Another aspect to take into account in assigning priority is the geographical extent of the impact, . whether a particular problem, for example caused by a discharge of wastewater, has only a local impact in an area of a few hundred meters along the river or whether there is an impact in the entire river system downstream of the discharge. The likely answer depends, for example, on the size of the discharge and the retention time in the receiving water bodies, the degradability of the pollutant, and the occurrence of sensitive species in the receiving water body. In addition, the.
