One of the problems with trying to publish a directory of recreational facilities on CoE managed waterways is that availability and usability information changes frequently, either seasonally or in response to weather.
Most of these properties are for flood control, to maintain navigable waterways. Because recreational users are most often there to be near the water, many of the facilities will be closed when a reservoir or section of a river is at flood stage.
We used to have to call the District Office to find out whether a campground was open, now we can usually check it online. But you can't really cover availability by putting dates into a directory, that works only for seasons, not for events.
One of my topo maps, don't remember whether Garmin or DeLorme, has locations of most of the camping facilities in the digital database, but if I am planning to go to a particular campground, I still need to check online, or call, to see if it is open. I've shown up at a reservoir without checking, to find that three of the four campgrounds were temporarily closed by flooding, but was lucky enough to find a vacant unreserved site for the night, because it was mid-week.
For the smaller subset of CoE campgrounds in the recreation.gov reservation systems, if a CG, or even part of a CG, the sites temporarily closed will just show up as not available to reserve (or will look like they are reserved). But that won't tell you whether or not the whole CG is closed, or whether walk-up sites are available, because those are not in the reservations system.