Rivers flowing through the central part of Kerala viz. River Periyar, River Muvattupuzha, River Chitrapuzha and River Kadambrayar were selected for the present study. Twelve sampling stations representing all the four rivers were analyzed during the monsoon seasons for two years (2018-2019)for temperature, pH, dissolved oxygen (DO) concentration, biochemical oxygen demand (BOD), chloride ion concentration (Cl) , total alkalinity (TA), acidity, total solids (TS), Carbon dioxide (CO2), phosphate ([PO4]3−) and total hardness (TH) using standard methods. For assessing the level of mercury contamination sampling was done from ten selected sampling sites; from surface water, river sediment and plant samples of riparian area, and analyzed using Direct Mercury Analyzer. Among the water quality parameters all the physico-chemical parameters were found within permissible limits of water quality standards suggested by different agencies. While the analytical results of the assessment of mercury contamination in water, sediments and plant tissues indicates that there is noticeably high mercury pollution load in rivers from industrial areas of Ernakulum especially Eloor - Edayar industrial area. It can be attributed that the water pollution in these rivers is due to anthropogenic interference especially industrial activities.