NC0038377_Monitoring (Report)_20190725

DUKE
ENERGY,
PROGRESS
File Point: 12520 M
Ms. Cyndi Karoly,
Chief, Water Scien It s Section
Division Water Re. o ices
NC Division of Environmental Quality
1621 Mail Service Center
Raleigh, North Carolina 27699-1621
July 25, 2019
Subject: Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Dear Ms. Karoly:
Mayo Steam Plant
Duke Energy Progress
10660 Boston Road
Roxbolo. NC 27574
{1
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0.
or P
00
Please find enclosed two copies of the Mayo Steam Electric Plant's 2018 Environmental Monitoring Report. The
report summarizes the results of the monitoring program required by the power plant's NPDES Permit
NC0038377.
During 2018, operational effects of the Mayo Steam Electric Plant on the water quality and aquatic life continued
to be minimal. Selenium concentrations in reservoir surface waters were near or below lower reporting levels.
Selenium concentration in the muscle tissues of Largemouth Bass, BluegiIl, and Catfish declined compared to
muscle tissue concentrations measured during 2013, 2014, 2015, 2016 and 2017. Boron concentrations declined
throughout the reservoir with operation of the thermal evaporator treatment system. The reservoir continued to
support a healthy aquatic community. The fish community continued to be dominated by Bluegill and
Largemouth Bass. Strong reproduction of both species was evident throughout the reservoir and results indicate
balanced fish populations.
1 cerrifi•, tinder penalty of law, that this doctotnent and all attachments here prepared under my direction or
supers-ision in accordance srith a s'vstetn designed to assure that qualified personnel property gather card
evaluate the infornnatiotr .submitted. Based on tun' inquiry of the person or personns who utanage the system,
or those persons directly responsible for gathering the information, the information submitted is, to the Best
of my kno►vledge and belief, true, accurate, and complete. 1 ant a►vare that there are significant penalties for
submitting false information, including the possibility of fees and imprisonnietit for knowing violations.
If you have any questions about the 2018 Environmental Monitoring Report or need further information, please
contact Mr. Jason Green, Environmental Sciences Section, at 919 546-6318.
LPW/lpw
Enclosures
c: Mr. Christian Waters — NCWRC
mr, rZccK Sol=cJk\.- McDM
PC VEA Ce.c i mi F, les
Sincerely,
Tom Copolo
Manager
Mayo Steam Electric Plant

MAYO STEAM ELECTRIC PLANT
2018 ENVIRONMENTAL MONITORING REPORT
May 2019
Water Resources Unit
Environmental Sciences Section
Duke Energy Progress, LLC.
Raleigh, North Carolina
�> DUKE
ENERGY:

This copy of the report is not a controlled document as detailed in the Biology Program Procedures
and OtralitvAsmirance Xfanual. Any changes made to the original of this report subsequent to the
date of issuance can be obtained from:
Director
Environmental Sciences Section
Duke Energy Progress, LLC.
410 S. Wilmington St.
Raleigh, North Carolina 27602

Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Table of Contents
ExecutiveSummary....................................................................................
1
Introduction...
2
2 Objectives and Methods........................................................................
2
3 Key Indicators of May Reservoir Environmental Quality During 20I8.....................
9
3.1 Limnology........ .........................................................................
9
3.1.1 Temperatu and Dissc Ived Oxygen ......................................................
9
3.1.2 Water Clari y.....................................................................
9
3.1.3 Nutrients and Chlorophyll a ...........................................................
9
3.1.4 Specific Conductance, Ions, Hardness and Alkalinity .........................
10
3.1.5 Comparison of Limnological Variables Along Transect B....................
10
3.2 Trace Elements....................................................................................
10
3.2.1 Arsenic................................................................................
10
3.2.2 Cadmium.............................................................................
I0
3.2.3 Copper................................................................................
11
3.2.4 Mercury...............................................................................
11
3.2.5 Selenium..............................................................................
11
3.2.6 Additional Trace Elements.........................................................
12
3.3 PhytopIankton..................................................................................
12
3.4 Biofouling.....................................................................................
13
3.5 Aquatic Vegetation
...........................................................................
I3
3.6 Fisheries.......................................................................................
13
3.6.1 Species Composition
...............................................................
13
3.6.2 Relative Abundance and Size Structure ..........................................
14
4 Conclusions..........................................................................................
14
5 References.............................................................................................
16
List of Tables
2.1 Mayo Reservoir Environmental Monitoring Program for 2018........................... 6
2.2 Field Sampling and Laboratory Methods Followed in the 2018 May Reservoir
Environmental Monitoring Program......................................................... 7
2.3 Statistical Analyses Performed on Data Collected in the 2018 May Reservoir
Environmental Monitoring Program......................................................... 8
List of Figures
2.1 Mayo Reservoir Sampling Locations during 2018......................................... 5
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
List of Appendices
A
Depth profiles of water temperature at Mayo Reservoir during 2018.
A-1
B
Depth profiles of the water temperature, dissolved oxygen, pH, and specific
conductance at Mayo Reservoir during 2018.
A-2
C
Concentrations of limnological variables, measured in the surface waters of Mayo
Reservoir during 2018.
A-3
D
Concentrations of limnologica I variables i neasured in the surface waters of Mayo
Reservoir during 2018.
A-6
E
Spatial trends of means and rajiges for selected Iimnological variables from
surface waters of Mayo Rese oir at Stations B2, E2, and G2 during 2018.
A-9
F
Long-term trends of means for selected limnological variables from surface
waters of Mayo Reservoir at Stations B2, E2, and G2, 2005-2018.
A-I0
G
Spatial trends of means and ranges for selected limnological variables from
surface waters of Mayo Reservoir along Transect B during 2018.
A-12
H
Means and ranges of trace element concentrations in the sediments and left axial
muscle tissues of fish from Mayo Reservoir during 2018.
A-13
I
Annual mean trace element concentrations measured in sediments collected from
station Bl in Mayo Reservoir, 2005-2018.
A-14
J
Annual mean selenium concentrations measured in the left axial muscle tissue of
catfish collected from Transects B, E, and G in Mayo Reservoir, 2005-20 i 8.
A-14
K
Annual mean selenium concentrations measured in the left axial muscle tissue of
Bluegill collected from Transects B, and G in Mayo Reservoir, 2005-2018.
A-I5
L
AnnuaI mean selenium concentrations measured in the left axial muscle tissue of
Largemouth Bass collected from Transects B, and G in Mayo Reservoir, 2005-
2018.
A-15
M
Total number and total weight of fish collected from Mayo Reservoir with
electrofishing sampling during 2018.
A-16
N
Mean number per hour for fish collected with electrofishing sampling by transect
from Mayo Reservoir during 2018.
A-1 7
O
Length -frequency distribution of Gizzard Shad collected with electrofishing
sampling from Mayo Reservoir during 2018.
A-18
P
Long-term annual mean electrofishing catches for Bluegill, Largemouth Bass,
Redear Sunfish, and Gizzard Shad collected from Mayo Reservoir, 2005-2018.
A-18
Q
Length -frequency distributions of Bluegill by transect collected with
electrofishing sampling from Mayo Reservoir during 2018.
A-19
R
Length -frequency distributions of Bluegill by year collected with electrofishing
sampling from Mayo Reservoir, 2014-2018.
A-20
S
Relative weight values of Bluegill, Largemouth Bass, and Redear Sunfish
collected with electrofishing sampling from Mayo Reservoir during 2018.
A-21
T
Length -frequency distributions of Largemouth Bass by transect collected with
electrofishing sampling from Mayo Reservoir during 2018.
A-22
U
Length -frequency distributions of Largemouth Bass by year collected with
electrofishing sampling from Mayo Reservoir, 2014-2018.
A-23
V
Mean annual relative weight values for Largemouth Bass by year collected with
electrofishing sampling from Mayo Reservoir, 2005-2018.
A-24
W
Proportional size distributions of Largemouth Bass by year collected with
electrofishing sampling from Mayo Reservoir, 2005-2018.
A-24
X
Length -frequency distributions of Redear Sunfish collected with electrofishing
sampling from Mayo Reservoir during 2018.
A-25
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Metric -English Conversion and Units of Measure
Length
I micron (µm) = 4.0 x I V inch
I millimeter (mm) — 1000 µm — 0.04 inch
centimeter (cm) = 10 mm - 0.4 inch
1 meter (m) = 100 cm = 3.28 feet
1 kilometer (km) = 1000 m = 0.62 mile
Area
I square meter (m) = 10.76 square feet
I hectare (ha) = 10,000 m' = 2.47 acres
Volume
I milliliter (ml) = 0.034 fluid ounce
I liter = 1000 ml = 0.26 gallon
I cubic meter = 35.3 cubic feet
Weight
1 Micrc gram (µg) = 10-3 mg or
10-' = 3.5 x 10' ounce
1 milli ram (mg) = 3.5 x 10'5 ounce
I gram (g) = 1000 mg = 0.035 ounce
I kilogram (kg) = 1000 g = 2.2 pounds
1 metric ton = 1000 kg = I .l tons
I kg/hectare = 0.89 poundlacre
Temperature
Degrees Celsius (IC) = 5'9 (°1:-32)
Specific conductance
µStem — Microsiemens;'centimeter
Turbidity
NTU = Nephelometric Turbidity Unit
Water Chemistry Abbreviations
Cl-
- Chloride
NH3-N - Ammonia nitrogen
S02
- Sulfate
TP -
Total phosphorus
Ca'-+
- Total calcium
TOC -
Total organic carbon
Mg-'+
- Total magnesium
TS -
Total solids
Na'
- Total sodium
TDS -
Total dissolved solids
TN
- Total nitrogen
TSS -
Total suspended solids
NO3' + NO2' - Nitrate + nitrite
Al -
Total aluminum
MO
- Total molybdenum
TI -
Total thallium
As
- Total arsenic
Cd
- Total cadmium
Cu
- Total copper
Hg
- Total mercury
Se
- Total selenium
B
- Total boron
Co
- Total cobalt
Sb -
Total antimony
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Executive Summary
During 2018, Mayo Reservoir continued to support an aquatic community typical for an
oligotrophic impoundment in the southeastern United States. The relatively small watershed, low
water inflow, and limited shoreline der lopment within the watershed have influenced the amouni
of nutrients entering the reservoir and the subsequent biological productivity. Productivity, as
measured by chlorophyll a, was low ovrall and reflected the nutrient -limited conditions present
in the reservoir.
Operational effects of the Mayo Steam Electric PIant on ecological conditions in Mayo Reservoir
continued to be minimal during 2018. Concentrations of total dissolved solids, boron, chloride,
hardness, and specific conductance have all exhibited declines since operation of the thermal
evaporator system for FGD wastewater began during early 20I5. Concentrations have reached
pre-FGD levels, and are expected remain at this level or continue to decline in the future.
The concentrations of surface water trace elements measured in the lower reservoir were greatest
at Station B1 near the ash basin discharge. All concentrations for these variables were Iess than
the applicable North Carolina water quality standards or USEPA national criteria at all stations
sampled in the lower reservoir. All selenium concentrations measured in the surface waters of
Mayo Reservoir were close to, or below reporting limit during 2018.
Consistent with previous years, results indicate that trace element input to the reservoir was
restricted to the immediate vicinity of the wastewater discharge. Trace metals concentrations in
sediments have been in overall decline since 2014 at Station B 1. No accumulation of arsenic in
Fish tissues was evident at Station B I or any other location sampled in the reservoir during 2018.
