The Seybouse is the second most important river in Algeria, it has a catchment area of about 6500 Km² hosting nearly 1.5 Million inhabitants. The river is managed by five dams with a total capacity of 400 million m3. In this catchment area there are important intensive agricultural and industrial activities. The main parameters of general water quality were studied in January and February 2022. The contents of nutrient salts (nitrates NO-3, nitrites NO-2, ammonium NH+4, phosphate PO-43) and organic matter (dissolved organic nitrogen DON, dissolved organic phosphorus DOP) were monitored at three stations, a station located at the mouth of Seybouse, a station at the mouth of oued Meboudja and a station located in chebaita Mokhtar during the month of January and February 2022. The waters of the Seybouse are highly polluted by mineral nitrogen (12.94 mg l-1) and by phosphates (1.16 mg l-1). At the mouth, the Seybouse appears to function as a domestic sewer with an N/P ratio often close to 13. The abundance of dissolved organic matter (DON: 91.7 mg l-1) and (DOP: 2.26 mg l-1) increases the pollution of the receiving shoreline and aggravates the dysfunction.