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Development of Rapid Streamflow Duration Assessment Methods for Nationwide Coverage

Thursday, April 13, 2023 - 3:00 p.m. - 4:30 p.m. EDT Register Here


  • Brian Topping, U.S. Environmental Protection Agency, Office of Wetlands, Oceans and Watersheds
  • Tracie Nadeau, U.S. Environmental Protection Agency, Region 10


Practitioners and regulated entities need rapid, reach-scale methods to classify streamflow duration to implement and comply with many federal, state, and local programs. The U.S. Environmental Protection Agency, working cooperatively with the U.S. Army Corps of Engineers, is developing regional streamflow duration assessment methods (SDAMs) for nationwide coverage. These SDAMs use hydrological, geomorphological, and biological indicators, observable in a single site visit to classify reaches as perennial, intermittent, or ephemeral ( We present five regional beta methods that resulted from multi-year studies conducted nationwide and included the evaluation of 141 candidate indicators expected to control or respond to streamflow duration at reaches of known streamflow duration class. To maximize classification accuracy, each regional SDAM relies on a different suite of indicators resulting from machine learning applied to regional datasets. Beta SDAMs will be re-evaluated considering user comments and additional data to produce final methods in 2023-24. We will describe the SDAM development process, including data analysis and management, highlight similarities and differences between the regional SDAMs, invite user comment on the beta methods, and discuss opportunities for more refined regionalization.


Brian Topping, U.S. Environmental Protection AgencyBrian Topping has worked at the U.S. Environmental Protection Agency since 2004 primarily in the Clean Water Act Section 404 regulatory program for the discharge of dredge and fill material in waters of the United States. Brian began working on streamflow duration assessment method development in 2007 in Oregon and currently leads the project delivery team for the development of rapid field-based streamflow duration assessment methods at EPA. He also works on stream mitigation assessment methods, program tracking and reporting, program training, and compensatory mitigation.


Tracie Nadeau, U.S. Environmental Protection AgencyTracie Nadeau is an Environmental Scientist with the U.S. Environmental Protection Agency, Region 10 (Pacific Northwest), Tracie Nadeau is currently on detail to EPA Headquarters’ Office of Wetlands, Oceans and Watersheds (OWOW) as a core member of the small team developing Streamflow Duration Assessment Methods (SDAMs) for nationwide coverage. She began working on streamflow duration assessment method development in 2007 when she led the development of an SDAM for the Pacific Northwest. Tracie is a broadly trained aquatic ecologist with over 20 years of experience working at the science-policy interface, synthesizing and communicating state of the science on aquatic resource issues, implementing programs, and developing and coordinating applied research projects. In her Region 10 Oregon Operations home office, she works on stream, wetland, watershed, and mitigation issues, including working with state and tribal partners to build program capacity and develop science-based tools supporting program implementation.

  Register Here