Donald Siegel earned his doctorate at the University of Minnesota in Hydrogeology (1981) after being employed by Amerada Hess for whom, 1972, he supervised the drilling and hydrofracturing of a two-mile deep oil well. After earning his doctorate, Siegel joined the U.S. Geological Survey as a research hydrologist. There, Siegel studied aquifer systems, oil and gas spills, acid rain, wetlands, and lake hydrology. Siegel joined Syracuse University in 1982 and taught water science and water chemistry there for 35 years. 

Siegel served on environmental panels of the National Research Council (NRC, part of the National Academies of Science and Engineering), and as the chairman of its National Water Science and Technology Board which advised the Nation on water issues. Siegel has won many awards from Professional Societies for his contributions to hydrogeology, edited most professional journals publishing research on water issues, and published far too much (by his own account). In 2022, the American Geological Institute awarded him the Marcus Milling Legendary Geoscientist Medal in recognition of his high-quality basic and applied science achievements in the Earth sciences.

Syracuse University appointed him to a Chaired Professorship in recognition of for his mentoring and teaching as well as his research. Beyond his academic work, Siegel provided his scientific expertise to major Federal Agencies, Congress, companies, and environmental groups, published a best-selling Chinese cookbook from which he was invited to compete on the TV Food Channel and compete in a culinary competition in China. He performs, time permitting, solo finger-style jazz on a classical guitar at receptions, wineries, and other venues.