My favorite spring fishing rivers include the Kinnickinnic River in River Falls, Wisconsin. The trout in this river are largely naturally reproducing, and have great color. The fly rod and small elk hair caddis flies will take fish, such as the one photographed above.
Another favorite is the Willow River in Hudson Wisconsin, I have taken large Brown trout, large Rainbow Trout, and brook trout up to 12" long all in one fishing trip before on this river. This great state is an angler's paradise, it really is.