Water at High Creek Camp is nothing to worry about. It’s very reliable.
Take a look at this map: https://caltopo.com/m/5EJT
The most convenient water source is in a side canyon just east of the camp area. It’s marked “Spring/Side Creek”. The camp area is on the main branch of High Creek.
If for some reason the spring were not running, just go down the main branch a little ways below camp. You’ll find water just above High Creek Falls.