The Middle Fork Willamette River Basin encompasses 3,548 square kilometers of western Oregon and drains to the mainstem Willamette River. Fall Creek Basin encompasses 653 square kilometers and drains to the Middle Fork Willamette River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey evaluated geomorphic responses of downstream river corridors to annual drawdowns to streambed at Fall Creek Lake. This study of geomorphic change is focused on the major alluvial channel segments downstream of the U.S. Army Corps of Engineers dams including the lowermost 11.5 km of Fall Creek and 27.3 km of the Middle Fork Willamette River, as well as Fall Creek Lake. GIS layers defining the landforms, cover type, vegetation density, and secondary water type throughout the active channel study area were developed for six time periods: 1936, 2005, 2011, 2012, 2014, and 2016. GIS layers defining the wetted channel centerline throughout the active channel study area were developed for three time periods: 1936, 2005, and 2016. For this study, the active channel was defined as area typically inundated during annual high flows and includes the low-flow channel as well as side channels, and gravel bars. We also include floodplain islands that have a substantial area surrounded by active channel features in the mapping. The datasets were developed by digitizing from aerial photographs. Aerial photographs from 1936 were scanned, rectified, and mosaicked for this project. Digital channel traces were also produced to depict channel conditions along Fall Creek and the Middle Fork Willamette River floodplains from historical surveys. Plan and profile maps from 1926 (USGS, 1927) provide a basis from which to evaluate spatial and temporal changes that may result from multiple factors and place changes such as aggradation related to annual drawdown to streambed at Fall Creek Lake within historical context. GIS layers defining the outline of the 1926 Middle Fork Willamette River from the confluence with the Coast Fork Willamette River to the North Fork of the Middle Fork Willamette River were digitized. See individual FGDC metadata xml files for more information on the specifications, location, attributes and definitions, and processing descriptions.

Since 2008, large-scale restoration programs have been implemented along the Willamette River, Oregon, to address historical losses of floodplain habitats for native fish. For much of the Willamette River floodplain, direct enhancement of floodplain habitats through restoration activities is needed because the underlying hydrologic, geomorphic, and vegetation processes that historically created and sustained complex floodplain habitats have been fundamentally altered by dam construction, bank protection, large wood removal, land conversion, and other influences (for example, Hulse and others, 2002; Wallick and others, 2013). For gravel-bed rivers like the Willamette River, planimetric changes (defined here as geomorphic changes related to horizontal adjustments independent of elevation and that can be observed using aerial photographs and other two-dimensional maps) include changes in channel position, gravel bars, and side channels. Restoration activities likely to cause planimetric changes in channel features include revetment removal, construction of off-channels features, modifications to floodplain topography, and gravel pit enhancements. Repeat planimetric mapping, provides a basis for quantifying channel changes and relating those changes to restoration projects or other natural or anthropogenic influences affecting geomorphic processes. Repeat mapping also can be used to quantify planimetric changes resulting directly from implementation of restoration projects, as well as subsequent geomorphic evolution of those features. In this study, repeat geomorphic mapping was completed for 2018 and 2020 along the lower 6.8 kilometers of the Middle Fork Willamette River (river mile 187.5 to 191.5 on USGS topographic maps) to support an assessment of geomorphic changes resulting from restoration activities implemented from 2014 to 2017. These datasets can be combined with previously published mapping (Keith and Gordon, 2019) in which the lower 11.6 km of Fall Creek and lower 27.3 km of Middle Fork Willamette were mapped for six periods (1936, 2005, 2011, 2012, 2014, and 2016). The 2018 and 2020 mapping was completed in the vicinity of large-scale restoration projects at the Willamette Confluence Preserve where gravel ponds and revetments were modified to improve floodplain habitats. The repeat mapping datasets include GIS layers defining the landforms and water features, as well as the types of cover and vegetation density on landforms, and types of secondary channel features mapped throughout the active channel. For this study, the active channel was defined as area typically inundated during annual high flows and includes the low-flow channel as well as side channels and gravel bars. Floodplain islands that have a substantial area surrounded by active channel features in the mapping were also included.

