Freshwater has a significant role in determining the ecological environment, public health and socio-economic development. This study analyzed the spatio-temporal variation in surface water quality of the tropical reservoir Mettur, India, to determine whether its water is suitable for human consumption and aquatic ecosystem. Thus, 21 water quality parameters were monitored seasonally (pre-monsoon, monsoon and post-monsoon) at nine sampling sites covering riverine, transitional and lacustrine zones of the reservoir during 2018. The study revealed spatial variation, which was due to input from industrial and domestic wastewater in the lacustrine zone of the reservoir. However, temporal variability often exceeded spatial variability. The factor analysis indicates that basin geology, anthropogenic stress and agricultural applications simultaneously act vital roles in deciding the reservoir water quality. Based on similarity of water quality parameters, cluster analysis grouped all the nine sampling sites into three clusters of high, moderate and less polluted sites. Correlation analysis also indicated that multiple sources influence the reservoir water quality during all the seasons. Based on BIS and WHO values, the calculated water quality index (134–158) indicates that water of the reservoir is not fit for human consumption, while the trophic state of this reservoir is moderately-eutrophic to eutrophic. However, with precaution, this aquatic body seems to be suitable for aquatic life and fish growth. The overall water quality deterioration of this reservoir indicates a strong need for development of a regular monitoring system for implementation of an effective management system to safeguard human and environmental health.

淡水在决定生态环境，公共卫生和社会经济发展方面具有重要作用。这项研究分析了印度Mettur热带水库地表水水质的时空变化，以确定其水是否适合人类消费和水生生态系统。因此，2018年在九个采样点（包括水库的河流，过渡带和湖滨带）的9个采样点（季风，季风和季风后）进行了季节性监测21个水质参数。研究揭示了空间变化，这是由于工业部门的投入和水库湖区的生活废水。但是，时间可变性通常超过空间可变性。因子分析表明，盆地地质，人为压力和农业应用同时在决定水库水质方面起着至关重要的作用。基于水质参数的相似性，聚类分析将所有九个采样点分为高，中，低污染点三个集群。相关分析还表明，在所有季节中，多种来源都会影响水库水质。根据BIS和WHO的值，计算得出的水质指数（134-158）表明该水库的水不适合人类消费，而该水库的营养状态为中度富营养化至富营养化。但是，经过慎重考虑，这种水生生物似乎适合水生生物和鱼类生长。