20070812 Ver 1_20 -Yadkin Water Quality-Final_20080502

Yadkin Project
FERC No. 2197
YADKIN WATER QUALITY
FINAL STUDYREPORT
AUGUST 2005
YADKIN PROJECT
FERC No. 2197
YADKIN WATER QUALITY MONITORING REPORT
FINAL STUDYREPORT
Prepared for
ALCOA POWER GENERATING INC.
Yadkin Division
293 NC 740 Highway
Badin, NC 28009-0576
Prepared by
NORMANDEAU ASSOCIATES, INC.
25 Nashua Road
Bedford, NH 03110
R-19700.000
August 2005
Water Quality
Table of Contents
Page
SUMMARY .......................................................................................................................................... X
1.0 INTRODUCTION ....................................................................................................................1
2.0 CURRENT STATUS OF WATER QUALITY IN THE RESERVOIRS AND
TAILRACES (1999-2003) .......................................................................................................9
2.1 METHODS .........................................................................................................................9
2.2 GENERAL TRENDS AMONG RESERVOIRS AND STATIONS .............................................. 15
2.3 WATER QUALITY OF THE RESERVOIRS .......................................................................... 21
2.3.1 High Rock Reservoir .......................................................................................... 21
2.3.2 Tuckertown ........................................................................................................ 28
2.3.3 Narrows .............................................................................................................. 31
2.3.4 Falls .................................................................................................................... 38
2.3.5 Toxic Substances, Chemical Oxygen Demand and Nitrite ............................... 38
2.3.6 Seasonal and Annual Variability ....................................................................... 41
2.3.7 Water Quality of Bottom Waters ....................................................................... 47
2.4 WATER QUALITY OF THE TAILRACES ............................................................................ 54
2.4.1 Monthly Water Quality Monitoring ................................................................... 54
2.4.2 Continuous Dissolved Oxygen and Temperature Monitoring in Tailraces ........ 56
2.5 STATE STANDARDS AND HISTORICAL DATA ................................................................. 71
3.0 IN-DEPTH ANALYSIS OF SPECIFIC WATER QUALITY ISSUES ............................80
3.1 INFLUENCE OF FLOW ON WATER QUALITY ....................................................................80
3.2 INFLUENCE OF RESERVOIR WATER LEVELS ON WATER QUALITY .............................. ..83
3.3 INFLUENCE OF OPERATIONS ON DISSOLVED OXYGEN IN TAILWATERS ...................... ..85
3.3.1 August 2001 Operations Testing ..................................................................... ..85
3.3.2 August 2004 Operations Testing ..................................................................... ..91
3.3.3 Conclusions of Operation Testing ................................................................... 101
3.4 LATERAL AND LONGITUDINAL INVESTIGATION OF DISSOLVED OXYGEN IN THE
VICINITY OF THE DAMS ................................................................................................ 104
3.4.1 Results of Lateral and Longitudinal Survey .................................................... 110
3.5 SUSPENDED SOLIDS TRANSPORT THROUGH THE YADKIN APGI SYSTEM ................... 116
3.6 BIOLOGICAL ISSUES ..................................................................................................... 118
3.6.1 Mercury in Fish Tissue .................................................................................... 118
3.6.2 Fecal Coliform Monitoring .............................................................................. 123
4.0 REFERENCES .....................................................................................................................127
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Water Quality
List of Figures
Page
Figure 1.0-1. Inflow to High Rock Reservoir, 1999-2004 ....................................................................... 3
Figure 1.0-2. High Rock water level 1999 - 2004 (y axis scale of 182 to 192 meters is
equivalent to 597 to 630 feet) ............................................................................................ .. 4
Figure 1.0-3. Tuckertown water level, 1999 - 2004 (y axis scale of 170 to 180 meters is
equivalent to 558 to 591 feet) ............................................................................................ .. 5
Figure 1.0-4. Narrows water level, 1999 - 2004 (y axis scale of 150 to 160 meters is
equivalent to 492 to 525 feet) ............................................................................................ .. 6
Figure 1.0-5. Falls water level, 1999 - 2004 (y axis scale of 95 to 105 meters is equivalent to
312 to 344 feet) .................................................................................................................. .. 7
Figure 2.1-1. Upper Impoundments and Sampling Stations .................................................................. 10
Figure 2.1-2. Lower Impoundments and Sampling Stations .................................................................. I l
Figure 2.1-3. Lick Creek and Tuckertown Reservoirs. Supplemental water quality stations ............... 13
Figure 2.2-1. The relationships among reservoirs and stations based on PCA-ordination of log
(x+l) water quality parameters collected from surface samples, June 1999 to
December 2003 .................................................................................................................. 17
Figure 2.2-2. The median, 5, 25, 75, 95 percentiles and the mean of total dissolved solids,
turbidity, total suspended solids and Secchi Depth in High Rock, Tuckertown,
Narrows and Falls Reservoirs ............................................................................................ 18
Figure 2.2-3. The median, 5, 25, 75, 95 percentiles and the mean of total nitrogen, total
kjeldahl nitrogen, total phosphorus and chlorophyll a in High Rock,
Tuckertown, Narrows and Falls Reservoirs ...................................................................... 19
Figure 2.2-4. Median, 5, 25, 75, and 95 percentiles and mean temperature, pH and dissolved
oxygen in the upper mainstem of High Rock Reservoir, tailraces and reservoir
stations ............................................................................................................................... 20
Figure 2.2-5. The median, 5, 25, 75 and 95 percentiles and the mean of chlorophyll a, nitrate,
total kjeldahl nitrogen and ammonia in the upper mainstem of High Rock
Reservoir, tailraces and reservoir stations ......................................................................... 22
Figure 2.3-1. Temperature and dissolved oxygen profiles in High Rock Reservoir near the
dam from 1999 to 2003 (y axis scale of 170 to 200 meters is equivalent to 558
to 656 feet) ......................................................................................................................... 26
Figure 2.3-2. Temperature and dissolved oxygen profiles in Tuckertown Reservoir near the
dam from 1999 to 2003 (y axis scale of 150 to 180 meters is equivalent to 492
to 591 feet) ......................................................................................................................... 30
Figure 2.3-3 Temperature and dissolved oxygen profiles in Narrows Reservoir near the dam
from 1999 to 2003 (y axis scale of 100 to 160 meters is equivalent to 328 to
525 feet) ............................................................................................................................. 37
Yadkin Project Water Quality Monitoring Study iii Normandeau Associates
Water Quality
Figure 2.3-4. Temperature and dissolved oxygen profiles in Falls Reservoir near the dam
from 1999 to 2003 (y axis scale of 80 to 100 meters is equivalent to 262 to 361
feet) .................................................................................................................................... 39
Figure 2.3-5. Locally weighted estimates (LOWESS) of Total Suspended Solids
concentrations (mg/1) in the upper mainstem of High Rock, the lower mainstem
and arms of High Rock, Tuckertown and Narrows Reservoirs from June 1999 to
December 2003 .................................................................................................................. 43
Figure 2.3-6. Locally weighted estimates (LOWESS) of Total Dissolved Solids
concentrations (mg/1) in the upper mainstem of High Rock, the lower mainstem
and arms of High Rock, Tuckertown and Narrows Reservoirs from June 1999 to
December 2003 .................................................................................................................. 43
Figure 2.3-7. Locally weighted estimates (LOWESS) of Chlorophyll a concentrations (ug/1)
in the upper mainstem of High Rock, the lower mainstem and arms of High
Rock, Tuckertown and Narrows Reservoirs from June 1999 to December 2003........... 45
Figure 2.3-8. Locally weighted estimates (LOWESS) of Total Organic Carbon concentrations
(mg/1) in the upper mainstem of High Rock, the lower mainstem and arms of
High Rock, Tuckertown and Narrows Reservoirs from June 1999. to December
2003 .................................................................................................................................... 45
Figure 2.3-9. Locally weighted estimates (LOWESS) of Total Phosphorus concentrations
(mg/1) in the upper mainstem of High Rock, the lower mainstem and arms of
High Rock, Tuckertown and Narrows Reservoirs from June 1999 to December
2003 .................................................................................................................................... 46
Figure 2.3-10. Locally weighted estimates (LOWESS) of Ammonia-nitrogen concentrations
(mg/1) in the upper mainstem of High Rock, the lower mainstem and arms of
High Rock, Tuckertown and Narrows Reservoirs from June 1999 to December
2003 .................................................................................................................................... 46
Figure 2.3-11. Locally weighted (LOWESS) estimates of Total Kjeldahl-nitrogen
concentrations (mg/1) in the upper mainstem of High Rock, the lower mainstem
and arms of High Rock, Tuckertown and Narrows Reservoirs from June 1999 to
December 2003 .................................................................................................................. 47
Figure 2.3-12. Locally weighted estimates (LOWESS) of Nitrate-nitrogen concentrations
(mg/1) in the upper mainstem of High Rock, the lower mainstem and arms of
High Rock, Tuckertown and Narrows Reservoirs from June 1999 to December
2003 .................................................................................................................................... 48
Figure 2.3-13. Monthly surface and bottom median turbidity (NTtI in the lower mainstem and
arms of High Rock, Tuckertown, Narrows and Falls Reservoirs. Data are from
1999 through 2003 ............................................................................................................. 49
Figure 2.3-14. Monthly surface and bottom median Total Suspended Solids (mg/1) in the lower
mainstem and arms of High Rock, Tuckertown, Narrows and Falls Reservoirs.
Data are from 1999 through 2003 ..................................................................................... 50
Figure 2.3-15. Monthly surface and bottom median Total Phosphorus (mg/1) in the lower
mainstem and arms of High Rock, Tuckertown, Narrows and Falls Reservoirs.
Data are from 1999 through 2003 ..................................................................................... 51
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Water Quality
Figure 2.3-16. Monthly surface and bottom median Ammonia-nitrogen (mg/1) in the lower
mainstem and arms of High Rock, Tuckertown, Narrows and Falls Reservoirs.
Data are from 1999 through 2003 ..................................................................................... 52
Figure 2.3-17. Median monthly Nitrate-Nitrogen concentrations (mg/1) in surface and bottom
collections from the lower mainstem and arms of High Rock and from
Tuckertown, Narrows and Falls Reservoirs. Data are from 1999 through 2003 ............. 53
Figure 2.4-1. Locally weighted estimates (LOWESS) of Temperature °C in High Rock,
Tuckertown, Narrows and Falls tailraces from June 1999 to December 2003 ................ 57
Figure 2.4-2. Locally weighted estimates (LOWESS) of Dissolved Oxygen (mg/1) in High
Rock, Tuckertown, Narrows and Falls tailraces from June 1999 to December
2003 .................................................................................................................................... 57
Figure 2.4-3. Locally weighted estimates (LOWESS) of Chlorophyll a (µg/1) in High Rock,
Tuckertown, Narrows and Falls tailraces from June 1999 to December 2003 ................ 58
Figure 2.4-4. Locally weighted estimates (LOWESS) of Nitrate-Nitrogen (mg/1) in High
Rock, Tuckertown, Narrows and Falls tailraces from June 1999 to December
2003 .................................................................................................................................... 58
Figure 2.4-5. Locally weighted estimates (LOWESS) of Ammonia-Nitrogen (mg/1) in High
Rock, Tuckertown, Narrows and Falls tailraces from June 1999 to December
2003 .................................................................................................................................... 59
Figure 2.4-6. Transect locations in High Rock tailrace to confirm monitor placement ........................ 60
Figure 2.4-7. Transect locations in Tuckertown tailrace to confirm monitor placement ...................... 61
Figure 2.4-8. Transect locations in Narrows tailrace to confirm monitor placement ............................ 62
Figure 2.4-9. Transect locations in Falls tailrace to confirm monitor placement .................................. 63
Figure 2.4-10. Continuous dissolved oxygen and temperature data at High Rock Tailrace
2003-2004 ......................................................................................................................... 65
Figure 2.4-11. Continuous dissolved oxygen and temperature data at Tuckertown Tailrace
2003-2004 ......................................................................................................................... 65
Figure 2.4-12. Continuous dissolved oxygen and temperature data at Narrows Tailrace 2003-
2004 .................................................................................................................................... 66
Figure 2.4-13. Continuous dissolved oxygen and temperature data at Falls Tailrace 2003-2004.......... 67
Figure 2.4-14. Dissolved oxygen (mg/1) in High Rock Reservoir and Tailrace 2001 (horizontal
lines in top panel represent intake interval) (y axis scale of 170 to 200 in is
equivalent to 558 to 656 ft) ............................................................................................... 70
Figure 2.4-15. Dissolved oxygen (mg/1) in High Rock Reservoir and Tailrace 2002 (horizontal
lines in top panel represent intake interval) (y axis scale of 170 to 200 in is
equivalent to 558 to 656 ft) ............................................................................................... 70
Figure 3.3-1. Narrows 2001 Runner Test - Actual 15 Minute Readings ............................................... 87
Figure 3.3-2. Narrows 2001 Runner Test - Average Hourly Flow ........................................................ 88
Figure 3.3-3. Narrows 2001 Runner Test - Average Hourly Generation .............................................. 89
Figure 3.3-4. Narrows 2004 Operations Test - dissolved oxygen and Temperature ............................ 95
Figure 3.3-5. Narrows 2004 Operations Test - Discharge ..................................................................... 95
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Water Quality
Figure 3.3-6. Narrows 2004 Operations Test - Intake dissolved oxygen Profile .................................. 96
Figure 3.3-7. Falls 2004 Operations Test - Dissolved Oxygen and Temperature ............................... .. 98
Figure 3.3-8 Falls 2004 Operations Test - Discharge ......................................................................... .. 98
Figure 3.3-9. Falls 2004 Operations Test - Intake Dissolved Oxygen Profile .................................... .. 99
Figure 3.3-10. Rock 2004 Operations Test - Dissolved Oxygen and Temperature .............................. ..99
Figure 3.3-11. High Rock 2004 Operations Test - Discharge ............................................................... 100
Figure 3.3-12. High Rock 2004 Operations Test - Intake Dissolved Oxygen Profile August 5,
2004 .................................................................................................................................. 100
Figure 3.3-13. High Rock 2004 Operations Test - Intake Dissolved Oxygen Profile August 7,
2004 .................................................................................................................................. 101
Figure 3.3-14. Tuckertown 2004 Operations Test - Dissolved Oxygen and Temperature ................... 102
Figure 3.3-15. Tuckertown 2004 Operations Test - Discharge ............................................................. 102
Figure 3.3-16. Tuckertown 2004 Operations Test - Intake Dissolved Oxygen Profile ........................ 103
Figure 3.4-1. Location of transects/sampling stations for lateral and longitudinal survey of
dissolved oxygen and temperature at High Rock ........................................................... 105
Figure 3.4-2. Location of transects/sampling stations for lateral and longitudinal survey of
dissolved oxygen and temperature at Tuckertown ......................................................... 106
Figure 3.4-3. Location of transects/sampling stations for lateral and longitudinal survey of
dissolved oxygen and temperature at Narrows ............................................................... 107
Figure 3.4-4. Location of transects/sampling stations for lateral and longitudinal survey of
dissolved oxygen and temperature at Falls ..................................................................... 108
Figure 3.4-5. Temperature and dissolved oxygen at Transect I Station B, Narrows
impoundment (y axis scale of 0-50 meters is equivalent to 0-164 feet) ........................ 115
Figure 3.5-1. Average TSS Concentration vs. Distance Downstream of HI, June 1999
through 2003 .................................................................................................................... 117
Figure 3.5-2. Range in TSS Values vs. Distance Downstream of HI, June 1999 through 2003........ 119
Figure 3.5-3. Daily Inflow to High Rock Reservoir and Average TSS Concentration at Station
HI High Rock Reservoir, June 1999 through 2003 ........................................................ 120
Figure 3.5-4. Average percent change in TSS concentration by impoundment and
cumulatively, June 1999 through 2003 ........................................................................... 122
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Water Quality
List of Tables
Page
Table 1.0-1. Characteristics of the four Yadkin APGI reservoirs and projects ...................................... 2
Table 2.1-1. Sampling locations of the current study in the four reservoirs of the Yadkin
Project ................................................................................................................................ 12
Table 2.1-2. Selected water quality parameters, the EPA method and detection limit ........................ 14
Table 2.3-1. Median values of water quality parameters from June 1999 to December 2003
at each High Rock Reservoir station ................................................................................. 23
Table 2.3-2. Dissolved oxygen characteristics of stations in High Rock Reservoir ............................. 27
Table 2.3-3. Median values of water quality parameters from June 1999 to December 2003
at each station in Tuckertown, Narrows and Falss Reservoirs ......................................... 29
Table 2.3-4. Temperature profiles in Lick Creek, Lick Creek Arm and upper Tuckertown
Reservoir from July to December 2003 ............................................................................ 32
Table 2.3-5. Dissolved oxygen profiles in Lick Creek, Lick Creek Arm and upper
Tuckertown Reservoir from July to December 2003 ....................................................... 33
Table 2.3-6. Monthly water quality in Lick Creek and the median from Lick Creek and
Tuckertown Reservoir from July to December 2003 ....................................................... 34
Table 2.3-7. The number of sampling dates when concentrations of nitrite, chemical oxygen
demand and toxic substances were above the detection limit in either the surface
or bottom samples at each station from June 1999 to December 2003 ............................ 35
Table 2.4-1. Summary of monthly water quality monitoring data in tailraces (1999-2003) ............... 55
Table 2.4-2. Dates of continuous tailrace monitoring in four Yadkin Project tailraces, 2000-
2004 .................................................................................................................................... 59
Table 2.4-3. Number of monitored days each project tailrace was below specific dissolved
oxygen concentrations ....................................................................................................... 68
Table 2.5-1. Parameters measured in this study that have applicable North Carolina Water
Quality Standards ............................................................................................................... 72
Table 2.5-2. Number of samples that exceeded state standards for chlorophyll a, turbidity,
total dissolved solids, cadmium, copper, cyanide, lead and mercury during the
monthly water quality monitoring program (1999-2003) ................................................ 73
Table 2.5-3. Number of measurements that exceeded state standards for temperature,
dissolved oxygen and pH during the monthly water quality monitoring program
(1999-2003) ....................................................................................................................... 74
Table 2.5-4. Comparison of historical water quality data with current data ......................................... 77
Table 3.1-1. Kendall's tau correlation coefficients of weekly average flow versus water
quality parameters in the reservoirs and tailraces .t ........................................................... 81
Table 3.2-1. Correlation coefficients (p <0.05, 95% significance) of water level versus
surface water quality parameters throughout the Yadkin system. Significant
correlations are noted in bold type .................................................................................... 84
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Table 3.3-1. Summaries of Dissolved Oxygen Observations During August, 2001 Testing .............. 86
Table 3.3-2. Dissolved Oxygen Concentrations at Selected Locations Upstream of Narrows
During the Time Frame of the August 2001 Testing ...................................................... .. 90
Table 3.3-3. August 2004 Operations Testing - Narrows Configuration and Results ....................... .. 94
Table 3.4-1. Schedule for lateral and longitudinal survey of dissolved oxygen and
temperature after 6 hours of full generation, August 20, 2004 . ..................................... 109
Table 3.4-2. Schedule for lateral and longitudinal survey of dissolved oxygen and
temperature after 6 hours with no generation, August 21, 2004 . ................................... 109
Table 3.4-3. Depth to intakes from normal full pond elevation .......................................................... 109
Table 3.4-4. Summary of lateral and longitudinal dissolved oxygen and temperature results
(minimum, maximum and mean values in profiles) at High Rock project.
August 20-21, 2004 ......................................................................................................... I I I
Table 3.4-5. Summary of lateral and longitudinal dissolved oxygen and temperature results
(minimum, maximum and mean values in profiles) at the Tuckertown project,
August 20-21, 2004 ......................................................................................................... I I I
Table 3.4-6. Summary of lateral and longitudinal dissolved oxygen and temperature results
(minimum, maximum and mean values in profiles) at the Narrows project.
August 20-21, 2004 . ........................................................................................................ 112
Table 3.4-7. Summary of lateral and longitudinal dissolved oxygen and temperature results
(minimum, maximum and mean values in profiles) at the Falls project. August
20-21,2004 . ..................................................................................................................... 112
Table 3.4-8. Depth to 5 mg/1 dissolved oxygen contour in Yadkin Project Impoundments
during lateral and longitudinal surveys. August 20-21, 2004 . ...................................... 113
Table 3.5-1. Summary of Average Annual TSS Concentration (mg/L) for Monitoring
Stations along the Mainstem of the Yadkin River from June 1999 through 2003........ 121
Table 3.6-1. The concentration of mercury in fish tissue of largemouth bass, black crappie
and channel catfish collected in Tuckertown tailrace (upper Narrows reservoir)
September 1-3, 2003 ........................................................................................................ 124
Table 3.6-2 Fecal coliform data collected by NCDENR in the Yadkin reservoirs ........................... 125
Yadkin Project Water Quality Monitoring Study viii Normandeau Associates
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List of Appendix Tables
Appendix A Yadkin Monitoring Program Missing Data and Observations by Field Personnel
Appendix B Monthly Water Quality Data 1999-2003
Appendix C PCA Results
Appendix D High Rock Reservoir Dissolved Oxygen Contour Plots
Appendix E Narrows Reservoir Dissolved Oxygen Contour Plots
Appendix F Surface and Bottom Monthly Concentrations of Total Dissolved Solids, Biological
Oxygen Demand, Total Kjeldahl Nitrogen and Total Organic Carbon
Appendix G Continuous Tailrace Monitor Performance Data
Appendix H Dissolved Oxygen and Temperature Data from Tailrace Transect Surveys (Narrows
and Falls 2001, High Rock and Tuckertown 2003)
Appendix I Continuous Tailrace Monitoring Data
Appendix J Instances When State Standards for Temperature, Lead, Cadmium and Total
Dissolved Solids were Exceeded
Appendix K Data and Contour Plots for Lateral and Longitudinal Dissolved Oxygen and
Temperature Surveys
Appendix L Kendall's Tau Correlation Coefficients for Daily Average Flow Versus Water
Quality Parameters
Appendix M Water Quality Comment Summary
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SUMMARY
The Water Quality Monitoring Report summarizes the results of five years of water quality
monitoring that has been conducted in the four Yadkin Project reservoirs and tailwaters. The water
quality monitoring and the analysis of water quality conditions were conducted by Normandeau
Associates, Inc. (NAI) as part of the FERC relicensing process for the Yadkin Project. The water
quality data analysis and report were prepared in accordance with the Final Water Quality Monitoring
Study Plan that was developed by Yadkin in consultation with the Water Quality Issue Advisory
Group (IAG). Specific objectives identified in the Final Study Plan included:
¦ Continue the collection of reservoir water quality data at sampling stations used in previous years
in order to characterize the baseline water quality of the four Project reservoirs and four tailwater
areas.
Evaluate the effects of current Project operations, including reservoir water level fluctuations on
reservoir water quality.
Conduct continuous monitoring of dissolved oxygen (DO) and temperature conditions in all four
Project tailwaters during the warm water months (May through November) in order to evaluate
existing water quality conditions in the tailwaters and how these conditions may be affected by
Project operations.
NAI has been collecting water quality data at the Yadkin Project since June 1999. Monthly water
quality sampling has been conducted at 16 reservoir locations and at each of the four tailraces below
the dams. In addition, the tailraces of the Falls and Narrows developments were continuously
monitored for dissolved oxygen and temperature for extended periods in 2000-2004. The tailraces of
the High Rock and Tuckertown developments were continuously monitored for dissolved oxygen and
temperature for extended periods in 2003-2004. Yadkin's five year water quality monitoring effort is
summarized in the table below.
In terms of general trends in Project water quality, the results of the monitoring study showed the
Yadkin Project waters experience varying degrees of eutrophication as a result of elevated
concentrations of nutrients and chlorophyll a (an indicator of algal growth) and reduced levels of
dissolved oxygen. Among the four Project reservoirs, water quality is generally poorest in the High
Rock Reservoir and best in Falls Reservoir. Concentrations of nutrients, suspended solids and
chlorophyll were all found on average to decrease from High Rock downstream through Falls
Reservoir. In High Rock Reservoir itself, water quality in several of the tributary arms, particularly
the Swearing Creek, Crane Creek and Abbotts Creek arms, was somewhat poorer than that observed
in the mainstem of the reservoir.
Of the four Project reservoirs, only Narrows was found to experience strong seasonal thermal
stratification. Coincident with the thermal stratification, top to bottom differences in reservoir
dissolved oxygen concentrations are significant at Narrows during much of the summer and fall. High
Rock and Tuckertown Reservoirs were found to weakly stratify during some periods of the summer
and top to bottom dissolved oxygen concentrations are variable for much of the summer. Falls
Reservoir experiences no thermal stratification.
There are also water quality concerns in the Yadkin Project tailwaters, located immediately
downstream of the dams. The primary water quality concern in the tailwaters is the concentration of
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Summary of Water Quality Monitoring Conducted by APGI at the Yadkin Project
Monitoring Location 1999 2000 2001 2002 2003 2004
High Rock Reservoir Monthly Monthly Monthly Monthly Monthly
10 stations Jun-Dec Jan-Dec Jan-Dec Jan-Dec Jan-Dec
Tuckertown Reservoir Monthly Monthly Monthly Monthly Monthly
2 stations Jun-Dec Jan-Dec Jan-Dec Jan-Dec Jan-Dec
Narrows Reservoir Monthly Monthly Monthly Monthly Monthly
3 stations Jun-Dec Jan-Dec Jan-Dec Jan-Dec Jan-Dec
Falls Reservoir Monthly Monthly Monthly Monthly Monthly
1 station Jun-Dec Jan-Dec Jan-Dec Jan-Dec Jan-Dec
High Rock Tailwater Monthly Monthly Monthly Monthly Monthly Continuous
1 station Jun-Dec Jun-Dec Jun-Dec Jun-Dec Jan-Dec DO/Temp
Continuous May-Nov
DO/Temp
May-Nov
Tuckertown Tailwater Monthly Monthly Monthly Monthly Monthly Continuous
1 station Jun-Dec Jun-Dec Jun-Dec Jun-Dec Jan-Dec DO/Temp
Continuous May-Nov
DO/Temp
May-Nov
Narrows Tailwater Monthly Monthly Monthly Monthly Monthly Continuous
1 station Jan-Dec Jan-Dec Jan-Dec Jan-Dec Jan-Dec DO/Temp
Continuous Continuous Continuous May-Nov
DO/Temp DO/Temp DO/Temp
May-Nov May-Nov May-Nov
Falls Tailwater Monthly Monthly Monthly Monthly Monthly Continuous
1 station Jan-Dec Jan-Dec Jan-Dec Jan-Dec Jan-Dec DO/Temp
Continuous Continuous Continuous May-Nov
DO/Temp DO/Temp DO/Temp
May-Nov May-Nov May-Nov
dissolved oxygen. The water quality monitoring study found that dissolved oxygen levels in the all
four project tailwater areas are frequently at or below the state standards throughout much of the
summer and fall (May through November). Low dissolved oxygen concentrations in the tailwaters is
a result of the release of low dissolved oxygen reservoir water into the tailrace. Elevated
concentrations of nutrients, organic matter and algae found in the tailwater areas also contribute to
this problem.
The study examined the influence of flows through the Project on water quality. For a large reservoir
like High Rock, retention time can vary considerably depending of flow conditions. At High Rock
estimated retention times average between 4 and 50 days, depending on river flows. At Narrows the
average retention time is estimated to be about 2 days. At the two smaller reservoirs, Tuckertown and
Falls, the average retention time is estimated to be about 22 hours and 2 hours, respectively. Longer
reservoir retention times such as those experienced by High Rock and, to a lesser extent Narrows,
have the effect of allowing algae to utilize available nutrients and to grow in greater concentrations.
From this perspective, flow in the Yadkin River has a strong influence on the water quality of the
upper portion of High Rock Reservoir where the study recorded low levels of chlorophyll a (an
indicator of algal concentrations) in the presence of high nutrient concentrations. This is a condition
that would be expected in a riverine environment where most of the algae is attached to substrates and
not present in the open water. The upper portion of High Rock Reservoir was also observed to have
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high concentrations of suspended solids which limit light availability to algae. Based on the water
quality data collected, the "riverine" effects of the mainstem Yadkin River on water quality
conditions were observed to at least six miles along the mainstem in the upper portion of High Rock
Reservoir.
The study also examined whether flow through the Project developments affects water quality. This
study examined the relationship of flows and water quality statistically through the use of correlation
analysis. Results of a correlation analysis between flows at each of the dams with water quality
suggest that in general water quality conditions are weakly correlated with flows. Overall, observed
relationships between flows and water quality were primarily related to retention time in the
reservoirs and transport and deposition of suspended solids.
The study also examined the potential influence of reservoir water levels on both reservoir and
tailwater water quality conditions. In terms of the influence of reservoir water levels on reservoir
surface water quality, correlation results were generally poor. NAI found that most correlation
coefficients (which express the strength of the relationship between the factors being correlated) were
low indicating that poor, if any, relationships exist between reservoir water levels and water quality.
In general, where correlations were observed, they were negative indicating that at lower reservoir
water levels, concentrations of the water quality parameter tend to be higher, an effect that may also
be caused by seasonal changes in reservoir water quality as by reservoir water levels. In High Rock
Reservoir, which experiences the greatest changes in reservoir water levels, the strongest correlations
to water levels were seen in total dissolved solids and total phosphorus concentrations, which were
both negatively correlated with reservoir water levels; meaning that the concentrations of those
parameters were higher at lower water levels.
The influence of Project operations on tailwater dissolved oxygen levels was another important issue
addressed by this study. Modifications to Narrows Unit 4 in 2001 included the addition of two air
injection valves intended to introduce air into the flow during generation. The ability of the Unit 4
aeration valves to increase tailwater dissolved oxygen concentrations was the subject of an earlier
study conducted by APGI and reported to FERC (NAI, 2002). In this study, additional testing was
done to further examine the effect of project operations on tailwater dissolved oxygen. The
objectives of the additional testing were:
To further evaluate the effectiveness of the air injection valves at Narrows Unit 4 to increase
tailwater dissolved oxygen levels,
¦ To determine how increases in dissolved oxygen concentrations in the Narrows tailwater impact
the dissolved oxygen concentrations in the Falls tailwater, and
¦ To determine if an increase in dissolved oxygen concentrations in the High Rock taillwater
impacts the dissolved oxygen concentration in the Tuckertown tailwater.
The additional tailwater DO testing was scheduled for August and September of 2004. However,
high flows due to successive hurricanes in September forced APGI to cancel the September test, so
only the August tests were completed. At Narrows, tests of the effect of the two aeration valves on
Unit 4 generally confirmed earlier results (2001) that with both valves operating and just Unit 4
operating, about 2 mg/1 of dissolved oxygen is added to the tailwaters. The tests also demonstrated
that increases in Narrows tailwater dissolved oxygen levels are generally translated to similar
increases in dissolved oxygen concentrations below Falls dam. This result supports the conclusion
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that if dissolved oxygen levels in the Narrows tailwaters are raised, similar increases in Falls tailwater
dissolved oxygen concentrations would be expected.
Tailwater testing in the High Rock tailwater focused on determining if increasing High Rock tailwater
dissolved oxygen concentrations would result in an observable increase in dissolved oxygen levels in
the Tuckertown Reservoir. Since there is currently no aeration equipment in place at High Rock,
APGI attempted to raise High Rock tailwater dissolved oxygen levels temporarily by operating the
High Rock units at a unusually low gated setting that was hoped would allow maximum air intake
through an existing system of piping and valves through the bearing riser.' Despite APGI's best
efforts no significant increase in High Rock tailwater dissolved oxygen concentrations were observed
to occur during the test. Dissolved oxygen concentrations did increase somewhat over the three-day
test period, but NAI concluded that this increase was the result of improved reservoir dissolved
oxygen conditions and diurnal cycles in the dissolved oxygen and temperature rather than air
introduced through the High Rock units. As the test failed to produce a significant increase in High
Rock tailwater dissolved oxygen concentrations, not surprisingly there was no measurable response in
dissolved oxygen levels in the Tuckertown tailwater.
Finally, the water quality monitoring study examined a couple of biological water quality issues that
were raised by the Water Quality JAG. The question of mercury in fish tissue was examined in the
study by collecting fish tissue samples in several locations throughout the Project. Fish were captured
by NAI using a combination of gill nets and electrofishing. Mercury concentrations in all of the fish
samples collected were below the detection limit of 0.145 mg/kg, which is well below the U.S.
Environmental Protection Agency's action level of I mg/kg.
Concerns about levels of fecal coliform in the Project waters were also addressed in this study.
Monitoring for fecal coliform in the Project reservoirs is handled by both the North Carolina Division
of Water Quality and, as needed, by the local county health departments. In this study NAI compiled
fecal coliform data that had been collected in High Rock, Tuckertown and Narrows reservoirs for the
years 1999 to 2001. For the most part fecal coliform counts were generally less than 10 per 100 ml.
All of the samples had concentrations below the State standard for Class C waters of 200 per 100 ml.
' This method of operation can only be used on a short-term basis. Long-term operation of the High Rock
units in this manner would result in damage to the units.
Yadkin Project Water Quality Monitoring Study Xiii Normandeau Associates
Water Quality
1.0 INTRODUCTION
Alcoa Power Generating Inc. is currently licensed by the Federal Energy Regulatory Commission to
operate four hydroelectric facilities (FERC No. 2197 NC) on the Yadkin River in central North
Carolina. The current license will expire in 2008. To continue operations, Alcoa has applied for a
new license. As part of the relicensing process, Alcoa sought comment from agencies, municipalities,
organizations and the public on concerns related to the water quality at the Project. The principal
concerns are the current status of water quality in the reservoirs and tailwaters and the effects of
hydroelectric facility operations on water quality. Alcoa initiated water quality monitoring in the
reservoirs and tailwaters in 1999 to establish baseline water quality conditions and assess the current
status of water quality. Additional studies have been conducted through 2004 (Normandeau 2001,
2003, 2004). Water quality study results through 2001 are summarized in Normandeau 2002 and
APGI 2002. Manipulations of flow rate, generation, spill and lake level during the operation of the
hydroelectric facilities may influence water quality.
The four hydroelectric facilities that are currently licensed are High Rock, Tuckertown, Narrows, and
Falls. All four developments are located on a 38-mile stretch of the Yadkin River and support the
electric power needs of Alcoa's Badin Works or sold on the open market. The plants are generally
operated during peak power hours. During periods of high inflow, the system is operated
continuously. The High Rock and Narrows Reservoirs are storage facilities that are operated in a
store and release mode, with storage volumes of 234,863 and 128,926 acre-feet, respectively. The
Tuckertown and Falls developments have storage volumes of 6,897 and 1,825 acre-feet, respectively,
and are operated as essentially run-of-river. The uppermost development, High Rock, serves as the
principal storage facility for the Yadkin/Pee Dee River. The characteristics of the four Project
impoundments and facilities are summarized in Table 1.0-1.
The area immediately surrounding the reservoirs is predominately rural, although several small cities,
including Albemarle, Badin, Lexington, and Salisbury are located within 30 miles. Farms and
timberlands are predominant in this area, but residential development, particularly along the reservoir
shorelines, has increased significantly in the last 10 years. The two largest reservoirs, High Rock and
Narrows, have considerable development along the shoreline and receive significant levels of
recreational use. The two smaller reservoirs, Falls and Tuckertown, have shorelines that are generally
undeveloped and receive less recreational use (Yadkin, Inc., 1999).
The Yadkin River watershed has a drainage area of 4,190 square miles above Falls Dam. The
drainage area is located primarily in the northern piedmont of North Carolina, with a small portion
extending into southern Virginia. The predominant land use has historically been agriculture and
forestry. Currently, land use within the watershed is approximately 58% forested, 31% agricultural,
7% urban, and about 4% rangeland (NCDEM Report NO. 89-04). Some of North Carolina's largest
cities, including Charlotte, Winston-Salem, and Greensboro, are located within an hour of travel time.
Average rainfall in the Yadkin basin ranges between 44 to 56 inches per year. The Yadkin River rises
in the Appalachian Mountains in North Carolina and picks up additional tributaries as it flows parallel
to the mountains in a northeasterly direction. Northwest of Winston-Salem, the river turns south and
flows through flatter terrain until it enters High Rock Reservoir, the most upstream of the four
developments. A major tributary, the South Yadkin River, joins the mainstem of the Yadkin River
north of Salisbury in Rowan County, a short distance upstream of High Rock Reservoir. Other major
tributaries draining into the four reservoirs include Abbotts Creek, Swearing Creek, Dutch Second
Yadkin Project Water Quality Monitoring Study I Normandeau Associates
Water Quality
Table 1.0-1. Characteristics of the four Yadkin APGI reservoirs and projects.
Surface Intake Elevation

roject Area at
Full
Pond
(acres)
Maximum
Reservoir and
(Mean) depth Normal
Full
Pond
Elevation

o

Center
Line

ottom
Number
of Units
Operating Normal
Hydraulic
Capacity
(cfs)
High Rock 15,180 19 (5) m 190.2 m 184.7 m 179.1 m 173.4 m
62.3 (16.4) ft 624.0 ft 606.0 ft 587.6 ft 568.9 ft 1 2,597
2 5,193
3 7,790
Tuckertown 2,560 17 (5) m 172.2 m 162.3 m 158.2 m 154.0 m
55.8 (16.4) ft 565.0 ft 572.5 ft 519.0 ft 505.2 ft 1 2,673
2 5,347
3 8,020
Narrows 5,355 53 (14) m 155.4 m 146.0 m 140.6 m 135.3 m
173.9 (45.9) ft 509.8 ft 479.0 ft 461.3 ft 443.9 ft 1 1,947
2 3,893
3 5,840
4 8,185
Falls 204 16 (8) m 101.5 m 99.3 m 94.5 m 89.6 m
52.5 (26.2) ft 333.0 ft 325.8 ft 310.0 ft 294.0 ft 1 2,608
2 5,215
3 7,455
Creek, Crane Creek, Flat Swamp Creek and Panther Creek which drain into High Rock Reservoir;
Lick Creek, Cabin Creek, Flat Creek, Ellis Creek and Riles Creek which drain into Tuckertown
Reservoir; and Beaver Dam Creek along with Garr Creek which discharge into Narrows Reservoir.
There are no tributaries of significant size that drain to Falls Reservoir. The Yadkin River and its
tributaries are part of the Yadkin-Pee Dee River Basin, which extends from the eastern slopes of the
Blue Ridge Mountains to the Atlantic coast near Georgetown, South Carolina. The Yadkin River's
name changes to the Pee Dee River at its confluence with the Uwharrie River. The Pee Dee River
continues its southeastern flow to Winyah Bay, where it meets the Atlantic Ocean.
Hydrometeorologic Conditions
Critical to understanding the water quality dynamics in the tailraces of the dams in the Yadkin system
are the hydrometeorologic conditions throughout the sampling period. Total flow from the Yadkin
and South Yadkin rivers above High Rock Lake is presented in Figure 1.0-1 for the period 1999
through 2004. The monitoring program at Falls and Narrows encompassed several years with very
different hydrometeorologic conditions. Flows during the sampling years 2000 and 2001 were lower
than average, but 2002 was an extremely dry year, particularly during the summer. 2003 was an
abnormally wet year. Average flows returned in 2004 with the exception of two hurricanes in August
and September that temporarily increased flows and flushed water through the reservoirs, breaking
thermal stratification and replenishing dissolved oxygen in deeper waters. Impoundment water levels
also fluctuated throughout the study period. Daily water levels through 2004 are presented in Figures
1.0-2 through 1.0-5. Long-term average water levels are also included. Pool levels in Tuckertown
and Falls fluctuated little throughout the monitoring period while pool levels in High Rock and
Yadkin Project Water Quality Monitoring Study 2 Normandeau Associates
10000C
U 1000C
w
cD
Q
U
?2 1000
0
W 10C
Figure 1.0-1. Inflow to High Rock Reservoir, 1999-2004.
Q
m
c
n
0
ca'
<D
H

CD
A
c
as
r
q
Jan reb I Mar Apr May I Jun Jul Aug I Sep I Uct NOV Uec
MONTH
YEAR: 1999 2000 2001
2002 2003 2004
AVERAGE
D
D
A
0
M
D
M
A
p
c
D
0
0
Z
0
0
Z
U)
c

Z
0
Q
m
c
n
0
<D
H
HIGH ROCK
192
191
190
189
75 188
Z
O
181
Q
J 186
W
185
184
183
182
Jan I Feb I Mar I Apr I May I Jun I Jul I Aug I Sep I Oct I Nov I Dec
YEAR: 1999 2000
2002 2003
AVERAGE
2001
2004
Figure 1.0-2. High Rock water level 1999 - 2004 (y axis scale of 182 to 192 meters is equivalent to 597 to 630 feet).

