The first chapter introduces the importance of rivers to human civilization, and in return at present, the river systems are on the verge of irreversible degradation, especially in underdeveloped and developing countries. This chapter vividly discusses the research gap part, which is the need for health assessment of Indian rivers, especially the rivers of the Terai; an interface zone between Siwalik Himalaya and the vast northern floodplain. In an immensely diversified country like India regarding physiography and human activities, it’s a highly complicated task to provide a holistic RHA protocol that will be capable of assessing rivers of all types. It needs robust testing and assessment throughout all types of rivers dissecting such diversified terrain and carrying the imprints of different degrees of human alterations and this study can be recognized as the stepping stone towards that. Among all rivers flowing through the Terai part of West Bengal, India, the authors choose the Mahananda System since it carries the imprints of the third largest urban centre of West Bengal that is Siliguri. This chapter also briefly pointed out the methodology part which comprises assessing the hydro-morphological, hydrochemical and hydrobiological assessment of the Mahananda System.