Several years ago, I took a journey with my wife and baby daughter to my mother-in-law’s childhood home, a forest village in the southwestern Indian state of Kerala. As any Keralite will tell you, Kerala is the lushest, most watery corner of India, a skinny coastal strip where hundreds of tributaries merge into broad, winding rivers before finally flowing into the Arabian Sea. My mother-in-law’s village is named Manimala, for the river that provides its reason for being.

My wife spent her childhood summers in Manimala, and all her stories seemed to center on the river: the old stone steps that villagers descended to board a ferry or take a bath; the neighbors fishing or washing elephants; the flotillas of flowers that drifted downstream after monsoon gales. I’d been cultivating a fantasy that our own daughter would spend her summers on these banks. But when we arrived in Manimala, I was shocked: The great river had become a trickle. In a few places it had pooled into puddles big enough for people to wash their clothes. Otherwise it was barren, the stone steps now leading to a gouged-out ravine of pale boulders baking in the sun.

“What happened to the river?” I asked.

“Sand mafia,” my wife’s cousin Thambichan answered.

The Manimala, Thambichan explained, once had a sandy riverbed that in some places was 30 feet deep. The sand acted as an aquifer, regulating the river’s flow. But sand is also a crucial ingredient in concrete, and India is urbanizing at a speed and scale virtually unmatched by any country in history. Apartment towers, highways, bridges, skyscrapers, metros, dams: Each of them swallows unimaginable helpings of sand. It could line the rivers, or it could form the cities that were rising everywhere alongside them, but it could not do both at once.

“No one listened when we warned of the dangers of sand mining,” my wife’s uncle Shaji told me. With nearly all the sand removed from the river, the water table had dropped for miles around. When the monsoons came, the water whooshed away as quickly as the rain fell. The ordinary wells ran dry, so people drilled tube wells deep into the earth; now some of those were running dry, too. The local rice paddies were long gone. Along the river’s route, several major bridges faced collapse, because the loss of sand had weakened their foundations.

When Indians use the term “sand mafia,” they’re talking about the whole range of people who profit from illegal sand mining: the local laborers; the budding capitalists who own the trucks and earthmovers; the genuine mobsters who, in some places, organize the miners and offer extra muscle; the suppliers who act as middlemen between the mafias and the real estate developers; the police and officials who take bribes from any or all of the above. And the politicians — sometimes, it’s rumored, even chief ministers of major states — who take their cut and maybe even run sand-mining operations of their own. The McKinsey Global Institute calculated that the hundreds of millions of Indians migrating from villages to cities require up to a billion square yards of new real estate development annually. Current construction, according to one estimate, already draws more than 800 million tons of sand every year, mostly from India’s waterways. Though no reliable numbers are available, all the people I spoke to in India assumed that much of it is taken illegally.

As I came to know Manimala, it became clear that the river had mostly been mined by the villagers themselves. You could see the evidence in many of the new houses nestled among the rubber trees and coconut palms. Some were made of concrete, large and sprawling and brightly colored: pink, neon yellow, fire-engine red. A few had heaps of sand out front to be used for concrete or plastering for new wings and other renovations.

One evening, I sat with Saji P. Thomas, a slender, energetic former sand miner with a small mustache, in front of his new house. He told me he started sand mining around 2002, to raise money for a new business. (He now runs a small cosmetics factory.) It was possible then to mine sand legally, but Thomas, like many others, didn’t bother with hard-to-obtain permits at first; he mined only at night to evade the police. They worked in groups of four or more, he said. Some would pilot the rowboat and the others would dive as deep as 15 feet to fill their baskets with sand. The loads were awkward and heavy. “We’d make a staircase out of tree stumps,” he said. “But the danger was we’d slip off a step and almost choke to death underwater.”

At the river’s edge, another team would load the sand into a truck. Sometimes, Thomas said, the truck driver would get a call that the police were on their way, and they’d scramble to finish loading the truck and flee; any bribes the authorities might demand could cut deep into their margins. “There are policemen who have built beautiful houses thanks to sand mining,” he said. His previous job, at a bank, paid 400 rupees a day, roughly $5. A good night’s work mining sand earned him 2,000 rupees. So Thomas kept at it. “To distract myself, I’d fantasize that I was a businessman in a nice car.”

