Carl D. Fetzer, 68, a retired Agriculture Department authority on water resources, died Wednesday at his home in Arlington of complications from the flu.

He was assistant director of the river basins division of the Soil Conservation Service when he retired in 1970.

Born in Sunbury, Pa., Mr. Fetzer received a degree in forestry from Pennsylvania State University. He also attended Iowa State University.

He joined the Soil Conservation Service in 1935 and served at various locations in North Carolina. He came to the river basins division in Washington in 1955.

Mr. Fetzer complied an Atlas of River Basins that became an important reference work used throughout government.

He represented the Soil Conservation Service in many cooperative studies with the Army Corps of Engineers and other U.S. and state agencies.

These studies included a comprehensive review of natural resources in the Potomac River Basin as well as similar studies of the Delaware and Cape Fear Rivers.

During World War II, Mr. Fetzer served with the Army Corps of Engineers, seeing duty in North Africa.

He was a member of the Society of American Foresters and the Soil Conservation Society of America.

He is survived by his wife, Winnie Fetzer, of the home; a brother, Bill, of Baltimore, and a sister, Ruth Richman, of Delray Beach, Fla.

The family suggests that expressions of sympathy may be in the form of contributions to Children's Hospital.