20070812 Ver 1_23 Sept 2006 Goldenrod Survey, Final Report_20080502

Alcoa Power Generating Inc.
Yadkin Division
Yadkin Project Relicensing (FERC No. 2197)
Yadkin River Goldenrod Survey
Final Study Report
September 2006
Table of Contents
Report Summary .................................................................................................... .......................3
1 Introduction ................................................................................................... .......................4
2 Background ................................................................................................... .......................4
3 Study Objectives ........................................................................................... .......................5
4 Study Area .................................................................................................... .......................6
4.1 Project Operations ................................................................................ .......................6
5 Study Methods .............................................................................................. .......................7
6 Study Results ................................................................................................ .......................8
7 Discussion and Conclusions ......................................................................... .....................14
8 Comment Summary ...................................................................................... .....................15
9 References ..................................................................................................... .....................16
Appendix 1- Yadkin River Goldenrod Survey Final Study Plan ..................... .....................17
Appendix 2 - Existing Yadkin River Goldenrod Locations ............................... .....................18
Appendix 3 - IHA Analysis Summary Statistics ................................................. .....................19
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Report Summary
Alcoa Power Generating Inc. (APGI) is the licensee for the four development Yadkin
Hydroelectric Project (Yadkin Project or Project). The current license expires in 2008 and APGI
filed a new license application with FERC in April 2006. As part of the relicensing process
APGI conducted studies of resources and issues of concern to state and federal agencies and
stakeholders. The Yadkin River Goldenrod report presents the results of an evaluation of Yadkin
River goldenrod (Solidago plumosa), below the Narrows and Falls dams.
This study was conducted in accordance with the Final Study Plan that was developed by APGI
in consultation with the Wetlands, Wildlife and Botanical Issue Advisory Group (IAG). The
primary objectives identified in the Final Study Plan were to characterize the current hydrologic
conditions at extant Yadkin River goldenrod populations, to compare the current hydrologic
regime at these locations to "unregulated" conditions, and to identify measures to improve
habitat conditions for the species.
Solidago plumosa (Yadkin River goldenrod) is endemic to the Yadkin River in North Carolina.
According to the U.S. Fish and Wildlife Service (USFWS, 2004), John Kunkell Small originally
described the plant from the Narrows Canyon and Falls area of the Yadkin River in 1894.
Subsequent to Small's original discovery of the plant, the Narrows and Falls dams were
constructed in the Narrows Canyon in 1917 and 1919, respectively. In 1994, Solidago plumosa
was rediscovered in two locations along the shorelines and in rock shoals below Narrows and
Falls dams. These sites remain the only known locations where this species currently exists.
Solidago plumosa is currently listed by the USFWS as a Federal Species of Concern (FSC). On
May 11, 2005, the USFWS proposed that Solidago plumosa be listed as a candidate for addition
to the List of Endangered and Threatened Plants species. The USFWS assigned the plant a
listing priority number of eight.
The study focused on several existing populations of Yadkin River goldenrod in the tailwater
areas below Narrows and Falls dams. The elevations of these representative plant locations were
measured and an analysis was done to determine the river flows at which each site would be
inundated. Results showed that the location of most of the Yadkin River goldenrod plants is
such that the plants are rarely directly affected by river flows or the scour related effects of river
flows. Of the 14 plant locations studied below Narrows and Falls dams, only three would be
expected to be directly affected by flows of less than 100,000 cfs, and no sites were found to be
inundated at flows of less than 10,000 cfs, the approximate hydraulic capacity of the
powerhouses.
These results demonstrate Yadkin River goldenrod does not require frequent inundation or
scouring to maintain viable habitat conditions. Instead, it appears that very infrequent inundation
may be an important habitat component. The results of the study also demonstrate that none of
the existing plant locations are in areas that are affected by generation flows. Inundation of all
plant sites below both Narrows and Falls dams occur at flows in excess of the hydraulic capacity
of the respective developments and so the plants are only affected during spill events outside the
control of APGI.
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I Introduction
Alcoa Power Generating Inc. (APGI) is the licensee for the Yadkin Hydroelectric Project
(Yadkin Projector Project). The Yadkin Project is managed and operated by APGI's Yadkin
Division and is currently licensed by the Federal Energy Regulatory Commission (FERC) as
Project No. 2197. This license expires in 2008 and APGI filed a new license application with
FERC in April 2006.
