The burden on proof should be on "dumping hot water to a river doesn't damage its ecosystem" rather than the opposite...
> capture heat directly at the source and transport it to outdoor dry coolers, essentially large radiator coils positioned outside the building.
The heat goes into the air
Can confirm : I'm reading this from France, we're in the 8th day of the meanest heatwave the country has known since records exist, and it's expected to last two more.
Dumping hot water into rivers harms ecosystems regardless of whether anyone happens to do it right now, and asking for a citation for that is such a WTF in and of itself we really shouldn't gloss over it.
And nothing at all is too stupid of a question to want an answer to. That way leads to people screaming at each other over social media instead of engaging with facts.