CD
A
c
as
r
q
D
D
A
0
M
D
M
A
p
c
D
0
0
Z
0
0
Z
U)
c
Ch
Z
0
Q
m
c
n
0
<D
H
TUCKERTOWN
18(
179
178
177
75 176
Z
O
175
Q
J 174
W
173
172
171
170
Jan I Feb I Mar I Apr I May I Jun I Jul I Aug I Sep I Oct I Nov I Dec
YEAR: 1999 2000
2002 2003
AVERAGE
2001
2004
Figure 1.0-3. Tuckertown water level, 1999 - 2004 (y axis scale of 170 to 180 meters is equivalent to 558 to 591 feet).

CD
A
c
as
r
q
D
D
A
0
M
D
M
A
p
c
D
0
0
Z
0
0
Z
c

Z
0
Q
m
c
n
0
<D
H
NARROWS
160
159
158
157
75 156
O
P: 155
Q
J 154
W
153
152
151
150
T FULL POND
Jan I Feb I Mar I Apr I May I Jun I Jul I Aug I Sep I Oct I Nov I Dec
YEAR: 1999 2000
2002 2003
AVERAGE
2001
2004
Figure 1.0-4. Narrows water level, 1999 - 2004 (y axis scale of 150 to 160 meters is equivalent to 492 to 525 feet).

CD
A
c
as
r
q
D
D
A
0
M
D
M
A
p
c
D
0
0
Z
0
0
Z
U)
c

Z
0
Q
m
c
n
0
<D
H
FALLS
105
104
103
102
75 101
Z
O
100
Q
J 99
W
98
97
96
95
Jan I Feb I Mar I Apr I May I Jun I Jul I Aug I Sep I Oct I Nov I Dec
YEAR: 1999 2000
2002 2003
AVERAGE
2001
2004
Figure 1.0-5. Falls water level, 1999 - 2004 (y axis scale of 95 to 105 meters is equivalent to 312 to 344 feet).

CD
A
c
as
r
q
Water Quality
Narrows exhibited significant fluctuations, particularly in 2002, the drought year. This impact of
these fluctuations on dissolved oxygen and other water quality parameters in the reservoirs and
tailraces is discussed throughout this report.
Yadkin Project Water Quality Monitoring Study 8 Normandeau Associates
Water Quality
2.0 CURRENT STATUS OF WATER QUALITY IN THE RESERVOIRS AND
TAILRACES (1999-2003)
2.1 METHODS
Water Quality Monitoring
To assess the current status of water quality in the four Alcoa reservoirs on the Yadkin River, twenty
stations were selected for monthly sampling. A station was located in the tailrace of each of the four
dams (Figures 2.1-1 and 2.1-2; Table 2.1-1). Ten stations were located in High Rock Reservoir,
including Station H1 near the entrance of the Yadkin River into the reservoir. Due to its dendritic
shape, stations were located in the major reservoir arms and along the mainstem reservoir channel.
Two stations were sampled in Tuckertown Reservoir. Three stations were sampled in Narrows
Reservoir, including one station in the reservoirs major arm. One station was sampled in Falls
Reservoir. A Station (T4) was added in Lick Creek upstream of its confluence with Tuckertown
Reservoir in July 2003 (Figure 2.1-3). Additional dissolved oxygen and temperature measurements
were collected at two sites in the Lick Creek Arm of Tuckertown Reservoir and at seven stations
below the High Rock Dam tailrace in the upper portion of Tuckertown Reservoir beginning in July
2003.
Stations were sampled monthly from June 1999 to December 2003. On each collection date,
temperature, pH, dissolved oxygen and specific conductance were measured in situ using a calibrated
YSI 6920 field meter at one meter intervals from the surface to the bottom. Beginning in April 2001,
turbidity was also measured in situ at one meter intervals. To determine the vertical distribution of
nutrients, solids and metals under stratified and unstratified conditions, surface and bottom samples
were collected monthly at each station. From June 1999 to January 2001, surface samples were
collected by immersing the sampling bottle below the surface. Beginning in February 2001, a
composite sample of the photic zone, defined as twice the Secchi transparency depth, replaced the
surface grab sample for all chemical parameters except for metals. The composite sample was
collected by a pump and hose that was lowered through the photic zone at a constant rate. Bottom
samples were collected using a pump and hose, except for Station N4 where a Van Dorn Bottle was
used. Chlorophyll a samples were only collected from the photic zone. Secchi transparency was
measured at each station. A list of the chemical parameters analyzed in the laboratories and their
detection limits are presented (Table 2.1-2). All sampling and analysis was conducted in accordance
with North Carolina water quality monitoring protocols and procedures (NCDEM 2004). Notes from
field personnel and a list of missing data are presented in Appendix A.
Data Analysis
All water quality data was entered or imported into a SAS database (SAS 2004). Monthly water
quality data is presented in Appendix B stations within each reservoir were compared by tabulating
median values. The median was used, rather than the mean, because the median is more resistant to
extreme values. As is typical in water quality data, most of the parameters measured in this study had
skewed distributions. Also, the median is a more appropriate measure of central tendency when some
of the results are reported as below a detection limit (Helsel and Hirsch, 1991). Variability was
assessed by plotting quartiles and the 5 and 95 percentiles of the data. All stations and sampling dates
were used to compute the medians and percentiles for each reservoir.
Yadkin Project Water Quality Monitoring Study 9 Normandeau Associates
Water Quality
Figure 2.1-1. Upper Impoundments and Sampling Stations.
Yadkin Project Water Quality Monitoring Study 10 Normandeau Associates
Water Quality
Rowan County
Montgomery County
r
T3
Tuckertownk NI
Dam
3tanly County
1

VII
?tl+l
L?
¦N3
t
I
t Narrow.,;
1 ` Rcservorr
Narrows Dam
F1
?pyN$Ifl
County Boundary
• Sampling Locations
Hydrography
September 2002
Water Quality Sampling Stations
in Falls and Narrows Reservoirs
Yadkin Project
(2 of 2)
N
W+E
s
1 05 0 1 Miles
Dam
Figure 2
Figure 2.1-2. Lower Impoundments and Sampling Stations.
Yadkin Project Water Quality Monitoring Study I I
Normandeau Associates
Water Quality
Table 2.1-1. Sampling locations of the current study in the four reservoirs of the Yadkin
Project.
Station Station Description StationType WaterBody Lat/Long
Hl Upper High Rock Reservoir near the mouth of Yadkin Reservoir High Rock N 35 43 23.113
River Mainstem Reservoir W 80 23 28.829
H2 Upper High Rock Reservoir/Swearing Creek Arm Reservoir High Rock N 35 41 29.732
Arm Reservoir W 80 18 06.378
H3 Upper High Rock Reservoir middle of Section 3 Reservoir High Rock N 35 40 24.383
Mainstem Reservoir W 80 19 19.823
H4 Upper High Rock Reservoir/Crane Creek Arm Reservoir High Rock N 35 39 49.391
Arm Reservoir W 80 21 13.557
H5 High Rock Reservoir/Upper Abbotts Creek Arm Reservoir High Rock N 35 40 35.077
Arm Reservoir W 80 15 01.513
H6 High Rock Reservoir/Lower Abbotts Creek Arm Reservoir High Rock N 35 38 33.445
Arm Reservoir W 80 15 15.309
H7 High Rock Reservoir middle of Section 2 Reservoir High Rock N 35 38 09.509
Mainstem Reservoir W 80 17 23.973
H8 High Rock Reservoir/Second Creek Arm Reservoir High Rock N 35 36 32.056
Arm Reservoir W 80 18 22.933
H9 High Rock Reservoir/Flat Swamp Creek Arm Reservoir High Rock N 35 37 36.284
Arm Reservoir W 80 12 28.825
H10 High Rock Reservoir near Dam Reservoir High Rock N 35 36 08.535
Mainstem Reservoir W 80 14 06.263
TI High Rock Dam Tailrace Tailrace Tuckertown N 35 35 48.279
Reservoir W 80 13 54.184
T2 Tuckertown Reservoir at middle constriction Reservoir Tuckertown N 35 32 40.214
Reservoir W 80 11 55.960
T3 Tuckertown Reservoir near Dam Reservoir Tuckertown N 35 29 09.958
Reservoir W 80 10 37.942
T4 Lick Creek Stream Lick Creek N 35 36 58.900
W 80 10 32.200
NI Tuckertown Dam Tailrace Tailrace Narrows Reservoir N 35 29 01.739
W 80 10 21.234
N2 Narrows Reservoir middle of Section 3 Reservoir Narrows Reservoir N 35 27 53.724
W 80 07 23.843
N3 Narrows Reservoir by Gladys Fork Reservoir Narrows Reservoir N 35 27 58.795
Arm W 80 05 16.426
N4 Narrows Reservoir near Dam Reservoir Narrows Reservoir N 35 25 16.385
W 80 05 36.485
Fl Narrows Dam Tailrace Tailrace Falls Reservoir N 35 25 05.637
W 80 05 28.767
F2 Falls Reservoir near Dam Reservoir Falls Reservoir N 35 23 43.671
W 80 04 36.692
F3 Falls Dam Tailrace Tailrace Yadkin River/ N 35 23 28.734
Lake Tillery W 80 04 14.938
Yadkin Project Water Quality Monitoring Study 12 Normandeau Associates
Water Quality
Figure 2.1-3. Lick Creek and Tuckertown Reservoirs. Supplemental water quality stations.
Yadkin Project Water Quality Monitoring Study 13 Normandeau Associates
Water Quality
Table 2.1-2. Selected water quality parameters, the EPA method and detection limit.
Parameter EPA Method Detection Limit Units
Chlorophyll a SM 10200H #2 0.2 /l
Alkalinity, Total SM 2320B mg/1
Biological Oxygen Demand 405.1 2 mg/1
Cadmium 200.8/6020 0.5 µg/l
Carbon, Total Organic SM 5310C/9060 mg/1
Chemical Oxygen Demand 410.4/7196 20 mg/1
Copper 200.8/6020 10 µg/1
Cyanide, Total 335.4/9012 0.005 mg/1
Lead 200.8/6020 2 µg/l
Mercury 245.1/7470A 0.2 ?tg/l
Nitrogen, Ammonia 350.1 0.05 Mg/1
Nitrogen, N03+NO2(as N) 353.2/9200 0.05 mg/1
Nitrogen, Total Kjeldahl 351.2 0.5 mg/1
Phosphorus, Total SM4500-P-E2 0.02 mg/1
Residue, Total 160.3 20 mg/1
Residue, Filterable 160.1 20 mg/1
Residue, Nonfilterable 160.2 5 mg/1
For analytical purposes, tailrace stations (T1, N1, F1, F3) were analyzed separately from the reservoir
stations. Median values computed for tailrace stations were not included in reservoir averages.
Mainstem and arm stations from High Rock Reservoir were presented separately. Temperature and
dissolved oxygen profiles were presented as contour plots of depth by month for stations near the
dams in each reservoir.
Reservoirs are complex systems with a variety of physical and biological processes occurring
simultaneously. To identify the relationships among the stations and reservoirs and determine the
factors that have the most influence on the system, a Principal Component Analysis (PCA) -ordination
was performed on water quality parameters from surface collections (Clarke and Warwick, 1994).
Bottom samples were not included in the PCA-ordination because the effects of bottom-typical
dissolved oxygen depletion could possibly obscure other trends. PCA-ordination was used to plot the
position of individual station on the axis that account for the greatest amount of variation in the data.
This essentially creates a map of the differences among stations. Stations that are located in close
proximity on the PCA plot are more similar to each other than stations that are plotted further away.
Underlying factors were determined based on the distribution of stations. The responses of individual
parameters on each principal component was determined. The PCA-ordination is based on overall
station means. Mean values for each station were computed after a log(x+l) transformation was
applied to the monthly data. Because units are not similar, the data were standardized prior to
analysis. Surface dissolved oxygen, temperature, pH and conductivity were computed from the 1-
meter profile depth for the PCA-ordination. To illustrate the results of the PCA, Box-plots along with
the 5% and 95% percentiles were plotted for groups defined by the principal component axes. The
parameters that were used and the results of the PCA are presented in Appendix C.
Seasonal trends of temperature and dissolved oxygen were assessed from contour plots. Seasonal
plots of water quality parameters were generated using locally weighted scatter plot smoothing
(LOWESS). LOWESS is an exploratory technique that produces a best fit line to scatter plot data
Yadkin Project Water Quality Monitoring Study 14 Normandeau Associates
Water Quality
(Helsel and Hirsch, 1991). The shape of the trend line is determined by the data, no assumptions are
made about the form of the line. A smoothing factor is used to control the smoothness of the line.
For these plots, the three preceding and three succeeding months were weighted to determine the
slope of the line at each point. This produced trend lines that were based on season, relatively
resistant to extreme values and provided a good fit to the data without over-smoothing the line or
obscuring short-term trends.
Median values along with their 5 and 95 percentiles were tabulated for each parameter for each
tailrace. Seasonal LOWESS plots of monthly data were presented for parameters that were selected
based on the PCA-ordination.
Since differences between surface and bottom collections are likely to vary seasonally, monthly
surface and bottom medians were computed for each station and parameter. Reservoir stations were
grouped based on results of the PCA-ordination and monthly group medians were computed from the
monthly station medians. PCA-defined group surface and bottom medians were plotted for
parameters where large differences were observed.
Kendall's tau correlation coefficients were computed to examine whether relationships exist between
water quality and flow. Correlation coefficients were computed to examine whether relationships
between lake level and water quality exist in the reservoirs. Tailrace water quality was compared with
lake level in the upstream reservoir. Kendall's tau correlation is based on the ranking of the data and
is appropriate when the data includes values below a detection limit.
A Wilcoxon signed-rank test was used to test for differences between historical and current data.
Since historical data were limited, only comparable stations and months were used in the analysis.
Results of the Wilcoxon signed-rank test were only presented for High Rock Reservoir because there
was insufficient data in the other reservoirs. The Wilcoxon signed-rank test is a non-parametric test
that determines if significant differences exist between the distribution of ranks of two sets of samples
(Helsel and Hirsch 1991).
2.2 GENERAL TRENDS AMONG RESERVOIRS AND STATIONS
As the upper-most reservoir, High Rock receives its flow from the mainstem Yadkin River, the South
Yadkin River and several other sizeable tributaries. The principal flow source is the mainstem
Yadkin River, which drains a largely forested and agricultural region with some small towns and
cities. Proceeding downstream, water passes through Tuckertown, Narrows and Falls Reservoirs
before exiting the system. Tuckertown, Narrows and Falls reservoirs receive most of their water from
the preceding reservoir. Tailraces, or short sections of free-flowing river, exist below each dam, but
the water is quickly impounded as it enters the next reservoir. High Rock has a dendritic form, with
numerous large arms. Tuckertown and Falls Reservoirs have a linear shape and are essentially a
deepening of the original river channel. Narrows Reservoir has a somewhat dendritic shape, but is
best described as having two large basins. Reservoirs are essentially lake environments and physical
and biological processes in lakes differ from rivers and creeks (Wetzel 2001).
The quality of the surface water in the Yadkin APGI system is primarily affected by the passage of
water through the reservoirs and also by local factors like the influence of the Yadkin River and the
discharge from the four dams/powerhouses. The quality of bottom waters is not considered in this
section. Bottom waters are discussed in greater detail in Section 2.3.7. The factor that has the
Yadkin Project Water Quality Monitoring Study 15 Normandeau Associates
Water Quality
greatest influence on surface water quality is the upstream to downstream passage of water from the
upper end of High Rock Reservoir to Narrows Dam (Figure 2.2-1). The passage of water through the
system can take weeks, which allows sufficient time for physical and biological processes to modify
water quality. In addition to the effects of downstream passage, water quality is affected by local
environmental factors. The Yadkin River influences the two stations near its confluence with High
Rock Reservoir. Tailrace stations are similar to the dam stations of the preceding reservoir in their
nutrient and solids concentrations (the first principal component), but differ considerably in
temperature, pH, dissolved oxygen, nitrate and ammonia (the second principal component). The only
station in Falls Reservoir is closely allied to the tailrace stations, which suggests that in terms of water
quality, the entire Falls Reservoir (F2) could be considered similar to the tailrace of Narrows Dam
(FI). Relatively homogeneous conditions within Tuckertown and Narrows reservoirs are indicated by
the close grouping of stations (NI-N4, TI-T3). In contrast, High Rock Reservoir is an extremely
diverse waterbody. Large differences exist between the upper and lower mainstem stations and
among the arms (H1-H10). Tuckertown Reservoir is closely allied with the mainstem stations in the
lower portion of High Rock Reservoir (TI-T3), which suggests that water quality in Tuckertown
Reservoir is strongly influenced by conditions in High Rock Reservoir.
In general, the passage of water through the reservoirs results in improvement to the overall water
quality due to the reduction of suspended sediments, the increase in water clarity, and the gradual
reduction of algal biomass and nutrients. High Rock Reservoir is a very turbid reservoir with large
concentrations of suspended sediments and poor water clarity (Figure 2.2-2). The average Secchi
depth in High Rock Reservoir is about a half meter which means that light penetration and algal
productivity is probably limited to the top one meter. Being the furthest upstream reservoir, High
Rock is receiving a heavy load of solids from the mainstem river and tributaries that flow into it,
which has resulted in poor water clarity. Most of the suspended solids settle in High Rock Reservoir
and turbidity and suspended solids concentrations are much lower in Tuckertown Reservoir. There is
further reduction of suspended solids in Tuckertown and suspended solids are near the detection limit
in Narrows and Falls reservoirs. Secchi depth increases considerably in Narrows and Falls reservoirs
where the photic zone probably extends to a depth of over 3 meters (10 feet). The concentrations of
dissolved solids are generally not affected by the passage of water through the four reservoirs.
Sedimentation is discussed further in Section 3.6.
Heavy sediment loads are likely to carry greater concentrations of nutrients and other substances.
Both total phosphorus and total nitrogen concentrations are greatest in High Rock Reservoir and the
concentrations of phosphorus are at levels that can readily promote algal blooms and support a large
algal standing crop (Figure 2.2-3). The overall ratio of nitrogen to phosphorus is about 11,
(occasionally lower in the arms as discussed in Section 2.3. 1) which indicates that conditions favoring
cyanobacteria (bluegreen algae) may exist at times (HALMS 1990). Phosphorus concentrations
decrease in the downstream reservoirs, but concentrations remain at levels that are capable of
supporting considerable algal growth. Total nitrogen concentrations decrease only slightly as water
passes through the four reservoirs. The availability of nutrients in High Rock Reservoir has created a
large standing crop of algae as indicated by the large chlorophyll a concentrations, a surrogate
measure for algal biomass. Algal biomass decreases in the downstream reservoirs in a pattern that is
similar to the reduction in phosphorus concentrations which suggests that the magnitude of the algal
standing crop is largely determined by the phosphorus load in the reservoirs. Severe algal bloom
conditions, generally >30 µg/1, are typically not observed in Narrows and Falls reservoirs and the
nitrogen to phosphorus ratio favors eukaryotic algae (non-bluegreen). Large algal standing crop and a
Yadkin Project Water Quality Monitoring Study 16 Normandeau Associates
Water Quality
m

. 0
0
5

4
m v v ?
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CC CC C
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Tailraces
T1 N1
F1 F3
F2 Falls
H7 T2 Tuckertown
H1 T3 N4
H8
H9
H6
-2 0
N2 N3 Narrows
2 4
PC1
Upstream to Downstream
¦ Decreasing nutrients, solids and algal biomass
¦ Increasing water clarity
Figure 2.2-1. The relationships among reservoirs and stations based on PCA-ordination of log
(x+l) water quality parameters collected from surface samples, June 1999 to
December 2003.
shallow photic zone tend to produce near-saturated to supersaturated oxygen levels in the photic zone,
but as the micro-organisms settle into the underlying water, respiration and decomposition quickly
deplete oxygen concentrations, creating anoxic conditions. These anoxic conditions can influence
many other water quality parameters.
Based on the second principal component (Figure 2.2-1), the stations can be divided into three
groups. The upper High Rock Reservoir stations H1 and H3 form the first group. These stations are
located near the mouth of the Yadkin River in a relatively narrow and shallow stretch of the mainstem
of the reservoir. The four tailraces along with the Falls Reservoir station form the second group. The
remaining reservoir stations, which generally represent a lake-like environment, form the third group.
These groups were separated based on differences in physical properties, algal biomass and nitrate
and ammonia concentrations. Surface temperatures in the lake stations are slightly higher than at the
upper High Rock mainstem and tailrace stations (Figure 2.2-4). Due to the wide seasonal variation,
Yadkin Project Water Quality Monitoring Study 17 Normandeau Associates
0 150
z
0 125
J
N 100
n 70
A o
p CO
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? j
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High Rock Tuckertown Narrows Falls
C High Rock Tuckertown Narrows Falls High Rock Tuckertown Narrows Falls
n
0

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0 Figure 2.2-2. The median, 5, 25, 75, 95 percentiles and the mean of total dissolved solids, turbidity, total suspended solids and Secchi Depth in
rn High Rock, Tuckertown, Narrows and Falls Reservoirs.
(
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High Rock Tuckertown Narrows Falls High Rock Tuckertown Narrows Falls
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High Rock Tuckertown Narrows Falls High Rock Tuckertown Narrows Falls

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CID Figure 2.2-3. The median, 5, 25, 75, 95 percentiles and the mean of total nitrogen, total kjeldahl nitrogen, total phosphorus and chlorophyll a in
High Rock, Tuckertown, Narrows and Falls Reservoirs.
Water Quality
30
28
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Tailraces Lake
High Rock Stations
Mainstem
Ef?
Upper Tailraces Lake
High Rock Stations
Mainstem

Upper Tailraces Lake
High Rock Stations
Mainstem
Figure 2.2-4. Median, 5, 25, 75, and 95 percentiles and mean temperature, pH and dissolved
oxygen in the upper mainstem of High Rock Reservoir, tailraces and reservoir
stations.
Yadkin Project Water Quality Monitoring Study 20 Normandeau Associates
Water Quality
the differences appear small, but surface temperatures at the lake stations average about I°C warmer.
Differences in pH are also small, but surface pH is greater at the lake stations, where algal
productivity is likely to increase pH as carbon dioxide is utilized during photosynthesis. Surface
dissolved oxygen concentrations are considerably lower at the tailrace stations, with concentrations
less than 5 mg/l occurring in about 25% of the samples. Dam operations entrain both surface and
bottom water which are mixed during passage through the dam causing lower dissolved oxygen
concentrations in the tailrace if the bottom water of the upstream reservoir is oxygen depleted.
Surface dissolved oxygen concentrations are greatest at the lake stations, again a by-product of algal
productivity, but the range is greater than at the upper High Rock mainstem stations, and includes
some occurrences of concentrations below 5 mg/1. Algal populations in rivers and streams are
typically dominated by species that are attached to the bottom or other substrates. Species adapted to
open water, the phytoplankton, typically account for a small portion of stream algae. In contrast,
phytoplankton are the dominant algal species in lake environments (Wetzel 2001). The relatively low
chlorophyll a concentrations in the upper High Rock mainstem (Figure 2.2-5) indicate that
phytoplankton populations have not had sufficient time to develop and that this stretch may be more
like a river than a lake. The low chlorophyll a concentration in the tailraces is probably due to the
mixing of surface water and water below the photic zone with low algal biomass due to light
limitation. Nitrate concentrations are greater at the upper High Rock mainstem stations. Nitrate is
readily assimilated by phytoplankton and the greater concentrations observed at the upper High Rock
mainstem station can be attributed to the smaller algal population found there. Ammonia
concentrations are greatest in the tailraces. Although surface water concentrations of ammonia at the
lake stations are low, bottom water (Section 2.3.6) ammonia concentrations are seasonally greater.
The blending of surface and bottom water during passage through the powerhouse/dam results in
greater surface ammonia concentrations in the tailrace. Total Kjedahl nitrogen, a rough estimate of
organic nitrogen, is greater at the lake stations.
2.3 WATER QUALITY OF THE RESERVOIRS
2.3.1 High Rock Reservoir
The U.S. Army Corps of Engineer's Kerr-Scott Reservoir is the only impoundment upstream of High
Rock. However, it is located approximately 50 miles upstream and exerts no water quality influence
on High Rock Reservoir. The large basin covers most of the Piedmont region in north-central North
Carolina and drains a predominantly agricultural and forested region with rather highly erodible soils.
The dam forms a 15,180 acre reservoir, the largest of the four Alcoa reservoirs on the Yadkin River,
with a mean depth of 17 feet. The reservoir includes flooded portions of Swearing, Crane, Second,
Abbotts and Flat Swamp Creeks creating major arms. High Rock has a dendritic shape. Each major
arm receives runoff from at least one municipality, except for the Flat Swamp Creek Arm, which has
a relatively undeveloped watershed. Residence time of water entering High Rock Reservoir varies
considerably, ranging from 4 to 50 days (APGI 2002). It is the primary water storage body for the
Yadkin/Pee Dee System and seasonal drawdowns of 12 to 14 feet are typical.
High Rock Reservoir is a turbid lake with a shallow photic zone. Nutrient concentrations throughout
the reservoir are at levels that can support nuisance algae blooms and algal biomass is often at high
levels (>30 µg/1)(Table 2.3-1). Thermal stratification is absent, except for a slight warming of the top
few meters during the summer. Oxygen depletion below the photic zone occurs during the warmer
months. High Rock Reservoir is a very diverse waterbody. In general, the upper portion of the lake
Yadkin Project Water Quality Monitoring Study 21 Normandeau Associates
D
0
z
A
O
M
M
A
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Upper Tailraces Lake
High Rock Stations
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Upper Tailraces Lake
High Rock Stations
Mainstem
Upper Tailraces Lake Upper Tailraces Lake
High Rock Stations High Rock Stations
Mainstem Mainstem
n
0
ca'
CID
Figure 2.2-5. The median, 5, 25, 75 and 95 percentiles and the mean of chlorophyll a, nitrate, total kjeldahl nitrogen and ammonia in the upper
mainstem of High Rock Reservoir, tailraces and reservoir stations.

