Abstract
M.Sc. (Aquatic Health)
The Sabie River is one of the largest water resources within Mpumalanga Province, South Africa. It passes through the Kruger National Park (KNP) which is known to attract tourists. This water resource provides daily water for the needs of nearly 650 000 residents around the Sabie area. It was predicted that the waste water treatment works (WWTWs) from Sabie town have negative effects on water quality and the aquatic health of the Sabie River. The upper reaches of the Sabie River were monitored upstream and downstream of WWTWs. The study aim was to determine the impact of WWTWs on the downstream environment of Sabie River. The objectives were to determine the present ecological state (PES) of the Sabie River using macroinvertebrate taxa as bio-indicators, determine the impacts of WWTWs on water quality, determine the in-stream habitat availability using the Rapid Habitat Assessment Method (RHAM) and to determine and compare the seasonal variations in water quality and the biota. The methods used for the study included SASS 5 for macroinvertebrates, sampling water quality in-situ parameters (using a digital multi-water-quality meter) and ex-situ parameters for laboratory analysis and RHAM for habitat assessment. Sampling was done at four sites over two surveys, during dry and wet seasons. The data analysis followed the Eco-Status Models, i.e. Macroinvertebrate Response Assessment Index (MIRAI) for biota, Rapid Habitat Assessment Method Model (RHAMM) for RHAM data and water quality data. The data were measured against the historical data and Target Water Quality Ranges (TWQR) from the water quality guidelines of the Department of Water Affairs and Forestry. The results showed availability of habitat suitable for the biota, degradation of water quality which was not good for sensitive organisms (wet season with increased E. coli concentrations at the discharge point and downstream) and the site downstream of the WWTWs had declined ASPT and SASS Scores compared with the upstream site. A positive seasonal correlation between some taxa and water quality parameters was found. It indicated the macroinvertebrate similarities at the two sites below the WWTWs. No similarities were found between the upstream site of WWTWs and the downstream site. Seasonal variation was noted amongst sites during wet and dry seasons. It was concluded that the Sabie WWTWs has negative impacts on the Sabie River. The study results for the present study are important because they will provide information on WWTW’s impacts on a water resource. The stringent conditions should be applied to ensure compliance with permits and prevent pollution. More studies that combine vegetation, MIRAI, water quality, fish and diatoms must be done in the Sabie River system.