You know, I remember reading all that stuff on the back of my wilderness permit, and I had some trouble figuring out what was simply recommended and what was required by Yosemite regulations (the stuff I might get fined for or told to leave). I remember seeing some campsites that were extremely well established, but didn't meet the 100 ft from trails and water sources.
I was tired and I needed a place to rest, so I just found a nice site, although it was a little over 30 ft from a stream and maybe 40 ft from the trail, but could find no other options short of asking to stay in someone else's spot. Turns out that I was OK according to the regulations in place (I think the rules on backcountry camping probably haven't changed ). I did see one free-standing tent that was unstaked and where the corner was actually dipping into a small stream.
Quote
Camping is prohibited in the following areas:
• Within 100 feet of a trail, flowing stream, river or any body of water, unless designated,
and as follows: Camping is permitted within 100 feet of a stream, trail or body of water
provided that a well established campsite exists and terrain permits no other options. In
no case will camping be permitted within 25 feet of a stream, trail or body of water.
In any case, I'm going to be going over this. It might be useful to know just in case I come across a situation where I'm not sure what I can or can't do.