The main objective of this article is to assess the impact of industrial activities on the water quality of the Cau river and to identify the major industrial sources of pollution and their environmental consequences. The impact of industrial effluents on see earlier correction was investigated on 12th November 2016 by collecting water samples at 4 sites along the Cau river from Son Cam to Cau Tra Vuon in dry seasons. COD, BOD5, and 6 heavy metal concentration inside these samples including As, Cd, Cu, Fe, Pb, Zn were analyzed. Analyzed results reveal high levels of pollutants when Cau River receives industrial waster water
high levels of COD and BOD5, at 3 sites (Hoang Van Thu, Cau Gia Bay, Cau Tra Vuon), and high levels of Fe, Pb and Zn at 2 sites (Cau Gia Bay, Cau Tra Vuon). The results show that the Cau river water quality in this section does not meet the standard for aquaculture (A2 limit of 08/2015/BTNMT). The result also shows the negative impacts of industrial wastewater from paper mill, ore mining, Iron and Steel Industrial Park, Lu Xa metallurgical Industrial Park, etc. These sources of wastewater directly pollute the Cau river and change its water quality. Therefore, the protection of the Cau river must include adequate treatment of the wastewater produced in the area, as well as the construction of wastewater treatment plants for major industries in the area.