Assessment of approaches to determine the water quality status of South African catchments

Abstract

The paradigm shift in water quality management of South African water resources was based on current international trends. This significant move was from a previous emphasis on source management to a focus on finding a balance between water resource protection and water use. The current approach requires that water quality and quantity should be maintained for sustainable functioning of both the natural aquatic environment and socioeconomic development. This approach has placed the assessment of water quality status as a key decision tool in water quality management. Various assessment tools have been utilized to quantify the quality of South African water resources. In this study we assessed the compatibility of some of the methodologies that have been used in the Department of Water Affairs to determine and report on the water quality status of the resource. During the assessment the context and manner in which these methodologies can be utilized in water quality management were also addressed The Compliance Evaluation and Fitness for use categorization methodologies are both used to describe the water quality threshold of potential concern when dealing with the resource. Compliance Evaluation methodology uses a pass or fail assessment, while the Fitness for use categorization methodology uses a scaled approach allowing for the assessment of gradual change in the system. The out puts of these two methodologies, the Resource Water Quality Objectives and Fitness for use categories/ classes have both been used in the department as benchmarks to describe the current water quality status The assessment of the two methodologies indicated that there are similarities in the approaches and the principles behind the two processes. The observation of the results, however, indicated differences in the manner of presentation of the results, the interpretation of the outcome and in how water quality management measures that needs to be implemented are linked. Both methodologies are easy to apply when conducting water quality status assessments. However, the two methodologies are not sufficient on their own when making decisions on water quality management. It was concluded that although the compliance evaluation methodology can play a pivotal role when setting end of pipe standards, the process needs to consider the gradual changes of water quality in the river system in order to enable instigation of different water quality management measures at appropriate levels. Further it was recommended that with some modification the two approaches can be applied to assess water quality to support adequate water quality management decisions at various levels.