{{For|Lake Eleanor in Ventura County, California|Banning Dam}} {{Use American English|date=February 2026}} {{Infobox body of water | name = Lake Eleanor | image = Lake_eleanor, ca.jpg | caption = Lake Eleanor's eastern shore in 2016, as viewed from a small peninsula | image_bathymetry = | caption_bathymetry = | location = Yosemite National Park, Tuolumne County, California, United States | coords = {{coord|37.9779767|N|119.8790685|W|format=dms|type:waterbody_region:US-CA_source:gnis|display=inline,title}} <ref name="gnis">*{{cite gnis|259830|Lake Eleanor}}</ref> | type = reservoir | inflow = Eleanor Creek | outflow = | catchment = | basin_countries = United States | length = | width = | area = {{convert|953|acre|km2|1}} | depth = | max-depth = | volume = {{convert|26100|acre.ft|km3|0}} | residence_time = | shore = | elevation = {{convert|4657|ft|0}} | islands = | cities = | frozen = <!-- Map --> | pushpin_map = California#USA | pushpin_label_position = | pushpin_map_alt = Location of Lake Eleanor in California, USA. | pushpin_map_caption = <!-- Below --> | website = | reference = }}
'''Lake Eleanor''' is a reservoir located in the northwestern backcountry of Yosemite National Park at an altitude of {{convert|4657|ft|m}}. The reservoir has a capacity of {{convert|26,100|acre.ft|m3}} and a surface area of 953 acres (3.9 km<sup>2</sup>).
==Geography== The reservoir is situated in a glacier carved valley at an elevation of {{convert|4600|-|4700|ft}}. Prior to flooding, a smaller lake of approximately {{convert|1.5|x|0.5|mi}} and {{convert|200|ft}} deep existed in the valley. The lake was fed by three streams, Kibbie Creek, Eleanor Creek, and Frog Creek. Before being clearcut, the valley floor was moderately to densely forested with a yellow pine forest consisting primarily of Jeffrey and ponderosa pines, with scatterings of incense cedar, white fir, and black oak. Manzanita and other shrub species made up the understory, and willow and other wetland species existed in the marshy areas around the lake and streams.<ref name="carpenter">{{cite journal |last1=Carpenter |first1=Scott L. |last2=Kirn |first2=Laura A. |title=Underwater but Not All Wet: The 1985 Lake Eleanor Archaeological Survey |journal=Articles of the SCA Proceedings |date=1988 |volume=1 |pages=189–215 |url=https://scahome.org/download/proceedings/Proceedings.01Carpenter.pdf |accessdate=21 March 2020 |format=PDF}}</ref>
==History== An archeological survey done of the valley in 1985 while the reservoir was drained for maintenance provided evidence of prehistoric occupation of the valley. Due to the limited time of the study and the nature of working in the sediment of a reservoir, the extent of occupation was unable to be assessed.<ref name="carpenter" />
Settlement of Lake Eleanor valley by Europeans began in the mid-1800s. In the late 1800s, two homestead patents were taken out in the valley, one by Hermann Wolfe on the south shore and another by Horace J. Kibbe on the north shore,<ref name="carpenter" /> which he occupied until 1913.<ref name="NPS">{{cite journal |last1=National Park Service |title=Reports on file 1906-1915 |journal=Report of the Acting Superintendent of the Yosemite National Park to the Secretary of the Interior |publisher=Yosemite Research Library, Yosemite National Park}}</ref>
==Dam construction== The current lake was formed in 1918 by damming Eleanor Creek as part of the Hetch Hetchy Reservoir system,<ref name="carpenter" /> constructed to supply water and power to the city of San Francisco. The original smaller, natural lake was also named "Eleanor"<ref name="carpenter" /> after the daughter of Josiah Whitney, leader of the California Geological Survey in the 1860s.
'''Lake Eleanor Dam''' (National ID # CA00121) stands as a concrete multiple arch dam with a height of {{convert|68|ft|m}} and a length of {{convert|1260|ft|m}}. This first stage of the Hetch Hetchy project was built for year-round hydroelectric power generation, which was then sold to help finance construction of the larger O'Shaughnessy Dam, completed in 1923.<ref name="carpenter" />
That dams were planned for a valley in Yosemite National Park caused significant opposition. One of the most potent opponents was the Sierra Club and its founding President, John Muir. After two vetoes by Theodore Roosevelt, on December 19, 1913, Woodrow Wilson signed the Raker Act permitting construction. It began in 1914.
