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Binwa is a perennial hill stream of the Western Himalayan region of Himachal Pradesh. During the present investigation, four observation sites based on altitudinal differences were selected, i.e.,Kharli(S₁), Baijnath (S₂), near Chobin (S₃), and Triveni (S₄) and water samples were analyzed for physico-chemical and biological parameters for one year (Mar.2011-Feb.2012). Water temperature, water current, dissolved oxygen, turbidity, T.D.S., electric conductivity, total Hardness, phosphate, and nitrate had played an essential role in determining the variations in planktonic and macroinvertebrate fauna of the stream.Species diversity indices such as Simpson, Shannon and Wiener, and Margalef’s diversity index of macroinvertebrates were worked out for all the observation sites. Based on the comparison of physico-chemical parameters of water samples with different standards prescribed for drinking water, water quality index for four stations calculated. Similarly, EPT taxa (Ephemeroptera, Plecoptera, Trichoptera) measured, and EPT index computed. The water quality of the stream deteriorates downstream from head to mouth due to different types of anthropogenic interferences. The findings revealed that stream has no pollution at S₁, while it is oligotrophic from S₂toS₃and meso-oligotrophic at S_4.