South of Ketchum and Gannett, the Silver Creek is a challenging spring creek for trout fly fishing. The creek is plentiful with rainbow trout, but they are tough to land since they hang out in the grasses. Wading can even be challenging since the bottom is very muddy; its best to try a belly boat. Moreover, since much of the creek runs through private land, it may be better to try canoeing this creek. Even with all the hassles, the rainbows and browns are large and fat, and are known to be up to 24 inches. It is known for an excellent steelhead season, too, from mid-March through April.
The Silver Creek is located about 30 miles south of Ketchum. A good place to start is the Silver Creek Preserve owned by the Nature Conservancy. There is great Silver Creek access with exceptional fly fishing (make sure you are aware of the current regulations at this site). In addition, there are some access points off of SR20, SR93 and other county roads.
Overall, Silver Creek is the 9th most popular fly fishing river of all 17 fly fishing spots in Idaho.