India’s booming population and rapidly expanding urban areas have exacted a huge toll on its rivers, which are badly polluted and choked by development. But in cities across India, activists are heading to court to force municipalities and states to take action.

Standing on a small concrete bridge, environmental activist Janak Daftary gestures toward the crowded banks of the Mithi River, which runs through the heart of Mumbai. On one side are garages with heaps of car parts that slope into the river, bleeding paint, metals, and oil into the Mithi, a mere 120 feet wide at this point. On the other side are shanties made of brick, tin, and plastic; metal scrap dealers; and a middle-class housing complex flanked by concrete walls that plunge into the water. Below the bridge, a dark slurry with floating bits of plastic, cloth, and rubber slowly passes downstream, toward the office buildings and construction cranes of Mumbai’s new financial district. “This is how you kill a river,” says Daftary, an engineer who works with Jal Biradari, a water conservation group. Along with Vanashakti, a Mumbai-based environmental organization, Daftary’s NGO prevailed in a case in India’s Supreme Court last August involving the restoration of the Mithi. The top court reprimanded the local authorities for their neglect and directed independent experts to assess measures taken to date and recommend additional remedies to reverse the degradation of the Mithi. India has seen a string of such judicial rulings involving urban rivers in recent years, as the country comes to grips with the widespread pollution that has fouled waterways and with runaway development that has destroyed or damaged wetlands and floodplains. Across major cities, environmentalists and citizens are engaged in prolonged, seemingly intractable battles to clean up local rivers - mainly through legal petitions intended to force authorities to take action or, in some cases, to stop them taking damaging measures, such as constructing concrete flood walls that hem in the river. Some of these battles have been triggered by recent floods and made more urgent by projections of increased extreme rain events and other climate risks.

The sacred Ganges has been at the center of a legal battle focused on the failure of a government plan to clean up the river.

In the technology hub of Hyderabad, activists went to the National Green Tribunal, a quasi-judicial authority, in 2015 to prevent illegal construction near the city’s Musi River. In Chennai, in South India, citizens have petitioned the tribunal to stop pollution of the Cooum River, as well as to ensure proper dredging of a large canal to remove silt and improve flow. In New Delhi, activists have been fighting one legal case after another over the years to keep the floodplain and river bed of the Yamuna, a major tributary of the Ganges, free of myriad developments, including a subway depot and road. And the sacred Ganges, which runs through five Indian states, has been at the center of a legal battle by environmentalists and citizens frustrated by the failure of a government plan to clean up the badly contaminated river. Rivers and streams have borne the brunt of the recent urban explosion in India, a nation whose population has nearly doubled in the last 40 years to 1.35 billion. Unplanned growth has led to the use of water bodies as dumping grounds for sewage and industrial effluent. According to India’s Central Pollution Control Board, 63 percent of the urban sewage flowing into rivers (some 62 billion liters a day) is untreated. In addition, riverbanks, wetlands, and floodplains have been claimed over time by infrastructure, slums, offices, and housing developments - all of which has narrowed natural river channels and distorted flow, greatly reducing the ability of India’s rivers to buffer flooding. It also has taken a toll on biodiversity.

The cost of this abuse has mounted over the years. A study last year linked increasing cases of typhoid, hepatitis, and diarrhea in New Delhi to severe pollution in the Yamuna River, which provides much of the city’s drinking water. Large stretches of the Yamuna, as well as Chennai’s Cooum and Mumbai’s Mithi and Ulhas rivers, are considered dead zones, with oxygen levels too low to support most fish life.

Men search for coins and recyclable items along the banks of New Delhi's Yamuna River. PRAKASH SINGH/AFP/Getty Images

Environmentalists blame the failure of past cleanup efforts on a host of problems: The political clout of industries, contractor-driven boondoggles, weak enforcement by pollution-control agencies, and clashing government departments. The $3 billion initiative to clean up the Ganges, a flagship project of Prime Minister Narendra Modi, must navigate the politics of five states, numerous cities, and multiple central government agencies. Renowned hydrologist Madhav Chitale resigned from the main Ganges cleanup initiative last year partly because, he said, “some people [in the mission] are focused on religious and cultural issues rather than on the technical remedies.” He and others point to the Sabarmati River in Gujarat, Modi’s home state, as an example of sound urban river restoration. For decades, the Sabarmati - which runs through the state capital of Ahmedabad - was just another dirty, seasonally dry river. Then architects gave it a makeover, clearing out the slums along its banks and creating a channel of clear water bordered by a long concrete waterfront. The creation of attractive riverfronts is seen by many as key to mobilizing public support for conservation. But some have criticized the Sabarmati project for focusing on beautification rather than ecological restoration. Water was brought from another river to keep the channel full, and pollution has simply been pushed downstream, said Himanshu Thakkar, coordinator of the South Asia Network on Dams, Rivers & People, a conservation group. “We don’t have a success story yet,” he said. The cost of the damage to India’s rivers was made painfully clear in December 2015, when Chennai experienced severe rainfall that overwhelmed its river and canal network. The region’s small rivers had been extensively manipulated over the years and had lost their floodplains to urban development, says Jayshree Vencatesan, managing trustee of Care Earth Trust. “Unless their flow is managed as a grid, they cannot perform their ecosystem services,” said Vencatesan.