This trend indicates that arsenic is not biomagnified up the food chain, in a similar fashion as
selenium. Greater concentrations of selenium were detected in fish tissue samples collected from
the vicinity of the ash basin discharge compared to the upper reservoir during 2018. Selenium
concentrations measured in all fish tissue samples decreased when compared to elevated values
measured during 2012 and 2013. Sustained decline of selenium concentrations in fish tissues is
expected with continued operational use of flue gas desulfurization (FGD) and wastewater thermal
evaporator systems.
Species dominance and distributional patterns within the fish community during 2018 were
similar to results from previous years. The fish community in Mayo Reservoir continues to be a
sunfish -dominated community with Bluegill remaining the dominant species. A strong Gizzard
Shad forage base was evident as well. While some selenium accumulation was evident in fish
tissues, there was no evidence of an adverse effect to the fish community, species composition or
reproduction. Abundance of selenium tolerant species such as Green Sunfish remained low and
most individuals were collected only at locations containing their preferred shoreline -rip -rap
habitat. BluegiIl and Largemouth Bass were collected throughout the reservoir and there were
no adverse trends in the abundance of either species over the last fourteen years. Successful
reproduction of Bluegill and Largemouth Bass was evident throughout the reservoir with no
indication of any missing year classes. Length distributions and proportional size density indices
for Largemouth Bass indicated a balanced population, and fish sampled exhibited healthy and
relatively robust body condition. No disease outbreaks or fish kills were noted during 2018
providing additional evidence of a healthy fish community.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
I. Introduction
Mayo Reservoir, located in Person County, North Carolina, is an impoundment of Mayo Creek, a
tributary of the Roanoke River (Figure 2.I). Mayo Reservoir has a surface area of 1,133 hectares
and an average retention time of 36 months. The reservoir was constructed to provide make-up
cooling water for the Mayo Steam Electric Plant cooling towers and receives some plant process
waste -waters via a National Pollutant Discharge Elimination System (NPDES) permitted outfall
(Permit # NC0038377, outfall # 002). The wat r hed is characterized by rolling hills with 55%
forest, 18% agriculture, 4% residential developmei it, and less than I % as impervious cover (USGS
2012). Geologic formations in the watershed of f 4ayo Reservoir include several copper bearing
mineral deposits (NCDENR I976). A buffer zone along the entire shoreline perimeter was created
due to initial environmental requirements. Mayo Reservoir receives extensive recreational use
(boating, fishing, hunting), The Mayo Lake County Park and public boat ramp is located
approximately mid -way up the reservoir from the power station. The reservoir currently has a
WS-V water quality classification and served as a source of drinking water for the station
employees until 2007 when municipal water was supplied to the station.
Mayo Reservoir is typically characterized by lo« to moderate biological productivity
(Wetzel 1975). The most recent assessment conducted by the North Carolina Division of Water
Resources (NCDWR) during 2014 determined a trophic state index classification of oligotrophic
for the reservoir (NCDWR 2014). The fish community is dominated by shad and sunfishes.
Significant recreational fisheries exist for Bluegill, Redear Sunfish, Black Crappie, Largemouth
Bass, and Chain Pickerel. A few non-native species have become established in Mayo Reservoir
since initial impoundment, but no adverse effects have been observed with the existing shad and
sunfish species. Brazilian elodea, Egeria clensa, and Asian clam, Corbicula fluminea, were
introduced during 1984 and rapidly colonized the entire reservoir. Hydrilla, Hydrilla verlicillala,
became established at the public boat ramp during 1989 and slowly spread throughout the reservoir
displacing Brazilian elodea as the dominant aquatic vegetation by the early 2000's. No power
plant operational issues have resulted from the presence of either species.
Mayo Steam Electric Plant began commercial operation in 1983 when the reservoir reached
full -pool elevation. Environmental monitoring of the water, sediments, and aquatic organisms in
Mayo Reservoir has been conducted since then. This monitoring program was conducted to meet
requirements specified in the NPDES Permit issued by the NCDWR. Annual environmental
monitoring reports that characterize and describe the aquatic community of Mayo Reservoir have
been published since 1984 with the most recent results detailed in DEP 2013, 2014, 2015, 2016,
2017; PEC 2009, 2010, 2011, 2012. These reports describe changes to chemical and physical
water quality in Mayo Reservoir in response to power plant operational changes, wastewater
treatment system modifications and ash basin improvements. Effects of the power plant discharges
on the water and aquatic organisms in Mayo Reservoir have been minimal and have been confined
primarily to the area nearest the ash basin discharge. The reservoir has continued to support a
biological community typical of an oligotrophic (nutrient -limited) southeastern reservoir
(NCDENR 2014). No significant negative impacts to the aquatic community as a result of the ash
basin discharge have been observed in Mayo Reservoir in over three decades of monitoring.
2. Objectives and Methods
The primary objective of the 2018 Mayo Steam Electric Plant environmental monitoring
program was to provide an assessment of the effect of power plant operations on the water and
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
aquatic organisms in Mayo Reservoir. Secondary objectives of the program were to document
other environmental factors impacting the aquatic community and the impact of introductions of
nonnative aquatic plant and animal species into the reservoir.
Key indicators of the environmental quality of Mayo Reservoir (i.e., water quality, water
chemistry, phytoplankton, fisheries, and trace elements) were assessed at designated locations in
he reservoir (Table 2.1 and Figure 2.1). Sampling methods, data summaries, and statistical
nalyses For data collected during 2018 were similar to methods used in previous years (Tables 2.2
d 2.3). Field and laboratory practices used to obtain assessment data followed approved
ocedural guidelines as described in the Duke Energy Biology Program Quality Assurance
anual (DEP 2012).
Historical data is evaluated in conjunction with data collected during 2018. Water column
trace element data (arsenic, boron, copper, cadmium, mercury, manganese, molybdenum, thallium,
antimony, and selenium) were evaluated from 2005 through 2018 to assess effects from potential
ash basin inputs and operation of the thermal evaporator wastewater treatment system (DEP 2017).
Annual mean selenium concentrations in the left axial muscle tissue of fish were also evaluated
from 2005 through 2018. Selected water chemistry variables were trended from 2005 through
2018 to provide additional insight regarding changes in reservoir water chemistry over time as
influenced by naturally occurring changes or station operations.
Selected fisheries catch and length data from previous years are presented to comparatively
assess fish populations. Length -frequency distributions of the dominant species for the most recent
five years were shown to document successful reproduction and the presence of multiple size
classes. Long-term annual mean electrofishing catch rates for the numerically dominant sunfish
species, (Largemouth Bass, Bluegill, Redear Sunfish, and Gizzard Shad) were compared across
years, 2005-2018 to determine if any adverse trends in abundance were evident. Annual mean
electrofishing catch data were displayed using a Iogio transformation to enable inclusion oftrend
lines for all four species on one graph.
Largemouth Bass represent a primary indicator species regarding bioaccumulation of
selenium levels associated with reproductive impairment. Two additional variables were
assessed over time as indicators of the health of Largemouth Bass population. Mean annual
relative weight (Wr) values provided an assessment of body condition where optimal values
approach 100 (Wege and Anderson 1978). Proportional Size Distribution (PSD) is a numeric
index related to the length -frequency distribution of Largemouth Bass and was used to provide
an additional assessment of population dynamics (Gablehouse 1984). Analytical analysis of
water samples collected in support of the Mayo Plant environmental program were performed by
North Carolina certified laboratories. Analysis of water chemistry samples collected during 2018
was conducted by PACE Analytical Services (NC DEQ/DWR Wastewater Laboratory
Certification Program, Certificate # 12) following approved methodology. Processing of trace
element sediment and fish muscle tissues was conducted in accordance with Duke Energy
Biology Program Procedures NR-00095 and 00107. Analysis of these samples was conducted
by PACE Analytical Services. The accuracy and precision of laboratory analyses of water
chemistry and trace element data were determined with analytical standards, sample replicates,
and reference materials. Quality assurance information including the accuracy and percent
recovery of water chemistry and trace element standards is available upon request. For
calculation of means in this report, concentrations of less than the laboratory reporting limit were
assumed to be at one-half the reporting limit. Additional water chemistry analytes were added
during 2010 to assess potential scrubber wastewater effects. Antimony, boron, cobalt, cadmium,
mercury, molybdenum, and thallium were added to arsenic, copper, and selenium previously
present in annual study plans.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Data summaries and appropriate statistical analyses were used to describe and interpret the
environmental quality of the reservoir (Table 2.3). Where statistically significant results were
reported, a Type I error rate of 5% (P < 0.05) was used and Fisher's protected least significant
difference test was applied to determine where significant differences in mean values occurred.
In some cases, statistical differences were detected for datasets, but the difference in the means
were so small as to have no biological significance.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
I
YfRGrUTA
N
0 0.5 1 2 Miles
0 0.75 1.5 3 K I meters
f
Sampling Locations:
O Water Quality
Water Chemistry
Electrotishing 4D
Transects
0.
Mayo Steam
Electric Plant
NORTH CAROLINA
Mayo
.. hw
outfall
002
i Bt.
ear
A —Wm
.k r
Boat Ramp
W Son ChaP� Church ¢ti
ti
Figure 2.1 2018 Mayo Reservoir sampling locations.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Table 2.1 Mayo Reservoir environmental monitoring program for 2018.
Program Frequency Location
Water quality
February, April, June, August,
October December_
Water chemistry
Febru April, June, August,
October December_
Phytoplanktoni
February, April, June, August,
October, December
Biofouling monitoring
Zebra and quagga mussel February, April, June, August,
surveys October, December
Stations B1, B2, B3, E2, and G2
surface -to bottom at 1-m intervals) I
Stations B1, B2, B3, E2 and G2
Stations B2, E2, and G2
Intake structure or water quality station
Fisheries
Electrofishing April, May, October, Stations BI, B3, E1, E3, GI, and G3
November
Trace elements — -
April, May Stations BI and B3; Area G
Aquatic vegetation survey
September, October Areas B, E, F, G, and H
'Plankton included sampling for phytoplankton (algae) and chlorophyll a. Since all chlorophyll a concentrations
were below 40 µr* , phytoplankton samples collected and preserved during the bimonthly sampling were not
identified.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Table 2.2 Field sampling and laboratory methods followed in the 2018 Mayo
Reservoir environmental monitoring program.
Program Method
Water quality Temperature, dissolved oxygen, pH, and specific conductance were measured with
calibrated multiparameter in truments. Measurements were taken from the surface
to the bottom at 1-m intervals in accordance with procedure NR-00096 Water cl ity
was measured with a Secchi dish. Turbidity was measured with a HACH model
2100Q turbidim ter in accordance with procedure WR-00070
Water chemistry Surface samples were collected either directly or with a nonmetallic sampler,
transferred to appropriate containers, transported to the laboratory on ice, and
analyzed according to USEPA (1979) and APHA (1995).
Phytoplankton Representative photic zone composite samples were collected from the surface to
twice Secchi disk transparency depth using an integrated depth sampler. Samples
were placed in 250-ml containers and preserved with 5 ml of "MY fixative as
described in Procedure NR-00072, Rev. 1.
Chlorophyll a Representative photic zone composite samples were collected from the surface to
twice Secchi disk transparency depth using an integrated depth sampler. The samples
were placed in dark bottles, and transported to the laboratory on ice. In the laboratory,
250-ml subsamples were analyzed following procedure NR-00103.
