These data provide a comprehensive survey of peak-stage indicators along the Colorado River corridor between river mile (RM) 0 and RM 87 (see Figure 1 in the associated USGS-SIR). In 2008, the locations of peak-stage indicators in three short reaches downstream from RM 87 were measured using a handheld GPS unit (see Appendix 1 in the associated USGS-SIR). Total-station measurements were made using an established network of survey control that references the 2011 realization of NAD83 (NAD83 (2011)) (Kaplinski and others, 2017). The measurements were projected into the State Plane Coordinate System of 1983, Arizona central zone (FIPS zone 0202). Vertical positions are provided in both NAD83 ellipsoid heights and in NAVD88 orthometric elevations modeled from GEOID12b.

These data were compiled for monitoring riparian vegetation change along the Colorado River. This file contains data recorded at 42 sandbars between Lees Ferry and Diamond Creek, AZ, which are sampled for both geomorphic and vegetation change annually. Field data contained here were collected from 2012 to 2016 in September and October of each year. Plant species cover values in 5441 1m^2 quadrat frames, locations and elevations of those sampling frames, slope and aspect, sample dates, temperature and precipitation data, and flood frequency parameters were either recorded in the field or calculated. Annual and seasonal climate variables were estimated from eight weather stations distributed along the river corridor from data aquired from Caster et al. 2014. Data collected between 1 February 2008 and 31 January 2011 were used, as the greatest number of weather stations were recording data with the fewest data gaps during this time. Data were linearly interpolated to sandbars lacking weather data based on distance from adjacent weather stations. Available climate variables included minimum and maximum annual temperature; mean annual, winter (November - April) and monsoon (May - October) precipitation; and mean annual humidity. Inundation and depth to water table were estimated for each plot using plot elevation (acquired from Kaplinski et al. 2014), the 15-minute hydrograph from Glen Canyon Dam (https://www.gcmrc.gov/discharge_qw_sediment/?), and the stage calculator developed for sandbars by Hazel et al. (2006). Discharge data from the 365 days preceding the vegetation surveys were used to calculate the proportion of that year, and the maximum number of contiguous days in which a plot was inundated; minimum, mean and maximum inundation depth; and elevation above river stage at 566m3s-1 (average daily peak flow).

These data were compiled for monitoring riparian vegetation change along the Colorado River. This file contains data recorded at 42 sandbars between Lees Ferry and Diamond Creek, AZ, which are sampled for both geomorphic and vegetation change annually. Field data contained here were collected from 2012 to 2016 in September and October of each year. Plant species cover values in 5441 1m^2 quadrat frames, locations and elevations of those sampling frames, slope and aspect, sample dates, temperature and precipitation data, and flood frequency parameters were either recorded in the field or calculated. Annual and seasonal climate variables were estimated from eight weather stations distributed along the river corridor from data aquired from Caster et al. 2014. Data collected between 1 February 2008 and 31 January 2011 were used, as the greatest number of weather stations were recording data with the fewest data gaps during this time. Data were linearly interpolated to sandbars lacking weather data based on distance from adjacent weather stations. Available climate variables included minimum and maximum annual temperature; mean annual, winter (November - April) and monsoon (May - October) precipitation; and mean annual humidity. Inundation and depth to water table were estimated for each plot using plot elevation (acquired from Kaplinski et al. 2014), the 15-minute hydrograph from Glen Canyon Dam (https://www.gcmrc.gov/discharge_qw_sediment/?), and the stage calculator developed for sandbars by Hazel et al. (2006). Discharge data from the 365 days preceding the vegetation surveys were used to calculate the proportion of that year, and the maximum number of contiguous days in which a plot was inundated; minimum, mean and maximum inundation depth; and elevation above river stage at 566m3s-1 (average daily peak flow).

The U.S. Geological Survey (USGS), in cooperation with the New Mexico Department of Transportation, estimated the magnitude and frequency of floods corresponding to the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities (AEPs; otherwise known as the 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-year floods, respectively) for 346 selected streamgages in New Mexico and parts of Arizona, Colorado, Oklahoma, Texas, and Utah using data through water year 2020. An updated regional flood skew, -0.145, standard error 0.454, was computed for the study area. Regression equations were developed which can be used to estimate the magnitude and frequency of floods at ungaged locations on unregulated streams in the study area. The methods and results of the study are published in the parent report (Bell and others, 2022, https://doi.org/10.5066/XXXXXXXX). For the 346 selected streamgages, this dataset includes peak-flow (*.pkf) and specification (*.psf), output (*.PRT), and export (*.EXP) files from version 7.3 of USGS PeakFQ software (Veilleux and others, 2014; Flynn and others, 2006). Within PeakFQ software, the Expected Moments Algorithm (EMA) was used to conduct frequency analyses to estimate stream discharges corresponding to the 0.5, 0.2, 0.1, 0.04, 0.02, 0.01, 0.005, and 0.002 AEPs. When appropriate, the updated regional skew was used to weight the at-site skew in the frequency analyses. Results of the frequency analyses were used in generalized least-squares (GLS) regression to generate equations that predict discharges corresponding to selected AEPs at ungaged locations on streams in the study area (Bell and others, 2022).

