In addition to fishing some high altitude lakes, I was also able to hike and fish some high country streams in Colorado this summer. I made two separate day trips, hitting two different fork of the St. Vrain river. Both trips were easy hikes, with the creeks running right alongside the trails for the most part, but requiring some walking between fishable sections.
These pocket water streams are fun to fish because you are usually only fishing one small section of water at a time. A drift is usually only 1 to 4 feet long, and back casts are impossible. All you need is a short roll cast at most, but usually just a “flip” over of the fly. I fish a 7-foot fiberglass rod and keep about 4 feet of fly line out of the guide. I flip the fly up to the top of the pocket and high-stick the rod, keeping as much leader off the water as possible without inducing drag, letting the fly drift down, and then flip it back up to the start. Usually three or four casts is all it takes to see if any fish rise to the fly or not, then you can move on to the next pocket.
I like to use a big foam dry fly, such as a Chubby Chernobyl, for this type of fishing because you can throw it into a rapid at the top of a run and it will just pop back up and float through the run. Sometimes mending is required and can make all the difference, in one spot there was about a pillow-sized section of non-moving water in between a few boulders, and using mends as needed I could keep the fly sitting in that one spot until a brook trout eventually came up and smashed it.
Below is a video and some photos with captions showing the type of water I am describing, as well as some of the catches, enjoy!