Our hydro plant is @ a dam, so at lower demands the water bypasses the turbines and gets directly into the river, and at high demands the bypass is closed. There is always a tiny flow, intended for fish.
if apocalypse broke out, i'd fort myself a base in there.
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__________________
If you don't make any mistakes in your life,
life itself will be a f*ckup.
With Volvo to Valhalla and back!