Renewed Use of BOD/DO Models in Water Quality Management

Immediately following the passage of the Clean Water Act over 25 years ago, there was a need to develop water quality management plans (WQMP) for each watershed. Assimilative capacities and wasteload allocations were quantified using primitive tools because of limited water quality data and the lack of skilled modeling professionals. As the quality of receiving waters improves due to increased treatment of waste flows over the last two decades, existing models require updating or postauditing to continue to support the WQMP. In some cases, as presented here, the quality of the waters always met standards, although an old model predicted nonattainment. This situation indicates that there is a need for increased use of water quality models to review the assimilative capacity of the receiving water for regulatory control and water quality management. Finally, the work presented in this paper demonstrates that modeling continues to be the most cost-effective method of water quality planning and that water resource managers should apply water quality modeling on a regular basis to support the present and future needs of the watershed.