Discharger Grouping for Water Quality Control

In developing management programs to regulate point sources of waterbomewaste, it may be convenient or even necessary to subdivide the dischargers into groups. For simplicity and effectiveness in meeting water quality goals, it is desirable that the regulatory decisions governing one group of dischargers be minimally influenced by those governing other groups. One way to accomplish this is to separate the watercourse into sets of water quality checkpoints such that each set of checkpoints is associated with a group of dischargers and the effect of the dischargers excluded from a given group upon the checkpoints associated with that group is small. This paper presents a quantitative method for effecting such groupings. The method minimizes the impacts of the dischargers included in a group on checkpoints associated with other groups of dischargers. The method is illustrated using data for several river basins, viz., the Lower Fox River in Wisconsin, the Willamette River in Oregon, and the Mohawk River in New York.