The work did sound terribly dangerous. But the most striking detail in Thomas’s story was not about the mining itself, but about the attitude of his neighbors who lived at the river’s edge. Back when there was plenty of sand, trucks came day and night to load up at the river. But to get access they usually had to cut across the property of the town’s riverfront homeowners, most of whom would collect a toll of 150 rupees from each truck that passed. Now that sand mining has wiped out the groundwater, those same homeowners have to hire different trucks — tankers — to bring them drinking water, at more than 1,200 rupees a trip. The sand was gone, and gone with it were the river, the groundwater and even the tolls. All that was left was a question, one that haunts river communities all over India: Why would any village so willingly accept such paltry gains for certain catastrophe?

More than half the apartments built during India’s construction boom can be found in the New Delhi metropolitan area. One of the highest concentrations of these apartments is in Greater Noida, a suburb that lies between the two most sacred rivers in Hindu lore: the Yamuna to the west, and the Ganges to the east. Both rivers are heavily mined, and it’s easy to see where all that sand goes.

Greater Noida has come to embody the shiny, walled-off vertical India of the future. Amid seemingly endless colonies of newly constructed concrete apartment towers, you can enjoy one of India’s finest golf courses and the country’s only Formula One racetrack, as well as a shopping mall that tries to simulate the city of Venice, complete with gondola rides. Among all the well-guarded high-rise clusters, you can still find the remnants of 124 agricultural villages, which 40 years ago were the only habitation in this place: fragmented fields of mustard and wheat, an odd absent acre picked over by a stumbling herd of goats.

Greater Noida was created in 1991 and is administered not by a mayor but by a chief executive. The idea was to transform the farmland just outside booming New Delhi into an industrial hub that would attract job-creating factories. (Noida is an acronym for New Okhla Industrial Development Authority.) Instead, according to local accounts, the authority sold much of the farmland to private developers for 10 or 30 or even several hundred times what they’d paid the original landowning farmer, and Greater Noida became a reservoir for population overflow from New Delhi. The few industries that did come to Greater Noida rarely hired villagers, preferring instead to bus in better-educated workers from other northern cities. Young jobless village men and migrant laborers turned to petty theft, and Greater Noida saw a wave of muggings and carjackings. Some high-rise residents began to treat their complexes as fortresses, driving out only in the daylight.

Naushad Khan, a 37-year-old former sugar-cane farmer with a boyish smile and a boxer’s physique, seized the opportunity presented by the construction boom to enter the entrepreneurial class. As a teenager, he joined and then expanded his elder brother’s digging company, excavating the foundations for new developments and selling the sand they removed. Now, capital in hand, he was starting his own development, an “eco-friendly” luxury condo tower, on the outskirts of Greater Noida. He had turned sand into money, and now he would turn that money right back into something concrete.

Construction, Khan told me, was an extremely competitive business, which he counted as a blessing. “If you want to succeed, then there should be a good, strong rival against you,” he said when we met at his freshly built office. I asked him if sand mining was ever dangerous. By way of answering, he asked an assistant to fetch his pistol. He set it on the table between us as a kind of conversation piece, next to the tea and cookies. It was Indian-made, long-barreled and hefty-looking. He laughed when I asked if he’d ever had to use it. “Many times,” he said. “Tens of times. Scores of times.” He was quick to add a clarification: He’d fired it only for safety, shooting in the air to ward off suspicious people or if the atmosphere was wrong. That sort of thing.

The last time I saw Khan was at an overwhelmingly well catered wedding reception he hosted for his nephew inside a hangar-size tent. Parked inside the entryway was an immaculate white Audi Q5, presumably a wedding gift. Greater Noida had worked out well for him, Khan acknowledged. He always took sand legally, he said — he was quite insistent on this point — and now he could help provide a comfortable standard of living for an extended family with over 40 members. Amid the festivities, Khan seemed almost giddy with pride for all he had achieved.

