Thermoelectric plants often change their local ecosystem by raising the temperature of natural water bodies used for cooling.

However, it doesn't have to. And in particular, as water becomes more constrained by growing population and climate change, using water the same way that it has in the past is becoming untenable.

Recent regulations are starting to end "once through" use of water this way, which is leading to the shut down of older plants that are close to the end of their lifespan anyway.

And then there are plants like this nuclear plant in Arizona which cools using treated sewage, which has almost zero impact:

https://en.m.wikipedia.org/wiki/Palo_Verde_Nuclear_Generatin...