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Table 2.3-1. Median values of water quality parameters from June 1999 to December 2003 at each High Rock Reservoir station

igh Rock

Alkalinity
(mg/1) Biological
Oxygen
Demand
(mg/1)
Chlorophyll
a
(Ug/1)

Ammonia
(mg/1)

Nitrate
(mg/1)
Secchi
Depth
(m) Total
Kjeldahl
Nitrogen
(mg/1)
Total
Nitrogen
(mg/1) Total
Organic
Carbon
(mg/1)
Total
Phosphorus
(mg/1) Total
Dissolved
Solids
(mg/1)
Total
Solids
(mg/1) Total
Suspended
Solids
(mg/1)

Turbidity
(NTU)
Arms H2 31 3 27.20 0.06 0.14 0.38 0.84 1.03 4.90 0.14 90 114 27 47
H4 37 4 33.60 <0.05 0.12 0.35 0.94 1.13 6.20 0.18 100 131 28 45
H5 38 3 34.80 0.08 0.18 0.53 1.06 1.36 6.70 0.15 109 127 21 33
H6 33 3 26.80 0.10 0.21 0.64 0.88 1.19 5.15 0.11 94 107 15 23
H8 29 3 30.00 0.07 0.23 0.57 0.80 1.05 4.30 0.10 80 98 16 25
H9 25 2 21.80 0.06 0.25 0.82 0.65 0.87 4.10 0.06 75 85 10 13
Mainstem Hl 24 <2 4.00 0.06 0.81 0.47 0.59 1.40 3.20 0.21 84 108 24 38
H3 24 <2 9.65 0.09 0.76 0.39 0.63 1.45 3.25 0.18 81 94 12 19
H7 27 2 25.40 0.08 0.55 0.60 0.72 1.17 3.65 0.12 84 118 28 48
H10 27 2 20.80 0.10 0.44 0.80 0.66 1.12 3.80 0.09 79 98 15 26

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Water Quality
is more turbid and has greater nutrient concentrations than the lower regions. The major arms of the
reservoir typically have greater algal biomass than the mainstem and there are also differences among
the major arms (5). The Yadkin River has a strong influence on water quality in the upper portion of
the mainstem. Total solids, suspended solids, turbidity and the nutrients total phosphorus and total
nitrogen are greatest in the upper portion of the reservoir. This includes the upper two mainstem
stations and the arm stations of Swearing and Crane Creeks. Solids and nutrients are also greater in
the upper portion of Abbotts Creek Arm. These are stations that are most likely to be impacted by
surface runoff and river discharge. These are also shallow stations and wind-driven mixing of the
water column may be re-suspending bottom sediments.
When compared to the mainstem stations, arm stations typically have greater concentrations of
alkalinity, biological oxygen demand, chlorophyll a, total Kjeldahl nitrogen, total organic carbon and
total dissolved solids. These are all measures that are directly or indirectly affected by algal
productivity and suggest that productivity in the arms is very high. Average chlorophyll a
concentrations, the surrogate measure for algal biomass, for all arm stations is 29 µg/1, which is
almost double the average concentration in the mainstem of the reservoir. The large algal standing
crop in the arms contributes to larger concentrations of total organic carbon and total Kjeldahl
nitrogen, which is a rough estimate of organic nitrogen. Metabolic activity by algae and other
microorganisms increase total dissolved solids, biological oxygen demand and alkalinity. Nitrate
concentrations in the arms are much lower than in the mainstem. Nitrate is a form of nitrogen that is
readily available to algae and the lower nitrate concentrations in the arms are probably caused by the
assimilation of nitrate by algae. Stations in the arms are generally located near the mid-point, but the
extent to which water in the arms mix with mainstem waters, flushing rates and the effects of the
creek water on the arms is not known. The general trend suggests longer residence time in the arms,
which allows the algal community more time to exploit the high nutrient levels entering from
tributary streams.
There are some differences among the major arms of High Rock Reservoir. The Flat Swamp Creek
Arm, which has a relatively undeveloped watershed, has the best water quality observed in High Rock
Reservoir and is considerably different from the other arms. Flat Swamp Creek Arm has the greatest
water clarity, the lowest concentrations of dissolved and suspended solids, chlorophyll a and the
nutrients, total phosphorus and total nitrogen. Chlorophyll a concentrations are similar to
concentrations seen in the lower mainstem stations, and much lower than in the other arm stations.
Differences among the remaining arm stations are relatively small and comparisons of arms should be
made with some caution because of the lack of station replication in the arms.
The Swearing Creek and Crane Creek Arms are the most turbid arms in High Rock due to higher
concentrations of suspended solids and algae. The photic zone averages about 0.75 meters (2.5 feet)
in these two arms. The Crane Creek Arm has the greatest biological oxygen demand of all the arms.
Based on the single station, the Crane Creek Arm, due to its higher nutrient, algae and sediment
concentrations, probably has the worst water quality of all the arms, but Swearing Creek is only
slightly better. Th Abbotts Creek Arm is similar to the other arms, except that total nitrogen, and all
the forms of nitrogen which include ammonia, nitrate and organic nitrogen are slightly greater, but
difference is relatively small. Water clarity is better than in the Swearing and Crane Creek Arms, but
the photic zone is still shallow, averaging slightly over a meter. There are two stations in Abbotts
Creek Arm and the concentrations of suspended solids, nutrients and algal biomass are lower in the
downstream portion of the Arm. This is the same pattern that was observed in the upstream to
downstream passage of water through the reservoirs (previous section). The Second Creek Arm, with
Yadkin Project Water Quality Monitoring Study 24 Normandeau Associates
Water Quality
its more rural watershed has slightly better water quality than Swearing, Crane and Abbotts Creek
Arms. In this arm, the photic zone averages about 1.2 meters (4 feet). Nutrient concentrations and
algal the biomass are similar to the other arms, but suspended solids concentrations are slightly lower.
The nitrogen to phosphorus ratios are very low (<9) in Swearing, Crane and the upper portion of
Abbotts Creek arms, conditions that favor the growth of cyanobacteria (bluegreen algae) rather than
eukaryotic species (non-bluegreen algae).
The Yadkin River has a strong influence on the water quality of the two upper mainstem stations (HI
and 113). What makes these stations unique is the low chlorophyll a concentrations in the presence of
high nutrient levels, which is a condition that would be expected in a riverine environment where
most of the algae is attached to substrates and not present in the open water. The upper mainstem
stations of High Rock Reservoir also have high concentrations of suspended solids, which limit light
availability to algae. The water column at Station HI near the mouth of the Yadkin River (in the
vicinity of the Interstate 85 bridge) is usually well-mixed (Section 2.3.6) and slight current has been
reported there on a few occasions which suggests that Station HI is somewhat riverine. It is clear that
the Yadkin River is delivering very turbid water with high concentrations of nutrients, especially
nitrates and phosphorus, along with suspended solids and small amounts of algal biomass to High
Rock Reservoir. This is discussed further in Section 3.5. The water quality at Station H3 is very
similar to Station HI except that chlorophyll a concentrations are slightly greater. The effects of the
Yadkin River discharge extend at least six miles along the mainstem in the upper portion of High
Rock Lake.
Algal populations effectively begin to utilize the nutrient source provided by the Yadkin River
somewhere between the mainstem stations H3 and H7. There is a large increase in chlorophyll a and
a corresponding decrease of both total phosphorus and total nitrogen, mostly nitrate, in this stretch of
the impoundment. These reductions are likely due to sinking of suspended solids including algal
cells. Nutrients which are transported through the upper mainstem of the reservoir sustain a large
algal population in the lower portion of the reservoir. With a more stable water column and lake-like
conditions prevailing, algal populations in the lower mainstem portion of High Rock Reservoir have
sufficient time to more fully exploit the nutrient source. There is also likely to be some contribution
from the algal standing crop in the Swearing and Crane Creek Arms, which discharge into the
mainstem in this stretch.
Thermal stratification is typically absent near the dam in High Rock Reservoir (Station H10) except
for a slight warming of the surface few meters during the summer. Water temperatures from surface
to bottom follow an annual cycle with a seasonal low of about 6-8 °C in the winter and highs in
summer from 28-30°C (Figure 2.3-1). Weak temperature gradients of a few degrees occur during the
summer. The surface layer is only a few meters thick and surface temperatures are typically about 2
to 4 °C warmer than the bottom. The strongest thermal stratification observed at this station occurred
during the drought year of 2002.
Despite the lack of thermal stratification at this station, there is severe oxygen depletion, especially at
lower depths during the warmer months. Here, oxygen depletion is independent of thermal
stratification and simply extends from the reservoir bottom up to the lower limit of the photic zone.
In a typical year, lower bottom dissolved oxygen concentrations first appear around May and extend
through October or November (Figure 2.3-1). By July, low dissolved oxygen concentrations (<5
ppm) typically extend from the bottom to within a meter or two of the surface. Surface dissolved
oxygen concentrations below 5 ppm occurred at the surface in mid-summer of 1999 and 2001 and
Yadkin Project Water Quality Monitoring Study 25 Normandeau Associates
Water Quality
Water Temperature (deg C) at Station H10
200
195
190 h . n n nn nM*4VIOVµ" h n

C
2 185
N
W
180 V
175 ?I
170
61 61 61 61 O O O O N N N N M M M M 7
61 61 61 61 O O O O O O O O O O O O O O O O O
Z ? J H Z ? J H Z ? J H Z ? J H Z ? J H Z
a ? U ¢ a ? U ¢ a ? U ¢ a ? U ¢ a ? U
Q O Q O Q O Q O Q O
Month

200
195
190
E
c
2 185-
a)
W
180
175
170
61 61 61 61 O O O O N N N N M M M M 7
z 0) 6) 6) O O O O O O O O O O O O O O O O O
Z J H Z o- J H Z o- J H Z o- J H Z o- J ~ Z
a ? U ¢ a ? U ¢ a ? U ¢ a ? U ¢ a D U
Q O Q O Q O Q O Q O
Month
Figure 2.3-1. Temperature and dissolved oxygen profiles in High Rock Reservoir near the
dam from 1999 to 2003 (y axis scale of 170 to 200 meters is equivalent to 558
to 656 feet).
Yadkin Project Water Quality Monitoring Study 26 Normandeau Associates
Water Quality
briefly in 2002. Reduced flows and warmer water temperature during the extreme low lake levels of
2002 promoted intense algal production creating supersaturated conditions in the photic zone. In
2003, high flows and a full pool during the summer reduced the effects of oxygen depletion in High
Rock Reservoir. Dissolved oxygen concentrations were greater than 5 mg/l in the top four meters and
anoxic conditions were limited to the near bottom depths from July to September.
Spatially, dissolved oxygen characteristics vary in High Rock Reservoir. Low dissolved oxygen
concentrations are more likely to occur in the arms rather than the mainstem of High Rock Reservoir
(Table 2.3-2). The upper mainstem stations generally have adequate dissolved oxygen
concentrations, but low surface dissolved oxygen is a chronic problem in the Swearing Creek and
Crane Creek Arms of High Rock Reservoir. In the Crane Creek Arm, surface dissolved oxygen
concentrations were below 5 mg/l on 17 sampling dates (31%). Due to a large algal standing crop
and high levels of suspended solids, these two arms have a very shallow photic zone, averaging less
than a meter. Biological oxygen demand is also high in these arms, which suggests that these are
very productive areas and that oxygen can be consumed very quickly through microbial respiration.
The shallow water will also allow more frequent mixing of the photic zone with the oxygen depleted
water below resulting in an overall decrease in dissolved oxygen concentrations at the surface.
Conversely, extended periods of calm weather reduce mixing and result in the isolation of bottom
water and the development of anoxic conditions. The lower portion of High Rock where total depth
and the photic zone are deeper are less susceptible to the severe reduction of surface dissolved oxygen
due to the mixing of photic zone and bottom waters. The bottom water however remains isolated
from the surface and anoxia in the lower depths occurs more frequently. Dissolved oxygen profiles
for Stations HI to H9 are presented in Appendix D.
Table 2.3-2. Dissolved oxygen characteristics of stations in High Rock Reservoir.
Number of sampling dates where:'

Station Anoxia (<1 mg/1) in
deeper water Low DO (<5 mg/1) in
surface 2 meters
Arms
H2 4 17
H4 3 12
H5 10 5
H6 18 3
H8 9 7
H9 10 2
Mainstem
H1 0 0
H3 0 2
H7 3 2
H10 16 5
'Total number of sampling dates varies from 53 to 55.
Yadkin Project Water Quality Monitoring Study 27 Normandeau Associates
Water Quality
2.3.2 Tuckertown
Tuckertown Reservoir lies immediately downstream of the High Rock Dam tailrace. It is a relatively
small reservoir of 2560 acres, with a linear basin shape and two small arms. Average residence time
in the reservoir is estimated at about 22 hours. Average depth is 5 meters (16 feet) with a maximum
depth of 17 meters (55 feet) near the Tuckertown Dam. The shoreline is generally undeveloped and
Tuckertown Reservoir receives almost all of its flow from High Rock Reservoir.
The water quality in Tuckertown Reservoir is similar to the water quality in the lower portion of High
Rock Reservoir (Section 2.3.1). The short residence time in Tuckertown Reservoir does not allow
sufficient time for physical and biological processes to change water quality. In general it is a
relatively turbid reservoir with a shallow photic zone (Table 2.3-3). Nutrient concentrations are still
at levels that can promote nuisance algae blooms and algal biomass remains at high levels.
Chlorophyll a concentrations in the reservoir are slightly greater than those observed in the High
Rock Dam tailrace (Section 2.4) indicating that some productivity is occurring in the reservoir.
Although the suspended solids concentrations are much lower than High Rock Reservoir, they are
still greater than levels typically seen in lakes and reservoirs (Wetzel 2001).
As in High Rock, weak thermal stratification of the water column occurs during the summer months
in Tuckertown Reservoir. The difference between surface and bottom temperatures, a few degrees, is
generally limited to the top five meters (Figure 2.3-2). Pool elevation was maintained at a near
constant level during the drought year of 2002 and high flow year of 2003 and vertical thermal
gradients were similar in both years.
Dissolved oxygen depletion in deeper water typically extends from May through October or
November, but anoxic conditions are usually limited to the summer months and to depths below five
meters. Dissolved oxygen in the upper five meters of the water column varies considerably among
the sampling years. Low dissolved oxygen concentrations (<5 mg/1) at the surface were observed
from July to September 1999, August to October 2000, July to August 2001 and briefly in October
2002. In 2003, low dissolved oxygen concentrations were not observed in the upper five meters and
bottom dissolved oxygen levels remained above 3 mg/l throughout the year. During the low flow
period of 2002 (when the pool elevation of High Rock Reservoir was extremely low), dissolved
oxygen concentrations in the top four meters of Tuckertown Reservoir were greater than 7 mg/1, but
there was rapid depletion to anoxic conditions below four meters. Both surface and bottom dissolved
oxygen concentrations were higher than typical in 2003, the high flow year. The effects of
hydroelectric facility operations on dissolved oxygen are discussed in Section 3.4.
Lick Creek and Upper Tuckertown Reservoir
Additional sampling began in the Lick Creek Arm and upper mainstem of the Tuckertown Reservoir
in July 2003 in response to comments from the North Carolina Division of Water Quality. The
sampling consisted of a series of temperature and dissolved oxygen profiles in the mainstem below
the High Rock Dam tailrace and two additional stations in the Lick Creek Arm. Temperature and
dissolved oxygen profiles along with water sampling for nutrients and solids was conducted at an
additional station in the free-flowing portion of Lick Creek upstream of the confluence with
Tuckertown Reservoir. The sampling plan was designed to determine if Lick Creek influenced water
quality in Tuckertown Reservoir.
Yadkin Project Water Quality Monitoring Study 28 Normandeau Associates
N
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Table 2.3-3. Median values of water quality parameters from June 1999 to December 2003 at each station in Tuckertown, Narrows
and Falss Reservoirs

Alkalinity
(mg/1) Biological
Oxygen
Demand
(mg/1)
Chlorophyll
a
(99/1)

Ammonia
(mg/1)

Nitrate
(mg/1)
Secchi
Depth
(m) Total
Kjeldahl
Nitrogen
(mg/1)
Total
Nitrogen
(mg/1) Total
Organic
Carbon
(mg/1)
Total
Phosphorus
(mg/1) Total
Dissolved
Solids
(mg/1)
Total
Solids
(mg/1) Total
Suspended
Solids
(mg/1)

Turbidity
(NTU)
Tuckertown T2 25 2 17.2 0.08 0.47 0.73 0.68 1.15 3.75 0.08 82 96 11.05 17.05
T3 26 2 16.4 0.10 0.45 0.90 0.68 1.10 3.70 0.08 80 92 9.00 15.10
Narrows N2 25 <2 14.0 0.06 0.42 1.18 0.60 0.88 3.60 0.06 77 80 5.60 7.45
N3 25 <2 6.8 0.05 0.43 1.68 0.57 0.87 3.50 0.04 70 75 <5 4.85
N4 27 <2 8.4 0.08 0.42 1.43 0.61 1.13 3.65 0.05 76 78 <5 5.00
Falls F2 25 <2 5.6 0.06 0.46 1.60 0.54 0.76 3.45 0.04 74 74 <5 4.50

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Water Quality
180
175
170
E
C
165
N
W
160
155
150
Water Temperature (deg C) at Station T3
V
6) 6) 6) 6) O O O O N N N N M M M M 7
6) 6) 6) 6) O O O O O O O O O O O O O O O O O
Z 0? J H Z 0? J H Z 0? J H Z 0? J H Z 0? J H Z
CL U ¢ a U ¢ o- U ¢ a U ¢ a U
Q - O - Q O - Q - O - Q O - Q O
Month
180
175
170
E
C
165
N
W
160
155
150
Dissolved Oxygen (mg/L) at Station T3
Illr<
6) 6) 6) 6) O O O O N N N N M M M M 7
6) 6) 6) 6) O O O O O O O O O O O O O O O O O
Z 0? J H Z 0? J H Z 0? J H Z 0? J H Z 0? J H Z
CL U ¢ o- U ¢ o- U ¢ o- U ¢ a D U
Q - O - Q O - Q - O - Q O - Q - O
Month
Figure 2.3-2. Temperature and dissolved oxygen profiles in Tuckertown Reservoir near the
dam from 1999 to 2003 (y axis scale of 150 to 180 meters is equivalent to 492
to 591 feet).
Yadkin Project Water Quality Monitoring Study 30 Normandeau Associates
Water Quality
The profiles in the mainstem below the High Rock Dam tailrace and in the Lick Creek Arm were
measured in a relatively brief period (about 10 minutes apart) which almost provides a snapshot of the
area. This sampling was usually conducted in the late afternoon which is probably near the daily
maximum for both temperature and dissolved oxygen. Thermal stratification was not observed in the
mainstem below the High Rock Dam tailrace on any sampling date (Table 2.3-4). In contrast, intense
warming of the surface water occurred in the Lick Creek Arm. The difference between the surface
and the bottom ( at 2 meters) was as great as 7.3°C, but was more typically in the 2-3°C range.
Thermal stratification occurred every month except for October and December. Temperatures in the
Lick Creek Arm and the mainstem were generally similar on each sampling date.
Dissolved oxygen concentrations below the High Rock Dam tailrace were greater than 5 mg/l in
every month, except for August and a few bottom readings in July (Table 2.3-5). In August,
dissolved oxygen concentrations ranged from 3.79 to 4.73 mg/1. Oxygen depletion in the bottom
waters was generally limited to a few tenths of a mg/1. In the Lick Creek Arm, surface dissolved
oxygen concentrations were always greater than 5 mg/1. Low dissolved oxygen (<5 mg/1) occurred
only near the bottom at both stations in July and at the upstream station in August. Dissolved oxygen
concentrations varied widely in the Lick Creek Arm. Extremely high values at the surface in July
suggest intense algal productivity and concentrations at supersaturation levels. The temperature and
dissolved oxygen profiles suggest that the Lick Creek Arm does not mix to any great extent with the
mainstem and has very little effect on the mainstem.
Lick Creek was also sampled for nutrients, solids and other water quality parameters in the free-
flowing section upstream of its confluence with Tuckertown Reservoir (Table 2.3-6). Chlorophyll a
concentrations were low despite high nutrient levels as is expected in a stream environment. Most of
the nitrogen was organic, although nitrates contributed a large percentage as well. The supersaturated
levels of dissolved oxygen in the Lick Creek Arm indicates that the nutrients being supplied by Lick
Creek are being exploited as the creek water enters the reservoir. Concentrations of total organic
carbon were rather high in Lick Creek. Low algal biomass and low biological oxygen demand
suggest that a significant portion of the total organic carbon may be detrital. Turbidity was relatively
low for a stream environment. Suspended solids were at levels below the detection limit except for
July. Streams are influenced by recent storm events that may produce runoff. The monthly variation
in water quality in Lick Creek was considerable and probably related to storm events around the
sampling dates. The main differences between Lick Creek water quality and the receiving waterbody,
Tuckertown Reservoir, is that Lick Creek has higher alkalinity, lower algal biomass and greater
concentrations of total phosphorus, total organic carbon and dissolved solids. Lick Creek is small and
although the concentration of total phosphorus may be double in the creek, the load to Tuckertown
Reservoir is probably negligible.
2.3.3 Narrows
Narrows Reservoir is the second largest reservoir in the project area covering 5355 acres at full pool.
The reservoir has a somewhat dendritic pattern and can be divided into two large basins. Narrows
Reservoir receives most of its flow from Tuckertown Reservoir. The mainstem of the Yadkin River
forms one of the major basins, the other basin created by the Gladys Fork Arm. The shoreline is
mostly residential with some undeveloped areas and the lake is popular as a recreation area. Average
residence time in the reservoir is estimated at 2 days. Narrows Reservoir is the deepest of the
reservoirs with maximum depth near the dam at 53 meters (175 feet). Average depth is 14 meters (45
feet), which is more than double that of the other three reservoirs.
Yadkin Project Water Quality Monitoring Study 31 Normandeau Associates
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Table 2.3-4. Temperature profiles in Lick Creek, Lick Creek Arm and upper Tuckertown Reservoir from July to December 2003.
Lick Creek Lick Creek Arm Upper Tuckertown Reservoir (distance from T1 in miles)
T4 TP8 TP7 TP1 TP2 TP3 TP4 TP5 TP6 TP9
Depth Upstream Near Mouth 0.19 0.27 0.44 0.82 1.32 1.74 1.91
Date m It °C °C °C °C °C °C °C °C °C °C
07/15/03 0 0 25.4 31.46 28.71 25.9 25.91 25.92 25.98 25.97 25.96 25.88
1 3.3 24.9 26.77 25.9 25.88 25.91 25.98 25.95 25.95 25.86
2 6.6 24.18 25.59 25.89 25.98 25.95 25.95 25.88
3 9.8 25.95 25.96 25.89
4 13.1 25.89
08/19/03 0 24.51 25.99 26.87 25.67 25.72 25.86 25.93 28.81 26.03 26.27
1 3.3 24.27 26.73 25.66 25.72 25.83 25.74 25.75 25.83 25.93
2 6.6 24.16 25.26 25.67 25.67 25.69 25.73 25.83
3 9.8 25.69 25.76
4 13.1 25.73
09/22/03 0 0 20.98 22.57 22.81 22.08 22.08 22.11 22.14 22.15 22.23 22.2
1 3.3 20.36 22.46 22.07 22.09 22.11 22.14 22.15 22.21 22.2
2 6.6 20.13 20.44 22.13 22.15 22.22 22.2
3 9.8 22.15 22.21 22.2
4 13.1 22.21 22.2
10/27/03 0 0 15.62 15.46 16.31 16.98 17.01 16.92 16.93 16.85 16.74 16.69
1 3.3 15.47 16.41 17.01 17.02 16.93 16.93 16.85 16.74 16.68
2 6.6 15.47 16.33 17.01 16.93 16.85 16.74 16.69
3 9.8 16.73 16.69
4 13.1 16.69
11/18/03 0 0 14.14 14.06 15.17 13.7 13.7 13.7 13.72 13.67 13.81 13.81
1 3.3 12.77 14.64 13.69 13.7 13.7 13.72 13.67 13.79 13.8
2 6.6 12.67 13.76 13.68 13.72 13.67 13.79 13.81
3 9.8 13.79 13.81
4 13.1 13.79
12/16/03 0 0 6.13 5.38 5.87 6.53 6.53 6.52 6.55 6.58 6.63 6.66
1 3.3 5.24 5.73 6.53 6.53 6.52 6.54 6.57 6.63 6.65
2 6.6 5.22 5.61 6.54 6.57 6.62 6.65
3 9.8 6.57 6.62 6.65
4 13.1 6.63 6.65

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Table 2.3-5. Dissolved oxygen profiles in Lick Creek, Lick Creek Arm and upper Tuckertown Reservoir from July to December
2003.
Lick Creek Lick Creek Arm Upper Tuckertown Reservoir (distance from T1 in miles
T4 TP8 TP7 TP1 TP2 TP3 TP4 TP5 TP6 TP9
Depth Upstream Near mouth 0.19 0.27 0.44 0.82 1.32 1.74 1.91
Date m It mg/1 mg/1 mg/l mg/1 mg/l mg/l mg/l mg/l mg/l mg/l
07/15/03 0 0 6.75 12.57 8.48 5.41 5.48 5.36 5.99 5.29 5.3 5.25
1 3.3 7.13 6.48 5.23 5.18 5.27 5.38 5.13 4.97 5
2 6.6 4.89 2.87 5.2 5.3 5.11 4.94 4.91
3 9.8 5.1 4.91 4.89
4 13.1 4.87
08/19/03 0 6.72 5.51 8.02 4.73 4.49 4.49 4.59 4.29 4.47 4.66
1 3.3 5.12 8.27 4.33 4.31 4.09 4.18 4.09 4.28 4.32
2 6.6 4.93 6.09 4.32 3.92 3.93 4.01 4.1
3 9.8 3.86 3.92
4 13.1 3.79
09/22/03 0 0 7.43 7.15 7.67 6.28 6.09 6.25 6.24 6.21 6.4 6.49
1 3.3 6.93 6.88 6.04 5.99 6.06 6.06 6.05 6.21 6.33
2 6.6 6.46 5.76 6.02 6.01 6.14 6.26
3 9.8 6 6.12 6.23
4 13.1 6.11 6.21
10/27/03 0 0 6.52 6.44 6.98 8.43 8.12 8 7.93 8.44 8.63 8.19
1 3.3 6.01 7.06 8.21 8.04 7.94 7.92 8.45 8.58 8.06
2 6.6 5.89 6.91 8.12 7.94 8.47 8.55 8
3 9.8 8.55 7.94
4 13.1 7.92
11/18/03 0 0 8.07 7 9.2 8.93 8.78 8.91 8.9 8.98 8.93 9.3
1 3.3 6.51 8.69 8.83 8.77 8.81 8.8 8.86 8.83 8.93
2 6.6 5.99 7.78 8.8 8.76 8.82 7.77 8.8
3 9.8 8.74 8.77
4 13.1 8.72
12/16/03 0 0 11.34 11.47 11.01 10.95 10.95 10.94 11.04 11.03 10.98 11.28
1 3.3 11.17 10.67 10.82 10.82 10.83 10.89 10.92 10.9 11.03
2 6.6 11.04 10.54 10.82 10.88 10.84 10.95
3 9.8 10.83 10.82 10.9
4 13.1 10.8 10.88

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Table 2.3-6. Monthly water quality in Lick Creek and the median from Lick Creek and Tuckertown Reservoir from July to
December 2003.
Date Median

Parameter
7/15/2003
8/19/2003
9/22/2003
10/27/2003
11/18/2003
12/16/2003 Lick
Creek Tuckertown
Reservoir
Alkalinity (mg/1) 33 37 24 39 37 12 35 21
Chlorophyll a (gg/1) 0.8 2.0 2.8 2.0 3.2 1.6 2.0 8.8
Total phosphorus (mg/1) 0.21 0.11 0.14 0.28 0.09 0.05 0.13 0.06
Turbidity (NTU) 13 16 11 11 8 27 12 16
Nitrate (mg/1) 0.80 0.45 0.57 0.19 0.17 0.60 0.51 0.47
Ammonia (mg/1) <0.05 0.07 <0.05 <0.05 <0.05 <0.05 <0.05 0.06
Total Kjeldahl nitrogen (mg/1) 0.95 0.74 1.71 <0.5 0.68 <0.5 0.71 0.68
Total nitrogen (mg/1) 1.75 1.19 2.28 <0.5 0.85 0.60 1.02 1.13
Total organic carbon (mg/1) 6.4 9.2 6.1 6.3 4.6 6.8 6.35 3.25
Biological oxygen demand (mg/1) 3 <2 <2 <2 <2 <2 <2 <2
Chemical oxygen demand (mg/1) <20 <20 36 <20 29 <20 <20 <20
Total solids (mg/1) 94 110 84 118 90 82 92 66
Total dissolved solids (mg/1) 38 58 88 118 100 88 88 67
Total suspended solids (mg/1) 33 <5 <5 <5 <5 <5 <5 7

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Table 2.3-7. The number of sampling dates when concentrations of nitrite, chemical oxygen demand and toxic substances were above
the detection limit in either the surface or bottom samples at each station from June 1999 to December 2003.
Parameter Nitritea COD' Cadmium Cyanide Copper Lead Mercury`
(detection limit) (<0.1 mg/1) (<20 mg/1) (<0.5,ug/1) (<0.005 mg/1) (<10 µg/1) (<2 µg/1) (<0.2 Acg/1)
Reservoir Station
High Rock Arms H2 24 2 3 4 28 4
H4 1 26 1 6 12 35 2
H5 1 27 2 5 7 28 1
H6 16 1 3 7 22 2
H8 17 1 3 3 20 1
H9 8 2 1 4 8
High Rock Mainstem H1 10 2 1 7 27 6
H3 10 1 3 6 28 1
H7 2 9 3 6 20
H10 1 9 2 2 6 17 1
Tuckertown T1 9 2 2 10
T2 6 1 2 6 15
T3 7 1 5 10
Narrows N1 1 3 2 4 4
N2 8 2 1 6
N3 2 1 1 5
N4 12 2 7 23
Falls F1 1 5 1 4 1
F2 2 1 7 3 5 1
F3 1 1 7 1
'Nitrite concentrations above the detection limit were observed on four dates: 8123199, 9/7/99, 8/22/00, 8/21/02
b COD = Chemical Oxygen Demand
'Only 8 of the 24 observations of mercury concentrations above the detection limit in High Rock Reservoir occurred on 12/20/00

