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Corps and EPA Issue, Seek Comment On, Post-Rapanos Guidance

By: Paul S. Weiland

On June 5, 2007 the Army Corps of Engineers ("Corps") and the Environmental Protection Agency ("EPA") (collectively "Agencies") issued long-awaited guidance to address the June 2006 decision of the United States Supreme Court in Rapanos v. United States and Carabell v. United States Army Corps of Engineers, 126 S.Ct. 2208 (2006) (hereinafter "Rapanos") regarding the scope of the Agencies' jurisdiction under the section 404 of the Clean Water Act.  

The guidance, entitled "Clean Water Act Jurisdiction Following the U.S. Supreme Court's Decision in Rapanos v. United States & Carabell v. United States" ("Guidance") provides some clarity in determining what wetland and drainage features may be subject to Corps jurisdiction by identifying those circumstances in which the Agencies assume water features are jurisdictional, those circumstances in which the Agencies will apply a so-called significant nexus standard to determine jurisdiction, and those circumstances in which the Agencies will assume they do not have jurisdiction.  Click here to view the Guidance in its entirety. 

The Guidance makes clear the Agencies' view that "regulatory jurisdiction under the Clean Water Act exists over a water body if either the plurality's or Justice Kennedy's [significant nexus] standard is justified."  The Guidance also clarifies the Agencies' interpretation of the Supreme Court's decision with regard to when a "significant nexus" determination is required to assert jurisdiction under the test asserted by Justice Kennedy in Rapanos, and the factors that should be considered in determining whether a "significant nexus" exists. 

The following are the some of the most important aspects of the Guidance:

Jurisdiction will continue to be asserted over the following:

  • Traditional navigable waters;
  • Wetlands adjacent to traditional navigable waters, including those that do not have a continuous surface connection to traditional navigable waters;
  • Relatively permanent non-navigable tributaries of traditional navigable waters; and
  • Wetlands that abut relatively permanent non-navigable tributaries of traditional navigable waters.   

"Relatively permanent" is defined in the Guidance as "waters that typically (e.g., except due to drought) flow year-round or waters that have a continuous flow at least seasonally (e.g., typically three months)"; this does not include ephemeral tributaries which flow only in response to precipitation.

A significant nexus analysis and determination will be required to assert jurisdiction over the following:

  • Non-navigable tributaries that are not relatively permanent;
  • Wetlands adjacent to non-navigable tributaries that are not relatively permanent; and
  • Wetlands adjacent to, but that do not directly abut, a relatively permanent non-navigable tributary.

Factors to be considered in assessing whether a water has a significant nexus with a traditional navigable water include:

  • Volume, duration and frequency of flow;
  • Physical characteristics of the tributary;
  • Proximity to the traditional navigable water;
  • Size of the watershed;
  • Average annual rainfall and winter snowpack;
  • Potential of tributaries to carry pollutants and flood waters to traditional navigable waters;
  • Provision of aquatic habitat that supports a traditional navigable water;
  • Potential of wetlands to trap and filter pollutants or store flood waters; and
  • Maintenance of water quality in traditional navigable waters. 

Jurisdiction will not be asserted over the following:

  • Swales or erosional features (small washes characterized by infrequent, low volume); and
  • Ditches excavated wholly in and draining only uplands that do not carry a relatively permanent flow of water. 

The Guidance provides that in certain situations ephemeral waters in the arid west are distinguishable from the swales and erosional features that the Agencies have determined are not jurisdictional.  Where such ephemeral streams perform biological and physical functions that can significantly affect the chemical, physical, and biological integrity of downstream navigable waters, a significant nexus may be found to exist, and thus these types of features may be subject to Corps jurisdiction. 

Although the Guidance will apply immediately to jurisdictional determinations, the Agencies are seeking public comment on the Guidance for a period of six months.  Notably, the Agencies plan to reissue, revise, or suspend the Guidance within nine months.  In the meantime, the Guidance will be useful to entities that may be subject to regulation under section 404 of the Clean Water Act.  Following the Guidance will allow such entities to undertake a technical analysis which may provide a basis for the Corps to determine that such features are not subject to Corps jurisdiction.  The significant nexus framework set out in the Guidance is similar to analyses we, in collaboration with consultants, have already been doing to assist our clients in determining whether certain drainages and wetlands are subject to Corps jurisdiction. 


Paul Weiland counsels clients regarding environmental and land use matters and litigates such matters in trial and appellate courts under a variety of statutes, including the Clean Water Act and Endangered Species Act.  Formerly, he worked in the Law and Policy Section, Environmental and Natural Resources Division of the U.S. Department of Justice.  He can be reached at (949) 833-7800 or

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