US Patent 7762741 Flow control system for a detention pond

An application for a flow control system includes a movable riser in fluid communication and slideably engaged with a stationary riser, the stationary riser being in fluid communication with a drainage system. The movable riser is made buoyant by one or more attached floats such that, when the liquid level around the flow control system increases to a pre-determined level above a top rim of the movable riser, the movable riser lifts due to the buoyancy of the float(s), thereby maintaining the pre-determined displacement as the water level continues to rise.