Not only that, they use the gravitational potential of the falls to store massive amounts of energy when there's a surplus. Way cheaper to hold or even pump the water back up to the reservoir at the top than build lithium batteries. So yeah, as a local, can confirm they turn Niagara Falls (partially) off at night. Thanks to the Falls and several nuclear plants on Lake Ontario, Upstate NY and Southern Ontario have some of the lowest carbon electricity in the countries. Quebec is even better with basically all of their power coming from hydro.

See also https://en.wikipedia.org/wiki/International_Control_Dam

What do you think is happening to the water not being utilized in the production of power? I assumed it's still being run downstream, just not through the power producing turbines.

I'd expect there's not a big effect on the ultimate amount of water being released downstream either way.

I looked into this more, and there is quite a bit of seasonal variability to contend with as well.

There is no way it’s max is 7MW. They likely meant 7GW.

7MW is the amount of power you can get from a couple of diesel gensets, waaaay smaller than even a small power plant

[https://www.cat.com/en_US/products/new/power-systems/electri...]

Vogtle is also the most expensive electricity in the world, the only electricity costing more than $10,000 per kW.