[tomatocracy]

Run-of-the-river hydro in all but a handful of sites tends to be quite dependent on rainfall levels. This means production levels can vary quite meaningfully both seasonally and more importantly year-to-year.

It's definitely reliable in the sense that hydro stations can basically last forever if properly maintained (there are plenty of hydro stations operating today which are more than 100 years old) but it's not quite a silver bullet.