Highly contaminated water is leaking from a damaged reactor at the Fukushima Daiichi nuclear power plant, Japan’s nuclear regulatory agency reports. The water, registering radiation levels of 1,000 millisieverts per hour, or four times the maximum allowable annual dose for workers at the plant, was found in an overflow tunnel outside Reactor No. 2. In a news conference, a representative of the Nuclear and Industrial Safety Agency said the water may already have overflowed the tunnel, which opens about 180 feet from the sea. But the nuclear agency says even if the water flows to the sea, it won’t pose a health risk because fishing has been banned from the area. It’s still not clear where the water is coming from: Officials say it’s leaking from either broken pipes inside the reactor, a breach in the containment vessel, or from an inner vessel that houses the fuel. Workers are pumping less cooling water into the reactors in order to minimize the leak. The nuclear regulatory agency has also detected plutonium—a radioactive metal—in the soil at five separate locations at the power plant. They insist its concentration level is harmless to humans, but have promised to increase monitoring of the plant's environment.