There has been a lot of publicity around wind and solar power, but not much on water power. But water power has been around for a long time. Water power runs 24 hours a day, every day. Whereas wind and solar are “hope” power. You “hope” the sun shines and you “hope” the wind blows.
Therefore you have to have another source of power for when the sun doesn’t shine, which is half the day, and another source of power for when the wind doesn’t blow. Therefore you have to invest in another power system to supply power when wind and solar don’t. With hydro you don’t need that, which is partly why it is most cost effective.