INTEGRATING STRESSOR AND RESPONSE MONITORING INTO A RESOURCE-BASED WATER-QUALITY ASSESSMENT FRAMEWORK

South African water law as well as the country's water resource manage ment policies are currently under review. The Water Law Principles, wh ich were established as part of this review process, indicate a commit ment to sustainable development of water resources and the protection of an ecological ''reserve.'' Such policy goals highlight the limitati ons of traditional and current water-quality management strategies, wh ich rely on stressor monitoring and associated regulation of pollution . The concept of an assimilative capacity is central to the implementa tion of the current water-quality management approach. Weaknesses inhe rent in basing water management on the concept of assimilative capacit y are discussed. Response monitoring is proposed as a way of addressin g some oi the weaknesses. Following a global trend, the new policy goa ls emphasize the need to protect rather than to use the ability of eco systems to recover from disturbances. This necessitates the adoption o f response measurements to quantify ecological condition and monitor e cological change. Response monitoring focuses on properties that are e ssential to the sustainability of the ecosystem. These monitoring tool s can be used to establish natural ranges of ecological change within ecosystems, as well as to quantify conceptually acceptable and unaccep table ranges of change. Through a framework of biological criteria and biological impairment standards, the results of response monitoring c an become an integral pari of future water resource management strateg ies in South Africa.