It's complex there are few environmental effects from blocking the falls as they are already one way and tend to kill fish that make the trip. However, there is a treaty that set's minimum flow levels and more water is diverted at night to a holding area which is then used for hydro in the day.
Anyway, the area already has plenty of pumped storage it's only by importing a lot of power that you would need to expand. But, at that point you can scale really far with few environmental costs.
It's complex there are few environmental effects from blocking the falls as they are already one way and tend to kill fish that make the trip. However, there is a treaty that set's minimum flow levels and more water is diverted at night to a holding area which is then used for hydro in the day.
https://en.wikipedia.org/wiki/Niagara_Falls_hydroelectric_ge...
Anyway, the area already has plenty of pumped storage it's only by importing a lot of power that you would need to expand. But, at that point you can scale really far with few environmental costs.