Lawrence M. Fisher, 92, a retired commissioned officer with the U.S. Public Health Service who was active in Montgomery County affairs, died Thursday at Suburban Hospital in Bethesda.

He had been in declining health since February, when he suffered a broken hip after falling while on a walk in Daytona Beach, where he was vacationing.

An authority on water supply, sanitation and public health administration, Mr. Fisher retired from the USPHS in 1950 as a sanitary engineer director in the office of the surgeon general here.

He had joined the federal organization during World War I. Later he was detailed to the South Carolina Board of Health, worked on international aspects of stream pollution with the International Joint Commission of the United States and Canada and with the U.S.-Mexico Border Public Health Association.

Mr. Fisher was with USPHS offices here from 1934 to 1941, then spent five years at the Chicago office before returning here in 1946.

After his retirement, he spent several years as a consultant to the American Public Health Association, and in 1954-55 was acting director and then director of the Interstate Commission on the Potomac River Basin. He went to Geneva, Switzerland in 1955 to prepare a manual on airport hygiene and sanitation for the World Health Organization.

A resident of Garrett Park from 1946 until moving to Rockville in 1973, Mr. Fisher had been chairman of public health committees of the Garrett Park Citizens Association and the Montgomery County Civic Federation.

He also headed the Montgomery County Health Advisory Committee and directed the Potomac River Development Association. He had helped in the establishment of a fire board for the Kensington area. In 1954, he ran unsuccessfully as a Democratic candidate for the Montgomery County Council.

Mr. Fisher was born in Berne, Pa. He received bachelor of science and civil engineering degrees from Pennsylvania State University. He also held an honorary doctorate in public health from the University of Georgia.

He worked for the bureau of health in the Philippines and the Pennsylvania Health Department before joining USPHS.

He wrote numerous articles for technical journals and was a member of various organizations in his field, including the American Society of Civil Engineers, the American Water Works Association, the Inter-American Association of Sanitary Engineering, the American Public Health Association and the Federal Sewage Research Association.

He is survived by his wife, Muriel, of the home in Rockville; two sons, Philip E., of Edgewood, Md., and Lawrence L., of Arlington; three daughters, Sarah Kandel, of Arlington, Ethel Steiner, of Ellicott City Md., and Irma C. Fisher, of Rockville, 12 grandchildren and 13 great-grandchildren. CAPTION: Picture, LAWRENCE M. FISHER