Gaylord Nelson, a former governor and U.S. senator from Wisconsin and the founder of Earth Day, died Sunday morning. He was 89.

Nelson died at his home in Kensington, Maryland of cardiovascular failure.

Family spokesman and Nelson's biographer Bill Christofferson says Nelson died peacefully with his wife beside him.

Twenty-five years after the first Earth Day, April 22nd is still a day on which many people plant trees, clean up trash and lobby for a clean environment.

Nelson was a conservationist years before it became fashionable. He was recognized as one of the world's foremost environmental leaders.

Then-President Clinton presented Nelson with a Presidential Medal of Freedom in 1995 for his environmental efforts.

Clinton called Nelson the father of Earth Day and the grandfather of all that grew out of that event, including the Environmental Protection Act, the Clean Air Act, Clean Water Act and the Safe Drinking Water Act.

Governor Doyle has ordered flags to fly at half staff at all state buildings. The order will stay in effect until Nelson's funeral, which
hasn't been set.

A Doyle spokesman says the governor's office is working with Nelson's family to have some type of memorial service at the state Capitol in Madison.

(Copyright 2005 by The Associated Press. All Rights Reserved.)