A COMPREHENSIVE WATER QUALITY REVIEW OF RIVER YAMUNA WITH SPECIAL REFERENCE TO WATER QUALITY INDEX IN THE HIMALAYAN REGION OF INDIA

India with 4% of fresh water resources is facing a dual challenge of water scarcity and pollution. Several rivers in India originate from Himalayan systems and forms the basis of Indias Economy. River contamination and diminishing water quality is reducing populations accessibility to clean and safe drinking Water. As one of the significant perennial tributaries of The Ganga Water systems, River Yamuna passes through the heartlands of thegreat North India Plains sustaining cities, feeding millions. Since Yamuna passes through major urban settlement it is heavily polluted with untreated industrial waste, sewage, domestic waste making its way into the river. The study presents a comprehensive reviewof the water quality assessmentsof theriver Yamuna with special reference to Water Quality Index based on severalhydrological parameters. Based on the levels of contamination the whole stretch of Yamuna from its source (at Uttarakhand) till its confluence with Ganga (at Allahabad) has been divided into 5 segments. While all the lower stretches depict high to very high pollution levels, the upper segment of the river in the Himalayas show good water quality. Water quality parameters of river Yamuna depict that BOD, DO and COD levels are not in range of permissible limits in Delhi segment but it falls under permissible limits range in Himalayan segment. Other than these parameters, ammonia, TKN and other organic and inorganic matters fall under the desired standards in Himalayan region of Yamuna.