Water quality assessment of Wadi El‐Rayan Lakes, Egypt: Utilizing pollution indices and indicator bacteria

Abstract The Wadi El‐Rayan depression, a protected area in Egypt's Western Desert southwest of Cairo, contains two man‐made lakes that serve as reservoirs for agricultural wastewater while supporting fisheries and irrigation. This study assessed their water quality, including heavy metals and microbiological parameters, using the Water quality index (WQI) and heavy metal pollution indices to evaluate suitability for aquatic life. Microbiological analysis found that total coliform, fecal coliform, and fecal streptococci levels at most sites were within acceptable limits for aquatic organisms. The Upper Lake demonstrated fair water quality (WQI = 52–78), while the Lower Lake was of medium quality (WQI = 50–66) and exhibited higher total dissolved solids. Heavy metal pollution was also more pronounced in the Lower Lake. The primary threat to the Upper Lake is effluent from the El‐Wadi Drain, which degrades water quality through intensive agricultural discharge. The Lower Lake faces additional ecological stress from a shrinking surface area due to agricultural encroachment and sand dunes. To prevent further degradation, immediate actions, such as optimizing water allocation and establishing a robust water quality monitoring program for the lakes and the drain, are critical. This study underscores the potential for effective water resource conservation and calls for an integrated effort among policymakers, industries, and communities to ensure a sustainable water future.