This book provides in detail assessment of the health of Mahananda river, an important head water river system in the Darjeeling Sub-Himalayas which is getting altered rapidly with the pace of human interference. It covers all aspects of river health monitoring through an effective method combining geospatial analysis and field measurements for the assessment of the hydromorphological, hydrochemistry, and hydrobiological quality which indicates that it is neither maintaining its overall fluvial characteristics and functions, nor can quickly replenish, supporting local biota and sediment transport. This book also identifies the factors responsible for existing health condition and suggests target-oriented restoration measures for the sustenance of river health essential for restoring the hydro-ecological balance of one of the most degraded river. The book can be utilized as reference materials by academics, practitioners, and decision-makers for the health assessment of other river basins.