Editing Snake River (section)

===Irrigation===
Most travelers on the Oregon Trail regarded the arid Snake River Plain as an obstacle to be crossed, not a land to be settled. This began to change with the Boise gold strikes, where the demands of the mining industry and the difficulty of importing goods set off an agricultural boom in the Boise Valley.<ref name="Long 2021"/><ref name="Petersen and Reed"/>{{rp|45}} By the 1880s, settlers also came to the upper Snake River north of Idaho Falls, where fertile, sandy soils presented ideal conditions for the iconic [[russet potato]] ("Idaho potato").<ref name="Idaho Falls Power">{{cite web|url=https://www.idahofallsidaho.gov/DocumentCenter/View/495/Idaho-Falls-Power-History-PDF?bidId=|title=Idaho Falls Power – History|publisher=City of Idaho Falls|date=|accessdate=December 9, 2023}}</ref> The dry climate made irrigation necessary, and numerous private irrigation companies were formed.<ref name="Boise irrigation">{{cite web|url=https://history.idaho.gov/wp-content/uploads/0171.pdf|title=Early Irrigation Canals Pre-Project Ventures|publisher=Idaho State Historical Society|work=Idaho State Historical Society Reference Series|accessdate=December 9, 2023}}</ref> Private canal systems around Boise and Idaho Falls saw some success, but all the easily farmable land was soon developed, and they could not raise the capital for further expansion. In addition, low water by late summer posed a challenge to farmers, and the irrigation companies could not afford to build dams to provide water storage.<ref>{{cite web|url=https://www.nps.gov/articles/idaho-arrowrock-dam.htm|title=Idaho: Arrowrock Dam|publisher=U.S. National Park Service|date=January 13, 2017|accessdate=December 9, 2023}}</ref>

[[Image:-IDAHO-A-0009-_American_Falls_Dam_(5440020069).jpg|thumb|right|280px|The first [[American Falls Dam]] (1927, rebuilt 1978) was constructed to store water for the federal [[Minidoka Project]].|alt=View across a river, with a concrete dam on the left and a bridge on the right with a town on the opposite bank.]]
With many private irrigation companies verging on insolvency, the federal government began to explore programs assisting agricultural development. The 1894 [[Carey Act]] granted large tracts of dry federal land to western states, which then sold the land to farmers and solicited private investors to organize irrigation districts. Investors would then recoup their capital by selling water rights to farmers.<ref name="Idaho irrigation"/> Irrigation plans were reviewed by engineers, who determined the economic feasibility of the projects. Although the Carey Act saw little success in most states, it greatly benefited Idaho. Some 60&nbsp;percent of all lands developed under the Carey Act were in Idaho, and almost all of that utilized Snake River water.<ref name="Idaho irrigation">{{cite web|url=https://history.idaho.gov/wp-content/uploads/0260_Irrigation-in-Idaho-1.pdf|title=Irrigation in Idaho|publisher=Idaho State Historical Society|work=Idaho State Historical Society Reference Series|date=Jun 1971|accessdate=December 9, 2023}}</ref>

[[I. B. Perrine]], who homesteaded near Shoshone Falls in the 1880s, went on to develop one of the most successful Carey Act projects. In 1900 Perrine filed a claim for water from the Snake River, and backed by significant private capital, oversaw the construction of [[Milner Dam]] and a canal system to irrigate some {{convert|250000|acre|ha}} of the Snake River Plain.<ref name="Milner Dam"/> Completed in 1905, the project was an immediate success. The rapid transformation of the barren landscape into productive farmland led to the moniker "[[Magic Valley]]", and led to massive growth of the city of Twin Falls.<ref>{{cite web|url=https://twinfallscanal.com/milner-dam/|title=History of Milner Dam|publisher=Twin Falls Canal Company|date=|accessdate=December 10, 2023}}</ref><ref>{{cite web|url=https://www.tfid.org/DocumentCenter/View/422/History-of-Twin-Falls?bidId=|title=The History of Twin Falls|publisher=City of Twin Falls|date=|accessdate=December 10, 2023}}</ref>  During certain times of the year, almost all the Snake River's flow was diverted at Milner Dam, and since then, Shoshone Falls has regularly run dry in the summer.<ref>{{cite web|url=https://www.idahoconservation.org/blog/the-power-of-water-making-the-magic-valley-magic/|title=The power of water: Making the Magic Valley magic|publisher=Idaho Conservation League|author=Urbanek, Abby|date=March 7, 2023|accessdate=December 19, 2023}}</ref> The [[Idaho State Historical Society]] writes that "Perrine’s venture contrasted remarkably with private canal company failures that led to congressional provision for federal reclamation projects after 1902. As a rare successful example of state supervised private irrigation development provided for in [the Carey Act] of 1894, Milner Dam and its canal system have national significance in agricultural history."<ref name="Milner Dam">{{cite web|url=https://history.idaho.gov/wp-content/uploads/0497_Milner-Dam.pdf|title=Milner Dam|publisher=Idaho State Historical Society|work=Idaho State Historical Society Reference Series|year=1985|accessdate=December 10, 2023}}</ref>

