The U.S. Army Corps of Engineers (Corps), Sacramento, San Francisco, Los Angeles, and Albuquerque Districts (South Pacific Division), the Corps Omaha District, and the U.S. Environmental Protection Agency (EPA), Regions 6 , 8, and 9 jointly announce the availability of the Beta Streamflow Duration Assessment Method (SDAM) for the Arid West (dated February 2021). The method is a rapid assessment tool to help distinguish between ephemeral, intermittent, and perennial streamflow at the reach scale. The SDAM may help in providing technical guidance for identifying waters that may be subject to regulatory jurisdiction under the Clean Water Act; however, this method does not imply or represent a change in the definition of “Waters of the U.S.”