Officials are overseeing the cleanup of a spill of 400,000 gallons (1.5 million liters) of radioactive water from a nearby nuclear power plant in Minnesota.

Xcel Energy, the power company that operates the nuclear plant, has stated that the radioactive water leak “was fully contained on-site and has not been detected beyond the facility”.

State officials reassured that there was no imminent threat to public health. However, it was revealed that the spill had been identified in late November, but the authorities did not inform the public until Thursday.

The water is contaminated with tritium, a usual byproduct of nuclear plant activities, the BBC reported.

On November 21, Xcel Energy detected a leak from a pipe between two buildings at its Monticello plant, located approximately 35 miles (56 km) upstream along the Mississippi River from Minneapolis, the state’s most populous city.

The utility company stated that it had informed both the state and the NRC of the leak on the following day after it was discovered.

Officials from the state explained that they had held off on making the leak public until they had more details, but assured the public that the radioactive water was still contained on Xcel’s premises and did not present an immediate threat to public health.

Written by staff