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Non-Navigable Streams and Wetlands
Citation:
WIGINGTON JR, P. J. Non-Navigable Streams and Wetlands. U.S. Environmental Protection Agency, Washington, DC, EPA/600/F-09/008, 2009.
Impact/Purpose:
Develop information and methods that could help assess hydrologic permanence and significant nexus.
Description:
In 2006, the US Supreme Court addressed jurisdiction of non-navigable waters and adjacent wetlands (NSW) under the Clean Water Act (CWA). The Rapanos decision resulted in two criteria for determining CWA jurisdiction of NSWs: their hydrological permanence and whether they have a “significant nexus.” In 2008, scientists from EPA’s Western Ecology Division (WED) and colleagues published a paper proposing an approach for examining some of the scientific issues raised by the Rapanos decision. WED’s NSW Project is using this approach to develop information and methods that could help assess hydrologic permanence and significant nexus. The Project’s research includes: field testing of the Oregon Streamflow Duration Assessment Method, which was developed to distinguish between ephemeral, intermittent and perennial streams; and development of a Hydrologic Landscape Regions map for Oregon that could be as part of a system used to classify the effects of NSWs on navigable waters. Such information should help EPA staff identify waters subject to CWA regulatory jurisdiction in light of the Rapanos decision.