That water is HIGHLY unlikely to be 9 degrees Fahrenheit as they don't use the Fahrenheit scale in that area, and while it is indeed possible for water to remain in liquid state at 9-degrees Fahrenheit if a number of (rare) conditions are right for a supercooled liquid state, there would at least have to be signs of ice along the shores and none are visible. The most like scenario is that the river is 9 degrees Celsius which is in the ballpark of fifty degrees F. That's still cold, but a plunge into 9-degree Fahrenheit supercooled water would likely send anything warm blooded into an immediate cold shock death spiral.