The Technical Guidelines for Formulating Water Ecological Environment Quality Standards in River Basins can effectively guide and regulate the formulation of water ecological environment quality standards in river basins. It plays an important role in implementing precise, scientific, and lawful pollution control requirements, improving the water ecological environment quality standard system, and maintaining the scientific and authoritative nature of the standards. In order to implement legal requirements such as the Ecological Environment Code, the Yangtze River Protection Law, and the Yellow River Protection Law, support precise, scientific, and lawful pollution control, scientifically guide, regulate, and promote the formulation of watershed water ecological environment quality standards, the Ministry of Ecology and Environment recently released the "Technical Guidelines for the Formulation of Watershed Water Ecological Environment Quality Standards" (HJ 1467-2026) (hereinafter referred to as the "Technical Guidelines"). The demands of different river basins vary. China has a vast territory, and there are significant differences in natural resource endowments, industrial structure layouts, pollution control levels, and water ecological environment conditions among different river basins, resulting in different characteristics and protection needs of water ecological environment in each basin. The Ecological Environment Code specifies that the prevention and control of water pollution should be planned uniformly according to the watershed or region. The Opinions of the General Office of the Communist Party of China Central Committee and the General Office of the State Council on Strengthening Ecological Environment Zoning Control clearly require "focusing on regional and watershed prominent ecological environment issues, implementing precise and scientific policies, and establishing zoning and classification control strategies from problem identification to solutions in accordance with laws and regulations" and "deepening watershed water environment zoning control". Therefore, based on the national water ecological environment quality standards, issuing water ecological environment quality standards for watersheds with prominent water ecological environment problems and specific protection needs is conducive to forming a scientific, systematic, and interconnected water ecological environment quality standard system. Due to the high technical threshold for the development of water ecological environment quality standards in river basins, guidance is needed in the screening of specific pollutants in the basin, determination of project limits, and economic and technical feasibility analysis methods. ”The relevant person in charge of the Water Ecological Environment Department of the Ministry of Ecology and Environment stated that the "Technical Guidelines" can effectively guide and regulate the formulation of water ecological environment quality standards for river basins, and play an important role in implementing precise, scientific, and lawful pollution control requirements, improving the water ecological environment quality standard system, and maintaining the scientific and authoritative nature of standards. As the basic standard for ecological environment, the Technical Guidelines stipulate the basic principles, technical routes, main technical contents, ecological and economic feasibility analysis methods for the formulation of watershed water ecological environment quality standards, as well as the requirements for the text structure and compilation instructions of watershed standards. The basic principles for formulating standards for water ecological environment quality in river basins include compliance with laws and regulations, goal orientation, highlighting characteristics, and scientific feasibility. Specifically, it is necessary to implement the relevant provisions of laws, regulations, and standard management such as the Ecological Environment Code, the Yangtze River Protection Law, and the Yellow River Protection Law. Based on the characteristics and protection needs of the watershed water ecological environment quality, the work of formulating watershed water ecological environment quality standards should be carried out. We should take ensuring the safety of water ecological environment and public health as the fundamental starting point, based on the differences in river basins and existing work foundations, and reasonably determine the positioning and main content of water ecological environment quality standards in river basins. We should fully consider the differential characteristics of the water ecological environment in the watershed, analyze factors such as natural endowment, industrial structure, and economic and technological level, and propose specific control projects and control objectives that meet the characteristics and protection needs of the watershed. On the basis of clarifying the types of water ecological environment quality standards in the watershed, based on research results such as ecological environment benchmarks and risk assessments, combined with ecological environment benefit analysis and technical and economic feasibility demonstration, the control requirements of the watershed water ecological environment quality standards should be reasonably determined to improve the scientificity and feasibility of the standards. What technical work should be carried out for the formulation of watershed water ecological environment quality standards, and how to screen specific control projects in the watershed and determine limit values? The above-mentioned person in charge introduced that the main technical work includes: analyzing the problems in the implementation of national water ecological environment quality standards and the needs for water ecological environment protection in the basin, conducting research and analysis on the characteristics of water ecological environment in the basin, clarifying the types of water ecological environment quality standards in the basin, determining the main technical content of the standards, analyzing the ecological environment benefits and technical and economic feasibility of standard implementation, writing standard texts and preparation instructions, etc. The determination of specific control projects for a watershed is mainly based on the type of watershed water ecological environment quality standards, combined with the research and analysis results of watershed water ecological environment characteristics, and taking into account the actual situation for overall setting. Meanwhile, based on the urgency of improving the water ecological environment quality in the watershed, specific control projects can be divided into mandatory basic control projects and selective control projects for tracking and investigation. In terms of limit determination, it is mainly based on the latest research results of water ecological environment standards and risk assessment, combined with economic and technological level and management feasibility. For projects other than the basic items of the national water ecological environment quality standards, unified limit values for protecting human health or aquatic organisms should be formulated, and graded limit values should not be formulated for different water body functional classifications. For aquatic organisms, priority should be given to using the evaluation grading reference values provided in the published relevant standards. When the evaluation needs cannot be met, the evaluation grading standards should be determined based on the survey and monitoring data in the watershed and statistical methods. The "Technical Guidelines" are applicable to guide and regulate the revision of surface water ecological environment quality standards for specific river basins carried out by the State Council's ecological environment department or provincial people's governments. The above-mentioned person in charge pointed out that there are five types of situations where the water ecological environment quality standards for river basins are applicable. Specifically, when specific species or special ecological protection areas within a watershed have higher protection needs, strict limit type watershed water ecological environment quality standards can be formulated, which are stricter than the national standard limits. For watershed characteristic pollutants such as heavy metals such as total antimony and total thallium, toxic organic or inorganic pollutants, etc., if the state only stipulates standard limits applicable to the protection of human health in centralized drinking water source areas, supplementary and improved standards can be formulated to specify standard limits applicable to the protection of aquatic organisms in non drinking water source areas. For toxic and harmful water pollutants (including new pollutants) that are not regulated by the state but have a high detection rate in the watershed and need to be controlled, supplementary and improved standards can be formulated to ensure public health and ecological environment safety, and corresponding standard limits can be set. For watersheds with important water ecological environment functions or prominent water ecological problems, supplementary and improved standards can be formulated to specify evaluation items and methods for aquatic organism integrity. If there is a need for both strict limit values and supplementary improvement in a watershed, a composite standard can be formulated to supplement new control items and requirements while tightening the control requirements for projects already specified by the state. It is reported that the "Technical Guidelines" will guide various regions to take ensuring the safety of water ecological environment and public health as the starting point, and formulate characteristic control projects and control objectives that are in line with the characteristics of water ecological environment, environmental protection needs, and actual economic and social development in different river basins, in order to achieve effective connection and complementarity with national standards, which is conducive to improving the water ecological environment quality standard system and providing basic support for further enhancing the level of water ecological environment protection in China. (Looking into the New Era)