The Yadkin Project has four reservoirs, dams, and powerhouses (High Rock, Tuckertown,
Narrows, and Falls) located on a 38-mile stretch of the Yadkin River in central North Carolina.
The Project generates electricity to support the power needs of Alcoa's Badin Works, to support
its other aluminum operations, or is sold on the open market.
As part of the relicensing process, APGI prepared and distributed, in September 2002, an Initial
Consultation Document (ICD), which provides a general overview of the Project. Agencies,
municipalities, nor-governmental organizations and members of the public were given an
opportunity to review the ICD and identify information and studies that were needed to address
relicensing issues. To assist in the identification of issues and data or study needs, APGI formed
several Issue Advisory Groups (IAGs) to advise APGI on resource issues throughout the
relicensing process. The Wetlands, Wildlife, and Botanical IAG finalized the Study Plan for the
Yadkin River Goldenrod Survey in September 2004 (see Appendix 1).
2 Background
In a letter dated April 28, 2004, the U.S. Department of Interior, Fish and Wildlife Service
(USFWS) asked Yadkin, as part of the relicensing process, to evaluate the status of the Yadkin
River Goldenrod at the Narrows and Falls developments tailwaters and to assess potential
impacts to existing plant populations which might results from the continued operation of the
Yadkin Project. Subsequent to receiving that request, APGI worked with the Wetlands, Wildlife
and Botanical IAG to develop a study plan for this study. A final study plan (September 2004)
was distributed to the IAG on October 1, 2004.
Solidago plumosa (Yadkin River goldenrod) is endemic to the Yadkin River in North Carolina.
According to the U.S. Fish and Wildlife Service (USFWS, 2004), John Kunkell Small originally
described the plant from the Narrows Canyon and Falls area of the Yadkin River in 1894. There
is no other existing information to suggest that the species ever occurred in any other area other
than that described by Small (p. communication Wells, 2005). Subsequent to Small's original
discovery of the plant, the Narrows and Falls dams were constructed in the Narrows Canyon in
1917 and 1919, respectively. In 1994, Solidago plumosa was rediscovered in two locations
along the shorelines and in rock shoals below Narrows and Falls dams. These sites remain the
only known locations where this species currently exists.
Solidago plumosa is currently listed by the USFWS as a Federal Species of Concern (FSC). On
May 11, 2005, the USFWS proposed that Solidago plumosa be listed as a candidate for addition
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Final Study Report, September 2006 -4-
to the List of Endangered and Threatened Plants species. The USFWS assigned the plant a
listing priority number of eight.
Over the past several years, APGI, along with Progress Energy and the North Carolina Plant
Conservation Program have been working to develop management guidelines for this species.
However, the species' requirements for seed germination and seedling establishment are not
known. According to the USFWS, the species appears to persist in areas subjected to periodic
scouring of a velocity sufficient to prevent the establishment of other species without eliminating
already established goldenrod plants. At the same time, the species does not appear tolerant of
prolonged inundation since it does not occur in frequently flooded habitats.
In recent years, staff from the USFWS, the NC Plant Conservation Program, and the North
Carolina Zoological Park have been informally surveying plant locations and monitoring the
status of these plants. In August, October, and November 2004 representatives of the NC Plant
Conservation Program (Ms. Moni Bates) and the NC Zoological Park (Mr. Pete Diamond)
surveyed tributaries and the upper Yadkin River watershed for additional populations and
suitable habitat for Yadkin River goldenrod. A five-day survey of rock outcrop habitat in the
Yadkin River watershed did not identify any Yadkin River goldenrod populations in addition to
those identified by this study below Narrows and Falls dams in August 2004 (see Section 6).
Based on her evaluation of available habitat, Ms. Bates concluded that there are few "safe" sites
available for seedling establishment because adults and/or invasive species are already
established in the best sites. Ms. Bates recommended that the rock outcrop and adjacent habitat
below Narrows Dam be managed to control exotic plant species and that reintroduction efforts be
focused on the most suitable habitat noted during the survey, which is immediately above and
below Falls Dam. Also, given the low seedling and juvenile recruitment, Ms. Bates suggested
that propagated adults be used to establish new subpopulations. Regarding Project impacts to
existing plant populations, Ms. Bates concluded that high water releases from the dams may
temporarily inundate some of the plant populations and may cause the breakage of flowering
stems (Bates, 2005).
