*A hypoxic water mass is a body of water with extremely low dissolved oxygen (DO) levels, typically defined as less than 3 milligrams per liter, which threatens aquatic life. It most commonly occurs during summer, driven by a combination of high water temperatures and a significant temperature gap between the surface and bottom layers. 

This year, the accumulated rainfall was the 74 percent level of the average year (as of October 16, 1,530mm), causing hypoxic water masses to form in the depths of around 2-3m which was shallower than 6-7m of average year. The duration in the western part of Jinhae Bay was also 138 days, shorter by 44 days than 182 days of last year.