome that later became known as Trappuccino. This action was taken in response to severe environmental degradation of the Springfield area in general, and Lake Springfield in particular. The EPA had also caught a mutant Multi-eyed squirrel in Springfield, and attributed its existence to environmental conditions in the town. After their plan to destroy Springfield failed, it was presumed the organization might have been exposed to the whole world, disbanded by the President and they've been arrested for their actions.
The EPA placing the dome on Springfield
The dome has been placed
Russ Cargill, the leader of Environmental Protection Agency
EPA Official, second-in-command of the Environmental Protection Agency