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.