Dry Conditions in the Tennessee Valley

October 30, 2007

Chuck BachRiver Operations

Outline

• Recap dry conditions

• Explain how we operated the system in response

• Describe impacts on system benefits:

– Navigation

– Flood-damage reduction

– Power supply

– Water quality

– Water supply

– Recreation

Annual reservoir operating cycle

January 1 Reservoirs are drawn to their lowest level to get ready for flood-producing storms.

June 1 The spring fill, which typically begins inmid-March, is complete, and reservoirs are allowed to fill to their highest level. If water is limited, releases are restricted to the amount of water needed to meet reservoir-specific and system-flow requirements.

Labor Day Drawdown restrictions are lifted. Water is released as needed to meet power demands and provide other benefits.

3-day rainfall ending 10-24-07

Key terms

• Tributary vs. main-stem

• Flood guide

• System minimum operating guide (SMOG)

• Balancing guide

Tennessee River System

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

Vo

lum

e (

10

00

ds

f)

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

Flood guide

Flood guide

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

Vo

lum

e (

10

00

ds

f)

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

SMOG

Flood guide

The SMOG is based on the total volume of water in storage in 10 tributary reservoirs: Watauga, South Holston, Cherokee, Douglas, Fontana, Norris, Chatuge, Nottely, Hiwassee, and Blue Ridge.

System Minimum Operating Guide (SMOG)

Chickamauga minimum flow requirements (cfs)

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

Vo

lum

e (

10

00

ds

f)

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

Balancing Guide 1

SMOG

Flood guide

Balancing guide 1

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

Vo

lum

e (

10

00

ds

f)

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

Balancing guide 1

SMOG

Flood guide

Balancing guide 3

Balancing guide 2

Balancing guides 2 and 3

Tributary reservoir balancing

-60

-40

-20

0

20

40

60

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Ru

no

ff (

Pe

rce

nt

of

No

rma

l)

2010

1941

2000

2006

1988

1986

1985

2007

Annual runoff variability (Eastern Valley)

FY 2007 rainfall/runoff comparison (Eastern Valley)

Rainfall for FY2007 totaled 33.1 inches, 16.9 inches below normal (66 percent of normal).

Runoff for FY07 totaled 12.5 inches, 10.4 inches below normal (54 percent of normal).

10

20

30

40

50

60

Inc

he

s

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

Normal Rainfall

Normal Runoff

Observed Rainfall

Observed Runoff

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

Vo

lum

e (

10

00

ds

f)

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

Balancing guide 1

2007 storage

SMOG

Flood guide

Balancing guide 3

Balancing guide 2

Total tributary system storage, 2007

Chickamauga minimum flow requirements (cfs)

Observed average weeklyflows at Chickamauga

June 3–September 30, 2007

Week Ending

Cubicfeet persecond

June 3June 10June 17June 24

July 1July 8

July 15July 22July 29

August 5August 12August 19August 26

September 2September 9

September 16September 23September 30

14,23418,53218,61219,06218,39516,16816,70915,00914,93325,01025,00125,00825,29825,02510,987

8,3408,751

10,288

Mid-September elevations, 2001-2007: Nottely

1750

1752

1754

1756

1758

1760

1762

1764

1766

1768

1770

1772

1774

2001 2002 2003 2004 2005 2006 2007

No

tte

ly R

eser

voir

Ele

vati

on

(fe

et)

1757.91758.5

1764.4

1770.9

1771.6

1768.9

1753.2

Mid-September elevations, 2001-2007: Fontana

1677.0

1666.3

1698.0

1688.8

1688.4

1646.7

1680.8

1640

1644

1648

1652

1656

1660

1664

1668

1672

1676

1680

1684

1688

1692

1696

1700

1704

1708

2001 2002 2003 2004 2005 2006 2007

Fo

nta

na

Res

erv

oir

Ele

vati

on

(fe

et)

Mid-September elevations, 2001-2007: Douglas

978.65

969.19

973.84

996.56

974.58

976.87

955.47

940

944

948

952

956

960

964

968

972

976

980

984

988

992

996

1000

2001 2002 2003 2004 2005 2006 2007

Do

ug

las

Res

ervo

ir E

leva

tio

n (

feet

)

Public concerns

• “Why didn’t my reservoir reach full pool this summer?”

• “It rained at my house. Why didn’t the reservoir level go up?”

• “Why is my reservoir lower than the other reservoirs in my area?”