Mussel surveys A water quality monitoring station buoy was visually inspected for the presence of
zebra mussels and quagga mussels during routine water quality monitoring (Claudi
and Mackie 1993).
Electrofshing Fifteen -minute samples were collected at each station using a Smith -Root Type
7.5 gpp. equipped, Wisconsin -design electrofishing boat with pulsed DC current.
Fish were identified, measured to nearest mm, weighed to nearest gram, examined
for presence of disease and deformities, and released based on Procedure NR-00080,
Rev. 1. (Page 2013).
Trace elements Water, sediments, and tissues of selected fish were analyzed with standard analytical
techniques by a certified laboratory. Quality control is achieved by analytical
standards, replicates, and certified reference materials. All media except for water
were processed prior to analysis by the DEP Water Resources Laboratory according
to Procedure NR-00107, Rev. 4.
Vegetation survey Portions of each area were surveyed for the presence of nuisance aquatic vegetation.
Qualitative observations were recorded in accordance with Procedure NR-00079,
Rev. 1.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Table 2.3 Statistical analyses performed on data collected in the 2018 Mayo Reservoir
environmental monitoring program.
Program Variable Transfor- Statistical
g mation test/model' Main effect(s)
Water quality Specific conductance and
Secchi disk transparency
Water chemistry Select monitoring
variables
Trace elements Water
None One-way ANOVA
None One-way ANOVA
None One-way ANOVA
Transect, station
Transect, station
Transect, station
Sediment and tissues None One-way ANOVA Transect, station
'Statistical testing was conducted using a analysis of variance (ANOVA) one-way and two-way models. A
significance level of 5% (P :5 0.05) was used to judge the significance of all tests. For the ANOVA models, Fisher's
protected least significant difference (LSD) test was applied to determine where differences in means occurred.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
3. Key Indicators of Mayo Reservoir Environmental Quality
During 2018
3.1 Limnology
3.1.1 Temperature and Dissolved Oxygen
Temperature and dissolved oxyge patterns iI Mayo Reservoir during 2018
were similar to patterns observed in previou years (DEP 2013-2017; PEC
2008- 2012) and was typical o oligotrophic southeastern United States
reservoirs (Wetzel 1975). The reservoir began to stratify during April and
remained well stratified through October. Reservoir waters were well mixed
again by December (Appendix A and C).
Surface water temperature across the reservoir ranged from a low of 6. I'C in February to a
high of 29.1 °C in June. Similar to historic observations, metalimnetic dissolved oxygen
minima were noted for Station B2 during August, and Station E2 during June. The lowest
measured surface water concentrations of dissolved oxygen were observed in August at
Stations E2 and G2 (7.6 mg/L). At no time were dissolved oxygen concentrations in the upper
layer of the water column measured at a level detrimental to aquatic life (Appendix B and C).
3.1.2 Water Clarity
During 2018 Mayo Reservoir exhibited relatively clear conditions with a mean
Secchi depth value of 2.1 meters, and a mean turbidity value of 3.5 NTU
measured at stations B2, E2, and G2. Mean Secchi disk transparency depth and
turbidity values continued to indicate longitudinal trends typical of reservoirs
(Wetzel 1975). The headwater region of the reservoir (Station G2) generally
had the lowest water clarity when compared to the downstream (Station 132)
area near the dam (Appendices D and E). Turbidity was greater in the
headwater regions as compared to the lower reservoir with the exception of one
value of45 NTU, recorded on June 5 at Station B 1. No long-term trends in the
annual mean Secchi disk transparency depth or turbidity were evident
(Appendix F). During 2018, the mean total dissolved solids concentrations
were similar throughout the reservoir (Appendix F). Total dissolved solids
levels have been consistent since 2016, since the thermal evaporator wastewater
treatment system became operational in late 2014.
3.1.3 Nutrients and Chlorophyll a
During 2018, nutrient concentrations in Mayo Reservoir continued to be
relatively low (Appendices D and E). There were no consistent differences in
mean concentrations of nitrogen based nutrients from the lower reservoir
(station 132) to the upper reservoir (station G2). Phosphorous did exhibit a small
but significant difference in mean concentration, between the lower (station B2
and E2) and the upper reservoir (Station G2). Chlorophyll a concentrations
were greater in the upper reservoir (Station G2) when compared to the lower
and middle reservoir (Stations B2 and E2). The annual means of nutrients and
chlorophyll a observed in Mayo Reservoir reflect oligotrophic conditions based
on NCDWR trophic state index calculations (Appendix F).
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Total organic carbon values were similar throughout the reservoir during 2018
(Appendix E),
3.1.4 Specific Conductance, Ions, Hardness, and Alkalinity
With the exception of sodium and alkalinity, significant differences for mean
concentrations of ions, hardness, and spe ific conductance were detected in the
surface waters of Mayo Reservoir dur ng 2018 (Appendix E). The mean
concentrations of most analytes were g ner lly greater in the lower reservoir
(Station 132) although the magnitude of t e differences was relatively small.
The mean annual concentrations of some analytes, primarily boron, chlorides,
total dissolved solids, hardness, and specific conductance, have all sharply
declined after operation of the thermal evaporator treatment system began
during early 2014, and have been consistently low since 2016 (Appendix F).
3.1.5 Comparison of Limnological Variables Along Transect B (Stations B1,
B2, and 133)
No significant differences were detected in the 2018 mean annual
concentrations for all ions, total alkalinity, specific conductance, and boron
along Transect B (Appendix G). Ranges of concentrations during 2018 reflect
similar variability between stations, and lack of localized influence of the ash
basin'scrubber wastewater discharge near Station B 1. Operation of the dry fly
ash handling system as well as the thermal evaporator treatment system have
accounted for reductions in the concentrations of these parameters as previously
observed at Station B 1 (DEP 2017).
3.2 Trace Elements
3.2.1 Arsenic
Arsenic concentrations in surface waters at all stations, including those along
Transect B, were lower than applicable state water quality standards (NCAC
2019). Most were low or below the lower reporting limit with the higher value
of 4.5 µg/L observed at B l during 2018 (Appendices D-G).
Significant spatial differences in mean arsenic concentrations in the sediments
were detected during 2018 (Appendix H). Higher concentrations of arsenic in
the sediments collected from Station B I indicated localized deposition near the
ash basin discharge. Despite the Iocalized higher concentrations, sediment
arsenic concentrations have been in continual decline at station BI since 2014
(Appendix 1).
Arsenic concentrations in all fish tissues were near or below the reporting limits
during 2018 (Appendix H). These results are similar to results from previous
years (DEP 2013, 2014, 2015, 2016, 2017; PEC 2011, 2012) and are important
in that they indicate no significant accumulation of arsenic in fish tissues,
despite some localized deposition of arsenic in the sediments.
3.2.2 Cadmium
Results indicate that cadmium input/accumulation in Mayo Reservoir is not an
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issue and never has been. Cadmium concentrations measured in water,
sediments and fish tissues were less than or near reporting limits during 2018
(Appendices D, E, G, and H) as has historically been the case.
Due to historical non -detectable concentrations of cadmium in the surface
waters monitoring was discontinued after 2001 (PEC 2002). Waterborne
cadmium analysis was added back into the study plan during 2010 at the request
of the North Carolina Division of Environmental ual'ty. Since then, measured
concentrations have consistently been below the re orting limit (DEP 20I3,
2014, 2015, 2016, 2017; AEC 2011, 2012).
3.2.3 Copper
Mean copper concentrations in the reservoir surface waters were near or below
the Iower reporting limit during 20I8 (Appendices D, E, and G). Similar to
previous years, a greater mean concentration of copper was measured in the
sediments collected from the upper reservoir at Transect G during 2018
(Appendix H), reflecting watershed sources of copper (NCDENR 1976).
Concentrations of copper in sediments collected from station B I have been in
decline since 20I4 (Appendix 1).
Copper concentrations measured in Fish muscle tissues wer relatively low or
below reporting limits at all sampling locations during 20I8 (Appendix H).
This is comparable to results reported from previous years indicating no
significant accumulation of copper in fish tissues (DEP 2013, 2014, 2016, 2017;
PEC 2012).
3.2.4 Mercury
Waterborne concentrations of mercury measured in the surface waters of the
main reservoir (Stations B2, E2, and G2) were low or below the laboratory
reporting limit of 0.50 ng/L during 2018 (Appendices D and E). This result was
similar for the mercury concentrations measured in the surface waters along
Transect B including Station B 1 nearest the wastewater outfalI (Appendix G).
Results continue to indicate that mercury accumulation in Mayo Reservoir is
not a concern. Mean mercury concentrations in sediments ranged from 0.04
0.08 mg/kg, while concentrations in fish tissue ranged from 0.1 3.5 mg/kg
(Appendix H). This is slightly lower than concentrations observed in selected
species during 2017 (DEP 2017).
3.2.5 Selenium
Selenium concentrations measured in the surface waters of Mayo Reservoir
were near or below the lower reporting limit (0.5 µg/L) during 2018
(Appendices D and E). The only result not below the reporting limit during
2018 was observed in June at Station B 1, with a concentration of 0.7 µg/L
(Appendices D and G). Long-term trends in the mean annual concentrations of
selenium have been near or below the lower reporting limit since 2013
(Appendix F). These trends are consistent with input reductions associated with
the 2013 switch to dry -fly ash handling and 2014-15 implementation of the
thermal evaporator treatment system.
The mean selenium concentration measured in the sediments at Station B I was
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significantly greater than the mean selenium concentration measured in the
sediments sampled from stations B3, and G (Appendix H). This pattern of
selenium accumulation in the sediments indicates Iocalized deposition nearest
the wastewater outfall during 2018. It should however be noted that the long-
term trend for selenium at station Bl has remained comparatively low since
-20I6 (Appendix 1).
on istent with previous years, spatial trends indicate that the greatest uptake
f st lenium by fish was generally localized to the vicinit of the wastewater
utf, 11 and lower reservoir (Stations B I and B3) during 201 (Appendix H). A
grad ent of significantly greater selenium concentrations was vident near the
waste -water discharge at Station B I when compared to the concentrations at the
upstream sampling location Transect G. Long term selenium concentration
trends in catfish, Bluegill and Largemouth Bass muscle tissues continue to
exhibit decreases at both transects (Appendix J-L).
3.2.6 Additional trace elements (Sb, B, Tl, Mo, and Mn.)
All recorded concentrations for antimony (Sb) were below the laboratory
reporting limit of0.50 µg/L during 2018 except for one observation in June at
Station B 1 (Appendices D, E, and F). These results have been consistent with
previous years, indicating that input of antimony due to station operations is
limited.
Concentrations of boron (B) were detected at all locations throughout the
reservoir during 2018 (Appendices D, E and G). Observations ranged from 118
— 412 µg/L, with a gradient of higher concentrations downstream closer to the
waste -water discharge. These concentrations are well below the minimum
lethal concentration for minnows exposed to boron in the form of boric acid for
6 hours, reported to be 18,000 to 19,000 mg/I (USEPA 1986). Mean annual
concentrations of boron have greatly reduced since 2012 due to increased
rainfall and operation of the thermal evaporator treatment system (Appendix F).
All measured molybdenum concentrations were low (< 7.0 µg/L) and fell well
below the water quality standard of 160 µg/L (Appendices D, E, and G).