Since 2008, large-scale restoration programs have been implemented along the Willamette River, Oregon, to address historical losses of floodplain habitats for native fish. For much of the Willamette River floodplain, direct enhancement of floodplain habitats through restoration activities is needed because the underlying hydrologic, geomorphic, and vegetation processes that historically created and sustained complex floodplain habitats have been fundamentally altered by dam construction, bank protection, large wood removal, land conversion, and other influences (for example, Hulse and others, 2002; Wallick and others, 2013). For gravel-bed rivers like the Willamette River, planimetric changes (defined here as geomorphic changes related to horizontal adjustments independent of elevation and that can be observed using aerial photographs and other two-dimensional maps) include changes in channel position, gravel bars, and side channels. Restoration activities likely to cause planimetric changes in channel features include revetment removal, construction of off-channels features, modifications to floodplain topography, and gravel pit enhancements. Repeat planimetric mapping, provides a basis for quantifying channel changes and relating those changes to restoration projects or other natural or anthropogenic influences affecting geomorphic processes. Repeat mapping also can be used to quantify planimetric changes resulting directly from implementation of restoration projects, as well as subsequent geomorphic evolution of those features. In this study, repeat geomorphic mapping was completed for 2018 and 2020 along the lower 6.8 kilometers of the Middle Fork Willamette River (river mile 187.5 to 191.5 on USGS topographic maps) to support an assessment of geomorphic changes resulting from restoration activities implemented from 2014 to 2017. These datasets can be combined with previously published mapping (Keith and Gordon, 2019) in which the lower 11.6 km of Fall Creek and lower 27.3 km of Middle Fork Willamette were mapped for six periods (1936, 2005, 2011, 2012, 2014, and 2016). The 2018 and 2020 mapping was completed in the vicinity of large-scale restoration projects at the Willamette Confluence Preserve where gravel ponds and revetments were modified to improve floodplain habitats. The repeat mapping datasets include GIS layers defining the landforms and water features, as well as the types of cover and vegetation density on landforms, and types of secondary channel features mapped throughout the active channel. For this study, the active channel was defined as area typically inundated during annual high flows and includes the low-flow channel as well as side channels and gravel bars. Floodplain islands that have a substantial area surrounded by active channel features in the mapping were also included.

The Middle Fork Willamette River Basin encompasses 3,548 square kilometers of western Oregon and drains to the mainstem Willamette River. Fall Creek Basin encompasses 653 square kilometers and drains to the Middle Fork Willamette River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey evaluated geomorphic responses to dam operations at Fall Creek Lake in which lake levels are temporarily lowered to streambed each fall or winter to facilitate downstream passage of juvenile spring Chinook salmon. Reservoir erosion during these streambed drawdown operations results in sediment delivery to downstream reaches. This study of geomorphic change is focused on the major alluvial channel segments downstream of the U.S. Army Corps of Engineers dams on Fall Creek and the Middle Fork Willamette River, as well as the 7.36 square kilometers Fall Creek Lake. This mapping, along with analyses of topographic change, were carried out to better understand patterns and processes of erosion within the reservoir that occur during streambed drawdowns and how they may relate to geomorphic changes in downstream reaches. This dataset consists of a single GIS layer defining the reservoir spatial domains, landforms, and substrates within the Fall Creek Lake reservoir. For this study, the reservoir mapping area boundary was defined by elevation, encompassing all landforms within maximum pool elevation of 254 meters (North American Vertical Datum of 1988) and extends about 10 kilometers from Fall Creek Dam upstream to Big Fall Creek Road bridge. The dataset was mainly developed by digitizing from orthophotographs and digital elevation models (DEMs) created from aerial photographs collected in November 2016 and supplemented with lidar data collected in January 2012.

The Middle Fork Willamette River Basin encompasses 3,548 square kilometers of western Oregon and drains to the mainstem Willamette River. Fall Creek Basin encompasses 653 square kilometers and drains to the Middle Fork Willamette River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey evaluated geomorphic responses to dam operations at Fall Creek Lake in which lake levels are temporarily lowered to streambed each fall or winter to facilitate downstream passage of juvenile spring Chinook salmon. Reservoir erosion during these streambed drawdown operations results in sediment delivery to downstream reaches. This study of geomorphic change is focused on the major alluvial channel segments downstream of the U.S. Army Corps of Engineers dams on Fall Creek and the Middle Fork Willamette River, as well as the 7.36 square kilometers Fall Creek Lake. This mapping, along with analyses of topographic change, were carried out to better understand patterns and processes of erosion within the reservoir that occur during streambed drawdowns and how they may relate to geomorphic changes in downstream reaches. This dataset consists of a single GIS layer defining the reservoir spatial domains, landforms, and substrates within the Fall Creek Lake reservoir. For this study, the reservoir mapping area boundary was defined by elevation, encompassing all landforms within maximum pool elevation of 254 meters (North American Vertical Datum of 1988) and extends about 10 kilometers from Fall Creek Dam upstream to Big Fall Creek Road bridge. The dataset was mainly developed by digitizing from orthophotographs and digital elevation models (DEMs) created from aerial photographs collected in November 2016 and supplemented with lidar data collected in January 2012.

