The Rapanos / Carabell Supreme Court Decision
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The Rapanos / Carabell Supreme Court Decision and Implications for Jurisdiction under the Clean Water Act

The landmark Rapanos and Carabell (Rapanos) case addressed the geographic extent of Federal jurisdiction under the Clean Water Act (CWA).  The decision and aftermath have altered the implementation of the Act nationwide.  Rather than clarifying the geographic extent of Federal jurisdiction under the CWA, the Supreme Court’s 2006 decision in the combined cases has led to more questions for regulatory / resource agencies and the regulated public.  The Environmental Protection Agency (EPA) and the Army Corps of Engineers (Corps) issued joint Guidance in 2007 instructing their field staff on implementing the decision.  It is currently unclear if that Guidance is leading to fewer or greater wetlands and waters being protected today than before Rapanos.  What is certain is that the current state of CWA implementation remains unsettled and may be addressed through further rulemaking by the Corps and EPA or through an act of Congress.


Issues Raised in Rapanos / Carabell:  

The case was a consolidation of two Michigan cases from the 6th Circuit Court of Appeals: Rapanos vs. United States, and Carabell vs. U.S. Army Corps of Engineers.  The cases were consolidated because they raised similar questions, with both claiming that wetlands on their properties were not subject to Federal jurisdiction.At issue in Carabell was whether Federal jurisdiction applies to wetlands adjacent to, but hydrologically isolated from any tributary of a water of the United States.  The central question in Rapanos was whether wetlands that do not physically abut navigable-in-fact waters were jurisdictional.


The Supreme Court’s Decision 

By a 5-4 split, the Supreme Court vacated the lower court’s judgments and remanded them back to the 6th Circuit Court of Appeals.  Although there were 5 votes to remand, no single set of underlying legal principles for doing so was supported by a majority of justices.  In effect, it was a “4-1-4” decision:

The plurality:
Justices Alito, Thomas and Chief Justice Roberts joined a plurality opinion written by Justice Scalia.  It held that the government inappropriately applied the CWA by claiming jurisdiction over wetlands beyond the intent of Congress.  Scalia wrote that Federal jurisdiction extended only as far as wetlands adjacent to waters that are “relatively permanent, standing or flowing” and defined adjacency as “having a continuous surface connection.”  In this view, wetlands associated with intermittent streams, for example, may not be considered jurisdictional.

Justice Kennedy:
Kennedy wrote a separate opinion concurring with the plurality, in judgment only, that the cases be remanded.  He did not concur with the plurality on the limits of Federal jurisdiction, instead finding common ground with the dissent.  He remanded because the lower court did not appropriately apply a “significant nexus” test to determine if the wetlands in question were linked to navigable waters.  Kennedy’s opinion is considered controlling because while he concurred with the plurality, he did so on the narrowest grounds of the justices forming the plurality.

The dissent:
Justices Stevens wrote a dissent joined by Breyer, Ginsburg, and Souter holding that the Corps and EPA had appropriately applied the CWA.


The Agencies’ Response – Post-Rapanos Guidance issued by Corps / EPA, June 2007:

On June 8, 2007, the Corps and EPA issued joint guidance to their staff on implementing the court’s decision.  The court’s split ruling had failed to fully clarify the geographic extent of the CWA but controlling legal principles from Justice Kennedy’s opinion suggested that a demonstrable “significant nexus” with a traditionally navigable water is necessary before asserting Federal jurisdiction.  The guidance provides a framework for conducting case-by-case significant nexus analyses for certain classes of waters. 
The guidance describes waters that the agencies will categorically consider jurisdictional (as per Scalia’s opinion), those they will not, and those waters that will be jurisdictional pending a “significant nexus” test (as per Kennedy’s opinion).

The agencies will generally assert jurisdiction over the following:

    • Traditional navigable waters (TNW)
    • Wetlands adjacent to TNWs (including those without a continuous surface connection)
    • Non-navigable tributaries of TNW that are relatively permanent meaning they flow year-round or have continuous flow at least seasonally (typically 3 months)
    • Wetlands adjacent to such tributaries that have a continuous surface connection to the tributaries (i.e. not “separated”)

The agencies generally will not assert jurisdiction over the following:

    • Swales or erosional features with low volume and infrequent or short-duration flow
    • Ditches, excavated wholly in and draining only uplands and without relatively permanent flow.

