Glen Canyon Dam 

Hydropower Production and 

Value

Status & Trends, 2018

S. Clayton Palmer

CRSP MC

WESTERN AREA POWER ADMINISTRATION 

/ 
Glen Canyon Powerplant

Capacity: 1,320 MW

Energy: 3,978 GWhs (10-year average annual) 
GCD Hydropower Metrics

Electric generation (energy value)

Electric generation (capacity)

Load following capability

• Emissions

Net firming purchases

Hydro-mechanical equipment

Source: GCD AMP Knowledge Assessment – Status and Trends: Hydropower and Energy

 Topics covered in this presentation

/ 
Status and Trends

Recent variables affecting hydropower metrics

• Recent increase in power efficiency (hydropower 

head)

[hydropower head = elevation of Lake Powell – elevation of GCD tailrace]

This effects electrical generation, capacity & net firming 

purchases

• Implementation of LTEMP operating criteria

This effects capacity and load following capability

• Recent trend of declining electrical energy 

prices

This effects electrical energy value & net firming purchases

/ 
Recent Improvement in Power Efficiency

3700 3634
Recent Increase in Lake Powell Elevation

3634

3555 03/14

EOY 17 

Min Power
GCD Hydropower Head

1963 - 2018 

50%

60%

70%

80%

90%

100%

1-Dec-63

1-May-65

1-Oct-66

1-Mar-68

1-Aug-69

1-Jan-71

1-Jun-72

1-Nov-73

1-Apr-75

1-Sep-76

1-Feb-78

1-Jul-79

1-Dec-80

1-May-82

1-Oct-83

1-Mar-85

1-Aug-86

1-Jan-88

1-Jun-89

1-Nov-90

1-Apr-92

1-Sep-93

1-Feb-95

1-Jul-96

1-Dec-97

1-May-99

1-Oct-00

1-Mar-02

1-Aug-03

1-Jan-05

1-Jun-06

1-Nov-07

1-Apr-09

1-Sep-10

1-Feb-12

1-Jul-13

1-Dec-14

1-May-16

1-Oct-17

Percentage of full power head

Jul, 83

Mar, 05

Jul, 11

% of full power head
Improvement in Power Efficiency since 2014

76%

78%

80%

82%

84%

86%

88%

90%

Percentage of full power head

% of full power head
Recent improvements – and WY 18 Projections

78%

80%

82%

84%

86%

88%

90%

Projected

Percent of full power head

% of full power head
The Effect of Power Efficiency on GCD 

Energy Production

Date

Lake Powell 

Elevation 

(ft)

Energy 

production in a 

9.0 maf year

(GWh) 

Percentage of 

production vs 

full powerhead

July, 1983 3,707.40 4,617 101.25%

Mar., 2005 3,555.90 3,378 74.09%

Jan., 2014 3,578.69 3,575 78.39%

Jan., 2018 3,619.38 3,916 85.89%
LTEMP ROD & Operating Criteria

Changes from MLFF

– Maximum downramp: increased from 1,500 

cfs/hr – 2,500 cfs/hr

– Distribution of monthly volume: changed so it 

is based on SLCA/IP FES electrical demand 

– Maximum allowed daily change in release: 

changed so that it is a strict proportional 

relation to monthly volume

– GCD experiments: there will be a greater 

variety & number of operational experiments

/ 
GCD Monthly Water Volume

MLFF vs LTEMP

(8.23 maf year)

 -

 2,000

 4,000

 6,000

 8,000

 10,000

 12,000

 14,000

 16,000

Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep

MLFF LTEMP

Mean daily release (cfs)
Maximum Daily Allowed Change in 

Release: LTEMP; a strict proportion of 

monthly volumes

• MLFF had 3 thresholds based on monthly 

volume: 500 kaf, 600 kaf & 800 kaf

• LTEMP: maximum daily change is

– 10 x monthly volume June – August [ / 1,000]

– 9 x monthly volume Sept. – May [ / 1,000]

– “Cap” is 8,000 cfs change / day

/ 
WY 2018, so far

MONTH VOLUME

(af)

ALLOWED DAILY 

CHANGE

October, 2017 640,000 5,760 cfs

November, 2017 630,000 5,670 cfs

December, 2017 740,000 6,660 cfs

January, 2018 860,000 7,740 cfs

February, 2018 730,000 6,570 cfs
CRSP Generation vs Demand

(data from Jan. 15 preschedule)

0

200

400

600

800

1000

0100 0200 0300 0400 0500 0600 0700 0800 0900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400

Flaming Gorge

Morrow Point

Blue Mesa

Market Sales

purchases

Crystal, Fontenelle Molina

upramp downramp

DEMAND

Glen Canyon

MW

Time of Day
What have we learned about operating 

GCD under LTEMP so far?