One afternoon I took a drive around Greater Noida with a local farmer named Vikrant Tongad, a sly young man with pointy shoes and a thick pompadour who wanted to show me what had happened to the surrounding rivers. For long stretches of our trip, the only people we saw on the roadside were hawkers waving glossy brochures, trying to lure us to open houses. Between the high rises, dust storms whipped the empty fields. Every billboard we passed was an advertisement for a high-end condominium. One featured, alongside the usual list of perks, a flirty photograph of the Bollywood star Deepika Padukone and an unsurpassable slogan: “Nothing Left to Desire.”

Why don’t Indians just shift to other construction materials? In part it’s because concrete is cheap, strong, easy to use and highly versatile. In part it’s cultural: Building a house out of brawny concrete has come to be viewed by many as a matter of prestige. “They feel that beauty is a beast,” the architect B.R. Ajit told me ruefully. The law encourages this tendency. One environmental lawyer explained to me that the Indian building code recognizes a house as a house only if it’s made from specific heavy materials — concrete included. “If you use that criterion,” he said, “the president’s house is not a house.”

Now, as we drove past mile after mile of unfinished apartment towers, a city for ghosts, all I could think about was the tons of river sand locked within. Many of the condos in Greater Noida are bought as investments by Indians living abroad, and sometimes buildings are left empty by owners who have no intention of taking residence. In other cases the developers run out of money midconstruction or are halted by legal disputes, leaving bare concrete shells for years on end. Some buyers who actually do intend to move in are left waiting helplessly for the keys to apartments they paid for long ago.

Finally we arrived at the floodplains of the Yamuna. We stopped to survey the deep pits and fresh tracks where sand miners with earthmovers had been working under cover of night. Similar pits dotted the land as far as the horizon, some large enough, I later learned, that children used them as cricket grounds. The mining has shifted the course of the Yamuna, destroyed animal habitats, damaged crops and threatened the purity of local groundwater, and it may be causing buildings to sink. But it’s especially difficult to single out the effects of sand mining on the Yamuna because the river is troubled in so many different ways. The truth is that with the exception of a couple of months during monsoon season, by the time the Yamuna River reaches Greater Noida, there is no river at all.

Tongad walked me down to the banks, and we saw something that looked like a river: There was liquid in the riverbed, and it flowed in a particular direction. But it’s an illusion. Less than 150 miles north, nearly every drop of the Yamuna is rerouted to provide water for the city. The liquid that flows in the Yamuna riverbed alongside Greater Noida consists of every variety of urban waste: factory refuse, slaughterhouse runoff, sewage. If you walk right up to the water, what you’ll find are swirls of oil, clouds of white chemical foam, animal parts, floating turds. I never spent time next to the Yamuna without getting a headache for the rest of the day. And yet old traditions die hard. I saw the Hindu faithful still dipping their idols into this supposedly sacred sludge. Families still cremate their dead on the ghats along the fetid banks.

Our last stop was a shop that appeared to sell cellphone chargers. In fact, the chargers were a ruse; it was really an unlicensed wine shop. In the back room Tongad introduced me to a sand miner named Jagbir Nagar. He was a thin man, around 60, dressed head to toe in white, and with him were several young men from the village, all seated around a hookah.

Nagar is the sarpanch, or head man, of his village in Greater Noida. He also shares an earthmover with a team of five or six others that they use to mine sand from the floodplains. Together, he said, they can take as many as 100 truckloads of sand a night, some of which is used for local projects and the rest of which is mostly picked up by truckers from the desert state of Rajasthan. (If that sounds like sending coals to Newcastle, it’s not; desert sand is too fine and rounded to make strong concrete.)

I asked Nagar if he was worried that the mining might adversely affect the quality of the local water. It was a question I had an immediate interest in, given that we were at that moment drinking glasses of what they’d told me was unfiltered local groundwater. Nagar grunted in the negative and looked like at me as if I were an idiot.

Tongad answered for him. “They’re happy with mining,” he said. “Groundwater depletes: No problem. River is dying: No problem.”

“People are selfish,” a younger man agreed.

“The miners say, We dig a hole, and the next year the river comes and fills it again,” Tongad said. “So what’s the problem?”

