Rainey Creek is a large tributary stream that is thought to be an important haven for pure Yellowstone cutthroat trout. The resident cutthroat in Rainey Creek may benefit from degraded stream conditions near the confluence with the South Fork of the Snake River which may prevent immigration of rainbow trout and hybrid trout.

We did not find many trout in the lower reach, however the trout that remain in this degraded reach appear to be pure Yellowstone cutthroat trout. Although there is some grazing in the middle section of Rainey Creek, we found healthy populations of cutthroat trout. The upper reaches of Rainey Creek contain complex habitat with large woody debris and beaver/muskrat impoundments which provide important rearing habitat for young trout.