I like the idea of being able to cut off the sediment pond supply during down pours to keep muddy water out. I suppose if you knew when the downpours were coming you could close a valve or put a plug at the inlet. I was also thinking one could probably design a shut off flapper that would close automatically by use of a float. When the float rose above a certain level the flap would rotate about a hinge to shut off flow. Maybe something like a toilet tank float. Not sure about how to make it open back up automatically since the water level would only drop to the spillway height.
