Thane, India - Every morning as the tide ebbs, Pralath Matre dives deep into a filthy creek not far from Mumbai to gather a bucketful of dark sand - a much-needed ingredient for the construction boom under way.

Matre, 42, dives 300 times every day in the 15 metre-deep waters. He earns 800 rupees ($13) a day, but the cost is much higher. The heavily polluted sea has caused infections in his nose, eyes and skin, and affected his hearing.

It's a scene that's playing out not only at this creek, but at dozens of other places around the financial capital of India, where the sand feeds the hunger of construction projects.

Some 10 years ago, industrial waste depleted the fish at this creek. Then fishermen turned to quarrying sand, which is diminishing like the fish.

Pralath Matre, sand diver

"If I don't dive, someone else will for the lure of the gold tucked at the bottom of these waters," Matre, the father of two, told Al Jazeera.

The sand boats - called bauchs - are equipped with long steel rods, a myriad of ropes, and paddles that function like oil rigs in the sea - shifting tentacles from one place to another after having devoured the sand deposits beneath.

"Some 10 years ago, industrial waste depleted the fish at this creek. Then fishermen turned to quarrying sand, which is diminishing like the fish," Matre said.

Sand - inexpensive and abundant - is a treasure to India's builders and the construction industry, which employs some 40 million people.

The sector is also the second largest contributor to India's GDP after agriculture.

'A new Chicago every year'

Prime Minister Narendra Modi's government plans to develop 100 "smart cities" under its "a new Chicago every year" slogan.

But the spike in construction means sand mining, both legal and illegal, will increase in coastal areas, riverbeds, creeks, and rivulets.

To meet this goal, India needs $1.04 trillion of investments in infrastructure.

Modi has visited Japan, the United States, and Australia and hosted Chinese President Xi Jinping to attempt to woo foreign investment.

If his plan is successful, nearly half of Indians - about 590 million - will live in cities by 2030, according to a McKinsey Global Institute report. About 18.78 million urban dwellers, however, will continue facing housing shortages in the meantime.

For builders, it's a big market, but the government's ambitious infrastructure plan has raised concerns.

"The speed at which we are constructing infrastructure is worrying. Do we have enough sand for it?" wondered PR Swarup.

Swarup is the director general of Construction Industry Development Council (CIDC) that guides the government on construction industry-related policy-making.

The boom in construction has led to a high demand for river sand [AP]

"There has to be a substitute to the natural sand."

Swarup said builders should consider using manufactured sand created by crushing rocks.

Illegal sand

The high demand for sand has given rise to illegal mining and involvement of criminal syndicates.

Every year, India creates property worth billions of dollars. In the year ending in March 2014, the country developed assets worth $64.8bn. The next 25 years, analysts say, could see India quadrupling its assets.

"India faces twin challenges," Niranjan Hiranandani, managing director of Hiranandani Constructions, one of India's top real estate companies, told Al Jazeera.

"At the primary level, there is this huge demand for homes, which will create huge demand for natural resources required for construction.

"Add to that initiatives like 'Homes for all by 2022' and you see the second aspect of the challenge. It has the potential to create even larger demand for construction material - sand is no exception," said Hiranandani.

While India consumes 500 million tonnes of legally mined sand every year, according to CIDC figures, industry insiders and conservationists say the number could be several times more if unlawfully mined sand were also included in the tally.

"There is no mechanism to regulate the extraction. Miners are dredging creeks and riverbeds at will," Sumaira Abdulali, a Mumbai-based environmental activist, told Al Jazeera. "That's why I insist builders should disclose the source of the sand."

Abdulali's non-profit organisation, Awaaz Foundation, has been at the heart of the struggle against illegal sand mining in western Maharashtra state.

Litigation by the group forced the government to clamp down on illegal miners. Abdulali has been followed and threatened by the "sand mafia" and members of her organisation have been attacked.

Altering ecology

Environmentalist Sunita Narain, who heads the think-tank Centre for Science and Environment, said a major factor that has sustained the illegal mining of sand is "both economic interests - given the boom in the construction sector, and the vagueness and poor understanding of regulatory provision for sand mining".

FACTBOX

India expects $1.04 trillion investments in infrastructure before 2017

590 million Indians will live in cities by 2030

In 2014, India built assets worth $64.78bn

40 million people are associated with the construction industry

India's housing shortage during 2012-17 to stay at 18.78 million among urban dwellers.

500 million tonnes of legally mined sand used each year

Narain said the Supreme Court and regulator National Green Tribunal had strict guidelines but the government revised them in December 2013.

"However, there is still considerable lack of clarity on part of the states regarding how to regulate sand mining besides all these orders," Narain told Al Jazeera.

Environmentalists say the rampant mining increases river gradient, soil erosion turbidity of water, and depletion of fish, and lowers the riverbed level and the groundwater table.

The natural flow of India's Yamuna river has been altered, and heavy sand mining has changed the course of the Sutlej river in northern Punjab province. The riverbeds of Beas, Cauvery, Ganges, Godaveri, and Narmada, have also been heavily mined.

Attempts by conservationists have done little to stop the trend.

In June 2011, activist Swami Nigamananda Saraswati died after a four-month fast against sand mining on the banks of the Ganges river.

Other activists like Ramdas Ghadegavkar, Pale Ram Chauhan, and Sandeep were killed, allegedly for exposing the nexus between officials and illegal sand miners in the northern Uttar Pradesh and Maharashtra states.

M-sand or UK-model?

Industry analysts say one way to stop illegal sand mining and save the ecology would be the increased use of manufactured sand, known as M-sand.

Real estate tycoon Hiranandani says developers at some construction sites in Pune city are already using M-sand in the form of crushed stone as an alternative, but the long-term effects of using artificial sand has to be monitored.

Officials of the Confederation of Real Estate Developers' Associations of India (CREDAI) - an apex body for private real estate developers in India - told Al Jazeera that builders are worried about the anticipated sand shortages.

They say the time has come to abandon natural sand for its artificial counterpart, if the supply can meet the demand.

"Developers may not mind using the manufactured sand, provided they have assurances on sustainability, durability and availability," Vimal Shah, president of the Maharashtra Chamber of CREDAI, told Al Jazeera.

But, Shah said: "It should be a cost-effective alternative."

Environmentalists worry that M-sand acquired by crushed stones shouldn't be a substitute either.

"Substituting sand mining with stone mining? Both are equal evils," Narain said. "The solution lies in reducing waste and recycling and tapping into our waste stream."

Narain said India should adopt the UK model.

 Indian village's economic transformation

"Around 17 percent of UK aggregate needs are already met from recycled material, while another eight percent is being met with other non-natural material."

As the debate rages, divers like Matre continue to earn a living from sand hidden beneath Mumbai's polluted bodies of water, while witnessing the new construction their labour makes possible dotting the skyline.

"Sometimes I wonder whether divers like me can ever afford to buy these expensive flats," he said.

"Those selling or purchasing it would never understand how it feels to stay inside water, hauling sand and breathing nothing for 45 seconds," he said.

Follow Baba Umar on Twitter: @Babaumarr 

Source: Al Jazeera