Gordon K. Zimmerman, 70, a retired executive vice president of the National Association of Conservation Districts and a former official of the Soil Conservation Service in the Department of Agriculture, died of cancer Sunday at his home in Alexandria.

Mr. Zimmerman was born in Spokane, Wash., and grew up in Wisconsin and the District of Columbia. He earned a degree in business administration at the University of Maryland.

In 1935, he went to work at the Soil Conservation Service, which was formed about that time, and eventually became an aide to Dr. Hugh Hammond Bennett, its first director. Mr. Zimmerman was the director of the service's public affairs division when he resigned in 1950.

He spent the next year working for an agriculture machinery manufacturer in Detroit and then returned to Washington. He was named research director of the National Grange. Among other things, he helped lobby for the passage of the Watershed Protection and Flood Prevention Act.

In 1958, Mr. Zimmerman opened the Washington office of the National Association of Conservation Districts. This is an organization of more than 3,000 local subdivisions of state government that are the beneficiaries of federal soil conservation programs. In 1964 and again in 1973, Mr. Zimmerman was chairman of the steering committee of the National Watershed Congress. He retired at the end of 1976.

Mr. Zimmerman was a member of the Soil Conservation Society of America and a two-term chairman of the Natural Resources Council of America. He also was a member of the President's Advisory Committee on Recreation and Natural Beauty and served on the boards of a number of national agricultural organizations.

Survivors include his wife, Jean, of Alexandria; one daughter, Karen Gudinas of Annandale, and two grandchildren.