Douglas M. Costle, who helped draw up the blueprints for the federal Environmental Protection Agency and served as its administrator when it tackled toxic waste sites and fluorocarbons and monitored radioactivity from the Three Mile Island nuclear disaster, died on Jan. 13 at his home in McLean, Va. He was 79. His wife, Elizabeth, said the cause was complications of a stroke. Douglas Michael Costle was born on July 27, 1939, in Long Beach, Calif., to George and Shirley (Ellinghaus) Costle. His mother was a medical administrator, his father an engineer. He was raised in Washington State, where his appreciation for nature was nurtured during fishing trips with his father to Spirit Lake, near Mount St. Helens. He earned a bachelor’s degree in history from Harvard in 1961, graduated from the University of Chicago Law School in 1964 and worked as a trial lawyer in the Justice Department’s civil rights division under Attorney General Robert F. Kennedy. He also served in the Army Reserve, in military intelligence. After Richard M. Nixon was inaugurated in 1969, Mr. Costle was recruited by a friend to the White House Advisory Council on Executive Organization. He played a major role in conceptualizing the environmental agency, which Nixon created by executive order in December 1970. Appointed to head the agency by President Jimmy Carter in 1977, Mr. Costle (pronounced KOSS-tul) recruited 600 scientists and other professionals within two months of taking office at what was already the government’s largest regulatory body. He was instrumental in creating the so-called Superfund to decontaminate toxic waste sites after the Love Canal health crisis near Niagara Falls, N.Y., and oversaw a $400 million agreement with United States Steel to curtail air pollution. Mr. Costle was the administrator when the agency banned aerosol spray fluorocarbon gases in 1978 and when it was assigned the lead role in monitoring the release of radioactivity after the partial meltdown of the Three Mile Island nuclear power plant reactor in Pennsylvania in 1979. As E.P.A. administrator, a position he held until 1981, Mr. Costle was in the vanguard of the federal government’s efforts, not all of them successful, to define safety metrics for toxic chemicals and metals and enforce limits, while the White House was also weighing the inflationary impact of regulation. After Mr. Carter was defeated for re-election in 1980 and Mr. Costle left the agency, he joined an environmental testing company, served as dean of Vermont Law School from 1987 to 1991 and unsuccessfully sought the Democratic nomination for United States senator from Vermont in 1994. He moved to McLean in 2003. In addition to his wife, Elizabeth (Rowe) Costle, he is survived by a daughter, Caroline Costle; a son, Douglas Jr.; and three grandchildren.