If you time it right, the fly fishing on a freestone river can be magical in the hours before the runoff explodes. A few days ago, I made a journey up the Poudre River with Dave and Jason in hopes of finding fishable water. A quick check of the stream flow report indicated that the river was at about 500 CFS at the mouth. It was too windy to float tube on a favorite lake, so we decided to travel up the canyon to try our luck.
We found a nice stretch of river where the water was still somewhat clear, and mostly wadeable. Using a variety of flies (mostly zebra midges, and hares ear nymphs), we all landed nice trout.
Trout can sense when the river is about to hit runoff, and they can activily feed. Although you can still do well fishing the edges of a river during runoff, I often turn my attention to the various lakes in my area during late May and early June.
Enjoy your Spring fishing, and let me know how it goes!