Abstract: To systematically assess the nutrient pollution status of the inflow rivers in the Danjiangkou Reservoir Area and its impact on the reservoir water quality, this study analyzed the spatiotemporal characteristics of key nutrient-related water quality indicators—total phosphorus (TP), total nitrogen (TN), and the permanganate index (COD_Mn)—in 16 inflow rivers based on monitoring data from 2021 to 2023, as well as their interannual trends.The results showed that: ① from 2021 to 2023, the river with the poorest water quality was Shending River in the Hanjiang section, followed by Sihe River and Jianghe River.Rivers with better water quality included the Hanjiang River and Duhe River in the Hanjiang section, as well as Taohe River in the Danjiang section.The seasonal variation characteristics of pollutant concentrations in the reservoir′s inflow rivers were complex.For the same river, TP and COD_Mn exhibited similar seasonal patterns, with most rivers showing higher concentrations during the flood season (e.g., Hanjiang River, Duhe River, Taogou River, Danjiang River).In contrast, TN concentrations in most rivers were lower during the flood season (e.g., Shending River, Sihe River, Danjiang River, Laoguan River).② Since the 13th Five-Year Plan period, significant progress has been made in the treatment of heavily polluted tributaries, with TP pollution control achieving better results than TN control.Compared to the 2012~2014 period during the 12th Five-Year Plan, TP concentrations significantly decreased in 12 of the 16 inflow rivers, with reductions exceeding 50% in 8 rivers.The historically most polluted rivers—Shending River, Sihe River, and Jianghe River—experienced TP concentration reductions of 77%, 84%, and 91%, respectively.Only 8 rivers showed reductions in TN and COD_Mn concentrations.Currently, elevated concentrations of nutrients such as nitrogen, phosphorus, and COD_Mn in tributaries like Shending River and Sihe River remained significant risk factors for algal blooms in the backwater areas of these tributaries.TP concentrations in most rivers were higher than those in the main reservoir, while TN concentrations in all rivers were substantially higher than in the reservoir.Appropriate control targets for TP and TN at key monitoring sections of inflow rivers should be established from the perspective of aquatic ecological security in the reservoir area.