If Jason abandoned the car closer to 11:30 (having arrived directly from the last known intersection), an hour would've elapsed before the vff came upon it.
We don't know why he removed all of his clothing, but if he did make his way to the water and entered it, IMO two things would've occurred -- one, he'd have been slapped lucid and he would've sped up hypothermia exponentially. I think the former would yank him awake and yank him out of the water at which point he may well have tried to get back to his vehicle, without a good directional sense to do it.
These abandoned wells, would they produce steam? Warmer air from below meeting near freezing air from above?
If Jason was literally freezing to death, would a steaming hole look like a safe haven, like an oasis in the desert, a warm place on a frigid night?
It would've been pitch black, he'd have no way to know the ground would give out. If all he saw was steam...
If Jason went into the water, even if he escaped the water, he was in serious trouble fast.
JMO