# Grand Canyon, Colorado River Flows - December and January



## GCPBA (Oct 22, 2009)

*Grand Canyon, Colorado River Flows - December and January*

This is an November 28, 2017 update from Paul Davidson at Glen Canyon Dam.

The release volume from Glen Canyon Dam for December, 2017, will be 740,000 acre-feet. Hourly releases during December, 2017, are anticipated to fluctuate between approximately 7,300 cfs in the nighttime and 14,000 cfs in the daytime.

The anticipated release volume for January, 2018, is 860,000 acre-feet with daily fluctuations between approximately 9,100 cfs in the nighttime and 16,850 cfs in the daytime.

Looking ahead to April.....The operating tier for water year 2018 was established in August 2017 as the Upper Elevation Balancing Tier, with an initial water year release volume of 8.23 maf and the potential for an April 2018 adjustment to equalization or balancing releases. Based on the current forecast, an April adjustment to balancing is projected to occur and Lake Powell is currently projected to release 9.0 maf in water year 2018. This projection will be updated each month throughout the water year. Reclamation will schedule operations at Glen Canyon Dam to achieve as practicably as possible the appropriate total annual release volume by September 30, 2018.

Paul Davidson, Hydraulic Engineer, Glen Canyon Dam

Bureau of Reclamation 125 S. State St. Salt Lake City, UT 84138 Ph: 801-524-3642


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## David L (Feb 13, 2004)

Interesting comment about an April "equalization or balancing" release, whatever that might mean. I'm gonna call Paul and see what he says. I'll write again with it.


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## asleep.at.the.oars (May 6, 2006)

Would be great to get the answer right from the source, but I expect it means that if projected inflow conditions cross the threshold for enough water in Powell, they will release more water into Mead than the compact minimum. So from now until April, they are planning dam releases to target 8.23 maf for the year, but with good snow pack will bump up flows during the summer so that by the end of September they have let 9 maf through. 
Not a huge difference for boaters spread out over 5 months, and separate from a high-flow release done to build beaches. Those are triggered by sediment inflow from the Paria, not Glen Canyon storage volume.


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## David L (Feb 13, 2004)

I spoke with Paul. A special April release or higher releases from April to year end 2018 is not correct. Dang! I wanted it! 

Paul told me that back in August, 2017, they were expecting to have to release 8,230,000 acre-feet (8.23 maf) of water from Powell to Mead. For the beginning of 2018 they are going to release flows as they have been in past years.

An increase to 9.00 maf for 2018 isn't unexpected. Notably, the January to March flows will accommodate that. They don't have to do neither a special higher increase in April nor higher releases anytime from April to December to pick up the extra 0.77 maf.

So, no particularly higher flow in Grand Canyon during 2018 than what we have been getting in recent years. Unless there is enough sediment pileup at the Paria during the year to allow a November high flow to flush it into the Canyon.


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