|Snake River Canyon, north of Twin Falls.|
With the exception of spawning areas, trout habitat in the main Snake River is good throughout most of the free-flowing reaches between C.J. Strike Reservoir and Lake Walcott. It is especially good in the section between Milner Dam and King Hill, where large amounts of spring flow are discharged into the Snake River from the Snake River Plain aquifer. An approximate average discharge of 5,900 cfs (4.3 million acre-feet/year) flows from these springs along the north bank of the Snake River. These springs include 11 of the 65 springs in the United States which have an average discharge exceeding 100 cfs.
Trout, such as rainbow, brown, cutthroat, and rainbow x cutthroat hybrids, are found in portions of the Snake River, below Minidoka Dam and Upper Salmon Falls Dam. The cutthroat trout and rainbow x cutthroat hybrids are found mainly in the area between Milner Dam and Twin Falls Dam, an area seriously impacted by low flows during the irrigation season. Many of these hybrid trout attain large sizes, some reaching weights of over 6 pounds. Vinyard Creek, an aquifer spring entering the Snake River on the north side just above Twin Falls, is the major spawning area for cutthroat trout and the rainbow x cutthroat hybrid trout.
Many of the minor tributary streams entering the Snake River also contain good trout habitat and support good populations of wild trout, primarily rainbow. Some of the streams, especially the springs, are utilized for spawning by trout from the Snake River.
The main Snake River contains seven reservoirs which are suitable in varying degrees for trout; Bliss, Lower and Upper Salmon Falls, Shoshone Falls, Twin Falls, Milner, and Lake Walcott. The trout fishery in Lower Salmon Falls Reservoir is the best of the six reservoirs, with the fishery being supported by releases of hatchery rainbow trout.
White sturgeon are found in varying numbers throughout the Snake River from Shoshone Falls downstream. The best sturgeon population, however, occurs in the free-flowing river section between Bliss Dam and C.J. Strike Reservoir, where they are successfully reproducing.Major warmwater species present in the Snake River and surrounding waters are largemouth and smallmouth bass, bluegill, brown bullhead, channel catfish, and yellow perch. Channel catfish plantings were made almost annually in the main Snake River in this area between 1965 and 1972. Periodic plantings have been made in the Snake River and nearby waters since 1972, and self-sustaining populations have become established between Bliss Dam and C.J. Strike Reservoir. Emerald Lake near Burley has been stocked with channel catfish fry for a number of years.