<p>Heavy metal contamination (HMC) in sediments from dam reservoirs along mining impacted rivers is a particular important issue for environmental protection and aquatic safety for watersheds. This study took a geochemical analysis on major and trace elements in sediments from the dam reservoir at Changsha city along the mining-impacted Xiangjiang River in Hunan province (China). The results indicated that compositions of major and some trace metals in dam sediments (DS) were similar to those in pre-dam fluvial sediments (FS). Specifically, variations were noted in the distribution of heavy metals Ni, Mn, Zn, Cd, Cu, and Pb, with DS showing significantly higher Ni concentrations (up to 7699.5&#xa0;mg/kg) and lower levels of Mn, Zn, Cd, Cu, and Pb. Compared to FS, the contamination degree of heavy metals Mn, Zn, Cd, Cu, and Pb in DS had decreased, while the Ni contamination in DS was particularly severe. The contamination of Ni as well as Cd in DS can lead to high levels of ecological risk. Specifically, the non-carcinogenic risks of Ni and Cd for adults and children were predominantly observed in some certain dam reservoir sediments. Source identification indicated Mn, Zn, Cd, Cu, and Pb in DS might originate from mining activities, whereas Ni was primarily derived from waste discharges, such as shipping port coating and catering activities within the reservoir. Therefore, it is crucial to closely monitor and control anthropogenic activities, both upstream and within the dam reservoir, to protect against metal contamination, particularly for Ni and Cd.</p>