Just for clarity for others, the reason the water needs to be cool is so that after being used for cooling it doesn't come out too hot and kill wildlife. French plants have applied to temporarily lift these restrictions[1] (which also is not great).
If this becomes a problem longer-term, it might be possible to build larger cooling reservoirs for the water prior to being released back into the river.
1: https://www.reuters.com/world/europe/frances-asn-nuclear-reg...
The water doesn't really need to be cool, it can also be used in cooling towers, which means you don't have to put it back into the stream, and therefore you don't care about water temperature. The issue with river water is that we currently don't have enough to divert it for all our needs, be it for a nuclear plant, for irrigation or for drinking.
This winter and spring have been exceptionally dry in France, with slightly more than half the rain we usually get.
We have currently seen major droughts in Europe and it severely affects the ongoing energy crisis. A lot of power plants, nuclear and others, are in direct danger of not being able to be cooled anymore because you need RIVERS for that. And they need to be cool.
Germany is currently experiencing issues with low water levels in some of its major waterways, such as the Rhine. When they dry up to low levels periodically, and they evidently do nowadays, then you have to shut down the plants accordingly.
In France, rivers are too warm to cool plants [1]. There needs to be water AND it needs to be cool. There is no nuclear power without water cooling.
[1] https://www.reuters.com/business/energy/warming-rivers-threa...