How wet must a wetland be to have federal protections in post- US?

In 2023, the US Supreme Court's majority ruled in v. that only wetlands that are "indistinguishable" from federally protected waters "due to a continuous surface connection" are federally protected. This study estimates the potential impact of interpretations of the ruling on federal wetlands protections, using a qualitative measure of wetland "wetness" as a proxy for the new requirement. An estimated area ranging from ~17 million acres (19%) to nearly all 90 million acres of nontidal wetlands in the conterminous United States could be without federal protections, and variability in state protections creates hotspots of risk. The high-level estimates provided here represent a first step toward understanding the long-term impacts of v. on federal wetlands protections and highlight the uncertainty introduced by the ruling.