Abstract: A system for dewatering tailings is disclosed. The system comprises a thickener having a settling tank; a mixing chamber in communication with the thickener for receiving an effluent from the settling tank, and a flocculating agent tank; wherein a valve is provided for selectively limiting a flow of flocculating agent from the flocculating agent tank to the mixing chamber. An optical detector is provided in optical communication with an effluent from the mixing chamber, and an automation controller is provided in communication with the detector and the valve. In use, the automation controller receives data from the detector and provides a control signal to the valve based on the data from the detector.