As the falls erodes back from Lake Ontario, toward Lake Erie, it erodes on average, at about 1 foot per year. This eroded rock (called "talus")
piles up at the foot of the falls...now reaching nearly half the height of the falls.
In 1969, and after much preparation, engineers and construction workers, turned off the American falls. Well, they didn't actually turn it off, so much as the re-routed it over the Canadian side.
http://wakeupniagara.weebly.com/1969-falls-shut-off.html#.ZKq5SnbMLrc The falls had only "dried up" once before in recorded history, when in 1848, the ice breakup of Lake Erie, clogged the Niagara river for some hours.
In 1969, they re-routed it to decide what to do about the talus.. and they decided to do nothing. Much long forgotten debris was found, to include a couple human bodies..one male, one female..and other items from who knows when..
They are contemplating another shut down, so they can repair an old stone bridge that allows tourists to get all wet from walking in the mist.
