Atlas of Contaminated Sites

Notable case, Ashio (Nikkō), Tochigi Prefecture, Japan

Ashio Copper Mine

足尾銅山

The mine that supplied 40% of Japan's copper in the late nineteenth century, polluted the Watarase River and stripped the surrounding mountains with smelter fumes. It is regarded as modern Japan's first major industrial pollution case.

Status
Contained
Activity
1877–1989
Media
soil, surface water, sediment, air
Kind of site
mining, smelter
  1. Area. There is no single perimeter. Along the Watarase River, 39.45 hectares of farmland were designated as contaminated by cadmium (1972) and 377.81 hectares by copper (1974), with 2.98 hectares added later (Japanese Wikipedia).

Contaminants

Metals

Metalloids

Status

Contained

Mining ended in 1973 and smelting in 1989. Work on the downstream farmland was completed in 1999. The tailings piles remain in place: after the 2011 earthquake a slump at the Gengorōzawa pile pushed lead in Watarase River water above the standard.

Story

The Ashio mine, known since the seventeenth century, passed in 1877 to Furukawa Ichibei, who turned it into an industrial operation. Sulphur dioxide from the smelter killed the vegetation on the slopes; slag and tailings, rich in copper compounds and sulphuric acid, went into the Watarase. The floods of 1890, 1896 and 1902 spread them over the fields downstream, which became barren; fish died and about 3,000 fishermen lost their living.

The Diet member Tanaka Shōzō led the farmers' protest from 1891 and in 1901 tried to hand a petition to the emperor. The government ordered pollution controls at the mine in 1897 and, between 1902 and 1904, built the Watarase retarding basin, clearing the villages of Yanaka, Kawabe and Toshima.

Pollution went on through the twentieth century. On 30 May 1958 the Gengorōzawa tailings pile failed and the waste reached the river and the paddies of Morita. In 1971 cadmium was found in rice from Morita. On 11 May 1974 Furukawa agreed to pay 1.55 billion yen to 971 farmers. The farmland designated as contaminated was treated between 1981 and 1999 at a cost of 5.33 billion yen, 51% of it borne by Furukawa.

Timeline

  1. 1877Furukawa Ichibei takes over the mine.
  2. 1890First major Watarase flood to carry mine waste onto the fields; others follow in 1896 and 1902.
  3. 1897The government issues the third Mine Pollution Prevention Order.
  4. 1901Tanaka Shōzō attempts to petition Emperor Meiji directly.
  5. 195830 May: the Gengorōzawa tailings pile fails.
  6. 1973The mine closes.
  7. 197411 May: settlement, Furukawa pays 1.55 billion yen to 971 farmers.
  8. 1989Smelting ends.
  9. 1999Work on the contaminated farmland is completed.
  10. 2011After the March earthquake, a slump at Gengorōzawa and lead above the standard in the Watarase.
  11. 2012The Watarase retarding basin becomes a Ramsar wetland.

Remediation

  1. 1902retarding basinWatarase retarding basin (1902–1904) to hold back floods and contaminated sediment, with three villages cleared.
  2. 1947reforestationReplanting of the slopes stripped by smelter fumes: 1.659 billion yen spent by the national forestry service between 1947 and 1975, in addition to prefectural spending.
  3. 1981farmland soil improvementTreatment of the farmland designated as contaminated, 1981–1999, cost 5.33 billion yen.

From the literature

Species that acted on one of this site's contaminants in at least one study. The list is automatic and takes no account of this site's soil, concentrations or climate.

Plants

Fungi

The rest are on the contaminant pages.

Nearby

Notable case, Ōkuma / Futaba, Japan

Fukushima Daiichi and its fallout area

166 km

  • Caesium-137
  • Iodine-131
  • Strontium-90
  • Tritium

Phytoremediation

Notable case, Toyama, Japan

Jinzū River basin (itai-itai disease)

198 km

  • Cadmium
  • Zinc
  • Lead

Sources

  1. Ashio Copper Mine, Wikipedia, 2026
  2. 足尾鉱毒事件 (Ashio mine pollution incident), Wikipedia (ja), 2026

Draft compiled from public sources, not yet reviewed.