I've run across one at Anvil Camp on the way to Sheppard's Pass to Tyndall/Williamson, it was between 10,100 and 10,200, that's the highest so far that I've seen one.
Anvil camp is major camping area that brings about all the vermin, thus a great feeding area for any type of snake so I was surprised but not that surprised.
They don't bother me but I wouldn't want to one to snuggle with me when I was trying to sleep in my bag out there, that might have me a little nervous.
The largest in the wild I've seen was almost as fat as a baseball about 7 feet long just off the road in Yosemite, that one scared me because it was close enough to strike my daughter who was with me at the time, needless to say he went away unhappy as I used to pitch baseball and have a nasty fastball, rocks make great baseballs

we were at one of the view points off Wawona Road by Bridal Vale Falls that leads to the valley at about 4,200 feet if I remember correctly back in the 80's.