1992 Pulitzer Prize Gold Medal for Public Service, .Sierra In Peril"..Martin Litton (born February 13, 1917) is a Grand Canyon river runner and a longtime environmental activist, best known as a staunch opponent of the construction of Glen Canyon Dam and other dams on the Colorado River..He has remained active in environmental causes. His most recent environmental activities have revolved around opposing logging in the Sequoia National Forest and the recently created Giant Sequoia National Monument, and campaigning to remove Glen Canyon Dam and drain Lake Powell..