The U.S. Army Corps of Engineers (Corps) Albuquerque, Chicago, Detroit, Fort Worth, Galveston, Kansas City, Omaha, Rock Island, St. Louis, St. Paul, and Tulsa Districts, and the U.S. Environmental Protection Agency (EPA), Regions 5, 6, 7, and 8, jointly announce the availability of the Beta Streamflow Duration Assessment Method (SDAM) for the Great Plains (dated September 2022). The method is a rapid assessment tool to help distinguish between ephemeral, intermittent, and perennial streamflow at the reach scale for the Northern and Southern Great Plains SDAM Regions. The beta SDAM may help provide 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 alter or change the definition of “Waters of the U.S.”
The beta SDAM was developed for use in all or part of the states of Colorado, Illinois, Iowa, Kansas, Michigan, Minnesota, Missouri, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas, Wisconsin, and Wyoming by the Corps and EPA (Figure 1). This beta method results from a literature review and field study conducted at 251 stream reaches across the range of hydrologic landscapes of the Great Plains from 2019 to 2021. Developed through statistical analyses of the field data, it provides a data-driven approach using nine reliable indicators to determine streamflow duration class at the reach scale. The agencies are making this beta SDAM available for a one-year preliminary implementation and comment period to inform the development of a final SDAM for the Great Plains.
The method, data forms, and training opportunities are available on the internet at:
https://www.epa.gov/streamflow-duration-assessment/beta-streamflow-duration-assessment-method-great-plains.
For additional information on the development of regional Streamflow Duration Assessment Methods
for nationwide coverage, see: https://www.epa.gov/streamflow-duration-assessment.
Written comments may be submitted via email to USACE.SDAM.GP@usace.army.mil or by hard copy to: U.S. Army Corps of Engineers, Attn: CECW-CO-R, 441 G Street NW, Washington, DC 20314-1000.
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