Streamflow Duration Assessment Method (SDAM) Status by Region
Currently, the EPA and partners are developing or modifying existing SDAMs for use across the U.S. Watch a webinar presentation about the five regional beta methods that resulted from multi-year studies conducted nationwide.
Map of Study Regions
Map of SDAM study regions, based on regions identified in the U.S. Army Corps of Engineers Ordinary High Water Mark Scientific Support Document (figure modified from Wohl et al. 2016).
Regional Updates
Pacific Northwest
The SDAM for the Pacific Northwest was developed through a partnership between the U.S. EPA, the U.S. Army Corps of Engineers, and Oregon’s Department of State Lands. The method resulted from a study conducted on 264 stream reaches across the range of hydrologic landscapes of Oregon, Idaho, and Washington.
Arid West
The beta SDAM for the Arid West was released in March 2021. The beta method is available for a one-year preliminary implementation period while EPA and partners continue an expanded data collection effort in 2021 to inform the refinement of the final SDAM for the Arid West. The beta method results from a multi-year study conducted at 89 reaches across 7 states in the Arid West.
Western Mountains
A beta method for the Western Mountains was released in December 2021. The beta method results from a multi-year study conducted at 140 stream reaches across 9 states. The beta method is available for a one-year preliminary implementation period while EPA and partners continue an expanded data collection effort in 2022 to inform the refinement of the final SDAM for the Western Mountains.
Great Plains
A beta method for the Great Plains has been released for public review and comment. A total of 251 instrumented and single-visit sites were sampled as part of data collection. During each site visit, a rapid field assessment was conducted using hydrological, geomorphological, and biological candidate indicators of streamflow duration. Thirty-one candidate indicators were identified through a literature review of existing streamflow duration methods and indicators used throughout the U.S. and considered for applicability to the Great Plains. Through statistical analyses a subset of nine indicators with the highest diagnostic accuracy for flow duration classification were identified, which were used to construct the current data-driven method.
Northeast and Southeast
Beta methods for the Northeast and Southeast have been released for public review and comment. These beta methods result from a multi-year field study conducted at 336 stream reaches across 31 states of the Northeast and Southeast. During each reach visit, hydrological, geomorphological, and biological candidate indicators of streamflow duration were assessed. Ninety-seven candidate indicators, including geospatial indicators, were evaluated and considered for applicability in the Northeast and Southeast. Through statistical analyses a subset of indicators with the highest diagnostic accuracy for flow duration classification were identified, which were used to construct the current data-driven methods. Two beta SDAMs were developed and U.S. Caribbean study reaches were not used in the development of the beta SDAM for the Southeast due to increased accuracy when creating separate methods as well as differences in climate and the relatively small number of study reaches in the U.S. Caribbean. The beta SDAM for the Northeast Method uses eight indicators, while the beta SDAM for the Southeast uses seven indicators.
Alaska, Hawaii, and the Pacific Island U.S. Territories
Candidate indicators have been identified through a literature review of existing streamflow duration methods and indicators used throughout the U.S. and considered for applicability in Alaska, Hawaii, and the U.S. Territories in the Pacific Ocean.