A draft study report was distributed to the Wetlands, Wildlife and Botanical IAG in January
2006 for review and comment. The only comments received on the draft were from the US Fish
and Wildlife Service (email dated 2/9/06). The USFWS commented that the study report should
include a comparison of hydrologic conditions under both regulated and unregulated flow
conditions using the Indicators of Hydrologic Alteration (IHA) methodology. In response to
those comments, IRA statistics have been included in the final report.
3 Study Objectives
As outlined in the final study plan, the objectives of this study are as follows:
¦ Characterize the current hydrologic conditions at extant (existing) Solidago plumosa
populations
¦ To the extent possible, compare the location of existing plants to where the plants had
been located prior to construction of the Narrows and Falls dams
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¦ Compare the current hydrologic regime at existing plant locations to Project inflow
conditions
¦ Identify measures to improve habitat conditions for the species
4 Study Area
The study area for this investigation is the tailwater areas located immediately downstream of the
Narrows and Falls dams and powerhouses. At Narrows, the study area includes both the
mainstem of the river directly downstream of the dam, and the spillway channel that joins the
mainstem river approximately 1,000 feet downstream of Narrows Dam. At Falls, the study area
is the main channel area immediately downstream of the Falls Dam and powerhouse.
4.1 Project Operations
Operation of the four Yadkin Project developments is coordinated by APGI to make the best use
of available water and to minimize spill. Generally, the Project is operated during peak hours to
maximize the economic value of the power produced. The High Rock Development is a storage
facility that is operated in a store and release mode. The Tuckertown and Falls developments are
essentially operated in a run-of-river mode. The Narrows Development is also generally
operated as a run-of-river facility. However, there is some storage available at Narrows that can
be used by APGI, as needed, during periods of very low stream flow to help maintain
downstream releases.
The flow being released downstream of each development during periods of generation is
generally governed by the amount of water available and the number of generating units being
operated at each facility. The maximum hydraulic capacities of the Narrows and Falls
developments are 10,000 cfs and 8,570 cfs, respectively. When river flows exceed the hydraulic
capacity of these developments, excess water is stored in the reservoir. Once the reservoir
reaches its normal full pool elevation, water in excess of the hydraulic capacities of the
generating units is passed downstream through spillway gates.
Narrows Dam consists of a main dam section and a bypass spillway section. The main dam
consists of a nor-overflow gravity section, a gate conrolled spillway section, and intake section,
a downstream powerhouse, and four steel penstocks. The bypass spillway section is comprised
of a nor overflow gravity section and a gate controlled spillway section. The spillway gates are
located in a section of the dam which is removed from the main dam. At Narrows Dam, gates
located on the spillway section are generally used to pass most high flow events. Only after the
hydraulic capacity of this gated section is neared, does APGI then utilize the spillway gates
located on the main section of the dam.
Falls Dam consists of a nor overflow gravity section, a gate controlled spillway section and an
integral intake/powerhouse section. The spillway section is approximately 525 feet long with 10
Stoney gates and two Tainter gates to release surplus water during high flow events.
At Narrows, when water is spilled, the spillway gates are used first for flows from 10,000 cfs up
to about 185,000 cfs. For flows higher than 185,000 cfs, APGI releases water through the
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Final Study Report, September 2006 -6-
Tainter gates on the main dam. At Falls, all spill is released through the gates on the main dam.
These gates are remotely operated, and are typically operated in this order: 4, 3, 2, 1.
5 Study Methods
As a first step in the study, information was collected on the current locations of Yadkin River
goldenrod in the two tailwater study areas. To do this, APGI enlisted the services of a staff
botanist with the North Carolina Plant Conservation Program. On August 5, 2004, Ms. Moni
Bates, a botanist recognized for her expertise with Solidago plumosa (Yadkin River goldenrod),
accompanied the APGI survey crews into the field for an initial reconnaissance of the plant
locations. During that site visit, all existing locations of Yadkin River goldenrod plants were
identified and described (see Appendix 2). Upon the recommendation of Ms. Bates, fourteen
(14) separate plant locations, twelve (12) in the Narrows tailwater area and two (2) in the Falls
tailwater area, were selected as representative locations for the study. Each of the twelve (12)
representative plant locations was clearly marked and GIS coordinates taken so the plant
locations could be relocated later.
