Monitoring water quality and eutrophication phenomenon of Azad Dam using Iranian Water Quality Index and Carlson's Trophic State Index

Water reservoirs have an important role in providing water for drinking and agriculture. It is necessary to protect these resources. This study was conducted to determine water quality of Azad Reservoir (Kordestan-Sanandaj) based on Iranian Water Quality Index (IRWQI) and Carlson's Trophic State Index (TSI). Sampling was carried out at five stations during different months in 2015-2016. Results showed that trophic status of Azad dam was mesotrophic based on chlorophyll-a parameters and eutrophic to hypertrophic based on other variables (TP, SDD and DO % at bottom layers). Mean of Carlson's Trophic State Index represented mesotrophic state (high quality) at Azad dam. Based on IRWQI, water quality of dam was classified as excellent quality. Although, mean of indices indicated the suitability of this lake for drinking and agriculture activities but due to declining water quality and increasing trophic level in some months, it is necessary to apply appropriate management strategies for maintaining water quality in the reservoir.