1. Allowable daily change based on a proportion of 

monthly volume provides additional flexibility for 

setting monthly volumes and for meeting the daily 

change in energy demand 

2. So far, in WY 18, two of the months had higher daily 

fluctuation allowance than MLFF. Four had a greater 

restriction

3. The 8 k “cap”, was a binding restriction in one month

4. Faster down ramps are often fully utilized. However, 

GCD downramps still do not match the reduction in 

electrical demand at the end of the day

/ 
The Effect of Electrical Prices on GCD 

Economics and Finances

• The economic and financial impact of GCD 

experiments is a function of the market prices of 

electrical power. 

• Impacts are also a function of the difference between 

peak and off-peak prices. The less the difference, the 

less the impact of GCD experiments that constrain 

operations.

• Both prices and the peak/off price differential are 

variable. 

• In recent years, electrical prices have trended lower and 

the peak/off peak price differential is smaller

/ 
Average Wholesale Electrical Prices

2014 – 2017

(ICE Mid C High)

 -

 5

 10

 15

 20

 25

 30

 35

 40

 45

Trade date

5/6/2014

5/28/20146/19/20147/14/2014

8/5/2014

8/27/20149/19/2014

10/13/2014

11/4/201412/2/2014

12/26/2014

1/22/20152/13/20153/10/2015

4/1/2015

4/24/20155/15/2015

6/9/20157/1/2015

7/24/20158/17/2015

9/9/2015

10/1/2015

10/23/201511/17/201512/11/2015

1/4/2016

1/27/20162/19/20163/14/2016

4/6/2016

4/28/20165/20/20166/14/2016

7/8/20168/1/2016

8/23/20169/15/201610/7/2016

10/31/201611/23/201612/19/2016

1/12/2017

2/6/2017

$/MWh
Onpeak/offpeak price difference

(since the California energy crisis)

 $-

 $5.00

 $10.00

 $15.00

 $20.00

 $25.00

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017

O

n

p

e

a

k

o

f

f

p

e

a

k

d

i

f

f
GCD Operational Experiments

Experimental Flow Number Date(s) Estimated Cost

Aerial Photography Steady Flow 9

Once each 

year: 1997 -

2004

$20,000

Low Summer Steady Flows (LSSF) 1 Summer, 

2000 $26,800,000

Habitat Maintenance Flow (HMF) 1 Nov., 1997 $1,000,000

Beach Habitat Beach Flow 

(BHBF) 2

Spring, 

1996,

Fall, 2004

$ -

High Flow Experiment (HFE) 5 Various $4.1 - $2.1 million

Non-native Fish Suppression 

Flows (TSF) 3 Winter, 

2003 - 2005 WY 05 $2.32 million (benefit)

Steady Fall Flows 3 Fall 2009 -

2011 $270 ,000
Net Firming Purchases

• WAPA incurs firming purchases because it has firm 

electrical delivery obligations, while hydrological 

conditions and GCD releases vary considerably 

• Net firming purchases is a financial metric (rather than 

an economic metric)

• Firming purchase expenses are variable. They are a 

function of:

– GCD releases, market rates, power head, other CRSP units

• Firming purchases expenses have been falling because 

of higher hydraulic head and lower purchase prices

/ 
 -

 5

 10

 15

 20

 25

 30

 35

 40

 45

 -

 500,000

 1,000,000

 1,500,000

 2,000,000

 2,500,000

FY 14 FY 15 FY 16 FY 17

Firming Purchase (MWhs) Average rate ($/MWh)

MWhs

FY 14 – FY 17

$/MWh

WAPA Firming Purchase Expense & 

Average Purchases Price by Year
Effect of GCD Maintenance 

February 8, 2018

0

100

200

300

400

500

600

700

800

900

0100 0200 0300 0400 0500 0600 0700 0800 0900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400

FONTENELLE MOLINA DEER CREEK GLEN CANYON FLAMING GORGE

CRYSTAL MORROW POINT BLUE MESA PURCHASES Demand

Firming Purchases

GCD units 1, 3, 7 & 8 

are unavailable

MW
Results & Conclusions 

• Recent improvements in power efficiency have reduced the 

financial impact of GCD operational experiments and have 

reduced WAPA firming purchase expenses. WY 18 forecast 

may indicate a reversal of this trend

• Implementation of LTEMP operating criteria:

 Has improved load-following capability by increasing 

GCD down-ramps. However, changes in electrical demand 

still exceed allowed ramp rates

 Has allowed some additional flexibility in selecting 

monthly release volumes because strict daily fluctuation 

allowances are no longer tied to monthly volume brackets. 

• Recent decline in electrical energy prices have aided in 

reduced WAPA firming purchase expenses and reduced the 

financial impact of GCD operational experiments 

/ 
Questions ?

WESTERN AREA POWER ADMINISTRATION 

/