20080915 Ver 3_Request for Consultation_NCWRC Comments_20160718

Bridgewater (Lake James)
Reservoir Level Monitor
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Commented [CG1]: The location of the USGS gage and
WQ monitor (items 2 and 3 on the map) are incorrect.
They should be shown at the first bridge crossing
below the powerhouse.
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Also the distance downstream (in the table below)
should be 0.15 for locations 2 and 3.
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USGS 02136520 CATAWBA R AT SR1223 BL LK JAMES NR BRIDGEWATER, NC
roaro„ may co
Burke County, North Carolina
Hydrologic Unit Code 03050101
Latitude 35°44'25.3", Longitude 81°50'04.8" NAD83
Drainage area 38b.261 square miles
Gage datum 1,056.7 feet above NAVD88
Device Location Rationale
The ring -jet valve at the Catawba Dam is designed to supply seasonal minimum continuous
Minimum
Approximate
USGS Satellite
Map
Downstream of
Recommended
Distance
Link to NWISt
2
Location
Data
Location
Downstream
Comments
Data Collection
West Bank of
—
(miles)
and Turbine
Flows
Linville River
Generation
Wireless
Project Hourly
Bypassed
Records
telemetry to
1
Reach Minimum
Catawba Dam
n/a
Flow sensor at
Flow Release
Hydro Station
Continuous
Wireless
Computer and
Flows
Valve
Staff Gage for
Water
Downstream of
In Situ - Pipe and
to Hydro Station
visual
Device Location Rationale
The ring -jet valve at the Catawba Dam is designed to supply seasonal minimum continuous
Minimum
USGS Satellite
Continuous
Flows
Downstream of
Link to NWISt
2
Recreational
Powerhouse,
0.195
USGS Station
Web Interface
West Bank of
—
02138520
and Turbine
Flows
Linville River
Generation
Project Hourly
Records
Flows
Wireless
Telemetry (DO)
Water
Downstream of
In Situ - Pipe and
to Hydro Station
3
Temperature,
Powerhouse,
0.195
Instruments
Computer,
DO
West Bank of
USGS Station
n
USGS Satellite
Linville River
02138520
Link to NWIS
Web Interface
Bridgewater
Current Device on
Wired to Hydro
4
Reservoir Levels
Forebay
n/a
the Intake
Station
Structure
Computer
Device Location Rationale
The ring -jet valve at the Catawba Dam is designed to supply seasonal minimum continuous

flows in the Catawba River Bypassed Reach (Location 1). A sensor, calibrated for flow,
provides a continuous reading of the flow being released into the Catawba River Bypassed
Reach. Since the sensor is located on the dam, it should be secure from vandals.
The channel configuration at USGS Gage 02138520, CATAWBA R AT SR1223 BL LK JAMES
NR BRIDGEWATER, NC, located 0.185 mile below the Bridgewater Powerhouse, is ideally
suited for the expected range of flows originating from the Linville Dam (Location 2 & 3). The
site is located on private property providing a measure of security.)
- -
commented [CGz]: Not sure what you mean; this site
_
A previous water quality monitoring site was located on the downstream side of the former
is wide open to the public. The USGS gage is shown
as occurring immediately below the bridge at the
Bridgewater Powerhouse. Given the present configuration of the new Bridgewater Powerhouse,
fishing pier. See screen capture from USGS. So,
a decision was made to place the water quality monitoring instrument at the existing USGS flow
either USGS information is incorrect, or you are
describing a different site altogether.
gage station. Additional downstream continuous DO monitoring conducted in 2012 for aeration
characteristics of the new Bridgewater Powerhouse generating units demonstrated that at the
existing USGS gage site, DO concentrations were virtually identical to those measured
simultaneously at the previously proposed (WQMP version 0) site, which was located 0.05 miles
further downstream at the Powerhouse Road Bridge (HDR 2012). The selected USGS gage site
has been shown to represent the water quality conditions of any combination of hydro unit flow
(including minimum flow). In addition, the site is accessible under all Project flows, and will
facilitate a rapid response at the station to water quality conditions. This gage site, originally
installed in December 2008, was upgraded by the USGS in August 2015 to accommodate
seasonally operated water quality instrumentation. Security from vandals is a minor concern at
this site. Besides seasonal compliance monitoring for generation flow DO, water temperature
will be monitored seasonally at this site to support state trout management initiatives on the
downstream section of the river.
I National Water Information System: Web Interface operated by the USGS.

Oxford (Lake Hickory)
Map
Location
Data
Recommended
Location
Approximate
Distance
Downstream
(miles)
Comments
Data Collection
Planned USGS
Station with In Situ
Wireless
Highway 16
- Pipe and
Telemetry (DO)
Water
Bridge
Instruments
to Hydro Station
1
Temperature,
Downstream of
0.15
Mounted on
Computer,
DO
Oxford Hydro
Bridge, South
USGS Satellite
Channel
Link to NWIS
(NCDOT approval
Web Interface
required)

