Who has jurisdiction on Lake Eufala that is between Alabama and Georgia?

The dam puts some aspects of it under federal control. However the water coming into Eufala comes from both Georgia and Alabama and at present there is a massive law suit involving Florida, Georgia and Alabama on how much water each state gets. I live close to Lake Lanier, which is upstream on the Chattahoochie River and they are constantly letting water out of that to keep the lakes down stream at reasonable levels.

Lake Texoma in Texas/Oklahoma was also built by the corp or engineers but the legal responsibilities on the lake are by the states. For instance if you only have a Texas fishing license in your pocket you better be sure you are in Texas waters. I can't answer the gun question but if the two states don't recognize each other's concealed carry laws then that is the problem. Most dams are built by the federal government the lakes belong to the states but concessions and so on are licensed by the corp or engineers. Your gun permit may also come under federal laws on the lake.