On December 16 it was reported that
Levels of radioactive materials released outside the plant have declined to 60 million becquerels per hour, one-13 millionth of the levels at the time when the accident occurred. Additional radiation levels at the plant borders have fallen to a maximum of 0.1 millisievert per year, below the government target of 1 millisievert.
Currently, the water in the harbour has a radioactive density averaging at least 150 Bq/L, and every day about 35,000 tons of water enter and leave the port on the tides, carrying about 5 GigaBq of Cs137 and Cs134 with it…. see the data here