The book Ganga: A Scientific Study is based on an Integrated Research Programme carried out by 14 Universities located in the Ganga Basin sponsored and funded by the Envioronment Research Committee and The Ganga Project Directorate, Ministry of Environment & Forests, Government of India, New Delhi. The Ganga, one of World's major rivers, has been venerated as the holiest and is bound with countless beliefs and faiths especially in India and adjacent countries. Its water has traditionally been regarded as an inexhaustible gift of nature. Recent experiences do not, however, warrant such a complacency. The water resources are strained to a non-sustainable level due to rapid population explosion, urbanisation, development of agriculture, industry, livestock and power production in the Ganga basin. The hydrobiological quality of water has deteriorated and yet no concise, valid supporting evidence was available in a comprehensive manner covering the entire river. This book is an attempt towards this direction. For the first time a picture of the Ganga is available with its physico-chemical and biological charateristics, the severe pollution stress and causes to which its water is subjected to, the contents and quality of water and possible remedial measures. An account of algae including pollution sensitive and tolerant species, besides bio-indicators is available. A possible modelling exercise has also been included. A microbiological assay and the bacteria present in the river water is also given. This book, in short, is a synthesis of what the Ganga is at present in respect of its hydrobiology, pollution load, and some aspects of hydrology.