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Water Quality
Narrows has greater water clarity and lower concentrations of suspended solids, nutrients and algal
biomass than the two upstream reservoirs (Table 2.3-3) and better surface dissolved oxygen
conditions than Falls Reservoir which lies downstream (Section 2.3.4). The surface waters are less
turbid than the upstream reservoirs, but the photic zone is still relatively shallow, with averages
ranging from about 2.4 to 3.4 meters. Average suspended solids concentrations at Narrows are near
the detection limit. Nutrient concentrations are lower than in High Rock and Tuckertown Reservoirs,
but they are still at levels that can produce nuisance algal blooms, althoughsuch blooms are likely to
occur at a lower frequency in Narrows than in the upper reservoirs. Narrows, with its deeper water, is
the only reservoir where a true hypolimnion develops (>4°C difference between surface and bottom
temperatures).
Water quality conditions across the reservoir are homogeneous and differences among the stations are
very small. Slightly greater chlorophyll a and suspended solids concentrations occur at the mainstem
station that is closest to the Tuckertown Dam tailrace. The Gladys Fork Arm of the reservoir has
slightly lower algal biomass, suspended and dissolved solids and total phosphorus than the two
stations along the mainstem, but the differences are very small. Total nitrogen concentrations are
greatest near the dam.
A strong and persistent thermocline develops near the dam in Narrows Reservoir. Thermal
stratification typically begins to develop in May and persists, in some years, into December (Figure
2.3-3). By mid-summer, a well developed epilimnion (warm upper layer) extends from the surface to
a depth of about 15 to 20 meters and a well defined metalimnion (transitional layer) separates the
epilimnion from the hypolimnion (cool lower layer). Epilimnetic waters reach a maximum of about
30°C in summer. Hypolimnetic waters average 8 to 10°C throughout the spring summer and fall.
The upper limit of the hypolimnion is typically at about a depth of 27 meters or 88.5 feet (pool
elevation 128 m or 420 feet). Throughout the fall, the metalimnion thins as the epilimnion cools and
deepens. Turnover occurs in late summer or early fall.
Dissolved oxygen concentrations in the upper four or five meters (13-16 feet) are usually greater than
5 mg/1. Below five meters, low dissolved oxygen concentrations (<5 mg/1) persist from June through
September. Oxygen depletion is independent of thermal stratification, occurring in the deeper
portions of the epilimnion as well as the metalimnion and hypolimnion. There is a step-wise retreat
of the low dissolved oxygen water in the fall. This is probably due to periodic storm events that cause
mixing of the epilimnion along with the gradual destruction of the metalimnion. Complete mixing of
the reservoir usually occurs in December or January and dissolved oxygen concentrations are similar
throughout the water column until stratification returns in late spring.
There are slight differences among years in development of the thermocline. The epilimnion was a
little shallower in 2001 and 2002. The epilimnion developed to greater depth earlier during the high
flow year of 2003. Dissolved oxygen concentrations were much greater during 2003 and anoxia was
not observed in the upper 20 meters (66 feet) of water. A persistent layer of oxygenated water was
wedged between two anoxic layers at a reservoir elevation of 120 to 130 meters (80-110 feet below
normal full pool). This phenomenon was observed to a lesser extent in 1999 and 2000. This
corresponds to the upper portion of the hypolimnion. This is usually caused by a faster rate of oxygen
depletion in the metalimnion. Particles tend to concentrate in the metalimnion as they encounter a
density gradient caused by the temperature change. With a more concentrated source of nutrition and
slightly warmer temperature to increase metabolism, decomposers tend to deplete the dissolved
oxygen in the metalimnion faster than in the underlying hypolimnion. This phenomenon occurred in
Yadkin Project Water Quality Monitoring Study 36 Normandeau Associates
Water Quality
Water Temperature (deg C) at Station N4
1E
1E
1E
14
14
E 13
c
2) 12
N 12
W
12
11
11
1C
1C
Dissolved Oxygen (mg/L) at Station N4
1E
1E
1E
14
14
E 12
c
2) 12
N 12
W
12
11
11
1C
1C
Figure 2.3-3 Temperature and dissolved oxygen profiles in Narrows Reservoir near the dam
from 1999 to 2003 (y axis scale of 100 to 160 meters is equivalent to 328 to
525 feet).
Yadkin Project Water Quality Monitoring Study 37 Normandeau Associates
z 0? o o
z ? J H Z ? J H Z 0? J H Z ? J H Z 0? J H Z
a U ¢ o- U ¢ o- U ¢ o- U ¢ a U
Q O Q O Q O Q O Q O
Month
M M M M o 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Z 0? J H Z 0 J H Z 0? J H Z 0 J H Z 0? J H Z
a U ¢ a U ¢ o- U ¢ o- U ¢ a D U
Q O Q O Q O Q O Q O
Month
Water Quality
years where the epilimnion was deeper and developed earlier, thereby creating a deeper, but more
pronounced metalimnion.
The station near the Narrows Dam is unique because it is the only station in any of the reservoirs
where a hypolimnion develops. The other two stations in Narrows Reservoir are shallower and the
warming of the surface waters extends to the bottom (Appendix E). Some thermal stratification is
observed at the other two stations, with differences between the surface and bottom being as great 10
or 12°C in the late spring and early summer. By late summer, the epilimnion extends to near the
bottom and differencesbetween surface and bottom temperature decreases to about 4 to 6°C. Oxygen
depletion occurs during the period of thermal stratification at depths below 3 or 4 meters (10-13 feet).
Complete turnover of the water column occurs earlier at Stations N2 and N3 when compared to the
dam station (N4). Turnover usually occurs in late September or early October, at which point,
oxygen levels throughout the water column exceed 5 mg/1.
2.3.4 Falls
Falls Reservoir is the lower-most of the Alcoa reservoirs on the Yadkin River. It has no tributaries of
any size and receives almost all of its water from Narrows Reservoir. It is a small reservoir of 204
acres with a predominantly forested shoreline. Falls Reservoir is linear in shape, amounting to little
more than a deepening and slight widening of the original river channel. The average residence time
is estimated at 2 hours.
Falls Reservoir has the lowest concentrations of solids, nutrients and algal biomass of all the
reservoirs. The levels are generally similar to the concentrations observed in Narrows Reservoir near
the dam (Table 2.3-3). Due to the short residence time, limnetic processes do not have sufficient time
to alter the water quality. Nutrient concentrations are still at levels that could promote algal blooms.
However, algal biomass is low because Falls Reservoir receives as a portion of the discharge, deep
epilimnetic water that is assumed to have low algal biomass and the residence time in the reservoir is
not sufficient for algal populations to develop. Average Secchi depth is 1.6 meters indicating a photic
zone of about 3 meters. Suspended solids concentrations are below detection level.
The PCA-ordination (Section 2.2; Figure 2.2-1) groups the Falls Reservoir station (F2) in close
proximity to the Narrows and Falls tailraces. In a sense, the entire Falls Reservoir can be considered
as the tailrace of Narrows Dam. The mid-water discharge from Narrows Reservoir includes cooler
anoxic water that lowers temperature, pH and dissolved oxygen levels throughout Falls Reservoir.
Thermal stratification does not occur in Falls Reservoir (Figure 2.3-4). Temperatures range from
about 8 to 28 °C. Dissolved oxygen concentrations observed at the surface range from 3 to I I mg/1.
In a typical year, low dissolved oxygen concentrations extend from the bottom to within a meter or
two of the surface from June to October, but anoxic conditions have not been observed. Low
dissolved oxygen water (<5 mg/1) is occasionally observed at the surface. Low dissolved oxygen
concentrations did not occur during the high flow year of 2003.
2.3.5 Toxic Substances, Chemical Oxygen Demand and Nitrite
Several parameters are treated separately because they typically occur at concentrations that are
below the detection level of the test method. This includes all five of the toxic substances that were
tested along with chemical oxygen demand and nitrite-nitrogen. These parameters are evaluated by
the frequency of detectable levels at each station by sampling date (Table 2.3.7). The overall median
Yadkin Project Water Quality Monitoring Study 38 Normandeau Associates
Water Quality
Water Temperature (deg C) at Station F2
110
105-
• ,-.1?MM \ / m I I I III
100-
C
95
cc
N
W
90
85
80
61 61 61 61 O O O O N N N N M M M M 7
z 0 ) 6) 6) O O O O O O O O O O O O O O O O O
Z ? J H Z 12? J H Z 12? J H Z 12? J H Z 12? J H Z
CL U ¢ o- U ¢ o- U ¢ o- U ¢ a D U
Q - 0 - Q - O - Q - O - Q - O - Q - O
Month
Dissolved Oxygen (mg/L) at Station F2
110
105
100 Iti?VYr n v s, a IIII ??
0 95 ? ? I ? u 1sJ V ?
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N
W
90
85
80
61 61 61 61 O O O O N N N N M M M M 7
z 0 ) 6) 6) O O O O O O O O O O O O O O O O O
Z ? J H Z 12? J H Z 12? J H Z 12? J H Z 12? J H Z
a U ¢ o- U ¢ o- U ¢ o- U ¢ a D U
Month
Figure 2.3-4. Temperature and dissolved oxygen profiles in Falls Reservoir near the dam
from 1999 to 2003 (y axis scale of 80 to 100 meters is equivalent to 262 to 361
feet).
Yadkin Project Water Quality Monitoring Study 39 Normandeau Associates
Water Quality
values of all seven of these test parameters was below the detection level, although not necessarily at
every station.
Nitrite-nitrogen was rarely observed at concentrations above the detection level. Detectable levels
were observed in the Crane Creek Arm (114) and upper portion of Abbotts Creek Arm (115) and the
two lower mainstem stations of High Rock Reservoir. Nitrite concentrations were also detected in the
tailraces of Tuckertown and Narrows Dams. It was detected on only four sampling dates, all in late
August or early September. In natural waters, nitrite concentrations are usually determined by an
equilibrium with nitrate where nitrite concentrations are typically about 10 percent of the nitrate
levels and nitrate concentrations in the project area were usually below I mg/1. Detectable levels of
chemical oxygen demand (COD) were observed at every station. COD at concentrations above the
detection limit occurred most frequently in the arms of High Rock Reservoir, with the exception of
Flat Swamp Creek. In the upper arms of High Rock Reservoir, which is an area prone to low surface
dissolved oxygen concentrations, detectable levels of COD occurred on about half of the collection
dates and levels were often high. COD levels were also greater near the Narrows Dam (Station N4).
These occurrences were mostly in the hypolimnion at Station N4 where a persistent hypolimnion
creates anoxic conditions for most of the year allowing the accumulation of oxidizable compounds.
There is a general upstream to downstream decrease in the occurrence of detectable levels of COD
through the system of reservoirs. The less frequent occurrence of detectable levels of COD is similar
to the reduction of suspended solids and algal biomass as water passes through the system of
reservoirs.
Cadmium concentrations were rarely above the detection limit. Most observations were in High Rock
Reservoir, but detectable levels were also observed at stations in Tuckertown and Falls Reservoirs.
Cadmium was not detected in any of the tailraces or in Narrows Reservoir. The greater occurrence of
cadmium at detectable levels in High Rock Reservoir and its relative scarcity in the other reservoirs
suggests that High Rock is trapping most of the cadmium in its sediments.
Cyanide was detected at every station. However, differences among stations were small in terms of
the frequency of detectable cyanide. Cyanide was most likely to be detected in Crane Creek and the
upper portion of Abbotts Creek Arms in High Rock Reservoir, the stations in Tuckertown and Falls
Reservoirs and in the tailrace below Tuckertown Dam. Detectable levels of cyanide occurred most
frequently in the arms of High Rock Reservoir where large standing crops of algae are found.
Although algae is not likely to generate cyanide, the large standing crops and high dissolved oxygen
concentrations indicate that these are very productive areas and that the cyanide may be generated by
other micro-organisms in these areas. There seems to be an unusually high frequency of detectable
cyanide concentration in Falls Reservoir.
Copper was most likely to occur at detectable levels in High Rock and Tuckertown Reservoirs.
Occurrences downstream from the Tuckertown tailrace were sporadic. The occurrences of copper in
High Rock and Tuckertown Reservoirs was relatively evenly spread among the stations, except for
the Crane Creek Arm (114) where 12 of 54 collection dates (22%) had detectable levels of copper.
The overall trend suggests a slight decrease in copper concentrations as water moves through the four
reservoirs.
Lead was the most commonly occurring toxic substance that was tested. The greatest frequency and
highest concentrations were observed in the upper portions of High Rock Reservoir. Both the
mainstem stations and the arm stations in the upper portion of High Rock Reservoir had detectable
levels of lead on over half of the sampling dates. Lead levels were low in the Flat Swamp Creek Arm
Yadkin Project Water Quality Monitoring Study 40 Normandeau Associates
Water Quality
of High Rock Reservoir, however. The frequency of detectable levels of lead decreases in the
downstream reservoirs and is lowest in Narrows and Falls.
Mercury most frequently occurred at detectable levels in High Rock Reservoir and in the
hypolimnion of Narrows Reservoir. In High Rock Reservoir, mercury was most likely to be observed
near the mouth of the Yadkin River (6 of 55 samples over 4.5 years) or in Swearing Creek Arm (4 of
55 samples) in the upper portion of the reservoir. Mercury was observed above the detection limit in
Abbotts Creek Arm (3 of 55 samples), the recipient of historical mercury discharges from the
Duracell battery plant in Lexington. The occurrence of mercury was generally sporadic in High Rock
Reservoir, except for December 20, 2000 when detectable levels of mercury occurred at 7 of the 10
stations. Mercury was not detected in Tuckertown Reservoir and most of Narrows Reservoir, which
suggests that mercury entering High Rock Reservoir from the Yadkin River and Swearing Creek is
retained within High Rock Reservoir. Detectable levels of mercury occurred on almost half of the
sampling dates at Station N4 near the Dam in Narrows Reservoir, the only station with a
hypolimnion. The anoxic hypolimnion persists for most of the year during which time the
hypolimnion is isolated from the surface waters allowing the accumulation of dissolved mercury
compounds. The hypolimnion of Narrows Reservoir is probably a source of dissolved forms of
mercury. Detectable levels of mercury occurred on one sampling date in each of the Narrows and
Falls tailraces and Falls Reservoir. The mercury in the hypolimnion of Narrows Reservoir is either
being retained in this reservoir and converted back to insoluble forms of mercury during turnover, or
it is being diluted to levels below the detection limit as hypolimnetic water is mixed with surface
water in the passage through Narrows Dam.
The metals, lead, copper, mercury and cadmium were more likely to occur at detectable levels in
High Rock Reservoir, particularly the upper portions. High Rock is the reservoir that is most affected
by runoff. Metals are much more likely to be detected in Crane Creek Arm which has the greatest
suspended solids concentrations and the Yadkin River appears to be a significant contributor of lead
and mercury. High Rock Reservoir is probably trapping many of these metals since detectable
occurrences are less frequent in Tuckertown Reservoir. It appears that almost all the mercury and
cadmium is being retained in High Rock Reservoir. The frequency of detectable levels of both lead
and copper decrease in the downstream reservoirs.
2.3.6 Seasonal and Annual Variability
Seasonal patterns in water quality are affected by differences among the years. In this study, 2002
was an usually dry year, flows and water levels in High Rock Reservoir reached "historic" lows.
Conversely, 2003 was an extremely wet year and flow and lake levels were near record highs. The
effects of extreme low flow and high flow years caused alterations in the typical seasonal trends in
those years. Seasonal trends are influenced by a number of factors, mostly related to climate and
biological activity. Land use practices and other human activities in the watershed that may affect
water quality may also vary both annually and seasonally.
The annual minimum and maximum surface temperatures are relatively consistent among the
reservoirs and among the years. Surface temperatures increase from winter lows of about 8°C to
summer highs of about 30°C (sections 2.3.1 to 2.3.4). Except for Narrows Reservoir, bottom
temperatures show a seasonal pattern that is similar to the surface. However, the summer maximum
is a little lower, with summer bottom temperatures reaching about 27°C. In High Rock, Tuckertown
and Falls reservoirs, weak thermal stratification of up to 4°C occurs in the summer, generally from
July to September. In Narrows Reservoir, a hypolimnion develops below a depth of 25 meters (82
Yadkin Project Water Quality Monitoring Study 41 Normandeau Associates
Water Quality
feet). The hypolimnion in Narrows Reservoir develops in spring and persists until December or
January. Epilimnetic temperatures in Narrows are similar to the other reservoirs during the summer.
Two distinct seasonal patterns were observed for dissolved oxygen concentrations in the photic zone.
In High Rock, Tuckertown and Narrows reservoirs in 2002, 2003 and to lesser extent, 2000, there
were two periods of high dissolved oxygen concentrations. In these years, dissolved oxygen
concentrations decreased from winter highs to moderate levels in late spring, returned to high levels
during the summer, decreased to moderate levels once again in early fall before returning to winter
levels in December. In contrast, dissolved oxygen concentrations in 1999 and 2001 decreased from
winter highs to late summer and early fall lows. Surface dissolved oxygen was generally lower in
1999 and 2001 with concentrations below 5 mg/l occurring occasionally in the late summer. The
summer increases in dissolved oxygen concentrations in 2000, 2002 and 2003 can be attributed to
algal production as oxygen is produced during photosynthesis.
Bottom dissolved oxygen concentrations in High Rock, Tuckertown and Narrows reservoirs were
relatively consistent among years. Concentrations decreased from winter highs to summer lows.
Low dissolved oxygen concentrations (<5 mg/1) typically occurred from May to October in High
Rock Reservoir, from May to November in Tuckertown and from April to December/January in
Narrows. Anoxia was generally limited to the summer months in High Rock and Tuckertown
reservoirs. The volume of the anoxic zone in High Rock and Narrows was reduced in 2002 during
the drawdown of the reservoirs as the surface oxygenated layer moved down with the water level and
the volume of hypolimnion was reduced.
The dissolved oxygen characteristics of Falls Reservoir are considerably different from the upstream
reservoirs. Anoxia is absent and differences between the surface and bottom waters are much more
limited than in the other reservoirs. Seasonally, dissolved oxygen concentrations decrease from
winter highs to summer lows in both the surface and bottom waters. Oxygen depletion below the
photic zone is limited to the summer months.
Suspended solid concentrations do not follow a seasonal pattern. There are large fluctuations,
especially in High Rock Reservoir, but the occurrence of the peak periods varies among the years
(Figure 2.3-5). The upper mainstem of High Rock Reservoir is strongly influenced by runoff from
the Yadkin River where suspended solids concentrations would be affected by precipitation and land
use in the upstream watershed. Increases of suspended solids in 2000, 2001 and 2002 in late spring
and early summer suggest the possibility of a weak seasonal trend in the lower mainstem and arms of
High Rock Reservoir. This trend was not observed in 1999 or 2003 however, suggesting that if
seasonal effects exist, they have less influence on suspended solid concentrations than other factors.
Suspended solid concentrations in the lower portion and arms of High Rock Reservoir were generally
independent of concentrations in the upper mainstem. There were no seasonal trends in Tuckertown
or Narrows Reservoirs. Suspended solid concentrations in Tuckertown Reservoir were generally
slightly greater when concentrations were higher in the lower portion of High Rock Reservoir.
Suspended solids are discussed further in Section 3.5.
Dissolved solids concentrations from 1999 to 2002 were generally greater in the late summer and fall
in High Rock and Tuckertown reservoirs (Figure 2.3-6). Peak concentrations in Narrows Reservoir
occurred in late fall or early winter suggesting a slight lag that may be related to the time required for
surface waters to travel through the system. There was also a slight lag at Tuckertown Reservoir
when compared to High Rock. In the low flow year of 2002, there was a two month lag between
High Rock and Tuckertown reservoirs and the increase in total dissolved solids concentrations that
Yadkin Project Water Quality Monitoring Study 42 Normandeau Associates
Water Quality
Figure 2.3-5
Figure 2.3-6
90.0
80.0
70.0
a
60.0
-c
50.0
b
b
5' 40.0
a.
30.0
0
h
20.0
10.0
0.00
JAN99 JUL99 JAN00 JUL00 JANOI JULOI JAN02 JUL02 JAN03 JUL03 JAN04
Date
Upper High Rock Mainstem
Lower High Rock Mainstem and Arms
Tuckertown Reservoir
Narrows Reservoir
Locally weighted estimates (LOWESS) of Total Suspended Solids
concentrations (mg/1) in the upper mainstem of High Rock, the lower mainstem
and arms of High Rock, Tuckertown and Narrows Reservoirs from June 1999 to
December 2003.
150.0
140.
130.
120.
on
d 110.
0
100.
0
90.0
fa
80.0
70.0
60.0
50.00
JAN99 JUL99 JAN00 JUL00 JANOI JULOI JAN02 JUL02 JAN03 JUL03 JAN04
Date
Upper High Rock Mainstem
Lower High Rock Mainstem and Arms
Tuckertown Reservoir
Narrows Reservoir
Locally weighted estimates (LOWESS) of Total Dissolved Solids
concentrations (mg/1) in the upper mainstem of High Rock, the lower mainstem
and arms of High Rock, Tuckertown and Narrows Reservoirs from June 1999 to
December 2003.
Yadkin Project Water Quality Monitoring Study 43 Normandeau Associates
Water Quality
typically occurs in Narrows Reservoir was not observed. The seasonal pattern was disrupted during
2003 when high flows occurred and total dissolved solids concentrations remained low throughout the
year.
Chlorophyll a concentrations, the surrogate measure for algal biomass, has a strong seasonal pattern
in the lower mainstem and arms of High Rock, Tuckertown and Narrows Reservoirs. Concentrations
are lowest in the early winter and increase to annual maxima in mid-summer (Figure 2.3-7). In the
upper mainstem of High Rock Reservoir, chlorophyll a concentrations are considerably more variable
and a strong seasonal pattern is not seen, although summer levels tend to be higher than late winter
and early spring. The greatest concentrations of chlorophyll a occurred in 2002, the low flow year,
but higher levels were only seen in High Rock and Tuckertown reservoirs. Peak chlorophyll a
concentrations in the high flow year, 2003 were about half the previous years. Algal biomass during
the summer of 2003 in Narrows was slightly greater than normal. This may have been due to
increased loading to Narrows Reservoir by the high flows. The decrease in High Rock and
Tuckertown reservoirs may have been caused by the shorter residence time of surface water in High
Rock not allowing the algal population to fully develop.
There does not appear to be a seasonal trend for total organic carbon (Figure 2.3-8). There was little
change in total organic carbon concentrations in 1999 and 2000, thereafter concentrations tended to
vary seasonally with the greatest concentrations occurring in 2002. Total organic carbon
concentrations in Tuckertown and Narrows reservoirs were almost identical both in terms of
magnitude and timing of peaks, except during the low flow year 2002. Concentrations in High Rock's
upper mainstem were much lower than in the lower mainstem and arms where a large algal
population develops. Total phosphorus concentrations fluctuate widely, especially in High Rock
Reservoir, but the variation is not related to season (Figure 2.3-9). Phosphorus concentration in both
the upper mainstem and the lower portion of the reservoir reflect changes in the suspended solid
concentrations (Figure 2.3-5). A large portion of the phosphorus entering High Rock Reservoir is
probably a constituent of particulate matter. Phosphorus concentrations in Tuckertown do not follow
a seasonal pattern and are generally unrelated to concentrations in High Rock Reservoir. Narrows
Reservoir phosphorus concentrations follow a trend similar to Tuckertown, but the magnitude is
slightly less.
Three of the principal constituents of the nitrogen cycle are ammonia, organic nitrogen and nitrous
oxides (generally nitrate). Of these three components, ammonia occurs in the lowest concentrations
in the surface waters of High Rock, Tuckertown and Narrows reservoirs. Ammonia concentrations
are much higher in bottom water, which are not considered here. There are no seasonal trends in
ammonia in any of the reservoirs (Figure 2.3-10). Total Kjeldahl Nitrogen (TKN) can provide a
rough estimate of organic nitrogen. Since ammonia levels were relatively low in comparison to TKN,
the plot of TKN approximates the organic nitrogen concentrations. There was no seasonal trend in
TKN concentrations in the upper mainstem of High Rock Reservoir which is influenced by the
Yadkin River, but a fairly consistent seasonal trend occurred in the lower mainstem and arm stations
where large algal populations develop (Figure 2.3-11). Low concentrations occurred in late winter
and early spring and high concentrations occurred in the summer, similar to the increase in
chlorophyll a concentrations. Except for 2000, seasonal trends were similar in Tuckertown Reservoir
and the lower portion of High Rock Reservoir. There were no apparent trends in Narrows Reservoir.
The amount of organic nitrogen entering High Rock in the upper mainstem is much lower than in the
lower portion of the reservoir. Organic nitrogen is being generated in the lower portion of High Rock
and the source of the nitrogen is nitrate. Nitrate concentrations are consistently high in the upper
Yadkin Project Water Quality Monitoring Study 44 Normandeau Associates
Water Quality
Figure 2.3-7
Figure 2.3-8
80.0
70.0
60.0
--' 50.0
on
40.0
a.
0
0
30.0
20.0
10.0
0.00
JAN99 JUL99 JAN00 JUL00 JANOI JUL01 JAN02 JUL02 JAN03 JUL03 JAN04
Date
Upper High Rock Mainstem
Lower High Rock Mainstem and Arms
Tuckertown Reservoir
Narrows Reservoir
Locally weighted estimates (LOWESS) of Chlorophyll a concentrations (ug/1)
in the upper mainstem of High Rock, the lower mainstem and arms of High
Rock, Tuckertown and Narrows Reservoirs from June 1999 to December 2003.
8.0
7.0
6b 6.0
0
U 5.0
v
on
O
' 4.0
0
h
3.0
2.00
JAN99 JUL99 JAN00 JUL00 JANOI JUL01 JAN02 JUL02 JAN03 JUL03 JAN04
Date
Upper High Rock Mainstem
Lower High Rock Mainstem and Arms
Tuckertown Reservoir
Narrows Reservoir
Locally weighted estimates (LOWESS) of Total Organic Carbon concentrations
(mg/1) in the upper mainstem of High Rock, the lower mainstem and arms of
High Rock, Tuckertown and Narrows Reservoirs from June 1999. to December
2003.
Yadkin Project Water Quality Monitoring Study 45 Normandeau Associates
Water Quality

0
0
a
0
JAN99 JUL99 JAN00 JUL00 JANOI JULOI JAN02 JUL02 JAN03 JUL03 JAN04
Date
Upper High Rock Mainstem
Lower High Rock Mainstem and Arms
Tuckertown Reservoir
Narrows Reservoir
Figure 2.3-9. Locally weighted estimates (LOWESS) of Total Phosphorus concentrations
(mg/1) in the upper mainstem of High Rock, the lower mainstem and arms of
High Rock, Tuckertown and Narrows Reservoirs from June 1999 to December
2003.
a
c?
en
0
z
0
d
0.24
0.23
0.22
0.21
0.20
0.19
0.18
0.17
0.16
0.15
0.14
0.13
0.12
0.11
0.10
0.09
0.08
0.07
0.06
0.05
JAN99
Figure 2.3-10. Locally weighted estimates (LOWESS) of Ammonia-nitrogen concentrations
(mg/1) in the upper mainstem of High Rock, the lower mainstem and arms of
High Rock, Tuckertown and Narrows Reservoirs from June 1999 to December
2003.
Yadkin Project Water Quality Monitoring Study 46 Normandeau Associates
JUL99 JAN00 JUL00 JAN01 JULO1 JAN02 JUL02 JAN03 JUL03 JAN04
Date
Upper High Rock Mainstem
Lower High Rock Mainstem and Arms
Tuckertown Reservoir
Narrows Reservoir
Water Quality
1.40
1.30
1.20
1.10
1.00
0
s.
z 090
b
0.a0
0.70
H
0.60
0.s0
0.40
Date
Upper High Rock Mainstem
Lower High Rock Mainstem and Arms
Tuckertown Reservoir
Narrows Reservoir
Figure 2.3-11. Locally weighted (LOWESS) estimates of Total Kjeldahl-nitrogen
concentrations (mg/1) in the upper mainstem of High Rock, the lower mainstem
and arms of High Rock, Tuckertown and Narrows Reservoirs from June 1999 to
December 2003.
portion of High Rock Reservoir, but they do not have a seasonal cycle (Figure 2.3-12). A very
consistent seasonal cycle with low nitrate concentrations in the summer and high concentrations in
the winter occurs in the lower portion of High Rock, and in Tuckertown and Narrows Reservoirs.
During the extremely low flow year of 2002, the seasonal nitrate cycle in the lower portion of High
Rock was altered and appeared related to the inflowing waters in the upper mainstem, but at much
reduced levels. The nitrate seasonal cycle in the lower portion of High Rock is the inverse of the
TKN and chlorophyll a seasonal cycles. The assimilation by algae and other microbial organisms of
nitrate is mostly limited to High Rock Reservoir passage of water through the other reservoirs has
little effect on nitrate concentrations.
2.3.7 Water Quality of Bottom Waters
In lake and reservoir environments, bottom waters often have different water quality characteristics
than the overlying surface water. A number of factors cause this including stratification caused by
temperature or density gradients, chemical reactions of water with the sediment, groundwater inflow,
available light and biological activity. Differences between the chemistry of the surface and bottom
water varies seasonally due to changes in climate that affect thermal stratification, dissolved oxygen
depletion and runoff.
During the summer, bottom collections in the four Yadkin River reservoirs are generally cooler and
have lower dissolved oxygen concentrations or are anoxic. In High Rock and Tuckertown reservoirs,
summer bottom collections are more turbid with greater concentrations of suspended solids, total
phosphorus and ammonia. Ammonia levels are also high in Narrows Reservoir in the bottom
collections.
Yadkin Project Water Quality Monitoring Study 47 Normandeau Associates
JAN99 JUL99 JAN00 JUL00 JAN01 JUL01 JAN02 JUL02 JAN03 JUL03 JAN04
Water Quality
1.30
1.20
1.10
1.00
0.90
a
0.80
0.70
on
0
0.60
z
0.50
Z 0.40
0.30
0.20
0.10
0.00
JAN99 JUL99 JAN00 JUL00 JANO1 JULO1 JAN02 JUL02 JAN03 JUL03 JAN04
Date
Upper High Rock Mainstem
Lower High Rock Mainstem and Arms
Tuckertown Reservoir
Narrows Reservoir
Figure 2.3-12. Locally weighted estimates (LOWESS) of Nitrate-nitrogen concentrations
(mg/1) in the upper mainstem of High Rock, the lower mainstem and arms of
High Rock, Tuckertown and Narrows Reservoirs from June 1999 to December
2003.
Turbidity and total suspended solids are greater in the bottom waters of High Rock and Tuckertown
Reservoirs (Figures 2.3-13 and 2.3-14). By the time waters reach Narrows and Falls Reservoirs,
concentrations are near the detection limit and differences between surface and bottom cease to exist.
Seasonally, differences between the surface and bottom are greatest in summer in High Rock
Reservoir where average bottom concentrations of suspended solids are almost four times greater than
the surface concentrations in summer. This can be attributed to lower summer flows which increase
retention time in High Rock Reservoir and allows more time for solids to settle. Bottom turbidity and
total suspended solids in Tuckertown Reservoir are consistently greater than the surface, but the
magnitude is rather small. Since most phosphorus appears to be particulate in origin (Section 2.3.6),
it is not surprising that total phosphorus concentrations in the bottom collections (Figure 2.3-15)
reflect changes in total suspended solids.
Ammonia concentrations are greater in the summer in all reservoirs except for Falls, where surface
and bottom concentrations are similar (Figure 2.3-16). Peak levels occur in July in High Rock and
Tuckertown reservoirs. In Narrows Reservoir, concentrations in July are similar to High Rock and
Tuckertown, but concentrations increase, rather than decrease, to very high levels in August.
Ammonia concentrations are related to anoxic conditions in the bottom waters of the reservoirs.
Ammonia is oxidized in the presence of dissolved oxygen and is produced by anaerobic micro-
organisms.
Nitrate-nitrogen concentrations were usually slightly greater in the bottom waters, but the differences
were small in High Rock, Tuckertown and Narrows Reservoirs. Large differences between surface
and bottom concentrations of nitrate were only observed in Narrows Reservoir (Figure 2.3-17).
Yadkin Project Water Quality Monitoring Study 48 Normandeau Associates
Water Quality
60
50
40
z
Z 30
a
F 20
10
0
60
50
3 40
z
30
a
F 20
10
0
60
50
40
z
30
a
F 20
10
0
60
50
3 40
z
30
a
F 20
10
0
Lower High Rock Mainstem and Arms
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Tuckertown
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Narrows
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Falls
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Figure 2.3-13. Monthly surface and bottom median turbidity (NTt? in the lower mainstem and
arms of High Rock, Tuckertown, Narrows and Falls Reservoirs. Data are from
1999 through 2003.
Yadkin Project Water Quality Monitoring Study 49 Normandeau Associates
Water Quality
40
J
o, 30
E
N
a
20
a
a
c
y 10
m
0
? 0
40
J
o, 30
E
N
a
20
a
a
c
y 10
m
0
0
40
J
o, 30
E
N
a
20
a
a
c
y 10
m
0
? 0
40
J
o, 30
E
N
a
20
a
a
c
y 10
m
0
0
Lower High Rock Mainstem and Arms
Bottom
Surface
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Tuckertown
- Bottom
Surface
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Narrows
Bottom
Surface
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Falls
Bottom
Surface
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Figure 2.3-14. Monthly surface and bottom median Total Suspended Solids (mg/1) in the lower
mainstem and arms of High Rock, Tuckertown, Narrows and Falls Reservoirs.
Data are from 1999 through 2003.
Yadkin Project Water Quality Monitoring Study 50 Normandeau Associates
Water Quality
Lower High Rock Mainstem and Arms
0.25
? 0.20
a
E
0.15
0
0 0.10
IL
m
F0 0.05
0.00
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Tuckertown
0.25
?T 0.20
m
E
2 0.15
0
00 0.10
IL
Co
0.05
0.00
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Narrows
0.25
? 0.20
a
E
0.15
0
0 0.10
IL
m
0.05
0.00
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Falls
0.25
0.20
m
2 0.15
0
00 0.10
IL
Co
0.05
0.00
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Figure 2.3-15. Monthly surface and bottom median Total Phosphorus (mg/1) in the lower
mainstem and arms of High Rock, Tuckertown, Narrows and Falls Reservoirs.
Data are from 1999 through 2003.
Yadkin Project Water Quality Monitoring Study 51 Normandeau Associates
Water Quality
1.0
0.9
J 0.8
m
0.7
c
0 0.6
0
0.5
z
m 0.4
c
E 0.3
Q 0.2
0.1
0.0
1.0
0.9
J 0.8
m
0.7
c
0 0.6
0
0.5
z
m 0.4
c
E 0.3
Q 0.2
0.1
0.0
1.0
0.9
J 0.8
m
0.7
c
0 0.6
0
0.5
z
m 0.4
c
E 0.3
Q 0.2
0.1
0.0
1.0
0.9
0.8
0.7
c
0 0.6
0
0.5
z
m 0.4
c
E 0.3
Q 0.2
0.1
0.0
Lower High Rock Mainstem and Arms
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Tuckertown
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Narrows
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Falls
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Figure 2.3-16. Monthly surface and bottom median Ammonia-nitrogen (mg/1) in the lower
mainstem and arms of High Rock, Tuckertown, Narrows and Falls Reservoirs.
Data are from 1999 through 2003.
Yadkin Project Water Quality Monitoring Study 52 Normandeau Associates
Water Quality
1.0
0.9
0.8
0.7
0.6
m
a 0.5
Z 0.4
E2 0.3
z 0.2
0.1
0.0
1.0
0.9
0.8
0.7
0.6
m
a 0.5
Z 0.4
E2 0.3
z 0.2
0.1
0.0
1.0
0.9
?y 0.8
0.7
0.6
m
a 0.5
Z 0.4
0.3
z 0.2
0.1
0.0
Lower High Rock Mainstem and Arms
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Tuckertown
1.0- Botto
0.9- Surface
0.8
0.7
0.6
m
a 0.5-
Z 0.4-
2 0.3-
z 0.2
0.1
0.0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Narrows
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Falls
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Figure 2.3-17. Median monthly Nitrate-Nitrogen concentrations (mg/1) in surface and bottom
collections from the lower mainstem and arms of High Rock and from
Tuckertown, Narrows and Falls Reservoirs. Data are from 1999 through 2003.
Yadkin Project Water Quality Monitoring Study 53 Normandeau Associates
Water Quality
Differences between surface and bottom occur from May to July coinciding with the development of
the thermocline and the isolation of hypolimnetic waters in Narrows Reservoir. Nitrate levels in the
hypolimnion remain at about the concentration of nitrate at the initiation of stratification until June.
The large decrease in nitrate concentration in July and August coincides with an increase of ammonia
that is equal in magnitude. Nitrate concentrations in Falls Reservoir, both surface and bottom,
generally follow the seasonal trend seen in the bottom waters of Narrows Reservoir.
Mercury concentrations are often greater under anoxic conditions. Detectable levels of mercury were
frequently observed in the hypolimnion of Narrows Reservoir (Section 2.3.5) although mercury was
not detected in fish (Section 3.6).
Total dissolved solids and biological oxygen demand concentrations are similar in the surface and
bottom collections. Total Kjeldahl nitrogen and total organic carbon are also similar in surface and
bottom collections in all reservoirs except for Narrows where small seasonal differences occur
(Appendix F).
Differences between the surface and bottom were negligible in the upper mainstem stations of High
Rock Reservoir where the depth is shallow and flow is occasionally seen (Appendix D contains
dissolved oxygen profiles of the High Rock stations). Stations in the lower mainstem and arms of
High Rock Reservoir and the other reservoirs are prone to oxygen depletion below the photic zone
and weak thermal stratification in the summer (Sections 2.3.1 through 2.3.4).
2.4 WATER QUALITY OF THE TAILRACES
2.4.1 Monthly Water Quality Monitoring
A downstream trend in median water quality values is apparent through the tailraces. This is mostly
due to changes in water quality between Tuckertown and Narrows tailraces (Table 2.4-1). Water
quality of High Rock and Tuckertown tailraces is fairly similar. These two tailraces are turbid,
nutrient rich and contain moderate amounts of algal biomass. Between Tuckertown and Narrows
tailraces there is a moderate reduction of ammonia, chlorophyll a, nutrients and solids. Water clarity
improves somewhat in the downstream tailraces. The water quality of Narrows and Falls tailraces is
almost identical. All four tailraces experience low dissolved oxygen concentrations, although median
concentrations are above the state standards. Dissolved oxygen in the tailraces is discussed in much
greater detail in Section 2.4.2. Despite the downstream trend, overall water quality does not differ
much among the four tailraces, percentiles tend to overlap for most of the parameters.
Water clarity, turbidity and the concentrations of solids and total nutrients in each tailrace are
generally similar to the surface water near the dam in the preceding reservoir. Tailraces differ from
reservoir stations in temperature, pH, dissolved oxygen, algal biomass, nitrate and ammonia (Section
2.2), which are parameters that exhibit differences between surface and bottom waters. The mixing
of water entrained over the wide depth range of the dam intakes alters the water quality of the
effluent. As differences between surface and bottom water occur seasonally, the effects of dam
passage should also vary seasonally.
Tailrace temperatures have a seasonal cycle that is similar to the cycle seen in the reservoirs (Figure
2.4-1). Temperatures were almost identical in the tailraces in 1999, 2000 and 2003. In the two years
with the lowest flow, 2001 and 2002, summer temperatures were slightly cooler in the Narrows and
Falls tailraces compared to High Rock and Tuckertown and the other years.
Yadkin Project Water Quality Monitoring Study 54 Normandeau Associates
Ch
Ch
z
O
4
<D
0)
n
H
H
O
n
<D
H
Table 2.4-1. Summary of monthly water quality monitoring data in tailraces (1999-2003).
Station
High Rock Tailrace Tuc kertown Tailrace Narrows Tailrace Falls Tailrace
Parameter 5% Median 95% 5% Median 95% 5% Median 95% 5% Median 95%
Temperature (deg C) 5.69 18.19 27.87 5.72 18.64 27.92 5.98 17.95 26.48 5.93 18.03 26.49
Dissolved Oxygen (mg/L) 2.66 7.83 11.43 1.03 6.54 11.39 3.64 7.84 11.13 4.47 7.72 11.43
pH (SU) 6.14 7.04 7.55 6.27 7.02 7.45 6.30 6.86 7.23 6.08 6.70 6.99
Conductivity (gmhos/cm) 54 116 157 53 114 154 55 110 132 54 108 133
Alkalinity (mg/1) 16 27 37 16 27 38 13 26 35 12 24 33
Biological Oxygen Demand
(mg/L) <2 2 6 <2 <2 5 <2 <2 4 <2 <2 3
Chemical Oxygen Demand
(mg/L) <20 <20 23 <20 <20 21 <20 <20 22 <20 <20 <20
Chlorophyll a (gg/L) 3.6 14.0 33.6 4.4 9.2 20.0 2.0 4.8 10.0 2.0 4.0 9.6
Total Organic Carbon
(mg/L) 2.4 3.7 6.3 2.6 3.6 6.7 2.6 3.4 5.2 2.7 3.4 5.1
Total Phosphorus (mg/L) 0.04 0.08 0.20 0.03 0.07 0.12 <0.02 0.04 0.15 <0.02 0.04 0.17
Total Nitrogen (mg/L) <0.5 1.15 1.66 <0.5 0.94 1.65 <0.5 0.75 1.48 <0.5 0.73 1.50
Ammonia-Nitrogen (mg/L) <0.05 0.12 0.35 <0.05 0.12 0.29 <0.05 0.06 0.15 <0.05 0.06 0.12
Nitrate-Nitrogen (mg/L) 0.07 0.46 0.88 0.09 0.47 0.87 0.05 0.45 0.76 0.09 0.50 0.74
Nitrite-Nitrogen (mg/L) <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1
Total Kjeldahl Nitrogen
(mg/L) <0.5 0.67 1.11 <0.5 0.63 1.01 <0.5 0.54 0.82 <0.5 0.52 0.81
Turbidity (mg/L) 9 17 43 6 12 39 2 4 19 2 4 18
Secchi Depth (m) 0.43 0.65 1.00 0.38 0.80 1.03 0.67 1.68 2.40 0.62 1.00 1.37
Total Solids (mg/L) 58 92 122 48 88 142 54 76 114 52 74 120
Total Dissolved Solids
(mg/L) 48 82 111 30 78 118 46 73 104 48 72 106
Total Suspended Solids
(mg/L) <5 10 17 <5 7 14 <3 <5 8 <3 <5 6
Cadmium (gg/L) <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5
Copper (gg/L) QO QO QO QO <10 12 QO QO QO <10 QO QO
Cyanide (mg/L) <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
Lead (gg/L) <2 <2 3.3 <2 <2 3.2 <2 <2 3.2 <2 <2 2.8
Mercury (gg/L) <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2

lD
"It
A
`C
Water Quality
The effects of dam operation on dissolved oxygen are covered in detail in Sections 3.3 and 3.4 of this
report. Seasonally dissolved oxygen concentrations average about 3 to 5mg/l in the summer in the
tailraces, especially High Rock and Tuckertown (Figure 2.4-2). Average dissolved oxygen
concentrations were particularly low in Tuckertown tailrace during the extreme low flow year of
2002. Average dissolved oxygen concentrations in daytime collections from the Narrows and Falls
tailraces were generally greater than 5 mg/l from 2001 to 2003 which includes the two lowest flow
years and the highest flow year. The high flow year, 2003, improved dissolved oxygen
concentrations in all the tailraces.
Median chlorophyll a concentrations in the tailraces are lower than the preceding reservoir (Table
2.4-1, Figure 2.2-3). Although chlorophyll a is not measured from bottom samples, concentrations
are assumed to be low because of the lack of solar radiation below the photic zone. In contrast to
High Rock and Tuckertown reservoirs, where surface chlorophyll a concentrations have a seasonal
cycle with a summer peak, tailrace chlorophyll a concentrations are relatively constant and generally
do not display seasonality (Figure 2.4-3). Chlorophyll a concentrations reached nuisance levels
(>30 gg11) in the High Rock tailrace during the summer of 2002, the extremely low flow year when
flow through High Rock and Tuckertown dams was minimal allowing for long retention time and the
development of large algal standing crops. Chlorophyll a concentrations in the Narrows and Falls
tailraces were almost identical.
Median nitrate-nitrogen concentrations are slightly greater in the tailraces than in the surface waters
of the preceding reservoir (Tables 2.3-1, 2.3-3 and 2.4-1). Seasonally, a slight lag in nitrate
concentrations occurs in Narrows and Falls tailraces when compared to High Rock and Tuckertown
(Figure 2.4-4).
Ammonia-nitrogen concentrations are greatest during the summer in the High Rock and Tuckertown
tailraces and have a strong seasonality (Figure 2.4-5). Ammonia concentrations in the High Rock and
Tuckertown tailraces are similar to concentrations that occur in the bottom water of the preceding
reservoir (Figure 2.3-16). In the Narrows and Falls tailraces, ammonia concentrations vary over a
much narrower range and lack a seasonal pattern. Despite, very high ammonia concentrations in the
hypolimnion near Narrows dam in late summer and early fall, ammonia concentrations in the tailrace
remain low. The hypolimnion in Narrows Reservoir develops below the level of the intakes.
2.4.2 Continuous Dissolved Oxygen and Temperature Monitoring in Tailraces
Monitoring Program
Temperature and dissolved oxygen were continuously monitored during the late spring through fall
below Narrows and Falls dams from 2000 through 2004 and below Tuckertown and High Rock dams
in 2003 and 2004. More limited monitoring occurred below High Rock and Tuckertown prior to
2003 (two 3-day periods). These data were consistent with observations made during the more
extensive monitoring effort conducted in 2003 and 2004 in terms of concentrations observed and
daily fluctuations in concentrations. These data were discussed in detail in Normandeau (2002).
Tailrace monitoring dates are presented in Table 2.4-2. A summary of meter performance and data
quality is presented in Appendix G. Meters were out of service for a total of 73 days out of a
cumulative total of nearly 3000 days of deployment. Thirty-seven of the out of service days were
attributed to high flow or low water level conditions. The locations of the monitors are provided in
Figures 2.4-6 through 2.4-9. The meters were set to record dissolved oxygen concentrations and
Yadkin Project Water Quality Monitoring Study 56 Normandeau Associates
Water Quality
U
30.0
20.0
on
H
10.0
0.00
JAN99 JUL99 JAN00 JUL00 JAN01 JUL01 JAN02 YUL02 JAN03 JUL03 JAN04
Date
High Rock Tuckertown Narrows Falls
Figure 2.4-1. Locally weighted estimates (LOWESS) of Temperature °C in High Rock,
Tuckertown, Narrows and Falls tailraces from June 1999 to December 2003.
12.0
11.0
10.0
9.0
a
8.0
0 7.0
' 6.0
0
Q
5.0
4.0
3.0
2.00
JAN99 JUL99 JAN00 JUL00 JAN01 JUL01 JAN02 YUL02 JAN03 JUL03 JAN04
Date
High Rock Tuckertown Narrows Falls
Figure 2.4-2. Locally weighted estimates (LOWESS) of Dissolved Oxygen (mg/1) in High
Rock, Tuckertown, Narrows and Falls tailraces from June 1999 to December
2003.
Yadkin Project Water Quality Monitoring Study 57 Normandeau Associates
Water Quality
50.0
40.0
a
on 30.0
0
20.0
U
10.0
0.00
JAN99 JUL99 JAN00 JUL00 JANO1 JULOl JAN02 YUL02 JAN03 JUL03 JAN04
Date
High Rock Tuckertown Narrows Falls
Figure 2.4-3. Locally weighted estimates (LOWESS) of Chlorophyll a (µg/1) in High Rock,
Tuckertown, Narrows and Falls tailraces from June 1999 to December 2003.
0.9
0.s
0.7
0.6
on
0.5
on
0
Z 0.4
Z 0.3
0.2
0.1
0.00
JAN99 JUL99 JAN00 JUL00 JANOI JULOI JAN02 JUL02 JAN03 JUL03 JAN04
Date
High Rock Tuckertown Narrows Falls
Figure 2.4-4. Locally weighted estimates (LOWESS) of Nitrate-Nitrogen (mg/1) in High
Rock, Tuckertown, Narrows and Falls tailraces from June 1999 to December
2003.
Yadkin Project Water Quality Monitoring Study 58 Normandeau Associates
Water Quality

