If you're thinking of "levee" as an embankment along a river:
* Ditch - A channel dug to drain water away from an area.
* Channel - A natural or artificial waterway.
* Flood plain - An area of land that is naturally subject to flooding.
If you're thinking of "levee" as a social gathering:
* Solitude - The state of being alone.
* Seclusion - The state of being private and away from other people.
* Reclusiveness - The tendency to live in isolation.
If you're thinking of "levee" as a formal reception or party:
* Informal gathering - A casual social event.
* Intimate gathering - A small, private event.
* Solitary event - An event attended by only one person.
It's important to consider the context in which "levee" is used to determine the most suitable antonym.