20150402-5127(30456255)

DUKE
ENERGY.
April 2, 2015
Via Electronic Filing
Honorable Kimberly D. Bose, Secretary
Federal Energy Regulatory Commission
888 First Street, N.E.
Washington, DC 20426
Re: Keowee - Toxaway Hydroelectric Project (FERC No. 2503 -154)
Notice of Request for Water Quality Certification
Dear Secretary Bose:
Water Strategy & Hydro Licensing
Duke Energy
526 S. Church Street
Charlotte, NC 28202
Mailing Address
EC12Y
P.O. Box 1006
Charlotte, NC 28201 -1006
Duke Energy Carolinas, LLC (Duke Energy) filed a Final Application for New License (License
Application) for the Keowee - Toxaway Hydroelectric Project, FERC No. 2503 (Project) with the
Federal Energy Regulatory Commission (FERC) on August 27, 2014. On February 5, 2015,
FERC issued the Notice of Application Accepted for Filing and Ready for Environmental
Analysis.
On March 31, 2015, Duke Energy filed a request for Water Quality Certification (WQC) with the
South Carolina Department of Health and Environmental Control (SCDHEC). Pursuant to 18
CFR §5.23, Duke Energy herein provides a copy of the request for WQC filed with SCDHEC,
including proof of the date on which SCDHEC received the request.
The majority of the Project is located in South Carolina with a small portion of Lake Jocassee
located in Transylvania County, North Carolina. The North Carolina Department of Environment
and Natural Resources, Division of Water Quality (merged into the Division of Water Resources
in 2013) issued a letter on April 7, 2011, indicating SCDHEC as the sole authority to issue WQC
for the Project. No water release from the Project occurs in North Carolina.
If you have questions or need additional information regarding this filing, please contact Ms.
Jennifer Huff at 980.373.4392 or Jennifer. Huff @duke - energy.com.
Sincerely:
Jeffrey G. Lineberger, P.E.
Director, Water Strategy & Hydro Licensing
Duke Energy
Enclosures: Request for 401 WQC
Proof of receipt

DUKE
ENERGY.
March 31, 2015
Via overnight delivery
Mr. Charles Hightower
South Carolina Department of Health and Environmental Control
Water Quality Division, Bureau of Water
2600 Bull St
Columbia, SC 29201 -1708
Water Strategy & Hydro Licensing
Duke Energy
526 S. Church Street
Charlotte, NC 28202
Mailing Address
EC12Y
P.O. Box 1006
Charlotte, NC 28201 -1006
Subject: Keowee - Toxaway Hydroelectric Project (FERC No. 2503)
Application for Water Quality Certification Pursuant to Section 401 of the
Clean Water Act
Dear Mr. Hightower:
Duke Energy Carolinas, LLC (Duke Energy) herein submits this application for Water Quality
Certification pursuant to Section 401 of the Clean Water Act (401 WQC) for the Keowee-
Toxaway Hydroelectric Project licensed by the Federal Energy Regulatory Commission (FERC)
as FERC Project No. 2503 (Project). The Existing License for the Project expires on August 31,
2016, and Duke Energy is required to obtain a New License from the FERC in order to continue
operating the Project. The federal action of issuing a New License for the Project requires Duke
Energy to seek a 401 WQC from the South Carolina Department of Health and Environmental
Control (SCDHEC) in accordance with the requirements of 18 CFR §5.23(b), unless waived by
SCDHEC.
On August 27, 2014, Duke Energy filed an Application for a New License (License Application)
with the FERC along with a Relicensing Agreement (RA). The RA represents the collective
vision of the 17 signatory parties as to how the Project should be operated during the New
License term. On February 5, 2015, the FERC issued a Notice of Acceptance and Ready for
Environmental Analysis (Notice of REA). Duke Energy is required to submit an application for
401 WQC in accordance with the requirements of the Federal Power Act within 60 days
following the Notice of REA. The subject of this certification is the continued operation of the
Project under a New License to be issued by the FERC that is consistent with the License
Application and applicable sections of the Keowee - Toxaway RA.
Enclosed is a complete application package for the 401 WQC of the Project. The enclosed
application package is intended to provide the information to certify the operation of the Project
will meet applicable water quality standards in accordance with Section 401 of the Clean Water
Act and South Carolina Water Quality Standards.
The enclosed application includes the following:

Mr. Charles Hightower
March 31, 2015
Page 2
• A description of the existing Project and Project operation;
• An overview of the Relicensing Process including studies completed and agreements
negotiated;
• A description of the proposed Project operation and water quality measures;
• A summary of South Carolina Water Quality Criteria; and
• A summary of the assessment of water quantity, water quality, and aquatic and botanical
resources at the Project excerpted from Exhibit E of the License Application.
Duke Energy has provided all the information required by R 61 -101, including the adjacent
landowner information.
Additional Project information can be obtained from the License Application which is enclosed
on a DVD with this application, and on the Project public relicensing website's online library at
http: / /www. duke - energy. com / lakes / keowee - toxaway - relicensing.asp.
If you have questions or need additional information regarding this filing, please contact Ms.
Jennifer Huff at 980.373.4392 or Jennifer. Huff @duke - energy.com.
Sincerely:
�* 9'—Y
Jeffrey G. Lineberger, P.E.
Director, Water Strategy & Hydro Licensing
Duke Energy
Enclosures: Application for 401 Water Quality Certification
Adjacent landowners (CD)
License Application (DVD)
cc w/o enclosures: Erin Owen, SCDHEC
Jennifer Huff, Duke Energy
Keith Finley, Duke Energy
Garry Rice, Duke Energy
John A. Whittaker IV, Winston & Strawn LLP
Kim Ognisty, Winston & Strawn LLP

Keowee - Toxaway Hydroelectric Project
(FERC No. 2503)
Application for Water Quality Certification
Pursuant to Section 401 of the Clean Water Act
(' DUKE
ENERGY
Duke Energy Carolinas, LLC
Charlotte, North Carolina
March 2015
© Duke Energy Carolinas, LLC

(This page intentionally blank)

Keowee - Toxaway Hydroelectric Project
(FERC No. 2503)
Application for Water Quality Certification
Pursuant to Section 401 of the Clean Water Act
Table of Contents
Listof Figures ................................................................................................ ............................... ill
Listof Tables ................................................................................................. ............................... iv
RequiredInformation ...................................................................................... ............................... v
1.0 Introduction ............................................................................................ ............................... 1
2.0 Project Description .................................................................................. ..............................2
2.1 General Project Description .............................................................. ..............................2
2.1.1 Jocassee Development ............................................................... ..............................2
2.1.2 Keowee Development .............................................................. ............................... 6
2.2 South Carolina Water Quality Criteria ............................................ ............................... 9
2.3 Existing Project Operation ............................................................. ...............................
11
2.3.1 Jocassee Development ............................................................ ...............................
11
2.3.2 Keowee Development .............................................................. .............................12
2.4 Existing Agreements that Influence Project Operations .................. .............................12
2.4.1 New Operating Agreement ..................................................... ...............................
12
2.4.2 Keowee - Toxaway Fishery Resources Memorandum of Understanding ...............
13
2.4.3 Low Inflow Protocol .............................................................. ...............................
13
3.0 Overview of FERC Relicensing ........................................................... ...............................
14
3.1 Stakeholder Process ......................................................................... .............................14
3. 1.1 Stakeholder Team ..................................................................... .............................14
3.1.2 Resource Committees ............................................................. ...............................
14
3.1.3 Study Teams ............................................................................. .............................15
3.1.4 Ad Hoc Committees ............................................................... ...............................
15
3.2 Relicensing Studies ........................................................................ ...............................
15
3.3 Relicensing Agreement .................................................................... .............................16
3.4 Proposed Project Operations & Water Quality Resource Measures .............................16
3.4.1 Proposed Project Operations .................................................. ...............................
17
3.4.1.1 Reservoir Level Operating Ranges and Flow Releases under Normal
Conditions..................................................................... ...............................
17
Duke Energy Carolinas, LLC i 401 WQC Application
Keowee - Toxaway Project (FERC No. 2503)

3.4.1.2 Project Operation under Drought Conditions ................ ...............................
18
3.4.1.3 Project Operation during Maintenance and Emergency Conditions............
18
3.4.2 Proposed Water Quality Resource Measures ........................... .............................19
4.0 Assessment of Water Quality, Water Quantity, and Aquatic Resources at the Project......
20
4.1 Water Quality ................................................................................. ...............................
20
4. 1.1 Dissolved Oxygen .................................................................. ...............................
20
4.1.1.1 Keowee Reservoir Water Quality Modeling Study ....... ...............................
21
4.1.1.2 Jocassee Forebay and Tailwater Water Quality Study .... .............................22
4.1.2 Modeled Cumulative Effects .................................................. ...............................
23
4.1.2.1 Modeled Effects of Hypothetical Nutrient Loading Increases .....................
23
4.1.2.2 Modeled Effects of Climate Change Scenarios ............. ...............................
23
4.1.3 Other Water Quality Parameters ............................................ ...............................
24
4.2 Water Quantity ............................................................................... ...............................
24
4.2.1 Operations Modeling ................................................................ .............................25
4.2.2 Project Reservoir Elevations .................................................. ...............................
25
4.2.3 Water Supply ............................................................................ .............................26
4.2.4 Downstream Effects ............................................................... ...............................
27
4.3 Aquatic Resources ......................................................................... ...............................
30
4.3.1 Rare, Threatened, and Endangered Species ........................... ...............................
30
4.3.2 Special and Unique Habitats .................................................. ...............................
30
4.3.2.1 National Wild and Scenic Rivers .................................. ...............................
30
4.3.2.2 National Estuarine Research Reserves .......................... ...............................
30
4.3.2.3 National Ecological Reserves .......................................... .............................30
4.3.2.4 State Scenic Rivers ........................................................ ...............................
30
4.3.3 Fisheries .................................................................................... .............................30
4.3.3.1 Littoral Fish Spawning and Reproduction ..................... ...............................
30
4.3.3.2 Lake Jocassee Pelagic Trout Fishery ............................. ...............................
31
5.0 Conclusion ........................................................................................... ...............................
32
6.0 Literature Cited .................................................................................... ...............................
33
Appendix A: Keowee Hydro Station and J. Strom Thurmond Hydro Station Flow Releases
during Drought Years
Duke Energy Carolinas, LLC ii 401 WQC Application
Keowee - Toxaway Project (FERC No. 2503)

List of Figures
Figure2.1 -1. Project Map ......................................................................... ............................... 3
Figure 2.1 -2. Upper Savannah River Basin Reservoirs ............................ ............................... 4
Figure 2.1 -3. Lake Jocassee Dam, Tailrace, and Spillway Area Facilities Map ..................... 5
Figure 2.1 -4. Lake Keowee Dam and Tailrace Area Facilities and Little River Dam
AreaFacilities Map ............................................................. ............................... 7
Duke Energy Carolinas, LLC iii 401 WQC Application
Keowee - Toxaway Project (FERC No. 2503)

