An Argentine court has ordered a halt to gold leaching processes at the Valdero gold mine operated by Barrick Gold, initially for five days but this was then extended to allow for a full investigation. The Veladero mine is one of the largest gold mines in Argentina, producing 722,00 ounces of gold in 2014. The mine is located in the Argentine province of San Juan near to the Chilean border. 
According to the court, there was a leak of 15,000 liters of cyanide from the mine, caused by a defective valve. The leak was found on Sunday 13 September. There is concern that the cyanide leaked into the Blanco river, this could cause severe environmental damage if the river is heavily contaminated.
After the investigation began the company admitted that it was not a discharge of 15,000 liters of cyanide, but more than one million liters. Independent specialists have been called in to investigate and take water, soil and plant samples.
The provincial authority has recommended that until there is certainty over the severity of the spill, the people in the three adjacent cities of the Blanco River should avoid any water consumption. Cyanide is also very harmful to the environment, even in small quantities, especially to fish.
Update: A UN investigation in to the leak has shown that the impact of the cyanide was minimal: “Samples taken from surface water five days after the spill “showed no deviation from measurements taken in June 2015,” Reuters quotes a report by UN investigators. 
 Mining.com: Barrick’s Veladero gold mine in Argentina halted over cyanide leak, . 2015 accessed on 09.23.2015
 Mining.com: Argentina extends Barrick’s Veladero gold mine halt, 9/23/2015, accessed on 09.28.2015
 Mining.com: Barrick’s Veladero gold mine in Argentina halted over cyanide leak, /, 17:09. 2015 accessed on 09.23.2015
 rt.com:Canadian mining company admits to 1mn-liter cyanide spill in Argentina, 09.25.2015, accessed on 28.09.2015
 earthworksaction.com: CYANIDE IN MINING: SOME OBSERVATIONS ON THE CHEMISTRY, TOXICITY AND ANALYSIS OF MINING RELATED WATERS, 18.01.2011, accessed at 24.09 .2015
 Mining.com (2015): water supplies uncontaminated