The study assessed the quality of the influent, effluent, sludge of the Malamulele Wastewater Treatment Plant (MWTP) and its impact on the water quality of Mandzoro River. In the effluent discharge, the levels of iron, zinc, copper and lead were 0.5 ppm, 0.1 ppm, 0.05 ppm and 0.02 ppm respectively. These heavy metals were also found in the dried sludge. The chemical analysis for phosphates and nitrates showed that they were absent from the upstream section but were present in the downstream section at phosphates (20 ppm) and nitrates (9 ppm). A high concentration of chloride was found in the effluent. The river health assessment, based on the absence or presence of certain macroinvertebrates, showed a presence of pollution resistant aquatic macroinvertebrates, the Psychodidae and Thiaridae which were found in the downstream, but were absent in the upstream.