Background: Using available water resources, protection and monitoring of water resources is essential and vital. The aim of this study was to investigate the changes in water quality in Lake of Kalan Malayer Dam in Hamedan province during the year 2017-2018.
Methods: Using GIS software and land use maps, sampling locations in the dam lake were selected. In samples was carried out on 5 occasions, pH, EC, Ca, Mg, Cl, SO₄, PO₄, NO₃, TDS, TSS, DO, BOD, COD, TOC, Turbidity and concentration of common pesticides used in the area were measured.
Results: The results showed that according to WHO guidline, turbidity in May and electrical conductivity, BOD and COD in all sampling times, limit the consumption of drinking water. The average concentration of BOD and COD was higher in the primary stations and decreased from the average concentration in the lake and stations near the dam wall, that be related to the discharge and route of pollutants upstream of the river, which increases the amount of biochemical and chemical oxygen demand. Nutrient concentrations (NO₃, Cl, SO₄ and Na) in all samples were within the allowable range determined by WHO.
Conclusion: Water in winter was of better quality due to increased river flow and water stored behind the dam, lowering the temperature and reducing agricultural activities.