The purpose of this study was conducting a risk assessment of the environment due to the implementation of ballast water management on vessel operations. Environmental risk assessment was based on the pertaining laws and regulations of the government of Indonesia Republic and international laws, as well as the sample comprising vessels operating in Indonesian waters. The data used for the analysis were based on the visits of the vessels operating in the operation territory of Inaport I - Inaport IV. The analysis was carried out based on the number of vessels that unload the ballast water at the port and IMO regulation MEPC 56/23 ANNEX 2. The amount of ballast water unloaded measurement used statistical method to determine the probability of risk occurrence. Using a risk matrix, the ranking of environmental risk due to the implementation of ballast water management would be achieved. In 2016, the numbers of ship visited in International route were 30.843 ships and the assumption was the ships conducted deballasting was 60% from the ship numbers in each time throwing ballast water around 25 tons, so, the total water discharged was 450.000 tons.