The remote location dictated the use of an unusual multiple-arch structure here. It dramatically minimized the amount of concrete used in comparison with a gravity dam. Even more unusual, the concrete arches were elliptical rather than circular, the only multiple-arch dam ever built this way.<ref>Building the Ultimate Dam: John S. Eastwood And the Control of Water in the West, by Donald Conrad Jackson, page 297</ref> Chief designer for the San Francisco Board of Public Works Michael O'Shaughnessy and hydraulic structural engineer R.P. McIntosh were primarily responsible for the design.<ref>Proceedings of the American Society of Civil Engineers, Volume 48, Part 1, by American Society of Civil Engineers, February, 1922</ref>
Still owned and operated by the city of San Francisco, the lake now provides opportunities for angling, hiking, and camping.
==Climate== {{Weather box |single line= yes |width = auto |location= Eleanor Lake, California |Jan record high F=75 |Feb record high F=73 |Mar record high F=79 |Apr record high F=83 |May record high F=87 |Jun record high F=99 |Jul record high F=101 |Aug record high F=103 |Sep record high F=98 |Oct record high F=92 |Nov record high F=80 |Dec record high F=77 |year record high F= |Jan high F=47.1 |Feb high F=49.1 |Mar high F=53.5 |Apr high F=59.5 |May high F=66.2 |Jun high F=75.0 |Jul high F=85.3 |Aug high F=85.4 |Sep high F=79.4 |Oct high F=68.0 |Nov high F=57.9 |Dec high F=49.7 |year high F=
|Jan mean F=36.3 |Feb mean F=38.1 |Mar mean F=41.7 |Apr mean F=47.7 |May mean F=54.1 |Jun mean F=61.7 |Jul mean F=71.0 |Aug mean F=70.3 |Sep mean F=64.3 |Oct mean F=54.0 |Nov mean F=45.2 |Dec mean F=38.9 |year mean F=
|Jan low F=25.4 |Feb low F=27.3 |Mar low F=30.0 |Apr low F=36.0 |May low F=41.9 |Jun low F=48.4 |Jul low F=56.7 |Aug low F=55.1 |Sep low F=49.1 |Oct low F=40.1 |Nov low F=32.4 |Dec low F=28.1 |year low F=
|Jan record low F=-7 |Feb record low F=-12 |Mar record low F=1 |Apr record low F=13 |May record low F=22 |Jun record low F=24 |Jul record low F=35 |Aug record low F=34 |Sep record low F=29 |Oct record low F=20 |Nov record low F=10 |Dec record low F=-2 |year record low F=
|precipitation colour= green |Jan precipitation inch=7.71 |Feb precipitation inch=7.16 |Mar precipitation inch=5.93 |Apr precipitation inch=3.50 |May precipitation inch=1.91 |Jun precipitation inch=0.71 |Jul precipitation inch=0.09 |Aug precipitation inch=0.09 |Sep precipitation inch=0.51 |Oct precipitation inch=2.27 |Nov precipitation inch=4.17 |Dec precipitation inch=7.45 |year precipitation inch=
|Jan snow inch=30.3 |Feb snow inch=26.2 |Mar snow inch=32.2 |Apr snow inch=10.2 |May snow inch=1.6 |Jun snow inch=0.1 |Jul snow inch=0.0 |Aug snow inch=0.0 |Sep snow inch=0.1 |Oct snow inch=1.5 |Nov snow inch=6.7 |Dec snow inch=24.1 |year snow inch=
|unit precipitation days= 0.01 in |Jan precipitation days=10 |Feb precipitation days=10 |Mar precipitation days=10 |Apr precipitation days=8 |May precipitation days=7 |Jun precipitation days=3 |Jul precipitation days=1 |Aug precipitation days=1 |Sep precipitation days=2 |Oct precipitation days=5 |Nov precipitation days=6 |Dec precipitation days=9 |year precipitation days=
|source 1= Western Regional Climate Center<ref>{{Cite web |url= http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca4679|title= Lake Eleanor, California - Climate Summary - Temperature|publisher= Western Regional Climate Center|accessdate=June 21, 2012 }}</ref><ref>{{Cite web |url= http://www.wrcc.dri.edu/cgi-bin/cliGCStP.pl?ca4679|title= Lake Eleanor, California - Climate Summary - Precipitation|publisher= Western Regional Climate Center|accessdate=June 21, 2012 }}</ref> }}
thumb|center|Lake Eleanor in 1896, viewed from the tram near its outlet, looking northeast.
==See also== *List of lakes in California
==References== {{Reflist}} *''California Place Names'', Erwin Gudde (University of California Press, 2004) {{ISBN|0-520-24217-3}}
==External links== * [http://cdec.water.ca.gov/cgi-progs/stationInfo?station_id=ENR California Department of Water Resources: Lake Eleanor] {{Webarchive|url=https://web.archive.org/web/20080117130257/http://cdec.water.ca.gov/cgi-progs/stationInfo?station_id=ENR |date=2008-01-17 }}
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{{DEFAULTSORT:Eleanor}} Category:Reservoirs in Tuolumne County, California Category:Lakes of Yosemite National Park Category:Hetch Hetchy Project Category:Tuolumne River Eleanor