Analysis and synthesis of headwater streamflow modeling and downstream effects
Active
By John Wesley Powell Center for Analysis and Synthesis
January 1, 2023
There is a critical need for improved headwater stream modeling as headwaters are vulnerable to loss, destruction, or hydrologic alterations.
There is a critical need for improved headwater stream modeling as headwaters are vulnerable to loss, destruction, or hydrologic alterations. Advancing the science of headwater hydrology and their connections and effects downstream will better inform management of these systems. To help meet this need, an EPA-USGS Joint Headwaters Working Group will organize an analysis and synthesis of modeling headwater streamflow and downstream effects across CONUS, identify where gaps and challenges exist in our current streamflow modeling and consider downstream hydrological effects. While we hope to have multiple in-person meetings, the first meeting (July 2023 – outlined more below) will focus on developing the conceptual framework and synthesizing the current state of the science on process-based and statistical hydrological models for headwater streamflow characterization. A subsequent meeting would focus on quantifying downstream effects of headwaters on flooding, drought, and baseflow, concurrently assessing the effects of scale and spatial resolution on outcomes.
Principal Investigators:
Kris Jaeger (USGS)
Roy Sando (USGS)
Jay Christensen (EPA)
Heather Golden (EPA)
Charles Lane (EPA)
Tyler Mahoney (University of Louisville)
Publications:
Golden, H.E., Christensen, J.R., McMillan, H.K., Kelleher, C.A., Lane, C.R., Husic, A., Li, L., Ward, A.S., Hammond, J., Seybold, E.C., Jaeger, K.L., Zimmer, M., Sando, R., Jones, C.N., and others, 2025, Advancing the science of headwater streamflow for global water protection: Nature Water, v. 3, no. 1, p. 16–26, https://doi.org/10.1038/s44221-024-00351-1.
Hammond, J., Christensen, J., Jaeger, K., Sando, R., and Zwart, J., 2026, A Hybrid Approach for Revealing Headwater Hydrology: Eos, v. 107, https://doi.org/10.1029/2026EO260248.
Lane, C.R., D’Amico, E., Christensen, J.R., Golden, H.E., Cheng, F.Y., Hammond, J.C., Husic, A., Jaeger, K.L., Jones, C.N., Kelleher, C.A., Li, L., Mahoney, D.T., McMillan, H.K., Price, A.N., and others, 2026, Identifying Headwater Streams across the Conterminous United States: Ecosystems, v. 29, no. 1, p. 22, https://doi.org/10.1007/s10021-025-01041-z.
Sando, R., Jaeger, K.L., Kelleher, C.A., Hammond, J., Christensen, J.R., Segura, C., Golden, H.E., Cheng, F., Husic, A., Jones, C.N., Lane, C.R., Li, L., Mahoney, D.T., McMillan, H.K., and others, 2026, Streamflow and Surface‐Water Presence Data Availability Across the Conterminous United States: A Review for Headwater Systems: Hydrological Processes, v. 40, no. 5, p. e70572, https://doi.org/10.1002/hyp.70572.
Seybold, E.C., Hammond, J., Husic, A., McMillan, H., Golden, H., Christensen, J.R., Segura, C., Zimmer, M., Price, A.N., Jaeger, K., Li, L., Mahoney, D.T., Cheng, F., Jones, C.N., Kelleher, C., Sando, R., Lane, C., and Ward, A., 2026, Emergent headwater types for watershed monitoring, research, and planning: Geophysical Research Letters, v. 53, no. 17, e2026GL123244, 12 p., https://doi.org/10.1029/2026GL123244.
Seybold, E.C., Hammond, J., Husic, A., McMillan, H., Golden, H., Christensen, J.R., Segura, C., Zimmer, M., Price, A.N., Jaeger, K., Li, L., Mahoney, D.T., Cheng, F., Jones, C.N., Kelleher, C., Sando, R., Lane, C., and Ward, A., 2026, Emergent headwater types for watershed monitoring, research, and planning: Geophysical Research Letters, v. 53, no. 17, e2026GL123244, 12 p., https://doi.org/10.1029/2026GL123244.
