{{Use American English|date=July 2025}} {{Infobox dam | name = Anderson Ranch Dam | image = Anderson Ranch Dam and Reservoir.JPG | image_size = 240px | image_caption = View from southwest in August 2009 | dam_crosses = South Fork of Boise River | res_name = Anderson Ranch Reservoir | country = United States | location = Elmore County, Idaho | location_map = USA#Idaho | location_map_size = | location_map_caption = Location in the United States##Location in Idaho | operator = U.S. Bureau of Reclamation<ref name="npdp"/> | dam_length = {{convert|1350|ft|0}}<ref name="npdp"/> | dam_height = {{convert|456|ft}}<ref name="npdp"/> | dam_width_base = | construction_began = 1941<ref name=npsard/> | opening = {{start date and age|1950}} | cost = | res_capacity_total = {{convert|503500|acre.ft|km3|sigfig=3}}<ref name="npdp"/> | res_catchment = {{convert|960|sqmi|km2|sigfig=3}}<ref name="npdp"/> | res_surface = {{convert|4815|acre|km2|sigfig=3}}<ref name="npdp"/> | res_elevation = {{convert|4190|ft|abbr=on|-1}} AMSL | coordinates = {{coord|43|21|27|N|115|26|55|W|display=inline,title|region:US_type:landmark}} | res_tidal_range = | plant_operator = | plant_commission = 1951 (1986)<ref name=npsard/> | plant_decommission = | plant_type = | plant_turbines = 2 x 20 MW<ref name=npsard/> | plant_capacity = 40 MW | plant_annual_gen = | website = |extra = center|240px|Columbia River Basin }} '''Anderson Ranch Dam''' is an earth rockfill type dam in the western United States, on the South Fork of the Boise River in southwestern Idaho. In&nbsp;Elmore County northeast of Mountain Home, it is several miles north of U.S.&nbsp;Route&nbsp;20 and operated by the U.S.&nbsp;Bureau of Reclamation.

When completed {{Time ago|1950}} in 1950, Anderson Ranch was the tallest dam of its type in the world.<ref>{{Cite web |url=http://www.usbr.gov/projects/Facility.jsp?fac_Name=Anderson+Ranch+Dam |title=USBR.gov |access-date=2012-02-10 |archive-url=https://web.archive.org/web/20111112085814/http://www.usbr.gov/projects/Facility.jsp?fac_Name=Anderson+Ranch+Dam |archive-date=2011-11-12 |url-status=dead }}</ref> Its primary purpose is to provide irrigation water for agriculture, with a secondary purpose of hydroelectric power. Its&nbsp;generating capacity was increased from 27 to 40 MW in&nbsp;1986.<ref name=npsard/><ref name="npdp">[http://npdp.stanford.edu/DamDirectory/DamDetail.jsp?npdp_id=ID00279 Anderson Ranch Dam] {{Webarchive|url=https://web.archive.org/web/20110716112550/http://npdp.stanford.edu/DamDirectory/DamDetail.jsp?npdp_id=ID00279 |date=2011-07-16 }}, NPDP Dam Directory</ref> Its&nbsp;reservoir has a spillway elevation of {{convert|4196|ft|-1}} above sea&nbsp;level.

The construction of the dam began in 1941 and experienced numerous challenges with materials, fuel, and labor shortages during World War II. Work was halted for over nine months beginning in late December 1942. The Reclamation Act of 1902 had racial exclusions on labor which were strictly adhered to until Congress changed the law in 1943. This allowed Japanese American internees to work on Reclamation projects; Anderson Ranch utilized internees from the Minidoka War Relocation Center, northeast of Twin Falls.<ref name=npsard>[https://web.archive.org/web/20120415100747/http://www.nps.gov/history/nr/travel/ReclamationDamsAndWaterProjects/Anderson_Ranch_Dam_and_Powerplant.html National Park Service] - history - Anderson Ranch Dam & Powerplant, Idaho - accessed 2012-02-09</ref>

The South Fork of the Boise River originates in the Smoky Mountains north of Fairfield. Its watershed includes portions of the Smoky Mountains, Soldier Mountains, Boise National Forest, and Sawtooth National Forest. Below the dam, the South Fork flows northwestward into the reservoir behind the concrete Arrowrock Dam, completed in 1915.

The Bureau of Reclamation and Idaho Water Resource Board are working on raising the dam by {{convert|6|ft|spell=in}}, resulting in approximately {{convert|29000|acre.ft|m3|sigfig=3}} of new storage space.<ref>[https://www.usbr.gov/pn/studies/boisefeasibility/andersonraise/index.html] U.S. Bureau of Reclamation, Anderson Ranch Dam Raise - accessed 2022-07-18</ref> The&nbsp;design is scheduled for completion in the summer of&nbsp;2024.<ref>[https://www.usbr.gov/pn/studies/boisefeasibility/andersonraise/milestones.html] U.S. Bureau of Reclamation, Anderson Ranch Dam Raise Milestones - accessed 2022-07-18</ref>

==References== {{Reflist}}

==External links== {{Portal|Water|Renewable energy}} *[https://web.archive.org/web/20111112085814/http://www.usbr.gov/projects/Facility.jsp?fac_Name=Anderson+Ranch+Dam USBR.gov ] - Bureau of Reclamation - Anderson Ranch Dam *[http://www.idwr.idaho.gov/water/stream_dam/dams/Anderson.htm Idaho Dept. of Water Resources] - Anderson Ranch Dam *[https://web.archive.org/web/20130305063744/http://www.usbr.gov/pn/hydromet/boipaytea.html USBR.gov] - major storage reservoirs in the Boise & Payette River basins - current levels & flows

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{{DEFAULTSORT:Anderson}} Category:Dams in Idaho Category:Reservoirs in Idaho Category:Hydroelectric power plants in Idaho Category:Buildings and structures in Elmore County, Idaho Category:United States Bureau of Reclamation dams Category:Dams completed in 1950 Category:Energy infrastructure completed in 1950 Category:Boise Project