Water is a vital resource, but its quality is increasingly threatened by human activities and climate change. In Algeria, and particularly in semi-arid regions, surface water faces growing pressure from urban and industrial discharges, while scientific data on its quality and irrigation suitability remain scarce. The objective of this study was to evaluate the physicochemical characteristics and irrigation quality of surface water in six areas of northeastern Algeria, thereby filling a critical knowledge gap in a region where monitoring is limited. Thirteen sampling sites were analyzed for physicochemical parameters, water quality indices (WQI, SAR, Na%), and the water pollution index (WPI). Results revealed elevated concentrations of chloride, sulfate, and sodium in some stations. Two hydrochemical profiles were identified: a calcium-magnesium-chloride-sulfate type in most stations, and a sodium-potassium-chloride-sulfate type in Oued Charef and Oued Meskiana. The WPI indicated that 70 % of stations had low pollution, while 95 % of samples were excellent to good for irrigation. The global irrigation index (IRR) proved to be a reliable tool for assessing irrigation suitability, with more than 50 % of surface waters classified as appropriate for agricultural use. This study provides new baseline data on surface water quality in north-eastern Algeria, highlighting the urgent need for continuous monitoring, wastewater treatment, and sustainable agricultural practices to mitigate salinity and pollution risks in water-scarce environments.