The operator of the Fukushima Daiichi nuclear power station says it is pumping groundwater from under the plant to prevent contaminated water from leaking into the adjacent port.
Tokyo Electric Power Company says the heavy rains brought by Typhoon Malakas have raised the underground water levels around the plant's embankments.
TEPCO officials say they added pumps to prevent the groundwater from rising further. They say the water rose nearly to the surface shortly before 10 PM on Tuesday.
The officials say this has prevented rain from permeating the ground and increased the risk that the rainwater could become contaminated and flow into the port.
The utility says that while it is pumping the groundwater to prevent leakage, it will measure the radioactive substances in the water.
Typhoon rain raises tainted Fukushima plant groundwater to surface