Editing Snake River (section)

==Course==
The Snake River starts to the north of [[Two Ocean Pass]] near the southern border of [[Yellowstone National Park]], about {{convert|9200|ft|m}} above sea level in the Rocky Mountains of [[Wyoming]].<ref>{{cite web |title=Map of Start of Snake River |url=https://topoquest.com/map.php?lat=44.13500&lon=-110.22064&datum=nad83&zoom=4&map=auto&coord=d&mode=zoomin&size=m&cross=on |website=TopoQuest |access-date=December 23, 2024}}</ref> The river descends west through the high mountains of the [[Teton Wilderness]] meeting the [[Lewis River (Wyoming) | Lewis River]] and continuing south into [[Jackson Lake (Wyoming)|Jackson Lake]] in [[Grand Teton National Park]], a natural glacial lake enlarged by [[Jackson Lake Dam]].<ref>{{cite web |title=Snake River Headwaters and Watershed |url=https://www.rivers.gov/river/snake-river-headwaters |website=rivers.org |access-date=December 23, 2024}}</ref> Joined by [[Pacific Creek (Teton_County, Wyoming) | Pacific Creek]] and [[Buffalo Fork (Wyoming)| Buffalo Fork]] below the dam, it meanders southward through the alpine valley of [[Jackson Hole]] situated on the plain in front of the [[Teton Range]] to the west and the [[Gros Ventre Range]] to the east. 

Below the town of [[Jackson, Wyoming|Jackson]] it forms the [[Snake River Canyon (Wyoming)|Snake River Canyon of Wyoming]], turns west and crosses into [[Idaho]], where the [[Palisades Dam]] forms [[Palisades Reservoir]]. From there it flows northwest through Swan Valley to join the [[Henrys Fork (Snake River tributary)|Henrys Fork]] on an [[alluvial plain]] near [[Rexburg, Idaho|Rexburg]].<ref name="TNM">{{cite web|url=https://apps.nationalmap.gov/downloader/|title=National Hydrography Dataset high-resolution flowline data from The National Map|publisher=U.S. Geological Survey|accessdate=December 15, 2023}}</ref> The Henrys Fork is sometimes called the "North Fork" of the Snake River,<ref name="GNIS Henrys Fork"/> while the section of the main Snake River above their confluence is sometimes called the "South Fork".<ref name="GNIS"/><ref>{{cite web|url=https://www.blm.gov/visit/south-fork-snake|title=South Fork of the Snake|publisher=U.S. Bureau of Land Management|date=|accessdate=January 15, 2024}}</ref>