List of Tables
Table 2.1 -1.
Physical Features of the Jocassee and Keowee Developments .......................... 8
Table 2.2 -1.
Designated Use Classifications of Waterbodies within the Jocassee
and Keowee Watersheds located in South Carolina ......... ...............................
10
Table 2.2 -2.
South Carolina Numeric State Water Quality Standards Relevant to
theProject .......................................................................... ...............................
11
Table 3.2 -1.
Keowee - Toxaway Project Relicensing Studies ................ ...............................
16
Table 3.4 -1.
Proposed Normal Maximum and Normal Minimum Elevations for
Lake Jocassee and Lake Keowee ...................................... ...............................
17
Table 4.2 -1.
Current and Proposed Normal Maximum and Normal Minimum
Elevations for Lakes Jocassee and Keowee ...................... ...............................
25
Table 4.2 -2.
Critical Elevations for Lake Jocassee and Lake Keowee .................................
26
Duke Energy Carolinas, LLC iv 401 WQC Application
Keowee - Toxaway Project (FERC No. 2503)

Required Information
Pursuant to S.C. Code Ann. § 48 -1 -30 and 48 -1 -50 of the 1976 code and under the regulations of
R. 61 -101, an application to the South Carolina Department of Health and Environmental
Control for water quality certification pursuant to Section 401 of the Clean Water Act must
contain the following information:
a) The name, address, phone numbers, principal place of business of the applicant and, if
applicable, the name and address of the agent for the applicant.
The name, address, phone number, and principal place of business of the applicant is:
Duke Energy Carolinas, LLC
Attention: Jennifer Huff
Mail Code EC12Y
526 South Church Street (28202)
PO Box 1006
Charlotte, North Carolina 28201 -1006
(980) 373 -4392
The names and addresses of the agents for the applicant are:
Jeffrey G. Lineberger, P.E.
Director, Water Strategy & Hydro
Licensing
Duke Energy
Mail Code EC12Y
526 S. Church Street (28202)
PO Box 1006
Charlotte, NC 28201 -1006
(704) 382 -5942
[e-mail]
Duke Energy Carolinas, LLC
Garry S. Rice
Deputy General Counsel
Duke Energy
Mail Code DEC45A
550 S. Tryon Street
Charlotte, NC 28202
(704) 382 -8111
[e-mail]
v 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

Jennifer Huff
Keowee - Toxaway Relicensing
Project Manager
Duke Energy
Mail Code EC 12Y
526 S. Church Street (28202)
PO Box 1006
Charlotte, NC 28201 -1006
(980) 373 -4392
[e-mail]
John A. Whittaker, IV
Winston & Strawn LLP
1700 K St. N.W.
Washington, DC 20006
(202) 282 -5766
[e-mail]
b) A complete description of the proposed permitted activity, including the location, affected
waterbody(s), purpose, and intent of the project; maps, drawings, and plans sufficient for
review purposes (detailed engineering plans are not required).
The permitted activity is the release of water related to continued operation of two
hydropower electric generating facilities pursuant to a federally issued license.
Remaining required information is provided in the following sections of this application.
c) A description of all proposed activities reasonably associated with the proposed
permitted project either directly or indirectly, including planned or proposed future
development that relate to water quality considerations.
d)
e)
F
The proposed new federally issued operating license addresses all aspects of hydropower
operations including, but not limited to, measures associated with operation of the
reservoirs, construction and management of public recreation facilities, protection of
significant archaeological and historic sites, and coordination with downstream
hydropower operators. Additional information is provided in the following sections of
this application.
A description of the composition, source, and quantity of any material to be dredged or
used as fill and a description of the area to be impacted, including the area of fill in
acres.
No dredging or filling activities are proposed under this application.
The method of dredging or filling and specific plans for disposal and control of dredge
spoils.
Not applicable.
The names and addresses of adjacent property owners.
The names and addresses of property owners located adjacent to the Project Boundary are
provided on the enclosed CD.
Duke Energy Carolinas, LLC vi 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

1.0 Introduction
Duke Energy Carolinas, LLC (Duke Energy) is the owner, operator, and Federal Energy
Regulatory Commission (FERC) Licensee of the Keowee - Toxaway Hydroelectric Project, FERC
Project No. 2503 (Project). The Existing License for the Project expires on August 31, 2016.
Duke Energy is seeking to obtain a New License from the FERC for the continued operation of
the Project. Duke Energy filed a Final License Application (FLA) for the Project with the FERC
on August 27, 2014. The FLA is included on a DVD supplied with this application. The FLA
includes a Relicensing Agreement (RA), a document representing the collective vision of the 17
signatory parties as to how the Project should be operated during the New License term. The RA
is dated September 18, 2013, and was signed in November 2013 after more than four years of
collaboration and negotiation. The RA became effective on December 1, 2013. See Section 3.3
of this Application for additional information about the RA.
Pursuant to Section 401 of the Clean Water Act (CWA), 33 U.S.0 § 1341(a), Duke Energy must
request Water Quality Certification (WQC) from South Carolina', unless the state authority
waives this requirement. In South Carolina, the South Carolina Department of Health and
Environmental Control (SCDHEC) administers WQC pursuant to S.C. Code Ann. § 48 -1 -30 and
48 -1 -50 of the 1976 Code as well as the regulations defined by R.61 -101.
By filing this application, Duke Energy is seeking to obtain WQC from SCDHEC in accordance
with Section 401 of the CWA for the continued operation of the Project under a New License
issued by the FERC. This application is intended to provide the information to certify the
operation of the Project will meet applicable water quality standards in accordance with Section
401 of the CWA and South Carolina Water Quality Standards.
' The majority of the Project is located in South Carolina with a small portion of Lake Jocassee located in
Transylvania County, North Carolina. The North Carolina Department of Environment and Natural Resources,
Division of Water Quality (merged into the Division of Water Resources in 2013) issued a letter on April 7, 2011,
indicating SCDHEC as the sole authority to issue a 401 WQC for the Project. No water release from the Project
occurs in North Carolina.
Duke Energy Carolinas, LLC 1 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

2.0 Project Description
2.1 General Project Description
The 867.6 -MW Keowee - Toxaway Hydroelectric Project is located in Oconee and Pickens
counties, South Carolina with a small portion in Transylvania County, North Carolina. The
Project consists of two developments: the Jocassee Development and Keowee Development.
The Project was designed in the early to mid -1960s with construction commencing in 1968 and
full commercial operation of all hydro units at the Project occurring by 1975. A map showing
the general location of the Jocassee and Keowee Developments is included as Figure 2.1 -1. A
general description of the developments is included below and a summary of Project features is
included in Table 2.1 -1.
The Project is located in the Upper Savannah River Basin on the Keowee and Little rivers.
Upstream of the Project is the Bad Creek Hydroelectric Project (FERC Project No. 2740), also
owned and operated by and licensed to Duke Energy. Downstream of the Project are Hartwell
Lake, Richard B. Russell Lake, and J. Strom Thurmond Lake, all owned and operated by the US
Army Corps of Engineers (USACE) (Figure 2.1 -2).
2.1.1 Jocassee Development
The 710.1 -MW Jocassee Development is the upstream development of the Project. The Jocassee
Development is located on the Keowee River in Oconee and Pickens counties, South Carolina,
with a small portion of the reservoir extending into Transylvania County, North Carolina. The
Jocassee Powerhouse, also known as the Jocassee Pumped Storage Station, is approximately
5.5 miles (mi) northeast of Salem, South Carolina (Figure 2.1 -1). Commercial operation of Units
1 and 2 began in 1973, and commercial operation of Units 3 and 4 began in 1975. The Jocassee
Development releases water directly into Lake Keowee.
The Jocassee Development includes Lake Jocassee, Jocassee Dam, two saddle dikes (designated
1 and 2), two intake structures, water conveyance tunnels, a powerhouse, and a gated spillway
(Figure 2.1 -3). The Jocassee Pumped Storage Station generates electricity by operating four
turbines supplied with water through the two intake structures and tunnels, typically during the
day, and pumps water from Lake Keowee back to Lake Jocassee during low demand periods,
typically at night.
Lake Jocassee also serves as the lower reservoir for the Bad Creek Hydroelectric Project (FERC
Project No. 2740), a pumped storage project (Figure 2.1 -2).
Duke Energy Carolinas, LLC 2 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

Figure 2.1 -1. Project Map
I Hi gh lan
�j`� T ltlsy v is
sa
HorsepassI River •� j
f Tioxawgp River
cS� I
Nan t�A I r...�a4k C/ otit P
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! �sOU
son River
i
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r �� . � •Raoe.f •k, .
a '
N O uu i,..eF' _ y, a_ r J d4so• or s
C L I Resen�air
SO T
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~~ lu Sum T rfryl
Nitj4n,aI ,6re #t
1
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and
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Table Rock State Park
i
P �ck n s
err t �> ,
Lifffe River
�I}wt 7 C
�''"�� a� ✓�tha ' S -r �� I z I l e
1%'A \� }
Keowee Dam L b e r r
and 7rrilrac rea
llarrtr<
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ai
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i
4 123
m n ire r
\
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76 orris.. /I rbul 17
Kentucky
Virginia
Legend
Keowee - Toxaway Relicensing
Tennessee
---Project Boundary =Lake
— County Boundary —J National Forest] Natural Area.
FERC Project No. 2503
i
North Carolina
Stream State Park I Natural Area
US Highway Urban Area
Project Location Map
j
I
South Carolina '
abamai Georgia
IJ
x
Project Location
= 2 4 6 6 Data Source' Dam data derived from ESRI 93 Base Data Layers, 2003.
Miles Projection: NAD 1933 StatePlane South Carolina International Feet
Duke Energy Carolinas, LLC 3 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

Figure 2.1 -2. Upper Savannah River Basin Reservoirs
Lake Jcssee
Bad Creels Reservoir d
•'a�ilii ai'r
7M,
r. -
M ,L
FHarnwelr La
1'tFatl Na. i4 `ff i11 ir.l. 11.1.. II
5 South Carolir-3
ti
y:4 I +s
JJI
Georgia �
t�
r
t^
Richard B. Russel; Lake
rr
2k
f
AW
.2+
11 �4e
"�1 •iu.dl Y�{'il �Ya�J.✓fIi, YYYBl.:r S1l it. rrFra, M.l lliDix'�afl •aiY1fY }!i Y1 "- r
Duke Energy Carolinas, LLC 4 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

2k
I
qr �4 \
} M r
Tennessee
j south
y11 Carolina
Georgia
Alabama $r
Map Location.
to -
Legend
North ___ Project Boundary
Carolina
Access Roads
-- River Mile
LaAe
I
f'�
Mf �+rJ
.r'
rti
Keowee - Toxaway Relicensing
FERC Project No. 2503
Lake Jocassee Dam, Tailrace
and Spillway Area Facilities Map
a o.zs o.s 9.75
Os6e Source: ESR12OD9, (http',Oo[oercg— Ine.oxrn ps:'rbrld Imagery)
Miles Prgedon: NAD 1693 5!atePlane South Caroline IMerna ionat Feet
Duke Energy Carolinas, LLC 5 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

2.1.2 Keowee Development
The 157.5 -MW Keowee Development is located on the Keowee and Little rivers in Oconee and
Pickens counties, South Carolina. The Keowee Powerhouse, also known as the Keowee Hydro
Station, is located on the Keowee River approximately 12 mi downstream of the Jocassee
Powerhouse and 8 mi north of Seneca, South Carolina (Figure 2.1 -1).
The Keowee Development consists of Lake Keowee; the Keowee Dam; the Little River Dam;
four saddle dikes designated A, B, C, and D; the Oconee Nuclear Station (ONS) intake dike; a
gated concrete ogee spillway; a powerhouse with two generating units; and an intake structure
(Figure 2.1 -4).
Commercial operation of the Keowee Development began in 1971. Lake Keowee serves as the
lower reservoir for the Jocassee Pumped Storage Station. Water released from the Keowee
Hydro Station flows directly into Hartwell Lake, a USACE reservoir.
Duke Energy Carolinas, LLC 6 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

