Its 22-km stretch from Wazirabad barrage - where Yamuna enters Delhi - to Okhla, is less than two per cent of the river's total course but accounts for over 70 per cent of its pollution.
"Yamuna through Delhi is not a river. The definition of a river is that it must have life and how you measure life is that it must have capacity to dissolve oxygen. And the dissolved oxygen content in Yamuna as it passes through Delhi is zero. Which means its dead... it just hasn't been officially cremated," said Environmentalist Sunita Narain.
The government has so far spent over Rs 5,500 crore on cleaning the river as part of Yamuna Action Plan. Many sewage treatment plants have been set up including 17 in Delhi. But these plants can only treat less than half the total waste pumped in each day.
But future plans are massive. The Delhi Jal Board (DJB) 2031 sewerage master plan envisages Rs 25,000 crore to be spent to upgrade the sewerage network.
The recent Yamuna march that saw thousands marching from Vrindavan towards the national capital brought the issue back into the spotlight. Union Water Resources Minister Harish Rawat promised to set up a committee to study the feasibility of setting up a parallel channel so that the sewage can be dumped there instead of the river. He also promised that an additional 125 cusecs of water will be released at Okhla.
The United Nations has already declared it a dead river. But many in India are still hoping that Yamuna can someday be a flowing river through Delhi.