Charlotte Peeler Gannett, 58, an environmentalist dedicated to working for the abatement of pollution in the Potomac River and Chesapeake Bay, died Friday at her home in Chevy Chase after a heart attack.

At the time of her death, she was president of the Montgomery Environmental Coalition, a citizens group that she founded seven years ago.

While she held no public office and had no professional background in the field of water quality, Mrs. Gannett drew respect for her determination in battling pollution.

Her greatest victory, probably, came when the Environmental Protection Agency doomed Montgomery County's attempt to build a huge sewage treatment plant at Dickerson.

Mrs. Gannett was "an environmental resource that will be terribly missed... We will have to pick up where she left off, but that will be a hard thing to do. She brought such knowledge and dedication to the job," B.C. Nagelvoort, immediate past president of the Montgomery Environmental Coalition, said yesterday.

Mrs. Gannett was born in Booneville, Miss., and grew up in Ashland. She was a graduate of Millsaps College in Jackson, Miss. During World War II, she served as an officer in the WAVES in Corpus Christi, Tex.

She first came to the Washington area in the late 1940s and was a member of the UNESCO relations staff of the State Department at the time of her marriage in 1951 to Michael R. Gannett, a Foreign Service officer who is now retired. She accompanied him on assignments to Iran, Italy and Germany.

Mrs. Gannett became active in Montgomery County civic affairs while they were living there in 1958. She resumed those activities when they returned from Germany in 1971.

She had been active in county Democratic Party affairs.

In addition to her husband, she is survived by three sons. William, of the home, Lewis, of Boston, and Frederick, of Aspen, Colo.; a daughter, Margaret, of Boston; a stepson, Michael Jr., of New York; her mother, Willana Peeler, and a brother, John Edward Peeler, both of Ashland, Miss.

The family suggests that expressions of sympathy may be in the form of contributions to the Montgomery Environmental Coalition.