Drought impacts

• Navigation

• Flood-damage reduction

• Power supply

• Water quality

• Water supply

• Recreation

Temperatures Precipitation

NOAA three-month outlook

Reservoir operating strategy

Dry conditions continue:

• Maintain minimum flows; conserve any additional water

• Balance tributary reservoir levels

Rain returns:

• Bring tributary reservoirs up to flood-guide levels

• Balance tributary reservoir levels

Spreading the Message

• Conservation operations since February

• Exceptional drought

• Minimum flow requirements continue

• Hold rain/runoff as available

• Beware the reservoir comparison!

BACK-UP SLIDES

Kentucky minimum flow requirements,October 1–September 30

• 5000 cfs year round (instantaneous)

• 12000 cfs October 1–April 30 (daily)

• 15000 cfs May 1–May 31 (bi-weekly)

• 18000 cfs June 1–August 31 (bi-weekly)

• 15000 cfs September 1–September 30 (bi-weekly)

Note: Bi-weekly is defined as any 14-day rolling period.

Tributary reservoir elevations (feet)

-14.6

-23.8

-18.7

-25.7

-33.1

-52.1

-32.2

-27.3

-7.6

-16.1

0.39

0.39

0.41

0.39

0.37

0.36

0.36

0.35

0.38

0.40

1959.0

1729.0

1771.8

1020.0

1512.6

1701.6

991.5

1069.0

1923.3

1682.0

1944.4Watauga

1705.2South Holston

1753.1Nottely

994.3Norris

1479.5Hiwassee

1649.5Fontana

958.3Douglas

1041.7Cherokee

1915.7Chatuge

1665.9Blue Ridge

ReservoirSeptember 1

ElevationFloodGuide Departure

BalancingRatio

Historical comparison (feet)

193219521944.4Watauga

169517081705.2South Holston

174817621753.1Nottely

9851000994.3Norris

147214851479.5Hiwassee

163016531649.5Fontana

945954958.3Douglas

103210451041.7Cherokee

191419181915.7Chatuge

165516681665.9Blue Ridge

ReservoirSeptember 3

Elevation

CurrentWinter

Target Level

Pre-ROSAverage Winter

Level

Normal runoff

2007 runoff

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

Monthly runoff above Chattanooga

200

400

600

800

1000

1200

1400

1600

1800

2000

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

Actual

Budgeted

Latest Forecast

GW

HMonthly hydro generation, FY 2007

Mid-September elevations, 2001-2007: Norris

1007.4

997.1

1009.0

1012.9

1009.0

1007.4

992.4990

992

994

996

998

1000

1002

1004

1006

1008

1010

1012

1014

1016

2001 2002 2003 2004 2005 2006 2007

No

rris

Res

ervo

ir E

leva

tio

n (

feet

)

Mid-September elevations, 2001-2007: Cherokee

1055.7

1046.8

1059.5

1064.4

1054.7

1057.5

1042.0

1038

1040

1042

1044

1046

1048

1050

1052

1054

1056

1058

1060

1062

1064

1066

2001 2002 2003 2004 2005 2006 2007

Ch

ero

kee

Re

serv

oir

Ele

vati

on

(fe

et)

Mid-September elevations, 2001-2007: Hiwassee

1505.1

1503.9

1506.7

1511.7

1507.5 1507.1

1479.01476

1480

1484

1488

1492

1496

1500

1504

1508

1512

1516

1520

2001 2002 2003 2004 2005 2006 2007

Hiw

asse

e R

eser

voir

Ele

vati

on

(fe

et)

Mid-September elevations, 2001-2007: Watauga

1945.1

1942.4

1950.2

1960.6

1952.6

1950.5

1944.0

1940

1942

1944

1946

1948

1950

1952

1954

1956

1958

1960

1962

1964

2001 2002 2003 2004 2005 2006 2007

Wat

aug

a R

eser

voir

Ele

vati

on

(fe

et)

Mid-September elevations, 2001-2007: South Holston

1717.7

1708.8

1719.5

1722.7

1716.4

1720.4

1699.5

1694

1698

1702

1706

1710

1714

1718

1722

1726

2001 2002 2003 2004 2005 2006 2007

So

uth

Ho

lsto

n R

eser

voir

Ele

vat

ion

(fe

et)

Mid-September elevations, 2001-2007: Chatuge

1918.1

1916.8

1920.7

1924.5

1921.8

1921.0

1915.1

1910

1912

1914

1916

1918

1920

1922

1924

1926

1928

1930

2001 2002 2003 2004 2005 2006 2007

Ch

atu

ge

Res

erv

oir

Ele

vati

on

(fe

et)

Mid-September elevations, 2001-2007: Blue Ridge

1671.0 1671.2

1653.0

1682.5

1675.91675.2

1664.4

1650

1654

1658

1662

1666

1670

1674

1678

1682

1686

1690

2001 2002 2003 2004 2005 2006 2007

Blu

e R

idg

e R

eser

voir

Ele

vati

on

(fe

et)