One of my favorite places to fish is the Copper Basin area. It is located just outside of the resort town Sun Valley. The high mountains surrounding this area provide the streams with cool, snowmelt water. This area has a short season due to runoff and its high elevation. It is best fished from mid July- mid September (depending on snowpack and weather.)
I made the drive in my Camry, but I don’t recommend it. If the road is muddy or if it starts to rain or snow you might get in trouble with a two wheel drive vehicle. An all wheel drive or four wheel drive vehicle is a better choice if you have the option.
Call one of the fly shops in Ketchum and ask if runoff is subsiding. The river was clear, but still a little fast when I went in early July.
I never had cell phone service while up there, and it is fairly remote. Make sure to pack a small first aid kit, a blanket, and PLENTY of drinking water. If your car breaks down you need to be prepared.
Please note that there is also a lot of wildlife in the area. Moose are abundant. I love seeing the various animals, but I carry bear spray in case something goes wrong. As always give the animals their space and you shouldn’t have any problems.
The upper Big Lost and its tributaries are freestone rivers/streams. Attractor dry flies; terrestrials; and standard nymphs such as pheasant tails, copper johns, zebra midges and hares ears are good patterns to have.
For those who love to dry fly fish this is a great place to be. Devote more time to reading the river than worrying about you fly pattern. I experimented with about half a dozen dry flies (mainly attractor patterns), and I was able to get fish to rise to them all.
I had the most luck fishing soft edges near overhanging brush. However, I was fishing when the river was still pretty high. Fish might move to deeper pools as the river flows drop later in the season. As always it is up to you to experiment and figure it out.