Thallium concentrations measured in the surface waters were less than the
reporting limits (0.1 µg/L) on all but two occasions during 2018 (Appendices
D, E, and G). These concentrations from June were just above reporting limits
at 0.19 and 0.1 1 µg/L for stations B I and 132 respectively.
No significant difference was detected for the mean concentrations of
manganese in the surface waters of main reservoir (Stations B2, E2, G2), or
along Transect B during 2018 (Appendices E and G). Periodic elevation of
manganese concentrations associated with the natural, seasonal stratification
and cycling of manganese has been detected in the surface waters of the main
reservoir (DEP 2015).
3.3 Phytoplankton
Primary productivity was assessed through chlorophyll a concentration, a surrogate of
algal biomass. Concentrations measured at Stations B2, E2, and G2 were relatively low
throughout the entire reservoir during 2018, with the exception of one observation at 29
µg/L at G2 during August. All samples remained below the North Carolina State water
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quality standard of 40 µg/L, characteristic of the oligotrophic nature of the reservoir,
(Appendices D, E, and F).
3.4 Biofouling Monitoring
No zebra mussels, reissena polymorpha, or quagga mussels, D. bugensis, ere found
in Mayo Reservoir n 2 18. These mussels are potentially serious biofouling rganisms
in power plant ra% <4 ter systems. Neither species has been collected from Mayo
Reservoir nor are t1l ey expected to become a serious threat to the Mayo Pla t because
reservoir environment 1 conditions are not optimal to sustain a population of these
mussels.
3.5 Aquatic Vegetation
A survey of the aquatic vegetation in Mayo Reservoir was conducted during November
2018. Similar to recent years, Hydrilla, Hycb-illa verticillata, was relatively more
abundant in Mayo Reservoir during 2018 in comparison to the abundance of Brazilian
elodea, Egeria denser. Creeping water primrose, Ludivigia grandiflora, another exotic
species was also present. HydriIla and creeping water primrose dominated the littoral
zone of the reservoir from the headwaters to the dam. No Lyngbya spp. (a filamentous
toxic blue-green algae) was observed in Mayo Reservoir during 2018. The presence of
the observed aquatic vegetation posed no operational issues for the Mayo Station during
2018.
3.6 Fisheries
3.6.1 Species Composition
Twelve fish species were collected during 2018 (Appendix M). No changes in
fish species composition were observed during 2018 compared to previous
years. The Centrarchidae (sunfish) family continued to have the greatest
number of species (seven) collected. Bluegill, Redear Sunfish, and Largemouth
Bass comprised 89% of the total number collected and 80% of the total weight
collected. Other species contributing to the number and biomass collected were
Gizzard Shad, Chain Pickerel, and Green Sunfish. Mayo Reservoir can be
characterized as having a relatively good forage base comprised of Gizzard
Shad. Multiple size classes of Gizzard Shad were present during 2018
indicating consistent spawning success and recruitment of this important forage
species (Appendix O).
During 2018, the abundance of selenium tolerant species such as Green Sunfish
remained low compared to the abundance of Bluegill and Redear Sunfish. Most
Green Sunfish were collected only at locations such as Station B. l that contained
their preferred rocky, rip -rap shoreline habitat (Appendix N).
No disease outbreaks, fish kills, or deformities consistent with selenium
accumulation were observed or reported at Mayo Reservoir during 2018.
3.6.2 Relative Abundance and Size Structure
No adverse spatial trends in relative abundance (mean number per hour) were
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observed for the dominant species collected in Mayo Reservoir (Appendix P)
BIuegill were collected throughout the reservoir during 2018 (Appendix N). No
adverse trend in the annual mean electrofishing catch of Bluegill was evident
from 2005 to 2018 (Appendix P). Annual catches of Bluegill were variable but
no major declines in the relative abundance of Bluegill occurred over the last
fourteen years. Length -frequency distributions indicated that reproduction was
evident throughout the reservoir during 2018 (Appendix Q). There were n
missinj year classe and consistent size distributions were evident over the pa t
five ye rs indicatinr reasonable reproduction and survival (Appe dix R). Th
reservo r-wide mea i relative weight of Bluegill was 81.8 and is cc nsistent with
high fish densities and relatively nutrient -poor conditions that exist in Mayo
Reservoir. This pattern is similar to conditions reported in previous years
indicating no adverse trend in the condition of bluegill (DEP 2013, 2014, 2015,
2016, 2017; PEC 2007, 2008, 2009, 2010, 2011).
Largemouth Bass were collected throughout the reservoir during 2018
(Appendix N). No adverse trend in the annual mean electrofishing catch of
Largemouth Bass was evident from 2005 to 2018 (Appendix P). Similar length -
frequency distributions and the presence of young -of -year and yearling
Largemouth Bass were evident at all locations sampled in Mayo Reservoir
during 20I8 (Appendix T). Good reproductive success and consistent size
distributions for Largemouth Bass have been evident over the past five years
(Appendix U). The mean lake wide relative weight value for Largemouth Bass
was 95.2 during 2018 (Appendix S), and is similar to values reported since 2005
(Appendix V). The proportional size distribution of Largemouth Bass has been
in the range expected for a balanced community since 2005, providing
additional evidence of a healthy Largemouth Bass population (Appendix W).
Redear Sunfish supported a significant recreational fishery in Mayo Reservoir
during 2018 based on length -frequency histograms (Appendix X). No adverse
trend in the abundance of Redear Sunfish was evident from 2005 to 2018
(Appendix P), and although less than optimal, the relative weight values for
Redear Sunfish were similar to previous years and consistent with the
oligotrophic conditions found in Mayo Reservoir (Appendix S).
4. Conclusions
Mayo Reservoir continued to support an aquatic community typical for an oligotrophic
impoundment in the southeastern United States. The relatively small watershed area, low water
inflow, and limited shoreline development within the watershed have influenced the amount of
nutrients entering the reservoir and the subsequent biological productivity. Phytoplankton
densities and productivity, as measured by chlorophyll a, were relatively low and reflected the
nutrient -limited conditions present in the reservoir.
Operational effects of the Mayo Steam Electric Plant on ecological conditions in Mayo
Reservoir continued to be minimal during 2018. Lake wide mean concentrations for trace elements
in surface waters were less than applicable state water quality standards or USEPA national criteria
at all stations, including those sampled in the lower reservoir. Concentrations of these variables
measured in the lower reservoir were greatest at Station Bl near the ash basin discharge. All
selenium concentrations measured in the surface waters of Mayo Reservoir were at or below the
analytical reporting limit during 2018. Concentrations of these analytes have all exhibited declines
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in recent years and are expected to continue to decline in the future.
Selenium continued to have the most elevated trace element concentrations in fish tissues in
Mayo Reservoir. Results indicate that minimal trace element input was restricted to the immediate
vicinity of the wastewater discharge as documented in previous years. Accumulation of arsenic in
fish tissues was not evident at any location sampled in the reservoir during 2018. This trend
indicates that arsenic is not biomagnified up the food chain in a fashion similar to sele ium.
Greater concentrations of seleniul 1 were detected in all Fish tissues collected from the vicin t of
the ash basin discharge when CDMpared to the upper reservoir during 2018. Selen um
concentrations measured in the miscle tissues of catfish, Bluegill and Largemouth Bass ave
decreased from previous elevated avels, and are expected to continue to decline.
Species dominance and distributional patterns within the fish community during 2018 were
similar previous years. The fish community in Mayo Reservoir continues to be a sunfish -
dominated community with Bluegill remaining the dominant species. A robust forage base of shad
was evident as well. While some selenium accumulation was evident in fish tissues, no evidence
of adverse effects to the fish community's species composition or reproduction was observed. The
abundance of selenium tolerant species such as Green Sunfish remained low and most individuals
were collected only at Iocations containing their preferred shoreline rip -rap habitat. Bluegill and
Largemouth Bass were abundant throughout the reservoir and have remained so over the last
fourteen years. Both species also exhibited successful reproduction without indication of missing
year classes. Length distributions, proportional size density indices and robust body conditions
for Largemouth Bass indicated a balanced population with no evidence of sublethal effects due to
selenium accumulation. A Iack of fish deformities associated with selenium accumulation, disease
outbreaks or fish kills during 2018 provides additional evidence of a healthy fish community.
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5. References
APHA. 1995. Standard methods for the examination of water and wastewater. 19th ed. American
Public Health Association, Washington, DC.
Claudi, R., and G. L. Mackie. 1993. Practical manual For zebra mussel monitoring and control.
Lewis Publishers, Boca Raton, FL.
CP&L. 1980. Trace element monitoring 19 79. Carolina Power & Light Company, New h ill, NC.
1997. Largemouth Bass selenium bioassay. Carolina Power & Light Company, N w Hill,
NC.
1998. Mayo Steam Electric Plant 1997 annual environmental monitoring report. Carolina
Power & Light Company, New Hill, NC.
1999. Mayo Steam Electric Plant 1998 annual environmental monitoring report. Carolina
Power & Light Company, New Hill, NC.
�. 2001. Mayo Steam Electric Plant 2000 annual environmental monitoring report. Carolina
Power & Light Company, New Hill, NC.
2002. Mayo Steam Electric Plant 2001 annual environmental monitoring report. CP&L—
a Progress Energy Corporation, New Hill, NC.
DEP. 20I3. Mayo Steam Electric Plant 2012 annual environmental monitoring report. Duke
Energy Progress, Inc., Raleigh, NC.
2014. Mayo Steam Electric Plant 2013 annual environmental monitoring report. Duke
Energy Progress, Inc., Raleigh, NC.
2015. Mayo Steam Electric Plant 2014 annual environmental monitoring report. Duke
Energy Progress, LLC, Raleigh, NC.
2016. Mayo Steam Electric Plant 2015 annual environmental monitoring report. Duke
Energy Progress, LLC, Raleigh, NC.
2017. Mayo Steam Electric Plant 2016 annual environmental monitoring report. Duke
Energy Progress, LLC, Raleigh, NC.
DEP. 2012. Biology Program Quality Assurance Manual, document number NR-00049.
Environmental Services.
Gabelhouse, D. W., Jr. 1984. A length -categorization system to assess fish stocks. N. Amer. J.
Fish. Manag. 4:371-384.
NCAC. 2019. Classifications and Water Quality Standards Applicable to the Surface Waters and
Wetlands of North Carolina. 15A NCAC 02B, SUBCHAPTER 2B - SURFACE WATER
AND WETLAND STANDARDS, Raleigh, NC.
NCDENR. 1976. Metallic Mineral Deposits Of The Carolina Slate Belt, North Carolina. Bulletin
84, Division of Land Resources, Geological Survey Section.
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NCDWR. 2014. Lake and reservoir assessments Roanoke River basin. Division of Water
Quality. Water Sciences Section, Raleigh, NC.
Page, L. M., H. Espinsoa-Pdrez, L T. Findley, C. R. Gilbert, R. N. Lea, N. E. Mandrak, R. L.
Mayden. and J. S. Nelson. 2013. Common and scientific names of fishes from the United
States, Canada, and Mexico. 7 : edition, American Fisheries Society, Special Publication
34, Bethesda, Maryland.
PEC. 2003. Mayo Steam Electric Plan 2002 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh, NC.
_. 2004. Mayo Steam Electric Plant 2003 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh, NC.
2005. Mayo Steam Electric Plant 2004 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh, NC.
2007. Mayo Steam Electric Plant 2006 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh. NC.
_. 2008. Mayo Steam Electric Plant 2007 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh, NC.
