Barges loaded with mountains of coal glide down the polluted Mahakam River on Indonesian Borneo every few minutes. Viewed from above, they form a dotted black line as far as the eye can see, destined for power stations in China and India.

A coal rush that has drawn international miners to East Kalimantan province has ravaged the capital, Samarinda, which risks being swallowed up by mining if the exploitation of its deposits expands any further.

Mines occupy more than 70 percent of Samarinda, government data show, forcing entire villages and schools to move away from toxic mudslides and contaminated water sources.

The destruction of forest around the city to make way for mines has also removed a natural buffer against floods, leading to frequent waist-high deluges during the six-month rainy season.

And despite the 200 million tonnes of coal dug and shipped out of East Kalimantan each year, its capital is crippled by frequent hours-long blackouts as the city's ageing power plant suffers constant problems.

Farmer Komari, who goes by one name, has lived in a corner of Samarinda half an hour from the city centre since 1985 and used to get by growing small amounts of rice and breeding fish.

But the mines have poisoned the water used in his fields and small ponds, he says.

"The rice is basically grown in poisonous water," said the 70-year-old, standing among his paddies, ankle-deep in brown sludge near the bare, one-room wooden shack where he lives with his wife.

"We still eat it but I think it's pretty bad for us," he says, adding that the water makes his skin itch.

Along with 18 other farmers, Komari has filed a civil suit against government officials, blaming them for contaminating their water sources and allowing rampant mining.

They are not seeking compensation, instead asking the government to oblige a coal company next to their homes to decontaminate the water and provide health services.

'Cronies have done this to Samarinda'

Udin, who owns and drives a rental car and was born in Samarinda 30 years ago, said the city today has been transformed.

"When I was kid, my home was a jungle with orangutans and so many different colourful birds. But now it is bleak," he said.

According to Jatam, a group representing communities affected by mining across Indonesia, the root of the problem is obvious -- local officials have been lining their pockets with bribes from companies in exchange for granting them permits to mine.

"A bunch of cronies have done this to Samarinda. We call them the mining mafia," said Merah Johansyah from the group's Samarinda branch.

Jatam and Indonesian Corruption Watch recently reported a case to the country's anti-graft agency, alleging an Indonesian company, Graha Benua Etam, in 2009 bribed Samarinda's former energy and mining department chief in exchange for a permit.

They say at least four billion rupiah ($340,000) was handed out in corrupt payments, and that some of the money flowed to a former mayor for a political campaign.

The company could not be contacted for comment.

Bribes are being paid for more than just permits, Johansyah said.

He said they also help companies mine in areas they are not supposed to and avoid obligations such as consulting communities and carrying out environmental impact assessments.

Law enforcement, often a problem across the sprawling archipelago of more 17,000 islands where power is heavily decentralised, is also lax.

Campaigners say that companies have ignored their legal obligation to fill abandoned deep pits once their activities are complete. More than 10 people, including seven children, died between 2011 and 2012 from falling into these holes, according to local media reports.

Coal mine destruction spreading

This grim picture of Samarinda is a far cry from what it once was -- a lush jungle with orangutans and exotic birds, many native to Borneo.

It is a common story across the world's third-largest island, which was once almost entirely covered in trees but has now lost around half of its forest, according to the WWF.

Like in the Amazon, the rainforest on Borneo acts like a sponge, soaking up climate change-inducing carbon from the atmosphere.

A recent report from NGO the World Development Movement warned the coal rush is spreading to better conserved parts of Borneo, such as Central Kalimantan.

The forest in that province is currently almost untouched but companies such as Anglo-Australian BHP Billiton have plans to begin mining for coal.

BHP said that any development it carries out in Kalimantan "will be subject to detailed environmental and social impact assessments".

Despite the destruction, Borneo continues to attract nature lovers from around the world to see the oldest known rainforests on the planet and its more than 1,400 animal species and 15,000 types of plants.

But environmentalists warn there might not be much left to see if the environmental devastation continues at the current pace.