Colorado River · Coconino County
Colorado River at Grand Canyon
USGS site 09402500 · Records since 1923
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About this gauge
The USGS gauge near Grand Canyon measures the Colorado River below Glen Canyon Dam as the Lower Basin's defining flow record. Discharge here reflects controlled releases from Lake Powell, not natural runoff.
Day-to-day flow at this gauge is set by USBR's Glen Canyon Dam operations on a schedule keyed to water-delivery commitments and hydropower demand. Sustained shifts in the seasonal release pattern reflect federal operating-tier decisions on the Colorado.
Live discharge values come from USGS WaterServices instantaneous data. Percentile classification follows USGS WaterWatch methodology against more than a century of published record. This gauge does not carry AHPS flood-stage thresholds because the river is fully regulated at this point.