What if you funneled Niagara Falls through a straw?

A truly ridiculous scenario was submitted to the What If? series. What would happen if you tried to send all the water going over Niagara Falls through a straw? That's 50,000 to 100,000 cubic feet of water per second! They gamely explain why you can't do this, with some of the finer points of fluid dynamics, and how this attempt would trigger some bizarre effects. 

Most of that went over my head, but I wondered how they knew that the flow was 50,000 to 100,000 cubic feet per second. It turns out that's the mandated minimum amount of water regulated by treaty. A lot more Niagara River water is diverted for power generation. The preservation of Niagara Falls is overseen by at least five different organizations- or else the falls could be dry a lot of the time. You can learn a lot from a stupid question.