Science for a Changing River
The USGS is collecting continuous and discrete monitoring data to document baseline conditions and physical responses in downstream river reaches before, during, and after dam removal. These monitoring data will be integral for post-removal assessments and collaborations with basin partners.
The world's largest dam removal is underway along the mainstem Klamath River. Dam removal aims to restore threatened and endangered salmon fisheries, the economy, and the way of life of local communities and Indigenous Tribes, especially the Yurok and Karuk, who depend on those fisheries.
The Klamath River Basin has undergone substantial physical changes over the past 150 years. Human impacts include the construction and operation of hydroelectric dams, loss of extensive wetlands, water diversions for agricultural uses, mining operations, road construction, and timber harvesting. The operation of hydroelectric dams and reservoirs heavily altered natural flows and water quality in the Klamath River. Diversions and discharges associated with irrigated agriculture in the upper Klamath River have also affected the natural variability of downstream flows and water quality.
Sediment & Dam Removal
USGS Klamath Dam Removal Studies are focused on tracking a large pulse of fine sediment through the downstream coarse-grained river corridor. The sediment supply is an essential component of a healthy river ecosystem that can affect light penetration, which in turn impacts algae growth and fish feeding success. A common concern surrounding dam removals is the perception that reservoir sediment releases will overwhelm existing sediment processes in downstream river reaches. Typically, there is also much uncertainty about alterations to sediment processes during and following dam removal Foley et al, 2017; Tullos et al, 2016. The removal of four hydroelectric facilities on the mainstem Klamath River was planned with these issues in mind. The timing and sequencing of the removals were planned to minimize downstream impacts. The reservoirs contain approximately 15.5 million cubic yards of primarily fine-grained sediment (84% silt and clay), and approximately 36-57% of this volume is expected to be exported to downstream river reaches (FERC, 2022). The release of reservoir sediments is expected to produce very high suspended-sediment concentrations (7,000 to 14,000 mg/L) for several months during dam removal and relatively high concentrations during the 2nd year following dam removal. In successive years, the suspended sediment concentrations are expected to decline and approach an equilibrium condition as remaining reservoir sediments are stabilized in place and sediments released downstream are exported to the ocean (Reclamation, 2011)/
This Study Addresses Four Key Questions
1. How will suspended sediment transport change?
In collaboration with the Yurok and Karuk Tribes, six continuous monitoring stations were established to measure suspended sediment transport using turbidity as a surrogate measurement. Suspended-sediment transport before, during, and after dam removal will be computed, and changes in transport will be calculated.
2. How will the riparian geomorphology and vegetation change?
Using remote-sensing methods (LiDAR, sonar, UAS imagery, underwater imagery), a geospatial framework was developed to facilitate collaboration with basin partners and assess the river's physical response to dam removal. Repeat monitoring sites are distributed longitudinally along the mainstem river corridor downstream. Baseline geomorphic (Curtis and Bentham, 2022) and riparian land cover (Byrd et al., 2023) maps have been completed. Repeat mapping will be completed during and following dam removal to detect changes in surface roughness, bed sediment textures, and vegetation caused by scour or deposition of reservoir sediment.
3. Can reservoir sediment be distinguished from background sediment?
Three independent methods will be used to distinguish reservoir sediment from background river sediments. A sediment fingerprinting approach will be used to establish diagnostic chemical properties (tracers) for bed sediments collected in tributary channels and reservoirs. Diatoms will be used as a second tracer. During and following dam removal, the relative abundance of reservoir species (planktonic) and river species (benthic) in bed sediment samples collected in downstream river reaches will be used to determine the relative abundance of reservoir and background sediments. A multivariate statistical analysis will be used to detect changes in the relative contribution of reservoir and background sediments. Changes in trace metals in macroinvertebrates and bed sediments will also be assessed through repeat sampling.
4. How will bed textures in the estuary change?
In collaboration with the Yurok Tribe, bed sediments were collected throughout the Klamath Estuary to establish baseline grain sizes. Boat-based samples were collected using a USGS BMH-60 bed material sampler, and grab samples were collected by hand in shallow areas to document surficial sediment characteristics (East et al., 2023). Repeat sampling during and following dam removal will be used to detect changes in bed texture caused by fine sediment deposition.
