The Lower Sesan 2 Dam (LS2) is the largest and most controversial hydropower dam ever developed in Cambodia. The 400 MW capacity project, which blocks both the Sesan and Srepok Rivers in Stung Treng Province, northeastern Cambodia, was only completed by a Chinese company, Hydrolancang International Energy Company, in 2018, as part of the Belt and Road Initiative (BRI). Here, I consider the relationship between LS2 and sacred spaces of rural ethnic Lao people, including how spirit mediums and the associated belief systems of local people have been impacted by LS2. Female spirit mediums have contested the LS2 since before its construction began, and have also been directly affected by the dam. Adopting a feminist political approach, the argument is that apart from having potentially important material impacts, dams such as LS2 also serve to alter nature-society relations through variously affecting spirit mediums, their practices, and beliefs associated with spirits.