Abstract: The aim of this research is to further investigate the effectiveness of comprehensive governance and policy implementation for the Tuojiang River. According to monitorings at sixteen state-control sections and one background reference point in February from 2016 to 2019 , the water quality of Tuojiang River Basin in Winter and Spring Alternate (WSA) was compared and analyzed by using WQI_min method. Seven parameters including pH value, dissolved oxygen (DO), total phosphorus (TP), total nitrogen (TN), ammonia nitrogen (NH₃-N), permanganate index (COD_Mn) and electrical conductivity (EC) were selected for comparative analysis. The contribution rate of each parameter was also examined by using comprehensive water quality index method. Results revealed an ever-increasing water quality in the WSA from 2016 to 2019 in Tuojiang River Basin: sections of extremely inferior water quality were eliminated in 2019; total phosphorus pollution has been effectively controlled in the upstream. Nevertheless, total nitrogen pollution was prominent across the whole basin, and water pollution in the background sections has emerged. Controlling domestic sewage and agricultural non-point source pollution should be the focus of treatment of Tuojiang River Basin, especially the downstream.

Key words: water quality, assessment, difference analysis, Tuojiang River Basin, winter and spring alternate