I am an old Eng. and we would not build a dam without a spillway. Why do the Levies not have spillways???

Where would you put a spillway on a levee? What would it spill into?

I don't see how this can be done.

A spillway is used to lessen the pressure on a dam by allowing some of the water to flow out of the reservoir. But that water goes into the river below the dam in a controlled manner.

If you let the water "spill" out of the levee , then this is the same as the levee failing. There is no "river below" to spill out the water in a controlled manner.

At the heart of this is the fact that if a levee is being used, the surrounding land is below the water level. The only place for the water to spill is into the surrounding land, which is the problem in the first place.