A system and method reducing pollution in a body of water using biological processes is provided. The system includes a hydraulic dam generated by an induced downwelling of effluent water from a plurality of water circulating devices. A series of linearly arranged treatment sub-systems are disposed upstream of the hydraulic dam. The treatment sub-systems include a water sterilization sub-system for neutralizing harmful and undesirable micro-organisms using an ultrasonic energy generating unit. The ultrasonic energy generated, is of a frequency that disrupts cellular structures in targeted micro-organisms.