Effect of Industrial Wastes on River Water Quality: A Case Study of Rwamagana Industrial Park on Rwamurinzi and Kiruhura Rivers, Eastern Province, Rwanda

Freshwater resources face increasing global threats from overuse, pollution and industrial expansion, with industrial wastewater introducing toxic pollutants that jeopardise human health and sustainable development. In Rwanda, rising industrialisation, particularly around industrial parks, has heightened risks to rivers such as Rwamurinzi and Kiruhura. This study assessed the impact of wastewater discharged from the Rwamagana Industrial Park on the quality of these rivers in Eastern Rwanda. Between January and March 2025, both wastewater effluents and river water samples were systematically collected from upstream and downstream sections. Samples were analysed for physico-chemical parameters, including pH, dissolved oxygen and electrical conductivity, as well as heavy metals—lead (Pb), cadmium (Cd), and chromium (Cr). Findings revealed that concentrations of Pb, Cd, and Cr in both wastewater and river water exceeded Rwanda Standards Board limits, while pH and electrical conductivity largely remained within acceptable ranges. The Kiruhura River showed notably higher heavy metal concentrations, closely resembling those in the industrial wastewater and significantly higher than levels in the Rwamurinzi River. Statistical analysis demonstrated a strong correlation between wastewater composition and river water quality, confirming industrial discharges as a primary contamination source. The results highlight the urgent need for improved wastewater treatment systems and stricter regulatory enforcement in industrial parks. While this study focused on water samples and three metals, future research should expand to include sediment analysis and a wider range of pollutants to fully capture the environmental impacts of industrial activities.