The Keiskamma River and the impoundment, downstream were characterised over a one-year period by using standard physicochemical methods to assess their present qualities. The pH levels are normal in the river and in the impoundment but turbidity values and the levels of electrical conductivity are high in both water systems. Also, the nutrient levels in both systems are eutrophic. The DO and BOD levels exceeded EU guideline values for the protection of the aquatic ecosystem. The Keiskammahoek Sewage Treatment Plant (KSTP) was identified as a pollution point source into the receiving river and the impoundment. Its treatment performance was investigated. Significant pollution of the river and the impoundment from the KSTP was indicated for electrical conductivity, nutrients and oxygen-demanding substances.