The Saptakoshi River is a major wetland of Koshitappu Wildlife Reserve. It is running North South nearly at the center of the reserve. It provides prime wetland habitat to Ganges River Dolphin, Platanista gangetica; Gharial Crocodile, Gavialis gangeticus; Mugger Crocodile, Crocodylus palustris different species of tortoises, fishes and water snakes. Similarly, aquatic avian species both local and migrants are seen in the River. Moreover, this wetland is not only major sources of water for wildlife but also irrigation services to local people. Some ethnic communities like Majhi, Sardar, Jhangar, Tharu, Rai, Limbu, Musar, Bote, Mukhiya, Bantar, Godhi etc. involved in fishing for their livelihood.
About 4-5 hours boating from Raja Bas to Koshi Barrage, visitors can enjoy by seeing water and forest faunas. Eastern dam of Sapta Kohi River was broken due to flooding in 2008. Many wetlands were damaged and destructed at that time. High rate of Siltation in Sapta Koshi River, fish poisoning, haphazard fishing, causing wetland habitat destruction, is an emerging issue. In active participation of local communities upstream and downstream watershed management plan should be prepared and implemented.