Clarify jurisdiction of US Clean Water Act

Ward, Adam S.; Wade, Jeffrey; Kelleher, Christa; Schewe, Rebecca L.

doi:10.1126/science.adf7391

Cited by 4 publications

(5 citation statements)

References 2 publications

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“…Likewise, slow subsurface hydrologic connectivity extends residence times that enabled further biogeochemical processing (Marton et al., 2015) including landscape nutrient retention (Cheng & Basu, 2017; Cheng et al., 2022). In short, the heterogeneity in connectivity within and between wetlandscapes documented here impacts a multitude of functions considered under the Clean Water Act (Creed et al., 2017; Lane et al., 2018; Sullivan et al., 2020; Wade et al., 2022; Ward et al., 2023). Given the evidence for both surface and shallow subsurface wetland connectivity, the collective impacts of wetlands across coastal plain wetlandscapes on the physical, chemical, and biological functions of downstream waters seems clear.…”

Section: Discussionmentioning

confidence: 89%

“…For example, variability of wetland surface connectivity is a factor influencing chloride accumulation (Thorslund et al., 2018), and a strong regulator of landscape nutrient retention (Cheng & Basu, 2017; Cheng et al., 2022). However, because surface connectivity between depressional wetlands and adjacent water bodies is not persistent, these “geographically isolated wetlands” have been assumed to lack meaningful contributions to the hydrological and biogeochemical functions of downstream “waters of the United States”, with crucial implications for shifting U.S. Federal protections under the Clean Water Act (Creed et al., 2017; Sullivan et al., 2020; Wade et al., 2022; Ward et al., 2023). While the presence or duration of surface connectivity is not, nor should not be, the sole criterion for defining a “significant nexus,” it is clear that understanding the spatial and temporal patterns of wetland connectivity along both surface and subsurface flowpaths is relevant across scientific and regulatory discussions (Leibowitz et al., 2008).…”

Section: Introductionmentioning

confidence: 99%

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Patterns of Wetland Hydrologic Connectivity Across Coastal‐Plain Wetlandscapes

Lee

Epstein

Cohen

2023

Water Resources Research

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Depressional wetlands influence the functions of wetlandscapes by storing and releasing water, providing critical habitat, amplifying carbon and nutrient cycling, and influencing microclimate. Despite persistent subsurface connectivity, depressional wetlands are surrounded by uplands so only sporadically connect via surface pathways. However, the frequency, duration, and relative importance of surface connectivity in depressional wetlands remains poorly understood, limiting quantification of their landscape functions. Using multiple years of stage variation in 67 depressional wetlands across four contrasting wetlandscapes, we observed wetland spill elevation is exceeded 10%–40% of the time, with substantial variation within and between wetlandscapes. Moreover, surface connectivity increased water loss rates by 200%–350% on a depth basis and 350%–850% on a volumetric basis compared with subsurface water loss rates. This temporally disproportionate water export suggests that short‐lived surface connectivity is crucial for aggregate landscape export of water‐borne materials and numerous hydrologic and habitat services. Contrasting water loss rates above and below spill thresholds create homeostatic feedback that stabilizes water levels near the thresholds. We explored geomorphic, climatic, and vegetative influences on hydrologic connectivity, quantified as nighttime recession rates below the spill threshold for groundwater connectivity and percent time above thresholds for surface connectivity. Groundwater connectivity was consistently greater in deeper wetlands and wetlandscape identity was the primary factor explaining variation in surface and subsurface connectivity. Our results highlight the critical role of surface connectivity in coastal plain wetlands, illustrate the heterogeneity of those wetland functions within and across wetlandscapes, and provide hydrologic benchmarks for evaluating restoration of aggregate landscape functions.

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Section: Discussionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Patterns of Wetland Hydrologic Connectivity Across Coastal‐Plain Wetlandscapes

Lee

Epstein

Cohen

2023

Water Resources Research

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“…As many others in the scientific community have said before (11,26), lawmakers should act and implement robust federal wetlands protections that are based on sound science. States without wetlands protections should implement robust permitting programs, and all states with state-level protections should fully fund their agencies that enforce their regulatory protections.…”

Section: Discussionmentioning

confidence: 98%

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

Gold

2024

Preprint

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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.

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“…In the US, federal policy debates over non‐perennial stream protections focus on “significant connectivity” between non‐perennial streams and downstream “navigable” waters (Alexander, 2015). Since 2015, three different Environmental Protection Agency rules have been used to define protections of non‐perennial streams—resulting in repeated disagreement and reversal of protections (Ward et al., 2023). Definitions of protected waters have considered if they have a “significant nexus” (Clean Water Rule, 2015), if they are “relatively permanent” (Navigable Waters Protection Rule, 2020), or more recently with new US federal protections that allowed either the “relatively permanent standard” or “significant nexus standard” to classify protected waters (Revised Definition of “Waters of the United States,” 2023).…”

Section: Introductionmentioning

confidence: 99%

Changes in Water Age During Dry‐Down of a Non‐Perennial Stream

Swenson,

Zipper,

Peterson

et al. 2024

Water Resources Research

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Non‐perennial streams, which lack year‐round flow, are widespread globally. Identifying the sources of water that sustain flow in non‐perennial streams is necessary to understand their potential impacts on downstream water resources, and guide water policy and management. Here, we used water isotopes (δ18O and δ2H) and two different modeling approaches to investigate the spatiotemporal dynamics of young water fractions (Fyw) in a non‐perennial stream network at Konza Prairie (KS, USA) during the 2021 summer dry‐down season, as well as over several years with varying hydrometeorological conditions. Using a Bayesian model, we found a substantial amount of young water (Fyw: 39.1–62.6%) sustained flows in the headwaters and at the catchment outlet during the 2021 water year, while 2015–2022 young water contributions estimated using sinusoidal models indicated smaller Fyw amounts (15.3% ± 5.7). Both modeling approaches indicate young water releases are highly sensitive to hydrological conditions, with stream water shifting to older sources as the network dries. The shift in water age suggests a shift away from rapid fracture flow toward slower matrix flow that creates a sustained but localized surface water presence during late summer and is reflected in the annual dynamics of water age at the catchment outlet. The substantial proportion of young water highlights the vulnerability of non‐perennial streams to short‐term hydroclimatic change, while the late summer shift to older water reveals a sensitivity to longer‐term changes in groundwater dynamics. Combined, this suggests that local changes may propagate through non‐perennial stream networks to influence downstream water availability and quality.

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Clarify jurisdiction of US Clean Water Act

Cited by 4 publications

References 2 publications

Patterns of Wetland Hydrologic Connectivity Across Coastal‐Plain Wetlandscapes

Patterns of Wetland Hydrologic Connectivity Across Coastal‐Plain Wetlandscapes

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

Changes in Water Age During Dry‐Down of a Non‐Perennial Stream

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