Figure 2.1-4. Lake Keowee Dam and Tailrace Area Facilities and Little River Dam Area
Facilities Map
p VHF. rN I-
-9
ti
6
5
IT,
A
It-324
Uzi]
Duke Energy Carolinas, LLC 7 401 WQC Application
Keowee-Toxaway Project (FERC no. 2503)
CN'J
E11-
n
Virginia
Legend
Keowee-Toxaway Relicensing
Tennessee
North
Carolina
Project Boundary
FERC Project No. 2503
Access Roads
Lake Keowee Dam and Tailrace
Area Facilities & Little River Dam Area
South
Caroiina
River Mile
Facilities Site Map
Georgia
D 0.6 1 1.5
INap Location
I
Miles
Dst S-..: FSRI Me,
RWb- NAD 1983 SlaWNn. Sudh Car Wine
Duke Energy Carolinas, LLC 7 401 WQC Application
Keowee-Toxaway Project (FERC no. 2503)

Table 2.1 -1. Physical Features of the Jocassee and Keowee Developments
Development Jocassee Keowee
River Keowee Keowee and Little
Drainage Area
Full Pond Elevation
Gross Storage Volume at
Full Pond
Usable Storage Volume
Surface Area at Full Pond
Shoreline including
Islands at Full Pond
Reservoirs
145 square miles
1,110.0 feet AMSL
1,206,798 ac -ft
225,387 ac -ft
(between 1110 feet AMSL
and 1080 feet AMSL)
7,980 acres
92.4 miles
435 square miles
800.0 feet AMSL
869,338 ac -ft
• 364,884 ac -ft (Existing License,
between 800 feet AMSL and 775
feet AMSL)
• 90,319 ac -ft (Existing
Operations, between 800 feet
AMSL and 794.6 feet AMSL)
• 161,727 ac -ft (Proposed
Operations, between 800 feet
AMSL and 790 feet AMSL)
17,660 acres
387.9 miles
Structure
Turbine Type
Number of Units
Authorized Installed
Capacity (per unit)
Total Authorized Installed
Capacity
Maximum Hydraulic
Capacity
Powerhouses
Semi - Outdoor
Reversible Pump
4
177.525 MW
710.10 MW
36,200 cfs
Concrete
Diagonal Flow
2
78.75 MW
157.5 MW
24,920 cfs
Notes: ac -ft — acre -feet; AMSL - above mean sea level; cfs - cubic feet per second; MW -
megawatt
Duke Energy Carolinas, LLC 8 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)
Dams
Jocassee Dam
Little River Dam
Type
Rock Fill with Earthen Core
Compact Earth Fill
Total Length
1,800 feet
1,800 feet
Height
385 feet
165 feet
Keowee Dam
Type
Compact Earth Fill
Total Length
3,500 feet
Height
165 feet
Structure
Turbine Type
Number of Units
Authorized Installed
Capacity (per unit)
Total Authorized Installed
Capacity
Maximum Hydraulic
Capacity
Powerhouses
Semi - Outdoor
Reversible Pump
4
177.525 MW
710.10 MW
36,200 cfs
Concrete
Diagonal Flow
2
78.75 MW
157.5 MW
24,920 cfs
Notes: ac -ft — acre -feet; AMSL - above mean sea level; cfs - cubic feet per second; MW -
megawatt
Duke Energy Carolinas, LLC 8 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

