I spent several days this week fishing the C&R portion of the South Platte in 11 Mile Canyon. Despite the low flows, heavy crowds and tons of rock snot snagging flies, the fishing is actually outstanding right now.
Each day yielded dozens of good fish, including two of what I'd call a South Platte Slam, if I could say definitively that there are no brookies in there: a rainbow, brown, cutthroat and cutbow all in the same day.
If you're going, bring some green JuJu Bees, Juju Baetis and Flashback RS2's and some size 22-24 Adams or BWO for the rare hatch.
The best tactic is to drop one of the above flies off of an attractor like a nuclear egg, san juan worm or rubber legged stone fly and put enough weight to keep it bouncing off the bottom. I fished two nymphs under weight and never did as well as I did with an attractor on top, which was weird since I can count on one hand the number of fish that actually hit the attractor. Stick to 6x fluorocarbon tippet for underwater stuff and 7x for the top. Despite the lack of hatches due to the blue bird conditions, it was possible to find decent fish sipping sporadically in the slow water on the side and at the back end of big pools, it just takes a good cast and drift to get them to take.
Also, for all the fisherman I talked to that were getting skunked: don't just fish the big, obvious pools. Anywhere there is semi-swift water and a shallow tub, you'll find a decent fish sitting at the back end of it, eating everything that comes within reach. I avoided the crowd and caught a lot of fish by casting to the spots a lot of people walk by on the way to the next "hole." Finally, with flows in 50s and 60 CFS and not a cloud in the sky, you really need to sneak up on any trout you want to catch....I think I nearly wore holes in my waders this week!
Here's a pig of a cutthroat I caught in a short, deep run between two "holes"