Turning southwest, the river begins its long journey across the Snake River Plain, passing through [[Idaho Falls, Idaho|Idaho Falls]] and receiving the [[Blackfoot River (Idaho)|Blackfoot River]] from the left before entering the {{convert|20|mi|km|adj=on}}-long [[American Falls Reservoir]], formed by [[American Falls Dam]].<ref name="TNM"/> From [[American Falls, Idaho|American Falls]] it turns west, flowing through [[Minidoka Dam]] and [[Milner Dam]], where large volumes of water are diverted for irrigation.<ref>{{cite web|url=https://www.waterdistrict1.com/media/uabos05r/wd01-procedures-manual-4-12-2023.pdf|title=Concepts, practices and procedures used to distribute water within Water District #1, Upper Snake River Basin, Idaho|author=Olenichak, Tony|date=April 14, 2023|publisher=Idaho Water District 1|accessdate=January 27, 2024}}</ref> Below Milner Dam it enters the [[Snake River Canyon (Idaho)|Snake River Canyon of Idaho]], where the river narrows, forming rapids and waterfalls. In the {{convert|70|mi|km|adj=on}} stretch between Milner Dam and the confluence with the [[Malad River (Gooding County, Idaho)|Malad River]] near [[Hagerman Fossil Beds National Monument]], the Snake River descends a total of {{convert|1300|ft|m}} over a series of cataracts and rapids, chief of which include [[Caldron Linn (Idaho)|Caldron Linn]], [[Twin Falls (Idaho)|Twin]], [[Shoshone]], [[Pillar Falls|Pillar]], Auger, and [[Salmon Falls (Snake River)|Salmon Falls]].<ref name="USGS Kimberly">{{Cite web |url=https://topoquest.com/map-detail.php?usgs_cell_id=23558|title=U.S. Geological Survey Topographic Map: Kimberly, Idaho quad |author=U.S. Geological Survey |publisher=TopoQuest |access-date=January 27, 2024}}</ref><ref name="USGS Twin Falls">{{Cite web |url=https://topoquest.com/map-detail.php?usgs_cell_id=46106|title=U.S. Geological Survey Topographic Map: Twin Falls, Idaho quad |author=U.S. Geological Survey |publisher=TopoQuest |access-date=January 27, 2024}}</ref><ref name="USGS Jerome">{{Cite web |url=https://topoquest.com/map-detail.php?usgs_cell_id=22551|title=U.S. Geological Survey Topographic Map: Jerome, Idaho quad |author=U.S. Geological Survey |publisher=TopoQuest |access-date=January 27, 2024}}</ref><ref name="USGS Hagerman">{{Cite web |url=https://topoquest.com/map-detail.php?usgs_cell_id=18897|title=U.S. Geological Survey Topographic Map: Hagerman, Idaho quad |author=U.S. Geological Survey |publisher=TopoQuest |access-date=January 27, 2024}}</ref> [[Idaho Power]] operates several small hydroelectric plants along this stretch of the river.<ref name="Idaho Power hydro plants"/> The largest single drop is {{convert|212|ft|m|adj=on}} [[Shoshone Falls]], which in the spring flows with such force that 19th-century writers called it the "Niagara of the West".<ref name="Williamson 1997">{{cite book|author=Williamson, Darcy|title=River Tales of Idaho|publisher=Caxton Press|isbn=9780870045318|year=1997|url=https://books.google.com/books?id=yYmbiFgrg5kC}}</ref>{{rp|89–90}}

[[Image:Morley Nelson Snake River Birds of Prey NCA (9423934512).jpg|thumb|left|280px|The Snake River flows through canyons in the [[Morley Nelson Snake River Birds of Prey National Conservation Area]], south of Boise.|alt=Wide view over a river valley surrounded by cliffs and shrub land]]
The Snake River continues flowing west, through the [[C. J. Strike Reservoir]] where it is joined from the left by the [[Bruneau River]], then through the [[Morley Nelson Snake River Birds of Prey National Conservation Area]] before entering farmland on the western side of Idaho's [[Treasure Valley]].{{#tag:ref|The Treasure Valley was historically known as the Boise Valley or Snake River Valley, and was only given the modern name in 1959.<ref>{{cite news|url=https://www.ktvb.com/article/news/local/208/how-treasure-valley-got-its-name-oregon-trail/277-cc3131bd-6798-43ac-80f6-85818b911e55|title=How a Caldwell businessman in 1959 gave the Treasure Valley its name|work=KTVB 7|author=Holmes, Brian|date=October 22, 2021|accessdate=January 27, 2024}}</ref> Uses of the name "Boise Valley" in this article, in a historical context, refer to the Treasure Valley.|group=n}} Passing {{convert|30|mi|km}} west of [[Boise, Idaho|Boise]], it crosses briefly into [[Oregon]] before turning north to form the Oregon–Idaho border.<ref name="TNM"/> It is joined by several major tributaries in quick succession – the [[Boise River]] from the right, the [[Owyhee River|Owyhee]] and [[Malheur River]]s from the left, the [[Payette River|Payette]] and [[Weiser River]]s from the right near [[Ontario, Oregon]], then the [[Powder River (Oregon)|Powder]] and [[Burnt River (Oregon)|Burnt River]]s from the left.<ref name="TNM"/> Continuing north, the river enters [[Hells Canyon]], which slices between the Rocky Mountains of Idaho and the [[Blue Mountains (Pacific Northwest)|Blue Mountains]] of Oregon and Washington.<ref name="TNM"/> The Hells Canyon Hydroelectric Complex includes the [[Brownlee Dam|Brownlee]], [[Oxbow Dam|Oxbow]] and [[Hells Canyon Dam]]s in the upper reaches of the canyon.<ref>{{cite web|url=https://docs.idahopower.com/pdfs/relicensing/hellscanyon/hellspdfs/hc_licenseapp.pdf|title=Hells Canyon Complex FERC No. 1971 License Application|publisher=Idaho Power|year=|accessdate=January 27, 2024}}</ref> Since its construction in 1967, Hells Canyon Dam has been the upriver limit for migrating salmon; in the past, salmon swam as far upriver as Shoshone Falls.<ref>{{cite web|url=https://critfc.org/tribal-treaty-fishing-rights/policy-support/columbia-river-treaty/area-blocked-salmon-columbia-basin/|title=Columbia Basin Passage Barriers|publisher=Columbia River Inter-Tribal Fish Commission|date=|accessdate=January 27, 2024}}</ref>

