These data were compiled from sampling pre-dam flood terraces and sand bar deposits of the Colorado River in Glen Canyon between Glen Canyon Dam and the Paria River confluence. This includes sand deposits from the 2008, 2012, 2013 and 2014 high flow experiments (HFE) in Marble Canyon. Sand sources from these locations were sampled in September/October of 2013 and 2014. Also, samples of suspended sediment from a selection of Paria River flash floods that preceded the 2013 and 2014 high flow experiments were collected. The suspended sediment samples were wet sieved to separate the <63-micron fraction at the Grand Canyon Monitoring and Research Center. A Niton XL3-t 955 portable XRF was used to measure the elemental concentration of half-phi grain size fractions from every sand sample. Samples were tested 3 times, for 90 seconds each, measuring the concentration of seven elements (Fe, Ca, K, Ti, Rb, Sr, and Zr). The average concentration for each element over the three tests is used in all subsequent analyses. MixSIAR Bayesian mixing model using JAGS for Markov Chain Monte Carlo simulation was used to calculate the relative contribution of Paria River- versus Glen Canyon-derived sand in Marble Canyon HFE deposits.

Lake Mead is a large interstate reservoir located in the Mojave Desert of southeastern Nevada and northwestern Arizona. It was impounded in 1935 by the construction of Hoover Dam and is one of a series of multi-purpose reservoirs on the Colorado River. The lake extends 183 km from the mouth of the Grand Canyon to Black Canyon, the site of Hoover Dam, and provides water for residential, commercial, industrial, recreational, and other non-agricultural users in communities across the southwestern United States. Extensive research has been conducted on Lake Mead, but a majority of the studies have involved determining levels of anthropogenic contaminants such as synthetic organic compounds, heavy metals and dissolved ions, furans/dioxins, and nutrient loading in lake water, sediment, and biota (Preissler, et al., 1998; Bevans et al, 1996; Bevans et al., 1998; Covay and Leiker, 1998; LaBounty and Horn, 1997; Paulson, 1981). By contrast, little work has focused on the sediments in the lake and the processes of deposition (Gould, 1951). To address these questions, sidescan-sonar imagery and high-resolution seismic-reflection profiles were collected throughout Lake Mead by the USGS in cooperation with researchers from University of Nevada Las Vegas (UNLV). These data allow a detailed mapping of the surficial geology and the distribution and thickness of sediment that has accumulated in the lake since the completion of Hoover Dam. Results indicate that the accumulation of post-impoundment sediment is primarily restricted to former river and stream beds that are now submerged below the lake while the margins of the lake appear to be devoid of post-impoundment sediment. The sediment cover along the original Colorado River bed is continuous and is typically greater than 10 m thick through much of its length. Sediment thickness in some areas exceeds 35 m while the smaller tributary valleys typically are filled with less than 4 m of sediment. Away from the river beds that are now covered with post-impoundment sediment, pre-impoundment alluvial deposits and rock outcrops are still exposed on the lake floor.

Bathymetric, topographic, and grain-size data were collected in April 2011 along a 27-mi (43.5 – km) reach of the Colorado River in Grand Canyon National Park, Arizona. The study reach begins at river mile 61.1, about 0.6 -mi (1 –km) above the confluence of the Colorado and Little Colorado Rivers and ends at river mile 88.1 at the upstream boundary of the Bright Angel Rapid (Phantom Ranch boat beach). Channel bathymetry was mapped using multibeam and singlebeam echosounders, subaerial topography was mapped using ground-based total-stations, and bed-sediment grain-size data were collected using an underwater digital microscope system. These data were combined to produce digital elevation models, spatially variable estimates of digital elevation model uncertainty, georeferenced grain-size data, and bed-sediment distribution maps. These data were collected by the Southwest Biological Science Center, Grand Canyon Monitoring and Science Center as a component of a larger effort to monitor the status and trends of sand storage along the Colorado River in Grand Canyon National Park. This dataset is the bed sediment classification derived from multibeam sonar surveys.

