Underground mine acid flows into a dam after rains. Picture: PUXLEY MAKGATHO
Underground mine acid flows into a dam after rains. Picture: PUXLEY MAKGATHO

ACID mine water has polluted a Kruger National Park river, killing a "massive" number of fish, after heavy rains contributed to the overflow of a tailings dam in the Phalaborwa region, South African National Parks (SANParks) said on Monday.

Acid mine water contains high levels of heavy metals and salts. It has affected vast areas of South Africa and is an urgent problem in the Witwatersrand, where it is projected that if the problem is not addressed in Africa and South Africa’s economic hub, it will lead to shortages of usable water from this year.

Department of Water Affairs compliance monitoring and enforcement director Nigel Adams said criminal charges had been laid against the Bosveld Phosphate mining operation, and the department was also taking administrative action against the miner.

The incident was detected by Kruger National Park staff after a tip-off by a local fisherman on December 30. The fisherman had seen the dead fish.

The spill polluted the Selati River, an important tributary of the Olifants River, a significant shared watercourse with Mozambique.

In 2013, a team of 30 scientists found that mining, industrial, agricultural and sewage pollution had caused a toxic soup that threatened the future of the Olifants River — estimated by the Council for Scientific and Industrial Research as South Africa’s third hardest-working river — and the health of the people and animals living in its catchment basin.

SANParks said in a statement that investigations into the environmental impact of the latest spillage continued and would be made public once concluded. There is also continuous monitoring of the rivers affected to assess their condition.

Mr Adams said the pollution had been contained and the river’s acidity level was tested every three hours.

Water had been released from the Blyde Dam to dilute the pollution, he said.

"The situation is improving," he added.

SANParks said it had taken "immediate precautions" to ensure safe water supply to tourist camps in the park.

Camps dependent on water from the Olifants River were switched to back-up borehole water, with associated water-use restrictions to ensure that demand could be met.