I am a Supervisory Research Wildlife Biologist at the Forest and Rangeland Ecosystem Science Center
My research interests include landscape ecology, riverine landscapes, watershed processes, ecological scaling, water quality, fish habitat, land use/land cover change, landscape scenario modeling, spatial analysis, remote sensing and GIS.
Professional Experience
2002 - Present: USGS Forest and Rangeland Ecosystem Science Center, Supervisory Research Wildlife Biologist, Seattle, WA
Education and Certifications
Ph.D., Fisheries Science, Oregon State University, Corvallis, OR (2002)
M.S., Fisheries Science, Geography Minor, Oregon State University, Corvallis, OR (1996)
B.A., Geography/German, double major, University of Oregon, Eugene, OR (1993)
Science and Products
Aquatic & Landscape Ecology Research Team (FRESC)
Aquatic & Landscape Ecology Research Team (FRESC)
Water Temperature in Rivers and Streams
Spatial Ecology of Freshwater Ecosystems
Landscape Patterns and Disturbance
Dam removal: synthesis of ecological and physical responses
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Spatial and temporal variability of summer water temperature at cool-water areas in the Pend Oreille River, Washington
Riverscape snorkeling surveys of salmonid distribution and abundance before (2007, 2008) and after (2018, 2019) dam removal on the Elwha River, Washington
Airborne thermal infrared remote sensing of summer water temperature in the Middle Fork John Day River (Oregon) in 1994-2003
Water temperature data from the Priest River, Idaho, 2018-2019
Stream Temperature and Water Presence Models of Willow/Whitehorse and Willow/Rock Watersheds, Oregon and Nevada
Water temperature data from the Pend Oreille River, Washington and Idaho, 2016-2018
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Spatial and temporal variation of large wood in a coastal river
Closing the gap between science and management of cold-water refuges in rivers and streams
Who spawns where? Temperature, elevation, and discharge differentially affect the distribution of breeding by six Pacific salmonids within a large river basin
Effects of structure and volcanic stratigraphy on groundwater and surface water flow: Hat Creek basin, California, USA
Relocated beaver can increase water storage and decrease stream temperature in headwater streams
Keeping an eye on water quality from the sky
Reconnecting the Elwha River: Spatial patterns of fish response to dam removal
Riverscape approaches in practice: Perspectives and applications
A riverscape approach reveals downstream propagation of stream thermal responses to riparian thinning at multiple scales
Integrating regional and local monitoring data and assessment tools to evaluate habitat conditions and inform river restoration
Integrating thermal infrared stream temperature imagery and spatial stream network models to understand natural spatial thermal variability in streams
Land-cover and climatic controls on water temperature, flow permanence, and fragmentation of Great Basin stream networks
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
To request an interview, contact fresc_outreach@usgs.gov or call (541) 750-1030.
Science and Products
- Science
Aquatic & Landscape Ecology Research Team (FRESC)
Fresh waters are one of the most valuable and threatened resources worldwide. They supply critical services to society and harbor many of the world’s most imperiled species. We conduct research and provide technical assistance to address challenges to fresh waters. Our research focuses on ecological processes in freshwater and terrestrial systems and the effects of those processes on landscape...Aquatic & Landscape Ecology Research Team (FRESC)
Fresh waters are one of the most valuable and threatened resources worldwide. They supply critical services to society and harbor many of the world’s most imperiled species. We conduct research and provide technical assistance to address challenges to fresh waters. Our research focuses on ecological processes in freshwater and terrestrial systems and the effects of those processes on landscape...Water Temperature in Rivers and Streams
Increases in summer stream temperature as a result of human impacts and climate change may exceed the thermal tolerances of aquatic biota that are adapted to colder environments and climates. The combined effects of humans and climate change are of global concern across the range of coldwater aquatic organisms.Spatial Ecology of Freshwater Ecosystems
Water resources, riparian areas, and aquatic organisms are of critical importance in natural resource management. Yet, they are difficult to map, monitor, and understand in a spatially explicit and extensive manner as can be done more easily in terrestrial environments.Landscape Patterns and Disturbance