Data:
Sando, T.R., Jaeger, K.L., and Hammond, J.C., 2026, Streamflow and Surface-water Presence Data in the Conterminous United States, 1857-2023: U.S. Geological Survey, accessed June 1, 2026, at https://doi.org/10.5066/P1UKMGYR.
Streamflow and Surface-water Presence Data in the Conterminous United States, 1857-2023 Streamflow and Surface-water Presence Data in the Conterminous United States, 1857-2023
This data release includes information on data from 72 streamflow or surface-water presence datasets in the Conterminous United States. It includes location, dataset, parent dataset or publication, site identification (if available), start year, end year, number of years, number of days, frequency of data collection, Strahler stream order, and headwater status.
Emergent headwater types for watershed monitoring, research, and planning Emergent headwater types for watershed monitoring, research, and planning
Headwaters—that is headwater streams and the watersheds they drain—strongly influence water quality, ecosystem services, and hydrologic connectivity, yet remain poorly mapped, monitored, and understood at large spatial scales. Using available spatial data to classify headwater “types” could therefore enhance the utility of sparse monitoring data to advance research and watershed planning...
Authors
Erin C. Seybold, John C. Hammond, Admin Husic, Hilary McMillan, Heather Golden, Jay R. Christensen, Catalina Segura, Margaret Zimmer, Adam N. Price, Kristin Jaeger, Li Li, D. Tyler Mahoney, Fred Cheng, C. Nathan Jones, Christa Kelleher, Roy Sando, Chuck Lane, Adam Ward
A hybrid approach for revealing headwater hydrology A hybrid approach for revealing headwater hydrology
Coordinated work to compile existing data and apply models pairing physical understanding with machine learning could substantially improve streamflow predictions for little-known headwater basins.
Authors
John C. Hammond, Jay R. Christensen, Kristin Jaeger, Roy Sando, Jacob Aaron Zwart
Streamflow and surface-water presence data availability across the conterminous United States: A review for headwater systems Streamflow and surface-water presence data availability across the conterminous United States: A review for headwater systems
Water is essential for life on Earth, supporting ecosystems, human health, and economic activities. Hydrology relies on observational data, and this paper discusses regional and national datasets for the conterminous United States (CONUS) publicly available as of 2023, focusing on headwaters, defined as first- and second-order streams at 1:24000 scale. It identifies 72 primary and...
Authors
Roy Sando, Kristin Jaeger, Christa Kelleher, John C. Hammond, Jay R. Christensen, Catalina Segura, Heather E. Golden, Frederick Y. Cheng, Admin Husic, C. Nathan Jones, Charles R. Lane, Li Li, D. Tyler Mahoney, Hillary McMillan, Adam N. Price, Erin C. Seybold, Adam Ward, Margaret Zimmer, Steven James Pestana
Identifying headwater streams across the conterminous United States Identifying headwater streams across the conterminous United States
Headwater streams play critical roles in hydrologic and biogeochemical processes and functions, yet their spatial distribution and land cover context remain poorly understood at continental scales, and no dedicated geospatial dataset exists. Building from a high-resolution conterminous United States (CONUS) hydrography network dataset, we quantified the spatial extent, density, and...
Authors
Charles R. Lane, Ellen D’Amico, Jay R. Christensen, Heather E. Golden, Frederick Y. Cheng, John C. Hammond, Admin Husic, Kristin L. Jaeger, C. Nathan Jones, Christa A. Kelleher, Li Li, D. Tyler Mahoney, Hilary K. McMillan, Adam N. Price, Roy Sando, Catalina Segura, Erin C. Seybold, Adam S. Ward, Margaret Zimmer
Advancing the science of headwater streamflow for global water protection Advancing the science of headwater streamflow for global water protection
The protection of headwater streams faces increasing challenges, exemplified by limited global recognition of headwater contributions to watershed resiliency and a recent US Supreme Court decision limiting federal safeguards. Despite accounting for ~77% of global river networks, the lack of adequate headwaters protections is caused, in part, by limited information on their extent and...
Authors
Heather E. Golden, Jay Christiensen, Hilary McMillan, Christa A. Kelleher, Charles R. Lane, Admin Husic, Li Li, Adam S. Ward, John C. Hammond, Erin C. Seybold, Kristin L. Jaeger, Margaret Ann Zimmer, Roy Sando, C. Nathan Jones, Catalina Segura, D. Tyler Mahoney, Adam N. Price, Frederick Chang
There is a critical need for improved headwater stream modeling as headwaters are vulnerable to loss, destruction, or hydrologic alterations.
