Snake River -Lake Walcott to Confluence of South Fork and Henrys Fork
The Snake River from Massacre Rocks upstream to the confluence of the North (Henrys) and South forks encompasses a variety of habitat types. This section extends approximately 125 miles, of which approximately 20 miles is flooded by American Falls Reservoir.

The six miles of river from Eagle Rock upstream to American Falls Dam is considered a Class 1 trout stream.

American Falls Reservoir covers 56,000 surface acres and has a usable storage of 1.7 million acre-feet. The reservoir is stocked annually with catchable rainbow trout in the early spring and growth is significant.

The Snake River from the backwaters of American Falls Reservoir upstream to Tilden Bridge, a distance of approximately 20 miles, is a Class 1 stream. The two best-known springs in this area are Clear Creek and Spring Creek, both Class 1 waters for 7 miles and 11 miles, respectively. These springs contain rainbow trout, brown trout, cutthroat trout, and mountain whitefish.

The Snake River from Tilden Bridge upstream to the Gem State Power Plant spans 37 river miles and is characterized by low unstable banks of small river rock. Hatchery rainbow trout comprised the majority of the population; however, large wild rainbow, brown, and cutthroat trout are found in this reach also. Reservoirs and ponds along the Snake River in this area include Springfield Reservoir, McTucker Ponds, and Rose Pond. Springfield Reservoir covers 66 surface acres and is annually stocked with catchable-size hatchery rainbow trout. McTucker Ponds are eight small gravel pits covering 25 surface acres, located near the upper end of American Falls Reservoir. Annually planted with catchable-size trout, they also contain largemouth bass, bluegill, and channel catfish. Rose Pond is located north of Blackfoot and contains rainbow trout, bluegill, and largemouth bass.

The Snake River from the Gem State project to the outflow of the upper Idaho Falls Power Plant is essentially a put-and-take hatchery rainbow trout fishery. The remainder of the upper Snake River from the Idaho Falls Upper Power Plant to the confluence of the Henrys Fork and South Fork (39 miles) produces occasional large rainbow and cutthroat trout. Brown trout are also caught in this reach. No hatchery stocking occurs in this reach of river. Reservoirs and ponds along the Snake River in this area that support fisheries include Roberts Gravel Pond and Market Lake. Roberts Gravel Pond covers 35 surface acres and contains yellow perch, rainbow trout, channel catfish, bluegill, pumpkinseed, and bullhead. Market Lake WMA water channels contain yellow perch, bullhead, and Utah chubs.