The Ganges River is worshiped by a billion Hindus and a water source for 400 million, but the stress and pollution have turned it into an environmental disaster.

Known as “Mother Ganga,” Hindus believe that a dip in the river absolves a lifetime of sin. Here in the northern town of Devprayag where the head of the Ganges is formed, the waters appear crystal clear, drawing villagers to perform ablutions.

But as the 1,500 mile long river snakes its way through the densely populated plains of north India, so much water is sucked out that it’s nearly impossible to maintain a healthy, clean flow. Still, thousands immerse themselves in the river every day, some bottling the water to drink and use for crops.

Further downstream in the industrial city of Kanpur. Tannery workers haul chemical-soaked buffalo hides into huge drums and dump their run-off into the river. Industrial waste and sewage pour in from open drains and clouds of foam float on its surface.

In the ancient and holy city of Varanasi, Hindu pilgrims seek spiritual purification and cremate their dead along the river banks. Many pray that followers will keep the Ganges clean.

As the river widens it curves southwards, collecting debris as it passes through thousands more villages and cities. In the metropolis of Kolkata, people bathe and brush their teeth next to mounds of garbage.

The Indian government has proposed a number of efforts to restore the Ganges, but the $3 billion clean-up plan is badly behind schedule. An estimated 4.8 billion liters of sewage flows into the river every day. Less than a quarter of it is treated.