Skip to main content
U.S. flag

An official website of the United States government

Discharge records and sand extents along the Colorado River between Glen Canyon Dam and Phantom Ranch, Arizona

February 3, 2021

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 area. At discharges at or above 8,000 cubic feet per second, all unmapped sand is inundated. Cells highlighted in green correspond to inundation extents derived from hydraulic modeling along the Colorado River in Grand Canyon, and linear interpolation was performed to estimate exposed sand extent between these discrete modeling discharges.