From the record
“The Medina Dam is a hollow-masonry type dam built in 1911 and 1912 by the Medina Irrigation Company in what became Mico, Texas, USA. Medina Lake extends north of it in northeastern Medina County and southeastern Bandera County.”
Wikipedia article Medina Dam, CC BY-SA 4.0.
One of 9 National Register listings published here for Medina County · listed in 1976 · category: Structure.
Sources: the Wikipedia article · the case file at the National Archives · the National Register database, National Park Service