Rationale for an ecological risk approach for South African water resourcemanagement

The principle of ecosystem protection in the South African Water Act requir es that water resource management tools for a multiple stressor environment be tailored to the characteristics of the aquatic ecosystem. The requireme nts of the Act, the characteristics of aquatic ecosystems as well as co-occ urrence of diverse stressors are considered. Although single substance crit eria have a useful role, they are not sufficient for resource management wi thin the context of the ecological reserve. It is proposed that an effect-l ikelihood approach has the potential to address the variability and uncerta inty in management of a surface water body subject to multiple stressors. A n in-stream receiving water risk objective approach might be considered.