"They can't rely 100% precisely because hydro is unreliable." True in an absolute sense but in comparison to solar and wind hydro is extremely reliable, and can be used to power the grid when all other energy sources fail [1,2]

As far as Mosul I'm unsure, maybe someone else more informed can chime in on the actual state of affairs there since wikipedia/google turned up multiple contradicting results for me.

[1] https://en.wikipedia.org/wiki/Hydroelectricity#Advantages

[2] http://www.hydro.org/why-hydro/reliable/

Mosul is hardly an example of a well engineered dam though built in 1984 and falling to pieces. The Hoover Dam was built in 1933 and is not in need of pulling down.

If maintenance were interrupted (social upheaval) then Hoover too would fail. It take maintenance to keep it running - in particular mussels would foul and stop the turbines in a few seasons.

> If maintenance were interrupted (social upheaval) then Hoover too would fail.

Probably not in your lifetime let alone in a generation. Mosul's an issue because the substrate is not suitable for dam building (it's soluble gypsum, so it just keeps eroding because dam foundations kind-of tend to be around water) so the dam has to be continuously grouted to prevent it from failing.

Add Mosul holds 2.5 million people on a floodplain. When the dam fails catastrophically, it will be a bloodbath. It'll happen in the next few years.

They're not really comparable are they? It's not whether the turbines in the dam will continue to generate electricity, but whether or not the dam itself is structurally sound. My limited understanding is that the Mosul dam is not, while Hoover will outlast us.

The risk in the case of Mosul is failure of the dam face itself. Not merely the generating equipment.

Hoover faces no threats of similar magnitude.

It depends on where the dams are. I live in the North Eastern USA. Most of this part of the country (and eastern Canada) are powered by hydro. Niagara Falls doesn't turn off. Neither do dams, really. Even in the winter (-30F) and during summer droughts, they have water passing over the turbines. None of the dams in my area have needed maintenance in the time I've been alive (about 30 years).

It's cleaner and more reliable than any other kind of energy production on the planet including coal and oil. Nothing is 100% reliable, but hydro is the closest we're likely to get.

Everything requires maintenance. Solar panels have to be cleaned or replaced if they get scratched. You have to clean the bird carcasses out of the windmills. Nuclear requires constant supervision. There's no maintenance-free option.

Coal also requires humans to transport lots of fuel to it, and lots of big machinery to get that fuel.

It depends. Where I'm from we run on 97% hydro power and we never run out.