0
z
0
High Rock Tuckertown Narrows Falls
Figure 2.4-5. Locally weighted estimates (LOWESS) of Ammonia-Nitrogen (mg/1) in High
Rock, Tuckertown, Narrows and Falls tailraces from June 1999 to December
2003.
Table 2.4-2. Dates of continuous tailrace monitoring in four Yadkin Project tailraces, 2000-
2004.
Years High Rock Tuckertown Narrows Falls
2000 Aug 3-Dec 31 Aug 3-Dec 31
2001 Jan 1-Feb 21 Jan 1-Jan 18
Apr 26-Dec 4 Apr 26-Dec 4
2002 Apr 27-Dec 9 Apr 27-Dec 9
2003 Apr 24-Dec 17 Apr 24-Nov 20 Apr 24-Dec 1 Apr 24-Dec 18
2004 Apr 22-Dec 2 Jul 1-Dec 2 Apr 22-Dec 2 Apr 22-Dec 2
Yadkin Project Water Quality Monitoring Study 59 Normandeau Associates
JAN99 JUL99 JAN00 JUL00 JANOI JULOI JAN02 JUL02 JAN03 JUL03 JAN04
Date
Water Quality
Figure 2.4-6. Transect locations in High Rock tailrace to confirm monitor placement.
Yadkin Project Water Quality Monitoring Study 60 Normandeau Associates
Water Quality
Figure 2.4-7. Transect locations in Tuckertown tailrace to confirm monitor placement.
Yadkin Project Water Quality Monitoring Study 61 Normandeau Associates
Water Quality
Figure 2.4-8. Transect locations in Narrows tailrace to confirm monitor placement.
Yadkin Project Water Quality Monitoring Study 62 Normandeau Associates
Water Quality
Figure 2.4-9. Transect locations in Falls tailrace to confirm monitor placement.
Yadkin Project Water Quality Monitoring Study 63 Normandeau Associates
Water Quality
temperature every 15 minutes. The meters were serviced once every week during the period of
deployment. During servicing one or two observations in the time series were deleted corresponding
to the time that the meter was out of the water.
Tailrace Mixing
The mixing characteristics of tailrace waters below the Narrows and Falls Dams were evaluated
monthly from August through November, 2001. The purpose of this effort was to insure that the
placement of the continuous dissolved oxygen and temperature monitors was representative. The
transect locations are presented in Figures 2.4-8 and 2.4-9. During each survey dissolved oxygen and
temperature profiles were recorded every 15 meters (50 feet) along each transect. Results of the
transect surveys are presented in Appendix H.
Temperatures over all transects were within 1.5°C of each other during the August survey and within
1 °C of each other on the other three sampling dates in the Narrows tailrace. Temperature changes
were even smaller in the Falls tailrace on all dates except October 31, 2001. Water levels in the Falls
tailrace on this date were extremely low due to the drawdown in the downstream impoundment on
this date.
Dissolved oxygen concentrations generally varied by less than I mg/l on each sampling date with a
few exceptions. Both Falls (I sampling date) and Narrows (2 sampling dates) tailraces experienced
greater variability at times. The lowest dissolved oxygen readings recorded on these dates were along
the transects immediately adjacent to the dams. It is believed that water was stranded between the
dam and the powerhouse discharges on these dates (transect I in both tailraces), and that water was
not representative of the main tailwater flow. On these sampling dates, the distribution of dissolved
oxygen concentrations among all other tailrace transects was much less variable.
The mixing characteristics of the tailrace waters below High Rock and Tuckertown dams was
evaluated in 2003 in a similar manner as Narrows and Falls. Transect locations are presented in
Figures 2.4-6 and 2.4-7. Results of these transect surveys are presented in Appendix H. As in the
Narrows and Falls tailraces, the dissolved oxygen concentrations and temperatures observed in the
High Rock and Tuckertown tailraces varied little during each of the seven tailrace surveys. At High
Rock, dissolved oxygen concentrations varied by less than 1.5 mg/l and temperature by less than
1.25°C during each of the surveys. The highest dissolved oxygen concentrations were typically close
to the dam while the lowest were typically farthest from the dam. At Tuckertown, dissolved oxygen
varied by less than I mg/l during five of the seven surveys and by slightly over I mg/l during the
other two. Temperature varied by less than 1.25 °C during each of the surveys.
The evaluation of tailrace mixing described above suggests that the continuous monitor placement in
all four tailraces is appropriate and representative of tailrace water quality.
Monitoring Results
Continuous monitoring data for all five field seasons are presented in Figures 2.4-10 through 2.4-13.
These figures present the minimum and maximum temperatures observed for each day and the
minimum and average dissolved oxygen concentrations observed. These dissolved oxygen results
can be directly compared with the North Carolina Water Quality Standard of 4 mg/l for instantaneous
concentrations and 5 mg/l for a daily average. Raw data from the continuous monitoring program are
Yadkin Project Water Quality Monitoring Study 64 Normandeau Associates
Water Quality
High Rock
2003-2004
35 16
30 14
0 25 12

20 _
10
E
15 O
Q
5 mg/I 6
E 10
IN
4
(D
5 4 mg/I
2
0 0

Jan-03 Apr-03 Jul-03 Oct-03 Feb-04 May-04 Aug-04 Dec-04
MaxTemp MinTemp - MeanDO - MinDO
Figure 2.4-10. Continuous dissolved oxygen and temperature data at High Rock Tailrace
2003-2004.
Tuckertown
2003-2004
35 16
30 14
0 25 12
20 10

a)
15 l8 E
O
t
0- 5 mg/I 6 0
? 10 4
4 mg/I ?
5 d 2
0 0

Jan-03 Apr-03 Jul-03 Oct-03 Feb-04 May-04 Aug-04 Dec-04
MaxTemp MinTemp -MeanDO -MinDO
Figure 2.4-11. Continuous dissolved oxygen and temperature data at Tuckertown Tailrace
2003-2004.
Yadkin Project Water Quality Monitoring Study 65 Normandeau Associates
Water Quality
Narrows
1999-2000
35 16
U 30 14
0 25 12
20 10
?
m 15 5 mg/I 8
6 pQ
E 10 4
H 5 4 mg/I
2
0 0
Jan-99 Apr-99 Jul-99 Oct-99 Feb-00 May-00 Aug-00 Dec-00
MaxTemp MinTemp - MeanDO - MinDO
Narrows
2001-2002
35 16
30
0
? 14
25 12 ,.
20 10 a,

E
8
12 15 5 mg/I

10 7 :1

i 6 D

4
4 mg/I 1
H
5 ?° d

2
0 0

Jan-01 Apr-01 Jul-01 Oct-01 Feb-02 May-02 Aug-02 Dec-02
MaxTemp MinTemp - Me anDO - MinDO

Narrows
2003-2004
35 16
v 30 14
0 25 12 ,.
20 10
L 1
aa) 15 5 mg/I ?
6 0
E 10 4
5 4 mg/I
2
0 0

Jan-03 Apr-03 Jul-03 Oct-03 Feb-04 May-04 Aug-04 Dec-04
MaxTemp MinTemp -Me anDO - MinDO
Figure 2.4-12. Continuous dissolved oxygen and temperature data at Narrows Tailrace 2003-
2004.
Yadkin Project Water Quality Monitoring Study 66 Normandeau Associates
Water Quality
Falls
1999-2000
35 16
- 30 14
0 25 12
20 10
E
?
m- 15
5 mg/I 8
6 p
E 0
10 4
1- (D 5 4 mg/I 2
0 0

Jan-99 Apr-99 Jul-99 Oct-99 Feb-00 May-00 Aug-00 Dec-00
MaxTemp MinTemp - MeanDO - MinDO

Falls
2001-2002
35 16
30 14
° 25 12

a-) 20
1
0 E

E
15 8
n
5 mg/I »
6 p
E 10 4
5 4 mg/I ?u 2
0 0

Jan-01 Apr-01 Jul-01 Oct-01 Feb-02 May-02 Aug-02 Dec-02
MaxTemp MinTemp - MeanDO - MinDO

Falls
2001-2002
35 16
30 14
0 25 E 12

20
15 J

' O
U
E
n 5 mg/I V 6 p
E 10 4
5 4 mg/I 2
0 0

Jan-03 Apr-03 Jul-03 Oct-03 Feb-04 May-04 Aug-04 Dec-04
MaxTemp MinTemp - MeanDO - MinDO
Figure 2.4-13. Continuous dissolved oxygen and temperature data at Falls Tailrace 2003-2004.
Yadkin Project Water Quality Monitoring Study 67 Normandeau Associates
Water Quality
presented in Appendix I on the attached CD. These data provide information on the daily variation
that occurs in the tailraces below the dams.
Metrics used to evaluate the dissolved oxygen concentration in the four tailraces are presented in
Table 2.4-3. This table shows the number of days each year that the observed dissolved oxygen was
less than 5 mg/l daily average or the minimum observed dissolved oxygen for the day was below 4
mg/1. 5 mg/1 represents the North Carolina Standard for daily average dissolved oxygen
concentration while 4 mg/l is the standard for instantaneous dissolved oxygen concentration.
Table 2.4-3. Number of monitored days each project tailrace was below specific dissolved
oxygen concentrations.
2000 2001 2002 2003 2004
High Rock <5 mg/1' NS4 NS NS 49 107
<4 mg/l2 NS NS NS 33 96
Tuckertown <5 mg/1' NS NS NS 48 62
<4 mg/12 NS NS NS 36 55
Narrows <5 mg/1' 23 11 54 79 75
<4 mg/12 34 57 95 78 91
Falls <5 mg/1' 35 35 48 19 4
<4 mg/12 32 35 46 9 5
' based on daily average concentration.
2 based on at least one 15 minute reading below 4 mg/l per day.
3 commons monitoring initiated 08/03/00.
4 NS - not sampled.
High Rock
The typical pattern at High Rock shows adequate dissolved oxygen resources coupled with lower
water temperatures in the spring and fall and depressed dissolved oxygen concentrations through the
summer period (Figure 2.4-10). The onset of low dissolved oxygen concentrations in early July of
2003 (a wet year), was later than that observed in 2004 (mid-May), a year with more typical flows.
Dissolved oxygen concentrations increased by early September in both years. Daily average
temperatures in the High Rock tailrace peaked at approximately 27°C in 2003 and 28°C in 2004.
Diurnal fluctuation in tailrace dissolved oxygen concentrations was determined to be approximately 3
mg/l during two low river flow, high water temperature surveys in 2001 (Normandeau 2002). These
results are consistent with observations from the summers of 2003 and 2004 under similar conditions.
Table 2.4-3 summarizes the number of days that individual readings were below 4 mg/1 and daily
averages were below 5 mg/l over the two field seasons. In 2003, an abnormally wet year, the number
of days that dissolved oxygen was below these benchmarks was less than half those observed in 2004,
an average year in precipitation and discharge.
Low dissolved oxygen in the High Rock tailrace is a direct reflection of low dissolved oxygen in the
upstream impoundment. The low dissolved oxygen concentrations occur in response to the sinking of
algal cells out of the photic zone and subsequent aerobic decay in the lower depths of the
impoundment. When flows are high, water in the impoundment is exchanged more rapidly, reducing
the time that decomposition of algal cells consumes oxygen in the deep layers and diluting poorly
oxygenated water in the reservoir with oxygenated inflow water. This translates into relatively higher
Yadkin Project Water Quality Monitoring Study 68 Normandeau Associates
Water Quality
dissolved oxygen concentrations in the tailrace. In addition, during periods of high flow through the
reservoir, floodgates are frequently opened and spill further aerates tailrace waters. The effect of
generation on tailrace dissolved oxygen and temperature is discussed further in Sections 3.3 and 3.4.
The 2002 drought related drawdown of High Rock reservoir afforded an opportunity to examine the
influence of water level on downstream dissolved oxygen resources. Although continuous tailrace
dissolved oxygen data were not collected prior to 2003 in the High Rock tailrace, monthly
measurements of dissolved oxygen are available. In a typical flow year, dissolved oxygen is depleted
in High Rock reservoir throughout the entire depth of the intakes during the summer and early fall.
Oxygenated water is found above the uppermost level of the intakes. This is illustrated in Figure 2.4-
14. Water levels in 2001 were near the long term average level throughout the summer season
(Figure 1.0-2). Water with low dissolved oxygen concentrations was drawn into the intakes resulting
in low dissolved oxygen concentrations in the tailrace. In 2002, water levels in High Rock
impoundment in mid-summer were five meters lower than in a typical year (Figure 2.4-15). Surface
waters, oxygenated by a combination of surface mixing and photosynthesis, were found at the depth
of the turbine intakes during the drawdown. In addition, the volume of water in the impoundment
with lower dissolved oxygen concentrations was reduced relative to a typical year. As a result,
observed tailrace dissolved oxygen concentrations were higher in 2002 than in a typical year and were
generally greater than 5 mg/1.
Tuckertown
Dissolved oxygen concentrations in the Tuckertown tailrace showed a similar pattern to those
observed in the High Rock tailrace (Figure 2.4-11). High concentrations observed in the spring and
late fall were associated with high flows and low water temperatures and lower concentrations were
observed in the summer and early fall. The close association of water quality between the two
tailraces is likely a function of the short time of travel of water through Tuckertown Reservoir due to
its small size and the coordination of operations between High Rock and Tuckertown dams.
Maximum temperatures in the Tuckertown tailrace were 1-2°C higher than those observed in the High
Rock tailrace, peaking at approximately 29°C in 2003 and 30°C in 2004. As observed in High Rock
tailrace, there were fewer days in 2003 than 2004 when dissolved oxygen concentrations at
Tuckertown were less than 4 mg/l for a 15-minute reading or 5 mg/1 for a daily average (Table 2.4-3).
As in High Rock, this is attributed to high flows through the system during 2003, flushing waters with
low dissolved oxygen from the Tuckertown impoundment as well as the frequency of spill events at
the High Rock and Tuckertown dams during the summer of 2003. Data are presented in Appendix I.
Narrows
A time series of dissolved oxygen and temperature for the Narrows tailrace is presented in Figure 2.4-
12 for the monitoring period of 2000 through 2004. Continuous monitoring data can be found in
Appendix I. In Narrows Dam tailrace, summer daily change in dissolved oxygen was usually about 3
mg/1. Dissolved oxygen concentrations less than 4 mg/1 were frequently observed from June through
October, and periodically in May and November. Peak summer water temperatures were generally
between 26 and 27 °C and varied by only a few degrees each day. The number of days when
dissolved oxygen concentrations at Narrows were less than 4 mg/l for one reading or 5 mg/1 for a
daily average are summarized in Table 2.4-3. Results from 2000 cannot be used for comparison as
monitoring did not commence until August 3. During 2001 there were relatively few days (11) when
Yadkin Project Water Quality Monitoring Study 69 Normandeau Associates
Water Quality
LVV
195
190
c
°- 185
m
a?
w 180
175
170
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
14-
12-
10-
J
-
E 8
O 6-
C) 4
2
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 2.4-14. Dissolved oxygen (mg/1) in High Rock Reservoir and Tailrace 2001 (horizontal
lines in top panel represent intake interval) (y axis scale of 170 to 200 m is
equivalent to 558 to 656 ft).
200
195
190
C
°- 185
m
ED 180
175
170
14--
12-
10-
J
-
E 8
O 6-
r)
4-
2-

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
0
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Figure 2.4-15. Dissolved oxygen (mg/1) in High Rock Reservoir and Tailrace 2002 (horizontal
lines in top panel represent intake interval) (y axis scale of 170 to 200 m is
equivalent to 558 to 656 ft).
Yadkin Project Water Quality Monitoring Study 70 Normandeau Associates
Water Quality
the daily average dissolved oxygen concentration was below 5 mg/l compared to 2002, 2003 or 2004
(54-79). Likewise, the days when the minimum dissolved oxygen concentration was less than 4 were
fewer (57) than observed in 2002, 2003 or 2004 (78-95). Unlike at High Rock or Tuckertown, there
does not appear to be any clear relationship between hydrometeorologic conditions and the frequency
of low tailrace dissolved oxygen concentrations at Narrows tailrace. Results from 2002, one of the
driest on record are similar to those observed for 2003 one of the wettest on record. One potential
explanation for this finding is the location of the spillway at Narrows, well downstream of the
continuous monitor. During periods of spill, water returning to the mainstem from the side-channel
spillway is not represented at the continuous monitor. In addition, the depth of the intakes at Narrows
is sufficient to entrain water with low dissolved oxygen even under high flow conditions. The
influence of dam operations on tailrace dissolved oxygen concentrations is discussed in Sections 3.3
and 3.4.
Falls
The dissolved oxygen concentrations in Falls are strongly influenced by operations and dissolved
oxygen conditions at Narrows (Figure 2.4-13). The Falls impoundment does not stratify and the time
of travel through the Falls impoundment is so rapid that water passing the Falls dam is similar to
water passing through Narrows dam. Temperatures in the Falls tailrace were similar to those
observed in the Narrows tailrace reaching a summer maximum of 26-28°C (Figure 2.4-13).
Dissolved oxygen concentrations were generally higher in the Narrows tailrace than at the other three
projects with fewer days with one reading below 4 mg/l and fewer days with an average below 5 mg/l
(Table 2.4-3. Beginning in 2002, APGI started operating Narrows Unit 4 exclusively with 2 air
valves and is the first unit brought on line and the last taken off line during periods of generation for
the period May through November. The influence of air injection at Unit 4 via the air valves is
discussed further in Section 3.3. Data are presented in Appendix I.
2.5 STATE STANDARDS AND HISTORICAL DATA
State Standards and the Yadkin APGI Reservoirs
North Carolina has established a set of water quality standards (Administrative Code Section 15A
NCAC 2B .0200). The basic standard, designated Class C, applies to all surface waters and states that
the waters "shall be suitable for aquatic life propagation and maintenance of biological integrity,
wildlife, secondary recreation, and agriculture..." Additional standards apply to specific classes of
waters. Among these are water bodies that are used as drinking water supply or are immediately
upstream of a drinking water supply (Class WS). Both Class C and Class WS standards apply to all
waters in the four Alcoa reservoirs. Each standard lists a variety of water quality parameters along
with acceptable ranges. Water quality parameters and their standards that are relevant to the current
survey are presented in (Table 2.5-1). Tabulation of contaminations of water quality standards from
the monthly water quality monitoring program are presented in Tables 2.5-2 and 2.5-3.
The effects of the four reservoirs on dissolved oxygen concentrations in the tailraces are covered in
detail in other sections of this report (Table 2.4-3). Relative to state standards, low dissolved oxygen
concentrations in the surface waters are frequently observed in High Rock Reservoir, in particular, the
upper arms, and in the tailraces below each dam. Surface dissolved oxygen concentrations are
occasionally below standards in Tuckertown and Falls Reservoirs during the warmer months. Surface
Yadkin Project Water Quality Monitoring Study 71 Normandeau Associates
Water Quality
Table 2.5-1. Parameters measured in this study that have applicable North Carolina Water
Quality Standards.
NC Standard

Parameter Class C
Aquatic Life Class WS
Drinking
Water
Chlorophyll a <40 ?tg/l
Dissolved Oxygen >5.0 mg/1 daily average and
>4.0 mg/1 instantaneous
PH 6.0 to 9.0
Temperature <32°C and
<2.8°C above natural temperature
Turbidity <25 NTU
Cadmium <2.0 ?tg/l
Cyanide <5.0 ?tg/l
Lead <25 ?tg/l
Mercury 0.012 ?tg/l
Copper 7 /l Action Level
Total Dissolved Solids <500 mg/1
Nitrate Nitrogen <10.0 mg/1
dissolved oxygen concentrations in Narrows Reservoir exceed state standards. Oxygen depletion
occurs below the photic zone in High Rock, Tuckertown and Narrows reservoirs.
Summer temperatures in the reservoirs are generally well below the 32°C state standard (Figure 2.2-4
and Section 2.3.1). The operation of the hydroelectric facilities does not produce a heated discharge
and tailrace temperatures are similar to reservoir temperatures. There are two instances when
temperature exceeded 32°C, (Appendix J). In both cases, it is the surface reading on a hot sunny day
in an arm of High Rock Reservoir.
Surface pH at the reservoir stations occasionally exceeds the state standard. The 95th percentile of pH
at lake stations exceeds the upper limit of the state standard of nine units (Figure 2.2-4). High pH is
most frequently seen during the summer, in High Rock, Tuckertown and Narrows reservoirs and is
usually associated with high dissolved oxygen and chlorophyll a concentrations. The high pH levels
are limited to the photic zone and indicate intense algal productivity. Surface water pH at the upper
High Rock mainstem stations and in the tailraces usually exceeds the lower limit of the state pH
standard. The 5th percentile is slightly greater than six in these areas, but there are occasional
occurrences below the state pH standard at these sites. Low pH is frequently seen in the hypolimnion
of Narrows Reservoir.
Turbidity and chlorophyll a levels in High Rock and Tuckertown reservoirs frequently exceed the
state standards. Average turbidity in High Rock Reservoir is near the state standard (Figure 2.2-2).
About 25% of the chlorophyll a samples in High Rock Reservoir exceed the state standard (Figure
2.2-3). High Rock Reservoir is the first major impoundment on the Yadkin River and it receives a
large suspended solid and nutrient load from surface runoff. The nutrients are exploited by algae in
the arms and lower portion of the reservoir where large standing crops of phytoplankton develop.
The combination of a large phytoplankton standing crop and large amounts of suspended sediments
causes excessively high turbidity. These conditions also occur in Tuckertown Reservoir, but they
occur much less frequently and the magnitude is greatly reduced.
Yadkin Project Water Quality Monitoring Study 72 Normandeau Associates
Water Quality
Table 2.5-2. Number of samples that exceeded state standards for chlorophyll a, turbidity, total dissolved solids, cadmium, copper, cyanide, lead and mercury during the monthly water quality monitoring program (1999-2003).
Chlorophyll a
>40 u 1 Turbidity
>25 NTU Total Dissolved Solids
>500m /l Cadmium
>2u /l Copper
>7u 1 Cyanide
>5u /l Lead
>25u /l Mercury
>0.012u 1