Effects of Dam Removal on Suspended-Sediment Transport & Geomorphology
The USGS is collecting monitoring data to assess the effects of dam removal on suspended sediment transport and the geomorphology of the downstream river reaches. To assess the effects of dam removal on suspended sediment transport, the USGS will compute the amount of sediment transported before, during, and after dam removal at six monitoring gages distributed longitudinally along the mainstem Klamath River. In key sub-reaches, the USGS will conduct detailed topographic and bathymetric mapping, process-related studies to assess changes in geomorphology and riparian vegetation, and assessments of metal concentrations in benthic macroinvertebrates and bed material sampling before and after dam removal to detect changes
Effects of Dam Construction on Salmon
The construction of four hydroelectric dams between 1922 and 1965 was one of the most significant ecosystem disturbances in the basin. Currently, the dams block access to 420 miles of salmon habitat in the upper basin. Many upper basin streams are groundwater-fed and historically provided critical cold-water refugia. The reservoirs above the dams negatively affect downstream water temperatures and dissolved oxygen concentrations. Annual toxin-producing harmful algal (cyanobacteria) blooms threaten the health of humans and the ecosystem. Since 2005, the growth of toxic algae (Microcystis) in the Copco No. 1 and Iron Gate reservoirs has resulted in annual health advisories for swimmers, boaters, and recreational users. The health warnings commonly recommend avoiding direct water contact and often extend from the reach containing the reservoirs to the river’s estuary. The presence and operation of the dams altered flow regimes and sediment transport processes by disrupting the sediment supply and altering the timing, magnitude, and duration of peak flows (Reclamation, 2011). Adverse effects related to the presence and operation of the dam also impacted downstream spawning and rearing habitats and contributed to devastating levels of disease and salmon mortality (NRC, 2004). Reductions in salmon stocks and the perpetuation of algal toxins in the lower river also negatively affect the health and cultural vitality of the Indigenous Tribes.
Effects of Dam Removal on Ecological Flows and Fish Disease
Removed dams affect the downstream ecosystem by blocking access to 420 miles of cold-water habitat in the upper basin and altering streamflow and sediment transport in the lower basin. A lack of scouring flows and poor water quality are key factors that led to the proliferation of a worm, the host for a parasite known to cause mortality in juvenile and adult salmon. Before dam removal, managed flow releases were implemented to disturb the worms' preferred habitat, disrupt the parasites' life cycle, and decrease the presence of the parasites that cause fish disease..
Linking Dam Removal to Water Availability in the Klamath Basin
Because anticipated changes in water quality, sediment transport, and geomorphology during and following dam removal depend on water availability, dam removal is expected to affect water management in the upper Klamath River basin. For this reason, the physical response of the river and the impacts of dam removal on the downstream river corridor are inextricably linked to water availability and water management in the upper basin.
Relevance and Benefits
The Klamath Basin is important to many stakeholders, including several Indigenous Tribes, the U.S. Department of the Interior, the States of Oregon and California, agricultural communities, counties, and non-profit groups. Anticipated benefits of dam removal include volitional fish passage and increases in cold-water habitat for endangered salmon, free-flowing river channel through the former hydroelectric reach, and more naturally dynamic sediment transport and flow conditions in downstream reaches of the mainstem Klamath River.
References
Byrd, K.B., Hartley, S.H., Poitras, T., and Curtis, J.A., 2022, Baseline High Resolution Land Cover Map for the Mainstem Klamath River Corridor Downstream of Iron Gate Dam, Klamath River, CA, 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9YT80J4.
Curtis, J.A., and Benthem, A.J., 2022, Baseline geomorphic map and land-surface parameters, derived from integrated topobathymetric elevation data, for the mainstem Klamath River corridor downstream of Iron Gate Dam, CA, 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P90KEKPH.
