Beta Streamflow Duration Assessment Method for the Great Plains
The beta Streamflow Duration Assessment Method (SDAM) for the Great Plains is a scientific tool to provide a rapid assessment framework to distinguish between ephemeral, intermittent, and perennial stream flow at the reach scale. Using the beta SDAM for the Great Plains to generate a streamflow classification requires entering data into an online tool.
The agencies are making this beta SDAM available for a one-year preliminary implementation period while we conduct a continued data collection effort into 2022 to inform the refinement of the final SDAM for the Great Plains. We welcome user comments during the preliminary implementation period.
On this page:
- What is the method used for?
- How was the method developed?
- Additional information on how to apply the method
- Training opportunities
- Documents and tools
Long-term hydrologic data to assess streamflow duration is often limited, especially for streams that do not flow year-round. SDAMs are rapid field assessment methods that use hydrological, geomorphological, and/or biological indicators, observable in a single site visit, to classify streamflow duration as perennial, intermittent, or ephemeral at the reach scale. Regulators and water resource managers can use rapid, reach-scale methods to determine streamflow duration classifications (i.e., perennial, intermittent, ephemeral) and to help implement many federal, state, and local programs.
For instance, this information could help determine whether a stream reach may be subject to jurisdiction under the Clean Water Act. However, use of the method is not a requirement for determining jurisdiction.
This method is also useful where knowledge of streamflow duration improves ecological assessment, management, and decision-making.
While this method may inform a more robust stream assessment, it was specifically developed to determine streamflow duration class and does not provide a stand-alone assessment of stream function or condition.
This method does not alter or change the definition of Waters of the United States under the Clean Water Act.
Learn more about the development of streamflow duration assessment methods for nationwide coverage, including the steps for developing a regional method.
The beta SDAM for the Great Plains results from a multi-year study conducted at 251 stream reaches across the Great Plains following the process put forward by Fritz et al. (2020). Thirty-one candidate indicators expected to control or respond to streamflow duration were tested at sites of known flow duration class. Through statistical analyses, the agencies identified the subset of indicators with the highest diagnostic accuracy of flow duration classification and constructed the current data-driven beta method. Data collection continued through 2022 to inform the refinement of the final SDAM for the Great Plains.
In October 2023 errors were found in the coding of the beta SDAM calculation of “at least intermittent” classifications. This error has now been corrected in the web application and in the November 2023 updates to the User Manual and supporting documents. Users of the beta SDAM that have resulted in “at least intermittent” classification prior to these updates should consult the updated web application to correct possible errors in their classification results.
A supplemental document describing the data analyses and study data are available in the Documents and Tools section below.
The information below is intended to clarify how to apply certain elements of this method. If you have other questions, feel free to share inquiries with contacts listed below.
1. How is the assessment reach defined for:
1.1 Unconstrained settings:
Assessments should be made over the length of a stream reach, rather than at one point. The assessment reach chosen should be representative of the stream and should have a length equivalent to 40 channel widths. For narrow streams, the length of the assessment reach should be a minimum of 40 meters. The agencies recommend walking the stream prior to choosing an assessment reach.
1.2 Constrained settings (e.g., within highway right-of-way or a single tax lot):
If it is not possible to assess a reach that is 40 channel widths in length, then apply the method for the entire length of stream that you can access. Make a note of your assessment reach length and constraints on the data sheet. If possible, inspect upstream and downstream sections of the stream and make a note of your observations.
2. Are the results from using this method the same as a jurisdictional determination?
No. The regulatory agencies make jurisdictional determinations based on federal law and current guidance and policy, and method outputs are not a jurisdictional determination. Instead, the method provides information that may be useful for the agencies to make timely decisions because it helps determine streamflow duration.
3. Can this method be applied to created or altered channels?
Yes, the method can be used, in combination with best professional judgment, to assess the flow duration of created channels or stream reaches that have been highly modified. The agencies have observed that some hydrologic and biologic indicators tend to persist (wetland plants, for instance, may occur on the margins of the channel) even with frequent maintenance of the created or altered channels. When applying the method in created channels or modified streams, note that the site is a “disturbed site/difficult situation” and describe it in the “notes.”
4. What part of the stream do I assess when working in a braided stream system?
Identify the lateral extent of the channels, based on the outer limits of the ordinary high water marks, and apply the method to that area as a whole. Some indicators may be present or more apparent in the main channel versus the side channels; note those differences on the field assessment form.
5. Is the method applicable when a stream goes subsurface in a portion of the assessment reach?
Streams observed flowing subsurface during the assessment visit may flow on the surface during wetter times of the year; therefore, it is important to check the entire reach for indicators of streamflow. In addition, the accuracy of an assessment can be improved by conducting a follow-up visit during a wetter time of the year. Assessment reach placement should maximize the homogeneity of drivers of streamflow duration (e.g., valley morphology), and should not consider the presence or absence of surface water.
User comments are welcome during the preliminary implementation period. Detailed instructions on how to provide comments are available in the Joint Public Notice of Availability.
- (Region 5) Kerryann Weaver (email@example.com), 312-353-9483
- (Region 6) Loribeth Tanner (firstname.lastname@example.org), 214-665-8153
- (Region 7) Seiji Kuwata (email@example.com), 913-551-7318.
- (Region 8) Rachel Harrington (firstname.lastname@example.org), 303-312-6870
Army Corps of Engineers:
- (Albuquerque District) Kraig Jashinsky, 719-543-9459 X 4, Kraig.A.Jashinsky@usace.army.mil
- (Chicago District) Andrew Blackburn, 312-846-5543, Andrew.J.Blackburn@usace.army.mil
- (Detroit District) Sabrina Miller, 313-226-7495, Sabrina.M.Miller@usace.army.mil
- (Fort Worth District) Joseph Shelnutt, 817-886-1738, Joseph.L.Shelnutt@usace.army.mil
- (Galveston District) Mark Pattillo, 361-814-5847 , Mark.E.Pattillo@usace.army.mil
- (Kansas City District) Matt Mikulecky, 816-389-3027, Matthew.J.Mikulecky@usace.army.mil
- (Omaha District) Karen Lawrence, 402-995-2463, Karen.L.Lawrence@usace.army.mil
- (Rock Island District) Kirsten Brown, 309-794-5369, Kirsten.L.Brown@usace.army.mil
- (St. Louis District) Chad Lamontagne, 314-331-8044, Chad.M.Lamontagne@usace.army.mil
- (St. Paul District) April Marcangeli, 651-290-5731, April.N.Marcangeli@usace.army.mil
- (Tulsa District) Rob Hoffman, 918-669-7481, Robert.B.Hoffman@usace.army.mil
- Updated User Manual for a Beta Streamflow Duration Assessment Method for the Great Plains of the United States (pdf)
- Field form beta Streamflow Duration Assessment Method for the Great Plains updated November 2023 (pdf)
- Updated Development and Evaluation of the Beta Streamflow Duration Assessment Method (SDAM) for the Great Plains (GP) (pdf)
- Updated Online Web Application – an electronic application to obtain a streamflow duration classification based on user-submitted data; also provides users the option to generate a report of their results.
- Data used to develop the Beta SDAM for the Great Plains.
- Joint Public Notice Notice of Availability of the Beta Streamflow Duration Assessment Method for the Great Plains (pdf)
- Review of Flow Duration Methods and Indicators of Flow Duration in the Scientific Literature: Great Plains of the United States (pdf)