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This data release comprises nearly three decades of measurements of sandbar topography for monitoring sites along the Colorado River in Grand Canyon National Park and Glen Canyon National Recreation Area. The data were collected to monitor the effects of the operations of Glen Canyon Dam on sandbars, which are also recreational campsites. The data were collected by the US Geological Survey Grand Canyon Monitoring and Research Center in cooperation with Northern Arizona University. Funding for data collection, processing, and reporting has been provided by the Glen Canyon Dam Adaptive Management Program administered by the US Department of the Interior Bureau of Reclamation.
Discharge records and sand extents along the Colorado River between Glen Canyon Dam and Phantom Ranch, Arizona
The data contained in these tables detail the areal extent of exposed sand, in square meters, along the Colorado River between Glen Canyon Dam, Arizona, and Bright Angel Creek, Arizona, within Glen Canyon National Recreation Area and Grand Canyon National Park. Sand exposure areas are provided as a function of Colorado River discharge, as measured at Lees Ferry, Arizona, in increments of 1000 cubic feet per second. Exposed sand extents are subdivided into mapped and unmapped sand areas; at Colorado River discharge; at flows below 8,000 cubic feet per second, the total extent of exposed sand can be estimated as the sum of field-mapped sand and that sand which was unmapped, but estimated to be present across the study...
In the spring of 1996, a nine-day test flood from Glen Canyon Dam involved the deepest and largest hypolimnetic withdrawals from the penstocks and the river outlet works (ROW) since 1986, interacting with ongoing hydrodynamic and stratification patterns to enhance freshening of the hypolimnion of Lake Powell reservoir and its tailwaters. Prior to the test flood, a six-year drought had produced a pronounced meromictic hypolimnion that was weakening from high inflow events in 1993 and 1995. Hypoxia, however, had continued to increase in the deepest portions of the reservoir. Over the course of the test flood, 0.893 km3 were released from the ports located at and below the hypolimnetic chemocline. The increased discharge...
Flow management and fish density regulate salmonid recruitment and adult size in tailwaters across western North America—Data
This data is a compilation of fishery monitoring data collected by state agencies over several decades in tailwaters downriver of dams in Colorado, Utah, Montana, Wyoming, Idaho, New Mexico, Arizona, California, and Oregon. Specifically, the data contained herein is summary data used in four generalized linear mixed models that were developed to assess the biological and hydrologic factors that influence rainbow and brown trout recruitment and adult size in tailwaters across the western United States.