In recent years, the dredging of navigational channel and resource exploitation in coastal areas have been carried out increasingly. However, the investigation and the environmental impact assessment of these activities have not been done.yet. Early Dinh An - Can Tho navigational channel (the section of Dinh An river, Ben Tre province) has been deposited severely by sediments from Hau River, caused an obstacle of navigation operating. The project to dredging Dinh An - Can Tho navigational channel has been carried out helping heavy ship to travel through easily. Disposal can bury all ecosystems at disposal site and a new ecosystem will be replaced. In this paper, the authors use the environmental impact assessment methods in implementing the project and proposing the environmental monitoring program. Numerical modeling method has been also used to evaluate the current change due to dredging. The results showed that after dredging navigational channel, the environment and ecosystem have been changed not much.