> All dams have spillways. That's a broad statement that doesn't apply as generally as you suggest. For example, low-head dams generally don't have spillways t

> All dams have spillways. That's a broad statement that doesn't apply as generally as you suggest. For example, low-head dams generally don't have spillways though in essence function as a spillway. They're entirely passive structures with no mechanism for the owner/operator to change the water impoundment or flow rate.