2.2 South Carolina Water Quality Criteria
The South Carolina Pollution Control Act (R. 61 -69, Classified Waters) provides a listing of all
named waterbodies, some specific unnamed waterbodies, their designated use classifications,
and locations.
Lake Jocassee is designated as trout -put, grow, and take (TPGT). TPGT are freshwaters suitable
for supporting growth of stocked trout populations and a balanced indigenous aquatic community
of fauna and flora. These waters are also suitable for contact recreation and as a drinking water
supply source after conventional treatment (SCDHEC 2012a).
Lake Keowee is designated as freshwaters (FW). Freshwaters are suitable for contact recreation
and as a source for drinking water supply after conventional treatment in accordance with the
requirements of the SCDHEC. Freshwaters are also suitable for fishing and the survival and
propagation of a balanced indigenous aquatic community of fauna and flora, as well as a water
supply for industrial and agricultural uses (SCDHEC 2012a).
A summary of the designated use classifications for Lake Jocassee and Lake Keowee watersheds
(located in South Carolina) is included in Table 2.2 -1. South Carolina has assigned state water
quality standards commensurate with the designated use classifications of a waterbody.
Duke Energy has compiled an extensive water quality database for the Project reservoirs based
on monitoring programs extending in time to immediately following original impoundment. The
FLA describes water quality indicators that have been characterized within the Project reservoirs
and tailwaters, in both historical and ongoing water quality monitoring assessments. Water
quality results for pH, turbidity, major nutrients (phosphorus and nitrogen), and chlorophyll a
were evaluated with respect to applicable water quality standards, and are summarized in FLA
Exhibit E, Section 3.4.1.2, which is included on the DVD supplied with this application.
Temperature and dissolved oxygen (DO) levels in Project flow releases are typically of primary
significance during hydroelectric project relicensing and DO is typically the only numeric standard
that becomes a compliance requirement for hydro project flow releases. A summary of South
Carolina water quality standards for these two water quality parameters is included in Table 2.2-
2.
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Table 2.2 -1. Designated Use Classifications of Waterbodies within the Jocassee and
Keowee Watersheds located in South Carolina
Watershed
Name
Description
Designated Use
Classification
Thompson River
From North Carolina -South Carolina
TN
state line to Lake Jocassee
Rock Creek
That portion within South Carolina
TN
(Toxaway River)
Whitewater River
From North Carolina -South Carolina
ORW, TPGT
state line to Lake Jocassee
Bear Creek
From North Carolina -South Carolina
TN
state line to Lake Jocassee
Bear Camp Creek
From North Carolina -South Carolina
TN
state line to Lake Jocassee
Corbin Creek
Entire tributary to Devils Fork Creek
ORW, TPGT
Limber Pole Creek
Entire tributary to Devils Fork Creek
TN
Lake
Jocassee
From headwaters to 0.3 mi below
Howard Creek
Highway 130 above flow
ORW, TPGT
augmentation system at the Bad Creek
Hydroelectric Project Dam
From just above the flow
Howard Creek
augmentation system at the Bad Creek
TN
Hydroelectric Project Dam to Devils
Fork Creek
Devils Fork Creek
From the confluence of Corbin Creek
TN
and Howard Creek to Lake Jocassee
Laurel Fork Creek
Entire tributary to Lake Jocassee
TN
Wright Creek
Entire tributary to Lake Jocassee
ORW, TPGT
Lake Jocassee
Entire lake
TPGT
Mill Creek
Entire tributary to Eastatoe Creek
TPGT
Eastatoe Creek
From its confluence with Laurel Creek
TPGT
Lake
to Lake Keowee
Keowee
Little River
Entire tributary to Hartwell Lake
FW
Martin Creek
Entire tributary to Hartwell Lake
FW
Lake Keowee
Entire lake
FW
Source: SCDHEC (2012a)
Notes: FW — Freshwaters; ORW — Outstanding Resource Waters; TN — Trout - Natural; TPGT — Trout -Put, Grow,
and Take
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Table 2.2 -2. South Carolina Numeric State Water Quality Standards Relevant to the
Project
Parameter
South Carolina Water Quality Standard
Temperature
Not to exceed 2.8 °C (5 °F) above natural temperatures up to 32.2 °C
(applies to heated
(90 °F)
effluents only)
Trout Waters: Not to vary from levels existing under natural
conditions, unless determined that some other temperature shall protect
the classified uses
Dissolved oxygen
Daily average not less than 5.0 mg/L
Low of 4.0 mg /L
Trout Waters: Not less than 6.0 mg /L
Source: SCDHEC (2012b)
Notes: mg /L — milligrams per liter
2.3 Existing Project Operation
Duke Energy operates the Project primarily for the purposes of hydroelectric generation and
supporting thermal electric generation and secondarily for water supply and recreation. The
Keowee Development is a conventional hydroelectric facility and the Jocassee Development is a
pumped- storage hydroelectric facility. Lake Keowee is the lower reservoir for the Jocassee
Pumped Storage Station. Duke Energy has historically operated the Jocassee Development to
meet its system's electrical demand. While the Keowee Development is also operated to meet
Duke Energy system electrical demand, it is also a designated source of standby emergency
power for ONS.
Typically, Lakes Jocassee and Keowee are at their highest levels during the late winter and early
spring months and then gradually decline to their lowest levels in the fall and early winter. The
Normal Maximum Elevations specified in the Existing License for both reservoirs are the same
elevation as the respective Full Pond Elevations (Table 2.1 -1), which are defined as the point at
which water would first spill from the dams if Duke Energy took no action (the lowest point
along the top of the floodgates).
2.3.1 Jocassee Development
Under the Existing License, Lake Jocassee is allowed to operate between 1,110 feet above mean
sea level (ft AMSL) and 1,080 ft AMSL. Historically, Duke Energy has operated Lake Jocassee
at or above 1,094 ft AMSL more than 80 percent of the time. Typical daily fluctuations of Lake
Jocassee elevations are less than approximately 1.5 ft; virtually all daily fluctuations are less than
2.9 ft.
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2.3.2 Keowee Development
Under the Existing License, Lake Keowee is allowed to operate between 800 ft AMSL and 775
ft AMSL. Based on Nuclear Regulatory Commission (NRC) requirements for ONS and other
operating considerations, Duke Energy generally maintains Lake Keowee at or above elevation
794.6 ft AMSL. Lake Keowee generally fluctuates less than 1.0 ft daily and almost all daily
fluctuations are less than 1.8 ft. A December 1995 agreement with the SCDHEC (Duke Power
Company et al. 1995) developed in accordance with Article 38 of the FERC license set the
minimum water release from Lake Keowee at a leakage flow, consistent with Duke Energy's
1968 agreement with the USACE and the Southeastern Power Administration (SEPA). Even
though the 1968 agreement with the USACE and was terminated and superseded by the
execution of the New Operating Agreement (NOA), discussed in Section 2.4.1 below, the
amount of leakage flow is unchanged, and neither the 1968 agreement nor the NOA stipulates a
specific leakage flow.
2.4 Existing Agreements that Influence Project Operations
2.4.1 New Operating Agreement
Duke Energy, the USACE, and the SEPA executed the NOA on October 17, 2014, which
terminated and replaced a 1968 agreement associated with the Existing License.
The NOA was developed to ensure the percent remaining usable water storage in the Duke
Energy and USACE systems will remain in balance when low inflow conditions develop and as
conditions become more severe. Under the NOA, declining remaining usable water storage in
the downstream USACE reservoir system triggers Duke Energy to release water from the
Keowee Development so both systems remain in balance until the Duke Energy system (i.e.,
Lakes Jocassee, Lake Keowee, and Bad Creek Reservoir) reaches 12 percent remaining usable
water storage. At that point, while downstream water flow releases from the Keowee
Development associated with hydroelectric generation would cease (excluding releases that may
be required by the FERC, for ONS operations or situations covered by the Maintenance and
Emergency Protocol (MEP)), approximately 650 ac -ft of water per week would continue flowing
downstream due to leakage and seepage, consistent with existing operations. Therefore, water
continues flowing into Hartwell Lake even during the most severe droughts. Further, at the point
of ceasing hydroelectric generation releases, without sufficient inflow, the remaining usable
water storage combined in the three Duke Energy reservoirs would continue to decline below 12
percent due to on- reservoir water withdrawals, surface evaporation, leakage, and seepage. Thus,
as the USACE system continues to decline below 12 percent remaining usable water storage, the
Duke Energy system remaining usable water storage would also continue to decline. The NOA
also includes operational effects of access to additional water storage in Lake Keowee currently
not available due to the operational limitations of ONS. The USACE completed an
Environmental Assessment of the potential effects of the NOA and issued a Finding of No
Significant Impact prior to executing the NOA (USACE 2014).
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2.4.2 Keowee - Toxaway Fishery Resources Memorandum of Understanding
As part of the licensing of the Bad Creek Hydroelectric Project, Duke Energy entered into a
Memorandum of Understanding (MOU) with the South Carolina Department of Natural
Resources (SCDNR) for the long -term management of the fishery resources in Lake Keowee,
Lake Jocassee, and their tributary streams. While not a party to the MOU, the US Fish and
Wildlife Service (USFWS) is also notified of certain activities associated with implementation of
the MOU. Through this MOU, SCDNR and Duke Energy personnel work cooperatively, and
include third parties as necessary, to design and implement data collection and other activities to
develop and enhance management strategies for fish in these areas. Activities and studies related
to the MOU were first implemented in 1996 and have continued through a series of work plans
that currently extend through 2015, when the next work plan will be developed.
2.4.3 Low Inflow Protocol
The Low Inflow Protocol (LIP), included as Appendix D of the RA, sets forth responses to
drought conditions in the Keowee - Toxaway Project river basin by RA signatories and others
withdrawing water from the Project. It includes defined drought stages, drought stage trigger
levels, drought stage recovery trigger levels, and water use reduction goals for each stage. The
LIP is closely linked to the USACE's Drought Plan for the downstream federal reservoirs and
the NOA. The LIP went into effect when the RA became effective on December 1, 2013.
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3.0 Overview of FERC Relicensing
Duke Energy began relicensing activities, including a substantial effort to foster collaboration
among regional stakeholders, five years prior to the submittal of the FLA to FERC. Relicensing
has followed FERC's Integrated Licensing Process (ILP) supplemented by a separate stakeholder
process aligned with the ILP, negotiation of the RA with stakeholders, and negotiation of the
NOA with the USACE and SEPA. All three processes were focused on producing a New
License reflecting comprehensive and coordinated development and management of the
waterway.
While the ILP includes opportunities for interested stakeholders to participate in the relicensing
process, Duke Energy devoted significant resources to enhancing stakeholder involvement in the
relicensing of the Project. These efforts have included public meetings, distribution of an
electronic newsletter, extensive use of the public relicensing website, and the formation of
relicensing teams. Since June 2009, the various relicensing teams including the Stakeholder
Team, study teams, Resource Committees, and Ad Hoc Committees met more than 175 times
combined to collaboratively identify interests, and key issues, define and implement studies,
analyze study results, and negotiate alternatives related to continued operation the Project.
3.1 Stakeholder Process
3.1.1 Stakeholder Team
The Stakeholder Team consists of representatives of local, state 2, and federal governmental
agencies, Native American tribes, non - governmental organizations, businesses, the public, and
Duke Energy. One of the primary responsibilities of the Stakeholder Team was the development
of the RA, which was signed in November 2013 after more than four years of collaboration and
negotiation. As stated earlier, the RA represents the collective vision of the 17 signatory parties
as to how the Project should be operated during the New License term.
3.1.2 Resource Committees
The Resource Committees (RCs) assisted in identifying studies related to their specific resource
areas, providing technical input, identifying participants for the Study Teams, and synthesizing
the findings of the Study Teams for review and consideration by the Stakeholder Team. The
seven RCs— Aquatics, Cultural Resources, Recreation, Shoreline Management, Water Quality,
Water Quantity and Operations, and Wildlife and Botanical —began meeting in October 2009.
The Water Quality RC focused on water quality issues associated with operation of the Project.
In addition to Duke Energy, the following organizations participated in the Water Quality RC:
Friends of Lake Keowee Society, Greenville Water, Lake Hartwell Association, NC Department
of Environment and Natural Resources, SCDHEC, SCDNR, and Upstate Forever. In addition to
scoping the water quality studies conducted as part of relicensing (see description below), the
2 SCDHEC was an Interested Party on the the Stakeholder Team and was represented at most Stakeholder Team
Meetings.
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Water Quality RC also advised the Stakeholder Team regarding appropriate water quality
protection and enhancement measures to incorporate into the RA.
3.1.3 Study Teams
Duke Energy's scientists, engineers, and consultants conducted 14 studies during the relicensing
of the Project. Each study was coordinated by its Study Team of technical experts who
participated in study plan development and implementation. The Study Teams began meeting
early in the process and concluded when the final study reports were issued. Those studies
critical to assessing water quantity, water quality, and aquatic resources are discussed in more
detail in Section 3.2 below. All 14 final study reports are included in Appendix E6 of the FLA,
which is provided on a DVD with this application.
3.1.4 Ad Hoc Committees
Ad Hoc Committees were formed as a means to address specific issues raised by the Stakeholder
Team that could not be resolved efficiently in the facilitated discussion of the larger team. These
five committees, made up of Stakeholder Team or RC members with particular resource
expertise and /or interest in the subject at hand, participated in detailed discussions and brought
recommendations back to the full Stakeholder Team.
3.2 Relicensing Studies
As required by 18 CFR §5.11, Duke Energy prepared and filed a Proposed Study Plan (PSP)
with the FERC on August 26, 2011. Duke Energy held the Initial PSP Meetings on September
13 and 14, 2011, in accordance with 18 CFR §5.11(e). Agency recommendations obtained
during these and other meetings and formal comments to the FERC were integrated into the
Revised Study Plan (RSP) filed with the FERC on December 22, 2011, and approved as
modified by the FERC per the Study Plan Determination Letter issued on January 27, 2012.
In 2012 and 2013, Duke Energy completed the 14 FERC- approved studies listed in Table 3.2 -1.
Of the 14 studies completed, two pertain directly to water quality: (1) Jocassee Forebay and
Tailwater Water Quality Study and (2) Keowee Reservoir Water Quality Model Study. Reports
for these studies are included in the FLA in Appendix E6 of Exhibit E. Summaries of the
objectives and results of these studies are provided in Section 4 of this application.
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Table 3.2 -1. Keowee - Toxaway Project Relicensing Studies
Fish Community Assessment & Entrainment Study
Hydro Structures National Register of Historic Places Eligibility Assessment Study
Recreation Use and Needs Study
Shoreline Erosion Study
Shoreline Classification Map Update Study
Jocassee Forebay and Tailwater Water Quality Study
Keowee Reservoir Water Quality Model Study
Reservoir Level and Project Flow Releases Study
Operations Model Study
Water Supply Study
Wetlands Study
Avian Study
Mammal Study
Botanical Study
3.3 Relicensing Agreement
Duke Energy and 16 other entities entered into the RA with an effective date of December 1,
2013.3 The RA represents the collective vision of the signatories for how the Project should be
operated during the term of the New License and addresses issues involving reservoir elevations,
water user needs, drought response, maintenance and emergency response, historic properties,
public recreation, species protection, shoreline management, water quality, and other resource
enhancement interests. Duke Energy's FLA, filed with the FERC on August 27, 2014, and this
401 WQC application incorporate measures consistent with the RA.
The Stakeholder Team described in Section 3.1.1 above developed the RA. In the course of
developing the RA, Stakeholder Team Members balanced competing resource and public
interests. This outcome was realized by identifying interests, developing objectives, and
collaborating to develop measures to protect, mitigate, and enhance resources, while providing
for other beneficial uses of the Project waters, including hydroelectric generation, consumptive
uses of Project water, and recreation. The RA includes measures associated with all aspects of
continued operation of the Project. The RA was filed with the FLA as Appendix E1 of Exhibit E
and is included on the DVD supplied with this application.
3.4 Proposed Project Operations & Water Quality Resource Measures
Proposed Project operations and proposed measures specific to water quality are described
below.
3 The 17 Parties to the Agreement are Duke Energy Carolinas, LLC; Advocates for Quality Development, Inc.; Anderson Area
Chamber of Commerce; City of Seneca; Commissioners of Public Works of the City of Greenville; Friends of Lake Keowee
Society, Inc.; Oconee County, South Carolina; Pickens County, South Carolina; Pickens County Water Authority; South Carolina
Department of Archives and History; South Carolina Department of Natural Resources; South Carolina Department of Parks,
Recreation and Tourism; South Carolina Wildlife Federation; The Cliffs at Keowee Vineyards Community Association, Inc.; The
Reserve at Lake Keowee; Upstate Forever; and Warpath Development, Inc.
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3.4.1 Proposed Project Operations
3.4.1.1 Reservoir Level Operating Ranges and Flow Releases under Normal Conditions
Except when operating in certain stages of the LIP (see Appendix D of the RA), the MEP (see
Appendix E of the RA), or other temporary conditions as may be approved by the FERC, the
Proposed Action is to operate the Project in accordance with the Normal Maximum Elevations
and Normal Minimum Elevations shown in Table 3.4 -1.
The Normal Minimum Elevation at Lake Jocassee would be increased from elevation 1,080 ft
AMSL to elevation 1,096 ft AMSL. The level of Lake Jocassee has historically been at or above
elevation 1,096 ft AMSL approximately 78 percent of the time (HDR Engineering 2012). Under
Duke Energy's proposed operations, the water level in Lake Jocassee would fall below elevation
1,096 ft AMSL only under low inflow, maintenance, or emergency conditions consistent with the
proposed LIP and MEP. Using the 73 -year historical unimpaired inflow to model proposed
operations, Lake Jocassee would fall below 1,096 ft AMSL approximately 3 percent of the time.
The Normal Minimum Elevation at Lake Keowee would be increased from elevation 775 ft
AMSL to 796 ft AMSL. Reservoir levels have historically been at or above elevation 796 ft
AMSL approximately 68 percent of the time (HDR Engineering 2012). Under proposed Project
operations, elevations would fall below 796 ft only under low inflow, maintenance, or
emergency conditions and only as allowed under the proposed LIP or MEP. Using the 73 -year
historical unimpaired inflow to model proposed operations, Lake Keowee would fall below 796
ft AMSL approximately 7 percent of the time.
Table 3.4 -1. Proposed Normal Maximum and Normal Minimum Elevations for Lake
Jocassee and Lake Keowee
Jocassee Pumped Storage Station and Keowee Hydro Station release water directly into Lake
Keowee and Hartwell Lake, respectively, so continuous minimum flows or minimum average
daily flow requirements from either hydroelectric facility are not proposed. Nonetheless, leakage
flows of approximately 650 acre -feet of water per week will continue to be released from Lake
Keowee into Hartwell Lake, consistent with agreements with SCDHEC (see Section 2.3.2
above), the LIP, and NOA.
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Normal Maximum Elevation
Normal Minimum Elevation
Reservoir
(ft AMSL)
(ft AMSL)
Lake Jocassee
1,110.0
1,096.0
Lake Keowee
800.0
796.0
Jocassee Pumped Storage Station and Keowee Hydro Station release water directly into Lake
Keowee and Hartwell Lake, respectively, so continuous minimum flows or minimum average
daily flow requirements from either hydroelectric facility are not proposed. Nonetheless, leakage
flows of approximately 650 acre -feet of water per week will continue to be released from Lake
Keowee into Hartwell Lake, consistent with agreements with SCDHEC (see Section 2.3.2
above), the LIP, and NOA.
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3.4.1.2 Project Operation under Drought Conditions
Project operations during periods of low inflow would be subject to the requirements of both the
LIP and the NOA. The LIP is described in detail below; the requirements of the NOA are
consistent with the LIP. Given both the NOA and LIP address downstream water flow releases