2009. Mayo Steam EIectric Plant 2008 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh, NC.
2010. Mayo Steam Electric Plant 2009 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh. NC.
��. 2011. Mayo Steam Electric Plant 2010 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh, NC.
2012. Mayo Steam Electric Plant 2011 annual environmental monitoring report. Progress
Energy Carolinas, Raleigh, NC.
PESC. 2006. Mayo Steam Electric Plant 2005 annual environmental monitoring report. Progress
Energy Service Company, LLC., Raleigh, NC.
USEPA. 1979. Methods for the chemical analysis of water and wastes. U.S. Environmental
Protection Agency, EPA-604-79-020, Cincinnati, OH.
USEPA. 1986. Quality criteria for water 1986. U.S. Environmental Protection Agency,
EPA-440'5-86-001, Washington, DC.
USGS. 2012. U.S. Geological Survey, StreamStats Program Ver. 4.3.0, site visited 4.'2!I9 at
http:%lstreamstats.usgs.gov.
Wege, G. J., and R. O. Anderson. 1978. Relative weight (Wr): a new index of condition for
Largemouth Bass. Pages 79-91 in G. D. Novinger and J. D. Dillard, editors. New
approaches to management of small impoundments. American Fisheries Society, North
Central Division. Special Publication 5, Bethesda Maryland.
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Wetzel, R. G. 1975. Limnology. W. B. Saunders Co. Philadelphia, PA.
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Appendix A. Depth profiles of water temperature (IC) at Mayo Reservoir
during 2018.
0
2
4
6
E 10
0,14
C) 18
20
22
24
26
Station G_2
Water temperature (°C)
nn CA An n AC
6Y.Y 1
1/�����
-*--Feb -*-Apr -*-Jun Aug -$-Oct -0-Dec
0.0 5.0
2
4
6
E 10
12
Q 14
4) 16
0 18
22
24
26
-0-Feb -&-Apr - Jun -"-Aug - Oct tDec
0.0
0
2
4
6
E10
a14
16
18
20
22
24
26
5.0
Station E_2
Water temperature (°C)
10.0 15.0 20.0 25.0
Station B_2
Water temperature (°C)
10.0 15.0 20.0 25.0
.0
30.0 35.0
--4--Feb --*-Apr -*--Jun Aug -0-Oct - Dec
J
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Appendix B.
0.01
0.0
0
2
4
6
E 10
s 12
CD6
18
20
22
24
26
0.0
0
2
4
6
-- 8
E 10
= 12
14
16
018
20
22
24
26
Depth profiles of dissolved oxygen (rng/L) at Mayo Reservoir
during 2018.
Station G_2
Dissolved oxygen (mg/L)
2.0 4.0 6.0 R_n inn 49 n 4A n
2.0
Station E_2
Dissolved oxygen (mg/L)
4.0 6.0 8.0 10.0
12.0 14.0
-4-Feb -411--Apr --*-Jun -%--Aug Oct fDec
Station B 2
Dissolved oxygen (mg/L)
2.0 4.0 6.0 8.0 10.0
12.0 14.0
Feb —6—Apr -Jun -w-Aug-4-Oct Dec
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Appendix C. Depth (m) profiles of the water temperature (°C), dissolved oxygen
(mg/L), pH, and specific conductance (µ&cm) at Mayo Reser%-oir
during 2018.
February 14,2018
April 3. 2018
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix C. (continued)
June 5, 2018
Temperature
E2
G2
BI
Dissolved
82
83
oxygen
E2
G2
Bl
B2
pH
133
E2
GZ
Specific
BI
BZ
conductance
B3
E2
G2
Depth
B1
82
B3
0.2
27.1
27.6
28.7
28.8
29.1
8.3
8.4
8.5
8.6
9.4 1
7.7
7.8
7.9
7.9
8.4
134
131
125
419
108
1.0
26.7
27.4
28.1
28.8
29.1
9.4
8.4
8.6
8.6
9.4
7.8
7.9
7.9
7.8
8.4
128
130
124
119
108
2.0
26.6
26.9
27.2
27.4
27.5
8.3
8.4
8.
8.7
9.0
7.7
7.9
7.9
7.9
7.7
141
129
123
119
17
3.0
26.3
26.6
27.4
26.9
27.0
7.9
7.4
8.
8.3
7.7
7.5
7.6
7.7
7.6
7.2
204
130
124
119
4.0
25.4
24.0
25.4
24.1
25.4
7.8
6.9
fi.
4.3
2.6
7.4
7.0
7.(4
6.7
b.5
137
119
119
105
5.0
20.5
Z 1.6
20.9
21.7
5.5
3.
2.6
0.3
6.8
6.fi
6.5
6.3
115
108
99
6,0
18,3
18.2
17.8
17.6
6.7
6.
4.6
0.2
6.9
6.8
6.7
6.3
128
125
120
I
7.0
I6.0
I6.3
15.9
15.7
6.8
11.
4.6
0.2
6.9
6.9
6.7
6.3
131
130
125
$.0
14.9
14.7
14.6
6.7
4.0
0.3
6.9
6.6
6.4
132
125
9.0
13.9
13.6
14.0
6.0
4.1
0.3
6.8
6.6
6.5
1 132
1 127
129
10.0
12.6
1 12.7
13.8
1 6.2
3.6
0.3
6.8
6.5
6.6
1 134
129
131
11.0
11.9
1 12.4
1 6.3
2.8
6.8
6.5
135
130
12.0
11.3
11.3
1 6.0
3.3
6.7
6.4
135
133
13.0
10.6
10.7
5.9
2.9
6.7
6.2
136
135
14.0
10.4
I0.3
6.0
2.5
6.7
6.2
136
137
15.0
10.1
10.2
6.1
2.6
6.7 1
6.2
136
138
16.0
9.9
10.2
6.2
2.7
6.6 1
6.2
136
139
17.0
9.9
10.1
6.5
1
2.8
6.6 1
6.2
137
139
18.0 1
9.8
1
6.4
6.6 j
137
19.0 1
9.7
5.5
6.5
137
20.0 1
9.6
5.4
6.4
137
21.4 1
9.5
5.3
6.4
138
22.0
9.4
4,8
6.3
139
23.0
9.2
,6
6"
145
24.0
9.2
I.1
6.2
152
25.0
9.1
4.6E�H
6,3
157
Aueust 2. 2018
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Appendix C. (continued)
October 3 2018
Temperature
Dissolved oxygen
pH
Specific conductance
Depth
Bl
I B2
B3
I E2
I G2
-131
B2
I B3
E-2'1
G21
Bl
B2
B3
E2
G2
BL
B2
B3
E2
G2
0.2
24.9
25, I
25.5
25.3
26.6
7.9
8, I
7.9
8.4
9,1
8.0
7.6
7.8
7.3
7.4
1 12
112
111
104
100
1.0
25.0
25.1
25.4
25.3
25.0
7.9
8.1
7.9
8.4
9.0
7.7
7.5
7.6
7.3
7.3
113
112
111
104
100
.0
24.9
25.0
25.2
24.9
24.7
7.4
8.0
7.9
8.2
8.1
7.5
7.4
7.6
7.1
7.0
127
1I1
111
104
100
.0
25.0
25A
24.7
24.5
8.0
7.8
7.4
2
7.4
7.5
7.0
6.8
111
III
104
I00
.0
1.0
24.9
25.0
24.4
24.2
7.9
7.8
5.5
.0
7.3
7.4
6.8
6.6
110
110
106
97
.0
24.8
24.7
24.1
24.1
7.8
7.5
4.0
.6
7.2
7.4
6.7
6.6
110
110
102
-
97
24.7
24.2
24.0
23.6
6.1
3.7
3.9
.5
7,1
6.9
6.7
6.6
114
106
101
94
7.0
23.0
23.6
23.1
23.4
0.7
2.0
0,2
.3
6.6
6.8
6.5
6.7
102
104
78
94
8.0
21.3
21.2
21.8
0.6
0.2
0.3
6.4
6,616.9
113
87
97
9.0
19,1
18.5
18.1
0.3
0.2
0.4
6.4
6.717.0
132
130
186
10.0
15.9
15.0
0.2
0.2
6.4
6.7
139
141
I1.0
13.1
13,3
0.1
0.2
6.4
6.8
137
144
12.0
11.8
12.0
0.3
0.2
6.3
6.8
138
148
13.0
11.1
11.5
0.5
0.2
6.3
6.8
137
149
14.0
10.8
11.0
0.5
0.2
6.3
6.9
139
158
15.0
10.7
10.8
0.5
0.2
6.3
6.9
139
165
16.0
10.5
10.7
0.4
0.3
6.3
6.9
140
171
17.0
10.4
1
10.7
0.5
0.4
f
6.3
6.9
141 1
172
18.0
10.3
0.9
6.4
138
19.0 1
10.2
0.9
6.3
139
20.0 1
10,1
0.8
6.4
I41
21.0
10.0
0.7
6.5
140
22.0
0.3
6.5
151
23.0
49.7
0.3
6.6
160
24.0
1
0.2 1
6.6
160
December 17, 2018
Temperature
Dissolved
oxygen
pH
Specific
conductance
Depth
B1
B2
B3
E2
G2
B1
B2
B3
E2
G2
Bl
I B2
B3
I E2
I G2
Bl
B2
B3
E2
G2
0.2
8A
8.5
8.9
8.4
7.5
8.9
9,2
9.6
9.6
I0.5
7.0
7.2
7.2
7.2
6,9
112
107
107
90
79
1.0
8.4
8.5
8.7
8.3
7.4
9.7
9.1
9.4
9.5
10.5
7.0
7.1
7.1
7.1
6.9
110
107
107
81
78.2
2.0
8.2
8.5
8.7
8.2
7.1
8.7
9.0
9.4
9.5
10.6
7.0
7.1
7.1
7.0
6.8
I09
107
I07
90
75.8
3.0
8.3
8.5
8.7
8.2
6.5
8.8
9.0
9.4
9.4
10.8
6.9
7.0
7.0
7.0
6.7
121
107
107
90
67.4
4.0
9.0
8.4
8.
