The Lower Seybouse Plain in northeastern Algeria is undergoing rapid and unregulated urban development, particularly in the industrial sector, resulting in asignificant environmental degradation. Thus, the current study aimed to assess the surface water quality of the Oued Seybouse (Annaba) and to investigate various water pollution parameters. In February 2023, three sampling points were examined in the Oued: Djoinou, Sidi Salem, and Bouhamra. The analysis focused on key physico-chemical parameters indicative of water pollution, including pH (hydrogen potential), electrical conductivity, biochemical oxygen demand (BOD₅), nitrates, nitrites, and chlorides. Increases were recorded in pH and electrical conductivity, along with elevated levels of nitrates, nitrites, and chlorides, as well as a rise in BOD₅, indicating the presence and biodegradability of organic matter in the wadi. These changes contribute to the contamination and rising pollution levels in the wadi, rendering the water increasingly unusable and in urgent need of biological, chemical, and physical treatment.