There is a critical need for improved headwater stream modeling as headwaters are vulnerable to loss, destruction, or hydrologic alterations. Advancing the science of headwater hydrology and their connections and effects downstream will better inform management of these systems. To help meet this need, an EPA-USGS Joint Headwaters Working Group will organize an analysis and synthesis of modeling headwater streamflow and downstream effects across CONUS, identify where gaps and challenges exist in our current streamflow modeling and consider downstream hydrological effects. While we hope to have multiple in-person meetings, the first meeting (July 2023 – outlined more below) will focus on developing the conceptual framework and synthesizing the current state of the science on process-based and statistical hydrological models for headwater streamflow characterization. A subsequent meeting would focus on quantifying downstream effects of headwaters on flooding, drought, and baseflow, concurrently assessing the effects of scale and spatial resolution on outcomes.
Principal Investigators:
Kris Jaeger (USGS)
Roy Sando (USGS)
Jay Christensen (EPA)
Heather Golden (EPA)
Charles Lane (EPA)
Tyler Mahoney (University of Louisville)
Publications:
Golden, H.E., Christensen, J.R., McMillan, H.K., Kelleher, C.A., Lane, C.R., Husic, A., Li, L., Ward, A.S., Hammond, J., Seybold, E.C., Jaeger, K.L., Zimmer, M., Sando, R., Jones, C.N., and others, 2025, Advancing the science of headwater streamflow for global water protection: Nature Water, v. 3, no. 1, p. 16–26, https://doi.org/10.1038/s44221-024-00351-1.
Hammond, J., Christensen, J., Jaeger, K., Sando, R., and Zwart, J., 2026, A Hybrid Approach for Revealing Headwater Hydrology: Eos, v. 107, https://doi.org/10.1029/2026EO260248.
Lane, C.R., D’Amico, E., Christensen, J.R., Golden, H.E., Cheng, F.Y., Hammond, J.C., Husic, A., Jaeger, K.L., Jones, C.N., Kelleher, C.A., Li, L., Mahoney, D.T., McMillan, H.K., Price, A.N., and others, 2026, Identifying Headwater Streams across the Conterminous United States: Ecosystems, v. 29, no. 1, p. 22, https://doi.org/10.1007/s10021-025-01041-z.
Sando, R., Jaeger, K.L., Kelleher, C.A., Hammond, J., Christensen, J.R., Segura, C., Golden, H.E., Cheng, F., Husic, A., Jones, C.N., Lane, C.R., Li, L., Mahoney, D.T., McMillan, H.K., and others, 2026, Streamflow and Surface‐Water Presence Data Availability Across the Conterminous United States: A Review for Headwater Systems: Hydrological Processes, v. 40, no. 5, p. e70572, https://doi.org/10.1002/hyp.70572.
Seybold, E.C., Hammond, J., Husic, A., McMillan, H., Golden, H., Christensen, J.R., Segura, C., Zimmer, M., Price, A.N., Jaeger, K., Li, L., Mahoney, D.T., Cheng, F., Jones, C.N., Kelleher, C., Sando, R., Lane, C., and Ward, A., 2026, Emergent headwater types for watershed monitoring, research, and planning: Geophysical Research Letters, v. 53, no. 17, e2026GL123244, 12 p., https://doi.org/10.1029/2026GL123244.
Seybold, E.C., Hammond, J., Husic, A., McMillan, H., Golden, H., Christensen, J.R., Segura, C., Zimmer, M., Price, A.N., Jaeger, K., Li, L., Mahoney, D.T., Cheng, F., Jones, C.N., Kelleher, C., Sando, R., Lane, C., and Ward, A., 2026, Emergent headwater types for watershed monitoring, research, and planning: Geophysical Research Letters, v. 53, no. 17, e2026GL123244, 12 p., https://doi.org/10.1029/2026GL123244.
Data:
Sando, T.R., Jaeger, K.L., and Hammond, J.C., 2026, Streamflow and Surface-water Presence Data in the Conterminous United States, 1857-2023: U.S. Geological Survey, accessed June 1, 2026, at https://doi.org/10.5066/P1UKMGYR.
