The 'Walk for Yamuna' was undertaken on World Rivers Day, to draw attention to rivers facing severe and increasing threats associated with climate change, pollution and industrial development.
Plans and schemes to save the river have gone down the drain
The Yamuna in Agra is now seen posing a major threat to the historical monuments along its banks including the 17th century Taj Mahal, whose foundation needs constant moisture.
"But in the past two decades, all kinds of pollutants and toxics are freely flowing into the river," said an organiser of the walk, Shravan Kumar Singh.
These could corrode the structure below the main platform of the Taj, he said.
Jugal Kishore Shrotriya, a temple priest and a young green activist, said that the Yamuna, for all practical purposes, was dead in Agra.
"Only garbage, carcasses and sewer flow," he said. "The aquatic life has been decimated. So many plans and schemes to save the river have gone down the drain."
Activists said the free flow of the river has been obstructed by a series of barrages upstream that hold up all the water. What reaches Agra is just waste and sewage.
"The Yamuna Action Plans have made no discernible improvements in water quality. The flow is inadequate. The sewage treatment plants either do not work or are short of resources," said Surendra Sharma of Heritage Society.