The agencies will assert jurisdiction over the following pending a significant nexus test:

    • Tributaries that are non-navigable and not relatively permanent (i.e. ephemeral streams, and many intermittent streams)
    • Wetlands adjacent to tributaries that are non-navigable, and not relatively permanent
    • Wetlands adjacent to, but not directly abutting a relatively permanent non-navigable tributary.

Significant nexus analysis:

    • Analyses will consider flow characteristics and functions of a tributary and any adjacent wetlands to determine if they significantly affect the chemical, physical and biological integrity of a TNW.
    • Hydrologic factors considered will include the volume, duration, and frequency of flow
    • Ecological factors of the tributary will be considered: pollutant and flood carrying/storing capacity; habitat and lifecycle support functions for fish and other spp. present in the TNW; nutrient and organic carbon transfer capacity; other relationships to the integrity of the TNW.

Which nexuses are significant?:

    • To “significantly affect” is defined in the guidance as having a “more than speculative” or “more than insubstantial” affect.  These terms, derived directly from Kennedy’s opinion are not further defined or described in the guidance, presumably allowing individual Districts to interpret them on a discretionary basis.

USFWS Response to Post-Rapanos Guidance:

The Service appreciates the agencies’ attempt to create a framework for that is consistent with both the Act and a complex and fractured Supreme Court decision.  However, in a Department of Interior comment letter of February 5, 2008 (available below), the Service noted its concern that broad discretionary language in the guidance and in the new Jurisdictional Determination form is open to subjective interpretation by individual Corps Districts.  The Service acknowledged the difficulty in establishing national thresholds or magnitudes for the significant nexus analysis factors but recommended that EPA and the Corps develop sideboards or thresholds on an eco-regional basis.  This step would recognize that factors influencing hydrology and ecological function vary greatly depending on eco-region and may lead to more consistent implementation of the guidance nationally.  Barring such steps, the Service is concerned that if the guidance is implemented inconsistently, increased wetland impacts will result.


Congressional Response to Rapanos / Carabell:

A bill is currently introduced in Congress that some believe would rectify the ongoing situation of uncertainty regarding what waters are subject to Federal jurisdiction under the CWA.  The bill, H.R. 2421 / S. 1870, introduced by Representative James Oberstar and Senator Russ Feingold, has existed since the SWANCC case in 2001 but has garnered increased attention since Rapanos.  Numerous hearings have been held in 2007 and 2008 by both the Senate Environment and Public Works Committee and the House Transportation and Infrastructure Committee. 

The intent of the bill (full text available below) is to return jurisdiction to a pre-Rapanos, pre-SWANCC status without extending Federal authority; to reaffirm 1972 congressional intent; to clearly define what waters are subject to CWA jurisdiction; and to protect waters to the fullest extent of congressional authority.  It would do so by striking the statutory definition at CWA sec. 502 (7): “The term “navigable waters” means the waters of the United States, including the territorial seas.”  A replacement definition would be added at section 502 (24):  “WATERS OF THE UNITED STATES− The term "waters of the United States" means all waters subject to the ebb and flow of the tide, the territorial seas, and all interstate and intrastate waters and their tributaries, including lakes, rivers, streams (including intermittent streams), mudflats, sandflats, wetlands, sloughs, prairie potholes, wet meadows, playa lakes, natural ponds, and all impoundments of the foregoing, to the fullest extent that these waters, or activities affecting these waters, are subject to the legislative power of Congress under the Constitution.”

Additional Rapanos / Carabell Resources

Army Corps of Engineer’s

EPA’s post-Rapanos (website)

Association of State Wetland Managers’ Rapanos /Carabell (website)

Rapanos / Carabell Documents

DOI comment letter on post-Rapanos Guidance

Supreme Court Opinion, June 19, 2006

Rapanos PowerPoint J.Miller 4/17/08


Clean Water Restoration Act HR2421

House Transportation and Infrastructure

Senate Environment and Public Works


Last updated: February 25, 2013
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