A method for controlling bivalve growth in a service water system of a plant is disclosed. Upon detecting an increase in the number of veligers or settlement stage bivalves, chlorine anion is introduced into the service water to obtain a chlorine anion concentration of between 0.10 and 2.0 mg/l for a period of 10 to 40 days. Also disclosed is a two-stage method for controlling bivalve growth in a service water system.