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.

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.

These data were compiled to assess the status and trends of riparian plant communities along the Colorado River between Glen Canyon Dam and Lake Mead, AZ. Three metrics have been proposed to evaluate the "Riparian Vegetation" goal identified in the Glen Canyon Dam Adaptive Management Program's Long Term Experimental and Management Plan (U.S. Department of Interior, 2016). The three metrics are total living plant cover, the proportion of living cover composed of native species, and native species richness. Current policies for Glen Canyon Dam operations result in three longitudinal bands within the riparian area that are flooded at different frequencies. The band, or hydrologic zone, that is most frequently inundated is referred to here as the “active channel” or “AC.” This includes all areas inundated by releases up to 25,000 cubic feet per second (707 m3/s). The “active floodplain” or “AF” is inundated by high flow experiments and includes areas that are inundated by releases between 25,000 cubic feet per second and 45,000 cubic feet per second (1,274 m3/s). The “inactive floodplain” or “IF” is the area along the river that is inundated by releases over 45,000 cubic feet per second, which is not planned under current policies. The metrics are assessed for each of these hydrologic zones. Data from the Grand Canyon Monitoring and Research Center's riparian vegetation monitoring protocol (Palmquist and others, 2018) can be used to evaluate these metrics, which is what is provided here. In short, 80-100 sample sites are randomly selected each year. These sites include debris fans, eddy sandbars, and channel margins. At each randomly selected sample site, ocular cover estimates of each plant species occurring in 1-m2 quadrats spanning the hydrological zones are recorded, along with an estimate of total living plant cover and associated environmental variables. The first metric, total living plant cover, consists of two pieces of data; plant occurrence (a plant is present in the sample frame) and plant cover (proportion of the sample frame covered with living plants). Cover is represented by both an ordinal cover class (1, 2, 3, 4, 5, 6, etc.) and the midpoint of the cover class value (0.01%, 0.5%, 1%, 5%, 10%, 15%, etc). The proportion of native cover is the sum total of native plant cover divided by the sum total of plant cover (native plus nonnative cover) for a sample frame. Native plant richness is the total number of native species rooted inside a sample frame. The total living plant cover data are available for 2016 through 2023. The native cover and richness data are available for 2014 and 2016 through 2023.

The U.S. Geological Survey, in cooperation with Colorado Springs Utilities, has been collecting topographic data annually since 2012 at 10 study areas along Fountain Creek, Colorado. The 10 study areas are located along Fountain Creek between Colorado Springs and the confluence of Fountain Creek and the Arkansas River in Pueblo. This data release presents topographic survey data, Light Detection and Ranging (lidar) survey data, elevation rasters, and elevation-change rasters collected or generated in 2021 as part of that monitoring effort. Topographic survey points were collected using real-time kinematic Global Navigation Satellite Systems (RTK-GNSS). These point data, along with lidar point clouds, were used to generate 2021 elevation rasters and 2015-21 elevation-change rasters. These survey data and maps provide an annual assessment of the geomorphic changes at each study area.

The U.S. Geological Survey, in cooperation with Colorado Springs Utilities, has been collecting topographic data annually since 2012 at 10 study areas along Fountain Creek, Colorado. The 10 study areas are located along Fountain Creek between Colorado Springs and the confluence of Fountain Creek and the Arkansas River in Pueblo. This data release presents topographic survey data, Light Detection and Ranging (lidar) survey data, elevation rasters, and elevation-change rasters collected or generated in 2021 as part of that monitoring effort. Topographic survey points were collected using real-time kinematic Global Navigation Satellite Systems (RTK-GNSS). These point data, along with lidar point clouds, were used to generate 2021 elevation rasters and 2015-21 elevation-change rasters. These survey data and maps provide an annual assessment of the geomorphic changes at each study area.

The U.S. Geological Survey, in cooperation with Colorado Springs Utilities, has been collecting topographic data annually since 2012 at 10 study areas along Fountain Creek, Colorado. The 10 study areas are located along Fountain Creek between Colorado Springs and the confluence of Fountain Creek and the Arkansas River in Pueblo. This data release presents topographic survey data, Light Detection and Ranging (lidar) survey data, elevation rasters, and elevation-change rasters collected or generated in 2021 as part of that monitoring effort. Topographic survey points were collected using real-time kinematic Global Navigation Satellite Systems (RTK-GNSS). These point data, along with lidar point clouds, were used to generate 2021 elevation rasters and 2015-21 elevation-change rasters. These survey data and maps provide an annual assessment of the geomorphic changes at each study area.