On November 9, 2004 PB Power (PB) staff returned to the field to determine the elevation and
locations of these representative sites. Once the 14 representative plant locations were identified,
an optical level was set up at each site and the elevation in relation to the reservoir water surface
was measured. A GPS (GeoExplorer 3) instrument was used to determine the longitude and
latitude of the location of the elevation measurement. All generation was shut down while
elevations were being measured so the reservoir elevation would be constant. From the optical
level data and reservoir elevation, the elevation of the representative plant sites was calculated in
USGS datum.
Once elevations for each of the representative plant locations were established, PB Power
estimated the river flow at which each of the sites would be inundated based on a river flow
versus water elevation relationship developed from a backwater analysis between Falls Dam and
Narrows Dam.
After an inundation elevation for each plant location had been determined, PB Power reviewed
the hydrologic record for the Narrows and Falls developments to determine which plant locations
were likely to be inundated by flows resulting from current Project operations. To do this, PB
Power simulated existing Project operations using a version of the OASIS model that has been
developed to simulate operation of the Yadkin Project developments. The results of the model
simulation of existing operations at the Project provided PB Power with a 74 year record (1930 -
2003) of daily outflows from the Narrows and Falls developments. PB then used the OASIS
model to provide a simulation of river flows at the two study locations under simulated
"unregulated" conditions. Unregulated conditions were simulated by having the OASIS model
operate the Project reservoirs in strict run-of-river mode, where reservoirs levels were
maintained at full pond and as a result inflow equals outflow.
The resulting hydrologies for both existing and run-of-river flow conditions were then compared
to determine any differences in the two flow regimes in the ranges of flows that would be
expected to impact the representative plant locations. As a follow-up to initial evaluations of
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hydrologic conditions using flow duration curves and statistics, APGI had their instream flow
consultant Entrix work with PB Power to run anIHA analysis of the both the existing and run-
of-river flow conditions. The resulting IHA statistics are summarized in tables in Appendix 3.
6 Study Results
Table 6-1 and Table 6-2 summarize the status of existing Yadkin River goldenrod plant
populations observed by APGI in both tailwater areas in 2004. These tables provide a general
description of the plant location, the GPS coordinates of the location, and notes about the plant's
status as observed on August 5, 2004. The twelve (12) plant locations that were selected as
representative locations for further study are highlighted in Table 6-3.
Table 6-1 Summary of Yadkin River Goldenrod Plant Locations in the Narrows Development Tailwater Area
Site General Location GPS Coordinates Photograph/Notes
1 Base of Narrows Dam, Stanly County side N: 35 25' 08.5"
W: 80 05' 36.1
2 Base of Narrows Dam, Stanly County side N: 35 25' 08.3"
W: 80 05' 36.8"
3 Base of Narrows Dam, Stanly County side N: 35 25' 08.2" *Plants were beginning to flower
W: 80 05' 36.8"
4 Base of Narrows Dam, Stanly County side N: 35 25' 08.1"
W: 80 05' 36.4"
5 Just above bridge in the Narrows tailwater, N: 35 25' 05.6"
Stanl Count side W: 80 05' 32.7"
6 Just below bridge in the Narrows tailwater, N: 35 25' 04.7" *Invasive plants potentially
Stanly County side W: 80 05' 31.5" hindering growth of the Yadkin
River goldenrod here
7 Just below bridge in the Narrows tailwater, N: 35 25' 04.5"
Stanly County side W: 80 05' 30.6"
8 Just below bridge in the Narrows tailwater, N: 35 25' 06.3"
Montgomery County side W: 80 05' 29.4"
9 Just below bridge in the Narrows tailwater, N: 35 25' 06.3" *Fishermen and other
Montgomery County side W: 80 05' 29.6" recreationists impacting plants in
this area
10 Just below bridge in the Narrows tailwater, N: 35 25' 06.6" *Many invasive plants (Multiflora
Montgomery County side W: 80 05' 29.3" rose) in this area
11 Just below bridge in the Narrows tailwater, N: 35 25' 06.8" *Many invasive plants in this area
Montgomery County W: 80 05' 29.3"
12 Southeast of the peninsula in the Narrows N: 35 24' 48.0