from Lake Keowee to support downstream water user needs during droughts, no continuous
minimum flows or minimum average daily flow requirements from either hydroelectric facility
are necessary or proposed.
The LIP allows reservoir elevations lower than the Normal Minimum Elevations specified in
Table 3.4 -1 when specific low inflow conditions exist, and includes provisions for limiting
downstream flow releases. The LIP defines triggers for implementing the protocol, and resultant
actions depend on the severity of the drought. There are five different drought stages in the LIP
(0 -4), and each is defined by remaining usable storage in the Duke Energy reservoirs or the
Drought Plan Level designated for the downstream USACE reservoirs, along with confirming
triggers of the US Drought Monitor designation and streamflows representative of the Upper
Savannah River Basin. Stage Minimum Elevations are defined for each drought stage. When a
subsequent stage of the LIP is reached, each Project reservoir must be within 0.25 ft of the Stage
Minimum Elevation of the previous stage of the LIP before each Project reservoir can be
lowered to the next Stage Minimum Elevation.
When operating in the LIP, Duke Energy will limit weekly flow releases from Keowee Dam to
no more than the maximum weekly flow release as stated for the applicable LIP stage, except for
flow releases that may be required for ONS operations, required by the FERC, or situations
covered in the MEP. The weekly flow release amount includes the sum of all water released
downstream from the Keowee Development (i.e., hydro unit generation plus hydro unit leakage,
dam seepage, and spillway gate releases).
When operating in the LIP near Stage Minimum Elevations, except for flow releases that may be
required for ONS operations, required by the FERC or situations covered by the MEP, Duke
Energy will not make an intentional flow release from Keowee Hydro Station if that flow release
would reduce the level of Lakes Jocassee or Keowee below its Stage Minimum Elevation as
specified for the applicable LIP stage. When operating in Stage 4, with remaining usable storage
below 25 percent but greater than 12 percent, Duke Energy will not release water flows from the
hydro units or flood gates of the Keowee Development if such flows would cause Lake Keowee
to fall below 791.5 ft AMSL. Further, in Stage 4 of the LIP when the remaining usable storage is
at or below 12 percent, Duke Energy will not make hydro unit or flood gate releases from
Keowee Dam (except releases required by FERC, for ONS operations, or in accordance with the
MEP). However, leakage flows of approximately 650 ac -ft per week will continue to be
provided from the Keowee Development during drought periods.
3.4.1.3 Project Operation during Maintenance and Emergency Conditions
Duke Energy proposes to implement the provisions of the MEP included as Appendix E of the
RA. The MEP specifies when Duke Energy will notify entities of conditions under which
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reservoir elevations or downstream flow releases will differ from what may be specified in a
New License (excluding operations under the LIP). The MEP lists the entities to be notified
and/or consulted, along with timeframes for doing so. Examples of situations when the MEP
might be used include hydro unit outages; dam safety emergencies; energy, voltage, or capacity
emergencies; lake drawdowns required for maintenance; flood events; and support for local or
regional emergencies.
3.4.2 Proposed Water Quality Resource Measures
Based on the findings of completed Project water quality monitoring and water quality modeling
studies, the Project water releases exhibit excellent water quality and will continue to do so under
proposed Project operation. As supported by the consensus of the Water Quality RC and the
signatories to the RA, Duke Energy proposes to continually monitor DO in the tailwaters of
Keowee Hydro Station and Jocassee Pumped Storage Station in August for the term of the New
License. Duke Energy proposes to submit the monitoring results to the SCDHEC annually by
November 30. The month of August was selected because historic water quality data indicate
DO levels are typically at their lowest during August.
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4.0 Assessment of Water Quality, Water Quantity, and Aquatic Resources
at the Project
The information presented below is a summary of historic water quality, water quantity, and
aquatic resource data and the results of relicensing studies related to compliance with South
Carolina water quality criteria (maintaining designated uses and associated water quality
standards) under the Proposed Action.
4.1 Water Quality
As described below, Lake Jocassee and Lake Keowee have historically met, currently meet, and
based on modeling study results, are expected to continue meeting the applicable South Carolina
designated uses and water quality standards (SCDHEC 2010)4. (See Exhibit E, Section E3.4.1.2
of the FLA for an extensive summary of historic water quality data collected at Lake Jocassee
and Lake Keowee.) Water quality studies indicate Duke Energy's proposed operation of the
Project is consistent with maintaining excellent water quality in support of South Carolina's
designated uses.
4.1.1 Dissolved Oxygen
The potential influence of hydroelectric operations on water quality is generally related to levels
of DO, and where applicable, total dissolved gases that occur in generation water releases as a
result of multiple, Project - specific factors. Due to the excellent reservoir water quality and the
design and elevation of the hydro station water intakes at the Project within the well- oxygenated
epilimnion of the two reservoirs, neither under - saturated nor supersaturated dissolved gas
conditions (including DO) have been known to occur in water releases from either development.
No violations of state DO water quality standards have been observed in the surface waters of
either impoundment, nor in the water released from Jocassee Pumped Storage Station or Keowee
Hydro Station.
Duke Energy performed two studies during relicensing that assessed water quality at the Project
based on existing and proposed operations: (1) Keowee Reservoir Water Quality Modeling
Study and (2) Lake Jocassee Forebay and Tailwater Water Quality Study. Additionally, Duke
Energy has collected water quality data in Lake Keowee since 1971 and Lake Jocassee since
1974. The sampling programs have consisted of different combinations of water quality
parameters, but typically include monitoring for water temperature, DO, conductivity, pH, and
nutrients. The information collected and analyzed during these studies was used to evaluate
water quality at the Project in comparison to the South Carolina water quality criteria (supporting
designated uses and complying with water quality standards). The relicensing studies and other
relevant data are described below.
4 As noted in Table E3.4 -10 in Exhibit E of the FLA, only state water quality standards for DO apply to Project
operations.
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4.1.1.1 Keowee Reservoir Water Quality Modeling Study
The goal of the Keowee Reservoir Water Quality Modeling Study (Sawyer et al. 2013)5 was to
evaluate the effects of the potential changes in Project operations on water quality in Lake
Keowee and the water releases from the Keowee Hydro Station. The study used the CE -QUAL-
W2 (W2) water quality model, a public domain model which has been employed extensively by
scientists and engineers internationally to model water quality in many types of aquatic
ecosystems, including large reservoirs like Lake Keowee. The W2 model was used to simulate
the effects of existing and proposed Project operations on the water quality in Lake Keowee and
the Keowee Hydro Station tailrace under varying meteorological conditions.
Data used to calibrate the W2 model were collected in 2011 in Lake Keowee, the Keowee and
Jocassee tailwaters, and tributary streams. Under the guidance of the Water Quality RC, the
model was used to evaluate an extreme low- inflow, low reservoir level year (2008) and high -
inflow year (1998), bracketing the range of water quality conditions likely to occur during future
Project operations. Flows for the W2 model were derived from the CHEOPSTM model which
was used by the Operations Scenario Ad Hoc Committee to assess various operational scenarios.
The scenario "September 2012 Trial Balloon" was modeled to evaluate potential changes in
water quality associated with changes in normal reservoir operating levels and implementation of
the LIP and MEP (Sawyer et al. 2013). Proposed Project operations are the same as those
modeled in the September 2012 Trial Balloon scenario, except the proposed LIP Stage 2 and 3
minimum elevations are 1 foot (ft) lower for Lake Jocassee than they were in the September
2012 Trial Balloon, and the proposed Normal Minimum, LIP Stage 0, and LIP Stage 1 Minimum
Elevations are 1 ft higher for Lake Keowee than they were in the September 2012 Trial Balloon.
The withdrawal zone for Keowee Hydro Station is influenced by an underwater weir, the top of
which is at approximately 765 ft AMSL. Consequently, Keowee Hydro Station pulls relatively
oxygen -rich water from nearer the reservoir surface instead of water with lower DO
concentrations from deeper in the lake. This important controlling structural feature will not
change with proposed Project operations.
W2 modeling results indicate DO levels in Keowee Hydro Station water releases will meet or
exceed state water quality standards under proposed Project operations. The excellent water
quality in the reservoir and the upper level withdrawal from the lake are the primary reasons flow
releases have consistently met and are predicted to continue to meet state water quality standards
for DO. A summary of key study findings include the following.
• Keowee Hydro Station Tailrace DO: All modeled DO results in the Keowee Hydro
Station tailrace were well above the South Carolina Water Quality Standards of 5.0 mg /L
daily average and 4.0 mg /L instantaneous. Modeled DO concentrations in Keowee
5 See FLA Exhibit E, Appendix E6 for a complete copy of the final study report.
6 CHEOPSTM is a computer -based hydroelectric operations model that assesses the impacts of simulated
hydroelectric project operating conditions on flows and reservoir levels. See HDR Engineering 2014a (included in
Exhibit E Appendix E6 of the FLA) for additional information about operations modeling.
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Hydro Station water releases were slightly reduced under historic low inflow scenarios,
yet remained consistently compliant with applicable water quality standards. Modeled
scenarios with similar hydrology indicated that DO concentrations in tailwaters
associated with hydro generation were relatively insensitive to changes from existing to
proposed operations.
• Keowee Hydro Station Tailrace Temperature: Water temperature in the Keowee Hydro
Station tailrace is influenced by reservoir levels in both Lake Jocassee and Lake Keowee,
operations of both Jocassee Pumped Storage Station and Keowee Hydro Station, and the
temperature of the Jocassee Pumped Storage Station water releases into Lake Keowee.
Modeling of various inflow and operational scenarios illustrated that the high -inflow
(1998) scenario consistently exhibited summertime water release temperatures lower than
release temperatures under the low -inflow (2008) scenarios.
4.1.1.2 Jocassee Forebay and Tailwater Water Quality Study
The goal of the Lake Jocassee Forebay and Tailwater Water Quality Study (Reservoir
Environmental Management, Inc. 2013) was to provide the information necessary to determine
the effects of recent Project modifications (i.e., the installation of new hydro unit runners in
2010 -2011) on water quality in the forebay and tailwater of Jocassee Pumped Storage Station.
Water temperature and DO data were collected in the Jocassee Pumped Storage Station forebay
and tailwaters (Lake Keowee) from April through October 2012. Data were compared to the
applicable water quality standards and historical water quality data collected at the sites.
The data collected during the study were consistent with conditions observed between 2008 and
2011. During the period monitored, DO concentrations in the Jocassee Pumped Storage Station
forebay or tailwater met South Carolina water quality standards at all times. Four years of
Jocassee Pumped Storage Station tailwater (Lake Keowee) monitoring have demonstrated the
water released from Lake Jocassee has DO concentrations well above (i.e., in compliance with)
the applicable South Carolina Water Quality Standards (SCDHEC 2012b).
The near - saturation levels of DO in the tailwater can be attributed primarily to generation flow
withdrawals from the Jocassee Pumped Storage Station forebay that originate from the Lake
Jocassee epilimnion, or the upper -most, well- oxygenated portion of the water column. This
selective epilimnetic withdrawal corresponds to the Jocassee Pumped Storage Station intakes,
which are between 1043 and 1067 ft AMSL. Similarly, during pumping operations, water
pumped back to the forebay originates from the well- oxygenated Lake Keowee epilimnion.
Pumping generally results in forebay DO concentrations very similar to the hydroelectric flow
releases which had occurred within a similar timeframe. These important controlling structural
features will not change with proposed Project operations.
7 See FLA Exhibit E, Appendix E6 for a complete copy of the final study report.
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4.1.2 Modeled Cumulative Effects
4.1.2.1 Modeled Effects of Hypothetical Nutrient Loading Increases
The potential impacts attributable to hypothetical future increases in nutrient loading to Lake
Keowee, although recognized by the Water Quality RC as watershed - derived and not directly
related to Project operations, were nonetheless modeled by the Study Team at the request of the
RC in order to examine the potential effects of anticipated regional population increase. A series
of ten modeled scenarios were developed to analyze predicted water quality impacts resulting
from hypothetical increased point and non -point source nutrient loading. Increasing modeled
nutrient loading by as much as ten -fold did not result in any water quality standard violations. A
modeled combination of doubled non -point nutritive inputs (mimicking hypothetical watershed
disturbances or land use changes), coupled with the addition of a hypothetical 8- million gallon
per day (MGD) wastewater treatment plant, produced localized increases of total phosphorus and
chlorophyll a in the reservoir, yet predicted concentrations of both constituents were below
applicable SCDHEC water quality standards, and the DO in Project tailwaters consistently
remained well above water quality standards (Sawyer et al. 2013).
4.1.2.2 Modeled Effects of Climate Change Scenarios
Following the completion of W2 model runs conducted for the Keowee Reservoir Water Quality
Modeling Study (Sawyer et al. 2013), additional scenarios were analyzed at the request of the
Water Quality RC to examine the potential water quality effects of a set of low- and high- impact
climate change assumptions (Sawyer et al. 2014)8. The scenarios were modeled using updated
CHEOPSTM- derived flows from the final proposed (WQ4) operational scenario for years 2008
(low- inflow) and 1998 (higher inflow). Potential climate change effects were evaluated
separately by adding 3 °F (low- impact scenario) and 6 °F (high- impact scenario) to the air
temperatures in the meteorological input data file, consistent with the operational modeling
approach.
Modeled water quality results from climate change scenarios showed minor water temperature
increases and minimal corresponding reductions in DO concentration as compared to the
modeled scenarios without air temperature adjustments. Modeled Lake Keowee tailrace
temperatures were typically 1 to 2 °F warmer for the low- impact scenario and 2 to 3 °F warmer
for the high- impact scenario. Modeled Lake Keowee forebay and tailwater DO concentrations
corresponding to the low- and high - climate change scenarios were reduced by only 0.1 to 0.2
mg/L, or 0.2 to 0.3 mg /L, respectively, compared to the baseline scenario with unadjusted air
temperatures. Scenarios modeled with actual 2011 air temperatures resulted in water
temperatures and DO concentrations that were intermediate between those for the low- and high -
impact climate change scenarios.
Consistent with previous W2 modeling, the low inflow (2008- based) hydrology resulted in
greater relative water quality impacts, although very minor in magnitude insofar as a reduction in
DO concentration, compared to climate change scenarios run with 1998 hydrology. Modeled
8 See FLA Exhibit E, Appendix E6 for a complete copy of the final study report.
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DO concentrations in the Keowee Hydro Station tailrace, under even the most extreme modeled
hydrology and climate change scenario, remained above 6.0 mg/L, and substantially above the
5.0 mg/L daily average water quality standard.
4.1.3 Other Water Quality Parameters
A variety of water quality indicators, including turbidity, pH, concentrations of major nutrients
(nitrogen and phosphorus) and chlorophyll a have been evaluated and are summarized in the
FLA for the Project reservoirs (see FLA Exhibit E, Section 3.4.1.2, included on the DVD
supplied with this application). These and other commonly measured water quality indicators
are useful in characterizing the Project reservoirs' water quality as excellent from the standpoint
of demonstrated consistent compliance with applicable numeric SCDHEC water quality
standards. Patterns of nutrient and chlorophyll concentrations have established the reservoirs as
having an oligotrophic (nutrient -poor) status. As a direct result, the Project reservoirs remain
unimpaired by oxygen- demanding conditions that can result from nutritive inputs coupled with
microbiological processes, and therefore, seasonal, near - saturation concentrations of DO in the
reservoir epilimnion strata are the norm. However, because these additional water quality
indicators are responsive to watershed influences and are generally un- responsive and un- linked
to Project operations, no further discussion of these parameters has been included in this
application.
4.2 Water Quantity
As discussed in Section 3.2 above, Duke Energy performed three studies associated with water
quantity during relicensing9: (1) Reservoir Level and Project Flow Releases Study; (2)
Operations Model Study; and (3) Water Supply Study. The information collected and analyzed
during these studies was used to evaluate water availability as a result of proposed Project
operations, including meeting the existing and future competing demands and uses including
hydropower generation, water supply, aquatic habitat, and recreation.
The CHEOPSTM water quantity model10 was used to evaluate the effects of various operational
scenarios on the downstream USACE reservoirs including water flow releases from the J. Strom
Thurmond Dam using the 73 years of historic inflow data. During periods of normal inflow,
simulated flow releases from the Keowee Development were associated with hydroelectric
generation to meet system electrical demand. During periods of low inflow, the models
simulated Project and downstream reservoir levels and flow releases consistent with the LIP and
NOA.
As described below, Duke Energy's proposed operation of the Project will ensure water
availability to support South Carolina's designated uses.
9 All study reports are included in the Project FLA, Exhibit E, Appendix E6.
io Duke Energy and the USACE used USACE's Hydrologic Engineering Center Reservoir System Simulation
(HEC- ResSim) model to evaluate various operational alternatives when developing the NOA.
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4.2.1 Operations Modeling
Duke Energy used a computer -based hydrologic /hydraulic water quantity simulation model
(CHEOPSTM) of the two Project reservoirs, the upstream Bad Creek Reservoir, and the three
large downstream USACE reservoirs to evaluate the potential effects of Project operations. The
CHEOPSTM model was used to evaluate the capability of the system to operate under various
scenarios and, therefore, provide stakeholders with information on how well or poorly particular
scenarios met their individual and collective interests related to water quantity. The model has
six nodes that correspond to the major hydraulic junctures in the modeled river system. The
model accounts for inflows, discharges, changes in reservoir storage, water withdrawals, and
surface evaporation, and power generation at the various nodes. Modeled scenarios described
how each node in the model would respond to user - defined specific operating rules or
conditions.
As part of the Operations Model study, three scenarios were developed: Existing License,
Baseline (Existing Operations), and Proposed Operations (Blend 2Db v2). These scenarios were
run using the CHEOPSTM model with water use projections from the Water Supply Study; the
HEC- ResSim model was used for the evaluation of the NOA with similar results ( USACE 2012).
4.2.2 Project Reservoir Elevations
Duke Energy does not propose to change the Normal Maximum Elevations for either reservoir,
but does propose changes to the Normal Minimum Elevations. The proposed Normal Minimum
Elevations are low enough to allow for drawing down the reservoirs when substantial inflows are
forecast and during dry periods without triggering the LIP, but are high enough to ensure public
water supply intakes and Project Access Area boat ramps remain operational. The current and
proposed Normal Maximum Elevations and Normal Minimum Elevations are summarized in
Table 4.2 -1. Table 4.2 -2 provides a summary of surface elevations required to support various
water uses at Lake Jocassee and Lake Keowee.
Table 4.2 -1. Current and Proposed Normal Maximum and Normal Minimum
Elevations for Lakes Jocassee and Keowee
Note: The current minimum operating level for Lake Keowee is 794.6 ft AMSL to accommodate
normal operations at ONS.