Emerging from Hells Canyon Dam, the Snake surges northward through the [[Hells Canyon Wilderness (Oregon and Idaho)|Hells Canyon Wilderness]], where the majority of the river corridor is accessible only by boat and numerous [[International scale of river difficulty|Class III-IV]] rapids<ref>{{cite book|author=Stahl, Greg|title=Paddling Idaho: A Guide to the State's Best Paddling Routes|publisher=Falcon Guides|year=2016|isbn=9781493027088}}</ref>{{rp|128–131}} historically posed a major barrier to navigation.<ref>{{cite encyclopedia|url=https://www.oregonencyclopedia.org/articles/hells-canyon/|title=Hells Canyon|author=Sowards, Adam M.|publisher=Oregon Historical Society|encyclopedia=Oregon Encyclopedia|date=August 9, 2023|accessdate=February 2, 2024}}</ref> Today, the canyon and the surrounding [[Hells Canyon National Recreation Area]] are a popular location for whitewater boating, fishing, horseback riding and backpacking.<ref>{{cite web|url=https://www.fs.usda.gov/detail/wallowa-whitman/specialplaces/?cid=stelprdb5227248|title=Wild and Scenic Snake River- Trip Planning|publisher=U.S. Forest Service|date=|accessdate=January 15, 2024}}</ref><ref name="Snake NWSR"/> With the adjacent [[Seven Devils Mountains]] rising up to {{convert|8000|ft|m}} above the river, Hells Canyon is one of the deepest canyons in North America, almost one-third deeper than the [[Grand Canyon]].<ref name="USFS Hells Canyon">{{cite web|url=https://www.fs.usda.gov/detail/wallowa-whitman/specialplaces/?cid=stelprdb5239080|title=Hells Canyon National Recreation Area - Fast Facts
|publisher=U.S. Forest Service|date=|accessdate=January 27, 2024}}</ref> Within the canyon it is joined from the left by the [[Imnaha River]], then from the right by its longest tributary, the [[Salmon River (Idaho)|Salmon River]]. Further north, it begins to form the Idaho–[[Washington (state)|Washington]] border, and receives the [[Grande Ronde River]] from the left.<ref name="TNM"/> From the end of Hells Canyon at [[Asotin, Washington]], it flows north to [[Lewiston, Idaho]], where it is joined from the right by the [[Clearwater River (Idaho)|Clearwater River]], its largest tributary by volume. The Snake then turns sharply west to enter Washington.<ref name="TNM"/>

