International nuclear regulators warned this week that the growing amount of radioactive water at Japan’s crippled Fukushima Daiichi nuclear plant remains a threat.

In its report, the International Atomic Energy Agency again urged the plant’s operator to treat the water to remove most of the radiation, then dump it in the sea.

“The IAEA team is of the opinion that the present plan to store the treated contaminated water containing tritium in above ground tanks, with a capacity of 800,000 cubic meters, is at best a temporary measure,” the group wrote.

A large amount of radioactive water was released following the earthquake and tsunami nearly four years ago that destroyed the plant.

Since then, about 160 million gallons of contaminated water has accumulated in storage tanks on the site. About half has been treated to remove most radioactive contaminants.

Across the Pacific, Oregon’s Public Health Division remains the only state or federal agency monitoring sea water for Fukushima radiation.

Oregon tests sea water quarterly at three coastal locations – Oswald West State Park on the north coast; Heceta Beach on the central coast, and Harris Beach on the south coast.

Its latest samples, taken in November and published this week, show no activity above normal background levels.

Oregon is testing for cesium 137 and iodine 131. An increase in either would show something is afoot, but wouldn’t prove the radiation came from Fukushima.

Ken Buesseler, a scientist at the Woods Hole Oceanographic Institute, last year began a crowd-funded citizen science project to also test for cesium 134, the so-called Fukushima fingerprint.

In November, Buesseler released test results showing that very low levels of Fukushima radiation had been detected about 100 miles off the coast of Eureka, California and 400 miles off the coast of Newport, Oregon.

At those low levels, the radiation is not expected to harm humans or the environment.

The IAEA inspection team also noted that some progress has been made in the massive decommissioning effort at the power plant.

Several important tasks have been completed since 2013, the report notes, including “completion of the removal of fuel from Unit 4; the improvement and expansion of contaminated water treatment systems; the installation of new tanks and associated systems for contaminated water storage; the operation of underground water bypass; and the clean-up of the site resulting in the enhanced working radiological environment.”