Earlier quoted context omitted.
>we need to take into account the carbon cost of storage. Since this doesn't exist, it is an unknown. NY appears to have plenty of hydro from that graph. It's not all that hard to close the sluice gates and open them later. Grid scale batteries are also cost competitive (as of the last 12 months or so), though they wouldn't be as cheap as hydro for dispatchable energy.
Hydro has issues with reliability as well. You could have a long drought.
Is NY hydro largely generated at Niagara Falls?