Reservoir
Station Total
Sample s Exceed
Standard
% Total
Samples Exceed
Standard
% Total
Samples Exceed
Standard
% Total
Samples Exceed
Standard
% Total
Samples Exceed
Standard
% Total
samples Exceed
Standard
% Total
samples Exceed
Standard
% Total
Samples Exceed
Standard
%
Hi Rock Arms H2 55 16 29.1 105 86 81.9 105 105 105 5 4.8 105 3 2.9 105 105 4 3.8
H4 55 25 45.5 105 81 77.1 105 105 105 15 14.3 105 7 6.7 105 1 1.0 105 3 2.9
H5 55 26 47.3 106 62 58.5 106 106 106 8 7.5 106 6 5.7 106 106 2 1.9
H6 55 17 30.9 108 52 48.1 108 108 108 9 8.3 108 3 2.8 108 1 0.9 108 2 1.9
H8 55 17 30.9 108 54 50.0 108 108 108 3 2.8 108 3 2.8 108 108 1 0.9
H9 54 9 16.7 106 24 22.6 106 1 0.9 106 106 6 5.7 106 1 0.9 106 106
Hi Rock - Upper Mainstem Hl 55 1 1.8 108 73 67.6 108 1 0.9 108 1 0.9 108 10 9.3 108 1 0.9 108 1 0.9 108 8 7.4
H3 52 102 84 82.4 102 102 102 9 8.8 102 3 2.9 102 1 1.0 102 2 2.0
Hi Rock - Lower Mainstem H7 54 13 24.1 106 56 52.8 106 106 106 6 5.7 106 3 2.8 106 1 0.9 106
H10 55 6 10.9 108 47 43.5 108 108 108 6 5.6 108 2 1.9 108 108 1 0.9
Tuckertown Reservoir T2 55 9 16.4 108 21 19.4 108 1 0.9 108 1 0.9 108 6 5.6 108 3 2.8 108 108
T3 55 3 5.5 108 26 24.1 108 108 108 5 4.6 108 1 0.9 108 108
Narrows Reservoir NI 55 54 5 9.3 54 54 54 4 7.4 54 2 3.7 54 54 1 1.9
N2 55 108 15 13.9 108 107 107 1 0.9 107 3 2.8 107 107
N3 55 108 5 4.6 108 107 107 1 0.9 107 1 0.9 107 107
Falls Reservoir F2 55 108 4 3.7 108 107 107 3 2.8 107 7 6.5 107 107 1 0.9
Tailraces TI 55 2 3.6 108 23 21.3 108 108 108 2 1.9 108 2 1.9 108 108
N4 55 108 14 13.0 108 107 107 107 3 2.8 107 107 23 21.5
F1 55 54 2 3.7 54 54 54 54 1 1.9 54 54 1 1.9
F3 55 54 2 3.7 54 54 54 54 1 1.9 54 54 1 1.9
Yadkin Project Water Quality MonHodngStudy 73 Normandeau Associates
Water Quality
Table 2.5-3. Number of measurements that exceeded state standards for temperature,
dissolved oxygen and pH during the monthly water quality monitoring program
(1999-2003).
Temperature
>32°C DO
<4.0 m /l Ph
<6 or 9>
Total N Exceed % Total N Exceed % Total N Exceed %
High Rock Arms H2 212 207 37 17.87 207 13 6.28
H4 188 1 0.53 186 29 15.59 186 13 6.99
H5 345 340 50 14.71 340 22 6.47
H6 632 622 139 22.35 622 32 5.14
H8 400 1 0.25 394 73 18.53 394 17 4.31
High Rock - Upper mainstem Hl 272 265 0 0.00 265 8 3.02
H3 176 174 1 0.57 174 0 0.00
High Rock - lower mainstem H7 380 375 26 6.93 375 10 2.67
H9 487 479 83 17.33 479 27 5.64
H10 836 822 197 23.97 822 38 4.62
Tuckertown Reservoir T2 489 489 57 11.66 483 19 3.93
T3 999 999 257 25.73 982 62 6.31
Narrows Reservoir N2 1046 1046 198 18.93 1028 23 2.24
N3 1216 1216 300 24.67 1198 25 2.09
N4 2775 2775 1170 42.16 2725 187 6.86
Falls Reservoir F2 973 973 107 11.00 958 33 3.44
Tailraces TI 203 203 34 16.75 200 4 2.00
NI 179 179 41 22.91 178 4 2.25
F1 212 212 20 9.43 209 4 1.91
F3 109 109 4 3.67 108 4 3.70
Five toxic substances (lead, cadmium, copper, cyanide and mercury) were monitored in this survey.
Detectable levels of lead occurred in every reservoir and cadmium was detected in High Rock,
Tuckertown and Falls reservoirs (Section 2.3.5). However, most of these measurable concentrations
of lead and cadmium were below the state standards. There were five samples, all from High Rock
Reservoir, where concentrations exceeded the state standard (Appendix J). There were two samples
that contained cadmium concentrations above the state standard, one from High Rock near the mouth
of the Yadkin River and the second in Tuckertown Reservoir. The analytical detection limits for the
copper, cyanide and mercury are at or are slightly greater than the state standards and these toxic
substances are discussed in Section 2.3.5.
In addition to the Class C standards, drinking water standards apply to all waters of the four
reservoirs. Nitrate concentrations never occurred at concentrations exceeding the drinking water
standard of 10 mg/1. Total dissolved solids usually did not exceed 150 mg/1 but there were three
samples that contained concentrations that exceeded the state standard of 500 mg/l (Appendix J)
About 2000 samples were analyzed in this survey. State standards for lead, cadmium, nitrate and
total dissolved solids were rarely exceeded. Cyanide, copper and mercury were more likely to occur
at concentrations that exceed state standards. For most stations, concentrations of cyanide, copper
and mercury exceeded state standards on less than 13% of the sampling dates (Table 2.3-7).
Yadkin Project Water Quality Monitoring Study 74 Normandeau Associates
Water Quality
Historical data from the four reservoirs and long-term trends
Historical data on the water quality of the four Alcoa reservoirs on the Yadkin River are limited. A
survey of the American water willow in Narrows Reservoir was conducted from 1999 to 2001
included some nutrient data collected in the nearshore environment (Touchette, B. W. et al. 2001).
The concentrations of nitrate, ammonia, TKN and total phosphorus were similar to results obtained in
this survey in the more open water sites.
The State of North Carolina Department of Environment and Natural Resources, Division of Water
Quality (DWQ) has conducted water quality sampling in all four reservoirs. The earliest observations
obtained from DWQ are from 1981, and the data record is not continuous. It contains periodic water
quality measurements in Falls and Tuckertown impoundments and more frequent observations in
Narrows and High Rock reservoirs. Data were collected from eight stations in High Rock Reservoir,
four stations in Badin Lake (Narrows), and two stations each in Tuckertown Reservoir and Falls
Lake. Samples were generally collected once per year from June through September, although
limited additional data are available in some years. Parameters include dissolved oxygen,
temperature, pH, conductivity, Secchi transparency, nutrients including phosphorus and nitrogen,
chlorophyll a, solids and turbidity from the surface waters. Recent (1996-2000) chlorophyll a data
are suspect due to laboratory irregularities (Owen personal communication) and were disregarded.
Although DWQ historic data and the current survey differ in the number of stations and sampling
months, an attempt was made to equate the two sets of data as much as possible for comparative
purposes. Only stations located in similar areas were used. Since most DWQ sampling was
conducted in July and August, the APGI/NAI survey medians were recalculated using only July and
August, as well. DWQ sampling was conducted annually from 1981 to 1986, thereafter sampling
occurred about every three years and the two periods are presented separately. A Wilcoxon signed-
rank test was used to compare the current survey with the DWQ data from 1981 to 1986. The number
of samples was insufficient in the other three reservoirs for this test.
Over the 22 year period from 1981 to 2003, the water quality of the four reservoirs has remained
relatively similar. Concentrations of nutrients are currently and historically been at levels that can
support considerable algal growth (Table 2.5-4). Suspended and dissolved solids concentrations are
currently at levels that existed in the early DWQ sampling. Small but significant differences exist
between the early sampling (1981 to 1986) and the current sampling. Concentrations of total
phosphorus and all forms of nitrogen are slightly greater in recent years. Nitrogen levels are also
slightly greater in the other reservoirs as well. In High Rock Reservoir, waters are currently slightly
more turbid, have greater conductivity and lower dissolved oxygen and pH when compared to the
earlier sampling.
The DWQ station in the upper portion of High Rock Reservoir closest to the mouth of the Yadkin
River is somewhat downstream from current survey station (111) and the number of samples is rather
limited so assessment of trends should be made with caution. A large increase in nitrate
concentrations entering High Rock Reservoir occurred after 1986 and, this coincided with a large
decrease in chlorophyll a concentrations during the same period. Water clarity is slightly better
during the summer months in the current survey (1999 to 2003). Secchi depth increases while both
turbidity and total suspended concentrations decrease from the early DWQ sampling to the current
survey.
Yadkin Project Water Quality Monitoring Study 75 Normandeau Associates
Water Quality
A review of water quality data for High Rock was recently completed (TetraTech 2004) for the NC
DWQ in support of Total Maximum Daily Load (TMDL) evaluations for High Rock Lake. Upper
High Rock Lake is listed as impaired due to chlorophyll a, low dissolved oxygen and turbidity in the
North Carolina 2004 draft 303d list. Abbotts Creek is listed as impaired for dissolved oxygen and
turbidity and lower High Rock Lake is listed for dissolved oxygen and turbidity. The report suggests
that DWQ will be removing the low dissolved oxygen listing for all segments of High Rock
Reservoir. The review acknowledges the short residence time of High Rock lake as well as the high
inputs of suspended solids, phosphorus and nitrogen. Algal production based on historic chlorophyll a
data is thought to be controlled by light availability and flushing with a "diminished response to
nutrients." The report concludes that High Rock retains both suspended solids and phosphorus but
may be a net exporter of nitrogen due to nitrogen fixation by blue-green algae and ammonia release
from the sediments under anoxic conditions. It should be noted that the conclusions of this review
were based largely on data collected by NCDEWQ. Although the authors review the 2002 interim
report prepared for Yadkin APGI (Normandeau 2002), the data analysis apparently did not include
the extensive data set collected as a part of the Yadkin APGI relicensing effort. Nonetheless, the
conclusions drawn from the TetraTech review are generally consistent with the conclusions drawn for
High Rock Reservoir in this report.
Yadkin Project Water Quality Monitoring Study 76 Normandeau Associates
Water Quality
Table 2.5-4. Comparison of historical water quality data with current data.
High Rock (Stations 3,6,7,10)
NCDWQ 1981-86 NCDWQ 1987+ Current Survey
Parameter 5% Median 95% 5% Median 95% 5% Median 95% Prob> IZI
Temperature (deg C) 24.0 28.5 32.2 25.0 28.1 30.2 25.3 28.5 30.4
Dissolved Oxygen
(mg/L) 6.9 9.7 11.9 6.0 8.4 11.7 2.5 7.3 12.8 <0.01
pH 6.5 8.7 9.7 7.0 8.5 9.2 6.5 7.9 9.5 <0.01
Conductivity 73.0 102.0 124.0 79.0 115.5 137.0 77 139 206 <0.01
Secchi Depth (m) 0.1 0.6 1.2 0.3 0.7 1.0 0.2 0.7 1.0
Turbidity (NTU) 3.0 6.9 33.0 4.3 6.4 28.0 5 12 68 0.02
Total Dissolved Solids
(mg/L) 81.0 97.0 140.0 72.0 97.5 120.0 46 90 162
Total Suspended
Solids (mg/L) 8.0 12.0 47.0 2.0 9.0 26.0 5 12 44
Chlorophyll a (gg/1) 4.0 33.0 63.0 10.0 22.0 58.0 12 34 147
Total Phosphorus
(mg/L) 0.1 0.1 0.2 0.0 0.1 0.2 0.02 0.08 0.26 0.01
Total Nitrogen (mg/L) 0.5 0.6 2.2 0.3 0.5 1.3 0.59 1.09 2.35 <0.01
Nitrate-Nitrogen
(mg/L) 0.0 0.1 0.8 0.0 0.1 0.5 0.05 0.13 1.08
Ammonia-Nitrogen
(mg/L) 0.0 0.0 0.7 0.0 0.0 0.3 0.05 0.05 0.24 <0.01
Total Kjeldahl
Nitrogen (mg/L) 0.4 0.5 1.4 0.3 0.4 0.8 0.50 0.87 1.78 <0.01
Tuckertown
NCDWQ 1981-86 NCDWQ 1987+ Current Survey
Parameter 5% Median 95% 5% Median 95% 5% Median 95%
Temperature (deg C) 24.0 28.3 32.0 25.2 27.0 30.0 25.4 28.4 30.7
Dissolved Oxygen
(mg/L) 4.1 9.6 15.2 4.7 8.0 9.2 1.9 6.8 13.3
pH 6.1 8.3 9.0 6.1 7.8 8.7 6.2 7.8 9.4
Conductivity 66.0 107.5 123.0 83.0 96.0 119.0 70.0 134.5 171.5
Secchi Depth (m) 0.1 0.6 1.8 0.5 0.7 1.1 0.5 0.7 1.0
Turbidity (NTU) 2.2 11.2 20.0 2.5 7.7 19.0 4.2 9.9 32.5
Total Dissolved Solids
(mg/L) 83.0 92.0 134.0 82.0 90.0 110.0 42.0 85.0 101.0
Total Suspended
Solids (mg/L) 1.0 12.0 43.0 6.0 7.0 12.0 4.0 8.6 13.7
Chlorophyll a (gg/1) 12.0 40.5 61.0 16.0 18.0 20.0 7.8 36.0 84.7
Total Phosphorus
(mg/L) 0.1 0.1 0.1 0.0 0.1 0.1 0.1 0.1 0.1
Total Nitrogen (mg/L) 0.5 0.8 2.4 0.4 0.6 0.8 0.5 1.0 1.6
Nitrate-Nitrogen
(mg/L) 0.0 0.3 1.0 0.0 0.2 0.3 0.1 0.1 0.5
Ammonia-Nitrogen
(mg/L) 0.0 0.1 0.7 0.0 0.1 0.3 0.1 0.1 0.3
Total Kjeldahl
Nitrogen (mg/L) 0.4 0.6 1.4 0.2 0.5 0.7 0.5 0.8 1.4
(continued)
Yadkin Project Water Quality Monitoring Study 77 Normandeau Associates
Water Quality
Table 2.5-4. (Continued)
Narrows (Badin)
NCDWQ 1981-86 NCDWQ 1987+ Current Survey
Parameter 5% Median 95% 5% Median 95% 5% Median 95%
Temperature (deg C) 26.0 29.4 33.7 26.7 28.8 30.6 25.6 28.7 30.4
Dissolved Oxygen
(mg/L) 5.5 8.6 12.9 4.2 7.9 10.4 6.1 8.4 11.2
pH 6.8 8.3 9.0 6.4 7.9 9.1 6.9 8.3 8.9
Conductivity 68.0 96.0 178.0 74.0 96.5 108.0 75.0 117.5 139.0
Secchi Depth (m) 0.5 1.0 2.2 0.7 1.2 1.7 0.9 1.3 1.9
Turbidity (NTU) 1.6 3.3 7.0 1.6 3.1 6.6 1.6 3.4 6.9
Total Dissolved Solids
(mg/L) 60.0 87.0 100.0 64.0 76.5 110.0 38.0 68.0 92.0
Total Suspended
Solids (mg/L) 3.0 7.0 11.0 1.0 4.0 10.0 3.0 5.0 6.5
Chlorophyll a (gg/1) 0.5 15.5 46.0 6.0 10.0 31.0 8.4 16.6 31.6
Total Phosphorus
(mg/L) 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.1
Total Nitrogen (mg/L) 0.2 0.6 2.9 0.4 0.4 0.6 0.5 0.7 1.1
Nitrate-Nitrogen
(mg/L) 0.0 0.2 1.4 0.0 0.1 0.3 0.1 0.1 0.4
Ammonia-Nitrogen
(mg/L) 0.0 0.0 1.1 0.0 0.0 0.2 0.1 0.1 0.2
Total Kjeldahl
Nitrogen (mg/L) 0.2 0.4 1.5 0.2 0.3 0.5 0.5 0.6 0.8
Falls
NCDWQ 1981-86 NCDWQ 1987+ Current Survey
Parameter 5% Median 95% 5% Median 95% 5% Median 95%
Temperature (deg C) 25.8 27.6 28.0 26.2 26.6 26.9 23.7 26.4 28.0
Dissolved Oxygen
(mg/L) 3.0 6.8 7.3 3.8 4.8 5.7 3.9 5.5 9.9
pH 6.1 6.7 7.7 6.9 7.2 7.5 6.3 6.9 8.2
Conductivity 69.0 78.0 116.0 77.0 88.0 99.0 68.0 112.0 125.0
Secchi Depth (m) 0.3 1.2 1.7 1.4 1.5 1.6 1.0 1.6 2.0
Turbidity (NTU) 2.2 2.9 13.0 2.1 3.2 4.2 2.0 2.9 13.1
Total Dissolved Solids
(mg/L) 68.0 68.5 110.0 83.0 87.0 91.0 42.0 65.0 92.0
Total Suspended
Solids (mg/L) 3.0 5.0 10.0 1.0 3.0 5.0 3.0 5.0 5.0
Chlorophyll a (gg/1) 5.0 6.0 18.0 4.0 9.0 14.0 5.2 8.0 19.6
Total Phosphorus
(mg/L) 0.0 0.0 0.1 0.0 0.0 0.0 0.0 0.0 0.1
Total Nitrogen (mg/L) 0.4 0.5 0.8 0.5 0.5 0.6 0.5 0.8 1.3
Nitrate-Nitrogen
(mg/L) 0.1 0.3 0.4 0.2 0.2 0.3 0.1 0.2 0.7
Ammonia-Nitrogen
(mg/L) 0.0 0.0 0.3 0.1 0.1 0.1 0.1 0.1 0.4
Total Kjeldahl
Nitrogen (mg/L) 0.2 0.3 0.4 0.3 0.3 0.3 0.5 0.6 0.9
(continued)
Yadkin Project Water Quality Monitoring Study 78 Normandeau Associates
Water Quality
Table 2.5-4. (Continued)
High Rock near mouth of Yadkin River
NCDWQ 1981-86 NCDWQ 1987+ Current Survey
Parameter 5% Median 95% 5% Median 95% 5% Median 95%
Temperature (deg C) 23 26.8 32 22.3 28 29.8 21.8 26.7 31
Dissolved Oxygen
(mg/L) 6.9 7.9 11.3 5.7 7 7.7 6.2 6.9 8.1
pH 6.6 7.4 8.5 6.9 7.5 7.9 6.1 7 7.5
Conductivity 62 90 115 85 109 189 74 135.5 206
Secchi Depth (m) 0.1 0.3 0.6 0.2 0.4 0.5 0.3 0.5 0.7
Turbidity (NTU) 4.6 46 300 18 28 70 16.2 34.3 60.7
Total Dissolved Solids
(mg/L) 99 113 260 98 120 190 64 94.5 780
Total Suspended
Solids (mg/L) 10 30 140 18 24.5 59 14.7 20.5 32.3
Chlorophyll a (ggll) 5 35 43 2 4 8 2 5 16
Total Phosphorus
(mg/L) 0.1 0.1 0.3 0.1 0.2 0.3 0.1 0.2 0.3
Total Nitrogen (mg/L) 0.6 1 1.2 0.8 1.1 1.6 0.8 1.3 2
Nitrate-Nitrogen
(mg/L) 0.1 0.3 0.7 0.6 0.8 1.2 0.6 0.8 1.3
Ammonia-Nitrogen
(mg/L) 0 0.1 0.2 0 0.1 0.3 0.1 0.1 0.1
Total Kjeldahl
Nitrogen (mg/L) 0.3 0.5 0.9 0.1 0.3 0.5 0.5 0.6 0.9
Yadkin Project Water Quality Monitoring Study 79 Normandeau Associates
Water Quality
3.0 IN-DEPTH ANALYSIS OF SPECIFIC WATER QUALITY ISSUES
The following sections address specific issues brought forward through the licensing process. These
issues are evaluated primarily through an in-depth analysis of data collected through the monthly and
continuous tailrace monitoring program. These data were supplemented with targeted field collecting,
where necessary.
3.1 INFLUENCE OF FLOW ON WATER QUALITY
There is the potential for water quality in the Yadkin system to be influenced by flow through the
system. Differences in observed water quality in the reservoirs among years and seasons with
different hydrometeorologic regimes were discussed in Section 2.3. The timescale of reservoir
response to changes in flow is on the order of weeks or months for High Rock and Narrows and days
to weeks for Tuckertown and Narrows due to differences in the flushing rates of these impoundments.
Water quality in the tailraces is influenced by flow on a much shorter time scale. Water in the
tailraces can be exchanged in a matter of minutes if flows through the projects are large. The water
exchange in the tailraces is slower when flows are extremely low during the dry periods typical of late
summer and early fall.
Kendall's tau correlation coefficients were computed to examine potential relationships between
water quality parameters and flow through the dams (Table 3.1-1). Reservoir water quality data from
the surface samples were used in the analysis because surface waters are most visible to reservoir
users and phytoplankton growth (represented by chlorophyll a) is restricted to the surface waters.
Tailrace waters represent a mix of surface and bottom waters due to the intake depths so correlations
from tailraces may or may not be similar to results from upstream reservoirs. The average flow for
the seven days preceding sample collection was used in the correlation because instantaneous and
daily flows can vary considerably and water quality, especially in the reservoirs, is affected by
retention time. Because tailraces flush rapidly and may respond to flow on a more rapid timescale,
correlations based on a daily average flow were also calculated. These results can be found in
Appendix L. Results based on daily averages were similar to correlations calculated using 7 day
average flows although in general, correlations were not as strong and the number of significant
relationships was lower. Results based on these daily average flows are not discussed further.
Reservoir water quality is discussed in more detail in section 2. Dissolved oxygen and temperature
are discussed in this section however; the dynamics of dissolved oxygen and temperature in the
tailraces are evaluated and discussed in more detail in section 3.4 through discussion of the much
more extensive continuous monitoring data set.
Throughout the Yadkin system, higher flows are associated with lower concentrations of alkalinity,
pH, algal biomass (chlorophyll a), total dissolved solids (TDS), biological oxygen demand (BOD),
and total organic carbon. All of these parameters are influenced to some extent by biological
processes. Greater flow reduces retention time in the reservoirs, allowing less time for microbial and
phytoplankton populations to develop. The relationships between flow and BOD, chlorophyll a, and
total organic carbon are strongest in the lower mainstem and arms of High Rock Reservoir and in
Tuckertown Reservoir. Strong relationships between alkalinity, pH and flow exist in all locations.
Total phosphorus (TP) and total suspended solids (TSS) show a weak negative relationship with flow
in High Rock, especially in the arms and generally positive relationships with flow in the lower
reservoirs and tailraces. This may be attributable to a high percentage of inorganic solids and
Yadkin Project Water Quality Monitoring Study 80 Normandeau Associates

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Table 3.1-1. Kendall's tau correlation coefficients of weekly average flow versus water quality parameters in the reservoirs and
tailraces.l
Reservoirs Tailraces

Parameter Upper High
Rock Mainstem Lower High Rock
Mainstem High Rock
Arms
Tuckertown
Narrows
Falls
High Rock
Tuckertown
Narrows
Falls
Alkalinity -0.4020 -0.4095 -0.2582 -0.4694 -0.4574 -0.4612 -0.3876 -0.4573 -0.4536 -0.5096
BOD 0.0222 -0.2517 -0.2401 -0.2807 -0.0646 0.0462 -0.2265 -0.3034 0.0550 -0.0309
Chlorophyll a -0.0561 -0.2375 -0.2512 -0.3919 -0.0929 -0.2289 -0.3877 -0.3884 -0.1123 -0.0791
Secchi Depth -0.0244 0.0468 0.2250 -0.1226 -0.1697 -0.4319 -0.1576 -0.1691 -0.3645 NA
Total Organic Carbon -0.1565 -0.2217 -0.0535 -0.1334 0.0346 0.0454 -0.1900 -0.1335 0.1355 0.0434
Ammonia -0.1071 -0.2431 -0.1391 0.0993 0.0849 0.0760 -0.1557 -0.1769 0.1033 0.1066
Nitrate -0.1171 0.1143 0.1140 0.3279 0.3634 0.4224 0.1478 0.2529 0.3920 0.4121
Total kjeldahl Nitrogen -0.0084 -0.2040 -0.2261 -0.0766 0.0302 -0.0083 -0.2012 -0.1907 0.0300 -0.1128
Total Nitrogen -0.0381 -0.0979 -0.1370 0.1413 0.2351 0.2182 -0.0840 0.0130 0.2320 0.1064
Total Phosphorus -0.2410 -0.1418 -0.2101 0.0191 0.2366 0.2752 -0.1065 0.0370 0.3209 0.2242
Total Dissolved Solids -0.1902 -0.2958 -0.2267 -0.1987 -0.2448 -0.2312 -0.2572 -0.2884 -0.2059 -0.2551
Total Suspended Solids -0.0139 -0.0736 -0.2454 0.0812 0.1459 0.2115 0.0258 0.0267 0.2292 0.2298
Turbidity 0.0446 0.0635 -0.1429 0.2982 0.2804 0.5188 0.2806 0.3903 0.4852 0.5554
Temperature -0.1294 -0.1325 -0.0941 -0.2151 -0.1851 -0.2337 -0.1819 -0.2175 -0.2103 -0.2098
Dissolved Oxygen 0.0894 0.0817 0.0190 -0.0528 0.2337 0.1368 0.0849 0.2560 0.2169 0.2221
pH -0.4097 -0.2471 -0.2419 -0.3971 -0.1666 -0.3546 -0.3833 -0.2253 -0.2510 -0.3459
1 Significant correlations at 95% level (p <_.05) are noted in bold type.
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Water Quality
phosphorus represented in High Rock total suspended solids concentrations. Many of these inorganic
solids and associated phosphorus settle in High Rock (discussed further in Section 3.5) increasing the
relative importance of organic solids and phosphorus associated with algae lower in the system. Algae
often reach high concentrations during low flow periods throughout the system, but reperesent a
larger percentage of total suspended solids lower in the system.
In general, nitrogen concentrations are poorly correlated with flow. With the exception of nitrate, the
correlation coefficients are very low and significant correlations do not reveal any consistent trends.
Nitrate concentrations tend to increase with greater flows, probably the outcome of reduced time for
microbial populations to exploit the nutrient. Also, nitrate concentrations are lowest during the
summer, when flows tend to be lower. Nitrate concentrations in the upper mainstem of High Rock
Reservoir, where algal biomass is typically low, are negatively correlated with flow which suggests
that dilution during high flow periods has a greater effect than algal assimilation. Greater flows are
associated with greater turbidity, especially downstream of High Rock Dam. Temperature is also
slightly cooler during high flow periods.
Significant correlations (14 of 16 parameters) were most frequently observed in the arms and lower
mainstem of High Rock Reservoir. High Rock Reservoir is the largest reservoir and has the longest
retention time. It is also the location of intense biological activity as the environment transitions from
a river to a reservoir environment. There were somewhat fewer significant correlations (9-11 of 16
parameters) at all other stations except Upper High Rock (6 of 16 parameters). Upper High Rock
water quality may be more closely related to inflow from the Yadkin and South Yadkin rivers than
flow through High Rock Dam.
Flow through High Rock Reservoir and the entire system is primarily controlled by precipitation and
climate particularly during periods of normal to high precipitation in the watershed however daily
flow through each of the dams is controlled by scheduled releases during periods of low flow. During
the five years of this study, drought conditions were extreme in 2002 resulting in near-record low
flows in the Yadkin River basin. The drought year was followed by an extremely wet year and flow
was at high levels throughout 2003. This provides the opportunity to examine the effects of extreme
flow conditions on water quality in the reservoirs. Flows differed by about an order of magnitude
between 2002 and 2003 (Figure 1.0-1) with flows in the other years at intermediate levels.
During the drought year, High Rock and Tuckertown dams were essentially shut down during the
summer and the water pooled behind the dams dropped to record low levels. Surface temperatures
were slightly warmer in the summer of 2002 and dissolved oxygen levels in High Rock were
extremely high indicating intense algal photosynthesis. Concentrations of chlorophyll a, total
dissolved solids, total organic carbon and total Kjeldahl nitrogen were greater than normal in High
Rock reservoir, suggesting that intense algal productivity was occurring in the pooled slightly warmer
waters impounded above High Rock Reservoir. Higher levels of chlorophyll a, total dissolved solids
and total organic carbon occurred in the downstream reservoirs as well. Nitrate concentrations in
High Rock reservoir were lower than normal during the drought year of 2002, probably due to the
greater retention time allowing algae more time to exploit the nutrients.
Concentrations of most parameters were lower during 2003, the high flow year. Chlorophyll a and
total dissolved solids concentrations were much lower in 2003. The high flows result in much shorter
retention time in the reservoirs and algal populations likely did not have time to develop to the
concentrations observed in the other years. Nitrate concentrations were greater in 2003 because of the
Yadkin Project Water Quality Monitoring Study 82 Normandeau Associates
Water Quality
lower concentrations of algae. The increase in precipitation appears to have had a diluting effect in
the reservoirs. Total dissolved solids concentrations were much lower during the high flow year. To a
lesser extent, concentrations of most of the other parameters were also lower in 2003. The high flow
rates of 2003 had great effects on dissolved oxygen concentrations. In all four reservoirs, well-
oxygenated waters extended to greater depths and persisted longer than the previous years. Oxygen
depletion in the bottom was limited to July and August and anoxia was much more limited than
observed in previous years.
3.2 INFLUENCE OF RESERVOIR WATER LEVELS ON WATER QUALITY
Water levels in the Yadkin system vary seasonally. During periods of normal precipitation and flows,
High Rock is operated as a seasonal storage facility. Typically, this means that High Rock is drawn
down to its lowest levels during the fall and winter in anticipation of late winter and spring storms
and high flow events. During periods of extreme drought however, High Rock and Narrows
reservoirs can experience substantial drawdown in the summer, as occurred in 2002. Tuckertown and
Falls reservoirs maintain relatively stable pools most of the time. Water levels in the four
impoundments over the water quality monitoring study period are presented in Figures 1.0-2 through
1.0-5. Differences in water quality in the reservoirs among years and seasons with different
hydrometeorologic regimes were discussed in Section 2.3. The influence of water level changes on
tailrace dissolved oxygen and temperature resources is discussed further in Section 3.4.
The effect of the reservoir water level on surface water quality in each respective reservoir was
evaluated using the monthly surface water quality data collected from 1999 through 2003 and
reservoir water level data obtained from Yadkin APGI. The influence of reservoir water level on
water quality was evaluated by Kendall Tau correlation analysis. Tailrace water quality was
correlated with the water level in the upstream reservoir. Correlation coefficients (p<0.05, 95%
significance level) of water level versus 10 water quality parameters are presented in Table 3.2-1.
Dissolved oxygen and temperature are discussed in this section and the dynamics of dissolved oxygen
and temperature in the tailraces are evaluated and discussed in more detail in Section 2.4 using the
much more extensive continuous monitoring data set. The influence of water level on oxygen
distribution and thermal stratification was discussed in more detail in Section 2.3.
Surface water quality is poorly correlated with lake level. Most correlation coefficients are low
indicating that poor, if any, relationships exist between lake level and water quality. Significant
correlations are absent in Falls Reservoir and rare in Tuckertown, the two reservoirs where lake level
remains constant. Significant correlations are not observed for total organic carbon or ammonia in any
of the reservoirs. Correlations of the other parameters with lake level, even if significant, are
generally poor in High Rock and Narrows reservoirs. The strongest associations are for total
phosphorus and total dissolved solids in High Rock Reservoir and for nitrate and temperature in
Narrows Reservoir. In general, coefficients were negative indicating that at lower lake levels,
concentrations are higher, but these higher values are likely an effect caused by seasonality as the
extreme low lake levels occurred in summer in High Rock Reservoir and in summer and fall in
Narrows Reservoir.
The correlation of water quality of the tailraces with the lake level of the upstream reservoir is also
poor. In High Rock Reservoir, low lake levels were associated with greater levels of biological
Yadkin Project Water Quality Monitoring Study 83 Normandeau Associates

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Table 3.2-1. Correlation coefficients (p <0.05, 95% significance) of water level versus surface water quality parameters throughout the
Yadkin system. Significant correlations are noted in bold type.
Reservoirs Tailraces

Parameter Lower HR
Mainstem Upper HR
Mainstem HR
Arms
Tuckertown
Narrows
Falls
High Rock
Tuckertown
Narrows
Falls
Biochemical Oxygen Demand -0.1776 0.1001 -0.2677 -0.0138 -0.0097 -0.0820 -0.3005 0.0117 0.1420 0.0844
Chlorophyll a -0.1886 0.0682 -0.2563 -0.0182 -0.2519 -0.1250 -0.3728 0.0690 -0.2388 0.0028
Ammonia -0.0872 -0.0280 -0.1734 0.0244 0.1032 0.0760 0.0083 -0.1561 0.0077 0.2101
Nitrate 0.0088 -0.2250 0.0655 0.0974 0.5391 0.0915 -0.0108 0.2014 0.4900 0.0862
Total Dissolved Solids -0.3652 -0.2980 -0.4329 0.0615 -0.0485 -0.1795 -0.3199 0.0707 -0.0482 -0.2714
Total Organic Carbon -0.0665 -0.0170 -0.0703 -0.0584 0.0144 0.0950 -0.1476 -0.0294 0.1402 0.0929
Total Phosphorus -0.3079 -0.3131 -0.3817 0.1374 0.2437 0.1256 -0.1508 -0.0284 0.1957 0.0893
Total Suspended Solids -0.1649 -0.0520 -0.3939 0.1199 0.1732 0.0900 -0.0773 0.0432 0.3660 0.0530
Dissolved Oxygen 0.0217 -0.0147 0.0070 0.2014 0.3099 0.0788 -0.0148 0.1698 0.4274 0.0653
Temperature 0.0276 0.0222 0.0627 -0.1731 -0.3948 -0.0492 -0.0270 -0.1838 -0.4532 -0.0254

"It
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Water Quality
oxygen demand, chlorophyll a and total dissolved solids; parameters that reached high concentrations
during the extreme low lake levels experienced during the drought year 2002. At Narrows tailrace,
most parameters are correlated with the level of Narrows Reservoir. The strongest correlations
occurred between lake level and temperature, dissolved oxygen and nitrate, which are all highly
seasonal parameters. Since low lake levels ocuur in the summer and fall, temperature are greater
during periods of low lake level. Conversely, both dissolved oxygen and nitrate are seasonally at low
levels in summer and are positively correlated with lake level. Correlation coefficients in Tuckertown
and Falls Reservoirs were all low indicating no effects of lake level on water quality.
In general, reservoir water levels probably have little or no direct effect on water quality. Under
normal operations in typical hydrologic years, reservoir levels are lowest in the late fall and winter.
During periods of drought, such as that experienced in 2002, reservoir levels were at their lowest in
the summer in High Rock and Narrows reservoirs. In this year, changes in water quality that appear
related to reservoir level are more likely related to seasonal effects caused by climate and biological
activity or flow through the reservoirs as discussed in Section 3.1.
3.3 INFLUENCE OF OPERATIONS ON DISSOLVED OXYGEN IN TAILWATERS
Continuous dissolved oxygen and temperature data from all four tailwaters have been discussed in
detail in Section 2.4. This section presents a detailed look at tailrace conditions under specific
controlled operating conditions.
Modifications to Narrows Unit 4 turbine, including the addition of two air injection valves, were
completed in early 2001. Operation of these valves was intended to introduce air into the flow during
Unit 4 generation to increase dissolved oxygen concentrations downstream. In August 2001,
following the installation of the air valves, a series of tests were performed to understand the effect on
downstream dissolved oxygen of operation of the new air valves under various generation regimes. A
second round of operational testing was performed in 2004 to supplement the data gathered in 2001.
3.3.1 August 2001 Operations Testing
The 2001 testing focused on the Narrows tailwater and took place over a two-day period in August,
2001 recording dissolved oxygen concentrations under various operating regimes, with and without
Unit 4 air valve operation. Results of this survey were reported on in detail in an earlier study report
submitted to FERC (NAI, 2002). A summary description of the various operating regimes and the
observations recorded during each survey are presented in Table 3.3-1. The actual dissolved oxygen
readings taken at 15-minute intervals in the Narrows tailwater are presented in Figure 3.3-1 and the
Narrows station flow and generation data are presented in Figures 3.3-2 and 3.3-3, respectively. In
addition, to provide an indication of the conditions upstream of Narrows during that same time frame,
dissolved oxygen concentrations at selected locations in the Yadkin River on August 14 and 15, 2001
are presented in Table 3.3-2.
A review of the field test data indicate that operational changes, including use of the air valves, do
affect dissolved oxygen in the Narrows tailwater. Figure 3.3-1 illustrates the effect that both level of
operation and aeration have on the dissolved oxygen concentration in the tailwater and reveals the
following trends:
Yadkin Project Water Quality Monitoring Study 85 Normandeau Associates
Water Quality
Table 3.3-1. Summaries of Dissolved Oxygen Observations During August, 2001 Testing
Survey Operating Regime Observations
1 Unit 4 at 22 MW (1700 cfs), and
' With the start up of Unit 4 at full load, dissolved
no air in
ection oxygen drops sharply about 5 m /l
2 Unit 4 at 28 MW (2300 cfs) and 1 With the opening of one air valve, dissolved
air valve open oxygen increases 3 mg/l
3 Unit 4 at 22 MW (1700 cfs) and 2 With the opening of a second air valve, dissolved
air valves open oxygen increases an additional 0.5 mg/1.
4 4 units at 0 MW (0 cfs) and no With the shutdown of all units, dissolved oxygen
aeration decreases 2 m /l over the course of 2 hours.
4 units at 89 MW (7000 cfs) and With the startup of 4 units at full load, the
no aeration dissolved oxygen drops sharply about 2 mg/1.
5 During the one hour following the sharp drop the
dissolved oxygen levels stabilize and there is little
further change.
6 4 units at 0 MW and no aeration - The effect of the Survey 6 operating regime is
units wheeling, no indication of masked by the antecedent operating regime. With
flow rate (see Note) flow release from all units and no generation the
dissolved oxygen appears to rise from 1.5 to 7.5
mg/l over a two hour period. However, two hours
prior to Survey 6, the plant was running Units 1
and 2 at full load, causing a sharp reduction in
dissolved oxygen to 1.5 mg/1. Then, one hour
before Survey 6, Units 1 and 2 are shut down,
causing a sharp rise in dissolved oxygen such that
the dissolved oxygen has increased to almost 5
mg/l by the start of Survey 6.
4 units at 86 MW (6865 cfs) and When the 2 air valves are opened during
7 2 air valves open generation at full load, the dissolved oxygen rises
1.5 mg/1.
Note: The reported operating condition during Survey 6, occurring from 1130 through 1230 -that is, flow released through
all four turbines with no generation- does not appear to correspond with either the power generation data or the flow data
recorded in the Yadkin Flow Extractor. As seen in Figures 6 and 7, both flow and generation are recorded during hour 1100
on Aug 17. However, the non-zero values are an indication that generation and corresponding flow occurred for a short time
at the beginning of the hour. Shortly after the hour, the generator was tripped and the turbine turned or "wheeled", releasing
water without generating electricity. During hour 1200, the continuation of Survey 6, neither flow nor generation are
recorded. Because Yadkin determines turbine discharge by measuring generation and converting to flow, the Flow
Extractor would record zero turbine flow under this operating condition.
Yadkin Project Water Quality Monitoring Study 86 Normandeau Associates
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Water Quality
Table 3.3-2. Dissolved Oxygen Concentrations at Selected Locations Upstream of Narrows
During the Time Frame of the August 2001 Testing
Dissolved
Oxygen Dissolved Oxygen
Station Date Location Depth Concentration
Hl 8/15/2001 Yadkin River at the upstream end of 3 m 6.3 mg/1
High Rock Reservoir
N4 8/14/2001 Narrows Reservoir upstream of Dam 15 m 0.2 mg/1
Fl 8/14/2001 Narrows Dam 3 m 6.0 m /1
g
Tailwater
When one of any of the four units is operating at very low levels (I to 10 MW; <1000
cfs), dissolved oxygen levels increase significantly.
This trend is apparent at 0200 on Aug 17 when the units are running at 2 MW, and the
dissolved oxygen increases about 4 mg/l from 1.5 mg/1 to 5.5 mg/l over a 2-hr period. A
discussion with Ken Hunsucker, APGI Operations staff, indicated that each Narrows
turbine includes the provision of air valves on the head cover to admit air into the turbine
on startup and shutdown to protect the turbine from transient pressures. These air valves,
separate from the new air injection valves on Unit 4, are mechanically linked to the
wicket gate operating ring and are designed to open at 20% gate and close at 35% gate.
At low loads the Narrows turbines are likely operating in this range of wicket gate
opening and the additional air is reflected in the dissolved oxygen downstream. The
introduction of air causes a substantial loss in unit efficiency. Moreover, the units are not
designed to operate at this load on a continuous basis, and to do so would significantly
damage the units.
When power generation is at high levels (20 to 90 MW, approx. 1500-7000 cfs),
dissolved oxygen levels fall sharply.
A comparison of dissolved oxygen under various operating regimes shows that when any
number of units from one to four are generating at full power, the dissolved oxygen
concentrations decrease significantly. For example, upon running all units at 80 to 85
MW from hours 1200 to 2000 on Aug 16, the dissolved oxygen drops 2 mg/l from 4.7 to
2.7 mg/l.
When air valves are opened at high generation levels, the dissolved oxygen
concentration increases 2-3 mg/l.
The effect of operation of the air valves is illustrated during Survey 1 through Survey 3.
When only Unit 4 is operating (approx. 2000 cfs) dissolved oxygen concentrations drop
sharply about 5 mg/1 with no aeration, increase 3 mg/1 upon opening a single air valve
and increase an additional 0.5 mg/l for a total improvement of 3.5 mg/l with both air
valves open. The majority of the total dissolved oxygen increase is provided upon
opening the first air valve, with a lesser benefit provided by opening the second air valve.
• After making an operational change, there is a time lag before dissolved oxygen
changes are observed in the tailwater.
This time lag is illustrated during Survey 1, where Unit 4 is started (at 22 MW and 1700
cfs) at 0600 on August 16 and the initial effect on dissolved oxygen is not observed until
about 0630, indicating a time lag of about 30 minutes. Similarly, just after the
Yadkin Project Water Quality Monitoring Study 90 Normandeau Associates
Water Quality
completion of Survey 4, all units are started up (at 84 MW and 6700 cfs) and the initial
effect on dissolved oxygen is not observed until about 15 minutes later. Time lag appears
to be a function of total flow rate, with a shorter lag as flow increases.
In addition to this time lag, the total time required for the downstream dissolved oxygen
to reach a new equilibrium following each operational change appears to be longer
than one hour. The one-hour duration for these tests was too short to clearly show the
effects of the operating configurations on tailwater dissolved oxygen.
Referring again to Figure 3.3-1, an example of this trend is seen when, after starting Unit
4 at 0600 on Aug 16, the dissolved oxygen drops sharply and does not have time to level
out before one air valve is opened at 0700, opening one air valve. While the general
direction of the response to each operational change was evident, none of the seven
surveys performed allowed sufficient time for dissolved oxygen to reach a new
equilibrium, and the total effect of the various operations was not clearly observed.
Based upon the results of the August 2001 testing, the normal operating policy at Narrows in 2002,
2003, and 2004 was revised to operate with both air valves open whenever Unit 4 is operated between
May and November in an attempt to increase dissolved oxygen downstream.
3.3.2 August 2004 Operations Testing
Based on the data from the 2001 testing at Narrows and discussions with the Water Quality IAG,
there were several areas in which further investigation was warranted, and some of these areas were
the subject of the additional operations testing performed in 2004. First, at the May 4, 2004 meeting,
the WQ IAG suggested some additional investigation of the aeration capability provided by the Unit 4
air injection valves to better understand the effect of air injection through Unit 4 on Narrows tailwater
dissolved oxygen concentrations, particularly under various unit operating configurations. Second,
through discussions with the IAG, it became clear that it would be useful to understand the effect on
dissolved oxygen concentrations in the Falls tailwater given an increase in dissolved oxygen
concentrations in the Narrows tailwater. Similarly, the relationship between dissolved oxygen in the
High Rock tailwater and dissolved oxygen in the Tuckertown tailwater were also deemed to be worth
investigating.
The objectives of the additional operations testing were:
To further evaluate the effectiveness of the air injection valves at Narrows Unit 4 to increase
tailwater dissolved oxygen levels;
• To determine how increases in dissolved oxygen concentrations in the Narrows tailwater
impacts the dissolved oxygen concentrations in the Falls tailwater; and
• To determine if an increase in dissolved oxygen concentrations in the High Rock tailwater
impacts the dissolved oxygen concentrations in the Tuckertown tailwater.
The target timing for the 2004 testing was during a period of low river flow coupled with high water
temperatures, conditions that have historically resulted in low tailwater dissolved oxygen
concentrations. In the Yadkin system, these conditions are typically encountered between August 1
and September 30. Preliminary testing to confirm travel times from High Rock to Tuckertown and
from Narrows to Falls was scheduled for August 5 through 8, 2004; and the final testing was
scheduled to be completed on September 8, 9 and 10, 2004. The preliminary testing was completed
as scheduled, with dissolved oxygen conditions and water availability allowing Yadkin to perform the
desired testing. The occurrence of high inflows due to hurricanes in the region, however, delayed the
Yadkin Project Water Quality Monitoring Study 91 Normandeau Associates
Water Quality
final testing. When the inflows finally receded enough to safely perform the tests, the reservoir
dissolved oxygen had increased thereby increasing the tailrace concentrations and the second test was
cancelled. As a result, the data presented in this report are those collected during the August
preliminary tests.
3.3.2.1 Methodology for 2004 Survey
The continuous monitors placed in each of the tailwaters was the primary point of measurement of
tailwater conditions. The locations of these monitors are presented in Figures 2.4-6 through 2.4-9.
During each test, dissolved oxygen and temperature readings were continuously logged and reviewed
in the field in "real time". Dissolved oxygen concentrations were recorded throughout the test period
or until equilibrium in dissolved oxygen concentrations was reached. Equilibrium was considered to
have been reached when the dissolved oxygen concentrations of three successive readings were
within 0.5 mg/l of each other. Each reading for this test was a 15-minute average concentration.
Short term variations of less than 0.5 mg/l are typical in the tailwaters due to water turbulence. Once
equilibrium was reached in the tailwater under each operating scenario, real time monitoring
continued for at least 2 hours. At the end of each day's testing, all data were downloaded and
evaluated to help guide the following day's testing and shed light on the persistence of changes in
tailwater dissolved oxygen concentrations downstream. The meters were serviced and calibrated
prior to and after testing and were checked for calibration with an independent meter at the beginning
and end of each test scenario and each time the data were downloaded.
Similar data were required for all dissolved oxygen testing. The data type and source are as follows:
• Dissolved Oxygen and Temperature - The existing continuous dissolved oxygen/temperature
monitors in the High Rock, Tuckertown, Narrows and Falls tailwaters were used to measure
dissolved oxygen and water temperature.
• Turbine Power Output - The turbine power output for all powerhouses was measured using
existing metering equipment and recorded in the APGI Operating Center.
Turbine Discharge - Water flow through all turbines was calculated from power output.
Narrows
At Narrows, a follow-up to the 2001 dissolved oxygen testing was performed to meet the first and
second study objectives outlined above. The testing was designed to use existing equipment to
temporarily increase Narrows tailwater dissolved oxygen to the extent possible, and to investigate
how and to what degree this translated into dissolved oxygen increases downstream through the Falls
tailwater. To do this, the turbines at Narrows powerhouse were used to introduce air into the water
stream in the draft tubes through two sources. The first source is the aeration system installed on the
draft tube at Narrows Unit 4 as part of the turbine refurbishment and upgrade. In addition, the
Narrows Units 1 through 3 naturally aspirate air through the water wheel cone in the range of 20 to 35
percent wicket gate opening (approximately 1000 cfs per unit). Valves open while the turbine is
operating at this small wicket gate setting to allow air to enter the draft tube to stabilize the turbulence
that is inherent in this operating range.2
z This air serves to reduce vibration and damage to the equipment during loading and unloading of the
generating unit. While this mode of operation allowed Yadkin to conduct a test on a short-term basis, it is not
suitable for continuous operation due to the very low efficiency and the potential for damage to the turbines.
Yadkin Project Water Quality Monitoring Study 92 Normandeau Associates
Water Quality
The Narrows turbines were started individually beginning with Unit 4 at best efficiency with both air
valves closed. Next, a single air valve was opened, and then the second air valve was opened. The
other three turbines were started sequentially and operated at 30% wicket gate to allow air to enter the
draft tube. Next, each of Units 1 through 3 were brought from 30% gate to best efficiency one at a
time so that the incremental impact of the configuration changes could be observed. To allow the
tailwater dissolved oxygen concentrations to reach equilibrium for each operating configuration, the
duration of each test was a minimum of 3 hours and the various test sequences were run on successive
days.
The operation of the Narrows turbines in each test mode was continued for a sufficient length of time
to evaluate the effect of increased dissolved oxygen at Narrows on dissolved oxygen in the Falls
tailwater. The expected travel time of the oxygenated water from Narrows to Falls was estimated at
about 3 hours based upon discharge volume and reservoir storage prior to the survey and confirmed
by observations during the testing. This expected travel time is lower than the annual average (1.7
hours) presented earlier in this report.. The dissolved oxygen in the Falls tailwater was monitored
using the currently installed continuous dissolved oxygen monitors throughout the testing at Narrows.
Falls
The turbines at Falls powerhouse were started and operated at power output necessary to pass the
flow coming from Narrows powerhouse with a minimum of reservoir fluctuation, mimicking typical
operation for Yadkin.
High Rock and Tuckertown
A similar set of information is desired at High Rock and Tuckertown to address the third objective of
this study. Though no air injection system is currently installed at High Rock, as part of this study,
Yadkin used existing piping and valves on the three High Rock units to inject air through the bearing
riser to the top of the runner, on a short term basis, as a way of increasing High Rock tailwater
dissolved oxygen concentrations. While this method of injecting air can only be used for short term
test purposes due to the low efficiency and potential damage to the turbine, it was used to evaluate on
an order-of magnitude basis, whether increasing High Rock dissolved oxygen concentrations results
in a measurable improvement in dissolved oxygen concentrations in the Tuckertown tailwater. The
testing program below High Rock and Tuckertown was conducted in a manner similar to that
proposed for Narrows and Falls as described above.
During this test, the intent was to start Tuckertown turbines and operate at power output necessary to
pass the flow coming from High Rock powerhouse with a minimum of reservoir fluctuation.
However, power generation needs required that Tuckertown be operated somewhat differently than
planned and the units were operated in more of a peaking mode.
3.3.2.2 Results for 2004 Survey
The results of the 2004 testing are presented and discussed for each development. Results are
presented in Table 3.3-3 and in Figures 3.3-4 through 3.3-6. The dissolved oxygen and temperature
data and the discharge data are presented in separate figures for clarity, and the figures are presented
one above the other for comparison.
Yadkin Project Water Quality Monitoring Study 93 Normandeau Associates
Water Quality
Narrows
The 2004 Narrows/Falls testing took place over a four-day period in August, recording dissolved
oxygen concentrations under various operating regimes, with and without air valve operation. A
description of the various operating regimes, from lowest to highest discharge, and the observations
recorded during each survey are presented in Table 3.3-3. The actual dissolved oxygen readings
taken at 15-minute intervals in the Narrows tailwater are presented in Figure 3.3-4, the Narrows
discharge data are presented in Figure 3.3-5 and a profile of the intake dissolved oxygen is presented
in Figure 3.3-6. The Narrows data show that:
Table 3.3-3. August 2004 Operations Testing - Narrows Configuration and Results.
Dissolved
Total Oxygen Dissolved
Discharge Change Oxygen
Test Unit Configuration cfs m /l Mg/1
Baseline U4 @ 20% gate or 4 MW 350 5.25
Test 6 U4 @ BE or 28 MW no air 2240 -2.00 3.25
Test 7 U4 @ BE or 28 MW 1 air vlv 2240 1.75 5.00
Test 8 U4 @ BE or 28 MW 2 air vlv 2240 0.25 5.25
U4 @ BE or 27 MW 2 air vlv
Test 9 2580
Ul @ 30% gate or 5 MW
U4 @ BE or 25 MW 2 air vlv
Test 4 3420
Ul, U2 @ 30% gate or 8,8 MW 0.25 5.50
U4 @ BE or 25 MW 2 air vlv
Test 5 Ul, U2, 4625
U3 @ 30% gate or 8, 8, 7 MW
U4 @ BE or 23 MW 2 air vlv
Test 1 Ul @ BE or 23 MW 4885 -1.50 4.00
333U2, U3 @ 30% gate or 8,8 MW
U4 @ BE or 25 MW 2 air vlv
Test 2 Ul, U2 @ BE or 24,24 MW 6440 -0.50 3.50
U3 @ 30% gate or 8 MW
U4 @ BE or 29 MW 2 air vlv
Test 3 U1, U2, 26, 28, 9170 0.00 3.50
U3 @ BE or 28 MW
Yadkin Project Water Quality Monitoring Study 94 Normandeau Associates
Water Quality
Narrows Tailwater DO
87
85
83
m 81
m
m
rn
79
ai
3
m 77
`m
a
E
m
~ 75
`m
m
3
'm 73
71
69
67

