Public Complaints of Water Pollution: A Long-term Spatiotemporal Analysis in Japan

Public complaints about water pollution are important indicators of public environmental risk perception and provide crucial feedback for evaluating the effectiveness of water resource management strategies. This study conducts a comprehensive analysis of water pollution complaint in Japan from 1989 to 2021, utilizing integrated datasets that include river networks, water quality monitoring stations, regional industrial demographics, and socioeconomic indicators. Our findings reveal a significant decline in complaints—over 45% from the peak in 2006—following the implementation of various environmental policies aimed at reducing industrial discharge and restoring natural ecosystem function. The shift in complaint targets from industries to individuals suggests that these policies have been effective in mitigating industrial pollution, while also highlighting the need to address individual behaviors that impact water quality. Despite long-term improvement in water quality indicators such as Suspended Solids (SS) and Dissolved Oxygen (DO), no significant correlation was observed between these indicators and the temporal or spatial patterns of water pollution complaints. Instead, a strong positive correlation was observed between complaints and reported water quality incidents, reflecting heightened public sensitivity to acute pollution events. Spatial analysis further identified a significant association between complaints and the manufacturing workforce, indicating that industrial activity continues to shape public perception of water pollution risks. Our findings underscore the complex interaction between public perception, environmental policies, and industrial activities, and suggest that effective water management requires a multifaceted approach. Policymakers should continue to enforce stringent industrial regulations, while also enhancing public education and communication strategies to improve awareness of individual responsibilities in water protection. This research provides a theoretical basis for developing more responsive and effective environmental policies and public education strategies.