It all depends on when you get there. Spring is cold, but summer and fall the river is just right.
Warm in the summer
Spots along river do have some hot springs running into the river
Like everyone said there are parts where the natural hot spring leak into the river and those spots are warm but for the most part it’s a cool water river.
We went there over father's day weekend in 2017 when the water level was quite high, and the water temperature was warm enough to swim in. Granted, we were only in the water long enough to get in and out of tubes.
As mentioned in parts
In parts
yes
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