牛尾海
Another research, recorded and estimated the tidal flushing time of the greater Port Shelter area which their tidal stations were deployed in the Port Shelter proper, as well as in Rocky Harbour, Hebe Haven, Inner Port Shelter and Outer Port Shelter. Such as a station at Leung Shuen Wan (; or known as High Island) and in Po Toi O. They concluded that in the inner Port Shelter, the flushing time is the longest among the fish culture zones of Hong Kong, which is 40 days in the dry season. While Po Toi O is located at the mouth of Port Shelter, its hydrodynamics is mainly affected by the open ocean, thus the flushing time was just 5.3 days in dry season in the computer estimation.