Structures sometimes get overly simplified:
As if getting them to flow is as easy as opening the gates.
In flat south Florida however, the headwater and tailwater pools don't always cooperate. During times of flood (i.e. following tropical storms, etc.) gates become tailwater controlled. Or in other words, you can open the gates but the other side is already full.
This year it's just the opposite:
The headwater pool is too low: there's no water to flow out.