Assessment of water quality in surface waters of the Fayoum watershed, Egypt

This paper presents the first assessment study of the surface water quality in the Egyptian Fayoum Governorate (Province). A total of 42 water samples from irrigation and drainage canals as well as Lake Qarun were collected. Major ions, (semi-)metals, nutrients, salinity and microbiological parameters were examined. The results showed that the highest salinities and highest concentrations of Na⁺, K⁺, Ca²⁺, Mg²⁺, SO₄^2-, Cl⁻ and δ¹⁸O were recorded in Lake Qarun due to up-concentration by evaporation. The highest concentrations of Al, Ba, Cr, Co, Cu, Ni, Fe and Mn were recorded in drainage waters. Tracking the fate of contaminants through sources–sink pathways helped to determine the potential sources of pollution. The highly impacted sites were located close to point sources of pollution such as sewage water treatment plants. Water used as drinking water supply has higher levels of Al and it can be harmful. High levels of microbiological contamination were recorded in irrigation and drainage waters, which therefore might cause water-borne diseases. Improper disposal of sewage or on-site sanitation tank overflowing into these waters is the main cause of microbiological contamination. Drainage and irrigation waters generally have high salinities resulting in soil salinization and degradation. Lake Qarun, a closed saline and alkaline lake, acts as the reservoir for left-over drainage waters. The results show that the lake has a self-cleaning system where most of the (semi-)metals carried by drainage waters are totally adsorbed on the lake sediments. Therefore, Lake Qarun is playing an important role in the environmental balancing in the Fayoum Governorate.