Urban Storm Water Discharges: Effects upon Plankton Communities

Abstract

From 1985 to 1987, effects of sewer discharges on communities of phyto- and Zooplankton in receiving waters have been studied. Locations all over The Netherlands have been selected. The results were related to the type of sewer system, the discharges and the characteristics of the receiving water. Results were compared with those from samples taken from a corresponding water not influenced by sewer discharges, the reference water. Often either phyto- or Zooplankton communities could be used succesfully to describe the short-and medium-term effects of the discharges on the quality of the involved habitats. Plankton communities could also indicate permanent effects due to higher saprobic levels in the receiving water compared to the reference water: an obvious result of urban storm water discharges. In small and medium-sized stagnant waters, particularly in the immediate vicinity of the overflows, effects on plankton communities were more pronounced compared to large and running waters. Combined sewer system overflows (CSO) often proved to affect plankton communities more severely than separate sewer system discharges (SSD), except for some locations in industrial areas.