Environmental protection and management require a clear division of authority between the central and local governments to ensure effective governance, legal certainty, and the implementation of sustainable development. Changes in environmental regulations have created a need for harmonization to prevent overlapping authorities, unclear responsibilities, and differences in policy implementation at both the central and local levels. This study aims to analyze the regulation and harmonization of local government authority in environmental protection and management. This study employs a normative legal research method using statutory and conceptual approaches. Legal materials were analyzed qualitatively to identify the consistency of authority arrangements between the central and local governments. The results show that local government authority has a legal basis regulating its roles and responsibilities; however, regulatory developments require synchronization and clarification of the boundaries of authority to ensure that its implementation remains clear, consistent, and effective. Harmonization is necessary through regulatory alignment and strengthened intergovernmental coordination. The implication is that the harmonization of authority can strengthen legal certainty, support the implementation of regional autonomy, and promote sustainable environmental protection and management.