Basically the dam is owned, and operated by the Army CoE, the civilian branch of the military. Because of a referance to a very obscure CFR, firearms are prohibited on, or about, CoE property. Now, the land surrounding th elake, and the Licking river, is a majority of National Forest apart of the DBNF, with some private land and farms thrown in here and there. I've Open Carried every single time I've been to Cave Run, but I do so when not on or near the dam, or the spill-way. And from what I've heard from a DBNF LEO, you cannot have a firearm on or in a water vehicle when on the lake itself. But, point being, just stay away from the spill way, and either side of the dam itself, and you're fine. You can still OC at the Fish Hatchery, and the hatchery's access to the Licking river (plenty of crappie to be caught there), and around and near the lake at other parts.
I don't know about any court rulings dismissing the CoE's weapons ban on its property, but unless you see proof that such a case existed, and that it applies under the full-faith and credits clause, to be legal in Kentucky, then just stay away from the dam.
Hey, if you're looking for some good fishing spots, I'd be happy to show you some places, I mostly do night fishing, but when I get my boat operational, I'd be happy to take a fellow OC'er for some hard-to-reach fishing places.