International Science Community Association International Research Journal of Environmental Sciences 14 4 2025 10 22 Spatio-Temporal assessment of water quality and metal pollution in the Chathe and Intanki Tributaries of the Dhansiri River, Nagaland, India 12 19 EN Angel D. Deva 1 Department of Chemistry & Research Centre, Scott Christian College (Autonomous), Nagercoil-629003 (Affiliated to Manonmaniam Sundaranar University, Tirunelveli), Tamil Nadu, India Celin T. Sumitha 2 Department of Chemistry & Research Centre, Scott Christian College (Autonomous), Nagercoil-629003 (Affiliated to Manonmaniam Sundaranar University, Tirunelveli), Tamil Nadu, India Raj G. Allen Gnana 3 Department of Chemistry & Research Centre, Scott Christian College (Autonomous), Nagercoil-629003 (Affiliated to Manonmaniam Sundaranar University, Tirunelveli), Tamil Nadu, India V.S. Patil 1 Department of Microbiology, Lal Bahadur Shastri College of Arts, Science and Commerce, Satara-415002, Maharashtra, India S.V. Patil 2 Department of Botany, Lal Bahadur Shastri College of Arts, Science and Commerce, Satara-415002, Maharashtra, India Ao Samuel 1 Department of Physics, Kohima Science College, Kohima, Nagaland, India Thisa Vevosüh 2 Department of Physics, Kohima Science College, Kohima, Nagaland, India Kacchara Chetan 3 Department of Physics, Kohima Science College, Kohima, Nagaland, India > Research Paper 2025 8 27 2025 10 22 This study evaluates the spatio-temporal variations in water quality and metal pollution in the Chathe and Intanki tributaries of the Dhansiri River, Nagaland. Six sampling sites were selected along a gradient from upstream forested zones within Intanki National Park to downstream urban and semi-urban areas near Chümoukedima. Water samples were collected during winter (January) and summer (June) and analyzed for physicochemical parameters and trace metals. The Water Quality Index (WQI) and Metal Pollution Index (MPI) were applied to assess overall water quality and heavy metal contamination. Results revealed that WQI values (37.95–42.66) indicated poor to very poor water quality across all sites, with significant spatial variation but no statistically significant seasonal differences. MPI values ranged from 0.693 to 0.928, reflecting the presence of metal pollutants at all sites, with Site 6 consistently showing the highest contamination. Spatial variation was more pronounced than seasonal variation, underscoring the influence of local anthropogenic pressures such as agricultural runoff, wastewater discharge, and land use changes. As the first systematic study on these tributaries, which have remained largely unexplored in previous research, the findings provide critical baseline data for future monitoring. The study emphasizes the need for site-specific management strategies, stricter pollution control, and continuous monitoring to safeguard the ecological and socio-economic importance of these rivers. Copyright@ International Science Community Association