The lower catchment of Jia Bharali river basin and adjoining areas defined by the Arunachal Himalaya towards north, Brahmaputra river towards south, Jia Gabharu river and Ghiladhari river towards west and east respectively, is characterized by a network of foothills fed rivers and numerous static water bodies linked to fluvial activities. The surface water regime is primarily monsoon dependent, although the trunk channels receive significant contribution from ground water during lean season. This study presents a comprehensive assessment of surface water quality of the area based on analysis of six datasets representing thirty five point sources and three consecutive years (2008 – 2010). The physico- chemical parameters show variable spatial and temporal relationships. The major ion contents show the trend Ca>Na>Mg>K while anion composition follow the trend HCO3>Cl>SO4>>PO4>NO3 in both the wet and the dry season. With respect to the physico – chemical parameters, the surface water sources of the Jia- Bharali catchment and adjoining area are found to be suitable for domestic, agricultural and industrial use.
