The success of marine pollution prevention relies on several managerial tools and knowledge
from the interdisciplinary sciences. As the critical source of pollution, seaports need a variety of policies
and practices for enhancing their environmental performance. This paper contributes the existing
literature and the implementation by analyzing the season of operational waste from maritime
transportation. The seasonal regression analysis (SRA) was performed by using the data from Port
Authority of Thailand. The adjusted model provides a greater statistics for identifying the seasons than
that of the original model which was impaired by the obsolete information. To ensure the correctness of
the finding, the result of SRA was compared with the seasonal index, goodness-of-fit measure and model
error obtained from times series analysis. The conclusion was mutually agreed by two approaches
indicating the reliability of the research finding. As the vacillation of operational waste depends on time,
port authority should pay a close attention during the high season. Thanks to the enormous amount of
operational waste, the monitoring of ship and marine environment should be strictly implemented.
However, the pollution-related concern can be alleviated during the interval of the low season due to the
scarce demand for discharging operational waste at the port.