88.2
6.3
10.7
9.0
9.3
9.4
10.9
7.0
7.0
7.0
7.0
6.6
287
107
107
90
63.1
5.0
8.4
8.7
8.2
6.1
9.0
9.3
9.3
11.0
7.0
7.0
7.0
6.5
107
107
90
57,5
6.0
L4
8.6
8.0
6.2
9.0
9.3
9.2
10.8
7.0
7.0
6.9
6.5
107
107
88
62.4
7.0
8.4
7.8
6.0
9.0
9.2
10.6
7.0
6.9
6.5
107
87
61.8
8.0
8,4
7.8
6.0
9.0
9.1
10.6
7.0
6.9
6.5
107
86
60.6
9,0
8.4
7.6
6,0
9.0
9.21
9.8
7.0
6.9
6.6
I07
84
59
10.0
8.4
7.5
9.0
9.21
7.0
6.9
107
83
11.0
8.4
7.5
9.0
9.2
7.0
6.9
107
82
12.0
8.4
7.4
9.0
9.1
7.0
6.9
107
80
13.0
8.4
7.2
9,0
9.1
7.0
6.8
107
80
14.0
8.3
7.2
8.4
9.1
7.0
6.8
106
80
15.0
8.3
7.2
8.9
9.1
7.0
6,9
106
80
16.0
8.3
7.2
8.9
9.1
7.0
6.81
1051
80
17.0
9.3
7.2
8,9
9.1
6.9
6.81
105
1
80
18.0
8.3
8.9
1
6.9
1
105
19.0
8.2
8.8
1
6.9
1
102
20.0
8.1
8.8
6.9
101
21.0
8.1
8.8
6.9
101
22.0
8.1
8.8
6.9
101
23.0
8.1
8.8
6.9
101
24,0
8.1
8.8
6.9Ll
I
101
Duke Energy Progress, LLC A-5 Water Resources Unit

Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix D. Concentrations of limnological variables measured in the surface
waters of Maya Reservoir during 2018.1
Station
Bl
]Month
TDS
Turbidity
depth Secchi
i'hlornphylla
NILrN
NOS+NO=-N
T
P
Fcb
109
1.7
33
-
0.03
0.44
< 0.12
0.010
Apr
3
4.0
2.4
- _
< 0,01
0.05
< 0.12
0.020
Jun
186
1 45.4
03
- 2
0.07
0.03
0.5
0.052
Aug
7
1.3
3.3
- _
< 0.01
< 0.02
0.2
0.013
Oct
92
2.3
- 4
- 2
< 0.01
< 0,02
0.41
0.013
Dec
77
3.0
1.9
- 2
0.08
0.06
0.55
0.011
Month
C'22*
Cl`
No
S042`
Alkalinity
Hnrdn"s
As
Feb
12
21
4.8
1 5.3
12
22
50
0.6
Apr
12
21
5.2
5.5
16
23
52
0.8
Jun
21
74
6.9
8.1
65
16
82
4.5
Aug
10
16
4.1
5.3
12
22
43
0.7
Oct
7.9
13
3.6
< 5.0
10
22
34
0.7
Dec
8.8
13
3.8
< 5.0
10
22
38
0.7
Month
On
E'J
lag
Mn
14Io
TI
Sh
Se
Feb
1.0
0,08
1.49
26
5.7
< 0.10
< 0.5
< 0.5
Apr
0.88
< 0.08
0.674
36
6.5
< 0.10
< 0.5
< 0.5
Jun
6.1
< 0.08
0.716
121
6.9
0.19
0.81
0.7
Au
1.1
< 0.08
0.634
28
5.4
< 0.10
< 0.5
< 0.5
Oct
1.2
< 0..08
1.86
28
4.3
< 0.10
< 0.5
< 0.5
Dec
1.4
< 0.08
1.23
148
5.1
< 0.10
< 0.5
< 0.5
Station B2
TN:TP I TOC
-3 1 3.7
- 3 4.0
I0 4.3
15 4.8
32 5.1
50 4.5
B
412
379
385
313
220
227
Month
TDS
'Turbidity
Secehl
Je tb
Chlorophyll a
NIb-N
NOi+NOi-N
TIti
'PP
TNXi'
Feb
93
1.3
1.3
2.1
0.04
0,04
0.12
< 0.005
- 3
Apr
84
2.7
2.7
4.2
< 0.01
0.05
0.23
0.009
18
Jun
86
- J
2.9
5.4
0.02
•: 0.02
0.26
0.007
- 3
Aug
91
1.3
1.3
3.6
< 0.01
10.02
0.25
0.014
- 3
Oct
80
1.9
1.9
3.6
< 0.01
10.02
0.32
0.015
- 3
Dec
84
4.0
4,0
2.1
0,08
0.06
0.50
0.010
17
]Month
Cart
C€'
IM941)
Nn
5042-
Alkalinity
Hardness
As
B
Feb
12
19
1 4.7
5.1
11
22
50
0.6
403
Apr
1€
19
4.9
< 5.0
11
22
46
0.6
346
Jun
11
17
4.2
< 5.0
13
20
44
0.7
285
Aug
10
16
4.2
5.1
12
21
43
0.7
305
Oct
7.9
13
3.6
< 5.0
10
21
35
0.7
212
Dec
8,1
13
3.6
< 5.0
8.6
21
35
0.6
773
Month
Gu
Cd
IIg
IITn
€ifo
Ti
Sb
Se
Feb
< 1.0
< 0.08
0.504
23
5.7
r 0.10
< 0,5
< 0,5
Apr
0.7
< 0.08
< 0.50
19
5.1
0.10
< 0_5
< 0.5
Jun
1.2
0.091
0.863
20
4.7
0.11
< 0,5
< 0,5
Aug
1.4
< 0.08
0.709
26
5.3
0.10
< 0.5
< 0,5
Oct
1.1
< 0.08
3.63
30
4.5
0.10
-0.5 0.5
< 0,5
Dec I
L I
< 0.08
1.28
131
4.8
0.10
.. 0,5
< 0,5
TOC
3.7
3.9
4.4
4,8
5.5
45
Duke Energy Progress, LLC A-6 Water Resources Unit

Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix D (continued)
Station B3
Month
TDS
Turbidity
Sephi
depth
Chlorophyll
NFIj,N
NOS+NOt-N
TAT
TP
TN:TP
TOV
Feb
95
1.1
3.6
-=
004
004
<0.12
0.006
-]
3.7
Apr
87
5.1
3.6
- =
0.01
0.06
0.18
< 0.005
- 3
3.9
Jun
1 84
2.3
2.6
-2
0.02
0.02
0.40
0.008
?
4.3
Aug
85
I.8
2.9
- 2
0.01
0.02
0.16
0.014
9
45
Oct
80
2.3
- S
-2
0.01
0.02
0.28
0.013
5
5 5
Dec
78
3.2
2.1
- 2
0.07
006
0.47
0.011
2
44
Mouth
Gaza,
GI'
met)
Na
8042"
Alkalinity
hardness
As
B
Feb
12
< 0.5
4.6
5.2
11
22
48
0.5
410
Apr
If
< 0.5
4.8
< 5.0
11
22
46
0.6
330
Jun
10
{_ 0.5
4.2
< 5.0
11
21
43
0.6
275
Aug
9.7
< 0.5
40
5.2
11
21
40
0.7
3U5
Oct
7.8
0.5
3.6
5.0
9.8
22
34
0.7
208
Dec
8.2
< 0.5
3.6
5.0
8.6
21
35
06
223
Month
Cu
Cd
Hg
Mn
Mo
TI
Sb
Se
Feb
< 1.0
< 0.08
0.6
26
5.5
< 0.1
0.5
< 0.5
Apr
0.8
< 0.08
0.50
19
52
< 0.1
0.5
< 0.5
Jan
1.2
< 0.08
0.951
77
4.5
< 0.1
t. 0.5
< 0.5
Aug
1,0
< 0.08
0.591
37
5.2
< 0.1
< 0.5
•. 0.5
Oct
1.1
< 0.08
2.17
22
4A
{ 0.1
< 0.5
< 0.5
Dec
2.0 1
c 0.08
1.33
118
4.8
c 0.1
: 05
< 0.5
Station E2
Month
TDS
Turbidity
Seechi
depth
Chlorophyll a
NrFba N
NOi + NOi N
TN
'RY
TN:TP
TOC
Feb
95
2.1
2 5
2.7
0,03
004
< 0,12
0.006
- 3
3.8
Apr
83
4.8
2.7
3.6
< 0.01
005
0.20
0.011
6
3.8
Jun
86
2.3
2.0
60
0.02
0.02
0.24
0.009
4
45
Aug
79
2.1
2.4
3.9
< 0.01
0.02
0.29
0.013
4
4.6
Oct
86
2.2
22
8.4
< 0.01
0.02
0.43
0.015
3
6.0
Dec
70
3.3
2.4
5:I
0.09
0.0-
0.46
0.0I4
3
5.0
Month
Cnu')
Cr
Niel)
No
SO42
Alkalinity
Hardness
As
B
Feb
11
19
4.4
< 5.0
11
20
46
0.5
373
Apr
10
18
4.6
c 5,0
11
22
45
0.5
317
Jun
9.5
16
4,0
a 5.0
10
22
40
0.6
260
Aug
9.7
15
4.0
< 5.0
I0
21
41
07
277
Oct
73
12
3.2
< 5.0
8.6
21
31
0.6
181
Dec
7.0
10
3.1
c 5.0
66
18
30
0.5
162
Month
Cu
Cad
Hg
bin
bbo
T1
Sh
Se
Feb
1 0
< 0.08
0.509
20
4.8
0.1
0.5
< U.5
Apr
I_I
<OAB
0.597
19
4,7
<0,1
<0.5
<0.5
Jun
I.3
< 0.08
0.846
24
4,2
< 0.1
< 0.5
< 0.5
Aug
2.5
< 0.08
0.541
22
5.1 1
< 0,1
< 0.5
< 0.5
Oct
1.7
< 0.08
3.08
21
39
< 0.1
< 0.5
< 0.5
Dec
1.6 1
c 0. 08
1.75
86
3.3
< 0.1
0.5
< 0. 5
Duke Energy Progress, LLC A-7 Water Resources Unit

Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix D. (continued)
Station G2
14laoth
TDS
Turbidity
5rcth . Chlorophylla' Nib-N
depth
NOs+NOi-N
TN
`CP
TN:TP
TOC
Feb
86
10
0.9 6.6 < 0.01
0.06
< 0.. 2
0.018
- 3
4.2
A r
68
6.8
1.4 5.7 < 0.01
.08
0. 2
0,033
15
4.6
Ju
73
4.2
1.4 8.4 0.03
< (.02
0. 1
0.014
7
5.1
Ack
85
2.9
E6 29.0 < 0.01
< (.02
0. 1
0.021
7
4.7
t
76
2.4
1.2
16.5
< 0.01
< .02
0. 8
0.019
5
6.3
Dec
58
5.2
1.2
11.1
0.04
0.09
0.30
0.022
7
4.8
Ntonth
Gn20]
CI_
mel)
No
.8043,
Alkalinity
Hardness
As
B
Feb
8.9
14
3.6
5.0
8.6
18
37
<0.5
242
Apr
7.6
13
3.7
< 5.0
7.8
20
34
0.4
184
Jun
8.6
13
3.6
< 5.0
8.4
20
36
0.5
215
Aug
8.6
14
3.6
< 5.0
8.7
21
36
0.7
252
-Oct
7.2
11
3.3
< 5.0
7.8
21
32
0.7
172
Dec
5.9
8
2.8
< 5.0
5.5
17
26
0.5
118
14lonih
Cu
Ca'
HR
bin
MD
T]
Sh
5e
Feb
1.6
< 0.08
1.64
38
2.4
< 0.1
< 0.5
< 0.5
Apr
2.2
< 0.08
1.75
25
2.5
< 0A
< 0.5
< 0.5
Jun
1.9
< 0.09
1.14
27
3.3
< 0.1
< 0.5
< 0.5
Aug
i.2
< 0.08
0,643
27
4.2
< 0.1
< 0.5
< 0.5
Oct
3.3
<0.08
2.3!
26
3.6
<0.1
<0.5
<0.5
Dec
2.2
< 0.08 1
2.2
46
2.1 1
< 0.1
<
IUnits are as lollows- n� I_ (TDS, NI h-N, NO,-- N0= N_ TN, 'ri,. TOC, Ca'`, Cl`, N.Ig=-, No'. SOa total alkalinity jas CaCOa I,
hardness icalculated as mg cqui,6alents CaCOj:[.i), ui 1. (chloroph%ll a. As. B, Cu, Cd. ,tiin,. Ala. TI. Sb. Sc), R' l(I3g).
:1Tt � (Turhidiq), meter (Secchi depth)_ Less than Nalucs indicate the loner reporting limit Ibr that parameter.
