South African rivers generally receive waste from inadequate wastewater infrastructure, mines, and farming activities, among others. The uMsunduzi River in KwaZulu-Natal, South Africa, is among these recipients with recorded poor to very poor water quality. To identify parts of the uMsunduzi River that are polluted by Cryptosporidium and Escherichia coli (E. coli), this study mapped out pollutants emanating from point and non-point sources using the Soil and Water Assessment Tool (SWAT). Streamflow calibration in the upper and lower reaches of the catchment showed good performance with R² of 0.64 and 0.58, respectively. SWAT water quality output data were combined with a Quantitative Microbial Risk Assessment (QMRA) to understand the microbial health implications for people using river water for drinking, recreational swimming, and non-competitive canoeing. QMRA results for Cryptosporidium and pathogenic E. coli showed that the probability of infection for most users exceeds the acceptable level for drinking and recreation as outlined in the South African water quality guidelines, and by the World Health Organization (WHO). The results of this study can be used as a baseline to assess the economic and health implications of different management plans, resulting in better-informed, cost-effective, and impactful decision-making.

南非河流通常会因废水基础设施、矿山和农业活动等不足而接收废物。南非夸祖鲁-纳塔尔省的 uMsunduzi 河是这些受水者之一，其水质记录为差到极差。为了确定受隐孢子虫和大肠杆菌( E. coli )污染的部分 uMsunduzi 河，本研究使用土壤和水评估工具 (SWAT) 绘制了点源和非点源排放的污染物。流域上游和下游的流量校准显示出良好的R ^2性能分别为 0.64 和 0.58。SWAT 水质输出数据与定量微生物风险评估 (QMRA) 相结合，以了解微生物对使用河水饮用、休闲游泳和非竞技划独木舟的人的健康影响。隐孢子虫和致病性大肠杆菌的QMRA 结果表明，大多数用户的感染概率超过了南非水质指南和世界卫生组织 (WHO) 中规定的饮用和娱乐可接受的水平。本研究的结果可用作评估不同管理计划的经济和健康影响的基准，从而做出更明智、更具成本效益和更有影响力的决策。