“清泉洞”穿越坝体，是大坝工程隐患，搞清楚“清泉洞”的补给水源是库水补给，还是原地下水补给，是除险加固方案成败的关键。通过工程地质勘察和稳定同位素研究认为，“清泉洞”水是库水经过左岸玄武岩裂隙、淤积层及坝体渗透补给，采取针对性的措施，实践证明效果显著。 “Qingquan hole” crossing the dam body is a hidden danger of the dam project. It is crucial for the success or failure of the reinforcement project to find out whether the recharge source of “Qingquan Cave” is the reservoir water supply or the original groundwater recharge. According to the engineering geological survey and stable isotope study, “Qingquan Cave” water is a reservoir water that has been infiltrated by basalt fractures, silt layers and dam bodies on the left bank. Targeted measures have been taken and proved to be very effective.