Omar Johansen Lillevang was born on September 8, 1914. He graduated from the University of California, Berkeley in 1937 with a Bachelor of Science degree in Civil Engineering. Under the direction of Morrough P. O'Brien, Lillevang was introduced to coastal engineering and wrote his senior thesis on two sand movement and shoaling model studies (Santa Barbara and Santa Monica, California). His specialty during his long engineering career was in the design of nearshore sited armored structures constructed of material ranging from stone to special concrete armor units.

From 1938 until 1943, Lillevang worked with the firm of Quinton, Code and Hill-Leeds and Barnard, involved in the practice of civil engineering. During World War II (1943-1946), he served as a diving and marine salvage officer with the U.S. Naval Construction Battalions, the Seabees, on the South Pacific. In 1946 he joined the staff of the Los Angeles consulting engineering firm of Leeds, Hill and Jewett, the same firm that he had worked for before the war. The firm provided engineering services generally related to private, corporate, and governmental entities with the responsible engineer on each project usually also in direct charge of construction surveillance. Lillevang served as Senior Engineer and Project Engineer on a wide variety of the firm's projects. In 1960, he became Vice President in charge of the firm's coastal and harbors works. In 1964, he left Leeds, Hill and Jewett and began practicing independently as a consulting civil engineer specializing in coastal engineering. One of Lillevang's primary objectives throughout his 30 years of private practice was to avoid office growth so that he could remain directly involved in all aspects of a project from preliminary to final design.

During his career, Lillevang was involved in the conceptual and final design of nearly twenty breakwaters constructed from stone or special concrete shapes. His direct involvement in physical model studies of more than half of these provided Lillevang with a unique approach to marine structure design using the model study results as a design tool. A major effort for a number of years dealt with the design and subsequent upgrade of the breakwaters of the Diablo Canyon Nuclear Power Plant of the Pacific Gas and Electric Company. Prior to this engagement he was involved in coastal aspects of several other nuclear power plants, including San Onofre Nuclear Power Plant for the Southern California Edison Company, and the initial design of an artificial island for a nuclear power and sea water conversion plant for the Metropolitan Water District of Southern California.

Lillevang's coastal engineering expertise often was sought overseas as well as in the United States. He was actively engaged in projects in Hong Kong, Israel, New Zealand, Peru, Mexico, Canada, and South Africa. He was a professional engineer registered in California and several other states. He was a Fellow of the American Society of Civil Engineers, a member and Director of the American Shore and Beach Preservation Association, and a member of the Permanent International Association of Navigation Congresses, the United States Power Squadrons, and the Society of American Military Engineers. In 1980, Lillevang was the recipient of the ASCE's John G. Moffatt-Frank E. Nichol Harbor and Coastal Engineering Award.

Omar J. Lillevang died January 23, 2000 from complications of a stroke.

Adapted from "In Memoriam," by Fredric Raichlen, Shore & Beach, Vol. 68, no. 2 (April 2000), p. 28.