tailwater, Montgomery Count side W: 80 5' 21.5
13 Narrows spillway, Montgomery County side N: 35 24' 47.9" *Moni Bates has transplanted
W: 80 05' 21.5" Yadkin River goldenrod in this
area
14 Narrows spillway, Montgomery County side N: 35 24' 47.7"
W: 80 05' 21.4"
15 Narrows spillway, Montgomery County side N: 35 24' 54.2" *Foot traffic in this area
W: 80 05' 19.5"
16 Narrows spillway, Montgomery County side N: 35 24' 54.3"
W: 80 05' 19.4"
17 Narrows spillway, Montgomery County side N: 35 24' 55.2"
W: 80 05' 19.7"
18 Narrows spillway, Montgomery County side N: 35 24' 55.6" *Significant plant populations,
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Final Study Report, September 2006 -8-
Site General Location GPS Coordinates Photograph/Notes
W: 80 05' 19.8" more sunlight, less competition
from invasives
19 Narrows spillway, Montgomery County side N: 35 24' 55.7"
W: 80 05' 19.5"
20 Narrows spillway, Montgomery County side N: 35 24' 56.2"
W: 80 05' 19.6"
21 Narrows spillway, Montgomery County side N: 35 24' 57.4"
W: 80 05' 20.2"
22 Narrows spillway, Montgomery County side N: 35 24' 57.8"
W: 80 5' 20.3"
23 Island below Narrows tailwater and spillway N: 35 24' 46.5"
W: 80 5' 23.7"
24 Island below Narrows tailwater and spillway N: 35 24' 46.4 ,
W: 80 5'23.3"
Table 6-2 Summary of Yadkin River Goldenrod Plant Locations in the Falls Development Tailwater Area
Site General Location GPS Coordinates Photograph/Notes
No.
1 Lake Tillery/Falls tailwater, rock outcropping N: 35 23' 24.5"
Stanl Count side W: 80 4' 10.2"
2 Immediately below Falls Dam in the Falls N: 35 23' 42.0" *Not able to access plant due to
tailwater W: 80 4' 27.0" location
Table 6-3 provides a summary of each of the fourteen (14) representative plant locations selected
for the study. The table also provides the plant elevations (Yadkin datum) and the estimated
river flow at which the plant location becomes wetted.
Table 6-3 Summary of Representative Plant Location Information
Representative
Plant Site No. General Location Plant Elevation
(USGS) Estimated Flow at
Which Plant
Location is
Wetted
Narrows Tailwater
Population I Narrows tailwater, downstream of main
Site 1 dam on right bank. 338.5 210,000 cfs
Site 2* >338.57 >210,000 cfs
Site 3* >338.57 >210,000 cfs
Site 4* >338.57 >210,000 cfs
Population 2 Narrows tailwater, downstream of
Site 7 powerhouse bridge, on left and right 337.0 190,000 cfs
Site 9 banks 339.1 >190,000 cfs
Site 10 343.2 >190,000 cfs
Site 11 347.2 >190,000 cfs
Population 3 Narrows tailwater just downstream of
Site 18 bypass spillway, on the left bank 333.7 16,000 cfs
Site 19 339.5 110,000 cfs
Population 4 Narrows tailwater, downstream of
Site 23 powerhouse bridge on right bank 340.0 280,000 cfs
Site 24 335.3 150,000 cfs
Falls Tailwater
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Population 5 Falls tailwater, downstream of Falls
Site 2 dam, at approximate center of gate
section 278.3* 11,000
Population 6 Falls tailwater, 2,300 ft downstream of
Site 1 dam on right bank rock outcropping 282.9 74,000 cfs
I hxact elevations of plants sites L, 3 and 4 tot Population 1 were not taken as tiney were notably tugtier Man bite 1.
As shown, the elevation of the representative plant locations in the Narrows tailwater range
between 333.7 ft and 347.2 ft (USGS ). The estimated flow at which each plant location would
become wetted is estimated to range from a low of 16,000 cfs to a high of 280,000 cfs. Plant site
18 (Population 3) which is located in the Narrows tailwater, on the left bank, just downstream of
the confluence of the bypass spillway, is the plant location that is expected to be wetted at the
lowest flow (16,000 cfs), and therefore is the location that is most frequently affected by flows
from the Narrows Dam. However, it is important to note that none of the representative plant
populations would be expected to become wetted at flows of 10,000 cfs, or less. Therefore, the
current plant locations are only impacted by spill events that exceed the hydraulic capacity of the
powerhouse, and therefore, are beyond the control of APGI.
In the Falls tailwater, the elevation of the two plant populations range between 178.3 ft and 282.9
ft (USGS). The estimated flows at which the plants at these two locations would become wetted
are 11,000 cfs (Site 2), and 74,000 cfs (Site 1), respectively. Again, since the hydraulic capacity
of the Falls turbines is approximately 8,570 cfs, the plants at these locations would only be
affected by spill events that are beyond the control of APGI.