For much of its run, Mumbai’s Mithi River is a glorified sewer serving small workshops, slums, housing developments, and a business center.

The Chennai floods took nearly 300 lives, damaged thousands of homes and businesses, and paralyzed the airport, which is partly built over the Adyar River, all leading to an estimated $3 billion in losses to the city’s economy. The flood brought attention to the assault on the region’s natural systems, with marshland shrinking by 45 square miles from 1980 to 2010, according to a study by Care Earth Trust. The disaster provided new impetus to long-pending cleanup plans for the Cooum River, which had languished for decades. Last year the official Chennai Rivers Restoration Trust obtained environmental clearances for a major restoration project.

A similar disaster unfolded in Mumbai on July 26, 2005 when an unprecedented monsoon deluge drowned the financial capital, killing more than 900 people, damaging a quarter-million homes, and causing an estimated $2 billion in economic losses. This inundation made Mumbai residents suddenly aware of the presence of the Mithi River in their midst. A modest channel that begins in suburban hills, the Mithi winds 11 miles down to the Arabian Sea. For much of its run, the river is a glorified sewer serving small workshops, slums, housing, the airport, and a business center. All were inundated on that fateful day when the conjunction of high tide and extreme rain caused the river to overflow its banks and flood the city.

A restored wetland park on Chennai's Adyar River. VAISHNAVI CHANDRASHEKHAR/Yale e360

Since then, multiple studies have decried the systematic destruction of the Mithi, pointing to a host of assaults: The airport’s runway had been built over the river, narrowing the channel and forcing it into a 90-degree bend, and a new office district had been built on wetlands. One satellite study found that from 1966 to 2005 the width of the Mithi was reduced by almost 50 percent, while mudflats had shrunk by 70 percent. The experts proposed solutions: close polluting businesses and industries, collect garbage, install sewage plants, restore the banks, dredge the river, create a buffer zone, and nurture the mangroves to absorb future floods. Last August, intense rainfall came perilously close to causing another major flood in Mumbai. That same month, the Indian Supreme Court condemned the lack of progress in restoring the Mithi following the 2005 floods. Despite much expenditure, the river is still filthy and continualy encroached upon, most recently by the dumping of debris from construction of a new subway. Municipal authorities have been slow to set up sewage treatment plants, and the few treatment projects underway don’t hew to expert recommendations. The National Environment Engineering Research Institute (NEERI) and the Indian Institute of Technology Bombay had called for setting up as many as 37 small sewage plants along the river, rather than a few large ones - a recommendation the city has so far ignored. “The model from developed countries in which all sewage is taken and treated in one place appears to be impossible here because planning is always far behind population growth,” said NEERI director Rakesh Kumar. In this context, he said, a decentralized approach might work better. Mumbai has taken some steps in recent years, mainly for flood prevention. Municipal authorities have spent S100 million dredging and widening the river at its narrowest points, and the regional planning agency, which controls the last 3.7 miles of the river, has spent millions more removing silt, demolishing encroaching structures, and resettling hundreds of slum dwellers.

The Mithi’s crowded banks point to the social challenges of these cleanup efforts, especially in a city where half the population lives in slums.

But the Mithi’s crowded banks point to the social challenges of these cleanup efforts, especially in a city where half the population lives in slums. Relocating slum dwellers and industries takes time - land must be found, consent obtained, people and businesses shifted. Often people are forced out and homes demolished willy-nilly, as has happened on Chennai’s riverbanks. Rehabilitation sites are usually far away, disrupting community and employment networks. In the neighborhood of Kalina, along the Mithi, residents are furious about having to possibly move to a resettlement complex near polluting oil refineries. Such action seems especially unjust since entities such as the airport and the financial complex have expanded into the river’s flood plain, and they are not being told to leave. “If everyone is to blame, why target the slums?” asked Fayzah Khan, a local resident.