"Three Lines One Permit" environmental policy and its implementation assessment: a case study of Sichuan Province, China

Integrated environmental management is important for sustainable development. Under China's "Three Lines One Permit" (TLOP) policy, three types of management zones—priority protection, critical control, and general control zones—are established based on the ecological red line, the lower-limit line for environmental quality, and the resource use line. Human activities are regulated through a permit system. Integrated and multifactorial protection of soil, plant, hydrological, and atmospheric elements is promoted at the regional level. A follow-up assessment contributes to the improvement of policy implementation and effectiveness. This study demonstrates the achievements of the TLOP policy in Sichuan Province. Results show that (1) 276 protection zones have been established under the ecological red line, covering key ecosystems and protected areas to ensure environmental security. Under the lower-limit line, 1, 626 functional (priority, key, and general control) zones have been designated to regulate air, water, and soil quality, enhancing environmental capacity and pollution control. (2) Through the integration and merging of the three lines, 1, 128 integrated management zones have been established, including 375, 625, and 128 priority protection, critical control, and general control zones, respectively. Each zone has its own list of environmental permits to regulate human activities according to different environmental protection and natural resource development regimes. (3) The design of the follow-up assessment index system was informed by regional primary functions and industrial structure. The index system for provinces and cities is structured around three primary indicators—implementation updating, application, and guarantees—and 15 secondary indicators. The system for critical control zones is structured around environmental access, management, and effectiveness and 14 secondary indicators. A stringent environmental zoning system has been established through the TLOP policy, thereby safeguarding environmental security, promoting harmonious existence between humans and nature, and supporting the vision of Beautiful China.