In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey evaluated geomorphic conditions within Fern Ridge Lake near Eugene, Oregon, to inform cultural resources management and other natural resources decisions. Reservoir erosion and deposition during seasonal flood-control operations have formed a diverse array of landforms that can impact water storage, aquatic and riparian habitats, cultural resources, and water quality, among other resources. Process-based geomorphic mapping of Fern Ridge Lake provides a basis for evaluating geomorphic processes and patterns of sediment transfer within the reservoir and provides an inventory of landforms from which to evaluate the geomorphic change over time. This documentation describes a shapefile including process domains, landforms, and cover within the reservoir of Fern Ridge Lake. Mapping encompasses all landforms within a 30-square kilometer area upstream from Fern Ridge Dam approximately coinciding with the maximum pool elevation of 373.5 feet (113.8 meters; National Geodetic Vertical Datum of 1929 [NGVD 29]). Fern Ridge Lake includes submerged reaches of Inman Creek, Hannavan Creek, Long Tom River, Coyote Creek, Middle Fork Coyote Creek, West Fork Coyote Creek, and the Amazon Creek Diversion Channel of Amazon Creek. The dataset was mainly developed by digitizing from orthoimagery and digital surface models (DSMs) created from aerial photographs collected in January 2023 (Schwid and others, 2025). Mapping was conducted during seasonal low-pool conditions when reservoir lake levels are lowered to minimum conservation pool level to provide storage for incoming high flows and minimize downstream flooding; these conditions occur routinely each winter, revealing reservoir flood morphology and are referred to as “seasonal drawdowns.” The geomorphic mapping framework for Fern Ridge Lake was adapted from that developed for Fall Creek Lake, Oregon (Keith and Stratton Garvin, 2021; Keith and others, 2024). An associated data report describes the geomorphic mapping framework for the reservoir at Fern Ridge Lake in greater detail and provides mapping unit descriptions including delineation criteria, hypothesized formation processes inferred from remote-sensing datasets, field observations and literature, and descriptions of specific processes sharing each mapping unit during seasonal flood-control drawdown operations.

The Middle Fork Willamette River Basin encompasses 3,548 square kilometers of western Oregon and drains to the mainstem Willamette River. Fall Creek Basin encompasses 653 square kilometers and drains to the Middle Fork Willamette River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey evaluated geomorphic responses of downstream river corridors to annual drawdowns to streambed at Fall Creek Lake. This study of geomorphic change is focused on the major alluvial channel segments downstream of the U.S. Army Corps of Engineers dams including the lowermost 11.5 km of Fall Creek and 27.3 km of the Middle Fork Willamette River, as well as Fall Creek Lake. This dataset is delivered as one excel workbook with two tabs, and associated metadata includes separate entity sections for each workbook tab. These tables document grain-size distributions and sediment depths collected as a part of a study to document the geomorphic responses to the Fall Creek Lake streambed drawdowns. Surficial grain size distributions and fine sediment deposit depths were measured for this study over 2015 through 2017 to support analyses tracking geomorphic change in the reaches downstream of Fall Creek Lake. Particle counts were collected at 6 gravel bars along Fall Creek and the Middle Fork Willamette River in September 2015. Counts were repeated at 5 of those sites and at 5 additional sites along the Middle Fork Willamette River in October 2016. Multiple clay horizon markers were deployed at 10 sites in October 2015. Deposition depths were measured multiple times throughout the year. Clay horizon markers were deployed again at 9 of the 2015 sites plus one additional site in October-November 2016 and, again, measured throughout the year. Sediment measurements are summarized in spreadsheet tables.