In 2012, the U.S. Geological Survey (USGS) in cooperation with Colorado Springs Utilities selected 10 study areas along Fountain Creek between Colorado Springs, Colorado and the confluence of Fountain Creek with the Arkansas River for annual geomorphic monitoring. The purpose of this data release is to present topographic survey data, rasters , and sediment size data collected in 2019 as part of that monitoring effort. Topographic survey points were collected using real-time kinematic Global Navigation Satellite Systems (RTK-GNSS). These point data were interpolated in ArcGIS to generate digital elevation maps (2015 and 2019) and elevation-change maps (from 2015 to 2019) at each study area . In 2019, two types of Unmanned Aerial Survey (UAS) datasets were also collected and processed at one of the study areas (study area three): (1) a UAS Light Detection and Ranging (LiDAR) point cloud collected using the Yellowscan Surveyor payload (Velodyne VLP16 puck and Applanix Inertial Measurement Unit [IMU]) flown at 150 feet (ft) above ground level using the DJI Matrice 600 UAS aircraft, and (2) a photogrammetric survey taken with the Sony a6000 camera at 200 ft above ground level with the DJI Matrice 600 UAS aircraft, which produced an ortho image, a point cloud, and raster surface model (DSM). The USGS is investigating the use of UAS for traditional river surveys of topography. Traditionally, ground-surveying procedures are required to get the level of accuracy and data needed for the annual reporting. The use of UAS could have substantial time and cost savings to supplement the procedures currently used to complete the monitoring. In addition to topographic surveys, pebble-count data were collected in the Spring of 2019 to characterize the size of streambed sediment. Pebble-count surveys included four measurements of grain size at each of 25 equally spaced sampling stations along four separate cross sections across the active channel of each study area. Annual topographic and sediment size data are used to asses geomorphic changes at each study area.

Samples of aeolian (wind-transported) sediment were collected between 2003 and 2010 at multiple locations along the Colorado River corridor within Grand Canyon National Park, Arizona. At each site, sediment being actively transported by wind were collected using a set of four vertically stacked passive samplers (Big Spring Number Eight [BSNE] sand traps). Sediment samples were collected from the traps during site visits separated by days to months. Sediment sample weights were analyzed at the U.S. Geological Survey (USGS) Grand Canyon Monitoring and Research Center laboratory in Flagstaff, Arizona. Sediment-sample weights may be used to calculate rates of aeolian sediment transport at each location. The USGS gratefully acknowledges sampling permission granted by Grand Canyon National Park.

In 2019, the U.S. Geological Survey, in cooperation with the Upper Colorado River Wild and Scenic Stakeholder Group, studied the magnitude and recurrence interval of streamflow needed to initiate bed movement of gravel-sized and finer sediment in a segment of the Colorado River in Colorado to better understand sediment movement and its relation to flow regimes of the river. Two stationary hydrophone systems were installed on April 23, 2019 at the above Catamount Bridge stationary hydrophone site (above Catamount Bridge site), and two were installed on April 24, 2019 at the Radium stationary hydrophone site (Radium site). Pebble counts of coarse surface particles (greater than 2 millimeters [mm; 0.00656 foot]) were performed in the wadeable areas adjacent to the stationary hydrophones to provide general estimates of the size of the material that could be mobilized and recorded near the hydrophones. The particle size of the intermediate axis (B-axis) was measured with a gravelometer, and the largest bin size the particle did not pass through (the retaining sieve size) was recorded. Particles smaller than 2 mm (0.00656 foot) were recorded as less than 2 mm (0.00656 foot). Those particle size measurements are presented in this child item.

