Halfway can be a bit of a trick, particularly in late season. The spot where the trail crosses Vivian Creek, in the drainage a bit west of the junction with the spur trail down to Halfway Camp, is almost always dry unless it’s raining or there’s active snow melt. You just have to bushwhack upstream and be persistent. If I’ve gone far enough, I’ve always found water if I really made the effort. Sometimes it is just a trickle though.
Alternatively, and this is an act of desperation as I’ll explain in a minute, you can head ESE out of the camp area toward High Creek. High Creek is in a chasm, and you’d be crazy to go directly, but if you follow the little dotted line on my map, you can drop into high creek above the drop off. Warning, there is heavy brush at the head of the drainage that Halfway Camp is in. This is NOT an easy way to get water. As I say, try it if you’re desperate. Maybe you’ll find a way to avoid the brush, I couldn’t. It was Buckthorn. Not fun. But doable if you persist and are willing to tolerate a bit of pain.
Incidentally, for those who like a bit of adventure, you can go straight up High Creek from Halfway if you want an alternate route to High Creek Camp. Note that I said “alternative” not “easier.” It’s anything but easy with multiple falls and cataracts to climb. A slip on one of these could be, um, “unpleasant,” if you get my drift. All class three, so no equipment required, but proceed with caution.