Streamflow and Surface-water Presence Data in the Conterminous United States, 1857-2023 Streamflow and Surface-water Presence Data in the Conterminous United States, 1857-2023
This data release includes information on data from 72 streamflow or surface-water presence datasets in the Conterminous United States. It includes location, dataset, parent dataset or publication, site identification (if available), start year, end year, number of years, number of days, frequency of data collection, Strahler stream order, and headwater status.
Emergent headwater types for watershed monitoring, research, and planning Emergent headwater types for watershed monitoring, research, and planning
Headwaters—that is headwater streams and the watersheds they drain—strongly influence water quality, ecosystem services, and hydrologic connectivity, yet remain poorly mapped, monitored, and understood at large spatial scales. Using available spatial data to classify headwater “types” could therefore enhance the utility of sparse monitoring data to advance research and watershed planning...
Authors
Erin C. Seybold, John C. Hammond, Admin Husic, Hilary McMillan, Heather Golden, Jay R. Christensen, Catalina Segura, Margaret Zimmer, Adam N. Price, Kristin Jaeger, Li Li, D. Tyler Mahoney, Fred Cheng, C. Nathan Jones, Christa Kelleher, Roy Sando, Chuck Lane, Adam Ward
A hybrid approach for revealing headwater hydrology A hybrid approach for revealing headwater hydrology
Coordinated work to compile existing data and apply models pairing physical understanding with machine learning could substantially improve streamflow predictions for little-known headwater basins.
Authors
John C. Hammond, Jay R. Christensen, Kristin Jaeger, Roy Sando, Jacob Aaron Zwart
Streamflow and surface-water presence data availability across the conterminous United States: A review for headwater systems Streamflow and surface-water presence data availability across the conterminous United States: A review for headwater systems
Water is essential for life on Earth, supporting ecosystems, human health, and economic activities. Hydrology relies on observational data, and this paper discusses regional and national datasets for the conterminous United States (CONUS) publicly available as of 2023, focusing on headwaters, defined as first- and second-order streams at 1:24000 scale. It identifies 72 primary and...
Authors
Roy Sando, Kristin Jaeger, Christa Kelleher, John C. Hammond, Jay R. Christensen, Catalina Segura, Heather E. Golden, Frederick Y. Cheng, Admin Husic, C. Nathan Jones, Charles R. Lane, Li Li, D. Tyler Mahoney, Hillary McMillan, Adam N. Price, Erin C. Seybold, Adam Ward, Margaret Zimmer, Steven James Pestana
Identifying headwater streams across the conterminous United States Identifying headwater streams across the conterminous United States
Headwater streams play critical roles in hydrologic and biogeochemical processes and functions, yet their spatial distribution and land cover context remain poorly understood at continental scales, and no dedicated geospatial dataset exists. Building from a high-resolution conterminous United States (CONUS) hydrography network dataset, we quantified the spatial extent, density, and...
Authors
Charles R. Lane, Ellen D’Amico, Jay R. Christensen, Heather E. Golden, Frederick Y. Cheng, John C. Hammond, Admin Husic, Kristin L. Jaeger, C. Nathan Jones, Christa A. Kelleher, Li Li, D. Tyler Mahoney, Hilary K. McMillan, Adam N. Price, Roy Sando, Catalina Segura, Erin C. Seybold, Adam S. Ward, Margaret Zimmer
Advancing the science of headwater streamflow for global water protection Advancing the science of headwater streamflow for global water protection
The protection of headwater streams faces increasing challenges, exemplified by limited global recognition of headwater contributions to watershed resiliency and a recent US Supreme Court decision limiting federal safeguards. Despite accounting for ~77% of global river networks, the lack of adequate headwaters protections is caused, in part, by limited information on their extent and...
Authors
Heather E. Golden, Jay Christiensen, Hilary McMillan, Christa A. Kelleher, Charles R. Lane, Admin Husic, Li Li, Adam S. Ward, John C. Hammond, Erin C. Seybold, Kristin L. Jaeger, Margaret Ann Zimmer, Roy Sando, C. Nathan Jones, Catalina Segura, D. Tyler Mahoney, Adam N. Price, Frederick Chang