These topographic/bathymetric digital elevation models (DEMs) were collected and compiled to characterize erosion and deposition in the Colorado River and in an adjacent zone of laterally recirculating flow (eddy) during both average flow conditions and during a controlled flood that occurred in March 2008. The objectives of the study were to measure changes sandbar morphology that occurred during changes in discharge associated with the controlled flood. These data were collected between February 6 and March 31, 2008 in a 1-mile study reach on the Colorado River within Grand Canyon National Park beginning 44.5 miles downstream from Lees Ferry, Arizona. These data were collected by the USGS Grand Canyon Monitoring and Research Center with cooperators from Northern Arizona University and funding provided by the Glen Canyon Dam Adaptive Management Program. All bathymetric data were collected with a multibeam sonar system (Reson Seabat 8124 sonar with TSS MAHRSS reference system for heave, pitch, roll, and heading). Topographic data were collected by conventional total station. These data can be used to study changes in channel morphology associated with changes in streamflow conditions.

These data were compiled to model the area of exposed, bare sand along 168 km of the Colorado River between Glen Canyon Dam and Bright Angel Creek, Arizona. Objective(s) of our study were to develop and validate four models of exposed sand area for the study reach, respectively based on 1) single-day maxiumum river discharge, 2) multiple-day river discharge patterning, 3) field-observed wind velocities, and 4) remote-sensing measured trends in vegetation areas. These data represent biophysical patterns and processes in the study reach; included here are a) daily records of maximum discharge of the Colorado River at Lees Ferry, Arizona, b) river discharge and exposed sand area throughout the study reach, c) scaling factors for bare sand areas by year based on observed vegetation extents present in the study reach, and d) scaling factors for bare sand areas by day based on our models throughout the study reach. These data were collected along the Colorado River in Grand Canyon, extending from Glen Canyon Dam downstream to Bright Angel Creek, Arizona. Data collection spanned 2002-2022. These data were collected by the U.S. Geological Survey, Southwest Biological Science Center, Grand Canyon Monitoring and Research Center via field observation (e.g., micrometeorological stations and terrestrial lidar), and remote sensing methods (e.g., classification of aerial photographs). These data can be used to conduct bare exposed sand area modeling for the study reach presented here, and may also serve as a basis for developing models of exposed bare sand area for other river systems where similar data are available.

Monthly Mean Dissolved-Solids Concentration and Monthly Mean Dissolved-Solids Load Data Flow weighted monthly mean dissolved-solids concentrations (mg/L) data and monthly mean dissolved-solids load data from 1928-2016 were computed by USGS using raw data from the Bureau of Reclamation. These data were computed by USGS for all of the seven sites (listed below). Colorado River above Imperial Dam, AZ-CA, 09429490 (1976-2016) Colorado River at Lees Ferry, AZ, 09380000 (1947-2016) Colorado River at Northern International Boundary, above Morelos Dam, AZ, 09522000 (1961-2016) Colorado River below Hoover Dam, AZ-NV, 09421500 (1948-2016) Colorado River near Cisco, UT, 09180500 (1928-2016) Green River at Green River, UT, 09315000 (1928-2016) San Juan River near Bluff, UT, 09379500 (1929-2016) Monthly mean dissolved-solids concentrations and loads were not calculated for several time periods (listed below) because of insufficient discrete dissolved-solids concentration data: Colorado River below Hoover Dam, AZ-NV, 09421500 (October 1962 - September 1953) Colorado River near Cisco, UT, 09180500 (October 1936 - September 1938 and October 1939 - September 1940) Green River at Green River, UT, 09315000 (October 1936 - September 1938, October 1939 - September 1940, and October 1942 - September 1943) Discrete Dissolved-Solids Concentration Data Discrete dissolved-solids concentrations (mg/L) data and specific conductance (microsiemens/cm) from 1990-2016 were computed using raw data from the Bureau of Reclamation. These data were computed for four sites (listed below). Colorado River above Imperial Dam, AZ-CA, 09429490 (1990-2016), dissolved-solids Colorado River above Imperial Dam, AZ-CA, 09429490 (1993-2016), specific conductance Colorado River below Hoover Dam, AZ-NV, 09421500 (1993-2016), dissolved-solids Colorado River at Northern International Boundary, above Morelos Dam, AZ, 09522000 (2001-2016), dissolved-solids

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.