Abstract: Assessing quality of water resources and having accurate quality information are required for their management. The Chahnimeh reservoirs are the major source of drinking and agricultural water in southeast of Iran, and evaluation of their water quality is necessary. The water quality index (WQI) is the most important indicator expressing the qualitative condition of water in simple terms, without mathematical or statistical complexity. Therefore it was used in this descriptive, cross-sectional study of the first Chahnimeh reservoir based on sampling during the four seasons in 2016. Eight sampling stations were selected in the reservoir to determine six variables (nitrate, nitrite, dissolved oxygen, electrical conductivity, hardness, and pH). Despite spatial and temporal variations and fluctuations in these parameters, the results demonstrated that water quality in the reservoir is good. Moreover, the values for all measured parameters, apart from electrical conductivity, were within acceptable – i.e., recommended – ranges. Generally, considering the WQI values, water quality in the middle part of the lake was better than at its margins. Given the increasing importance of the Chahnimeh reservoirs, continuous evaluation and a water quality monitoring programme are required.
Keywords: Water resource, water management, physico-chemical parameters, monitoring