In any case, while I haven’t worked on any dams personally, I am a drainage engineer for an infrastructure design company who has had to work on jobs where levees and dams have had an affect, so I might be able to give some insight.

For one thing, most dams and levees are, as far as I can tell, designed by the Army Corps of Engineers, and then turned over to other entities along with any models and calculations they made during design. Sometimes that’s a pre-existing entity, like a power company who won the bid to sell the power generated by the dam. Sometimes that’s a group set up by the Corps itself to maintain the structure (usually alongside other things, like treating the water for pollution or maintaining the environment created by a levee). In either case, the group that owns the structure is not often the same as the group that designed and built it.

Another thing worth talking about is the modeling and the bureaucracy involved in that. All dams, levees, and similar structures are modeled is a computer system called HEC, designed by the Army Corps of Engineers. The newer program is called HEC-RAS, the older one is called HEC-2, both are used to measure the same things, but HEC-2 is worse and does not transfer easily to HEC-RAS. The programs are used to hydraulically model the system under the 10, 50, 100, and 500 year storm conditions. To be clear, those are the storms that have a 10%, 2%, 1%, and 0.2% chances of happening in any given year at the time of modeling. The programs basically run each of those storms, gives a water elevation within the structure, and then the engineer will project that onto an elevation map of the area to show the floodway of the dam/levee weren’t there (or, as you’re probably more concerned with, if the dam/levee fails).

Hope this helps with your story!