In November 2006, fishermen from Nagasaki, Saga, Fukuoka and Kumamoto prefectures around Ariake Sea filed a lawsuit, demanding removal of the dike in Isahaya Bay in Nagasaki Prefecture or at least the opening of the dike's gates. They said dike construction had caused their fish catch to dwindle.
The dike was constructed far inside the bay, whose mouth opens to Ariake Sea. The dike's gates were closed in 1997 to reclaim land for agriculture and create a freshwater pond. The land reclamation project was completed in November 2007. At a cost of ¥253.3 billion, it created 672 hectares of agricultural land and a fresh water pond of 2,600 hectares.
In June 2008, the Saga District Court ruled in favor of the plaintiffs, ordering the government to open the gates north and south of the 7-km-long dike for five years.