Basin Hydrology, Operations and 

2017 Hydrograph

Glen Canyon Technical Work Group

April 19-20, 2016
2

Snow Snowpack peaked at 

~94% on April 2th

As of April 14th

~75% of average
3

85%

69%

45%

87%

45%

1 percent of average based on period 1981-2010.

http://www.usbr.gov/uc/water/basin/tc_cr.html

Reservoir

A-J 

Forecast

(KAF)

Percent 

of 

Average1

Fontenelle 565 74%

Flaming Gorge 740 76%

Blue Mesa 515 76%

Navajo 530 72%

Powell 5,300 74%

Basin Storage

As of 

4/13/2016

Upper Basin Storage

April to July 2016 Forecasted Inflow

Issued April 4, 2016
4

* Water Year 2016 forecast: 8.44 maf (78%)
5

Lake Powell 2016 Operating Tier

Upper Elevation Balancing

• Tier was set in August 2015

– Start with 8.23 maf release

• Use April 24-Month Study 

projections of end of water 

year storage to potentially 

adjust

1. Stay with 8.23 maf

2. Balancing: 8.23 - 9.0 maf

3. Equalization: > 8.23 maf
6
7

*Probable 
8

Water Year 2016 projections

Most: 9.0 maf release

Max: 9.0 maf release 

Min: 9.0 maf release 

Current conditions (as of 4/17)

Elevation: 3,591.2 feet

Content: 10.9 maf, 45% Full
9

End of CY 2016 Projection: 

1,078.8 feet (38% full)

(Range 1,078 to 1,080 feet)

End of CY 2017 Projection:

1,074.1 feet (36% full)

(Range 1,058 to 1,109 feet)

Conditions as of 4/13

Elevation: 1,078.6 feet

Content: 9.9 maf, 38% Full
Unit 

Number

Oct 

2015

Nov 

2015

Dec 

2015

Jan 

2016

Feb 

2016

Mar 

2016

Apr 

2016

May 

2016

Jun 

2016

Jul 

2016

Aug 

2016

Sep 

2016

1

2

3

4

5

6

7

8

Units 

Available 6 7 7 7 5 6 5 6 7 7 5

Capacity 

(cfs) 18,400 22,100 22,100 22.100 15,500 15,300 15,300 18,800 22,100 22,100 14,900

Capacity 

(kaf/month) 1,150 1,130 1,280 1,300 950 1,090 970 1,140 1,140 1,310 1,310 930

Max (kaf)

1 -- -- -- -- 700 700 658 700 800 950 900 700

Most (kaf)

2 600 577 857 857 700 700 658 700 800 950 900 700

Min (kaf)

1 -- -- -- -- 700 700 658 700 800 950 900 700

10

Glen Canyon Power Plant Provisional Unit Outage Schedule for Water Year 2016

1 Projected release, based on January 2016 Min and Max Probable 

Inflow Projections and 24-Month Study model runs

2 Projected release, based on February 2016 Most Probable Inflow 

Projections and 24-Month Study model runs

9.0

9.0

9.0

(updated 2-16-2016)

5

22,100

15,300

7
Unit 

Number

Oct 

2016

Nov 

2016

Dec 

2016

Jan 

2017

Feb 

2017

Mar 

2017

Apr 

2017

May 

2017

Jun 

2017

Jul 

2017

Aug 

2017

Sep 

2017

1

2

3

4

5

6

7

8

Units 

Available 6 7 7 7 5 5 7 7 7 7 8 7

Capacity 

(cfs) 18,500 22,100 22,000 15,200 15,000 15,000 22,000 22,000 22,000 22,000 25,600 18,500

Capacity 

(kaf/month) 1,170 1,310 1,380 1,330 870 1,020 1,310 1,350 1,310 1,370 1,570 1,290

Max (kaf)

1 600 600 850 950 800 900 1,000 1,100 1,200 1,400 1,500 1,049

Most (kaf)

2 600 600 800 800 650 650 600 650 800 1,000 1,050 800

Min (kaf)

1 600 600 800 800 600 600 600 600 650 850 900 630

11

Glen Canyon Power Plant Provisional Unit Outage Schedule for Water Year 2017

1 Projected release, based on January 2016 Min and Max Probable 

Inflow Projections and 24-Month Study model runs

2 Projected release, based on February 2016 Most Probable Inflow 

Projections and 24-Month Study model runs

9.0

8.23

11.9

(updated 2-22-2016)
Sand Budget Model Results

• As of 4/18/2016, not enough sediment input to trigger a 

spring 2016 HFE 
Hydrograph

Development 

for Water Year 2017

13
2016 Hydrograph

Annual Release 

Volume June August September

less than 9.0 maf 600 kaf -

650 kaf 800 kaf 600 kaf

9.0 maf –

less than 9.5 maf 800 kaf 900 kaf 700 kaf

9.5 maf –

less than 10 maf 900 kaf 900 kaf 700 kaf

10 maf and greater 900 kaf or 

more

900 kaf or 

more

800 kaf

or more

14
2017 Hydrograph Initial Thoughts

• Start with 2016 Hydrograph

– Target lower August and September releases

– Move water to other equal value months for hydropower 

(Dec/Jan)

– Avoid shifting “extra” water to June (which cools 

temperatures at the mouth of the LCR)

• Consider proposed modifications 
2017 Projected Release Scenarios

Based on January 2016 24-Month Study Inflow Scenarios

Powell Inflow 

Scenario

WY 2017

Release Projection

Probable 

Minimum

Upper Elevation Balancing Tier 

w/ no Projected April shift

8.23 maf release

Most 

Probable

Upper Elevation Balancing Tier 

w/ Projected April shift to Balancing

9.0 maf release

Probable 

Maximum

Upper Elevation Balancing Tier 

w/ Projected April shift to Equalization

11.9 maf release

16
2017 Hydrograph 

Initial Thoughts / Discussions

Annual Release 

Volume June August September

less than 9.0 maf 600 kaf -

650 kaf 800 kaf 600 kaf

9.0 maf –

less than 9.5 maf 800 kaf 900 kaf 700 kaf

9.5 maf –

less than 10 maf 900 kaf 900 kaf 700 kaf

10 maf and greater 900 kaf or 

more

900 kaf or 

more

800 kaf

or more
2017 Possible Hydrograph 

8.23 maf release scenario

18
2017 Proposed Hydrograph 

9.0 maf release scenario

19
2017 Proposed Hydrograph 

11.9 maf release scenario

• Lots of water to move: limited flexibility, minimal difference

20

2017 Possible Hydrograph

(11.9 maf release)
2017 Hydrograph Next Steps

• Consider Feedback from TWG

• Continue to coordinate with DOI-DOE agencies

• Present to AMWG in May for review

• Draft motion to TWG in June

– TWG discuss and make recommendation to AMWG in June

• TWG present recommendation to AMWG in 

August for approval

21
Questions?

Paul Davidson

801-524-3642

PDavidson@usbr.gov

Hydraulic Engineer, Glen Canyon

Reclamation, Upper Colorado Region

Resource Management Division

Water Resources Group