Monday, 15th January 2007 by Alex Turnbull
This is the infamous Berkeley Pit in Butte, Montana. This enormous open-pit copper mine was opened in 1955, and when it was closed in 1982, groundwater began to leak into the basin – disastrously passing through the metal deposits in the soil. The water became laden with a deadly mix of heavy metals and poisonous chemicals such as cadmium, zinc, arsenic and sulphuric acid.
There’s an estimated 30 billion gallons of water in Berkeley Pit which is (despite major cleanup efforts) still incredibly toxic. The water here was reputedly responsible for killing 342 snowgeese who landed here in 1995, and apparently has a pH level of about 2.5, which ranks it more acidic than tea, coffee, acid rain, beer, orange juice and vinegar. That’s as acidic as cola and only slightly less acidic than gastric acid… (Update: It turns out “only slightly” is misleading. See this comment for more information.)
You can read more about Berkeley Pit at WIkipedia.