The final stretch of the Snake River flows through steep-sided valleys in the [[Palouse Hills]] of southeast Washington. Near [[Lyons Ferry State Park]], it is joined from the left by the [[Tucannon River]], then from the right by the [[Palouse River]], which forms [[Palouse Falls]] about {{convert|8|mi|km}} upstream of its confluence with the Snake.<ref name="TNM"/> The Lower Snake River Project consists of four dams equipped with [[Lock (water navigation)|navigation locks]] – [[Lower Granite Dam|Lower Granite]], [[Little Goose Dam|Little Goose]], [[Lower Monumental Dam|Lower Monumental]] and [[Ice Harbor]] – which have transformed the once fast-flowing lower Snake River into a series of lakes, enabling heavy barges to travel between the Columbia River and the Port of Lewiston.<ref>{{cite web|url=https://portoflewiston.com/our-rivers/columbia-snake-river-system-eis-process/|title=Columbia-Snake River System|publisher=Port of Lewiston|date=|accessdate=January 27, 2024}}</ref> About {{convert|10|mi|km}} downstream from Ice Harbor Dam, the Snake empties into the Columbia River at [[Burbank, Washington]], southeast of the [[Tri-Cities, Washington|Tri-Cities]].<ref name="TNM"/> The confluence is located on [[Lake Wallula]], the impoundment behind [[McNary Dam]] on the Columbia,<ref name="TNM"/> {{convert|341|ft|m}} above sea level.<ref name="GNIS"/> From there, the Columbia River flows another {{convert|325|mi|km}} west to empty into the Pacific Ocean.<ref name="USGS Pasco">{{Cite web |url=https://topoquest.com/map-detail.php?usgs_cell_id=34340|title=U.S. Geological Survey Topographic Map: Pasco, Washington quad |author=U.S. Geological Survey |publisher=TopoQuest |access-date=January 27, 2024}}</ref>

===Discharge===
[[Image:Snake River, Hell's Canyon Road, Idaho - DPLA - f093871da3a1279fc4ada15e8ecd4bcf.jpg|thumb|right|The Snake River in Hells Canyon|alt=View of a river canyon surrounded by high, broken cliff faces]]
The [[U.S. Army Corps of Engineers]] has measured the [[Discharge (hydrology)|discharge]], or flow rate, of the Snake River at Ice Harbor Dam since 1962. The mean annual discharge for the 61-year period between 1962 and 2023 was {{convert|49580|cuft/s|m3/s}}, with a maximum recorded daily mean of {{convert|305000|cuft/s|m3/s|abbr=on}} on June 19, 1974, and a minimum daily mean of {{convert|2000|cuft/s|m3/s|abbr=on}} on November 29, 1961.<ref name=iceharbordam/> A historic June 1894 flood at the Ice Harbor site reached an estimated peak of {{convert|409000|cuft/s|m3/s|abbr=on}}.<ref name="Perkins 1973">{{cite report|title=Ice Harbor Dam, Snake River, Washington: Hydraulic Model Investigations|author=Perkins, L.Z.|year=1973|publisher=U.S. Army Corps of Engineers|url=https://books.google.com/books?id=8hDZC64tYf0C|page=1}}</ref> In terms of discharge, the Snake River is the twelfth largest river in the United States, and it contributes about one-fifth of the Columbia's total outflow into the Pacific.<ref name="USGSrivers">{{cite web |first = J. C. |last = Kammerer |url = http://pubs.usgs.gov/of/1987/ofr87-242/ |title = Largest Rivers in the United States |publisher =U.S. Geological Survey |date = May 1990 |access-date = April 1, 2008 |archive-url = https://web.archive.org/web/20170129040848/https://pubs.usgs.gov/of/1987/ofr87-242/ |archive-date = January 29, 2017 |url-status = live }}</ref>

The volume of the Snake River peaks in late spring and early summer as snow melts in the Rocky Mountains, and reaches its lowest point in the fall. Despite the numerous dams regulating its flow, its discharge into the Columbia remains highly seasonal.<ref name="Benke and Cushing 2005"/>{{rp|607}} At Ice Harbor Dam, the mean monthly discharge is highest in May and June at over {{convert|100000|cuft/s|m3/s|abbr=on}}, and lowest in September and October at less than {{convert|25000|cuft/s|m3/s|abbr=on}}.<ref name=iceharbordam/> Mean annual discharge also fluctuates significantly, from a record high of {{convert|86240|cuft/s|m3/s|abbr=on}} in 1965, to a low of {{convert|27890|cuft/s|m3/s|abbr=on}} in 1997.<ref name=iceharbordam/>

