Niagara Falls

100,000 cubic feet of water falls over Niagara every second--this is about half of the volume that would naturally fall.  A treaty was signed in the 1950's between the US and Canada designating that at least that much volume must flow during daylight hours during peak tourist season.  On the off-season and at night, flow is reduced so that more water can be used to create electricity.  (DSL/Cable users: click to enlarge)