East, A.E., Anderson, C.W., Curtis, J.A., Haught, D.R.W., and Wright, S.A., 2023, Sediment grain-size data from the Klamath estuary, California: U.S. Geological Survey data release, https://doi.org/10.5066/P9MAJHNI
Federal Energy Regulatory Commission, 2022, Final Environmental Impact Statement for Hydropower License Surrender and Decommissioning, Federal Energy Regulatory Commission Office of Energy Projects, https://elibrary.ferc.gov/eLibrary/filelist?accession_number=20220826-3006
Foley, M.M., Bellmore, J.R., O'Connor, J.E., Duda, J.J., East, A.E., Grant, G.E., Anderson, C.W., Bountry, J.A., Collins, M.J., Connolly, P.J., Craig, L.S., Evans, J.E., Greene, S.L., Magilligan, F.J., Magirl, C.S., Major, J.J., Pess, G.R., Randle, T.J., Shafroth, P.B., Torgersen, C.E., Tullos, D., and Wilcox, A.C., 2017, Dam removal: Listening in: Water Resources Research, v. 53, no. 7, p. 5229-5246, doi: 10.1002/2017WR020457, https://dx.doi.org/10.1002/2017WR020457
National Research Council, 2004, Endangered and threatened fishes in the Klamath River Basin—Causes of decline and strategies for recovery: Washington, DC, The National Academies Press, https://doi.org/10.17226/10838
U.S. Bureau of Reclamation, 2011. Hydrology, Hydraulics and Sediment Transport Studies for the Secretary’s Determination on Klamath River Dam Removal and Basin Restoration,” Technical Report No. SRH-2011-02. Prepared for Mid-Pacific Region, US Bureau of Reclamation, Technical Service Center, Denver, CO. https://www.fws.gov/sites/default/files/documents/Full%20SDOR%20accessible%20022216.pdf
Tullos, D.D., Collins, M.J., Bellmore, J.R., Bountry, J.A., Connolly, P.J., Shafroth, P.B. and Wilcox, A.C., 2016. Synthesis of common management concerns associated with dam removal. JAWRA Journal of the American Water Resources Association, 52(5), pp.1179-1206. https://doi.org/10.1111/1752-1688.12450
Upper Klamath Basin Studies and Data Collection
Sediment Mobility and Riparian Corridor Assessment, Klamath River, CA
Sediment Fingerprinting in the Upper Klamath Basin
Nutrient and Sediment Loading to Upper Klamath Lake
The USGS is collecting continuous and discrete monitoring data to document baseline conditions and physical responses in downstream river reaches before, during, and after dam removal. These monitoring data will be integral for post-removal assessments and collaborations with basin partners.
The world's largest dam removal is underway along the mainstem Klamath River. Dam removal aims to restore threatened and endangered salmon fisheries, the economy, and the way of life of local communities and Indigenous Tribes, especially the Yurok and Karuk, who depend on those fisheries.
The Klamath River Basin has undergone substantial physical changes over the past 150 years. Human impacts include the construction and operation of hydroelectric dams, loss of extensive wetlands, water diversions for agricultural uses, mining operations, road construction, and timber harvesting. The operation of hydroelectric dams and reservoirs heavily altered natural flows and water quality in the Klamath River. Diversions and discharges associated with irrigated agriculture in the upper Klamath River have also affected the natural variability of downstream flows and water quality.
Sediment & Dam Removal
USGS Klamath Dam Removal Studies are focused on tracking a large pulse of fine sediment through the downstream coarse-grained river corridor. The sediment supply is an essential component of a healthy river ecosystem that can affect light penetration, which in turn impacts algae growth and fish feeding success. A common concern surrounding dam removals is the perception that reservoir sediment releases will overwhelm existing sediment processes in downstream river reaches. Typically, there is also much uncertainty about alterations to sediment processes during and following dam removal Foley et al, 2017; Tullos et al, 2016. The removal of four hydroelectric facilities on the mainstem Klamath River was planned with these issues in mind. The timing and sequencing of the removals were planned to minimize downstream impacts. The reservoirs contain approximately 15.5 million cubic yards of primarily fine-grained sediment (84% silt and clay), and approximately 36-57% of this volume is expected to be exported to downstream river reaches (FERC, 2022). The release of reservoir sediments is expected to produce very high suspended-sediment concentrations (7,000 to 14,000 mg/L) for several months during dam removal and relatively high concentrations during the 2nd year following dam removal. In successive years, the suspended sediment concentrations are expected to decline and approach an equilibrium condition as remaining reservoir sediments are stabilized in place and sediments released downstream are exported to the ocean (Reclamation, 2011)/
This Study Addresses Four Key Questions
1. How will suspended sediment transport change?
In collaboration with the Yurok and Karuk Tribes, six continuous monitoring stations were established to measure suspended sediment transport using turbidity as a surrogate measurement. Suspended-sediment transport before, during, and after dam removal will be computed, and changes in transport will be calculated.