The Middle Fork Willamette River Basin encompasses 3,548 square kilometers of western Oregon and drains to the mainstem Willamette River. Fall Creek Basin encompasses 653 square kilometers and drains to the Middle Fork Willamette River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey evaluated geomorphic responses of downstream river corridors to annual drawdowns to streambed at Fall Creek Lake. This study of geomorphic change is focused on the major alluvial channel segments downstream of the U.S. Army Corps of Engineers dams including the lowermost 11.5 km of Fall Creek and 27.3 km of the Middle Fork Willamette River, as well as Fall Creek Lake. This dataset is delivered as one excel workbook with two tabs, and associated metadata includes separate entity sections for each workbook tab. These tables document grain-size distributions and sediment depths collected as a part of a study to document the geomorphic responses to the Fall Creek Lake streambed drawdowns. Surficial grain size distributions and fine sediment deposit depths were measured for this study over 2015 through 2017 to support analyses tracking geomorphic change in the reaches downstream of Fall Creek Lake. Particle counts were collected at 6 gravel bars along Fall Creek and the Middle Fork Willamette River in September 2015. Counts were repeated at 5 of those sites and at 5 additional sites along the Middle Fork Willamette River in October 2016. Multiple clay horizon markers were deployed at 10 sites in October 2015. Deposition depths were measured multiple times throughout the year. Clay horizon markers were deployed again at 9 of the 2015 sites plus one additional site in October-November 2016 and, again, measured throughout the year. Sediment measurements are summarized in spreadsheet tables.

The active channel of the Willamette River in western Oregon is the portion of the floodplain that regularly conveys water and bed-material sediment (typically sand and gravel) on an annual basis (Wallick and others, 2013). The active channel comprises features such as gravel bars, side channels, main channel and alcoves that contribute to the overall diversity of aquatic and floodplain habitats (for example, Hall and others, 2007; Harrison and others, 2011; Williams and others, 2020). Historically, a complex mosaic of active channel features supported a diverse array of fish and wildlife, but over the last 170 years, construction of flood control dams, bank stabilization structures, removal of large wood and conversion of floodplain forests to agriculture and other land uses has resulted in substantial reductions in the complexity and abundance of active channel features (Sedell and Froggatt, 1984; Hulse and others, 2002; Baker and others, 2004; Wallick and others, 2013; Gregory and others, 2019). For gravel-bed rivers like the Willamette River, active channel features such as gravel bars, side channels, and alcoves can be mapped remotely to evaluate the distribution of features along the river or to assess geomorphic changes over time. Digital geomorphic maps of features within the active channel of the Willamette River were developed to document channel conditions between the confluence of the Coast Fork and Middle Fork Willamette Rivers near Springfield (floodplain kilometer [FPKM] 228) and the head of the Newberg pool, where streamflow is backwatered by Willamette Falls, near Dayton (FPKM 80) in 2009 and 2016. This documentation describes the geomorphic mapping for the active channel of the Willamette River floodplain as mapped from aerial photographs acquired in the summer of 2016.

The active channel of the Willamette River in western Oregon is the portion of the floodplain that regularly conveys water and bed-material sediment (typically sand and gravel) on an annual basis (Wallick and others, 2013). The active channel comprises features such as gravel bars, side channels, main channel and alcoves that contribute to the overall diversity of aquatic and floodplain habitats (for example, Hall and others, 2007; Harrison and others, 2011; Williams and others, 2020). Historically, a complex mosaic of active channel features supported a diverse array of fish and wildlife, but over the last 170 years, construction of flood control dams, bank stabilization structures, removal of large wood and conversion of floodplain forests to agriculture and other land uses has resulted in substantial reductions in the complexity and abundance of active channel features (Sedell and Froggatt, 1984; Hulse and others, 2002; Baker and others, 2004; Wallick and others, 2013; Gregory and others, 2019). For gravel-bed rivers like the Willamette River, active channel features such as gravel bars, side channels, and alcoves can be mapped remotely to evaluate the distribution of features along the river or to assess geomorphic changes over time. Digital geomorphic maps of features within the active channel of the Willamette River were developed to document channel conditions between the confluence of the Coast Fork and Middle Fork Willamette Rivers near Springfield (floodplain kilometer [FPKM] 228) and the head of the Newberg pool, where streamflow is backwatered by Willamette Falls, near Dayton (FPKM 80) in 2009 and 2016. This documentation describes the geomorphic mapping for the active channel of the Willamette River floodplain as mapped from aerial photographs acquired in the summer of 2016.