If I am reading the article correctly. It looks like the river water is too warm due to drought conditions. This would be possible as the high heat and lowered runoff decrease the water level allowing the water to warm more quickly. This situation also lowers the available cool bottom waters.
That sounds reasonable - hopefully the media will have a rational reading of the situation. Droughts happen.
They don’t say its just an environmental issue though. It would be nice if they clarified.