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USGS Arizona Water Science Center to participate in Colorado River Low Flow event

March 10, 2021

Is there really more water at the USGS Lees Ferry gaging station than Glen Canyon Dam is releasing just a few miles upstream? That question is probably a lot more important than you might think.


Photograph showing Glen Canyon Dam in northern Arizona
Glen Canyon Dam, Arizona

Over the years, the gaging station at Lees Ferry has usually shown a slightly higher discharge than Glen Canyon Dam releases. There are a number of reasons that could cause this difference, but before engineers and scientists can look at the causes, the accuracy of the reported discharges needs to be verified. An upcoming “Spring Disturbance Flow” from Glen Canyon Dam is going to give us that opportunity. The dam will release only 4,000 cubic feet per second into the river (the lowest release in decades) for a period of five days, starting on Monday, March 15. The extreme low discharge will allow USGS personnel to accurately define the stage vs discharge relation at our gaging station (USGS Current Conditions for USGS 09380000 COLORADO RIVER AT LEES FERRY, AZ), when the extra water is at a higher percentage than it is at normal flows. It’s likely a once-in-a-lifetime opportunity, and we’re going to make the most of it.

Not only are we going to confirm the stage vs discharge relation at the Lees Ferry gage with multiple measurements over the entire length of the disturbance, but we’re going a step farther. USGS teams are going to measure cross sections starting just below the dam, and measure at sections all the way to the gaging station 15 miles downstream. Potentially, we could identify an area of the river that is gaining water. And that’s not all!

The extreme low stage of the river is going to expose areas that haven’t been seen in decades. We have applied for permits and received approval to fly one of these areas with an Unmanned Aerial Vehicle to collect valuable hydrology and geomorphology data that would have never been possible.

There’s a lot of important data that are going to be collected the week of March 15. Keep your eye on this website for updates. We will also be posting daily updates on our Twitter account (@USGSAZ).

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