In a recent ruling, the Matsuyama District Court dismissed a lawsuit filed by victims of flooding caused by the emergency release from the Nomura and Kanogawa dams during the 2018 West Japan Heavy Rain. The plaintiffs, including victims' families and residents affected by the floods, sought approximately 540 million yen in damages from the national government and local municipalities, claiming that the emergency releases were to blame for the widespread flooding that affected around 3,500 homes and resulted in eight fatalities. The court ruled in favor of the government, stating that there was no negligence in the operation protocols of the dams.

The main argument presented by the plaintiffs was that the operational rules governing the dams were inadequate and failed to account for extreme flooding events, thereby leading to the necessity of the emergency releases. They argued that had the dams operated similarly to other facilities in Japan, which adjust outflow rates according to inflow volumes, the emergency release could have been avoided entirely, preventing the devastating impacts it had on the downstream communities. Additionally, they contended that the response to the heavy rains should have been more adaptable, suggesting that the dams should have increased outflow before the emergency was declared.

Contrarily, the government defended its dam operations, asserting that the existing rules were established through a thorough analysis of historical flood occurrences and environmental conditions. They claimed that their actions were reasonable and conducted within legal frameworks without any negligence. Another point of contention was the adequacy of communication regarding the emergency releases, with plaintiffs alleging that the information disseminated to the public was insufficient. However, representatives for the government maintained that they had appropriately shared information about the emergency procedures and responsibilities, denying any wrongdoing.