FRESC scientists investigate whole-system processes and relationships across space and time in order to advance understanding of natural, managed, and disturbed ecosystems. This includes research, monitoring, remote sensing, modeling, and synthesis to describe the patterns of change across landscapes and the biological and physical processes that generate them.Dam removal: synthesis of ecological and physical responses
Dam decommissioning is rapidly emerging as an important river restoration strategy in the U.S., with several major removals recently completed or in progress. But few studies have evaluated the far-reaching consequences of these significant environmental perturbations, especially those resulting from removals of large (>10-15 m tall) structures during the last decade. In particular, interactions b - Data
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Spatial and temporal variability of summer water temperature at cool-water areas in the Pend Oreille River, Washington
The water temperature data were collected in summer 2021. Continuously recording temperature loggers were deployed at the confluences of Indian Creek and Duncan Springs in the Pend Oreille River. Loggers were checked every 1-2 weeks throughout the summer.Riverscape snorkeling surveys of salmonid distribution and abundance before (2007, 2008) and after (2018, 2019) dam removal on the Elwha River, Washington
We used snorkel surveys in the Elwha River, conducted in consecutive years before (2007, 2008) and after (2018, 2019) dam removal to assess changes in fish distribution and density. In total, we counted 54,616 Chinook Salmon, Bull Trout, Steelhead, and trout (Rainbow Trout and Coastal Cutthroat Trout combined) in 22 common reaches spanning 65 river kilometers. The occupancy of juvenile Chinook SalAirborne thermal infrared remote sensing of summer water temperature in the Middle Fork John Day River (Oregon) in 1994-2003
This data release combines seven airborne thermal infrared (TIR) remote sensing data sets of stream temperature collected along the mainstem of the Middle Fork John Day River (MFJD) in Oregon from 1994 to 2003. Years 1994, 1995, 1996, 1998, and 2002 have single datasets. Year 2003 has two data sets. Most of the TIR data covered the upstream half of the MFJD mainstem between river km 50 and 110, whWater temperature data from the Priest River, Idaho, 2018-2019
Water temperature data were collected in summer 2018 and 2019. Temperature data loggers were deployed in tributary confluences and the mainstem of the lower Priest River between Priest Lake Outlet Dam and the confluence with the Pend Oreille River. Data loggers were checked every 2 to 3 weeks throughout the summer. Data for Lagrangian longitudinal thermal profiles were obtained on August 21, 2018Stream Temperature and Water Presence Models of Willow/Whitehorse and Willow/Rock Watersheds, Oregon and Nevada
This data release contains spatial stream network (SSN) objects and R scripts to run SSN models to predict mean monthly stream temperature between May and August and water presence on May 15, June 15, July 15, and August 15 in the Willow/Whitehorse watershed during 2015, 2016, and 2017 and the Willow/Rock watershed during 2016 and 2017. Functions referenced within the script may accessed in the SSWater temperature data from the Pend Oreille River, Washington and Idaho, 2016-2018
The data were collected summer, 2016, 2017, and 2018. Continuous temperature loggers were deployed along the Pend Oreille River between Albeni Falls Dam and the Box Canyon Dam. Loggers were checked every 1-2 weeks throughout the summer. - Multimedia
- Publications
If you are unable to access or download a product, email fresc_outreach@usgs.gov a request, including the full citation, or call (541) 750-1030.
Filter Total Items: 59Spatial and temporal variation of large wood in a coastal river
Large wood (LW) is a critical habitat-forming feature in rivers, but our understanding of its spatial and temporal dynamics remains incomplete due to its historical removal from waterways. Few studies have the necessary spatial and temporal extent and resolution to assess wood dynamics over long time periods or in response to flood disturbance. We used an exceptional dataset from 65 km of a free-fAuthorsKimberly Yazzie, Christian E. Torgersen, Daniel Schindler, Gordon H. ReevesClosing the gap between science and management of cold-water refuges in rivers and streams