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Current and Proposed
Current Normal
Proposed Normal
Reservoir
Normal Maximum
Minimum Elevation
Minimum Elevation
Elevation
(ft AMSL)
(ft AMSL)
(ft AMSL)
Lake Jocassee
1,110.0
1,080.0
1,096.0
Lake Keowee
800.0
775.0
796.0
Note: The current minimum operating level for Lake Keowee is 794.6 ft AMSL to accommodate
normal operations at ONS.
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Table 4.2 -2. Critical Elevations for Lake Jocassee and Lake Keowee
Notes: ac -ft — acre -feet, ft AMSL — feet above mean sea level; N/A — not applicable
The proposed Normal Minimum Elevation for Lake Jocassee provides operating flexibility at
Jocassee Pumped Storage Station while minimizing increases in fish entrainment associated with
Bad Creek Hydroelectric Project pump -back operations when the reservoir elevation is below
1,096 ft AMSL. All existing Project Access Area boat ramps are usable at this elevation as well.
Historically (including drought periods), Lake Jocassee has remained at or above elevation 1,096
ft AMSL about 78 percent of the time.
The proposed Lake Keowee Normal Minimum Elevation of 796 ft AMSL will add a 1.4 -ft buffer
to the current minimum reservoir elevation needed for normal ONS operation. The proposed
Lake Keowee Normal Minimum Elevation will also ensure access to the Project Access Area
boat ramps. Historically (including drought periods), Lake Keowee has remained at or above
elevation 796 ft AMSL about 68 percent of the time.
The higher Normal Minimum Elevations will reserve 116,650 ac -ft of storage in Lake Jocassee
and 22,683 ac -ft of storage in Lake Keowee to be used only when operating under the LIP. After
the planned ONS modification completion date of December 1, 2019, 94,091 ac -ft of additional
storage (the volume in Lake Keowee between elevation 796 and 790 ft AMSL) will be reserved
for use when operating under the LIP.
4.2.3 Water Supply
The Water Supply Study (HDR Engineering 2014b; see FLA Exhibit E, Appendix E6)
documented current water withdrawals, water returns, and overall water use for more than 60
public water and wastewater utilities throughout the Savannah River Basin, including the
Keowee - Toxaway River Basin. The study further estimated future water withdrawals and
returns for the next 50 years based on reasonable growth projections and assumptions. Those 50-
year projections were in turn a key input to the operations model for that model's projections
related to future operating scenarios.
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Lake Jocassee
Elevation
(ft AMSL )
Lake Keowee
Elevation
(ft AMSL)
Normal Full Pond Elevation
1,110.0
800.0
Level at Lake Jocassee below which fish entrainment becomes
elevated during pump back at the Bad Creek Project
1,096.0
N/A
Existing ONS lowest level operating restriction on Lake
Keowee
N/A
794.6
Lowest public boat ramp becomes unusable
1,080.0
786.7
City of Seneca water intake structure operational limit
N/A
775.0
Lowest level for hydropower operations
1,080.0
775.0
Greenville Water intake structure operational limit
N/A
770.0
Notes: ac -ft — acre -feet, ft AMSL — feet above mean sea level; N/A — not applicable
The proposed Normal Minimum Elevation for Lake Jocassee provides operating flexibility at
Jocassee Pumped Storage Station while minimizing increases in fish entrainment associated with
Bad Creek Hydroelectric Project pump -back operations when the reservoir elevation is below
1,096 ft AMSL. All existing Project Access Area boat ramps are usable at this elevation as well.
Historically (including drought periods), Lake Jocassee has remained at or above elevation 1,096
ft AMSL about 78 percent of the time.
The proposed Lake Keowee Normal Minimum Elevation of 796 ft AMSL will add a 1.4 -ft buffer
to the current minimum reservoir elevation needed for normal ONS operation. The proposed
Lake Keowee Normal Minimum Elevation will also ensure access to the Project Access Area
boat ramps. Historically (including drought periods), Lake Keowee has remained at or above
elevation 796 ft AMSL about 68 percent of the time.
The higher Normal Minimum Elevations will reserve 116,650 ac -ft of storage in Lake Jocassee
and 22,683 ac -ft of storage in Lake Keowee to be used only when operating under the LIP. After
the planned ONS modification completion date of December 1, 2019, 94,091 ac -ft of additional
storage (the volume in Lake Keowee between elevation 796 and 790 ft AMSL) will be reserved
for use when operating under the LIP.
4.2.3 Water Supply
The Water Supply Study (HDR Engineering 2014b; see FLA Exhibit E, Appendix E6)
documented current water withdrawals, water returns, and overall water use for more than 60
public water and wastewater utilities throughout the Savannah River Basin, including the
Keowee - Toxaway River Basin. The study further estimated future water withdrawals and
returns for the next 50 years based on reasonable growth projections and assumptions. Those 50-
year projections were in turn a key input to the operations model for that model's projections
related to future operating scenarios.
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Water yield analyses were completed for the Existing Operations (Baseline) scenario and the RA
(Blend 2Db v2) scenario which is consistent with proposed Project operations. The two water
yield evaluations conducted for the RA (Blend 2Db v2) scenario include an analysis using the
critical intake elevation constraint and an analysis using the full usable reservoir storage
constraint. The RA (Blend 213b v2) scenario water yield analysis is intended to assess the
Project's future ability to support regional water supply needs over the next 50 years, including
during extended drought periods. Two public water suppliers (City of Seneca and Greenville
Water) own and operate water intakes on Lake Keowee. These intakes are operational at
reservoir elevations as low as 775 and 770 ft AMSL, respectively. The minimum reservoir
elevation modeled at Lake Keowee using the CHEOPSTm model remained above 790.0 ft
AMSL. Therefore, both intakes will continue to be operational under the proposed Normal
Minimum Elevation at Lake Keowee as well as the reduced reservoir elevation allowed under the
LIP.
The LIP includes provisions for Duke Energy, Greenville Water, and City of Seneca to
implement water conservation measures during certain LIP Stages. Further, the LIP stipulates
that Duke Energy require, to the maximum feasible extent, new, expanded, and modified large
water intakes constructed at the Project to be operable with Lake Keowee at its hydro operational
limit of 775 ft AMSL. These measures plus the regional cooperative efforts required by the LIP
will enhance protection of the water supply in the Upper Savannah River Basin.
4.2.4 Downstream Effects
Water releases from Keowee Hydro Station flow directly into Hartwell Lake, a hydroelectric
reservoir operated by the USACE. The USACE operates Hartwell Lake, as well as the Richard
B. Russell and J. Strom Thurmond hydroelectric developments immediately downstream of
Hartwell Lake, in accordance with its operational plans, the USACE Savannah River Drought
Plan, and electric generation needs for use by SEPA. The USACE's operation of the J. Strom
Thurmond Project directly affects flow releases into the Savannah River.
Historically, flow releases from Lake Keowee are characterized by well- documented, excellent
water quality (see Section 4.1) that consistently exceeds all applicable state water quality
standards for DO. Keowee Hydro Station operations are projected to continue assuring excellent
water quality characteristics in released water, thereby helping to assure designated uses of the
downstream Savannah River are met. Furthermore, extensive water quality modeling studies
indicate this ongoing trend will prevail in the future. This is attributable to water released from
Keowee Hydro Station coming from oxygen- saturated water from near the top to the reservoir
water column, as well as the very low nutrient status of the reservoir.
Due to the relative smaller combined size of the Duke Energy reservoirs (Bad Creek and
Keowee - Toxaway Projects) and their contributing drainage areas compared to the USACE
reservoirs (Harwell, Richard B. Russell, and J. Strom Thurmond) and their drainage areas, water
quantity modeling has indicated the Proposed Action (Blend 2Db v2) scenario will not
significantly affect long -term USACE reservoir elevations or energy production at the USACE's
developments. Relative differences in downstream Savannah River flow regimens potentially
attributable to Proposed Operations, compared to Existing Operations, are minor and would
occur infrequently (HDR 2014a).
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As discussed in Section 2.4.1, the NOA executed in October 2014 by Duke Energy, SEPA, and
the USACE ensures that when sustained low inflow conditions develop in the Savannah River
Basin, remaining usable water storage in the Duke Energy and USACE systems remains in
balance as the USACE releases water from J. Strom Thurmond Dam. During development of
the NOA, the USACE completed a thorough Environmental Assessment of the potential effects
of the NOA and issued a Finding of No Significant Impact prior to executing the NOA (USACE
2014). The USACE Environmental Assessment summarized results from predictive water
quality models applied by the Georgia Department of Natural Resources — Environmental
Protection Division (DNR -EPD) to the Savannah River downstream of J. Strom Thurmond Dam,
and also to the lower, estuarine section of the Savannah River, including Savannah Harbor
(USACE 2012).11
The 2012 USACE's Savannah River Drought Plan (Drought Plan) stipulates an adaptive
management approach when flow releases from J. Strom Thurmond are below 3,800 cfs during
the months of November, December, and January. During such periods, state and/or federal
regulatory agencies in Georgia and /or South Carolina can request the USACE increase flow
releases from the J. Strom Thurmond Dam for the purpose of supporting downstream Savannah
River water quality, including in the Savannah Harbor. As a result, adaptive management flow
releases could be implemented during Drought Plan Levels 2, 3, and/or 4. If the USACE
implements such flow releases, the USACE would increase the flow release from J. Strom
Thurmond Dam above the minimum allowed during those months (for a given drought level) up
to as much as 3,800 cfs to support downstream water quality needs. This potential increase in
flow rate in such circumstances was noted by the USACE in its Environmental Assessment of
the NOA. Because such adaptive management flow releases would likely reduce the remaining
usable water storage in the USACE's three reservoirs as compared to what would have been
released without the increased adaptive management flows, Duke Energy would then be
contractually obligated under the NOA to release additional flow from Keowee Hydro Station in
order to balance the remaining usable water storage in the Duke Energy reservoirs.
Water quality in the Savannah River downstream of J. Strom Thurmond Reservoir can be linked
in part to the magnitude and frequency of releases from J. Strom Thurmond Dam. The summer
and early fall seasons typically present the most challenging circumstances for attainment of DO
water quality standards in the Savannah River downstream of J. Strom Thurmond Dam, due to
both the lower oxygen solubility at seasonally increased water temperatures and increased rates
of microbial metabolism in the Savannah River, potentially increasing oxygen demand.
Significantly, the Savannah River below J. Strom Thurmond Dam assimilates both non -point
nutritive inputs as well as treated wastewater inputs from several National Pollution Discharge
Elimination System (NPDES)- permitted outfalls. These inputs, as well as other factors such as
" The DNR -EPD used the RIV1 (One - dimensional Dynamic Hydraulic and Water Quality) Model to investigate
potential DO sags in the Savannah River mainstem downstream of the J. Strom Thurmond Dam to the US
Geological Survey (USGS) Gage at Clyo, Georgia, under selected flow release assumptions from the J. Strom
Thurmond Dam. For the further downstream estuarine portion of the river basin, including Savannah Harbor, the
US Environmental Protection Agency (USEPA)- developed EFDC (Environmental Fluid Dynamics Code) and
WASP (Water Quality Analysis Simulation Program) models were used in a separate effort related to the
development of a Total Maximum Daily Load (TMDL) analysis.
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sediment oxygen demand, will typically have the most significant influence on water quality
downstream of J. Strom Thurmond Dam.
In conjunction with Project relicensing, Duke Energy used the CHEOPSTM model to investigate
the potential effects of various operational scenarios on reservoir elevations and downstream
flow releases. Model scenarios developed for current Project operations and the Proposed
Action (Blend 213b v2) were run with period -of- record flows for the system, and separately, for
drought years 12. For purposes of this analysis, it was assumed the USACE would continue to
operate its three reservoirs consistent with the Drought Plan and the NOA.
CHEOPSTM model results reveal that for drought years, J. Strom Thurmond Hydro Station would
release on average about 0.6 percent less water under Proposed Operations (Blend2Db_v2_73yr)
compared to Existing Operations during the time period April- December (the period identified as
most likely to experience DO concerns). Year -by -year results within the modeled output,
however, range from a 13.2 percent reduction to a 2.6 percent increase in water being released
under Proposed Operations (Appendix A, Table A -1).
The range of differences and average difference in flow releases were smaller for J. Strom
Thurmond Hydro Station as compared to differences for Keowee Hydro Station (Appendix A,
Table A -2). This is consistent with the relatively small drainage area contribution, and therefore
effect, of flows released from Keowee Hydro Station when compared to the much larger inflows
from the remainder of the J. Strom Thurmond watershed.
Differences in Keowee Hydro Station flow releases between the Existing Operation scenario and
Proposed Operation scenario are significantly attenuated in time and space as the flow difference
travels downstream through the USACE's reservoirs as demonstrated by the timing of the largest
differences in flows, both increases and decreases, under each scenario. For example, the largest
negative percent difference (i.e., decrease) in flows at J. Strom Thurmond for the Proposed
Operations scenario was 13.2 percent in 1941, but flow releases from Keowee Hydro Station for
this same year increased by 3.3 percent. In some years, including notably the severe drought
years 2007 and 2008, the Proposed Operations scenario resulted in either no change or an
increase in flow releases from J. Strom Thurmond. Further, of the 50 drought years, 26 percent
modeled an increase in flow releases from J. Strom Thurmond Hydro Station coinciding with a
decrease in flow releases at Keowee Hydro Station or vice versa. Clearly, the magnitude and
timing of flow releases from the J. Strom Thurmond Project into the downstream Savannah
River are affected by more factors than simply releases from Keowee Hydro Station. Such
differences in J. Strom Thurmond flow releases between Existing Operations and Proposed
Operations would also be subject to significant channel routing attenuation downstream of the J.
Strom Thurmond Dam. Regardless, flow releases from J. Strom Thurmond Dam are projected to
be in compliance with the USACE's Drought Plan minimum flows.
12 Drought years were identified as a year in which the USACE's 2012 Savannah River Drought Plan was triggered.
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4.3 Aquatic Resources
As described below, the aquatic resource studies indicated the Proposed Action will not
adversely affect the aquatic ecosystem in the vicinity of the Project.
4.3.1 Rare, Threatened, and Endangered Species
There are no federally listed Rare, Threatened, or Endangered species within the Project
reservoirs or affected by operation of the Project.
4.3.2 Special and Unique Habitats
4.3.2.1 National Wild and Scenic Rivers
A portion of the Horsepasture River which flows into Lake Jocassee is the only federally
designated Wild and Scenic River in the vicinity of the Project. The downstream extent of the
Wild and Scenic River corridor is located adjacent to, but not within, the Project Boundary. The
portion of the Horsepasture River designated as a Wild and Scenic River is managed by the US
Forest Service to maintain and enhance the scenic and riparian features of the river and to
provide water - oriented recreation in a natural setting. Proposed Project operation will not
adversely affect this resource.
4.3.2.2 National Estuarine Research Reserves
There are no National Estuarine Reserves within the Project or affected by the Project.
4.3.2.3 National Ecological Reserves
There are no National Ecological Reserves within the Project or affected by the Project.
4.3.2.4 State Scenic Rivers
There are no SCDNR - listed State Scenic Rivers within the Project or affected by the Project.
4.3.3 Fisheries
In conjunction with relicensing, Duke Energy summarized available data regarding the health of
fish populations at the Project (Duke Energy Carolinas 2013; see FLA Exhibit E, Appendix E6).
Proposed Project operations will not adversely affect these populations or the habitats on which
they depend.
4.3.3.1 Littoral Fish Spawning and Reproduction
Littoral fish populations at Project reservoirs are healthy and consistent with population levels
that would be expected given the relatively low productivity of the Project reservoirs. Project
operations under the Proposed Action would be consistent with existing and historic operations
except the Proposed Action operations will reduce the extent of reservoir drawdowns in Lake
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Jocassee and Lake Keowee as compared to existing Project operations, potentially providing
more stability to littoral fish habitat.
4.3.3.2 Lake Jocassee Pelagic Trout Fishery
Lake Jocassee is one of only a few reservoirs in South Carolina possessing the necessary
combination of water temperatures and DO to allow the persistence and coexistence of both a
warmwater and a coldwater (trout) fishery year- round. The sustainability of this fishery is
partially dependent on the availability of suitable pelagic habitat, specifically, a hypolimnion that
possesses water temperatures <20 °C and DO >5 mg /L during the critical summer and fall
months. During extreme drought years, Lake Jocassee can experience periods of relatively low
reservoir elevations. However, habitat monitoring since reservoir impoundment indicates year -
to -year fluctuations in reservoir elevations alone have not influenced the amount of pelagic trout
habitat; therefore, it is not expected for the Lake Jocassee trout fishery to be adversely affected
by the Proposed Action (William Foris, Duke Energy, Personal Communication, October 15,
2013).
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5.0 Conclusion
Duke Energy has allocated a substantial amount of effort and resources throughout and prior to
the relicensing process to ensure the data needs of stakeholders were met, including that of the
SCDHEC for 401 WQC. Collectively, the water quality data collected by Duke Energy to
support certification and the assessments included in this application indicate the Proposed
Action will meet applicable South Carolina designated uses and associated water quality
standards.
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6.0 Literature Cited
Duke Energy Carolinas, LLC. (Duke Energy) 2013. Fish Community Assessment Study Plan
Final Report. Duke Energy Carolinas, LLC, Charlotte, NC. January 2013.
2014. Comprehensive Environmental, Engineering, and Economic Impact Analysis Report
for Revising the 1968 Operating Agreement for the Keowee - Toxaway Project. April 4, 2014.
Duke Power Company and South Carolina Department of Health and Environmental Control.
1995. Federal Energy Regulatory Commission Minimum Streamflow Compliance
Agreement Project No. 2503 (Keowee - Toxaway). December 1995.
HDR Engineering. 2012. Reservoir Level and Project Flow Releases Study for the Keowee -
Toxaway Relicensing Project (FERC No. 2503). Charlotte, NC. November 2012.
2014a. Operations Model Scenario Documentation Report. Prepared by HDR
Engineering Inc. for Duke Energy Carolinas, Inc. May 2014.
2014b. Water Supply Study Report, Keowee - Toxaway Relicensing Project. Charlotte,
NC. June 2014.
Reservoir Environmental Management, Inc. 2013. Jocassee Forebay and Tailwater Water
Quality Report. Prepared for Duke Energy Carolinas, LLC. February 2013.
Sawyer, A. F., R. J. Ruane, and J. C. Knight. 2013. Keowee Reservoir Water Quality Modeling
Study Report. Includes Appendices A -E. Prepared for Duke Energy Carolinas, LLC.
March 2013.
2014. Keowee Reservoir Water Quality Modeling Study Addendum. CE- QUAL -W2
Model Results from WQ4 Operations Under Climate Change Scenarios. Prepared for
Duke Energy Carolinas, LLC. May 2014.
South Carolina Department of Health and Environmental Control (SCDHEC). 2010. Watershed
Water Quality Assessment: Savannah River Basin. Technical Report No. 0217-10. Bureau
of Water. Columbia, South Carolina.
2012a. R.61 -69 Classified Waters. Columbia, SC. June 22. 2012. [Online] URL:
http: / /www.scdhec.gov/ environment /water /regs/R.61- 69.pdf. (Accessed September 12
2014.)
2012b. R.61 -68 Water Classifications and Standards. Columbia, SC. June 22. 2012.
[Online] URL: https: / /www.scdhec.gov/ environment /water /regs /R.61- 68.pdf. (Accessed
September 12, 2014.)
US Army Corps of Engineers (USACE). 2012. Final Environmental Assessment and Finding of
No Significant Impact - Drought Plan Revision, Savannah River Basin. July 2012.
2014. Final Environmental Assessment: New Operating Agreement Between U.S. Army
Corps of Engineers, Southeastern Power Administration, and Duke Energy Carolinas,
LLC. Savannah District USACE, October 2014.
Duke Energy Carolinas, LLC 33 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

