Water quality assessment of Maroon Dam Lake using WQI index

Continuous monitoring and evaluation of surface water quality is necessary to protect the global ecosystem and human health. One of the most critical ways to estimate water quality is the WQI method. In order to check the water quality of the Maroon Dam lake located in Khuzestan province (15 km from Behbahan city), five sampling stations were selected at the inlet, outlet and inside of the lake. Sampling to measure the water temperature factor (with intervals of five meters by five meters from the surface to the bottom of the lake) and other factors such as dissolved oxygen, pH, biochemical oxygen demand, total phosphorus, total nitrogen monthly and from the surface to a depth of 60 meters (with distances of 20 meters by 20 meters) were carried out from October 2014 to September 2019 and finally the WQI index was calculated using qualitative parameters. The results of this study showed that the trend of changes in WQI index in different months of sampling in different stations in the quality class was medium to relatively good and the range of changes of this index was calculated between 49 in June to 66 in October. The depth measurement of temperature showed that in the lake behind the dam thermal stratification was created in spring (0 to 20 meters), summer and autumn (0 to 40 meters), but in winter, there is no such difference between surface and depth. According to the evaluation of the WQI index values of the reservoir water, it is suitable for all kinds of drinking purposes for domestic animals, agricultural purposes and raising resistant species of fish.