Interesting concept, I haven't seen that before. Whether it would work here (I live in the Sierras) though, my guess would be probably not for two reasons. One

Interesting concept, I haven't seen that before. Whether it would work here (I live in the Sierras) though, my guess would be probably not for two reasons. One is temperature, as you mention. Our higher mountain lakes do freeze over, but I'd expect you need colder temperatures than what we see on average for something like that. Running water typically doesn't freeze here, even during the coldest part of the Winter. The second reason is scale. Only a portion of the water that falls on the Sierras lands up high, and much of that is captured in snowpack , which is a pretty key piece of the water storage puzzle already.