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Appendix A
Keowee Hydro Station and J. Strom Thurmond Hydro Station Flow Releases during
Drought Years
Duke Energy Carolinas, LLC 35 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

(This page intentionally blank)

Table A -1. April - December Average J. Strom Thurmond Hydro Station Flow Releases
for Drought Years (Projected Withdrawals with Historical Hydrology)
Year
April - December Average Flow Releases (cfs)
percent Difference
Compared to
Existing Operations
Existing Operations
(BaseProjected_2012 -08-
23 73 r
Proposed Operations
(Blend2Db v2_73yr)
1940
7,435
7,405
-0.4
1941
5,749
4,988
-13.2
1942
6,413
6,399
-0.2
1944
7,336
7,331
-0.1
1945
6,967
6,960
-0.1
1946
7,522
7,523
0.0
1947
7,727
7,684
-0.6
1951
6,011
6,007
-0.1
1952
6,139
6,120
-0.3
1953
6,617
6,619
0.0
1954
4,986
4,855
-2.6
1955
4,285
4,333
1.1
1956
4,997
5,105
2.2
1957
7,223
7,235
0.2
1958
6,309
6,308
-0.0
1959
7,501
7,478
-0.3
1962
6,442
6,417
-0.4
1963
7,774
7,784
0.1
1966
6,327
6,335
0.1
1968
6,639
6,630
-0.1
1970
4,826
4,811
-0.3
1971
7,465
7,453
-0.2
1978
5,219
5,210
-0.2
1979
9,797
9,789
-0.1
1980
7,585
7,567
-0.2
1981
4,080
3,965
-2.8
1982
6,453
6,432
-0.3
1983
9,121
9,130
0.1
1985
4,885
4,850
-0.7
1986
3,845
3,835
-0.3
1987
4,934
4,924
-0.2
1988
3,866
3,798
-1.8
1989
6,792
6,908
1.7
1990
5,582
5,559
-0.4
1993
6,124
6,104
-0.3
1994
9,836
9,821
-0.2
1996
6,956
6,956
0.0
1997
7,192
7,185
-0.1
1998
7,887
7,891
0.1
1999
4,431
4,423
-0.2
2000
4,063
4,073
0.3
Duke Energy Carolinas, LLC 37 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

