The spatial distribution and formation mechanisms of high-fluoride (F⁻) river water influenced by hot springs and damming remain inadequately understood. Hence, 50 water samples, including 7 hot spring samples, 11 groundwater samples, 4 surface runoff water samples, and 28 river water samples, were collected to analyze the spatial distribution, hydrogeochemical behaviors, and formation mechanisms related to elevated F⁻ levels in river water around hot springs and damming using geochemical factor analysis and classical statistical tools. In this study, F⁻ concentrations in river water were inversely proportional to the water flow distance and exceeded 1.00 mg/L when flowing through the Clear Water Bay hot spring. The high-F⁻ river water initially originated from the dissolution of hot spring historical sediments containing large amounts of bearing-F- minerals. Moreover, Na+ on the surrounding sediments exchanged with Ca2+, and a stronger competitive effect between more HCO3 ⁻ generated through river damming with F⁻ facilitated greater release of F⁻ desorption from sediments. This research will aid in improving the understanding of the geochemical behavior of F⁻ under hot springs development and provide useful insights into the environmental safety of river water within the study area.