Dams and protected areas: Quantifying thespatial and temporal extent of global dam construction within protected areas

Protected areas (PAs) are an essential tool for freshwater biodiversity conservation. Given past and expected future global increases in dams and impacts of dams on freshwater ecosystems, we document the number of dams existing or planned within PAs, their history, and the extent of PA downgrading, downsizing, and degazettement (PADDD) proximally caused by dams. Globally, at least 1,249 large dams are located within PAs; two-thirds (907) were built before PA establishment. Additionally, 14% of planned geolocated hydropower dams (509 dams) are located within PAs. PADDD events have also legalized dam construction within existing PAs. Environmental safeguards should preclude development of dams within or adjacent to PAs and prioritize dams within PAs for possible removal and restoration.