The Niigata Prefectural Government said Tuesday it will dispose of radioactive mud that has been stored since the 2011 Fukushima nuclear disaster and ask the operator of the crisis-hit plant to shoulder the costs.

The prefecture, located about 200 kilometers from the Fukushima No. 1 power plant, has stored around 60,000 tons of mud containing radioactive cesium and since 2012 has requested Tokyo Electric Power Company Holdings Inc. to dispose of it.

But the operator has refused, saying it is not able to handle industrial waste. The disposal costs are estimated at ¥3 billion ($27.5 million) and Tepco formally expressed its readiness to pay in December.

The level of radioactive cesium in the mud is below 8,000 becquerels per kilogram, which could be disposed of by regular landfill operations, and most of it is below 100 becquerels per kg, according to the prefecture.

The local government has stored the mud instead of disposing of it, arguing that Tepco should take responsibility for the damage caused by fuel meltdowns at the plant triggered by the massive earthquake and tsunami on March 11, 2011.

The Niigata Prefectural Government has also stored the waste as some local residents were concerned about safety despite the low level of radioactive cesium.

Gov. Hideyo Hanazumi said at a news conference Tuesday it is “not realistic” to keep asking Tepco to dispose of the mud and expressed “regret” that it had taken so long for the operator to decide how to handle the matter.

The contaminated mud, produced at an industrial water supply facility that takes in water from a river containing radioactive materials, is growing by 5,000 tons annually and the storage facility could become full later this year, according to the prefecture.

Jurisdictions other than Niigata have also been grappling with radioactive mud as a result of the crisis at the six-reactor Fukushima complex, with some shouldering the disposal costs.