Basin Hydrology, 

Water Years 2018-2019 

Operations 

Glen Canyon Technical Work Gro

October 10, 2018
2

1 Percent of average based on 

https://www.usbr.gov/uc/water/basin/index.html

Reservoir

Observ

Inflow 

(KAF

Fontenelle 997 

Flaming Gorge 1,11

Blue Mesa 238 

Navajo 155 

Powell 2,60

Upper Basin Storage

Observed 2018 Apri

Issued August 

90%

32%

45% 54%

74% Basin Storage As of 

10/9/18
3
Water Year 2019

Projected Operations

4
5

90%

32%

54%

74%

1 Percent of average based on p

https://www.usbr.gov/uc/water/basin/index.html

Reservoir

WY 

Foreca

(KAF

Fontenelle 1,01

Flaming Gorge 1,26

Blue Mesa 725 

Navajo 685 

Powell 7,60

Basin Storage

As of 

10/9/18

Upper Basin Storage

CBRFC Unregulated Inf

Issued October 1

Water Year 2019 Forec

45%
6

June Mid-Month: 2.65 maf (37%)
7

Lake Powell 2019 Operating TieUpper Elevation Balancing

• Tier was set in August 2018

– 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 maf2. Balancing: 8.23 - 9.0 maf3. Equalization: > 8.23 maf
8

April adjustment to 

Balancing releases

April adjust

Equalization 

No April 

Adjustment

Sept 30, 2019 

Elev = 3,577.59
9
10

End of CY 2018 Projection:

3583.65 feet

End of CY 2019 Projection:

3574.39 feet

Water Year 2019 Projections

Sep Most: 9.00 maf release

Aug Min: 8.23 maf release 

Aug Max: 9.00 maf release 

Water Year 20

Sep Most: 7.4

Aug Min: 7.4

Aug Max: 11.9
11

Most Probable End of CY 2018 

Projection: 1,079.2 feet (38% full)

Min/Max Range: 1,079 to 1,080 feet

Most Probable End 

Projection: 1,070.0 f

Min/Max Range: 1,05
Unit 

Number

Oct 

2018

Nov 

2018

Dec 

2018

Jan 

2019

Feb 

2019

Mar 

2019

Apr 

2019

May 

2019

Jun 

2019

Jul 

2019

12345678

Units 

Available 5766 6 6 6 5 88

Capacity 

(cfs) 16,500 23,700 21,900 21,900 21,900 21,900 21,900 18,350 29,200 29.20

Capacity 

(kaf/month) 1,080 1,410 1,240 1,230 1,110 1,260 1,190 1,100 1,630 1,680 

Max (kaf) 1 640 640 720 860 750 800 710 710 750 850 

Most (kaf) 2 640 640 720 860 750 800 710 710 750 850 

Min (kaf) 1 640 640 720 760 680 710 640 630 660 750 

12

Glen Canyon Power Plant Planned Unit Outage Schedule for Water 

1 Projected release, based on Aug 2018 Min and Max Probable 

Inflow Projections and 24-Month Study model runs

2 Projected release, based on Aug 2018 Most Probable Inflow 

Projections and 24-Month Study model runs

(up

Possible HFE
13
14
15
7

89

10111213141516

Temperature, °C

Lake Powell Release Temperature 

Projected Temperature based on Sep 2018 Forecast

Sep 2018 Most Probable Hydrology Aug 2018 Min Probable HydrologyAug 2018 Max Probable Hydrology Monthly average Temp LFMonthly average Temp CRBD

#Projection start date is based on initial conditions (Jan 2018)

Historic Projected

Questions?

Heather Patno

801-524-3883

hpatno@usbr.gov

Hydraulic Engineer, Glen Canyon

Reclamation, UC Power Office

Resource Management Division

Water Management Group
2018 Hydrograph (9.0 MAF)

Month LTEMP Release, (kaf) BOR/WAPA Planne

(kaf)

OCT 640 640

NOV 640 630

DEC 720 740

JAN 860 860

FEB 750 730

MAR 800 800

APR 710 705

MAY 710 705

JUN 750 760

JUL 850 860

AUG 900 900

SEP 670 670

TOTALS
LTEMP Monthly Release Volumes 2

Month 7.00 7.48 8.23 9.00 9.50 10.50 11.00 12.00 OCT 480 480 640 640 640 640 640 640 6NOV 500 500 640 640 640 640 640 640 6DEC 600 600 720 720 720 720 720 720 7JAN 660 720 760 860 920 1040 1100 1230 1FEB 590 640 680 750 810 920 970 1080 1MAR 620 675 710 800 860 970 1030 1150 1APR 550 600 640 710 760 870 920 1020 1MAY 550 600 630 710 760 860 910 1020 1JUN 580 630 660 750 800 910 960 1060 1JUL 650 710 750 850 900 1020 1080 1200 1AUG 700 760 800 900 970 1090 1160 1280 1SEP 520 565 600 670 720 820 870 960 1

MIN & MOST

MAX