USACE Written Permission
As far as I can tell, in order to carry weapons on any lake or project covered under US Army Corp of Engineers needs special permission from the District Commander (National Parks are under different laws).
Anyway, I called my local district a few years back and they got me to the right person and had me email them a document with a plain request. In turn, they mailed me permission with a few stipulations: Concealed carry only. No carry in buildings. Must maintain CCW/LTC. Only applies to the listed lakes/projects in the letter. May be revokes if XYZ. Etc.
Recently, I started emailing all districts I may visit, and so far they are replying, asking for a DL and CCW, and issuing a similar letter (1 sent it via email, the rest I am waiting to hear back).
Anyway, I wanted to share this experience and info since there are a number of USACE public lakes where you are federally prevented from carrying weapons (even in your car) just because USACE is involved. You may not even realize this is the case.
You too can email them a request with your info and they should give you permission as well.