Fukushima Prefecture’s Arakawa River has been deemed to be the cleanest river in Japan by the federal Ministry of Land, Infrastructure, Transport, and Tourism.
The ministry awarded the designation despite not announcing any tests for radioactivity in water, sediment, plants, or fish.
The Arakawa River (not to be confused with another river of the same name that empties into Tokyo Bay to the south) flows about 30 kilometres from Mt. Azuma east to Fukushima city, where it joins the Abukuma River.
River close to crippled nuclear plant
Fukushima city is located about 70 kilometres west of the devastated Fukushima Daiichi nuclear power plant, which suffered triple core meltdowns after the earthquake and tsunami that struck eastern Japan in March 2011 and killed about 19,000 people.
The crippled facility spewed highly radioactive material into the atmosphere and has been releasing large amounts of radioactive groundwater into the Pacific Ocean on a daily basis since then.
Fukushima city is close to the exclusion zone established around the Daiichi plant after the disaster, when officials evacuated 300,000 people from the area. About 120,000 people remain unable to return to their homes and farms more than three years later.
PM pushing for nuke plants to reopen
The federal announcement comes as Prime Minister Shinzo Abe’s Liberal Democratic administration is pushing to bring Japan’s approximately four dozen nuclear power plants back online. The complexes were shut down after the quake- and tsunami-spawned catastrophe and must apply to Japan’s new nuclear-watchdog agency to restart.
Nineteen reactors in 12 plants are in the process of having safety plans reviewed by the Nuclear Regulation Authority (NRA), with two reactors at the Sendai complex in Kagoshima Prefecture expected to be the first back in business, probably by this fall.
Before 2011, nuclear power supplied about 30 percent of Japan's power. To make up the shortfall, the country has had to rely on increased, and expensive, imports of natural gas and thermal coal.
Surveys have shown that as many as three-quarters of the Japanese populace favour shutting down the nuclear industry in their country.
No radioactivity tests announced
Prior to 2011, the Arakawa River claimed top spot for water quality from 2004 to 2007 in northeastern Honshu’s Tohoku region, which consists of six prefectures, including Fukushima. Also in 2007, it tied with six other rivers in Japan for cleanest water in the country.
This latest honour, proclaimed on July 22 and reported by the Fukushima Diary website, came after analysis of the results of biochemical oxygen-demand tests conducted by the ministry in 2013.
No tests for radioactivity were announced as having been conducted.
Study shows monkeys affected
The federal and various prefectural governments are involved in ongoing Tohoku revitalization programs and public-relations exercises aimed at restoring national and international confidence in the area and its agricultural, fishing, and tourism potential.
Major decontamination and soil-remediation projects, mostly involving bagging material and storing it in designated areas, have been ongoing in four Tohoku prefectures for more than two years.
The river award came just two days before the publication in Scientific Reports of a yearlong study of wild Japanese monkeys (Macaca fuscata) in the Arakawa area that showed “significantly low” white and red blood cell counts and high muscle-cesium concentrations in the animals when compared to a population of monkeys in northern Honshu’s Shimokita Peninsula, 400 kilometres north of Daiichi.
A future study aims to determine the levels of strontium-90 in the monkey population.
River runs through contaminated area
The report stated that after the 2011 nuclear-plant core meltdowns, federal-government studies showed that radiocesium contamination of soil in and around Fukushima city (essentially the entire length of the Arakawa River) measured between 10,000 and 300,000 becquerels per square metre.
According to NRA figures used in the study, the cumulative atmospheric radiation dose in the area outside the exclusion zone during the two years immediately following the disaster was 7.5 mSv (millisieverts).
As reported in the Asahi Shimbun newspaper on July 5, 2012, a Japanese Environment Ministry study in December 2011 and January 2012 found higher cesium concentrations in fish and insects in Fukushima Prefecture lakes and rivers than in local sea life.
Fish in lakes found to be radioactive
Since April 2012, the paper reported, cesium levels in fish and shellfish in three Fukushima lakes were found to be above the federal limit of 100 becquerels per kilogram for food.
Contaminated sand, mud, and organic material get washed into rivers and streams from surrounding countryside through erosion, flooding, and rainfall, eventually making its way downstream or concentrating in sediments.