N

F N
N

F M
N

F ?
N

F N
N

F f0
?

~ r
N

F ?
N
d
? 01
N

F

--- ---
?J
--- ---
II
- ---- --
J

-----
--- ----
---
-------

-
----
----
----

--
----
----
----

-
--------
- -----------

---------
----------
----------
----------

---
-
----
----
----

---
---
----
----
----
8/5/2004 000 8/6/2004 000 8/7/2004 000 8/8/2004 000
NA Temp NA DO - - Target DO
Figure 3.3-4. Narrows 2004 Operations Test - dissolved oxygen and Temperature
Narrows Releases
10000
9000
8000
7000
T
6000
ai
rn
`m
5000
2.
4000
O
H
3000
2000
1000
0
8/5/04 0:00 8/6/04 0:00 8/7/04 0:00
ONA Tot Plant Discharge
Figure 3.3-5. Narrows 2004 Operations Test - Discharge
8/8/04 0:00
10
9
8
7
6 rn
E
O
5 ?
`m
m
3
4 F
3
2
1
0
8/9/2004 000
8/9/04 0:00
Yadkin Project Water Quality Monitoring Study 95 Normandeau Associates
Water Quality
Narrows DO Profile at Intake
550.00
530.00
510.00
490.00
Q 470.00
450.00
.c w 430.00
410.00
390.00
370.00
350.00
0.00
2.00 4.00 6.00 8.00 10.00 12.00
DO, ppm
8/5/2004 @ 9 AM -Intake Top - -CL -Intake Bottom
Figure 3.3-6. Narrows 2004 Operations Test - Intake dissolved oxygen Profile
Baseline - At the start of the testing, Unit 4 was running at 3-4 MW, the reservoir dissolved
oxygen was about I mg/l at the intake, and the tailwater dissolved oxygen was 5 to 6 mg/1.
The higher tailwater dissolved oxygen could be because, 1) the volume of low dissolved
oxygen water introduced into the tailwater under this operating condition is so small that it
has negligible impact on the fully-mixed tailwater dissolved oxygen; 2) the unit is pulling the
higher dissolved oxygen surface water into the intake; or 3) running a unit at 3-4 MW adds
substantial dissolved oxygen to the discharge. Tests 9, 4 and 5 further investigate the effect
on tailwater dissolved oxygen of operation at low loads. The results lead to the conclusion
that running a unit at 3-4 MW does not significantly improve the tailwater dissolved oxygen
under higher flow configurations.
• Test 6 - Starting Unit 4 at best efficiency with no air valves reduces dissolved oxygen by 2
mg/1.
• Tests 7 and 8 - With only Unit 4 on-line, opening the two air injection valves increased the
dissolved oxygen about 2 mg/l with about 88 percent of the increase provided by the first
valve, and an additional 12 percent increase from the second valve.
• Tests 9, 4 and 5 - The sequential addition of Units 1, 2 and 3 at 30 percent gate improves the
dissolved oxygen only slightly. The operation of Units 1, 2 and 3 at 30 percent gate resulted
in a discharge plume white with air bubbles, but the dissolved oxygen measured in the
tailwater increased only 0.25 mg/1.
• Tests 1, 2 and 3 - The sequential ramp up of Units 1, 2 and 3 from 30 percent gate to best
efficiency reduces the dissolved oxygen 2 mg/1.
Yadkin Project Water Quality Monitoring Study 96 Normandeau Associates
Water Quality
Falls
The actual dissolved oxygen readings taken at 15-minute intervals in the Falls tailwater are presented
in Figure 3.3-7, the Falls discharge data are presented in Figure 3.3-8 and a profile of the intake
dissolved oxygen is presented in Figure 3.3-9. In general, the response in the Falls tailwater DO to
changes in the Narrows tailwater DO is similar though of lesser magnitude. A low discharge at
Narrows, such as that during single unit operation, has a slight effect in the Falls tailwater, and the
effect increases as the Narrows discharge increases. The Falls data show that:
• Baseline - At the start of the testing, dissolved oxygen at both the Falls reservoir intake and
tailwater was 6 to 7 mg/1.
• Tests 6, 7 and 8 - Tests 6, 7 and 8 are all single unit operation at Narrows. The 2 mg/l drop
in dissolved oxygen in the Narrows tailwater that resulted from starting Unit 4 at best
efficiency with no air valves, followed by the 2 mg/1 increase upon opening the two air valves
has a similar though very small, if any, impact on Falls tailwater dissolved oxygen levels.
• Test 9 - The addition of Unit I at 30 percent gate at Narrows does not have any measurable
effect in either the Narrows or the Falls tailwater.
• Tests 4 and 5 - The sequential addition of Units 2 and 3 at 30 percent gate at Narrows does
not have a measurable effect at Narrows. However, the Falls tailwater dissolved oxygen
drops I mg/1 from 6 to 5 mg/l during Tests 4 and 5. This I mg/l drop in dissolved oxygen at
Falls may be due to lower dissolved oxygen water released from Narrows the day before,
residing in Falls reservoir during the overnight Falls shutdown, then being released on Falls at
the start up for Test 4.
• Tests 1, 2 and 3 - Tests 1, 2 and 3 are two-, three- and four-unit operation at Narrows,
respectively. Changes in the Narrows tailwater dissolved oxygen under these higher flow
releases are more strongly reflected in the Falls tailwater. The 2 mg/l drop in dissolved
oxygen at Narrows that results from the sequential ramp up of Units 1, 2 and 3 from 30
percent gate to best efficiency results in a I to 2 mg/l drop in the Falls tailwater dissolved
oxygen.
High Rock and Tuckertown
The 2004 High Rock/Tuckertown testing took place over a three-day period, recording dissolved
oxygen concentrations under a single operating configuration with air injection into all three High
Rock units. Valves on all three High Rock units were opened at IPM on August 4 and the High Rock
units were run in this configuration for a period of 44 hrs, the estimated time required for the water to
travel to Tuckertown Dam. The units were set at 50% gate, the setting that provided the maximum air
intake. The actual dissolved oxygen readings taken at 15-minute intervals in the High Rock tailwater
are presented in Figure 3.3-10. The High Rock discharge data are presented in Figure 3.3-11 and a
profile of the intake dissolved oxygen is presented in Figure 3.3-12. The High Rock data show that:
• The reservoir dissolved oxygen at the start of the test, as shown in Figure 3.3-12, varies from
I to 9 mg/1 from the bottom to the top of the intake and averages about 4 mg/1. At the end of
the test, Figure 3.3-13, the reservoir dissolved oxygen profile at the intake has become a more
uniform 5.5 mg/l across the intake.
Because no response is seen upon opening the valves at the beginning of the test, this method of air
injection does not result in a measurable increase in the High Rock tailwater dissolved oxygen.
Though the dissolved oxygen increases over the three-day test period, it is apparently the result of
improved reservoir dissolved oxygen and diurnal cycles in the dissolved oxygen and temperature
rather than air introduced by the unit valves.
Yadkin Project Water Quality Monitoring Study 97 Normandeau Associates
Water Quality
Falls Tailwater DO
87
85
83
aN 81
d
a
d
79 -
ai
77
a
d
? 75 -
d
io
3 73 --------
71
69
67

F N

F M

F ?

F N
N
N
F f0

F r

F W

F ?

F

-

-
-
-
-

---- -------- -
----------

----------

----------- ---
----
-

---- -
-- -
-

-- -
-

- --
----------
- -
----------
----------
---------- ----
----
-
----
----
---- ----
----
-
--
----
----
8/5/2004 0:00 8/6/2004 0:00 8/7/2004 0:00 8/8/2004 0:00
FA Temp FA DO - - Target DO
Figure 3.3-7. Falls 2004 Operations Test - Dissolved Oxygen and Temperature
Falls Releases
10000
9000
8000
7000
T
V 6000
d
A
5000
N_
a 4000
O
H
3000
2000
1000
0
8/5/040,00 8/6/040,00 8/7/040,00
GFA Tot Plant Discharge
Figure 3.3-8 Falls 2004 Operations Test - Discharge
8/8/040,00
10
- 9
- 8
- 7
6 E
O
5 ?
d
io
3
- 3
- 2
- 1
0
8/9/2004 0:00
8/9/040,00
Yadkin Project Water Quality Monitoring Study 98 Normandeau Associates
Water Quality
Falls DO Profile at Intake
370.00
360.00
350.00
c 340.00
Q
330.00
.c d
w 320.00
310.00
300.00
290.00 , I I F F
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00
DO, ppm
8/5/2004 @ 5 PM -Intake Top - -CL -Intake Bottom
Figure 3.3-9. Falls 2004 Operations Test - Intake Dissolved Oxygen Profile
High Rock Tailwater DO
87
85
83
m 81
m
m
rn
79
ai
3
y 77
a
E
m
~ 75
`m
m
3
'm 73
71
69
67
8/4/2004 000 8/5/2004 000 8/6/2004 000 8/7/2004 000
HR Temp HR DO - - Target DO
Figure 3.3-10. Rock 2004 Operations Test -Dissolved Oxygen and Temperature
8.00 9.00
10
9
8
7
6 6
E
O
5
`m
m
3
4 F
3
2
1
-10
8/8/2004 000
Yadkin Project Water Quality Monitoring Study 99 Normandeau Associates
Water Quality
High Rock Releases
10000
9000
8000
7000
N
6000
d
a
5000
N_
c
t0 4000
0
3000
2000
1000
0
8/4/04 0:00 8/5/04 0:00 8/6/04 0:00
OHR Tot Plant Discharge
Figure 3.3-11. High Rock 2004 Operations Test - Discharge
High Rock DO Profile at Intake
660.00
650.00
640.00
D
} 630.00
c
0
620.00
w
610.00
600.00
8/7/04 0:00 8/8/04 0:00
590.00
0.00 2.00 4.00 6.00 8.00 10.00 12.00
DO, ppm
8/5/2004 @ 1 PM -Intake Top - -CL -Intake Bottom
Figure 3.3-12. High Rock 2004 Operations Test - Intake Dissolved Oxygen Profile August 5,
2004
Yadkin Project Water Quality Monitoring Study 100 Normandeau Associates
Water Quality
High Rock DO Profile at Intake
660.00
650.00
640.00
D
} 630.00
c
0
620.00
w
610.00
600.00
590.00
0.00
2.00 4.00 6.00 8.00 10.00 12.00
DO, ppm
8/7/2004 @ 7 AM -Intake Top - -CL -Intake Bottom
Figure 3.3-13. High Rock 2004 Operations Test - Intake Dissolved Oxygen Profile August 7,
2004.
Tuckertown
The actual dissolved oxygen readings taken at 15-minute intervals in the Tuckertown tailwater are
presented in Figure 3.3-14, the Tuckertown discharge data are presented in Figure 3.3-15 and a
profile of the intake dissolved oxygen is presented in Figure 3.3-16. The Tuckertown data show that
• The reservoir dissolved oxygen at the start of the test, as shown in Figure 20, averages about
2 mg/1.
• Since air injection at High Rock did not result in a measurable increase in the High Rock
tailwater dissolved oxygen, no response was seen at the Tuckertown tailwater. The changes
in tailwater dissolved oxygen appear to be a result of operation of the Tuckertown units. The
diurnal cycles in the dissolved oxygen and temperature are not as evident at Tuckertown,
possibly because they are obscured by the peaking operations.
• The tailwater dissolved oxygen at Tuckertown increases over the test period, likely the result
of improved reservoir dissolved oxygen similar to High Rock.
3.3.3 Conclusions of Operation Testing
Though Yadkin was able to perform only the preliminary testing because of severe weather
conditions, in general, the 2004 testing was successful. Where possible, the 2001 data were compared
to the 2004 data and the comparison reveals that the trends from 2001 were generally repeated in the
2004 tests. The longer duration of each test in 2004 allowed the dissolved oxygen to come to
equilibrium following each configuration change and resulted in fewer erratic swings in dissolved
oxygen.
Yadkin Project Water Quality Monitoring Study 101 Normandeau Associates
Water Quality
Tuckertown Tailwater DO
87
85
83
LL
m 81
m
m
rn
79
ai
3
y 77
a
E
m
~ 75
`m
m
3
'm 73
71
69
67
8/4/2004 000 8/5/2004 000 8/6/2004 000 8/7/2004 000
TT Temp TT DO - - Target DO
Figure 3.3-14. Tuckertown 2004 Operations Test - Dissolved Oxygen and Temperature
Tuckertown Releases
10000
9000
8000
7000
N
d 6000
U
a
5000
N_
c
4000
O
F
3000
2000
1000
0
8/4/04 0:00 8/5/04 0:00 8/6/04 0:00
OTT Tot Plant Discharge
Figure 3.3-15. Tuckertown 2004 Operations Test - Discharge
10
9
8
7
6 6
E
O
5
`m
m
3
4 F
3
2
1
0
8/8/2004 000
8/7/04 0:00 8/8/04 0:00
Yadkin Project Water Quality Monitoring Study 102 Normandeau Associates
Water Quality
Tuckertown DO Profile at Intake
600.00
590.00
580.00
D
} 570.00
x
c
0
560.00
w
550.00
540.00
530.00
0.00
2.00 4.00 6.00 8.00 10.00 12.00
DO, ppm
8/5/2004 @ 11 AM -Intake Top - -CL -Intake Bottom
Figure 3.3-16. Tuckertown 2004 Operations Test - Intake Dissolved Oxygen Profile
Narrows
A comparison of the 2001 data to the 2004 data with respect to the effect of the Narrows Unit 4 air
valves reveals a response in the tailwater dissolved oxygen that is repeatable. Unit 4, operated alone
with two air injection valves open, increases the tailwater dissolved oxygen from 2 to 4 mg/l above
operation with no air valves. Operated in this manner, Unit 4 draws in water with a dissolved oxygen
of about I mg/l from the reservoir and introduces enough air in the water stream to maintain the
tailwater dissolved oxygen between 5 to 6 mg/1. The majority of the increase, about 88 percent, is
provided by opening the first air valve, and the balance is provided by opening the second valve.
Increasing the Narrows output by the sequential ramp up of Units 1, 2 and 3 to their best efficiency
point caused a 2 mg/1 drop in the tailwater dissolved oxygen, erasing the dissolved oxygen
improvement provided by the Unit 4 valves and dropping the dissolved oxygen to 3 to 4 mg/1. This
result leads to the conclusion that the air valves on Unit 4 alone cannot maintain the Narrows
tailwater at or above state standards with two or more units operating. And though the operation of
Units 1, 2 and 3 at 30 percent gate appeared to add air in the tailrace, the tailwater dissolved oxygen
measurements showed only a slight improvement. This result leads to the conclusion that operation
of Unit 4 and a combination of Units 1, 2 and 3 operating at either best efficiency or at 30 percent
gate will also not maintain the Narrows tailwater at or above state standards.
Falls
When Narrows and Falls are passing similar flows, dissolved oxygen improvements in the Narrows
tailwater are reflected in the Falls tailwater dissolved oxygen. When Narrows is operating at 5,000
cfs and higher, the controlled tests performed suggest that dissolved oxygen improvements in the
Narrows tailwater are reflected in the Falls tailwater dissolved oxygen within about two hours. As
Yadkin Project Water Quality Monitoring Study 103 Normandeau Associates
Water Quality
Narrows releases are reduced, dissolved oxygen improvements in the Narrows tailwater have less
effect on the Falls tailwater dissolved oxygen.
High Rock/Tuckertown
Injecting air through the bearing riser on the three High Rock units could not introduce enough air
into the discharge to improve the High Rock tailwater dissolved oxygen conditions. As a result, no
conclusions regarding whether improving High Rock tailwater dissolved oxygen would likewise
improve the dissolved oxygen below Tuckertown can be reached based on the 2004 tests.
In summary, the test data point to the following conclusions:
The air injection on Narrows Unit 4 clearly improves the tailwater dissolved oxygen. When
Unit 4 is operated alone with 2 air valves open, the unit takes in water from the reservoir at a
dissolved oxygen of about I mg/l and introduces enough air in the water stream that the
resulting tailwater dissolved oxygen is 5 to 6 mg/1. Given this result it follows that similar air
valves on all four Narrows units would likely maintain tailwater dissolved oxygen at or above
5 mg/l when the units are running.
• If state standards are met on a continuous basis in the Narrows tailwater it is likely that no
additional improvements will be required at Falls to assure that the Falls tailwater dissolved
oxygen meets state standards.
• Because the High Rock units did not improve the High Rock tailwater dissolved oxygen
conditions, no conclusions can be reached from the High Rock/Tuckertown test.
3.4 LATERAL AND LONGITUDINAL INVESTIGATION OF DISSOLVED OXYGEN IN
THE VICINITY OF THE DAMS
This investigation was undertaken in response to Issue Advisory Group (IAG) comments that
suggested that the influence of project operations may extend upstream and downstream beyond the
immediate vicinity of the dams during the period of summer stratification. The extremes of normal
project operations incorporating full generation and no generation were chosen to illustrate this effect,
if present.
The extent and degree of stratification behind each of the dams and downstream was evaluated during
one survey. This survey was conducted in August of 2004. A second survey was scheduled for
September of 2004 but had to be cancelled due to the presence of high river flows from the remnants
of two hurricanes. Two scenarios were evaluated during the survey. One scenario involved
monitoring after a prolonged (> 6 hour) period of generation at each facility. Monitoring under the
second scenario was after a prolonged (> 6 hour) period with no generation or spills at each facility.
During each reservoir survey, dissolved oxygen and temperature profiles were measured at the
quarter points in each of the four impoundments along transects spaced at 1/4 mile intervals starting at
the buoy line and proceeding upstream. Additional transects were added until two adjacent transects
showed similar profiles in terms of the depth of the thermocline and the extent of dissolved oxygen
depletion at depth. Reservoir transect locations are presented in Figures 3.4-1 through 3.4-4.
The dynamics of dissolved oxygen and temperature downstream of the dams were evaluated in a
similar fashion as the reservoir surveys. Starting at the continuous monitoring locations, dissolved
oxygen and temperature were measured by profile at the quarter points in the channel along transects
spaced at 1/4 mile increments downstream. Additional transects were added until observed
Yadkin Project Water Quality Monitoring Study 104 Normandeau Associates
Water Quality
dissolved oxygen and temperature at High Rock.
Yadkin Project Water Quality Monitoring Study 105 Normandeau Associates
Figure 3.4-1. Location of transects/sampling stations for lateral and longitudinal survey of
Water Quality
dissolved oxygen and temperature at Tuckertown.
Yadkin Project Water Quality Monitoring Study 106 Normandeau Associates
Figure 3.4-2. Location of transects/sampling stations for lateral and longitudinal survey of
Water Quality
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Figure 3.4-3. Location of transects/sampling stations for lateral and longitudinal survey of
dissolved oxygen and temperature at Narrows.
Yadkin Project Water Quality Monitoring Study 107 Normandeau Associates
Water Quality
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Figure 3.4-4. Location of transects/sampling stations for lateral and longitudinal survey of
dissolved oxygen and temperature at Falls.
Yadkin Project Water Quality Monitoring Study 108 Normandeau Associates
Water Quality
temperature and dissolved oxygen conditions at consecutive transects were similar or the river
channel became part of the next downstream impoundment. Tailrace transect locations are presented
in Figures 3.4-1 through 3.4-4.
The lateral and longitudinal survey was conducted on August 20 and 21, 2004. A schedule for the
full generation survey is presented in Table 3.4-1 while a schedule for the no generation survey is
presented in Table 3.4-2. The depth from the normal fill pond elevation to the intakes is presented in
Table 3.4-1. Schedule for lateral and longitudinal survey of dissolved oxygen and
temperature after 6 hours of full generation, August 20, 2004.
High Rock Tuckertown Narrows Falls
Beginning of generation 0700 0800 1100 1100
Beginning of reservoir survey 1200 1211 1446 1523
End of reservoir survey 1226 1312 1525 1550
Beginning of tailwater survey 1315 1404 1629 1649
End of tailwater survey 1334 1429 1700 1715
End of generation 1600 1600 1600a 1600a
'Generation at Narrows and Falls was gradually ramped down from full to zero from 1600 to 2200.
Table 3.4-2. Schedule for lateral and longitudinal survey of dissolved oxygen and
temperature after 6 hours with no generation, August 21, 2004.
High Rock Tuckertown Narrows Falls
Cessation of generation 2400 0100 2200 (8/20)a 2200 (8/20)a
Beginning of reservoir survey 1623 1425 1136 0926
End of reservoir survey 1641 1458 1159 0948
Beginning of tailwater survey 1536 1220 0959 0828
End of tailwater survey 1546 1230 1029 0844
Start of generation 8/23 8/23 8/23 8/23
'Narrows Unit 4 was run at 3 MW or roughly 10% of the full load for that unit throughout the no generation test. This
represents the standard no generation operating regime at Narrows due to a standing power contract. Units 1, 2 and 3 were
not operated during the test.
Table 3.4-3. The strata entrained in the turbine intakes is critical to the dissolved oxygen
concentration in the tailrace and may have an influence on the distribution of nearfield and farfield
dissolved oxygen in the impoundments. In general, there was only slight dissolved oxygen and
Table 3.4-3. Depth to intakes from normal full pond elevation.
Depth to Top
of Intakes Depth to Bottom
of Intakes
Project (m) (ft) (m) (ft)
High Rock 5.5 18.0 16.8 55.1
Tuckertown 9.9 32.5 18.1 59.4
Narrows 9.5 31.2 20.2 66.3
Falls 2.1 6.9 11.9 39.0
Yadkin Project Water Quality Monitoring Study 109 Normandeau Associates
Water Quality
temperature variability observed among any of the transects near any of the dams. Minimum,
maximum and mean dissolved oxygen by transect is presented in Table 3.4-3. The distribution of
dissolved oxygen within each transect was also very similar at each dam whether the units were
generatmg or not.
3.4.1 Results of Lateral and Longitudinal Survey
Summaries of the dissolved oxygen and temperature data are presented in Table 3.4-4 through 3.4-7.
Profile data and dissolved oxygen contour plots for each transect monitored during these surveys can
be found in Appendix K. Results are described in terms of comparisons between transects under each
generation survey, comparisons between profiles along each transect and comparisons of transects
between generation scenarios. The depth of the 5 mg/l dissolved oxygen contour is used as a
surrogate to evaluate changes in the size of the depleted oxygen zone between surveys and transects
(Table 3.4-8). Characteristics of the impoundments and facilities were presented in Table 1.0-1.
High Rock
Profiles taken along the transect F1 at the buoy line in the High Rock impoundment showed minimal
thermal stratification (surface - bottom differences of 2-4°C) but strong dissolved oxygen gradients
from top to bottom under both the generation and no generation scenarios (Table 3.4-4). Observed
surface dissolved oxygen concentrations were 10-11 mg/l while concentrations near the bottom were
2-3 mg/l. The primary difference between the profiles at this transect under different operational
conditions was the expansion of the depleted oxygen zone (Table 3.4-8). Under generation, the
waters with dissolved oxygen concentrations below 5 mg/1 were found below 7-11 meters (22-35 ft)
depth with the greatest effect seen at station IA (5 mg/1 at 6.4 meters) followed by IB then IC.
Station lA is on the same side of the river as the intakes for the turbines. Under the no-generation
scenario, the depleted oxygen zone (dissolved oxygen < 5 mg/1) was observed below 12 m at all three
stations along transect 1. At transect 2, the depleted dissolved oxygen zone was observed below 10 m
under both the generation and non-generation scenarios. The impact of generation on reservoir
dissolved oxygen in High Rock appears to be restricted to the immediate area of the dam. The turbine
intake depth at High Rock is 5.5 m to 16.8 m below the surface (18 to 55 ft below the surface). Water
pulled from this interval to the turbines appears to be replaced with water with lower oxygen content
deeper in the reservoir.
High Rock tailrace temperatures and dissolved oxygen concentrations were similar at all depths and
at both transects under each generating scenario. Temperatures observed at both tailrace transects
during the generation survey were 24.9°C. During the non-generation survey temperatures varied
from 25.6°C to 27.6°C. Dissolved oxygen concentrations in the tailrace varied from 4.3 and 5.3 mg/1
during generation and between 5.4 and 6.0 mg/l during the non-generation survey.
Tuckertown
The Tuckertown Impoundment is of similar depth to the High Rock impoundment. Similarly, it does
not thermally stratify to any great degree, however, depleted dissolved oxygen concentrations are
observed at depth. During the course of the surveys, there was minimal thermal stratification (surface
- bottom differences of 2°C). At the dam, Tuckertown impoundment is wider than the other three
Yadkin APGI impoundments at the dams, so 5 profiles were taken along each transect. Surface
dissolved oxygen concentrations were 12-13 mg/l (approximately 150% of saturation) during the
generation survey at both transect locations indicating that an intense algae bloom was occurring.
This was not observed to the same degree during the non-generation survey despite the fact that the
Yadkin Project Water Quality Monitoring Study 110 Normandeau Associates
Water Quality
Table 3.4-4. Summary of lateral and longitudinal dissolved oxygen and temperature results
(minimum, maximum and mean values in profiles) at High Rock project.
August 20-21, 2004.
Generatin 8/20/04 Non-Generatin 8/21/04
Temperature °C Dissolved Oxygen
Cone mg/L Temperature °C Dissolved Oxygen
Cone mg/L
Min Max Mean Min Max Mean Min Max Mean Min Max Mean
Transect Station
Forebay 1 A 23.7 26.8 25.2 2.1 11.2 6.3 23.8 28.5 26.1 1.8 11.1 8.2
B 23.9 27.0 25.4 3.3 9.8 6.8 24.0 28.2 26.1 2.5 11.0 8.0
C 24.0 26.7 25.5 3.4 9.6 7.2 24.1 28.2 26.2 2.9 11.3 8.4
2 A 23.9 26.9 25.7 3.2 11.3 8.6 24.1 27.7 26.2 2.8 9.9 7.8
B 23.8 26.9 25.5 3.0 11.4 8.0 24.0 27.5 26.1 2.7 10.0 7.9
C 24.1 27.1 25.9 3.7 11.6 8.6 24.0 28.1 26.3 2.8 10.6 8.5
Tailrace 1 A 24.9 24.9 24.9 4.4 4.6 4.5 26.0 27.5 27.0 5.5 5.6 5.5
B 24.9 24.9 24.9 4.5 4.6 4.5 25.7 27.6 26.8 5.8 6.0 5.9
C 24.9 24.9 24.9 4.6 4.7 4.7 26.6 27.2 26.9 6.0 6.0 6.0
2 A 24.9 24.9 24.9 5.0 5.3 5.2 25.6 27.7 26.5 5.4 5.6 5.5
B 24.9 24.9 24.9 4.3 4.5 4.4 26.3 27.5 26.9 5.6 5.7 5.6
C 24.9 24.9 24.9 4.7 4.8 4.7 26.7 27.1 26.9 5.4 5.4 5.4
Table 3.4-5. Summary of lateral and longitudinal dissolved oxygen and temperature results
(minimum, maximum and mean values in profiles) at the Tuckertown project,
August 20-21, 2004.
Generatin 8/20/04 Non-Generatin 8/21/04
Temperature °C Dissolved Oxygen
Cone m /L Temperature °C Dissolved Oxygen
Cone m L
Min Max Mean Min Max Mean Min Max Mean Min Max Mean
Transect Station
Forebay 1 A 25.0 27.8 26.4 3.2 12.4 9.0 25.1 27.9 26.1 3.4 9.5 6.0
B 25.0 28.0 26.4 3.6 12.2 8.6 25.0 27.8 26.2 3.6 9.7 6.7
C 25.0 27.4 26.0 3.8 13.0 7.9 24.9 27.1 26.0 3.1 9.8 6.7
D 25.1 27.1 25.9 3.7 12.1 7.2 25.0 27.5 26.0 3.4 9.1 5.9
E 25.2 29.1 26.7 4.1 12.7 9.6 25.2 27.4 26.2 3.3 8.9 6.3
2 A 25.0 28.5 26.6 3.1 13.3 9.5 25.1 27.6 26.4 3.8 8.6 6.7
B 25.0 28.4 26.5 3.3 12.6 8.5 25.0 27.4 26.2 3.5 8.5 6.6
C 25.0 28.2 26.5 3.7 12.7 8.9 24.9 27.1 26.0 3.2 8.4 5.9
D 25.1 28.4 26.4 4.3 12.7 8.4 25.0 27.2 26.1 3.7 7.7 6.0
E 25.1 28.0 26.4 3.9 11.9 8.0 25.0 27.3 26.0 3.2 7.4 5.4
Tailrace 1 A 25.7 25.7 25.7 4.3 4.5 4.4 26.3 27.6 27.2 8.7 8.9 8.8
B 25.7 25.7 25.7 4.5 4.6 4.6 26.9 27.6 27.3 9.0 9.1 9.0
C 25.7 25.7 25.7 4.5 4.6 4.6 27.6 27.7 27.6 8.9 8.9 8.9
2 A 25.7 25.7 25.7 4.4 4.5 4.5 26.0 28.2 27.3 8.7 9.6 9.4
B 25.8 25.8 25.8 4.5 4.5 4.5 26.5 28.1 27.5 8.8 9.4 9.3
C 25.7 25.8 25.7 4.2 4.3 4.2 26.2 28.3 27.6 9.2 9.6 9.4
Yadkin Project Water Quality Monitoring Study III Normandeau Associates
Water Quality
Table 3.4-6. Summary of lateral and longitudinal dissolved oxygen and temperature results
(minimum, maximum and mean values in profiles) at the Narrows project.
August 20-21, 2004.
Generatin 8/20/04 Non-Generatin 8/21/04