Human activities and climate change threaten coldwater organisms in freshwater ecosystems by causing rivers and streams to warm, increasing the intensity and frequency of warm temperature events, and reducing thermal heterogeneity. Cold-water refuges are discrete patches of relatively cool water that are used by coldwater organisms for thermal relief and short-term survival. Globally, cohesive manAuthorsFrancine H. Mejia, Valerie Ouellet, Martin Briggs, Stephanie M. Carlson, Rose Casas-Mulet, Mollie Chapman, Matthias J. Collins, Stephen J. Dugdale, Joseph L. Ebersole, Danielle M. Frechette, Aimee H. Fullerton, Carol-Anne Gillis, Zachary Johnson, Christa Kelleher, Barret L. Kurylyk, Rebecca Lave, Benjamin Letcher, Knut M. Myrvold, Tracie-Lynn Nadeau, Helen Neville, Herve Piégay, Kathryn E. Smith, Diego Tonolla, Christian E. TorgersenWho spawns where? Temperature, elevation, and discharge differentially affect the distribution of breeding by six Pacific salmonids within a large river basin
Within the geographic range of salmonid fishes, many apparently suitable rivers and streams are used for reproduction by some species but not others. This is widely known but seldom addressed, as studies often examine factors determining the distribution of one or only a few species. We examined physical factors associated with the spawning distribution of six native Pacific salmonids (pink, chum,AuthorsCatherine S Austin, Christian E. Torgersen, Thomas P. QuinnEffects of structure and volcanic stratigraphy on groundwater and surface water flow: Hat Creek basin, California, USA
Hydrogeologic systems in the southern Cascade Range in California (USA) develop in volcanic rocks where morphology, stratigraphy, extensional structures, and attendant basin geometry play a central role in groundwater flow paths, groundwater/surface-water interactions, and spring discharge locations. High-volume springs (greater than 3 m3/s) flow from basin-filling (<800 ka) volcanic rocks in theAuthorsMarina Francesca Marcelli, Erick R. Burns, L. J. Patrick Muffler, Andrew J Meigs, Jennifer A. Curtis, Christian E. TorgersenRelocated beaver can increase water storage and decrease stream temperature in headwater streams
Many areas are experiencing increasing stream temperatures due to climate change, and some are experiencing reduced summer stream flows and water availability. Because dam building and pond formation by beaver can increase water storage, stream cooling, and riparian ecosystem resilience, beaver have been proposed as a potential climate adaption tool. Despite the large number of studies that have eAuthorsBenjamin J. Dittbrenner, Jason W. Schilling, Christian E. Torgersen, Joshua J. LawlerKeeping an eye on water quality from the sky
You can learn a lot about rivers, lakes, estuaries, and oceans by looking down at them from the sky. Scientists use a technique called remote sensing to measure the amount of light or heat energy reflected and emitted from the Earth. Sensors can be on satellites or mounted on airplanes, helicopters, or drones. Scientists use this information to map the quality of water in the San Francisco Bay-DelAuthorsFrancine H. Mejia, Christian E. Torgersen, Cédric G FichotReconnecting the Elwha River: Spatial patterns of fish response to dam removal
The removal of two large dams on the Elwha River was completed in 2014 with a goal of restoring anadromous salmonid populations. Using observations from ongoing field studies, we compiled a timeline of migratory fish passage upstream of each dam. We also used spatially continuous snorkeling surveys in consecutive years before (2007, 2008) and after (2018, 2019) dam removal during summer baseflow tAuthorsJeffrey J. Duda, Christian E. Torgersen, Samuel J. Brenkman, Roger J. Peters, Kathryn T. Sutton, Heidi A. Connor, Philip R. Kennedy, Stephen C. Corbett, Ethan Z. Welty, Anna Geffre, Josh Geffre, Patrick Crain, Dave Shreffler, John R. McMillan, Mike McHenry, George R. PessRiverscape approaches in practice: Perspectives and applications
Landscape perspectives in riverine ecology have been undertaken increasingly in the last 30 years, leading aquatic ecologists to develop a diverse set of approaches for conceptualizing, mapping and understanding ‘riverscapes’. Spatiotemporally explicit perspectives of rivers and their biota nested within the socio-ecological landscape now provide guiding principles and approaches in inland fisheriAuthorsChristian E. Torgersen, Céline Le Pichon, Aimee H. Fullerton, Stephen J. Dugdale, Jeffrey J. Duda, Floriane Giovannini, Évelyne Tales, Jérôme Belliard, Paulo Branco, Normand E. Bergeron, Mathieu L. Roy, Diego Tonolla, Nicolas Lamouroux, Hervé Capra, Colden V. BaxterA riverscape approach reveals downstream propagation of stream thermal responses to riparian thinning at multiple scales
Hydrological connectivity in river networks influences their response to environmental changes as local effects may extend downstream via flowing water. For example, localized changes in riparian forest conditions can affect stream temperatures, and these effects may propagate downstream. However, studies evaluating stream temperature responses to riparian forest management have not considered cumAuthorsDavid A. Roon, Jason B. Dunham, Christian E. TorgersenIntegrating regional and local monitoring data and assessment tools to evaluate habitat conditions and inform river restoration
