Near Aspen, the Roaring Fork of the Colorado River starts at Independence Pass and flow down through Aspen to Glenwood Springs. This 75 mile river has many fishing opportunties and most of it is wadable. While not wilderness, it is highly accessible via the roads that run parallel to it. You can expect to find plenty of rainbow trout, brown trout, cutthroat trout and brook trout.
The best section for fly fishing on the Roaring Fork River is the 28 mile Gold Medal Trout Water starting from the confluence with the Frying Pan River in Basalt. While late summer can be nice for wading, the section is mainly floated. Near Carbondale, the confluence with the Crystal River turns the Roaring Fork River into a large river best suited for floating only.
Note: The printable fly fishing river map is provided courtesy of HANDYMICROFIBERCLOTH.COM.
Overall, Roaring Fork River is the 20th most popular fly fishing river of all 47 fly fishing spots in Colorado.