I had often encountered this attitude in India. Everything is rigged, the argument goes. How can you expect us not to seize whatever meager leavings we can? It’s not as if we’re carjackers — we’re taking sand! From what used to be our own land! It’s difficult to convince people who for generations have taken local sand for granted that, like passenger pigeons a century ago, something they had thought of as infinite is now dangerously finite. It’s difficult to tell people who have always been able to take sand according to their needs, and who now have seen outsiders come in and derive great profit from it, that sand is in fact a critical natural resource that needs to be protected.

“If the police come, do you fight them?” I asked Nagar.

“If there are a lot of police and only a few men, then we run,” he said. “If the police are few and the men are many, then we get into it with them. We fire shot for shot.”

Nagendra Prasad Singh, the district magistrate in charge of enforcing the law in Greater Noida, is a serious man, built like a pillar, with a push-broom mustache and a slight twitch in his right eye. He came from a farming family but earned a graduate degree in physics before entering the Civil Service. His previous posting was in Shamli district, which also lies on the Yamuna, and it was said that he put a complete stop to sand mining there — the first I had heard of any such success anywhere in India.

When he came to the New Delhi suburbs, Singh quickly began running night raids on illegal miners, seizing dozens of truckloads of sand and imposing fines of tens of millions of rupees on the violators. At his office in Noida’s Sector 27, I asked him if the raids had posed any danger for him. “Have you read the Gita?” he asked. “The soul never dies. The energy may change shape, but the soul never dies. With that kind of confidence, I don’t think anybody can shoot us.”

Singh said he had been fighting the sand mafia since 1999, when he was the city magistrate in Haridwar, a pilgrimage town that marks the spot where the Ganges emerges from the Himalayas. There he learned all about the sand trade from a tiny but stubborn community of activist Hindu monks called Matri Sadan. Their leader, a dreadlocked former chemistry teacher now called Swami Shivanand, moved to Haridwar in 1997 to devote his life to praise of the Ganges, but his prayers were disrupted by the incessant work of the sand mafia. The swami’s objections to mining in the Ganges were largely religious, but as a chemist he was also keenly attuned to the earthly costs.

Together Singh and Swami Shivanand set their sights on a businessman named Ponty Chadha, who ruled the sand trade across the state of Uttar Pradesh. He was also the distributor of many Bollywood blockbusters, a real estate magnate, the state’s main liquor baron and a philanthropist focused on special-needs children and had close ties to the chief minister of Uttar Pradesh. Singh and the monks managed to get Chadha’s sand-mining license revoked, which left the trade to the motley assortment of smaller players that dominates it to this day. (Chadha died in 2012, when a real estate dispute with his brother Hardeep escalated into a gunfight.)

Singh eventually realized that law enforcement alone would not be enough to stop the theft; arresting the leaders of many smaller mafias may be an even greater challenge than ousting a big gangster like Chadha. Now his focus is on harm reduction. Central to his argument is an exasperating fact: There really is enough sand in the rivers and offshore to meet India’s demand for concrete and plaster, at least according to many conservationists. In some cases sand mining can even be beneficial. An oversilted river — a river with too much sand — is also prone to flooding and changing course, and strategic sand mining can help keep it on track. The catastrophes occur only when specific, vulnerable stretches of river are overmined. There’d be no problem if the construction industry mined only from river sites with a carefully identified surplus of sand.

Existing laws on sand mining should be adequate to regulate the trade, but as is so often the case in India, the laws are toothless. In 2013, for example, India’s National Green Tribunal — a special fast-track court for environmental violations — issued a blanket ban on all river-sand mining without environmental clearance. But according to the environmental lawyer Rahul Choudhary, almost all of the applications are granted clearance. Rejections usually occur only because of incomplete paperwork.

Singh has a different approach. The first step, he said, is to secure genuine environmental clearances, based on field studies. Next, offer leases to mine on those cleared sites by public auction, with strict parameters on the dimensions of the lease and the depth of excavation permitted. There is no honor system; surveyors must map the site and then fix posts into the riverbed to physically block the leaseholders from mining beyond the designated zone. When the mining begins, the magistrate and his officials make frequent unannounced inspections of the sites and weekly video recordings to monitor the depth of sand. The magistrate must also hold regular meetings with townspeople in mafia-prone areas. “Most important,” Singh said, “is the awareness of the people who are living along the river, so that they may feel like a watchdog, that the river’s interest is their own interest.”

