On the face of it, the area of grassland on the Witkrans farm outside the Mpumalanga highveld town of Carolina seems as undisturbed as the surrounding veld.
Except for what looks like a gravel pit at one end, the ground is level and stretches for about the size of two soccer fields from the dirt road to the edge of a maize field.
But underneath the seemingly undisturbed surface lies a dirty secret. Evidence of this has appeared in the form of unnaturally clear water seeping from the hillside further down and the dead vegetation along its path.
It is yet another case of acid mine drainage, or AMD, which results from the exposure to air of mining's broken rock and coal residue, and which is carried into streams and rivers by rain and ground water.
The piece of land is the site of an opencast coal mine that shut down some years ago. A rusty gate, a concrete structure that must have served as a guard house, a cement pad that formed part of a weigh bridge and the unfilled pit are its only telltale remnants.
The rest of the pit has been refilled with broken rock and covered with soil, making it appear the same as before mining started. But now that the porous cavity under the soil coverage has filled with rainwater, the acid water is decanting down the hillside into the river passing along the valley floor below.
This long-term effect of mining on South Africa's precious water resources, as well as on the environment, is the reason why a growing lobby of environmentalists believes that there should be a complete reassessment of the country's natural resources and that mining should be kept away from areas where the damage inflicted would far outlast the immediate benefits.
Koos Pretorius, a local farmer and campaigner against indiscriminate mining, took me to the Witkrans site to show me these effects. His tests of the water seeping from the hill below the mine showed a pH of 3,9, which is deadly compared with the drinkable valley stream's pH of 6,6 before it meets up with the foul water. A good pH, which is the formula by which the acidity and alkalinity of water is measured, is about 7.
Pretorius says that, in addition, the water seeping from the mine has a total dissolved solids value of 1 208 compared with the stream's perfectly potable 42. Referring to the quantity of calcium, sodium, potassium and other minerals in the water, a total dissolved solids value of 260 is considered no longer suitable for irrigation, and at 450 it is not drinkable any more.
The acid mine drainage at Witkrans is similar to that from defunct mines in the Witbank area that has killed aquatic life in the Wilge River flowing through the Ezemvelo Reserve near Bronkhorstspruit and which has caused mass die-offs of fish and crocodiles at the Olifants River inlet to the Loskop Dam.
Pretorius is the chairman of the Escarpment Environment Protection Group, which consists mainly of farmers, business people and environmentalists who are worried about the immediate and even more disastrous longer-term impact on the environment of indiscriminate mining. It is taking the department of minerals and energy and the mines to court on the grounds that they are not adhering to the environmentally protective requirements of the law.
He is also involved with the Mpumalanga Lakes District Protection Group which is trying to keep the mines away from the Chrissiesmeer district with its more than 300 lakes and pans that together form an extensive ecosystem in which a large variety of plant and animal life, notably birds and frogs, thrive. It is an important bird area (IBA) and has been classified by the Mpumalanga Tourism and Parks Agency as "highly significant", with pockets of it being "irreplaceable". The classification categories specifically preclude mining.
The Witkrans mine was a small operation and, although its destructive legacy points at the difficulties small companies are having in controlling their effects on the environment, the damage it causes is comparatively restricted. With a sweep of the hand across the valley from it, Pretorius points at two massive collieries on the horizon. One day, their holes, too, will be refilled with broken rock, and when they start decanting, he says, they will yearly be sending several million cubic metres of acid mine drainage into the stream.
Meanwhile, applications have been made for at least two more mines in the immediate area, which is where the town of Carolina gets its water from. Further afield, between Carolina and Belfast, there are already about 15 more mines operating without water-use licences, says Pretorius, and applications have been submitted to open at least 30 more. "Ironically, it is the area that provides Eskom with the clean water it depends on for its operation."
The consequences reach further. The Vaal River starts near Carolina and passes big towns such as Standerton on the way to the Vaal Dam, from which most of Gauteng draws its water. Pretorius estimates that there are about 2 000 applications for prospecting and 296 applications for mining, mainly for coal, in Mpumalanga.
An influential voice against mining's long-term impact on our scarce water resources has been that of Professor Terence McCarthy of the school of geosciences at the University of the Witwatersrand. He saw last year's Ezemvelo and Loskop Dam disasters as merely a foretaste of what is to come.
And when he heard a few months ago about plans to open a new mine in the area northwest of Ermelo where the Vaal River originates, he warned that it could, within a decade, cause the water quality in the upper Vaal to deteriorate to the point where it would no longer be fit for human consumption.
He wrote to the consultants of Xstrata mining company that he considered it in the national interest that the proposed Spitzkop Greenfields Project should not go ahead.
"We know from past experience on the Olifants River in the Witbank area, where companies like Xstrata and AngloCoal are currently mining, that serious pollution of the river is unavoidable. In that case, the miners have managed to use the Witbank dams in conjunction with a controlled release policy to contain the pollution for the moment.
"This control is only temporary, however, and will be lost when the mines close," he wrote.
The worst about the dilemma is that there seems no way of stopping the damage. While environmentalists are fighting to keep mining away from sensitive areas, no government department, including the department of environmental affairs and tourism, seems capable of doing anything about it, despite all the talk about sustainable development and about the critical need to protect our freshwater resources.
When I recently talked to Valli Moosa, the former minister of environmental affairs and tourism, and now the president of the World Conservation Union (IUCN), he told me that, with the price of commodities such as coal being where it was, nothing was going to stop the expansion of mining.
All that could be done was to ensure that the legally required environmental impact assessments and post-mining rehabilitation requirements were properly adhered to.
He pointed out that the mining houses themselves took the initiative at the IUCN-sponsored World Parks Congress in Durban in 2003 to keep out of protected areas. That was a helpful step forward.
"We need to negotiate parameters and to ensure that all abide by the rules," he said.
Nikisi Lesufi, the environmental adviser to the Chamber of Mines, has taken a similar position, arguing that if areas were too sensitive for mining, they should be declared protected areas after due process in which all the facts got put on the table. The mines would then keep out, in line with the chamber's position that it would not mine in protected areas. But it was the responsibility of the relevant government departments to introduce such a process.
But the environmentalists want the safety net cast far wider. Their court challenge to the mines and the department of minerals and energy is on the basis that they are by-passing or simply ignoring the prescribed legal procedures.
But what they want is a complete spatial mapping of the country in which an area's importance as a freshwater source would count as a far more important consideration for keeping it safe from mining.
McCarthy says the issue goes far beyond protected areas. You have to look at the total impact and not only at how mining will affect the immediate area. All mines become acid-generating. The way we are going now creates a future vision of red rivers of acid and a lifeless landscape.
"It is late. The Olifants River we can write off. But the Vaal and the escarpment we can still do something about. We must look at things holistically. In some areas, mining will not have the impact on water as it will in others. And where mining is allowed in sensitive areas, every effort should be made to mitigate their acid production," he says.
Dr Anthony Turton, a water-resource expert at the Council for Scientific and Industrial Research (CSIR), says the way we treat our water resources needs to be a central part of a big vision for the country, which is just not there at the moment.
It is vital, for the sake of social stability, that the economy grows. But how to do this with limited water resources is the big question. Unfortunately, at the moment the discourse about it is not well informed. The country is already close to the limit of its assured water supply, and this makes it a business risk.
A major international company has already decided against building a factory here because it could not be assured of a guaranteed safe water supply in the longer term, he says.