The fluid definition of the ‘waters of the United States’: Non-uniform effects of regulation on US wetland protections

Abstract

Recent revisions to the definition of the “waters of the United States” (WOTUS) have considerably altered how wetlands are federally regulated under the Clean Water Act. The two most recent modifications to WOTUS, the Clean Water Rule (CWR) and the Navigable Waters Protection Rule (NWPR), represent two opposing approaches to the federal wetland policy. Despite their implementation, the impacts of these rules on the regulation of wetlands have as of yet been poorly characterized at broad spatial scales. Using New York State (NYS) as a case study, we evaluated the jurisdictional statuses of more than 373,000 wetlands under the CWR and the NWPR to assess the landscape-scale effects of WOTUS re-definitions. We found that statewide and within each of NYS’s hydrologic regions, the NWPR protects fewer wetlands and less total wetland area than the CWR. The efficacy of the two regulations varied considerably in space across NYS, highlighting the need for comprehensive, nationwide assessments of wetland policy outcomes. We also observed that both rules produced non-uniform patterns in jurisdiction across a range of landscape positions and wetland sizes, preferentially protecting large wetlands close to the stream network. This effect was particularly pronounced under the NWPR, which excludes all geographically isolated wetlands from protection. Our findings in NYS emphasize the existence of unique patterns in protected wetlands across spatial scales, highlighting the value in applying geospatial analyses to evaluate environmental policy.

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

“…These federally protected, or federally jurisdictional, waters are defined as "waters of the United States" (WOTUS) by the US Environmental Protection Agency (EPA) and US Army Corps of Engineers (USACE). WOTUS generally includes large "navigable" water bodies and the streams and wetlands connected to them, but the specific definition of WOTUS and what "connected" means has shifted over the past 20 years and has had significant impacts on which waterbodies, streams, and wetlands are protected by the federal government (2,3).…”

“…Given the importance of wetland ecosystems and their myriad beneficial downstream impacts (12), there is a critical need to capture the full range of potential impacts of the Supreme Court's decision. While federal jurisdictional status of waters and wetlands can only be determined by the EPA and USACE, prior studies have demonstrated the utility of estimating federal jurisdictional status based on physical characteristics that align with definitions of WOTUS (3,13,14) This study estimates the federal jurisdictional status of non-tidal wetlands in the conterminous US using a range of potential interpretations of the Supreme Court's Sackett v. EPA majority opinion. The potential interpretations presented here use different wetland flooding frequency thresholds as a proxy for a "continuous surface connection", so wetlands that are "drier" than a given flooding frequency threshold cannot be estimated jurisdictional.…”

A typological framework of non-floodplain wetlands for global collaborative research and sustainable use

“…Based on the specific NFW types, relevant studies have been found across all seven continents, but the studies are predominantly located in North America (between 39% and 96%, for the nine main types; figure 1(b)). This result is presumably due to the origination of 'NFW' terminology, and the further development of legislative/regulatory and management/ funding policies around NFWs in the U.S. (Sullivan et al 2020, Wade et al 2022. Apart from potholes, in which the dominant subtype of prairie potholes is endemic to North America, literature from Asia and Europe have a combined share of pond, marsh, and constructed wetland research, reaching 33%-53%, each close to or higher than that of North America.…”

“…Not surprisingly, other countries, such as U.S., have different and often conflicting policies between federal and state governments-The former has once enforced rules that put NFWs at risk but now more generally promote conservation, whereas the latter have often enacted additional, protective regulations (e.g. Florida in particular) (Creed et al 2017, Sullivan et al 2019, Wade et al 2022. Additionally, laws and regulations that implement indirect protection have been emerging in a few countries over the past two decades.…”