In March 1990, 58 hectares of reclaimed land that contained more than the regulatory standard (25 ppm of total mercury or higher) was completed at a cost of approximately 48.5 billion yen in a period of 14 long years.

Improvement of the reclaimed land in the around of Minamata Bay is proceeding. A bamboo garden and a multi- purpose square are located on this reclaimed land which is serving as a place of relaxation for the residents. This reclaimed land is slated to be upgraded to be used by everyone, including senior citizens and the this disabled, as a park filled with greenery with a theme of health and environment with Minamata as a place that has sacrificed itself to Minamata disease.

Niigata Prefecture carried out dredging work for the river bottom sediment around the drainage outlets of Showa Denko plant that contained more mercury than the regulatory standard for removal, in 1976. The cost of this work was paid by the company responsible for the cause.

It was ascertained that more than 70-150 tons of mercury were discharged into Minamata Bay by Chisso Co. Ltd. To dispose of this mercuric sludge quickly and safely, the nation, Kumamoto Prefecture, and Chisso, in 1974, shared the expenses of dredging Minamata Bay and reclaiming some of the land.