The Snake River from its source to Jackson Lake, from one mile downstream of Jackson Lake Dam to one mile downstream of the Teton Park Road Bridge at Moose, Wyoming, and from the mouth of the Hoback River to the point one mile upstream from the Highway 89 Bridge at Alpine Junction. Shoshone Falls has presented a total barrier to the upstream movement of fish for 30,000 to 60,000 years. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox. The Snake River (left background) at Hagerman Fossil Beds National Monument, southern Idaho, U.S. Get exclusive access to content from our 1768 First Edition with your subscription. The Minidoka Irrigation Project of the U.S. Bureau of Reclamation, created with the passage of the Reclamation Act of 1902, involved the diversion of Snake River water into the Snake River Plain upstream of Shoshone Falls in order to irrigate approximately 1,100,000 acres (4,500 km2) in the Snake River Plain and store 4,100,000 acre feet (5.1 km3) of water in Snake River reservoirs. Several years later, a ferry was established at the site, replacing the old system where pioneers had to ford the wide, powerful and deep Snake. On the north the Snake River watershed is bounded by the Red Rock River, a tributary of the Beaverhead River, which flows into the Jefferson River and into the Missouri River, part of the Gulf of Mexico drainage basin. However, the lodgepole pine has increased in number, taking over historic stands of other conifers. In the 1890s, a huge copper deposit was discovered at Eureka Bar in Hells Canyon. The first studies for irrigation in the Snake River Plain were conducted by the United States Geological Survey in the late 19th century, and the project was authorized on April 23, 1904. In the 18th century, Shoshone territory extended beyond the Snake River Plain, extending over the Continental Divide into the upper Missouri River watershed and even further north into Canada. Uniting, they form a small stream, which, at an altitude of two miles above sea level, begins its arduous journey...to the Pacific" (p. 309). The problem was to find the longest branch in the Two Ocean Plateau, which is thoroughly crisscrossed with streams. From elevations of 10,000 feet (3,000 metres) the river descends to 300 feet (90 metres) at its outflow into the Columbia. [11][12][13][14][15], Southwest of Rexburg, Idaho, the Snake is joined from the north by Henrys Fork. The reason for the Three Island Crossing was the better availability of grass and water access. After destroying the dam, salmon populations noticeably recovered. In that period, the largest average annual flow recorded was 84,190 cu ft/s (2,384 m3/s) in 1997, and the lowest was 27,100 cu ft/s (770 m3/s) in 1992. [102][103] On the western edge of the state, it is joined by the Boise River. [30] In places, water exits from rivers at rates of nearly 600 cubic feet per second (17 m3/s). Directly below the confluence, the river flows into Lower Granite Lake, formed by Lower Granite Dam, the uppermost dam of the Lower Snake River Project. Donald Mackenzie sailed the lower Snake River in 1811, and later explorers included Wilson Price Hunt of the Astor Expedition (who gave the river the name "Mad River"),[67] Ramsay Crooks, Francisco Payelle, John Grey, Thyery Goddin, and many others after the 1830s. In the 1960s and 1970s the U.S. Army Corps of Engineers built four dams and locks on the lower Snake River to facilitate shipping. [100], Aside from aquatic species, much of the Snake River watershed supports larger animals including numerous species of mammals, birds, amphibians, and reptiles. [101], The Snake River watershed includes a diversity of vegetation zones both past and present. Salmon can travel up the Snake River as far as Hells Canyon Dam, using the fish passage facilities of the four lower Snake River dams, leaving the Clearwater, Grande Ronde and Salmon river to sustain spawning salmon. Pollutant levels in Hells Canyon upstream of the Salmon River confluence, including that of water temperature, dissolved nutrients, and sediment, are required to meet certain levels. Shoshone Indians referred to some parts of the stream as "Yampa-pah," meaning "stream where the Yampa grows" (yampa is a food plant) and later as "Po-og-way" meaning "road river" (a reference to the Oregon Trail, which followed sections of the river) or, less often, "sagebrush river.". By the middle 19th century, the Oregon Trail had become well established, bringing numerous settlers to the Snake River region. [106] Because much of the electricity in the Northwest comes from dams, removing the four dams would create a hole in the energy grid that would not be immediately replaceable. There are many reasons why Sockeye Salmon in the Snake River are reduced in number. It receives the Hoback and Greys Rivers before entering Palisades Reservoir, where the Salt River joins at the mouth of Star Valley.