Twain Harte Dam

{{Infobox dam

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| location_map = California#USA

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| location_map_alt = Location of the dam in California, USA.

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| opening = {{start date and age|1928}}

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Twain Harte Dam (National ID # CA00649) is a multiple arch dam in Tuolumne County, California. Its reservoir is Twain Harte Lake and it is located near Twain Harte, California.

Developers began building Twain Harte Dam in the summer of 1927.{{cite web |url=http://www.twainhartecc.com/history.aspx |title=Twain Harte Area History |author= |date=2014 |publisher=Twain Harte Area Chamber of Commerce |access-date=14 September 2014}} It was completed in 1928 and is owned by the Twain Harte Lake Association.{{cite web |url=http://thlake.org/_th.php?page=home |title=Twain Harte Lake Association |author= |date=2014 |publisher=Twain Harte Lake Association |access-date= 14 September 2014}} The dam is {{convert|36|ft}} high, {{convert|325|ft}} in length, and {{convert|8|ft}} in width.{{cite web |url=http://www.water.ca.gov/damsafety/docs/Juris%20%28T-Z%292014.pdf |title=Dams Within the Jurisdiction of the State of California (T-Z) |publisher=California Department of Water Resources, Division of Safety of Dams |access-date=14 September 2014}} The dam has a crest elevation of {{convert|3509.8|ft}} and its volume is {{convert|1197|cuyd}}.

In August 2014, fracturing of a granite dome known as "the Rock" located adjacent to the dam forced the closing and draining of the lake for safety reasons.{{cite news |last=Heise |first=Sarah |date=4 August 2014 |title=Twain Harte dam closed after dam springs leak |url=http://www.kcra.com/news/local-news/news-sierra/twain-harte-dam-springs-leak-prompts-flash-flood-warning/27289468 |newspaper=KCRA |access-date=14 September 2014 }}{{cite news |last=Caskey |first=Chris |date=5 August 2014 |title=New cracking at Twain Harte Lake dam worrisome |url=http://www.uniondemocrat.com/News/Local-News/New-cracking-at-Twain-Harte-Lake-dam-worrisome |newspaper=Union Democrat |access-date=14 September 2014 }} It was feared the dam would fail and there would be a flash flood in Sullivan Creek.{{cite news |last=Caskey |first=Chris |date=4 August 2014 |title=Twain Harte Lake Dam leak rattles residents |url=http://www.uniondemocrat.com/News/Local-News/Twain-Harte-Dam-leak-rattles-residents |newspaper=Union Democrat |access-date=14 September 2014 }} The cause of this fracturing is a process known as exfoliation.{{cite web |url=https://arstechnica.com/science/2014/09/a-big-chunk-of-the-sierra-nevada-caught-fracturing-on-video/ |title=A big chunk of the Sierra Nevada caught fracturing on video |last=Johnson |first=Scott K. |date=10 September 2014 |website=Ars Technica |publisher=Condé Nast |access-date=14 September 2014}}

Twain Harte Lake is the name of the reservoir created by Twain Harte Dam. It has a normal water surface of {{convert|12|acre}}, and a maximum capacity of {{convert|143|acre.ft}}. Its drainage area is {{convert|1.04|sqmi}}. The lake is used for recreation and is available only to members of the Twain Harte Lake Association.