Oh boy, fermi estimation time! Big caveat: all of the below assumes ideal mixing, which is not a given at this scale at all. So I'm not rubbishing the residents. (Nor disputing the idiocy of burning 45 MW to "mine" numbers for that matter.)<p>From wiki, the lake has a volume of 15 km3, or 15 trillion litres. The daily discharge of 135 million gallons is ~ 600 million litres. So, per day, it's cycling about 40 parts per million. Alternatively, you'll cycle the volume of the lake once every 67 years at that rate.<p>That same discharge is ~ 7000 litres per second, which will require 30 MW to heat by one degree Celsius. It's listed at at most 45 MW, so one and a half degrees rise, unless any of the water is evaporated, which it quite possibly is (after all, more is licensed to go in the plant than come out. I wonder if they have some scheme where a small volume of water is heated to a point where evaporation matters, then it is mixed back in?).<p>Once again, the locals <i>may</i> be noticing, but only if very significant stratification is occurring. Water is <i>good</i> at dissipating heat.