...Acid drainage from thousands of abandoned mines in Johannesburg has poisoned major lakes in the South African city. Experts say the toxic waters are rising at an alarming rate and are threatening to infiltrate the city's fresh water supply. Officials are now seeking solutions for the problem, which some have accused the government of neglecting for years despite warnings. Al Jazeera's Jonah Hull reports from Johannesburg, where the once popular Robinson Lake has lost many frequent visitors due to the acid drainage.