Lloyd G. Signell, 78, a retired soil conservation and flood control specialist for the Department of State who later worked as a consultant for the Department of Agriculture, died Monday at George Washington University Hospital. He had Parkinson's disease.

Mr. Signell began his federal career with the Agriculture Department in Milwaukee in 1933. In the mid-1940s, he transferred to the department's Soil Conservation Service here, which he headed from 1946 to 1953.

He then joined the State Department's old Technical Cooperative Administration and spent two years as an engineering consultant to the ministry of agriculture in Indonesia as part of the Point Four technical assistance program.

After becoming a Foreign Service reserve officer in 1955, Mr. Signell was assigned to India and Turkey. While in India, he helped strengthen soil conservation in the north and in the south and in Nepal, and taught agricultural engineering.

In Turkey, he set up about 100 work camps and appointed village leaders to supervise programs in conservation, forestry and irrigation.

Following his retirement in 1963, Mr. Signell was a consultant in Tanzania, Senegal and in Guatemala for the Agriculture Department.

A native of Rockford, Ill., he earned a bachelor's degree in civil engineering from the University of Illinois and did past graduate work at the University of Wisconsin.

He and his wife, the former Ottlie Burdick, lived in Leesburg, Fla., from 1963 until last year, when they returned to Washington.

Besides his wife, survivors include two sons, Karl, of West Hyattsville, and Peter, of East Lansing, Mich.; a daughter, Karen of San Francisco, and three grandchildren.