In 1610, a massive copper vein was discovered in Ashio, a village in Tochigi Prefecture, 150 km north of Tokyo, Japan. As the Ashio mine grew, so did the waste from mining and refining, all of which was dumped into the nearby Watarase River.  From early 1878, signs of copper pollution began to appear in the river. The water was contaminated with copper, causing numerous fish to die off, and people who bathed in the river began to develop skin problems. This was the first recorded environmental disaster in Japan and the prelude to many environmental disasters which followed, such as Minamata, Itai-itai, Niigata, Yokkaichi, Kanemi oil, and other disasters.