The present study evaluates various physico-chemical parameters and presence of phytoplanktons, invertebrates and fishes in the Asan river water due to effluents released into it by some industries at Selaqui in Dehradun district of Uttarakhand. Two sampling sites, S1 and S2, reference and impacted, respectively, were selected for determining the impact of pollutants on the characteristics of the water, phytoplanktons, invertebrates and fishes. The main alteration in impacted site observed were change in pH, decrease in dissolved oxygen, biological oxygen demand, chemical oxygen demand, and increase in free CO2, turbidity, hardness etc. The number of aquatic animals decreased due to the discharge of effluents and pollutants. Several control measures are needed to check the pollution of river water caused by the discharge of effluents from industries.