2. How will the riparian geomorphology and vegetation change?
Using remote-sensing methods (LiDAR, sonar, UAS imagery, underwater imagery), a geospatial framework was developed to facilitate collaboration with basin partners and assess the river's physical response to dam removal. Repeat monitoring sites are distributed longitudinally along the mainstem river corridor downstream. Baseline geomorphic (Curtis and Bentham, 2022) and riparian land cover (Byrd et al., 2023) maps have been completed. Repeat mapping will be completed during and following dam removal to detect changes in surface roughness, bed sediment textures, and vegetation caused by scour or deposition of reservoir sediment.
3. Can reservoir sediment be distinguished from background sediment?
Three independent methods will be used to distinguish reservoir sediment from background river sediments. A sediment fingerprinting approach will be used to establish diagnostic chemical properties (tracers) for bed sediments collected in tributary channels and reservoirs. Diatoms will be used as a second tracer. During and following dam removal, the relative abundance of reservoir species (planktonic) and river species (benthic) in bed sediment samples collected in downstream river reaches will be used to determine the relative abundance of reservoir and background sediments. A multivariate statistical analysis will be used to detect changes in the relative contribution of reservoir and background sediments. Changes in trace metals in macroinvertebrates and bed sediments will also be assessed through repeat sampling.
4. How will bed textures in the estuary change?
In collaboration with the Yurok Tribe, bed sediments were collected throughout the Klamath Estuary to establish baseline grain sizes. Boat-based samples were collected using a USGS BMH-60 bed material sampler, and grab samples were collected by hand in shallow areas to document surficial sediment characteristics (East et al., 2023). Repeat sampling during and following dam removal will be used to detect changes in bed texture caused by fine sediment deposition.
Effects of Dam Removal on Suspended-Sediment Transport & Geomorphology
The USGS is collecting monitoring data to assess the effects of dam removal on suspended sediment transport and the geomorphology of the downstream river reaches. To assess the effects of dam removal on suspended sediment transport, the USGS will compute the amount of sediment transported before, during, and after dam removal at six monitoring gages distributed longitudinally along the mainstem Klamath River. In key sub-reaches, the USGS will conduct detailed topographic and bathymetric mapping, process-related studies to assess changes in geomorphology and riparian vegetation, and assessments of metal concentrations in benthic macroinvertebrates and bed material sampling before and after dam removal to detect changes
Effects of Dam Construction on Salmon
The construction of four hydroelectric dams between 1922 and 1965 was one of the most significant ecosystem disturbances in the basin. Currently, the dams block access to 420 miles of salmon habitat in the upper basin. Many upper basin streams are groundwater-fed and historically provided critical cold-water refugia. The reservoirs above the dams negatively affect downstream water temperatures and dissolved oxygen concentrations. Annual toxin-producing harmful algal (cyanobacteria) blooms threaten the health of humans and the ecosystem. Since 2005, the growth of toxic algae (Microcystis) in the Copco No. 1 and Iron Gate reservoirs has resulted in annual health advisories for swimmers, boaters, and recreational users. The health warnings commonly recommend avoiding direct water contact and often extend from the reach containing the reservoirs to the river’s estuary. The presence and operation of the dams altered flow regimes and sediment transport processes by disrupting the sediment supply and altering the timing, magnitude, and duration of peak flows (Reclamation, 2011). Adverse effects related to the presence and operation of the dam also impacted downstream spawning and rearing habitats and contributed to devastating levels of disease and salmon mortality (NRC, 2004). Reductions in salmon stocks and the perpetuation of algal toxins in the lower river also negatively affect the health and cultural vitality of the Indigenous Tribes.
