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(53-02) The use of aquatic toxicity data in South African water resource management. Scherman, P.-A.*,1, Palmer, C.G.1, Muller, W.J.1, Jooste, S.2, 1 Rhodes University, Grahamstown, South Africa2 Dept of Water Affairs and Forestry, Pretoria, South Africa ABSTRACT- The precautionary principle has been adopted by water resource managers in South Africa, and is encapsulated in the principles of the National Water Act No. 36 of 1998. The use of aquatic toxicity data as a tool for applying the precautionary principle is currently being explored and developed. This paper will report on new developments in South African water resource management, and the use of toxicological methods in both resource-directed measures and source-directed controls for the protection of aquatic resources. Resource-directed measures include tools such as in-stream water quality guidelines, and strategies for assessing the ecological Reserve for a water body, i.e. the quality and quantity of water required to maintain a functioning ecosystem. Source-directed controls include end-of-pipe standards, licenses and economic incentives necessary to control the quality of wastewaters entering water resources. Standards, or chemical substance-specific limits - dependent on chemical analysis for enforcement - have been traditionally used in South Africa, but are of limited use in authorising and controlling the environmental consequences of the discharge of complex chemical mixtures. Policy is currently being developed on how whole effluent testing, or direct toxicity assessment, can be used to effectively manage complex mixtures. Licence specifications are then in terms of a toxicity-test end-point, rather than a chemical concentration. The use of toxicity data in both resource-directed measures and source-directed controls is explained and case studies presented. Key words: Aquatic toxicology, Water Act, ecological Reserve, South Africa |
