A fire crackles along the banks of the Yamuna River: a cremation of a young mother, struck by a car while she was fetching water.

The stench of the river engulfs the sad assembly.

Before the hissing funeral pyre, floating down the river, white blocks of what looks like detergent appear like icebergs. It is 95 degrees in Delhi this night. This is chemical waste from factories that have sprung up across the city, manufacturing leather goods, dyes and other goods.

Downstream, the living reside along garbage-strewn banks.

A colony of shacks sits beneath the Old Iron Bridge, a vestige of the British colonial era. Its tracks trundle trains across the Yamuna, on the northern edge of the city. Like the Ganges, the Yamuna is sacred to Hindu believers. The faithful dangle garlands from the bridge's hulking girders and pitch ashes and money from its railings.

Steps away from his hut, 8-year-old Ravi, wearing only his underwear, dives into the contaminated water to retrieve their offerings. He clambers out, tugs on some clothes and, magician-like, pulls the coins he's tucked away for safekeeping from his mouth.

Delhi is about a third of the way down the 855-mile Yamuna River. Its source is the Yamunotri glacier, crystal-clear water from the Himalayas. But by the time it moves down the eastern edge of India's capital, it exits as the dirtiest river in the country.

For the past 18 years, Mohammad Zamir, a laundry man and father of four, has beaten rags against rocks. Washing remnants used on factory assembly lines, he stands up to his knees in the filthy water from dawn to dusk.

But Zamir, 38, says he's not worried about his health. "No," he says matter-of-factly, "the water looks black because of the shadows falling on it. I have no problems. Neither do our elders, who are nearly 80 and did the same work."

Yet according to the Central Pollution Board's most recently published water quality data, from 2011, by the time the Yamuna exits the city, it is lethal. The water contains a concentration of 1.1 billion fecal coliform bacteria per 100 milliliters of water. The standard for bathing is 500 coliform bacteria per 100 milliliters.

"That is the reason why this stretch of the Yamuna is called dead," says noted environmentalist Manoj Mishra. "Because there is no life here. There cannot be life here. There's nothing here."

Mishra walks along the banks, explaining that upstream, huge amounts of water are channeled off to irrigate farmlands, drastically reducing the river's flow. Just before the Yamuna enters Delhi, millions more gallons are siphoned off for Delhi's drinking water, shrinking the flow even further.

"A river that does not flow is no river," Mishra says. He sweeps an arm toward the stagnant water. "And as you can clearly see, there is no flow here. It's a toxic cocktail of sewage, industrial waste and surface runoff. Absolutely unfit for any use whatsoever."

Architect Pankaj Vir Gupta says no fresh water replenishes the entire 13-mile stretch through Delhi. Gupta runs a project with the University of Virginia to rejuvenate the Yamuna, and says only waste flows into this span of the river.

"In fact," he says, "the only time in the year when the river is moderately clean is during the monsoon when fresh rainfall falls directly into the river."

Unbridled urbanization is partly to blame. Over the past two to three decades, new arrivals, drawn to the capital by a liberalized economy and a dearth of opportunities in their own villages, settled wherever they could. About a third of Delhi's 17 million residents live in settlements that are officially illegal — and are not connected to any municipal sewer service.

When this underserved population openly defecates, Delhi Water Board CEO Keshav Chandra says the waste finds its way into drains that dump directly into the river. "The infrastructure to take care of this incoming population could not cope up with this," he says.

But that's not the only thing that hasn't kept up. The Yamuna is a dumping ground because polluters get away with it.

"You will find every law in Delhi, but no enforcement," says Delhi Water Board member R.S. Tyagi, with a wry laugh. He says there's lax enforcement of laws against illegal dumping of arsenic, zinc and mercury, against pouring raw sewage into storm drains and against the illegal cultivation of crops on the contaminated floodplain.

The Yamuna is administered by no fewer than two dozen different local, state and national government agencies, Tyagi says, and that in itself is a problem. "In this way," he says, "nobody can be accountable."

The Yamuna supplies about a third of Delhi's drinking water, which gets channeled to a reservoir in the northernmost corner of the city before the river becomes toxic.

Architect Gupta says residents of the unauthorized slums must depend on "private tankers, bore wells and a water mafia" for their drinking water. "That can't work," Gupta insists, and argues for the need to "democratize the water supply" of Delhi.

But even the condition of drinking water that comes out of the tap has given rise to a lucrative private industry of home water filters, which are relatively expensive. Mishra says families who can't afford them inevitably fall sick.

"That's how their life is," he says. "And it is highly irresponsible, and in some ways, even criminal. But the solution lies in getting the river back."

Some are trying to do exactly that.

An experiment funded by the Delhi Development Authority and overseen by a team of scientists has a small section of the Yamuna floodplain thriving. Concrete high-rises loom on the periphery of this nature reserve, an oasis on the north edge of a noisy and polluted city.

This butterfly and bird-filled wetland replicates the flora and fauna of what was here 100 years ago, according to field biologist Mohammad Faisal. He says thousands of migratory birds, 20 species of fish and 35 species of dragonflies have returned as a result of nurturing this conservation habitat over the past five years.

"Wetlands act as a nursery for the river itself," he says.

Artist and activist Ravi Agarwal says this 450-acre biodiversity park in the floodplain is the beginning of an overdue healing.

"Nature and the city become two oxymoronic words — they don't sit with each other. Earlier, they used to flow into each other, and there was a beautiful coexistence," he says.

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