Impact of Regulation on the Water Quality of a Mediterranean River: The Case of the Biobío River

Karla Rodriguez (), Jose Luis Arumi and Verónica Delgado
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Karla Rodriguez: Departamento de Recursos Hídricos, Facultad de Ingeniería Agrícola, Campus Chillán, Universidad de Concepción, Avenida Vicente Méndez 595, Chillán 3800000, Chile
Jose Luis Arumi: Water Research Center for Agriculture and Mining (CRHIAM), ANID Fondap Center, Victoria 1295, Concepción 4070411, Chile
Verónica Delgado: Facultad de Ciencias Jurídicas y Sociales, Campus Concepción, Universidad de Concepción, Edmundo Larenas 219, Concepción 4030000, Chile

Sustainability, 2025, vol. 17, issue 22, 1-17

Abstract: Water quality deterioration is a key challenge for sustainability in river basins under high anthropogenic pressures. This study evaluates the evolution of the Water Quality Index (WQI) in the Biobío River Basin (Chile) between 1994 and 2023 in relation to major environmental regulatory milestones, including Law No. 19,300, Decreto Supremo No. 90, the establishment of the Environmental Superintendency (SMA), and the implementation of the Secondary Environmental Quality Standard (NSCA). A temporal analysis of the WQI was conducted using data from stations along the main river course and its tributaries, complemented by a causal loop conceptual model to explore the interactions between regulation, compliance, and water quality. The results indicate initial improvements in WQI values following regulatory milestones, followed in some cases by stabilization or decline associated with reduced enforcement. Case studies, such as the closure of the Inforsa pulp mill in 2013, illustrate differentiated responses to regulatory change. The conceptual model reveals feedback loops linking enforcement perception and compliance behavior. These findings underscore the importance of sustained implementation and institutional capacity to achieve long-term improvements in water quality.

Keywords: Biobío River Basin; causal loop modeling; environmental regulation; sustainability; water quality; water quality index (WQI) (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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