A win, win, win, solution:

1. Dig a moat the length of the Mexican border.

2. Take the dirt from diggin the moat, raise the levies in New Orleans

3. Put the Florida alligators in the moat.

Immigration problem along border with Mexico - solved
Flooding problem in New Orleans - solved
Alligator attacks in Florida- solved

Are there any other problems you would like for me to solve?