Progression of river BOD/DO modeling for water quality management

A historical perspective of river BOD/DO modeling using the Streeter-Phelps equation in the past century is presented with cases in the United States, Taiwan, and India. The main emphasis is on the regulatory aspects of modeling during the five decades following the passage of the 1972 Clean Water Act (CWA) in the United States. Success of the CWA in river clean-up is demonstrated via BOD/DO modeling for management use. Continuing interests outside the United States in anaerobic rivers and eutrophication-related low dissolved oxygen problems are serving as new proving ground for applications of river BOD/DO modeling. In addition, road blocks on BOD/DO modeling under future conditions for water quality management are outlined. PRACTITIONER POINTS: Water quality-based control to set end-of-pipe limits prior to 1970s Switched to technology-based control following the 1972 Clean Water Act Back to water quality-based control with field data support since 1980 Modeling to support technology-based and water quality-based control for renewed river BOD/DO problems in the 21^st century.