`Secchi disk data and chloropkyli a samples %sere collected on[% at Stations B2. F2. and G2.
4TN:Tl' values not be calculated due to TN concentrations below reporting limits.
Data unavailable.
Duke Energy Progress, LLC A-8 Water Resources Unit

Mayo Steam Electric Plant
2018 Environmental Monitoring Report
Appendix E. Spatial
trends
of means and ranges for selected limnological
variables
from surface waters of Mayo Reservoir
at Stations B2, E2, and G2
during
2018.1
Variable
Total dissolved solids (mg/L)
86.0
80-93
83
70-55
74
58-86
Turbidity (NTU
2.2 h
I.3-4.0
2.8 b
2.1-4.8
5.3
2.4-10
Secchi disk trap parency (m)
2.41
1.3-4.0
2.4.
2.0-2.7
1.3"
0.9-1.6
Chloro h Ila( L)
3.51'
2.1-5.4
5.0
2.7-8.4
12.92
5.7-29
Nutrients (mg/ )
Ammonia-N
0.02
<0.01-0.08
0.03
<0.01-0.08
0.01
:0.01-0.04
Nitrate + Nitrite N
0.03
<0.02-0.06
0.03
<0.02-0.07
0.04
<0.02-0.09
Total nitrogen
0.27
<0.12-0.50
0.28
<0.12-0.46
0.25
.0.12-0.38
Total phosphors
O.0 i 0 b
<0.005-0.0 I5
0,01111
0,006-0.015
0.021 s
= 0.014-0.033
Total organic carbon (mg/L)
4.6
3.7-5.5
4.6
1 3.8-6.0
4.6
4 2-6.3
Ions (mg/L)
Calcium
9.9.
8-12
9.1
7.0-1I
7.71
5.9-8.7
Chloride
16 „
13-19
15
9.8-19
12
8-14
Magnesium
4.2'.
3.64.9
3 9 '-
3.I4.6
3.4
2.8-3.7
Sodium
5.0
<:5.0-5.1
5.0
- 4
< 5.0
-..5.0-5.0
Sulfate
11
8.6-I3
9.5
6.6-11
7.81
5.5-8.7
Total alkalinity Z
21
20-22
21
18-22
20
17-21
Hardness 2
423
35-50
39
30-46
33
26-37
S eci fic conductance S/cm
126
107-143
116
90-132
106 b
79-134
Trace elements (pg/L)3
Antimony [5.6]
0.5
-4
0.5
- 4
0.5
-4
Arsenic [101
0.64
0.55-0.74
0.53
0.45-0.73
0.50
0.41-0.69
Boron [6001
29611
212403
262 A':
I62-373
197 b
1 18-252
Cadmium [ 1.21
0.08
< 0.08-0.09
� 0.08
- 4
0.08
- 4
Copper [5.41
1.0 Q
c 1.0-1.4
1.54
< 1.0-2.5
2.1 b
1.2-3.3
Manganese[2001
41
19-131
32
19-86
31
25-46
Mercury (ng/L) [ 12.0] 5
1.2
< 0.5-3.6
1.2
0.51-3.1
1.6
0.64-2.3
Molybdenum [160]
5.0 °
4.5-5.7
4.3'
3.3-5.1
3.0 b
2.14.2
Selenium [5]
� 0.5
- 4
< 0,5
_ 4
0.5
- 4
Thallium [0.241
< 0.1
< 0.1-0.1 1
< 0.1
- 4
. 0.1
_ 4
Fisher's protected least significant difference test ums applied only if the overall F test for the treatment was significant. Shaded
station means followed by different superscripts for a given variable were significantly different (P 5 0.05). Less than values
indicate the lower reporting limit for that parameter for that sampling year. Statistical analyses do not include values less than
the reporting limit. Sample size equaled 6 for all variables unless otherwise noted. Rounding may obscure mean separations.
Total alkalinity measured as mg/L as CaCOj; hardness calculated as mg equivalents CaCO3/L.
3North Carolina %water quality standard, (average hardness used for calculation of acute standard for copper and cadmium), or
USEPA recommended water quality criteria are in brackets for reference-
5 All measured values were below% the laboratory reporting limit.
EPA low-level method 1631E used for analysis at all locations (lower reporting. limit = 0.50 ng/L).
Duke Energy Progress, LLC A-9 Water Resources Unit

Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix F. Long-term trends of means for selected limnological variables from
surface waters of Mayo Reservoir at Stations B2, E2, and G2, 2005
2018.
Secchi disk transparency depth
40
_ 35 -
30
L
25
e
y 20 P
15 i
101
05
00
'Lao Too 7p01 1 y0d910�010�1 Z0�110�3101� 10151pi61011 1p�!
Year
--a- B2 -*.-E2-G2
Total Nitrogen
070
060
$ 050
C
040
i
c 030
0
U 020
a 10
0 00 L— -
M1�"- 10� 10� 10� T" 10�0101� 10421015 ,101� 10\5 ,10�610�'i ,10�6
Year
Chlorophyll a
too
z
4 80
80
c
U 40
20
00 LL5
T" 1006 1p001009101C 10�� 1011 010�� 1015 ,10161011 10�6
Year
-Q-- 82 ---&- E2 t G2
Turbidity
9a,
so=
70
c
c so ,
50
c
4a
U30
201
1a �
00.01001 100°� 10100 TOO 0, 1006
Year
--G-B2 - 6-E2 --O-G2
Total Phosphorus
0 046 r -
0 041 ,
0 036
E 0.031
5 0 026 j
0 021
c Oats
U
0 011
a 006
10p51dd61001 100� 1`�' 10�010�� 10i1.�p13101� ,101510161011 10�4
Year
--41--92 --*-E2 +G2
Boron
r500 j — - .
Ronan not.j
�j 1200
C4
4 sa0 ,
c
U 1
i
3iaa
1�' � 1� �'L"- :0�010�' 101'i 1013104a ,Z015 ,�p16101Z ,10�6
Year
B2 err E2 02
Duke Energy progress, LLC A-10 Water Resources Unit

Mayo Steam Electric plant 2018 Environmental Monitoring Report
Appendix F. (Continued)
Chloride
eoo -
70 0 �
E 600
1
Q Sao
400
c 300 +
U
200
!
100 '
on
M1� � 1� 9,dOb �-°� 1q�0 1°1� gp11,�013 ,lg1b gb'1b y°fib M1q;1 1°;b
Year
—a— 82 —*— E2 � G2
Hardness
IQ —
120
rn
E 100
4 B0
c '
00
o
is 40
20
YON
--a— E2 02
Total arsenic
5o.-
s7 40
rn
1
s 30 -
L."rRepaning Unh
La
2004.2009 a 1A Ook
2010-201! a 0.1 .11.
2010-2010 4 0 1 WL
0 20
U �
10=
23
_
Zo, 00 of 1ao oft
101° ZO �0�1.0'1b
Ito ,Call" 1001110.E 1011
Year
--.&—E2
t02
Total dissolved sobds
200 --
175
E 150 -
!25
m
100
c 75 j
U
50
25
0 �
Year
—&--B2 —*---E2 —.W-02
SOE- icconducta^cc
360 ,
320
280
240
200
160 '
120
ao
40
0
qo°`' 1oPb 1� 1°°b 'to'0b Zq;e 1°;+ 1°�z. ,�°;b 1°;► ,�°;310;b 1°;'i �°aa
Year
—o— 82 A E2 --G--- G2
Total selenium
5o
40 4
S
30
c
c 20
U
101
03
,,�1,—
Year
�a B2 --gi--E2 tG2
La"r Mpogh,0 LkM
2004.2001 s 10 PgIL
2010.201a a 0.5 VOX
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix G.
Spatial trends of means and ranges for selected limnological variables
from surface waters of Mayo Reservoir along Transect B during 2018.1
S ion 131
Total dissolved solids (mg/L)r9.
77-186
St
86
80-93
Turbidi TU
1.3-45
2 2
1.3-4.0
Nutrients (mg/L)
70,26<
Ammonia-N
.01-0.08
0.02
':0.01-0.087
Nitrate + Nitrite N
0,03
.02-0.06
0.03
<.0.02-0.0606
Total nitrogen
0.30
0.12-0.55
0.27
� 0.12-0.5047
Total phosphorus
0.019
0.008-0.052
0.010
<0.005-0.015
0.009
-.0.005-0.014
Total organic carbon (mg/L) 4.4
3.7-5.1
4.6
3.7-5.5
4.4
3.7-5.5
Ions (mg/L)
Calcium
12
7.9-21
9.9
8-12
9.7
7.8-12
Chloride
18
13-24
16
13-19
16
13-19
Magnesium
4.7
3.9-6.9
4.2
3.64.9
4.1
3.64.8
Sodium
5.0
<5.0-8.1
< 5.0
<5.0-5.1
5.0
5.0-5.2
Sulfate
21
10-65
11
8.6-13
11
8.6-11
Total alkalinity'-
21
16-23
21
20-22
21
21-22
Hardness Z
50
34-82
42
35-50
41
34-48
Specific conductance (µS/cm) 131
1 12-153
126
107-143
I24
107-I36
race elements (µg/L)3
Antimony [5.6]
0,5
< 0.5-0.8
0.5
-4
< 0.5
- 4
Arsenic [10]
1.3
0.64.5
0.6
0.6-0.7
0.6
0.5-0.7
Boron [600]
323
220-412
296
212-403
291
208-410
Cadmium [ 1.31
< 0.08
- 4
< 0.08
Y 0.08-0.09
0,08
-4
Copper [6.21
1.9
< 1.0-6.1
1.0
1.0-1.4
1.1
< 1.0-2.0
Manganesef2001
64
26-148
41
19-131
41
19-118
Mercury (ng/L) [12.01
1.1
0.6-1.9
1.2
< 0.5-3.6
l.0
:0.5-2.2
Molybdenum [1601
5.7
43-6.9
5.0
4.5-5.7
4.9
4.4-5.5
Selenium [51
< 0.5
<0.5-0.7
< 0.5
-'
. 0.5
- 4
Thallium rO.241
<0.1 1
<0.1-0.2 1
<0.I
0.1-O.11
t 0.1
-4
1Fisher's protected least significant difference test was applied to the surface samples only if the overall F test for the treatment
was significant. Shaded station means followed by different superscripts for a given variable were significantly
different (P a 0.05), Less than values indicate the lower reporting limit for that parameter for that sampling )car. Statistical
analyses do not include �alucs less than the reporting limit. Sample size equaled 6 for all variables. Rounding may obscure
mean separations.
'Total alkalinity measured as mgiL a% CaCO}; hardness calculated as mg equi%alents CaCO]/L.
3North Carolina water quality standard (a%crage hardness used for calculation of acute standard for copper and cadmium) or
USEPA recommended water quality criteria are in brackets for reference
5All measured values were below the laboratory reporting limit.
aEPA low-level method 1631 E used for analysis at all locations (lower reporting limit 0 50 ng/L).