Effects of Dam Removal on Ecological Flows and Fish Disease
Removed dams affect the downstream ecosystem by blocking access to 420 miles of cold-water habitat in the upper basin and altering streamflow and sediment transport in the lower basin. A lack of scouring flows and poor water quality are key factors that led to the proliferation of a worm, the host for a parasite known to cause mortality in juvenile and adult salmon. Before dam removal, managed flow releases were implemented to disturb the worms' preferred habitat, disrupt the parasites' life cycle, and decrease the presence of the parasites that cause fish disease..
Linking Dam Removal to Water Availability in the Klamath Basin
Because anticipated changes in water quality, sediment transport, and geomorphology during and following dam removal depend on water availability, dam removal is expected to affect water management in the upper Klamath River basin. For this reason, the physical response of the river and the impacts of dam removal on the downstream river corridor are inextricably linked to water availability and water management in the upper basin.
Relevance and Benefits
The Klamath Basin is important to many stakeholders, including several Indigenous Tribes, the U.S. Department of the Interior, the States of Oregon and California, agricultural communities, counties, and non-profit groups. Anticipated benefits of dam removal include volitional fish passage and increases in cold-water habitat for endangered salmon, free-flowing river channel through the former hydroelectric reach, and more naturally dynamic sediment transport and flow conditions in downstream reaches of the mainstem Klamath River.
References
Byrd, K.B., Hartley, S.H., Poitras, T., and Curtis, J.A., 2022, Baseline High Resolution Land Cover Map for the Mainstem Klamath River Corridor Downstream of Iron Gate Dam, Klamath River, CA, 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P9YT80J4.
Curtis, J.A., and Benthem, A.J., 2022, Baseline geomorphic map and land-surface parameters, derived from integrated topobathymetric elevation data, for the mainstem Klamath River corridor downstream of Iron Gate Dam, CA, 2018: U.S. Geological Survey data release, https://doi.org/10.5066/P90KEKPH.
East, A.E., Anderson, C.W., Curtis, J.A., Haught, D.R.W., and Wright, S.A., 2023, Sediment grain-size data from the Klamath estuary, California: U.S. Geological Survey data release, https://doi.org/10.5066/P9MAJHNI
Federal Energy Regulatory Commission, 2022, Final Environmental Impact Statement for Hydropower License Surrender and Decommissioning, Federal Energy Regulatory Commission Office of Energy Projects, https://elibrary.ferc.gov/eLibrary/filelist?accession_number=20220826-3006
Foley, M.M., Bellmore, J.R., O'Connor, J.E., Duda, J.J., East, A.E., Grant, G.E., Anderson, C.W., Bountry, J.A., Collins, M.J., Connolly, P.J., Craig, L.S., Evans, J.E., Greene, S.L., Magilligan, F.J., Magirl, C.S., Major, J.J., Pess, G.R., Randle, T.J., Shafroth, P.B., Torgersen, C.E., Tullos, D., and Wilcox, A.C., 2017, Dam removal: Listening in: Water Resources Research, v. 53, no. 7, p. 5229-5246, doi: 10.1002/2017WR020457, https://dx.doi.org/10.1002/2017WR020457
National Research Council, 2004, Endangered and threatened fishes in the Klamath River Basin—Causes of decline and strategies for recovery: Washington, DC, The National Academies Press, https://doi.org/10.17226/10838
U.S. Bureau of Reclamation, 2011. Hydrology, Hydraulics and Sediment Transport Studies for the Secretary’s Determination on Klamath River Dam Removal and Basin Restoration,” Technical Report No. SRH-2011-02. Prepared for Mid-Pacific Region, US Bureau of Reclamation, Technical Service Center, Denver, CO. https://www.fws.gov/sites/default/files/documents/Full%20SDOR%20accessible%20022216.pdf
Tullos, D.D., Collins, M.J., Bellmore, J.R., Bountry, J.A., Connolly, P.J., Shafroth, P.B. and Wilcox, A.C., 2016. Synthesis of common management concerns associated with dam removal. JAWRA Journal of the American Water Resources Association, 52(5), pp.1179-1206. https://doi.org/10.1111/1752-1688.12450