The present investigation deals with the analysis of important water quality parameters (pH, DO, and BOD) of Tuirial river (in vicinity of the Tuirial Hydel Project) in Mizoram have been analysed for a period of two years, i.e. from January 2008 to December 2009. The findings revealed that pH of water ranged from 7.19 at Site 2 during winter season of 2009 to 7.95 at Site 3 during rainy season of 2009; DO content of water ranged from 6.2 mgL-1 at Site 4 during rainy season of 2008 to 8.1 mgL-1 at Site 1 during winter season of 2008; BOD content of water ranged from 0.2 mgL-1 at Site 1 during winter season of 2008 to 1.2 mgL-1 at Site 4 during rainy season of 2008. The results indicate that all values are within the prescribed limit of water quality standard laid down by various scientific agencies like B.I.S, U.S.P.H and W.H.O. Successive increase in BOD content of water from Site 1 to Site 4 (upstream to downstream) showed cumulative effect of sewage discharge and marked increase in values at Site 3 and 4 may be due to discharge of sewage containing more organic matter.