Duke Energy Progress, LLC A-12 Water Resources Unit

Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix H. Means and ranges of trace element concentrations (µg/g dry weight) in
the sediments and (eft axial muscle tissues of fish from Mayo Reservoir
during 2018.1
Trans/
Element)
Species
Station
n
Arsenic
Cadmium
Conner
Mercury
Selenium
Sediment
B 1
3
21 a (20.0-21,0)
I .I a( 1-10-1.20)
41 ° (40-42)
0.07 a (0,06-0.08)
19 a (18 - 20)
B3
3
12'(12.0)
0.1 b (0.1 - 0. 1)
38 b (38-39)
0.04 b (0.04-0.05)
4.2 c (4.0-4.3)
G
3
6.5°(6.4-6.7)
0.11(0.1)-0. 1)
114c(113-114)
0.08a(0.07-0,08)
6.01(5.7-6.3)
Bluegill
B I
6
0.4b (0.3-0.6)
< 0.5
3.2 (<4.5-7,0)
0.3 (0.20-0.40)
5.3' (4.2-6.2)
(164-235 mm)
B3
6
0.54 (< 0.5-0.6)
< 0.5
7.8 (1.8-24)
0.3 (0.20-0.50)
5.7" (4.2-6.6)
G
6
0.3'(< 0.5-0,4
< 0.5
2.3 (1.9 - < 4.5)
0.3 (0.20-0.50)
2.712.1-3.6
Catfish=
B 1
6
0.62 (0.4-0.7)
< 0.5
2.1 (1.5 - < 4.5)
0.23 (0.10-0.40)
7A2(6.6-9.4)
(242-341 mm)
B3
6
0,3a (0.2-0.3)
<0.5
1.9 (1.4 - 2.4)
0.3a (0.10-0.30)
3.9b(3.0-4.8)
G
6
< 0,5b
< 0.5
1.8 (1.5 - < 4.5)
0.4' 0,30-0.60
1.91:I.4-2.3
Largemouth
131
6
0.33(0.2-0.3)
<0.5
4.1 (< 4.5-12.9)
12(0.60-2.20)
6.44(4.3-8.0)
301-410mm)
B3
6
0.3ab(0.2-0.3)
<0•5
2.4 (2.3- < 4.5)
0.9(0.60-1.20)
5.6°b(4.3-7.3)
G
6
0.2b 0.2- < 0.5
< 0.5 1
2.2 (1.4- <4.5) 1
1.1 (0.90-3.50) 1
3.3b 3.0-3.5
(Standard errors and statistical results are not shown when the mean was less than the reporting limit. Fisher's protected least
significant difference test was applied only if the overall F test was significant. Shaded station means followed by different
superscripts mere significantly different (P :5 0.05). Rounding may obscure significant differences. The mean dry- to wet -
weight ratios for conversion to wet -weight basis are sediment-0.47. Bluegill-0.19, Largemouth Bass-0.20, and catfish-0.19.
="Catfish" included White Catfish, :imehinrs carts, Yellow Bullhead.:). rratalrs, and Flat Bullhead.:I planceplralrts
Duke Energy Progress, LLC A-13 Water Resources Unit

Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix I. Annual mean trace element concentrations (µg/g dry weight) measured
in sediments collected from Station B1 in Mayo Reservoir, 2005-2018.
250
3 + +
r
200 ++ ! ++ !+
i 150 ++ ► t ! ++
+� ! ti �! `�� • ! ++
` 100
Q 50 +
C
0 .. .. ...
200% ti°°9 MONO tioNik Zo'�y tioNS tiOh Zo'�5 Zo'tb �,0'�1
As Cd - - -Cu ........ Sa
Appendix J. Annual mean selenium concentrations (µg/g dry weight) measured in
the left axial muscle tissue of catfish collected from Transects B and G
in Mayo Reservoir, 2005-2018.
3
a
m
CD
z
C
0
L
C
C
0
U
0
N
25 .
20
15
10"
-"-------------------- - �'�..- - - - - - -
'Ltrill 05110,�001 Zo°o,�0°9,�°�° Zo�o�`��o�� Zo���`' �Ob Ol �o�o
Transect B------- Transect G
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix K. Annual mean selenium concentrations (µg/g dry weight) measured in
the left axial muscle tissue of Bluegill collected from Transects B and G
in Mayo Reservoir, 2005-2018.
W
3
.o
2
L 1
0
w
10
d
=
o 5
U
m
cn
0 F f + -- i - -. - + + —�
To°`' ,006z011 zo'\° ti0.0tirJO z0'0 - ON6 0N6 col �o�a
fr a n-- s'- e- C-' f B
Appendix L. Annual mean selenium concentrations (µglg dry weight) measured in
the left axial muscle tissue of Largemouth Bass collected from
Transects B and G in Mayo Reservoir, 2005-2018.
25 - - —
07
0 -
2°°5 �,0°6 �,o°� do°° Z°°9 �o'�° yo'�'� Zo'�� tio'�� �o'��►,�o'�`' Zo'�6 Zo�'� ,�o'�a
Transect B------- Tr'
nsect G
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix M. Total number and total weight (kg) of fish collected from Mayo
Reservoir
with electrofishing sampling during 2018.
Scientific name'
Common name
Total
number
Total
weight
Clupeidae
herrings
Dorosoma cepediantun
Gizzard Shad
71
14.6
Esocidae
pikes
Esor niger
Chain Pickerel
15
3.9
Cyprinidne
minnows
,1'otentigonus
ct:i-s
Veticas
Golden Shiner
1
,- 0 1
letaluridne2
bullhead catfishes
A. nebtslosus
Brown Bullhead
3
1.6
A. plarycephahrs
Flat Bullhead
8
1.1
Centrarchidae
sunfishes
L. cyanelhis
Green Sunfish
32
0.3
L gulostts
Warmouth
8
0.3
L macrochims
Bluegill
393
8.1
1. nricrolophus
Redear Sunfish
221
21.0
Lepomis hybrid
hybrid sunfish
5
.0.2
A ficroplerus sahnoides
Largemouth Bass
96
50.7
Pomaris nigromaculaurs
Black Crappie
13
3.9
Total organisms 866 106
Totalspecies 12
'Taxonomic nomenclature follo%%s Page et al. (2013).
2Additional species collected For trace element anal)sis include White Catfish. Anreirrrzis caws.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix N.
Mean number per hour for fish collected with electrolFishing sampling
by transect from Mayo Reservoir during 2018.
Taron
Transect B
Transect E
Transect G
Reservoir mean
Gizzard Shad
0.3
1.1
r 4
10.3
Chain Pick rel
0
5.7
2,5
2.2
Golden Shi ter
0
0.6
0.2
Brown Bullhead
0
0.6
I.
0.4
Flat Bullhead
2.2
0
0.5
1.2
Green Sunfish
10
0
0
4.7
Warmouth
1.3
0.6
1.5
L2
Hybrid sunfish
1.3
0.6
0
0.7
Bluegill
55
50
67
57
Redear Sunfish
16
46
45
32
Largemouth Bass
6.4
15
25
14
Black Crappie
0
2.8
4.0
1.9
Total'
92
124
180
126
'Totals may can from column sums duc to rounding.
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix O. Length -frequency distribution of Gizzard Shad collected with eiectrofishing
sampling from Mayo Reservoir during 2018.
20
15
C
4)
i 10
a
5
0
130 150
. , --
17❑ 193 2 1 G
230 250 270 290 310 330 350
Length (mm)
Appendix P. Long-term annual mean clectrofishing catch [Loge (annual mean number per
hour)] for Bluegill, Largemouth Bass, Redear Sunfish and Gizzard Shad collected
from Mayo Reservoir, 2005-2018.
5.0 - - --
o 4.0
Q
L.
3.0 ; r
Mi• . '.
E ,
o
J
0.0 -. i- -f'1-+f 1
Z��S?.��62�0�'ZO��ZO�9Z���ZO��yO'�Z20'�3ZO��yO'�5Zp16Zp'1� Zp'1$
Year
Largemouth Bass — —Bluegill — • —Redear Sunfish ......• Gizzard shad
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix Q. Length -frequency distributions of Bluegill by transect collected with
electrotlshing sampling from Mayo Reservoir during 2018.
25
20
c 15
m
a 10
5
0
25
20
c 15
0
010
5
0
u
d7 50 75 100 125 150 175 2p 225 M
Length (mm)
[5 50 75 100 125 150 175 200 225 250
Length (mm)
e5 50 75 100 125 150 175 200 225 250
Length (mm)
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix R. Length -frequency distributions of Bluegill by year collected using
eiectrofishing sampling from Mayo Reservoir, 2014-2018.
0
15
10
5
0
u
Zo ou /5 100 125 150 175 200 225 250
Length (mm)
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix S. Relative weight values of Bluegill, Largemouth Bass, and Redear
Sunfish collected with electroiishing sampling from Mayo Reservoir
during 2018.
120
CI
3: 100
3 80ID
' ' • " ,
60
W
40 1
Bluegill Mean value = 81.8 t 11.0 (sd). n =194
75 95 115 135 155 175 195 215 235 255
Length (mrn)
120
:: 100
s
•
80
• •
't •. " ..
,
ID
Q:
40 Largemouth Bass Mean value = 95.2 t 9.5 (sd). n = 70
145 195 245 295 345 395 445 495 545 595
Length (mm)
120
L•
100
3so,• • •,. ,;...
m . • + ; r
60.
D:
Redear Sunfish Mean value = 78.5 t 7.5 (sd). n = 220
40
75 95 115 135 155 175 195 215 235 255 275 295
Length (mm)
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix T. Length -frequency distributions of Largemouth Bass by
transect collected with electrolishing sampling from Mayo Reservoir
during 2018.
15
10
Q
15
10
=,A
15
10
n
Transect G
n=49
Jv itni i:)u zw 250 300 350 400 450 500 550 600
Length (mm)
Transect E
n=27
N aw 1Du 200 250 300 350 400 450 500 550 600
Length (mm)
Transect B n=20 I
avu IJU [uu [50 300 350 400 450 506
Length (mm)
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix U. Length -frequency distributions of Largemouth Bass by year collected
with electrofishing sampling from Mayo Reservoir, 2014-2018.
1;
1C
5
0
15
10
5
0
15
a+
aCi 10
ar
a 5
0
15
10
5
0
15
10
5
0
0 50 100 150 200 250 300 350 400 450 500 550 600
Length (mm)
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix V. Mean annual relative weight values for Largemouth Bass by
year collected with electrofishing sampling from Mayo Reservoir,
2005-2018.
105
1 100
95
4 v 90
c 85
m
7- i
80 —' 1
i
75 1 — E --- -r 4 +-- a + +------- —1
24�5 2006 Took Z00� Z�Og ZOZOZO�Z ZOSOO Zp'15 ,L�16 Zp1� �p�i3
Lakewide B — -E - ,G
Appendix W. Proportional size distribution (PSD) of Largemouth Bass by year
collected with electrofishing sampling from Mayo Reservoir, 2005-
2018.
100 T--
90
$o70
i
so
50
N 40
6 30
20
70
0
Z0�5y006Z0�'{ Z40�ZO�920A�ZO��ZO'�ZZO'13,Zp'1�Zp'15Zp'16Zp'1� Zp�;�
—*--Quality (300-379mm) Preferred (380-509mm) --A- Memorable (510-629mm)
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Mayo Steam Electric Plant 2018 Environmental Monitoring Report
Appendix X. Length -frequency distribution of Redear Sunfish collected with
electrofishing sampling from Mayo Reservoir during 2018.
10
8
`+ 6
c
m
a 4
2
a
0
Redear Sunfish
i� h 16�Ihlml
n=221
25 50 75 100 125 150 175 200 225 250 275 300 325
Length (mm)
Duke Energy Progress, LLC A-25 Water Resources Unit