The Cedar River watershed provides two-thirds of the water supply for the greater Seattle metropolitan region, in addition to being home to numerous federally listed salmon species. The City of Seattle, through Seattle Public Utilities (SPU), works closely with the Cedar River Instream Flow Commission (IFC) to adaptively manage flows on the Cedar River. Seattle operates its water management facilities in the Cedar River to meet two primary objectives: delivery of high quality drinking water to its customers in the Seattle metropolitan area and protection of aquatic and riparian habitat in the mainstem Cedar River and Chester Morse Lake. Water management activities also strive to consider flood protection needs, water delivery to Lake Washington/Lake Washington Ship Canal, and hydropower production at the Seattle City Light Cedar Falls Hydroelectric Facility.
To help the City of Seattle manage high-flow releases during periods of heavy precipitation, the USGS is completing a geomorphic study of the Cedar River. In particular, the USGS is working with the IFC and SPU to develop a conceptual model relating Cedar River geomorphology and aquatic ecology.
9722-DZ000- Geomorphic and hydrologic study of peak-flow management on the Cedar River - Competed FY2013
Problem - The Cedar River in western Washington drains a 186 square mile watershed on the western slope of the Cascade Range (figure 1). The upper 123 square miles are reserved as a protected watershed from which the City of Seattle gets part of its public water supply. The infrastructure for the water supply is managed by Seattle Public Utilities (SPU) and a key feature is Chester Morse Reservoir, which holds 37,200 acre-ft of useable capacity at full pool elevation. Water is diverted from the river for municipal water supply at the Landsburg Diversion Dam, located 13.6 miles downstream of Chester Morse Reservoir. Changes to the hydrologic regime from flow regulation related primarily to the management of Chester Morse Reservoir have affected the riparian and aquatic habitat along the Cedar River corridor. Because the river remains a productive area for salmon, trout, and other species, water-resource managers require detailed information on how best to manage high-flow releases during periods of heavy precipitation in order to provide flood protection while mitigating negative impacts on the fish populations and promoting river health.
Objectives - The overall objective of this study is to define the geomorphic framework and riverine habitat of the Cedar River to better understand river response and habitat health to different flood management practices. A key sub-objective is to determine the geomorphic response of the Cedar River to different combinations of flood magnitude and duration as well as to investigate the magnitude of salmonid-redd scour as a function of flood magnitude and duration.
Relevance and Benefits - This study addresses the effects of flooding on important habitat for endangered salmonids. The study contributes to the goals of the USGS strategic science direction “Understanding Ecosystems and Predicting Ecosystem Change,” as identified and described in the Strategic Science Plan of the USGS (U.S. Geological Survey, 2007).
Approach - The broad approach is to use geomorphic and habitat data to determine the relations between geomorphic features and habitat as a function of peak-flow characteristics. River geometry, geomorphic data, and additional habitat data will be collected to create a numerical model that will simulate geomorphic response in a reach of the river. Scour data will be collected to refine the relation between scour and flow and thus improve the model. Finally, the model will be used to evaluate the degree of geomorphic change and scour related to various flow magnitude and duration scenarios.
Below are publications associated with this project.
The timing of scour and fill in a gravel-bedded river measured with buried accelerometers
Geomorphic response to flow regulation and channel and floodplain alteration in the gravel-bedded Cedar River, Washington, USA
Geomorphic and hydrologic study of peak-flow management on the Cedar River, Washington
Below are partners associated with this project.
- Overview
The Cedar River watershed provides two-thirds of the water supply for the greater Seattle metropolitan region, in addition to being home to numerous federally listed salmon species. The City of Seattle, through Seattle Public Utilities (SPU), works closely with the Cedar River Instream Flow Commission (IFC) to adaptively manage flows on the Cedar River. Seattle operates its water management facilities in the Cedar River to meet two primary objectives: delivery of high quality drinking water to its customers in the Seattle metropolitan area and protection of aquatic and riparian habitat in the mainstem Cedar River and Chester Morse Lake. Water management activities also strive to consider flood protection needs, water delivery to Lake Washington/Lake Washington Ship Canal, and hydropower production at the Seattle City Light Cedar Falls Hydroelectric Facility.
