Not if the lake is going to be there in either case.
However, storing months of power is silly, you are much better off with extra ~6c/kWh wind/solar that you use 1/2 the year than trying to store ~6kWh energy for six months.
Renewable are the new base load power becase they are Cheap and you don’t gain from not using that energy. They still need peaking power or storage to follow the demand curve.
PS: Say it three times fast ‘base load power is a downside.’
https://en.wikipedia.org/wiki/Robert_Moses_Niagara_Power_Pla...
Evaporation is a real concern if you start talking about storing months of energy.