Application of Water Quality Index for Quality Zoning

Aims of the Study: The physical, chemical and biological characteristics of Karaj River (near the city of Tehran, Iran), has been studied to evaluate the suitability of its water for domestic uses. Materials & Methods: Samples of water were collected from various localities before, in and after Karaj Dam Lake and were analyzed based on needs for Water Quality Index (WQI) calculation. In this study, WQI were calculated for the best and the poor condition for quality zoning determination of Karaj water quality. Results: Comparison of water quality index in different sampling stations of Karaj River in different years showed that the water quality of this river was better in 2008 compared with years 2007 and 2009; however ANOVA analysis showed no significant difference between the data in these years (p <0.05). Conclusions: The range of water quality was different from medium to good (WQI=50-100), so this water can be used for domestic uses after suitable treatment.