It sounded like a smart plan. But it also seemed to rely almost completely on the presence of extraordinarily vigilant magistrates. If a district was unlucky enough to be assigned a corrupt magistrate, or merely one whose interest in sand mining were less intense than Singh’s, the system would fall apart. It was going to be a difficult model to replicate.

I asked Singh if he knew any other magistrates who were taking a similar approach. “I am not in contact with anybody who is doing this,” he said.

Criminality and graft have come to be seen as such incontrovertible facts of life in India that, in my experience, people seldom mind discussing them openly. When I met a young real estate agent named Girish Kasana in the office of his father’s construction company, for instance, he brought a particularly well-informed perspective on the realities of how Indian cities are built. “Everything is corrupt,” he said.

Construction is the business where criminals have the best opportunities to launder the most money, he explained, and a cascade of bribes go “to the topmost levels in the government.” Kasana grabbed a copy of a construction tender on his father’s desk and started furiously scribbling numbers on the back. To get a typical government construction commission, he explained, you pay 6 percent in bribes up front. Then, after the first payment, you pay another 7 percent, half of which goes to the state’s top politicians. The development authority’s junior engineer gets 3 percent. The associate engineer gets 1.5 percent. The senior manager gets 3 percent, and so on — until the total reached an astonishing 30 percent. “When this is given, then almost anyone can be managed,” Kasana said. “This is the system. This is India.”

“The thing to do is to get a job in the authority,” my translator joked.

“This can also be done,” Kasana said. To get a job as a junior engineer, he said, requires a bribe of 10 million rupees.

As I talked to developers about sand mining, I often found myself sympathetic to their explanations. The existing system practically forces anyone who wants to build something to collude in the destruction of the rivers. The sand trade is furthermore sustained by a devilishly inbuilt chain of plausible deniability. Unlike most other categories of mining, where large companies dominate the business, sand mining is executed by an endless array of small, independent, often temporary players, largely working at night and in secret. And each step of the line of production is separated from the rest: The sand moves from diggers to truckers to dealers to builders with each link in the chain knowing as little as possible about where the sand they’re buying comes from or who mines it — for obvious reasons, they don’t want to know. Nameable sand dons like Ponty Chadha are rare. The fragmentation and anonymity of the chain is exactly what allows it to continue with so much impunity.

“I believe in the power of the people,” Singh told me on my last day in the New Delhi suburbs, just before we got into his pristine white Hindustan Ambassador to go talk to the villagers of Jhatta about sand mining. “To stop an illegal thing, first show your intention. If you are a man of integrity, you have to show it, because people never believe you at first. But gradually, gradually, if you succeed in showing them that you have no personal motive, that you are just trying to motivate them in the larger public interest, that you are just doing your duty, then the people become convinced. That’s my experience.”

In Jhatta, more than 100 villagers, all men, all wearing their best starched whites, gathered in a courtyard next to the village temple to hear Singh’s speech. They had covered their chairs with silky white slipcovers and presented the magistrate with a bursting bouquet of flowers. His oration on sand mining drew on every appeal at his disposal, rhapsodizing about rivers, spelling out the science, quoting scripture. When he finished, his deputy led the villagers in a chant: “Illegal mining: We won’t do it, and we won’t let it happen!” (It’s catchier in Hindi.)

It was a compelling speech, and I could see how Singh might convince the villagers of Jhatta, person by person, moment by moment. But of course his adversary is not each villager one by one. It is the systems and values many of us hold in common — the competitive lure of conspicuous consumption, the insatiable engine of development, the universal corruption that fuels it — all of them obstructing any effort to reckon with environmental catastrophe, which has a confounding tendency to manifest itself long after the original gains have accrued.

After the speech, a farmer named Sohan Pal Singh approached me to say that the district magistrate was making too much of sand mining. “For us, it’s a normal activity,” he said. “It’s not such a big deal.” He wanted to show me something outside: Piled against the wall of the courtyard where the meeting was just held was a heap of sand that he himself had helped mine.

I asked him if he planned to stop mining after hearing what the district magistrate had to say. He scowled.

“If the district magistrate told me to stop wearing clothes,” he asked, “should I take off my shirt?”