I agree with Mike. It's a spring. It will have water year round.
I've seen the pipe many years ago. I think someone removed it for some dumb reason.
Couldn't find it for the life of me that last time I spent some time looking for it.
(the pipe that is). Regardless there will be water there.
I highly doubt that you will find the "spur" trail though. It certainly didn't jump out
at me last year when I hiked up HD although I wasn't really looking for it.
You can camp anywhere you like pretty much after you hike the HD/JMT trail
junction.
There is ALWAYS water at the Clouds/JMT trail junction. If you are super concerned
about getting water from the spring it's a short hike to that water from the HD/JMT junction.
Have fun