This story is part of a special National Geographic News series on global water issues.

Even as pollution levels in the Ganges River continue to rise, recent legal rulings may offer up a new defense of the sacred waterway.

Last month, the Allahabad High Court, in the northern state of Uttar Pradesh, ordered the closure of more than 100 tanneries that pour tons of toxic chromium into the Ganges each year in the industrial city of Kanpur.

The ruling was the latest in a series of decisions by the court that have stopped giant construction projects in the Ganges floodplain and mandated the construction of new waste treatment plants in cities along its banks.

"It's the great achievement of my life, if it succeeds," says public interest attorney Arun K. Gupta, who took part in the litigation.

Three sacred rivers meet at Allahabad: The Ganges, born of clear Himalayan tributaries that first trickle and then rage down from India's border with Tibet; its sister, the Yamuna, which shadows the Ganges to the west before curving past Delhi and the Taj Mahal to join her; and the mythical Saraswati, ancient and invisible, which is said to run beneath the earth.

Only the Saraswati reaches Allahabad in a pristine state.

In the dry season the Ganges limps into town, dark with sewage and industrial waste. Pollution is heavy even at the height of the monsoon. The Yamuna arrives burdened by raw sewage from New Delhi, some 1,900 million untreated liters (502 million gallons) each day.

These waters meet at one of the holiest spots in Hinduism. Allahabad, Persian for "Settled by God," plays host every dozen years to the Kumbh Mela, the biggest gathering of humanity on Earth, when tens of millions of pilgrims come to wash away their sins at the confluence of the three rivers.

A recent visit to the Triveni Sangam, as the confluence is called, found hundreds of pilgrims walking under a blazing white sun to bathe and to collect water in plastic jugs to take home. S.P. Pandey, a recently retired judge, directed a visitor toward a spot in the expanse of water. "That, there, is the Sangam."

Even an untrained eye can see just where the two temporal rivers meet, before the Yamuna is subsumed into the Ganges: The Yamuna has a bluish cast; the Ganges is a turbid yellow.

Duality?

There is a strange duality in India's approach to its holy rivers.

The Ganges is unmistakably holy, made so by thousands of years of religious practice. At the same time, India treats the river as a septic tank.

Past rescue efforts have failed due to fatal gaps in planning, implementation, and administration, said professor B.D. Tripathi, of the Center for Environmental Science & Technology at Benares Hindu University.

A new cleanup plan for the entire 416,000-square-mile (1 million-square-kilometer) Ganges River basin is gathering steam, but it will take decades and cost tens of billions of dollars, according to the World Bank.

Meanwhile, important changes are happening on the ground, thanks partly to rulings by the Allahabad High Court that:

* Squashed both a planned eight-lane, 650-mile(1,050-kilometer) expressway and giant housing projects destined for its floodplain.

* Forced construction of more than a dozen waste treatment plants in Kanpur, Allahabad, and Varanasi.

* Stopped the excessive diversion of Ganges water to upstream irrigation projects and cities.

* Last month ordered the closure of tanneries in Kanpur.

These orders, if properly carried out, will change decades-old practices, costing developers and factory owners many millions of dollars. They could also harm the bureaucrats and politicians who often feed off public works projects and big industrial polluters.

Court orders are one thing. Implementation is another, cautions Rakesh Jaiswal, of the Kanpur-based NGO EcoFriends. "The court has directed the government not to release untreated sewage and industrial effluent into Ganga [the Ganges] on several occasions," he said, "but it's still happening."

Pollution's Problem

Pollution has only worsened on the Ganges during the years that Gupta and others have been battling in the courts, according to data seen by National Geographic News.

Upstream of the confluence, where the Salori sewage canal meets the Ganges, biochemical oxygen demand—a measure of organic pollution—increased from an average of 3.5 milligrams per liter to nearly 5 mg/l between 2006 and 2011. The government limit is 3 mg/l.

Coliform—an indicator of human and animal waste—reached a jaw-dropping average of 15,000 mpn* per 100 milliliters at Salori in September 2010, falling to 8,875 mpn/100ml by the time it reached the confluence a few miles away.

The government limit for coliform in rivers is 500 mpn/100ml. At no time in 2010 were coliform levels at the confluence, where millions bathe each year, lower than 5,500 mpn/100ml.

Upstream in Kanpur, chromium levels were more than 100 times the official limit.

In 2013, the Kumbh Mela will again come to Allahabad.

By that time, Arun K. Gupta says, nearly 60 percent of the 70 sewage canals that currently dump human waste into the river at Allahabad will have been capped. Those many millions of believers, Gupta said, will indulge in a cleaner, healthier holy river.