Train stayed in the post through the Gerald Ford presidency and had a hand in other landmark environmental laws like the Endangered Species Act and the Clean Air Act.
The chairwoman of the Council on Environmental Quality, Nancy Sutley, said Train played a pivotal role in the government's efforts to protect the environment.
"He was a serious and widely respected voice on environmental issues at a time when Americans first became broadly aware of the dangers posed by pollution to our air, waters and soils," Sutley said. "On his watch, the United States stood up many of our landmark safeguards for public health and the environment."
Train also served as the first president of the World Wildlife Fund's American chapter, leading that group from 1978 to 1985.
The Post said Train died Monday at his farm in the town of Bozman on Maryland's Eastern Shore. There was no cause of death reported.