How wet must a wetland be to have federal protections? Estimating a range of potential impacts from Sackett v. EPA using wetland flooding frequency

In 2023, the Supreme Court's majority opinion in Sackett v. EPA created an unclear requirement that federally protected wetlands must have a "continuous surface connection" to federally protected waters. This study estimates the potential impact of interpretations of the ruling on federal wetlands protections, using wetland flooding frequency as a proxy for the new requirement. An estimated 17 million acres (19%) to nearly all 90 million acres of non-tidal wetlands in the conterminous US could be without federal protections, and variability in state protections creates hotspots of risk. The high-level estimates provided here represent a first step towards understanding the potential extent of the impact of Sackett v. EPA on federal wetlands protections and highlight the uncertainty introduced by the ruling.