Year
April - December Average Flow Releases (cfs)
Percent Difference
Compared to
Existing Operations
Existing Operations
(BaseProjected_2012 -08-
23 73 r)
Proposed Operations
(B1end2Db_v2_73yr)
2001
3,815
3,789
-0.7
2002
3,772
3,760
-0.3
2003
9,466
9,483
0.2
2004
7,472
7,487
0.2
2006
4,153
4,135
-0.4
2007
3,883
3,984
2.6
2008
3,686
3,686
0.0
2009
5,776
5,174
-10.4
2010
4,930
4,915
-0.3
2011
4,348
4,328
-0.5
Drought Year Average Percent Difference
Drought Year Minimum Percent Difference
Drought Year Maximum Percent Difference
-0.6%
-13.4%
2.0%
Duke Energy Carolinas, LLC
38 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

Table A -2. April - December Average Keowee Hydro Station Flow Releases for
Drought Years (Projected Withdrawals with Historical Hydrology)
Year
April - December Average Flow Release (cfs)
Percent Difference
Compared to
Existing Operations
Existing Operations
(BaseProjected_2012 -08-
23 73 r)
Proposed Operations
(B1end2Db v2_73yr)
-
1940
928
898
-3.2
1941
600
619
3.3
1942
936
921
-1.6
1944
831
830
-0.2
1945
845
841
-0.5
1946
945
946
0.1
1947
715
676
-5.5
1951
850
846
-0.5
1952
758
753
-0.7
1953
930
925
-0.5
1954
683
481
-29.7
1955
633
541
-14.6
1956
645
642
-0.4
1957
1,126
1,093
-2.9
1958
973
971
-0.2
1959
1,177
1,154
-2.0
1962
907
877
-3.4
1963
655
642
-2.0
1966
817
816
-0.1
1968
791
782
-1.0
1970
607
587
-3.2
1971
1,015
1,002
-1.2
1978
502
489
-2.6
1979
1,540
1,534
-0.4
1980
863
854
-1.1
1981
555
439
-20.9
1982
795
779
-2.0
1983
882
891
1.0
1985
602
581
-3.6
1986
374
355
-4.9
1987
567
440
-22.4
1988
465
352
-24.4
1989
769
940
22.2
1990
628
623
-0.8
1993
711
630
-11.3
1994
1,045
1,032
-1.3
1996
798
785
-1.7
1997
643
643
0.0
1998
660
659
-0.0
1999
379
238
-37.1
2000
444
354
-20.3
2001
189
189
0.2
2002
314
302
-3.8
2003
1,141
1,142
0.1
2004
1,130
1,135
0.5
Duke Energy Carolinas, LLC 39 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

Year
April — December Average Flow Release (cfs)
Percent Difference
Compared to
Existing Operations
Existing Operations
(BaseProjected- 2012 -08-
23 73yr)
Proposed Operations
(B1end2Db v2_73yr)
—
2006
578
393
-31.9
2007
514
364
-29.2
2008
266
314
17.7
2009
479
614
28.3
2010
613
480
-21.7
2011
664
467
-29.8
1996
798
785
-1.7
1997
643
643
0.0
1998
660
659
-0.0
1999
379
238
-37.1
2000
444
354
-20.3
2001
189
189
0.2
2002
314
302
-3.8
2003
1,141
1,142
0.1
2004
1,130
1,135
0.5
2006
578
393
-31.9
2007
514
364
-29.2
2008
266
314
17.7
2009
479
614
28.3
2010
613
480
-21.7
2011
664
467
-29.8
Drought Year Average Percent Difference
Drought Year Minimum Percent Difference
Drought Year Maximum Percent Difference
-5.3
-37.1
28.3
Duke Energy Carolinas, LLC
40 401 WQC Application
Keowee - Toxaway Project (FERC no. 2503)

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