From the record
“Bagnell Dam impounds the Osage River in the U.S. state of Missouri, creating the Lake of the Ozarks. The dam is located in the city of Lakeside in Miller County, near the Camden-Miller County line.”
Wikipedia article Bagnell Dam, CC BY-SA 4.0.
One of 9 National Register listings published here for Miller County · listed in 2008 · category: Site.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service