Elizabeth Lee Scull, a scion of one of Montgomery County's most prominent families who became a political force in her own right and the County Council's liberal conscience died of cancer yesterday at the age of 57.

The daughter of Col. E. Brooke Lee, a gentleman farmer who for a generation reigned as the unchallenged patriarch of Montgomery County, Mrs. Scull entered politics in 1970 and earned a reputation as a champion of low-income housing and controlled growth.

Although she was diagnosed last August as having cancer of the colon, Mrs. Scull continued work on council issues until her death. She underwent surgery and chemotherapy treatment but still attended many of the meetings and followed council business.

Her energy for council work was unflagging. Three days ago she was on the telephone submitting amendments to a package of condominium bills.

"Her doctor said, 'Would you please start acting more like a patient and less like a dynamo?'" said her son, Maryland Del. David L. Scull.

Two months ago, Mrs. Scull moved from Silver Spring to her son's home in Chevy Chase, and it was there that she died.

"Her lifetime service and dedication to the principles in which she believed placed all of us in her debt," said County Executive Charles W. Gilchrist. "Betty was a warm friend, and a strong ally, a resolute fighter and a wise counselor."

"This is a sad day for Montgomery County," said Joyce Siegel, an official of the Housing Opportunities Commission who worked with Mrs. Scull on housing legislation.

Mrs. Scull was born into a family whose ties to Silver Spring go back to 1836, when Francis Blair began a farm there and called the spring on his property "Silver Spring."

She was a descendant of both Robert E. Lee and Henry "Light-Horse Harry" Lee, a general in George Washington's Revolutionary Army. Her grandfather, Blair Lee, was a U.S. Senator from Maryland and her brother, Blair Lee III served as acting governor.

Although born to great wealth, Mrs. Scull did not live a life of leisure, becoming instead an activist in community affairs and a family maverick.

Her father, Col. E. Brooke Lee, was chairman of the county's Democratic Party and a successful developer who gave his children stock now worth millions of dollars. Elizabeth Scull, or "Betty," as she was called, dared switch from the Democratic Party when she married David Scull, former county and state chairman for the Republican party. Later, she publicly opposed her father over issues of land use and low income housing.

Mrs. Scull worked closely on those issues with her husband. He died in 1968, a year and three months after his election to the Montgomery County Council. Mrs. Scull sought his seat.

When local Republican Party leader supported James Gleason for the vacant seat instead of her, Mrs. Scull returned to the Democratic Party.

Two years later, she was elected for the first of three terms, and each time she was the top vote-getter.

The County Council will appoint someone to Mrs. Scull's seat on June 19.

Mrs. Scull's vigorous support of low-cost housing made her a formidable opponent to no-growth advocates among the county's civic groups.

"She was strong, forceful and politically shrewd as all get out. She was an effective proponent of the issues she cared about," said Peg McRory, who was Mrs. Scull's aide on the council before becoming a housing consultant.

Mrs. Schull worked to get improved housing for the black community in Tobytown and helped shape laws such as the Moderatley Priced Dwelling Unit legistaltion that requires a minimum number of affordable apartments or homes in new developments of 50 units or more.

"I am Elizabeth Lee," Mrs. Scull told an interviewer last year. "That had meant that people have made assumptions all my life that I'm part of one big family political machine."

Besides her father and son, she is survived by her mother, Elizabeth Aspinwall of Washington; a daughter, Elizabeth S. Oelhaf of Chatham, N.Y.; two brothers, Blair Lee III of Silver Spring and E. Brooke Lee Jr. of Falmouth, Maine,; a half-brother, Bruce Lee of New York City, and three grandchildren.