The United States has always been governed by a president; however, the power to settle disputes between states falls on Congress. This is because of a law in which Congress can make any decision that it deems necessary for the welfare and preservation of the Union.
The argument between Alabama and Georgia over water rights has reached this point:
Who will decide?
For most cases where two states are arguing about decisions within their own borders (e.g., tax rates), one state’s governor may be able to impose his or her opinion upon another without going through Congress, but when those arguments include interstate disagreements, only Congress can stop an argument from escalating further.
For example, when Colorado was considering whether or not they should enter Prohibition with other Western U.S. states, Congress stepped in to establish a national prohibition law against the wishes of Colorado’s governor and people.