2
Minimum
Continuous
Flows
Oxford Dam
n/a
Modified Trash
Gate monitored
via Reservoir
Elevation and
Gate Position
Wired to Hydro
Station
Computer
Reservoir level will be monitored during trash gate spillage to assure compliance with the
minimum continuous flow.1_Generation and recreational flow requirements will be recorded from
, -
commented [cGs]:It is not clear how this approach
Wireless
will ensure that 150 is provided over a range of
lake levels. Will the ttrash gate be calibrated?
ra
placed at the boat put -in at Riverbend Park (Location 3) for independent verification.
Automated?
Telemetry to
I suggest adding some text explaining how the gate
wingwall. That site adequately represented the water quality of the turbine flow when all the
will operate and provide continuous minimum flow.
Hydro Station
Recreational
Highway 16
Computer,
Flows
Bridge
USGS-Level
and/or USGS
3
Project Hourly
Downstream of
0.15
Monitor
Satellite Link to
Flows
Oxford Hydro,
NWIS Web
Turbine Records
Interface (Level),
and Turbine
Generation
Records
Current Device on
Wired to Hydro
4
Reservoir Levels
Oxford Forebay
n/a
the Intake
Station
Structure
Computer
Device Location Rationale
An existing trash gate will be modified to spill well-aerated reservoir near -surface water in order
to provide a constant minimum continuous flow in the downstream channel (Location 2). The
gate will provide the minimum continuous flow during periods of no hydro unit generation.
Reservoir level will be monitored during trash gate spillage to assure compliance with the
minimum continuous flow.1_Generation and recreational flow requirements will be recorded from
, -
commented [cGs]:It is not clear how this approach
------------------
the generation records for each turbine. A manually read, USGS-type plate staff gage will be
will ensure that 150 is provided over a range of
lake levels. Will the ttrash gate be calibrated?
ra
placed at the boat put -in at Riverbend Park (Location 3) for independent verification.
Automated?
A previous water quality monitoring site was located in the corner of the Oxford Powerhouse and
I suggest adding some text explaining how the gate
wingwall. That site adequately represented the water quality of the turbine flow when all the
will operate and provide continuous minimum flow.
hydro units were identical, and prior to the installation of the tailrace buttresses. However, this
site now is not representative of the combined flows from hydro units with differing aeration
capability and the buttresses would effectively prevent Unit 2 water from reaching the sensor
when Unit 1 is generating. Therefore, a decision was made to move the monitor to the Highway
16 Bridge immediately downstream of the turbines (Location 1). The bridge not only provides an
existing structure to place the water quality monitor in the channel, but this site will represent the
water quality conditions of any combination of hydro unit flows. This site will be accessible under
all Project flows, and will provide a rapid response of the station to water quality conditions.
Security from vandals may be a concern at this site, and adverse effects on equipment due to
occasional high tailwater water levels is a possibility.

3.0 Supplemental Trout Habitat Monitoring
3.1 Monitoring
The Catawba River Bypassed Reach and Bridgewater minimum continuous flows have been
selected and evaluated to provide flows and water temperatures suitable for protection and
enhancement of mussels in the bypassed reach and the maintenance of a stocked trout fishery
downstream of Bridgewater Hydro. The volume of warmwater flows provided to the Catawba
River Bypassed Reach to maintain mussel habitat are balanced against the coldwater minimum
flow from the Linville Dam to maintain suitable temperatures for trout downstream of the
confluence of the Catawba River Bypassed Reach and the Linville River. During Project
relicensing, the flows and temperatures provided to each channel to achieve the desired, but
conflicting temperature requirements were analyzed by the CE -QUAL -W2 reservoir model and
the River Modeling System (RMS). The results of these computer models were evaluated by the
Aquatics/Terrestrial and Water Quality Resource Committees. Bypassed Reach and Linville
Dam minimum continuous flows stated in the CRA are the result of the recommendations from
the evaluations by the resource committees.
Due to the hydraulic complexity and trout supplemental management interests in this area,
supplemental monitoring will be used seasonally (1 April through 30 November) to support
future evaluations of whether trout management goals in the mainstem Catawba River continue
to be supported. Results of this monitoring may be used to determine if flow reductions need to
be made in the Catawba River Bypassed Reach.
Per CRA agreement, this supplemental trout habitat monitoring was to commence after the
Bridgewater Powerhouse had been replaced with either a new powerhouse or valve system and
compliance operations had begun. Also, the study was to continue through the next full North
Carolina Division of Water Resources (NCDWR) Catawba River Basinwide Assessment period,
but not beyond Year 2019. Due to the extended time between the CRA signing and New
License issuance, Duke Energy and the NCDWR have agreed that the study will be conducted
at least from 2016 to 2019 (four years), but may be extended to additional years if the initial four
sampled years are not sufficiently variable from either a meteorological or operational
perspective.
The general study outline for the supplemental trout habitat monitoring is provided below.
3.2 Sensor Locations
The temperature and level logger placement is designed to be able to record temperatures, flow
(level logger with stage -discharge relationship) from the inflows, and empirically determine the
temperatures at the appropriate downstream river reaches. An additional downstream
temperature and level logger and staff gage (not depicted on the map below) will be provided at
the Watermill Bridge (RM 271.7) in Glen Alpine, NC which is in the middle of the primary trout
habitat.

Bridgewater Supplemental Trout Habitat Monitoring
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Reservo!r Level
Temperature'
M:grtitaE? ` USGS Gage & WQ '
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Logger, Level
Monitor (Compliance)
rk
Logger, & Staff <>
Gage y
Valve Flow
Monitor Temperature
- (Compliance) Loggers
Temperature /
Loggers
z Level Logger, -
Staff Gage
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3.3 System Requirements
Level loggers (devices to record river stage from which a stage -discharge relationship may be
developed to calculate flow) and temperature loggers will be placed in the river and periodically
downloaded to obtain the respective data. Stage -discharge curves will be developed and
maintained for the level logger sites.
3.4 Reporting Requirements
Annual reports will be provided to the NCDEQ and North Carolina Wildlife Resources
Commission (NCWRC) annually by 30 April, the calendar year following monitoring seasons, for
the duration of the supplemental trout habitat monitoring study. Reports will detail the previous
monitoring season's temperatures and levels. Flow -weighted temperatures will be calculated
for the downstream sites.
Commented [CG4]: Same comment as above re:
i
location of USGS gage.
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