Nearly 200 industrial establishments in the Mekong Delta's Long An Province are dumping thousands of cubic meters of untreated wastewater every day into the local rivers.
Studies by the Department of Natural Resources and Environment show that most industrial parks in the area are not equipped with wastewater treatment plants, or even a filtering system.
The provincial government has ordered parks without treatment plants to stop operations, but they have refused, despite being fined many times over the past couple years.
This has severely polluted waterways in the area, including the southern's major river Vam Co Dong.
Many of the factories produce animal feed or process seafood.