Soda Butte Creek
Like many of the other streams in this area of YNP, terrestrials are typically the fly of choice in the warmer summer months. The primary mayfly is the PMD and there are also some green drakes.
The average size of the fish is 12" although there are certainly bigger fish to be found. The biggest trout I have taken there was a 17"+ cutbow taken in a #16 black ant.
Access is very good for most of the stream's course as the highway (212) that runs from Cooke City to Tower Junction follows the creek very closely throughout much of its length.
This northeast corner of YNP is a bit out of the way for most fly fishing activity and many fly fishers will not make the trip from the more popular waters to the west of the park. Once you get out to this area, you also have the Lamar River and just to the north is Slough Creek.
More information:
Soda Butte Creek - by Montana Angler
Soda Butte Creek | Fishing - by bigskyfishing.com
Fly Fishing Soda Butte Creek - by Fly Fishing Yellowstone National Park