Tokyo Electric Power Company, or TEPCO, said the water which spilled from the storage tanks had radiation readings as high as 200,000 becquerels per liter — almost 6,700 times higher than the legal limit of 30 becquerels.

Although sandbags have been placed to prevent further spread of the leak, some of that water may have already reached the plant’s harbor on the Pacific Ocean through a drainage trench, TEPCO said.

The leak comes one day after Japanese fast food company Yoshinoya Holdings announced plans to grow vegetables on a farm just 60 miles from the nuclear plant.

A TEPCO spokesman told a press conference in Tokyo on Thursday that the leak happened because workers miscalculated the amount of water the tank was capable of holding due to it sitting on a slope.