Aren’t levees supposed to be dry?
Only if you're in your Chevy.
Areas in and around New Orleans have levees. They constantly hold back water that is normally there. But they are built several feet higher than the water level it holds back. When additional water is received either from upstream sources, or severe weather conditions, like say a hurricane, they can accommodate the increase, unless of course, if they give way like they did during Katrina. 😋