Temperature °C Dissolved Oxygen
Cone mg/L
Temperature °C Dissolved Oxygen
Cone mg/L
Min Max Mean Min Max Mean Min Max Mean Min Max Mean
Transect Station
Forebay 1 A 7.6 27.5 19.8 0.6 9.0 3.9 8.0 26.7 20.5 1.1 5.9 3.0
B 7.5 27.4 17.8 0.7 8.0 3.4 7.4 26.7 16.7 0.5 6.5 2.4
C 8.1 27.2 21.2 0.9 6.8 3.8 7.7 26.8 19.9 0.8 6.4 3.0
2 A 13.4 27.8 25.9 1.3 9.1 5.3 11.4 26.7 24.5 1.3 5.7 3.6
B 7.6 27.6 19.1 0.5 8.6 3.7 7.5 26.7 18.8 0.6 6.4 2.9
C 7.8 27.8 19.8 0.8 7.7 4.0 7.5 26.7 18.5 0.7 5.9 2.7
Tailrace 1 A 26.4 26.5 26.4 5.8 6.2 6.0 26.3 26.3 26.3 6.8 6.8 6.8
B 26.2 26.2 26.2 4.3 4.4 4.4 26.3 26.3 26.3 6.9 6.9 6.9
C 26.1 26.1 26.1 4.1 4.2 4.2 26.3 26.3 26.3 6.9 6.9 6.9
2 A 26.3 26.3 26.3 5.3 5.4 5.3 26.3 26.3 26.3 6.7 6.7 6.7
B 26.2 26.2 26.2 5.1 5.1 5.1 26.3 26.3 26.3 6.8 6.8 6.8
C 26.1 26.1 26.1 4.9 4.9 4.9 26.3 26.3 26.3 6.8 6.8 6.8
3 A 26.4 26.4 26.4 4.4 4.6 4.5 26.2 26.3 26.2 6.6 7.1 6.8
B 26.3 26.3 26.3 5.1 5.1 5.1 26.3 26.3 26.3 6.6 6.7 6.6
C 26.1 26.2 26.2 4.8 5.1 5.0 26.3 26.3 26.3 6.6 6.7 6.7
4 A 26.4 26.4 26.4 4.7 4.7 4.7 26.2 26.2 26.2 6.4 6.6 6.5
B 26.4 26.5 26.5 4.7 4.8 4.8 26.2 26.2 26.2 6.5 6.7 6.6
C 26.2 26.2 26.2 4.6 4.7 4.6 26.2 26.3 26.2 6.5 6.6 6.6
Table 3.4-7. Summary of lateral and longitudinal dissolved oxygen and temperature results
(minimum, maximum and mean values in profiles) at the Falls project. August
20-21, 2004.
Generating 8/20/04 Non-Generating 8/21/04

Temperature °C Dissolved Oxygen
Cone mg/L
Tem erature °C Dissolved Oxygen
Cone mg/L
Min Max Mean Min Max Mean Min Max Mean Min Max Mean
Transect Station
Forebay 1 A 26.3 27.1 26.7 5.5 6.4 6.1 26.3 26.4 26.3 4.1 5.0 4.7
B 26.3 27.0 26.6 5.3 6.0 5.6 26.3 26.4 26.3 3.9 4.8 4.4
C 26.2 27.4 26.6 5.2 5.8 5.5 26.2 26.4 26.3 3.6 5.3 4.4
2 A 26.3 27.6 26.8 4.7 6.0 5.5 26.3 26.4 26.3 4.0 4.9 4.6
B 26.3 27.1 26.6 4.6 5.5 5.0 26.2 26.4 26.3 3.0 4.9 4.4
C 26.4 26.8 26.5 4.7 5.3 5.1 26.2 26.4 26.3 3.7 4.8 4.2
Tailrace 1 A 26.6 26.6 26.6 6.0 6.0 6.0 26.0 26.1 26.1 5.0 5.0 5.0
B 26.6 26.6 26.6 5.9 5.9 5.9 26.1 26.1 26.1 4.8 4.8 4.8
C 26.6 26.7 26.6 5.8 5.8 5.8 26.1 26.2 26.2 5.0 5.1 5.1
2 A 26.7 26.8 26.7 6.0 6.0 6.0 25.9 26.0 25.9 5.3 5.3 5.3
B 26.6 26.6 26.6 5.9 5.9 5.9 26.1 26.1 26.1 5.4 5.4 5.4
C 26.7 26.7 26.7 5.8 5.8 5.8 26.1 26.1 26.1 5.2 5.2 5.2
Yadkin Project Water Quality Monitoring Study 112 Normandeau Associates
Water Quality
Table 3.4-8. Depth to 5 mg/l dissolved oxygen contour in Yadkin Project Impoundments
during lateral and longitudinal surveys. August 20-21, 2004.
First Forebay Depth Observation where Dissolved Oxygen <5 mg/l

Generating August 20,2004 Non-Generating August 21,
2004

Depth Temperature
(°C
Depth Temperature
(°C
Dam File (m) (ft) (m) (ft)
High Rock HF1A 6.4 (21.0) 25.3 12.6 (41.3) 24.3
HF1B 9.8 (32.2) 25.0 12.0 (39.4) 24.8
HF1C 10.8 (35.4) 24.9 11.6 (38.1) 24.9
HF2A 11.4 (37.4) 24.6 10.8 (35.4) 25.0
HF2B 12.3 (40.4) 24.4 11.5 (37.7) 24.7
HF2C 10.9 (35.8) 24.7 12.1 (39.7) 24.3
Tuckertown TF1A 14.1 (46.3) 25.3 7.1 (23.3) 25.7
TF1B 13.6 (44.6) 25.3 11.0 (36.1) 25.5
TF1C 11.4 (37.4) 25.5 10.7 (35.1) 25.5
TF1D 9.6 (31.5) 25.5 8.4 (27.6) 25.7
ME 11.5 (37.7) 25.4 7.1 (23.3) 25.9
TF2A 11.6 (38.1) 25.5 10.5 (34.4) 25.5
TF2B 11.7 (38.4) 25.5 11.0 (36.1) 25.5
TF2C 12.5 (41.0) 25.4 9.0 (29.5) 25.6
TF2D 11.3 (37.1) 25.5 9.2 (30.2) 25.7
TF2E 9.4 (30.8) 25.6 7.5 (24.6) 25.8
Narrows NF1A 10.1 (33.1) 26.5 5.8 (19.0) 26.5
NF1B 13.8 (45.3) 26.5 7.5 (24.6) 26.5
NF1C 11.0 (36.1) 26.6 7.2 (23.6) 26.5
NF2A 10.9 (35.8) 26.5 8.9 (29.2) 26.5
NF2B 12.6 (41.3) 26.5 9.4 (30.8) 26.5
NF2C 14.5 (47.6) 26.5 6.5 (21.3) 26.5
Falls FF1A see Note see Note 0.1 (0.3) 26.4
FF1B see Note see Note 0.1 (0.3) 26.4
FF1C see Note see Note 1.6 (5.2) 26.4
FF2A 11.6 (38.1) 26.4 0.2 (0.7) 26.4
FF2B 10.4 (34.1) 26.4 0.2 (0.7) 26.4
FF2C 12.1 (39.7) 26.4 0.4 (1.3) 26.4
Note: Dissolved oxygen >_5/mg/l at all depths.
surveys were conducted at a similar time of day and within one day of each other (Tables 3.4-1 and
3.4-2). During the non-generation survey, dissolved oxygen concentrations near the surface were 8-
10 mg/l. During both surveys, dissolved oxygen concentrations near the bottom were 3.0-4.0 mg/l
(Appendix K).
At transect 1 the waters with dissolved oxygen concentrations < 5 mg/l were below 9.5-14.0 m (31-
46 feet) during generation and below 7.0-11.0 m during non-generation (Table 3.4-8). The
differences in the profiles between surveys were more pronounced at the ends of transect 1 than at the
mid-channel stations. Mid-channel profiles were similar for both surveys. During generation,
dissolved oxygen concentrations less than 5 mg/l were found at depths below 9.5-12.5 m (31-41 feet)
Yadkin Project Water Quality Monitoring Study 113 Normandeau Associates
Water Quality
along transect 2. During non-generation transect 2 waters with dissolved oxygen concentrations
below 5 mg/1 were found below 7-11 m, similar to observations at transect 1..
At Tuckertown, generation appears to increase the volume of oxygenated water in the vicinity of the
intakes. The 5 mg/l contour is at a greater depth during generation. The turbine intake depth at
Tuckertown is slightly deeper than that at High Rock ranging from 9.9 meters below the surface to
18.1 meters (32-59 feet) or essentially just above the maximum depth of the reservoir. Generation
appears to draw oxygenated surface water downward towards the intakes in the Tuckertown
impoundment. This effect is most pronounced in the immediate vicinity of the intakes but is also
observed to a lesser degree 1/4 mile upstream at transect 2.
Tuckertown tailrace dissolved oxygen concentrations were markedly different between the generation
and non-generation surveys (Table 3.4-5). During the generation survey, dissolved oxygen
concentrations ranged from 4.2-4.6 mg/1 while during the non-generation survey, concentrations were
between 8.7 and 9.6 mg/1. Algal cells from the Tuckertown headpond were likely carried into the
tailrace during the generation survey and produced substantial amounts of oxygen during the non-
generation survey. Continuous monitoring data from the Tuckertown tailrace (Section 2.4, Appendix
I) shows tailrace dissolved oxygen concentrations of 3.65 at 0100 on August 21 when generation
ceased. Dissolved oxygen remained at or slightly below that concentration until daylight. The
concentration steadily increased to around 10 mg/l at the time of the survey (1400) suggesting
substantial algal oxygen production.
Narrows
The Narrows impoundment is the only impoundment in the Yadkin Project system that is frequently
thermally stratified. During the course of the two surveys, differences between surface and bottom
temperatures were on the order of 10-20°C which indicates relatively strong thermal stratification
(Table 3.4-6, Appendix K).
During both surveys, dissolved oxygen near the bottom of both transects was below I mg/1. At the
surface, concentrations varied from 6.5-9.0 mg/1 at transect I during generation (Appendix K). At
transect 2 this variability in dissolved oxygen concentration at the surface was not as great
(concentrations from 6.0-8.2 mg/1) during generation. During the generation surveys, the maximum
observed dissolved oxygen concentration was not at the surface in all instances (Appendix K) but was
observed within the upper 10 meters (33 feet). During non-generation, surface concentrations were
similar at both transects (5.7-6.5 mg/1, Appendix K). At transect 1, dissolved oxygen concentrations
below 5 mg/l were found from 10-13 m during generation with the greatest volume of water with
depleted dissolved oxygen being observed at station C which is furthest from the intakes (Table 3.4-
8). During non-generation at transect 1, water with dissolved oxygen concentrations below 5 mg/l
was observed below 5.5 m at all stations along the transect (Table 3.4-8). At transect 2
concentrations below 5 mg/1 were observed below 10.5-14.0 m during generation and 6.5-9.0 m
during non-generation. The influence of generation appears to be to draw oxygenated water deeper
into the impoundment. This phenomenon is further illustrated in Figure 3.4-5. The intake depth is
above the thermocline so water entrained in the turbines is freely mixed to the surface. When
generation is not occurring, the water at the bottom of the epilimnion lacks oxygen. This is likely
attributable to the microbial decomposition of algal cells below the photic zone.
In the Narrows tailrace, concentration of dissolved oxygen under generation ranged from 4.1-6.2
(Table 3.4-6, Appendix K). The majority of the readings ranged from 4.5-5.2 mg/1. The two notable
Yadkin Project Water Quality Monitoring Study 114 Normandeau Associates
Water Quality
Generating August 20, 2004
0
10
20
w
30
a
40
50
0
10
20
N
? a
d 30
40
Intakes 9.5. 20 meters
l
Temperature
- - DO
0 5 10 15 20 25 30
Temperature (°C)
I i
0 1 2 3 4 5 6 7 S 9 10
DO (mgll)
Non-Generating August 21, 2004
Intakes 9.5 - 20 meters
r
r
r
J
r
50
Temperature
--- DO
0 5 10 15 20 25 30
Temperature (°C)
0 1 2 3 4 5 6 7 8 9 10
DO (mgll)
Figure 3.4-5. Temperature and dissolved oxygen at Transect 1 Station B, Narrows
impoundment (y axis scale of 0-50 meters is equivalent to 0-164 feet).
Yadkin Project Water Quality Monitoring Study 115 Normandeau Associates
Water Quality
exceptions were the readings at station IA closest to unit 4 (with air injection) where the highest
readings were observed and at the surface at station 1C where a concentration of 4.1 was observed.
This concentration was isolated to this station and may have been related to water from units 1, 2 and
3 with no air injection. Readings from the center station of transect 1 (1B) where the continuous
monitor is located were consistent with readings observed at downstream transects. Under the no-
generation scenario, all four transects exhibited concentrations of 6.5-7.1 mg/1 (Appendix K).
Falls
Thermal stratification was not observed in the Falls impoundment. Differences between the surface
and bottom were less than 1°C. The distribution of dissolved oxygen in the impoundment was similar
between transects during both generating and non-generating scenarios (Appendix K). During the
non-generating scenarios, dissolved oxygen concentrations ranged from 3.0 to 5.3. During the
generating scenarios, dissolved oxygen concentrations ranged from 4.6 to 6.4 (Table 3.4-7). Because
the Falls impoundment is so small, it is likely that the observed impoundment dissolved oxygen
concentrations are more closely related to generation at Narrows than generation at Falls. The
reservoir is well mixed. The slightly lower concentrations observed during the non-generating survey
could be related to the timing of the surveys and diurnal fluctuation of dissolved oxygen
concentrations related to algal effects. The generating survey was conducted in the afternoon (15:23-
15:50) when net algal oxygen production would be near peak while the non-generating survey was
conducted fairly early the following morning (09:26-09:48) when net algal oxygen production would
be lower. At the transect closest to the dam dissolved oxygen was greater than 5 mg/l at all depths
during the generation survey (Table 3.4-8). At transect 2, the depth where dissolved oxygen was less
than 5 mg/l was 10.4-12.1 m. During non-generation nearly the entire water column had dissolved
oxygen concentrations <5 mg/l at both transects.
Tailrace dissolved oxygen concentrations below Falls ranged from 5.8-6.0 at both transects during
generation and from 4.8-5.4 at both transects during non-generation (Table 3.4-7). These
observations are consistent with readings from the Falls impoundment and are likely (especially for
the generation scenario) highly influenced by operations at Narrows.
3.5 SUSPENDED SOLIDS TRANSPORT THROUGH THE YADKIN APGI SYSTEM
Total Suspended Solids
Total suspended solids (TSS) were monitored monthly from June 1999 to December 2003 at 20
stations located on the Yadkin River and in the Yadkin Project reservoirs. To evaluate the transport
of TSS through the Yadkin Project, the data for the monitoring stations located along the mainstem of
the Yadkin River were analyzed including:
High Rock Reservoir: H1, H3, H7 and H10
Tuckertown Reservoir: T1, T2 and T3
Narrows Reservoir: N1, N2 and N4
Falls Reservoir: F1, F2 and F3
concentrations for these stations were then plotted versus distance downstream from monitoring
station H1 (Figure 3.5-1). Average TSS concentration decreases from 46.9 mg/L where the Yadkin
River enters High Rock Reservoir (Station H1) to 2.8 mg/L in the Yadkin River downstream of the
Falls Dam (Station F3). This represents a decrease in TSS concentration of 94 percent. The greatest
change, by concentration, consistently occurred in High Rock Reservoir where the average TSS
Yadkin Project Water Quality Monitoring Study 116 Normandeau Associates
D
0
0
M
M
A
p
c
D
0
O
z
0
A
z
c?
U)

Z
0
Q
m
c
n
0
ca'
<D
(n
60
50
J
0)
E 40
C
0
N
30
U
c
0
cU) 20
U)
F--
10
0
0
High Rock Tuckertown Narrows Falls Yadkin R.

Average TSS
Concentration - -' -

% Difference
From H1
5 10 15 20 25 30
River Mile Downstream of H1 to F3
Figure 3.5-1. Average TSS Concentration vs. Distance Downstream of H1, June 1999 through 2003.
- 100
90
80 _
70 E
O
60 a)
U
C
50 m
40
c
30 2
a)
0-
20
10
0
35 40

lD
A
I
Water Quality
concentration decreased by 31.6 mg/L between the upper most monitoring station (HI) and the lower
most monitoring station (1110). On average, TSS concentrations decreased by 4.0 mg/L in Narrows
Reservoir and 0.2 mg/L in Falls Reservoir. Tuckertown was the only reservoir to have an increase in
average TSS concentrations, although relatively small (0.7 mg/L). The increase usually occurred
between monitoring stations TI and T2. Lick Creek, Cabin Creek, Flat Creek and at least two
unnamed tributaries are possible sources of sediment input in this reach of Tuckertown Reservoir.
The range in TSS concentrations through the Yadkin Project is shown in Figure 3.5-2. The greatest
range in TSS concentrations has been experienced in High Rock Reservoir, while downstream, the
range in TSS concentrations form a much narrower band around the mean. Also, the range in TSS
concentrations decreases through High Rock Reservoir. This suggests that the greatest variability is
associated with the sediment transport associated with the Yadkin River, which decreases as flow
passes through High Rock Reservoir. This variability is most likely due to the relationship between
discharge and TSS concentration. As shown in Figure 3.5-3, the highest average TSS concentrations
in High Rock Reservoir (Station HI) typically occur in response to high discharge events that occur
either in the late winter/early spring or in the summer/late fall. These high discharge events are
associated with regional storm systems that produce significant runoff which entrains sediment from
the drainage basin and transports it to the Yadkin River and its tributaries.
The percent change in the average TSS concentrations within each impoundment and their cumulative
values through the Yadkin Project were calculated (Table 3.5-1) and the results are presented in
Figure 3.5-4. By impoundment, the average TSS concentration decreased in High Rock Reservoir,
Narrows Reservoir and in the Falls Reservoir, while they increased slightly in Tuckertown Reservoir.
High Rock Reservoir had the greatest percentage decrease in TSS concentration, averaging 58 percent
over the period of record, followed by Narrows (47.4 percent) and Falls (2.6 percent). As mentioned
previously, average TSS concentrations increased in the Tuckertown Reservoir (6.5 percent). Again,
these data indicate that High Rock Reservoir is the principal sink for TSS in the Yadkin Project
system, with additional TSS retention in Narrows and Falls. Although there is an increase in TSS in
the Tuckertown Reservoir, this gain is most likely reduced by losses in the Narrows and Falls
Reservoirs.
3.6 BIOLOGICAL ISSUES
There are numerous biological issues related to the operation of the Yadkin APGI Facilities.
Fisheries, wetlands and wildlife issues are covered companion reports to this report (Normandeau
2004, Normandeau 2005a, Normandeau 2005b). Two issues not covered in companion reports,
mercury in fish tissue and bacterial contamination are discussed below.
3.6.1 Mercury in Fish Tissue
From September I to 3, 2003, ten specimens each of largemouth bass, black crappie and channel
catfish were collected from the vicinity of the Tuckertown Dam tailrace (upper Narrows Reservoir)
for the purpose of testing mercury accumulation in fish tissue. The mercury concentration in fish
fillets was analyzed. Specimens were collected by Normandeau Associates personnel by a
combination of gill nets and electrofishing. Samples were sent to Microbac Laboratories, Inc. for
analysis using standard methods EPA 245.1.
The mercury concentrations were below the detection in all the fish that were collected (Table 3.5-1 ).
The detection limit (0.145 mg/kg) was below the US FDA action level of I mg/kg.
Yadkin Project Water Quality Monitoring Study 118 Normandeau Associates
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River Mile Downstream of H1 to F3
Figure 3.5-2. Range in TSS Values vs. Distance Downstream of Hl, June 1999 through 2003.

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Table 3.5-1. Summary of Average Annual TSS Concentration (mg/L) for Monitoring Stations along the Mainstem of the Yadkin
River from June 1999 through 2003.
1999 2000 2001 2002 2003
TSS % TSS % TSS % TSS % TSS % Average
Reservoir and Station Conc. Cum. 4 Conc. Cum. 4 Conc. Cum. 4 Conc. Cum. 4 Conc. Cum. 4 Annual
High Rock
H1 26.8 75.3 28.8 25.7 77.7 46.9
H3 30.4 -0.1 42.7 0.4 47.0 -0.7 25.2 0.0 31.1 0.6 35.3
H7 21.0 0.4 26.4 0.2 20.5 1.0 18.2 0.3 16.6 0.2 20.5
H10 15.7 0.2 18.3 0.1 14.1 0.2 16.2 0.1 11.8 0.1 15.2
Cone. Change in Impound. 11.1 56.9 14.7 9.5 65.9 31.6
%Im oundment Change 0.4 0.4 0.8 0.8 0.5 0.6 0.4 0.4 0.8 0.9 0.6
Tuckertown
Tl 10.8 0.2 11.6 0.1 10.3 0.1 9.4 0.3 8.9 0.0 10.2
T2 13.2 -0.1 11.8 0.0 12.4 -0.1 10.7 -0.1 10.9 0.0 11.8
T3 12.2 0.0 12.2 0.0 11.2 0.0 10.7 0.0 8.2 0.0 10.9
Cone. Change in Impound. -1.5 -0.6 -0.9 -1.3 0.7 -0.7
%Impoundment Change -0.1 0.1 -0.1 0.1 -0.1 0.1 -0.1 0.2 0.1 0.0 -0.1
Narrows
N1 10.6 0.1 8.6 0.0 6.8 0.2 6.5 0.2 7.4 0.0 8.0
N2 5.8 0.2 5.9 0.0 5.7 0.0 4.9 0.1 7.3 0.0 5.9
N4 2.8 0.1 3.0 0.0 3.3 0.1 3.0 0.1 8.0 0.0 4.0
Cone. Change in Impound. 7.8 5.7 3.6 3.5 -0.6 4.0
%Impoundment Change 0.7 0.4 0.7 0.1 0.5 0.3 0.5 0.3 -0.1 0.0 0.5
Falls
171 1.8 0.0 4.0 0.0 2.5 0.0 2.9 0.0 3.6 0.1 2.9
F2 3.0 0.0 3.1 0.0 3.1 0.0 2.6 0.0 3.5 0.0 3.1
F3 2.0 0.0 2.7 0.0 2.7 0.0 2.7 0.0 3.8 0.0 2.8
Cone. Change in Impound. -0.2 1.3 -0.2 0.2 -0.2 0.2
%Im oundment Change -0.1 0.0 0.3 0.0 -0.1 0.0 0.1 0.0 -0.1 0.1 0.0
Total Cone. Change H1-
F3 24.8 72.5 26.1 23.0 74.0 44.1
% Total Change in TS S 0.9 1.0 1.0 1.0 0.9 1.0 0.9 1.0 1.0 1.0 0.9

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High Rock Tuckertown Narrows Falls
Water Quality
In general, state water quality standards to protect aquatic life for non-carcinogenic substances are
more stringent than numerical standards to protect human health from consumption of fish. Mercury
is probably not accumulating in fish tissue to levels that pose a threat to human health.
3.6.2 Fecal Coliform Monitoring
Monitoring for fecal coliform in waters associated with the High Rock, Tuckertown, Narrows and
Falls developments of the Pee Dee River is handled by both the State's Division of Water Quality
and, as needed, by the Health Department at the County level.
Through the NCDENR Division of Water Quality, the State monitors fecal coliform on a five-year
cycle, with 2005 being the next sampling year. Grab samples are collected at the surface of the lake
in the mainstem of the lakes; most likely rendering them not representative of conditions associated
with swimming or developed areas. Table 3.6-2 shows collected data for the High Rock Lake,
Tuckertown Reservoir and Badin Lake for the years 1999 to 2001; the Falls Reservoir was last
sampled in 1994. All of the samples were below the State standard for Class C waters of 200 per 100
MI.
Concerns or complaints expressed by the local population generally get directed to the Health
Department within the respective County. Stanly, Davidson and Rowan Counties had no logged
complaints requiring any fecal coliform monitoring.
Yadkin Project Water Quality Monitoring Study 123 Normandeau Associates
Water Quality
Table 3.6-1. The concentration of mercury in fish tissue of largemouth bass, black crappie
and channel catfish collected in Tuckertown tailrace (upper Narrows reservoir)
September 1-3, 2003.
Length Mercury
mm mg/kg
Species
Largemouth Bass 438 <0.144
Largemouth Bass 444 <0.145
Largemouth Bass 458 <0.147
Largemouth Bass 432 <0.144
Largemouth Bass 413 <0.145
Largemouth Bass 443 <0.147
Largemouth Bass 357 <0.146
Largemouth Bass 371 <0.145
Largemouth Bass 355 <0.147
Largemouth Bass 377 <0.145
Black Crappie 297 <0.146
Black Crappie 255 <0.146
Black Crappie 255 <0.148
Black Crappie 292 <0.144
Black Crappie 291 <0.147
Black Crappie 244 <0.143
Black Crappie 223 <0.149
Black Crappie 235 <0.148
Black Crappie 246 <0.147
Black Crappie 225 <0.149
Channel Catfish 373 <0.144
Channel Catfish 449 <0.142
Channel Catfish 355 <0.148
Channel Catfish 440 <0.145
Channel Catfish 414 <0.148
Channel Catfish 473 <0.146
Channel Catfish 466 <0.147
Channel Catfish 389 <0.146
Channel Catfish 466 <0.144
Channel Catfish 405 <0.150
Yadkin Project Water Quality Monitoring Study 124 Normandeau Associates
Water Quality
Table 3.6-2 Fecal coliform data collected by NCDENR in the Yadkin reservoirs.

Lake Name
Date
m/d/yr
Sampling
Station Fecal
Coliform
per 100 ml
High Rock Lake August 16, 2001 YAD152A 6
High Rock Lake August 16, 2001 YAD152C 1
High Rock Lake August 16, 2001 YAD156A 1
High Rock Lake August 16, 2001 YAD169A 1
High Rock Lake August 16, 2001 YAD169B 1
High Rock Lake August 16, 2001 YAD169E 1
High Rock Lake August 16, 2001 YAD169F 1
High Rock Lake July 31, 2001 YAD169E 2
High Rock Lake August 1, 2000 YAD152A <10
High Rock Lake August 1, 2000 YAD152C <10
High Rock Lake August 1, 2000 YAD156A <10
High Rock Lake August 1, 2000 YAD169A <10
High Rock Lake August 1, 2000 YAD169B <10
High Rock Lake August 1, 2000 YAD169E <10
High Rock Lake August 1, 2000 YAD169F <10
High Rock Lake July 5, 2000 YAD1391A 73
High Rock Lake July 5, 2000 YAD152A <10
High Rock Lake July 5, 2000 YAD152C <10
High Rock Lake July 5, 2000 YAD156A <10
High Rock Lake July 5, 2000 YAD169A 27
High Rock Lake Jul 5, 2000 YAD169B <10
High Rock Lake Jul 5, 2000 YAD169E <10
High Rock Lake July 5, 2000 YAD169F <10
High Rock Lake June 20, 2000 YAD1391A 64
High Rock Lake June 20, 2000 YAD152A <10
High Rock Lake June 20, 2000 YAD152C <10
High Rock Lake June 20, 2000 YAD156A <10
High Rock Lake June 20, 2000 YAD169A <10
High Rock Lake June 20, 2000 YAD169B <10
High Rock Lake June 20, 2000 YAD169E <10
High Rock Lake June 20, 2000 YAD169F <10
High Rock Lake August 26, 1999 YAD152A 10
High Rock Lake August 26, 1999 YAD152C 30
High Rock Lake August 26, 1999 YAD156A <10
High Rock Lake August 26, 1999 YAD169A <10
High Rock Lake August 26, 1999 YAD169B <10
High Rock Lake August 26, 1999 YAD169E <10
High Rock Lake August 26, 1999 YAD169F 10
(continued)
Yadkin Project Water Quality Monitoring Study 125 Normandeau Associates
Water Quality
Table 3.6-2 (Continued)

Lake Name
Date
m/d/ r
Sampling
Station Fecal
Coliform
per 100 ml
High Rock Lake July 15, 1999 YAD1391A 70
High Rock Lake July 15, 1999 YAD152A <10
High Rock Lake July 15, 1999 YAD152C <10
High Rock Lake July 15, 1999 YAD156A <10
High Rock Lake July 15, 1999 YAD169A 10
High Rock Lake July 15, 1999 YAD169B <10
High Rock Lake Jul 15, 1999 YAD169E <10
High Rock Lake Jul 15, 1999 YAD169F 10
High Rock Lake June 3, 1999 YAD1391A <10
High Rock Lake June 3, 1999 YAD152A <10
High Rock Lake June 3, 1999 YAD152C <10
High Rock Lake June 3, 1999 YAD156A <10
High Rock Lake June 3, 1999 YAD169A 30
High Rock Lake June 3, 1999 YAD169B <10
High Rock Lake June 3, 1999 YAD169E <10
High Rock Lake June 3, 1999 YAD169F <10

Tuckertown Reservoir August 3, 1999 YAD172C 10
Tuckertown Reservoir August 3, 1999 YAD1780A <10
Tuckertown Reservoir July 8, 1999 YAD172C <10
Tuckertown Reservoir July 8, 1999 YAD1780A <10
Tuckertown Reservoir June 3, 1999 YAD172C <10
Tuckertown Reservoir June 3, 1999 YAD1780A <10

Badin Lake August 3, 1999 YAD178B <10
Badin Lake August 3, 1999 YAD178E <10
Badin Lake August 3, 1999 YAD178F <10
Badin Lake August 3, 1999 YAD178F1 <10
Badin Lake Jul 8, 1999 YAD178B <10
Badin Lake July 8, 1999 YAD178E <10
Badin Lake July 8, 1999 YAD178F <10
Badin Lake July 8, 1999 YAD178F1 <10
Badin Lake June 7, 1999 YAD178B <10
Badin Lake June 7, 1999 YAD178F1 <10
Yadkin Project Water Quality Monitoring Study 126 Normandeau Associates
Water Quality
4.0 REFERENCES
Alcoa Power Generating, Inc. (APGI) Yadkin Division. 2002, Yadkin Hydroelectric Project FERC
No. 2197-NC. Initial Consultation Document.
Clark, K.R. and R.M. Warwick. 1997. Change in Marine Communities; An Approach to Statistical
Analysis and Interpretation. Plymouth Marine Laboratory, Bourne Press Limited,
Bournemouth, UK.
Helsel, D.R. and R.M. Hirsch. 1991. Statistical methods in Water Resources. Chapter A3. United
States Geologic Survey, Reston, VA.
NALMS. 1990. Lake and Reservoir Restoration Guidance Manual. EPA-440/4-90-006.
Normandeau Associates, Inc. 2001. Yadkin Project Dissolved Oxygen Monitoring Plan. Prepared
for Alcoa Power Generating, Inc., Yadkin Division.
Normandeau Associates, Inc. 2002. Baseline Water Quality at the Yadkin Project. Prepared for
Alcoa Power Generating, Inc., Yadkin Division.
Normandeau Associates, Inc. 2003. Yadkin Project (FERC No. 2197) 2003 Water Quality
Monitoring Study Plan. Prepared for Alcoa Power Generating, Inc., Yadkin Division.
Normandeau Associates, Inc. 2004. Yadkin Project (FERC No. 2197) 2004 Tailrace Dissolved
Oxygen Study Plan. Prepared for Alcoa Power Generating, Inc., Yadkin Division.
Normandeau Associates, Inc. 2004. Draft Rare, Threatened and Endangered Species Report.
Prepared for Alcoa Power Generating, Inc., Yadkin Division.
Normandeau Associates, Inc. 2005a. Draft Wetland and Riparian Habitat Assessment. Prepared for
Alcoa Power Generating, Inc., Yadkin Division.
Normandeau Associates, Inc. 2005b. Draft Tailwater Fisheries Report. Prepared for Alcoa Power
Generating, Inc., Yadkin Division.
North Carolina Department of Environmental Management (NCDEM). 1989. North Carolina Lakes
Monitoring Report No. 89-04.
North Carolina Department of Environmental Management (NCDEM). 2004. ISA. NCAC 2b
.0100-.0300.
North Carolina Department of Environmental Management (NCDEM). 2004. Total Maximum Daily
Loads for Fecal Coliform for Rich Fork Creek and Hanby Cree, North Carolina. Final
Report.
Owen, Debra. NCDWQ. Personal communication. 2001.
SAS. 2004. V9.1.2, SAS Institute, Cary, NC.
TetraTech. 2004. Water Quality Data Review for High Rock Lake, North Carolina. Prepared for NC
Department of Environmental and Natural Resources.
Touchette, B. W., J. M. Burkholder and H. B. Glasgow. 2001. Distribution of American water willow
(Justicia americana L.) in the Narrows Reservoir. Center for Applied Aquatic Ecology. North
Carolina State University. Raleigh NC. 51 pp.
Wetzel, R.G. 2001. Limnology, Lake and River Ecosystems. Third Edition. Academic Press. San
Diego. 980 pp.
Yadkin Project Water Quality Monitoring Study 127 Normandeau Associates
Water Quality
Yadkin, Inc. 1999. Yadkin Project Shoreline Management (SMP). Volumes I and 2 for the Yadkin
Hydroelectric Project, FERC Project No. 2197.
Yadkin Project Water Quality Monitoring Study 128 Normandeau Associates