JDC Corp., a midsize general contractor, discharged 340 tons of radioactive water into the Iizaki River, which is tapped for irrigation in Minamisoma, Fukushima Prefecture, during government-sponsored decontamination work it was involved in, company sources said Thursday.

Local government officials claimed they were never informed of the action. But JDC sources said the dumping occurred after it received assurances from the Japan Atomic Energy Agency, which contracted it to carry out the decontamination work, that the state body had informed the local governments about the discharge in advance and no problem was anticipated.

The company had not been aware that water from the river would be used for agricultural purposes, the sources added.

A Minamisoma official said the city never received any explanation about the dumping, nor had Fukushima Prefecture, according to a prefectural official.

The Japan Atomic Energy Agency claimed it had verbally notified the city and prefecture, but had not established an agreement in writing.

The Environment Ministry is investigating, suspecting information was not properly conveyed in accordance with law.

The radioactive water was accumulated during agency-sponsored decontamination projects JDC was involved in between December 2011 and February 2012.

JDC engaged in radiation decontamination work in and around Kanabusa elementary school in Minamisoma and accumulated 609 tons of tainted water, according to JDC data made available to Kyodo News.

Of that amount, 269 tons was treated by specialists and the remaining 340 tons was discharged into the Iizaki River, which is used to irrigate rice paddies.

The discharged water included 60 tons with radiation levels at 100 to 121 becquerels per liter, exceeding the agency’s maximum allowable standard of 90 becquerels, the company data indicate. Radioactive substances in the discharged water totaled 16 million becquerels.

The agency approved a JDC plan to transport radiation-contaminated water to a certain collection center in December 2011 and submitted the plan to the Minamisoma Municipal Government.

The city said that at the time, it had expected the tainted water to be taken away.