When it rains in the shantytown of Tudor Shaft, the streets pool with orange water that smells like vinegar. Experts say the water contains radioactive minerals and has killed all aquatic life in a nearby river.
Tudor Shaft takes its name, and its troubles, from an abandoned gold mine.
It's just a fraction of the toxic but long-overlooked legacy of South Africa's most famous industry. Mining accounts for 17 percent of everything South Africa produces, and the country is the world's fourth biggest exporter, sitting on a mother lode that runs for miles from Johannesburg into the countryside.
Social campaigners, preoccupied first with overthrowing apartheid and then with raising living standards for a badly neglected black majority, are now waking up to the environmental cause. The effects of mining are the focus of parliamentary debate and newspaper stories. But no one is yet taking responsibility or funding a cleanup that would probably put a dent in profits.
Johannesburg literally sits on a gold mine. Flat-topped heaps of mined earth are backdrops to skyscrapers and bridges. FNB Stadium, the main arena in last year's World Cup soccer tournament, sits at the foot of a mine dump. Johannesburg's amusement park is called Gold Reef City and features a ride that plunges into a mine shaft.
The city of 3.2 million grew out of the gold bonanza discovered in the early 1900s. Nowadays, whenever a mining company removes one of the 270 dumps around Johannesburg to reprocess the waste, heritage advocates complain that the city is losing a piece of its patrimony.
The worst environmental effects are felt in places like Tudor Shaft, 25 miles (40 kilometers) from the city. Here, Patrick Mkoyo's children run barefoot, their feet tinted orange from contaminated sand. He says they sometimes come home with rashes or breathing difficulties.
"They are not OK here, but I don't have a choice; I have no other place to stay," says Mkoyo, 35, as he stirs a family lunch of cornmeal porridge in his immaculately kept shack.
The doctors tell him they don't know what is causing the children's medical problems. But Chris Busby, a professor from Northern Ireland's University of Ulster, thinks he has the likely answer.
In December he tested the soil around Mkoyo's shack and found it contained at least 32 times the amount of radioactivity allowed by government regulators. Busby prepared the report for the Federation for Sustainable Environment, a private Johannesburg group working to bring the toxic water issue to public attention.
According to Terence McCarthy, a minerals professor at Johannesburg's University of Witwatersrand, radioactivity comes from uranium traces in mined rock which lies in dumps until rain flushes it into the ground and river systems.
Acidic water dissolves and liquefies metals in the mining rock, including uranium, says Anthony Turton, a professor of environmental management at University of the Free State. Liquefied uranium, toxic and radioactive, flows out of the mines, he says.
The water can be so acidic that it eliminates river wildlife, Turton says.
The problem hasn't yet reached Johannesburg itself, but one mining basin in the city has already overflowed, and one of the next to overflow is under the city center, experts say.
Aside from Tudor Shaft, other parts of the city's outskirts are feeling the damage of toxic mine water, entering rivers and communities at an increasing rate with heavy rain in recent months, says Mariette Liefferink, chief executive of the Federation for Sustainable Environment, a private group. Yellow-tinted grass, orange mud and lifeless rivers plague sections of western Johannesburg, as well as Soweto, one of South Africa's largest townships.
No studies have been done on how exposure to the water affects health, Liefferink says, but scientific reports have documented its destructive effects on the ecosystem, soil and water.
Peter Cronshaw, a mineral economics consultant for Tegritas Financial Services, said the cost of a cleanup would accelerate South Africa's already declining mining industry, particularly for smaller companies, but it wouldn't affect the global gold industry. The country's diminishing supply of gold means an increasing number of derelict mines.
South Africa produced 206 of the 2,652 metric tons of gold mined globally in 2010, says Philip Newman, the research director of London-based GFMS Ltd., which researches precious metals. Its production ranks fourth behind China, Australia and the U.S.
While abandoned mines everywhere produce toxic runoff, the problem is most threatening in South Africa, Turton says. Johannesburg, unlike most mining cities, is densely populated and an economic hub. On top of that, Turton says, the mining industry in South Africa has gone largely unregulated.
The apartheid rulers relied on the steady stream of income from booming gold prices to offset international economic sanctions over the treatment of blacks. "There's been little oversight from government, and mining companies have done nothing about it _ for 120 years they've had a party," Turton said.
Environmental NGOs, or non-governmental organizations, got off to a late start on mining because past governments, while aware of toxic mine water's impact, sought to keep the public in ignorance, he said.
"Under apartheid, there was absolutely no tolerance of any NGO activity at all," Turton said. "When there was activity, it had to do very much with bringing down the apartheid state."
Now, the post-apartheid government is under pressure to hold companies accountable, while the companies deny responsibility.
"Most of the toxic water that flows into rivers come from abandoned mine sites which have no owners and thus the responsibility to put into place water pollution control measures lie with the state," says Nikisi Lesufi, senior executive of the Chamber of Mines, an industry group.
Cronshaw, the consultant, says most gold mining companies don't even have titles to the mines that are the source of toxic water.
"The mining companies say: These mines were here long before we were and they weren't our mines; our companies are subsidiaries. The government allowed them to do this, therefore it has got to sort it out," Cronshaw says.
AngloGold Ashanti Ltd., the South African mining giant, says it expects the government will "lead the process of national coordination" on handling toxic water and that the company already contributes to pumping water from one defunct shaft outside of Johannesburg. In a statement, spokesman Alan Fine said AngloGold mine dumps do not contain much groundwater.
Mining company Anglo American tracks water quality and is devising a national water-cleansing strategy for itself, spokesman Pranill Ramchander said in an e-mail.
In the U.S., mine companies have been under tight regulation for decades. R. Larry Grayson, professor of energy and mineral engineering at Penn State University, recalls that a U.S. mine he worked at in the 1970s was fined $10,000 on the spot because of one dead fish found.
Sputnik Ratau. the government's spokesman on water and environmental affairs, says dangerous mine waste is a "high priority," but acknowledges it was not given serious attention until the government set up a committee to study the issue in September.
"Acid mine drainage is toxic water, and if it flows into rivers, it obviously contaminates rivers and underground waters, which become not a healthy source of drinking for humans, animals, plants _ all living organisms," he said.
"Because the necessary steps were not taken from day one," Ratau said, South Africans "are now reaping what you would call the misfortune of the benefit that we had from the legacy of mining in this country."