With the creation of the Reclamation Service (now the [[Bureau of Reclamation]]) in 1902, the federal government began to play a more direct role in water resources development. The expansive [[Minidoka Project]] was the first federal reclamation project in Idaho.<ref name="NPS Minidoka">{{cite web|url=https://www.nps.gov/articles/idaho-minidoka-dam.htm|title=Idaho: Minidoka Dam|publisher=U.S. National Park Service|date=|accessdate=December 11, 2023}}</ref> Starting with [[Minidoka Dam]] in 1906, the project would grow over the next few decades to include major reservoirs at [[Jackson Lake Dam|Jackson Lake]], [[American Falls Dam|American Falls]] and [[Island Park Dam|Island Park]], and a large network of canals and pump stations. The Minidoka Project would eventually bring water to a million acres (2,500&nbsp;km<sup>2</sup>) of the Magic Valley.<ref name="NPS Minidoka"/> During World War II, many [[Minidoka National Historic Site|Japanese Americans interned at Minidoka]] were made to work on the project.<ref name="NPS Minidoka"/> The [[Boise Project]], which would ultimately water {{convert|500000|acre|ha}} in and around the Boise Valley, was another major early reclamation undertaking. At its completion, [[Arrowrock Dam]] (1915) on the Boise River was the tallest dam in the world, and its construction process was an important prototype for future federal projects such as [[Hoover Dam]].<ref>{{cite web|url=https://www.intermountainhistories.org/items/show/114|title=Arrowrock Dam, Engineering Innovation and Building Block to Boise's Expansion|publisher=Intermountain Histories|author=Hyde, Luke|accessdate=December 19, 2023}}
</ref><ref>{{cite web|url=https://www.usbr.gov/projects/pdf.php?id=74|title=The Boise Project|author=Simonds, Joe|work=Bureau of Reclamation History Program|year=1997|publisher=U.S. Bureau of Reclamation|accessdate=December 19, 2023}}</ref>

[[Image:Palisades_Dam_(4306260425).jpg|thumb|left|[[Palisades Dam]] (1956) provides irrigation and flood control for the Snake River upstream of Idaho Falls.|alt=Aerial view looking upstream at an earthen dam and a reservoir stretching off into a mountain valley in the distance]]
Starting around the 1950s, farmers made heavy use of the Snake River aquifer, bringing large new areas into production.<ref name="Idaho irrigation"/> Surface water development also increased with projects such as [[Cascade Dam]] (1948) and [[Anderson Ranch Dam]] (1950), which provided additional storage for the Boise Project. [[Palisades Dam]] was built in 1956, providing flood control and irrigation for the Snake River above Idaho Falls, an area which the Bureau of Reclamation had previously overlooked.<ref>{{cite web|url=https://www.intermountainhistories.org/items/show/92|title=The Palisades Dam: Irrigation of the Snake River|author=Franzen, Josh|publisher=Intermountain Histories|accessdate=December 19, 2023}}
</ref> Near Rexburg, the [[Teton Dam]] was also built to provide water for this area. In 1976, the Teton Dam failed catastrophically, killing eleven people and causing at least $400 million in damage along the Henrys Fork and Snake Rivers.<ref>{{cite web|url=https://damfailures.org/case-study/teton-dam-idaho-1976/|title=Case Study: Teton Dam (Idaho), 1976|publisher=Association of State Dam Safety Officials|date=|accessdate=January 10, 2024}}</ref> The political fallout from this disaster marked the end of large new irrigation developments not only for the Snake River system, but for the Bureau of Reclamation as a whole.<ref>{{cite book|title=The Bureau of Reclamation: From Developing to Managing Water, 1945-2000|publisher=U.S. Government Printing Office|isbn=9780160913648|year=2013|url=https://books.google.com/books?id=65sl1m7QntkC}}</ref> {{rp|839–841}}

Agriculture has significantly impacted water quality in the Snake River upstream of Hells Canyon. Water removed from the river for irrigation becomes contaminated with chemical fertilizers and manure, and percolates into the Snake River Aquifer. Pollutants collect in the groundwater and eventually enter the river via spring flows.<ref>{{cite web
|url=http://imnh.isu.edu/digitalatlas/hydr/concepts/gwater/gwr.htm
|title=Groundwater Resources
|work=Digital Atlas of Idaho
|publisher=Idaho Museum of Natural History
|access-date=October 11, 2009
|archive-date=June 25, 2010
|archive-url=https://web.archive.org/web/20100625013845/http://imnh.isu.edu/digitalatlas/hydr/concepts/gwater/gwr.htm
|url-status=live
}}</ref> Excess nitrogen, phosphorus and bacterial loads occur in many locations across southern Idaho.<ref>{{cite web|url=https://www.idahoconservation.org/blog/pollution-science-understanding-the-building-blocks-for-restoring-idahos-snake-river/|title=Pollution Science: Understanding the building blocks for restoring Idaho's Snake River|publisher=Idaho Conservation League|author=Black, Lexi|date=January 26, 2024|accessdate=February 3, 2024}}</ref> Large [[algae bloom]]s are a recurring issue in summer.<ref>{{cite web
 |url         = http://www.cwnp.org/naturalist/snakealgae.html
 |title       = Pollution of the Snake River
 |publisher   = Central Washington Native Plants
 |work        = Ecology and Conservation
 |access-date  = October 11, 2009
|url-status     = dead
 |archive-url  = https://web.archive.org/web/20091023133751/http://www.cwnp.org/naturalist/snakealgae.html
 |archive-date = October 23, 2009
}}</ref> The [[U.S. Environmental Protection Agency]] has established water quality guidelines for Snake River flows entering Hells Canyon, which cover bacteria, mercury, excess nutrients, pesticides, sediments and water temperature. Implementation of the guidelines include [[Best management practice for water pollution|best management practices]] for agriculture and forestry, and regular water quality monitoring.<ref>{{cite web|url=https://attains.epa.gov/attains-public/api/documents/actions/IDEQ/10745/106704|title=Snake River - Hells Canyon Total Maximum Daily Load (TMDL)|publisher=U.S. Environmental Protection Agency|year=2004|accessdate=January 31, 2024}}</ref>