Julius W. Fletcher, 67, proprietor of Fletcher's Boathouse on the Potomac River since 1950, died of cancer Saturday at his Washington home.

Fletchers have run the boathouse and lived on Fletcher's Landing for more than 100 years. The boathouse, located about halfway between Chain and Key bridges, is an establishment where boats, canoes and bicycles are rented, catering to fishermen, canoeists, and persons who bicycle along the C&O Canal path adjacent to the boathouse.

Mr. Fletcher was born in a house on the canal. He grew up in a part of the city his family once owned. It once consisted of houses that dotted the old Canal Road, a dirt path that led the two or three miles to Georgetown.

Mr. Fletcher grew to know the history of his family (he was the fourth generation to grow up on the canal) and his section of Washington. He also became an authority on the everchanging rocky nooks and niches along the riverbed.

He and his family knew where to find white perch, hickory and white shad, largemouth bass, catfish, crappies and rockfish.

Mr. Fletcher left the life of the river for a time. He worked as a steel foreman for a Washington construction company from 1930 to 1950 and was a member of local No. 301 of the steelworkers' union.

He also operated his own construction firm, Julius Fletcher & Sons, which built a number of private homes in Washington and Northern Virginia between 1950 and 1960.

He took over direction of the boathouse after the death of his father in 1950.

Mr. Fletcher helped lobby during the late 1950s for the construction of the new Sibley Memorial Hospital in Washington. He then served as superintendent of buildings and grounds at the new hospital from its 1961 opening until he retired in 1970.

He was a charter member of the Palisades Lions Club.

Survivors include his wife, Mary Ann, of the home in Washington; three sons, Joseph, of McLean, Gerald, of Van Nuys, Calif., and Raymond, of Arlington; two daughters, Jay Burgess, of Fort Lauderdale, Fla., and Linda McCrofskey, of Gales Ferry, Conn., and four grandchildren.

The family suggests that expressions of sympathy be in the form of contributions to the American Cancer Society.