In southern Idaho, Snake River flows are significantly influenced by the [[Snake River Aquifer#Eastern Snake River Plain Aquifer|Eastern Snake River Plain Aquifer]]. One of the largest groundwater reserves in the US, the aquifer is founded in porous volcanic rock underneath the plain. It absorbs and stores large volumes of water from the Snake River in the eastern Plain to re-emerge further west as springs in the Snake River Canyon.<ref name="uppersnakeprovince">{{cite web
|url=http://www.nwcouncil.org/media/120275/1IntroOverview.pdf
|title=Upper Snake Province Assessment
|publisher=Northwest Watershed Council
|date=May 28, 2004
|access-date=January 6, 2024
|archive-date=October 18, 2021
|archive-url=https://web.archive.org/web/20211018074023/https://www.nwcouncil.org/sites/default/files/1IntroOverview.pdf
|url-status=live
}}</ref> Water from the [[lost streams of Idaho]], several rivers that disappear underground in the eastern Plain, travels through the aquifer to reach the Snake River,<ref>{{cite journal|url=http://www.ephemeroptera-galactica.com/pubs/pub_a/pubandrewsd1979p140.pdf|title=Distribution of Benthic Invertebrates in the Lost Streams of Idaho|author=Andrews, Douglas A. |author2=Minshall, G. Wayne|journal=The American Midland Naturalist|year=1979|volume=102|number=1|pages=140–148|doi=10.2307/2425075 |jstor=2425075 |accessdate=January 17, 2024}}</ref> as does excess irrigation water absorbed into the ground.<ref name="Snake River Plain hydrogeology"/> The major spring complexes at American Falls and Thousand Springs (near [[Hagerman, Idaho]]) keep the river flowing steadily even in the driest of summers.<ref name="ISU Snake River Plain aquifer">{{cite web|url=https://www.isu.edu/digitalgeologyidaho/srp-aquifer/|title=Snake River Plain aquifer|publisher=Idaho State University|accessdate=January 17, 2024}}</ref><ref>{{cite web|url=https://idwr.idaho.gov/wp-content/uploads/sites/2/legal/american-falls/AF-20020118-ESPA-Surface-Water-and-Groundwater-Interaction.pdf|title=Eastern Snake River Plain Surface and Ground Water Interaction|publisher=Idaho Department of Water Resources|date=January 18, 2002|accessdate=January 17, 2024}}</ref> At [[King Hill, Idaho|King Hill]], about {{convert|50|mi|km}} northwest of Twin Falls, water levels remain about {{convert|10000|cuft/s|m3/s|abbr=on}} for most of the year, increasing about 20&nbsp;percent during snowmelt and decreasing about 20&nbsp;percent with late summer irrigation diversions.<ref name="Snake River Plain hydrogeology">{{cite web|url=https://digitalatlas.cose.isu.edu/hydr/snakervr/srhyge.htm|title=Eastern Snake River Plain- Hydrogeology|publisher=Idaho State University|work=Digital Atlas of Idaho|date=|accessdate=January 17, 2024}}</ref><ref name="USGS Snake River at King Hill">{{cite web|url=https://wdr.water.usgs.gov/wy2013/pdfs/13154500.2013.pdf|title=USGS Gage #13154500 Snake River at King Hill, ID: Water-Data Report 2013|publisher=U.S. Geological Survey|work=National Water Information System|year=2013|accessdate=January 17, 2024}}</ref>

Despite its great length, the Snake River accumulates most of its water in the lower one-fourth of its course. By the time it reaches [[Hells Canyon Dam]], {{convert|247|mi|km}} from the mouth, the mean annual discharge is about {{convert|19000|cuft/s|m3/s|abbr=on}} – just over a third of the discharge at the mouth.<ref>{{cite web|url=https://wdr.water.usgs.gov/wy2013/pdfs/13290450.2013.pdf|title=USGS Gage #13213100 Snake River at Hells Canyon Dam: Water-Data Report 2013|publisher=U.S. Geological Survey|work=National Water Information System|year=2013|accessdate=February 3, 2024}}</ref> Just two downstream tributaries, the Clearwater and Salmon Rivers, contribute about half of the total flow of the Snake.<ref name="Benke and Cushing 2005"/>{{rp|607}}