(And 'purest'.. as seems not to accord with a generally poor budget for environmental issues.)
Then there's Ours--Repos determined next to kill as many enviro protections as they can, fucking Vandals.
Lake Baikal is the most voluminous freshwater lake in the world, containing roughly 20% of the world's unfrozen surface fresh water,[4][5] and at 1,642 m (5,387 ft),[1] the deepest.[6] It is also among the clearest[7] of all lakes, and thought to be the world's oldest lake[8] at 25 million years.[9] It is the 7th largest lake in the world by surface area.
http://en.wikipedia.org/wiki/Lake_Baikal