This is a famous historical case in Japan that pitted two unequal forces against each other: the Furukawa Corporation and peasant protesters. Prior to the Ashio mining activities before 1880, the surrounding area was densely forested. The destruction of the trees caused by the concentrated sulphurous acid from the mines, caused the erosion of the topsoil, which allowed the rainwater to flow directly into the river. As a result, the Watarase River carried the poisons and affected the agricultural lands nearby. To further worsen the problem, the Ashio mine lacked storage facilities for the slag and untreated ores. Thus, these materials accumulated in the rice-fields through the irrigation systems and caused the topsoil to turn hard like cement. As the copper mining continued, damage to the agricultural lands increased, the farmers were forced to close the irrigation canal gates to keep out the poisons every time it rained. The poisons also affected the quality of drinking waters, which had a serious affect on the people’s health.

In August of 1890the first official serious flooding of the Watarase river basin occurred, damageing 1600 hectares of farmland and 28 villages in Tochigi and Gunma prefectures. This flood initially caused the farmers and villages to get together and create movements against shutting down the mine. However, since1868, the newly established Meiji government’s first national priority was to increase military strength and expand industrial production.

The Ashio Copper mining conflict is significant in Japanese history, because it was the first issue that created a huge surge of environmental movements. Shozo Tanaka is known to have fought for the farmers and the villagers in favour of shutting down the mine. He took direct action for this cause on December of 1901, when he appealed to the Emperor Meiji with a written appeal, whilst constantly shouting for his attention. His actions inspired many people, and in particular high school and university students, who organized movements to spread the information on the grim reality of the situation. He was also involved in organizing one of the greatest mass movements against the copper mining company that took place on the 9th until the 11th of February in 1900 and is known as the “Kawamata incident”.

Shozo Tanaka also took an active role in trying to prevent the Yanaka Village near the Watarase River to be demolished and become a poisoned water catchment basement. He pledged to reside there in order to help the Yanaka villagers fight against the state authorities. However, the project to demolish the village took place in 1910 – 1927.

The activities at the mine continued, and thus Yanaka Village, and the rest of the areas that were gravely affected by the countless disaster were permanently destroyed. The mine closed in 1973, but refineries continued operating using imported ore, until the early 1980s.

Popular environmentalism in Japan was influenced since the 1970s by the memory of the opposition to the Ashio Mine.

Around 1900, between 8000 and 9000 tons of copper were produced per year. In 1890, during the first major flooding, 1600 hectares of farmland and 28 towns and villages in the Tochigi and Gunma prefectures were severely damaged.

In 1893, the conditions on the Ashio Area Mountains that were deforested was approximately 31,360 acres.

In 1899-1890, Shozo Tanaka created a survey of the birth to death ratio in order to show that the copper mine was responsible for murder. 12 villages in the Tochigi and Ibaragi Prefectures were surveyed for the years between 1894 - 1899. The results of the survey showed that the total number of the population is 6,182 in the 5 years whereby the deaths were about 939, and the births were 865. Tanaka also calculated the national average of deaths that took place in 1898 and compared to the areas that were affected by the tragedy, and found out that while the national birth rate was 3.21 and the deaths were 2.60, in the affected areas the births were 2.80, and the deaths were up to 4.12.

Since the copper mining incident affecte a whole different range of areas, people, animals, and crops, it is very difficult to figure out the extent of damage that was done by the mine poisons.