The windowlike arches on the outside of the towering Mountain Dell Dam provide an artistic facade that fits with the natural beauty of the Utah mountain canyon where the century-old structure sits.
The design's historical significance earned it a spot on the National Register of Historic Places and a designation as an American Water Works Association Landmark.
But the concrete structure also sits on a less desirable list: It is one of five dams in Utah and at least 1,688 in the United States that are in poor or unsatisfactory condition and located in places where a breach would likely kill at least one person, according to an investigation by The Associated Press.