Born in 1927 in The Hague, The Netherlands, to Cornelis van der Leeden and Clara van Leer, Fritz van der Leeden survived the German occupation and served in the Dutch Air Force in Indonesia.

In 1950, he immigrated to the United States and continued his undergraduate education at the City College of New York, where he met his wife, Jacqueline.

Later, he obtained a master of science degree in geology at New York University. Following employment at the American Geographical Society, he joined the exploration staff of the Standard Oil Company.

In 1963, he joined groundwater consulting company Geraghty & Miller, rising to senior vice president. He retired in 1997. Among his consulting work were investigations of groundwater availability and quality for municipalities, private industry, and government, including Superfund site studies for the Environmental Protection Agency and the Department of Justice.

Overseas, his consulting work carried him to water supply projects in Europe, the Middle East, Africa and South America. He authored numerous water resources publications including The Water Encyclopedia, and after retirement to Lexington, The Water Atlas of Virginia, The Environmental Almanac of Virginia and Groundwater Resources of Rockbridge County. He stayed active in environmental affairs throughout his life and enjoyed landscape painting and gardening.

He is survived by his wife, Jacqueline; two daughters, Pam in Morgan Hill, Calif., and Ingrid in Margaretville, N.Y.; and son, John (Yolande); two grandsons, and two great-grandchildren in Ottawa, Canada; three brothers, Hans in Springfield, Mass., Ton in Santa Barbara, Calif., and Cees in Lommel, Belgium; and a sister, Nelly in Capelle an de Ijssel, The Netherlands.

In memoriam donations may be made to Earthjustice, 50 California St, Suite 500, San Francisco, CA 94111, www.earthjustice.org; or The Wildlife Center of Virginia, P O Box 1557, Waynesboro, VA 22980, www.wildlifecenter.org.