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On November 18, 2021 the U.S. Environmental Protection Agency and the Department of the Army announced the signing of a proposed rule to revise the definition of Waters of the United States

Regulatory Program Notices

Below are regulatory announcements, in chronological order, which are both current and historical. Current announcements provide information regarding ongoing regulatory processes and happenings. Historical announcements remain posted, as long as they remain up-to-date and applicable, to provide the public with a transparent record of changes and improvements to our program.   Regulatory image of trees over a creek

Notice of Availability of the Streamflow Duration Assessment Method for the Pacific Northwest

Portland District
Published Feb. 25, 2016

Issue Date: February 25, 2016

The U.S. Army Corps of Engineers (Corps), Seattle, Walla Walla, and Portland districts and the U.S. Environmental Protection Agency, Region 10 (EPA) jointly announce the availability of the Streamflow Duration Assessment Method (SDAM) for the Pacific Northwest (dated November 2015).  The method is a rapid assessment tool to help document streamflow duration and distinguish between ephemeral, intermittent, and perennial streams. The SDAM may help in providing technical guidance for identifying waters that may be subject to regulatory jurisdiction under Section 404 of the Clean Water Act; however this method does not affect the definition of “Waters of the U.S.”

This announcement extends the applicability of this tool to the Pacific Northwest. SDAM was developed for use in the state of Oregon by the Corps, EPA, and the Oregon Department of State Lands in 2011. This current method results from a validation study conducted in two phases on 264 stream reaches across the range of hydrologic landscapes of Oregon, Idaho, and Washington from 2008 to 2012. Developed through statistical analyses of field data, it provides a simplified approach using seven reliable indicators to provide information on streamflow duration.

The SDAM can be applied whenever there is uncertainty regarding streamflow duration and a rapid method of evaluation is desired. The method provides a scientifically supported, rapid assessment framework to support best professional judgment in a consistent, robust, repeatable and defensible way. Use of the method may result in more timely and predictable jurisdictional determinations, and is also useful where knowledge of streamflow duration improves ecological assessment, management, and decision-making.

The method and data forms are available on the internet at:

For additional information, contact the Corps or the EPA:

Portland District, Peter Olmstead, 541-962-0401, Peter.D.Olmstead@usce.army.mil
Seattle District, Jess Jordan, 206-316-3967, Dale.J.Jordan@usace.army.mil
Walla Walla District, Robert Brochu, 208-522-1645, Robert.A.Brochu@usace.army.mil or Christen Marve Griffith, 208-433-4470, Christen.M.Griffith@usace.army.mil

Tracie Nadeau, 503-326-3685, Nadeau.Tracie@epa.gov