NEW DELHI — As the worshippers descended the slope to the riverbank, dressed in their festival best and carrying offerings, a voice on the loudspeaker repeated: “The water is deep, don’t let go of your child’s hand, don’t let them in the water.”

It was a much-needed warning for the thousands of families in attendance for the four-day Hindu festival of Chhath that ended Thursday (Nov 11), a celebration of the sun deity Surya that involves fasting and making offerings while standing in water.

They needed the warning because the river’s water was, in fact, barely visible, blanketed with a toxic foam of industrial waste and sewage. If you didn’t know better, you could mistake it for the morning after a night of heavy snowfall.

Many worshippers in northern India celebrate the festival at the Yamuna River, a religiously significant tributary of the Ganges that runs through the capital city of New Delhi.

Every year, the festival season of November brings unwelcome reminders of how devastatingly polluted the water and air around the city remain. The Yamuna, one of the main sources of water for Delhi, is so overwhelmed by waste in the 13-mile stretch that cuts through the city that it is highly unsafe for bathing or irrigation.

But the Yamuna’s decades-old problem of pollution gained new prominence in embarrassing fashion this week when the local administration in Delhi tried to scrape together a last-minute cleanup at the festival site. It sent out boats to try to sweep away the foam, laid down bamboo barricades to stop it from spreading and even deployed workers with hoses to sprinkle the river with clean water.

“What are you doing?” a reporter asked a Delhi government worker in a video.

“I am spraying water to kill the foam,” he said.

Yet, none of these shambolic efforts seemed to dent the spirits of the worshippers as they thronged by the thousands to the riverbank — not the foam below, the smog above or the Delhi government’s warnings that the coronavirus that wreaked havoc in the city earlier this year was still a threat.

Their explanation: What’s a little foam in the face of faith?

The families arrived in taxis, traditional sugar-cane offerings jutting out the windows, and they got there packed in the backs of tractor wagons and large trucks. They came in bright saris and in shiny suits. Many walked barefoot, and some carried their own sound systems — with a car battery for power.

“I am not worried,” said Ms Kiran Devi, who had not eaten in three days and would break her fast only when the festival ended with the final prayer. “Once I go in the water, it will be fine.”

Some cleared the foam with their hands, pushing it away to create a little space for their prayers. Others used sticks. The foul odors were inescapable.

Ms Devi arrived for sunset Wednesday, and her extended family of 10 would spend the night by the riverbank to wait for the sunrise worship that is the festival’s culminating event. The women, who made up the majority of those fasting, arranged the baskets of offerings with bananas, coconuts and radishes, and filled the diya lights, small clay lamps, with ghee before lighting them. The men mostly lingered and chatted.

Her brother-in-law, Mr Sonu Prasad, 36, who sells buttons, said he knows what contributes to the pollution of the river: “When I shower, it goes into a small canal, then a big canal, then it goes into the river,” he said.

“It’s a sewer,” Mr Devi’s husband and Mr Sonu’s older brother, Mr Ravi Shankar Gupta, said. “But the sun deity says: ‘Even if you stand in a gutter and make an offering, I will protect you for the rest of the year.’”

“It would be great if they improve it, but even if they don’t, what can we do?” Mr Gupta added, pointing to the infighting over the pollution between the states that the river flows through. “We will still live, and enjoy life.”

One of the reasons the authorities for decades have failed to address the problem of river pollution is bureaucratic red tape and “the multiplicity of agencies” involved, said Mr Avinash Mishra, a top adviser on water and land resources to the government of prime minister Narendra Modi.

“It’s become a volleyball,” Mishra said.

He warned that the country’s water woes, if not tackled with urgency, could have dire ramifications for an already slowing economy.

“The moment the water is contaminated, there is water shortage, which impacts human working days,” he said. “It generates so many waterborne diseases that it will impact your services, your industries, urbanization and the living standards of your population.”

Undeterred by such considerations, the worshippers thronged to the river for the sunset Wednesday, many of them staying the night on the riverbank to catch the sunrise the next morning.

“In society, when someone falls low, when someone grows poor, they stop respecting that person,” said Mr Premchand Jha, who works as a driver. “Here, we give as much respect to the setting sun as we do to the rising sun.”

Ms Devi’s family had come prepared with a rug, a couple of sleeping bags and blankets for the children. Her husband, Mr Gupta, explained that they were staying the night because they wanted to reach the water’s edge to see the sunrise before things got crowded.

“Whoever comes earlier will get a little more from the sun god,” Mr Gupta said. “A little blessing, and maybe a little property.”

As the sunrise neared, the fasting women entered the water and remained knee deep in their final meditation. But there would be no dramatic climax — the sun simply wasn’t visible through the Delhi smog.

“We can’t shine extra light on the sun, we have ruined that too,” said Mr Jha, the driver. “But I checked online. The sunrise is between 6:30 and 6:40. When we see the first glimmer of redness there, then the sun has risen.”

This article originally appeared in The New York Times.