Water is vital for humanity. It remains the main constituent of living beings and the indispensable element for every form of life. Water resource pollution is characterized by microorganisms, chemicals, or industrial waste. It can concern rivers, water bodies, brackish waters, rainwater, dew, snow, and polar ice. The industry also has a close and even vital relationship with water. Industrial activities put pressure on the resource in terms of removals and pollution. To this end, the primary purpose of our research is to carry out a hydrochemical study of the waters of the lower valley of the Mafragh (far north-east Algeria) to identify and determine the pollution that threatens this river. Water sampling was done in March 2022 at the level of the upstream, center and downstream of Oued Mafragh to analyze several physico-chemical parameters, determining the pollution level. The results show significant and very high pollution with several determined origins, such as industrial, urban, and agricultural, which requires strict control and monitoring of the location of a treatment plant so that the water from this Oued can be used in many areas of life.