Comparative Study of Water Quality Indices in Shahid Rajaee Dam Reservoir (Sari, Mazandarn Province)

Dam reservoirs are commonly used for a variety of purposes including flood control; supplying drinking, irrigation, and industrial water; marine transport; fish culture; and recreation. It is therefore, essential to safeguard water qulity in order to ensure the sustianble and economical operation of dmas. This study was conducted to identify the relevant water quality indices for Shahid Rajaee Dam Reservoir (Mazandaran-Sari) and compare them based on abiotic (some of the physico-chemical) and biotic (Chlorophyl-a, Shannon, Saproby indices, microbes, and fungi) parameters. Sampling was carried out at four stations during different months in 2012-2013. The Water Quality Index was investigated using seven physicochemical parameters; the TSI trophic index based on nutrients, water turbidity, and chlorophyll-a; and the Shannon and Saproby indices. Maximum monthly values of TSI were obtained in July and August (eutrophic status) while minimum values belonged to September and February (oligotrophic status). Based on, water quality in the reservoir was classified in the “good” category in all the study months. Water quality assessment using Shannon and Saproby indices showed that July and August had the lowest water quality (moderately to highly polluted). The maximum fungal colony and coliform counts were observed in August and September at all the sampling stations. The study revealed that more reliable and comprehensively illuminating results can be achived if, especioally in the case of drinking water supplies, water quality investigations are conducted using both biotic and abiotic parameters. Overall, it is recommended that all human activities around the dam or upstream river tributaries be controlled and checked during the warm months of the year in order to prevent eutrophication, algal blooms, microbial activities, and organic phosphorus loading.