The Feds can say yes or no to agreements between States via the Compacts clause 3, Section 10 or Article 1.
Congress when they mandated the Army Corp of Engineers to handle certain river flooding conditions took it upon itself to handle it instead of giving up to a state-limited agreement.
Congress overstepped it’s bounds in doing so. Pure and simple.
Article 1, Section 10, Clause 3 disagrees with you.
It's an explicit right given to Congress.
Better than than teams of people from each State trying to blast the levees in the other State to protect their own.
And things like that did happen on the Mississippi before the Army Corps took over.