The Sawtooth area is an amazing outdoor recreation area. Not only are the waters full of fish (for the most part) and the scenery breathtaking, there are also an abundance of natural hot springs in the area if you know where to look.
I grew up only a 100 mile drive from the area and had the fine pleasure of making the Sawtooths my "growing up" hiking home. If anyone is looking to visit there, I highly suggest completing the 100 mile or so round trip hike from Stanley to Atlanta and back. It is very much worth the effort. One of the coolest waterfalls I've ever seen is along the north fork trail of the Boise river (the river looks like it falls through a hole in a rock, and there is a little hot springs at the base if you are brave enough to look!). Also, as you approach Atlanta (make sure you visit the town, it's really fun!) you'll encounter some excellent hot springs. Make sure you visit Chatanooga. It's at the base of a cliff, and there is a little hot water waterfall that flows into it off of the cliff face. It's also located about 20ish feet away from the Boise river. Beware of skinny dippers, and don't be surprised if you catch a local bathing there.
I am seriously envious of your picture, it is gorgeous. There are only a few places that I've visited that compare to the area in my opinion, and all of those are in Alaska.
Sorry to ramble, seeing the picture got me really excited, and I miss that area terribly.