To help the City of Seattle manage high-flow releases during periods of heavy precipitation, the USGS is completing a geomorphic study of the Cedar River. In particular, the USGS is working with the IFC and SPU to develop a conceptual model relating Cedar River geomorphology and aquatic ecology.
9722-DZ000- Geomorphic and hydrologic study of peak-flow management on the Cedar River - Competed FY2013
Problem - The Cedar River in western Washington drains a 186 square mile watershed on the western slope of the Cascade Range (figure 1). The upper 123 square miles are reserved as a protected watershed from which the City of Seattle gets part of its public water supply. The infrastructure for the water supply is managed by Seattle Public Utilities (SPU) and a key feature is Chester Morse Reservoir, which holds 37,200 acre-ft of useable capacity at full pool elevation. Water is diverted from the river for municipal water supply at the Landsburg Diversion Dam, located 13.6 miles downstream of Chester Morse Reservoir. Changes to the hydrologic regime from flow regulation related primarily to the management of Chester Morse Reservoir have affected the riparian and aquatic habitat along the Cedar River corridor. Because the river remains a productive area for salmon, trout, and other species, water-resource managers require detailed information on how best to manage high-flow releases during periods of heavy precipitation in order to provide flood protection while mitigating negative impacts on the fish populations and promoting river health.
Objectives - The overall objective of this study is to define the geomorphic framework and riverine habitat of the Cedar River to better understand river response and habitat health to different flood management practices. A key sub-objective is to determine the geomorphic response of the Cedar River to different combinations of flood magnitude and duration as well as to investigate the magnitude of salmonid-redd scour as a function of flood magnitude and duration.
Relevance and Benefits - This study addresses the effects of flooding on important habitat for endangered salmonids. The study contributes to the goals of the USGS strategic science direction “Understanding Ecosystems and Predicting Ecosystem Change,” as identified and described in the Strategic Science Plan of the USGS (U.S. Geological Survey, 2007).
Approach - The broad approach is to use geomorphic and habitat data to determine the relations between geomorphic features and habitat as a function of peak-flow characteristics. River geometry, geomorphic data, and additional habitat data will be collected to create a numerical model that will simulate geomorphic response in a reach of the river. Scour data will be collected to refine the relation between scour and flow and thus improve the model. Finally, the model will be used to evaluate the degree of geomorphic change and scour related to various flow magnitude and duration scenarios.
- Publications
Below are publications associated with this project.
The timing of scour and fill in a gravel-bedded river measured with buried accelerometers
A device that measures the timing of streambed scour and the duration of sediment mobilization at specific depths of a streambed was developed using data-logging accelerometers placed within the gravel substrate of the Cedar River, Washington, USA. Each accelerometer recorded its orientation every 20 min and remained stable until the surrounding gravel matrix mobilized as sediment was transportedAuthorsAndrew S. Gendaszek, Christopher S. Magirl, Christiana R. Czuba, Christopher P. KonradGeomorphic response to flow regulation and channel and floodplain alteration in the gravel-bedded Cedar River, Washington, USA
Decadal- to annual-scale analyses of changes to the fluvial form and processes of the Cedar River in Washington State, USA, reveal the effects of flow regulation, bank stabilization, and log-jam removal on a gravel-bedded river in a temperate climate. During the twentieth century, revetments were built along ~ 60% of the lower Cedar River's length and the 2-year return period flow decreased by 47%AuthorsAndrew S. Gendaszek, Christopher S. Magirl, Christiana R. CzubaGeomorphic and hydrologic study of peak-flow management on the Cedar River, Washington
Assessing the linkages between high-flow events, geomorphic response, and effects on stream ecology is critical to river management. High flows on the gravel-bedded Cedar River in Washington are important to the geomorphic function of the river; however, high flows can deleteriously affect salmon embryos incubating in streambed gravels. A geomorphic analysis of the Cedar River showed evidence of hAuthorsChristopher S. Magirl, Andrew S. Gendaszek, Christiana R. Czuba, Christopher P. Konrad, Mathieu D. Marineau - Partners
Below are partners associated with this project.