RRestoring degraded rivers requires initial assessment of the fluvial landscape to identify stressors and riverine features that can be enhanced. We associated local-scale river habitat data collected using standardized national monitoring tools with modeled regional water temperature and flow data on mid-sized northwest U.S. rivers (30–60 m wide). We grouped these rivers according to quartiles ofAuthorsFrancine H. Mejia, Jason M Connor, Phil R Kaufmann, Christian E. Torgersen, Eric K Berntsen, Todd AndersenIntegrating thermal infrared stream temperature imagery and spatial stream network models to understand natural spatial thermal variability in streams
Under a warmer future climate, thermal refuges could facilitate the persistence of species relying on cold-water habitat. Often these refuges are small and easily missed or smoothed out by averaging in models. Thermal infrared (TIR) imagery can provide empirical water surface temperatures that capture these features at a high spatial resolution (<1 m) and over tens of kilometers. Our study examineAuthorsMatthew R. Fuller, Joseph L. Ebersole, Naomi Detenbeck, Rochelle Labisoa, Peter Leinenbach, Christian E. TorgersenLand-cover and climatic controls on water temperature, flow permanence, and fragmentation of Great Basin stream networks
The seasonal and inter-annual variability of flow presence and water temperature within headwater streams of the Great Basin of the western United States limit the occurrence and distribution of coldwater fish and other aquatic species. To evaluate changes in flow presence and water temperature during seasonal dry periods, we developed spatial stream network (SSN) models from remotely sensed land-AuthorsAndrew S. Gendaszek, Jason B. Dunham, Christian E. Torgersen, David P Hockman-Wert, Michael Heck, Justin Martin Thorson, Jeffrey Michael Mintz, Todd AllaiNon-USGS Publications**
Torgersen, C.E., Close, D.A., 2004, Influence of habitat heterogeneity on the distribution of larval Pacific lamprey (Lampetra tridentata) at two spatial scales: Freshwater Biology, v. 49, no. 5, p. 614-630.Fausch, K.D., Torgersen, C.E., Baxter, C.V., Li, H.W., 2002, Landscapes to riverscapes- bridging the gap between research and conservation of stream fishes: BioScience, v. 52, no. 6, p. 483-498.Torgersen, C.E., Faux, R.N., McIntosh, B.A., Poage, N., Norton, D.J., 2001, Airborne thermal remote sensing for water temperature assessment in rivers and streams: Remote Sensing of Environment, v. 76, p. 386-398.Torgersen, C.E., Price, D.M., Li, H.W., McIntosh, B.A., 1999, Multiscale thermal refugia and stream habitat associations of chinook salmon in northwestern Oregon: Ecological Applications, v. 9, no. 1, p. 301-319, https://doi.org/10.1890/1051-0761(1999)009[0301:MTRASH]2.0.CO;2.Torgersen, C.E., Poage, N., Flood, M., Norton, D.J., McIntosh, B.A., 1996, Airborne thermal remote sensing of salmonid habitat for restoration planning in Pacific Northwestern watersheds, Baltimore, MD In eds., Proceedings of the Watershed 96 Conference: Alexandria, VA, Water Environment Federation, p. 812-814.Poage, N., Torgersen, C.E., Norton, D.J., Flood, M., McIntosh, B.A., 1996, Application of thermal infrared (FLIR) and visible videography to the monitoring and restoration of salmonid habitat in the Pacific Northwest In Greer, J.D., ed., Proceedings of the Sixth Forest Service Remote Sensing Applications Conference: Denver, CO, American Society for Photogrammetry and Remote Sensing, p. 376-379.Torgersen, C.E., Jones, J.A., Moldenke, A.R., LeMaster, M.P., 1995, The spatial heterogeneity of soil invertebrates and edaphic properties in an old growth forest stand in western Oregon In Collins, H.P., Robertson, G.P., Klug, M.J., eds., The Significance and Regulation of Soil Biodiversity: Dordrecht, Netherlands, Kluwer Academic Publishers, p. 225-236.Torgersen, C.E., Price, D.M., Li, H.W., McIntosh, B.A., 1995, Thermal refugia and chinook salmon habitat in Oregon- Applications of airborne thermal videography In Mausel, P., ed., Proceedings of the 15th Biennial Workshop on Color Photography and Videography: Terre Haute, IN, American Society for Photogrammetry and Remote Sensing, p. 167-171.Torgersen, C.E., Baxter, C.V., Li, H., McIntosh, B.A., 2006, Landscape influences on longitudinal patterns of river fishes- Spatially continuous analysis of fish-habitat relationships In Hughes, R., Wang, L., Wofford, J.E., eds., Influences of Landscapes on Stream Habitats and Biological Assemblages: Bethesda, MD, American Fisheries Society, p. 473-492**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
- News
To request an interview, contact fresc_outreach@usgs.gov or call (541) 750-1030.