After receiving his bachelor’s degree in civil engineering from Manhattan College in 1944, Don served in the U.S. Army Medical Corps in Europe during the final years of World War II. He returned home in 1946 ready to continue his studies and pursue his career. He completed his master’s degree in civil engineering at the Polytechnic Institute of Brooklyn in 1947 and accepted a job as a structural engineer with the design firm Parsons, Brinckerhoff, Hall and MacDonald. Away from the office, Don’s fancy was soon captured by Anita Lordi, a dress buyer for a New York–based department store. They married in 1948 and soon after had three children—Dennis, Arlene, and Jeanette.
While juggling the responsibilities of a full-time job and a new family, Don began his doctoral work in sanitary engineering at New York University. Shortly after, he left his full-time job as a structural design engineer to assume a full-time teaching position at Manhattan College. He continued his doctoral studies at night. Don’s research initially focused on the hydraulics of side-channel weirs for combined storm water systems. However, he found water quality issues much more challenging, and he was particularly intrigued by what happened to oxygen levels in streams impacted by wastewater discharges. This led Don to reexamine the Streeter-Phelps equation, which he had first studied at Manhattan College 10 years earlier.
Don received his doctorate in engineering science from New York University in 1956 for his dissertation titled “The Mechanism of Reaeration in Natural Streams.” This work established the basis for quantitative definition of the reaeration coefficient in streams. It is still being used today and is the basis of the O’Connor-Dobbins equation, named after Don and his doctoral adviser, William Dobbins.
Don’s work on reaeration was followed by further work on dissolved oxygen depletion in streams. He extended the range of applicability of the Streeter-Phelps dissolved oxygen equation with the addition of the photosynthetic source, nitrification, and benthic sinks. His most lasting accomplishment, though, was his solution to the estuary problem, which involved application