A 22 km stretch through Delhi causes most of the Yamuna's pollution
The Yamuna, a goddess to Hindus and the water supply for some 57 million people, runs clean for hundreds of kilometres from its Himalayan glacier. Then it reaches Delhi, where a 22 km reach, under 2% of its length, contributes roughly 80% of all the pollution it carries.
India's longest Ganges tributary, and the second largest by discharge, the Yamuna rises at the Yamunotri Glacier on the Bandarpunch peaks of Uttarakhand. It covers 1,376 km and drains about 366,223 square kilometres, some 40.2% of the whole Ganges basin, before meeting the Ganges at Triveni Sangam in Prayagraj, where the Kumbh Mela draws vast crowds every 12 years. Hindus revere the river as the goddess Yamuna, also called Yami, daughter of the sun god Surya and sister of Yama, lord of death.
For roughly 200 km the young river cuts south through the Lower Himalaya and Shivaliks past gorges, rock benches and terraces. Its biggest tributary, the Tons, actually carries more water than the main stem and joins near Dehradun. Downstream the Chambal, Sindh, Betwa and Ken add their flow. The Sarsuti, a stream that now feeds the Ghaggar near Pehowa, is thought to be an abandoned Yamuna channel, left behind when crustal tilting nudged the river eastward.
Human demand is enormous. The river supplies more than 70% of Delhi's water, and of the roughly 4 billion cubic metres drawn each year, 96% goes to irrigation. A dam at Tajewala, built in 1873, fed the Western and Eastern Yamuna Canals toward Haryana and Uttar Pradesh, and the Hathni Kund Barrage now diverts water into both. So much is taken that in the dry season long stretches between Tajewala and Delhi go dry. Between the Yamuna and the Ganges lies the 69,000-square-kilometre Doab, famous for basmati rice.
The upper 375 km, from Yamunotri to the Okhla barrage, stays reasonably clean as far as Wazirabad in Delhi. Below it, 15 drains empty untreated or poorly treated wastewater into the 22 km run to Okhla, which generates nearly 80% of the river's pollution. Further inputs from the Hindon near Noida leave the channel little more than a sewage trickle until the Chambal revives it at Pachnada. A national Yamuna Action Plan has been running since 1993.
Source: Yamuna