Using the OASIS model, simulated river flows at Narrows Dam under existing Project operating
and run-of-river (simulated "unregulated') conditions were developed for the period 1930-2003.
Flow duration curves for the existing and run-of-river condition flows at Narrows are provided in
Figure 6-1 and Figure 6-2. As shown, under existing conditions, flows exceed the lowest flow
value at which a Yadkin River goldenrod plant site located in the Narrows tailwater is wetted
(16,000 cfs at Site 18) approximately 2% of the time. By comparison, flows under run-of-river
(simulated "unregulated") conditions would be expected to exceed 16,000 cfs approximately 3%
of the time.
For Falls, using the same Narrows flow duration curves 1, under existing conditions, flows exceed
the lowest flow value at which a Yadkin River goldenrod plant site located in the Falls tailwater
is wetted (11,000 cfs, Site 1) approximately 4% of the time. Under run-of-river (simulated
"unregulated") conditions, flows would be expected to exceed 11,000 cfs approximately 7% of
the time.
1 Simulated flows at Narrows Dam were also used as the simulated flows at Falls Dam, since there is virtually no
intervening drainage between the two dams.
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Figure 6-1 Narrows Flow Duration Curve (Existing Conditions)
Flow Duration Curve
Narrows Outflow-Existing Conditions
40000
35000
30000
25000
0 20000
V3
0 15000
10000
5000
0
0% 20% 40% 60% 80% 100%
Percent Exceedence
I - Series 11
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Final Study Report, September 2006 - 11 -
Figure 6-2 Narrows Flow Duration Curve (Run-of River)
Flow Duration Curve
Narrows Outflow-Run of River
40000
35000
30000
25000
6 20000
V3
0 15000
10000
5000
0
0% 20% 40% 60% 80% 100%
Percent Exceedence
P Series1
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Final Study Report, September 2006 -12-
A more detailed look at differences in the existing and run-of-river (simulated "unregulated")
flow data sets was made by reviewing both of the 73 year records and determining the number of
high flow events where flow exceeded 16,000 cfs and 11,000 cfs, respectively. Table 6-4 shows
the results of that comparison. Specifically the table summarizes the total number of flow events
where flows exceeded 11,000 cfs and 16,000 cfs during the period 1930-2003, as well as the
annual average number of high flow events, under both existing and unregulated scenarios.
As shown in Table 6-4, during the period of record 1930-2003, under existing operations, there
are an average of three high flow events each year during which flows exceeded 16,000 cfs
under existing Project operations. Under the simulated unregulated condition, the average
annual number of events where flows exceed 16,000 cfs would be expected to be six. For the
same 73 year period of record, there are on average four events each year during which flows
exceed 11,000 cfs under existing conditions, and 10 events expected each year under
"unregulated" conditions.
Table 6-4 Summary of High Flow Events that Exceed 11,000 cfs and 16,000 cfs at Narrows Dam
Existing Unregulated
Total Number of Flow Events 1930-2003 that Exceed 92 221
16,000 cfs
Average Annual Number of Flow Events that Exceed 3 6
16,000 cfs
Total Number of Flow Events 1930-2003 that Exceed 143 360
11,000 cfs
Average Annual Number of Flow Events that Exceed 4 10
11,000 cfs
The two flow hydrologies were also evaluated using the Indicators of Hydrologic Alteration
(IHA) software (TNC, 1997). Both parametric and non-parametric statistics were run on both
the existing conditions and the simulated unregulated (run-of-river) scenarios individually.
Statistics were run on water years (Oct 1 through Sept 30) to keep wet and dry portions of the
year together. To avoid having the IHA program interpolate data, only complete water years
within the period of record (WYs 1931-2003) were used.
All the data was put into a "combined" format that allows direct comparison of the two flow sets.
To do this, the existing condition flow data set was moved forward in time to follow the
simulated run-of-river (unregulated) data set. Because of the way the IHA program operates, it
was also necessary to insert a couple of years of blank data to match up the sequence of leap
years. The summary tables provided in Appendix 3 contain both parametric and parametric
statistics for these two hydrologies. The tables also contain the percent difference between the
unregulated and existing conditions periods for each parameter.2
2 When comparing the IHA run results it was noted that there is a difference on the SCO sheet in the calculated
Mean Flow between the "combined" run and the individual runs. These are both different than the mean that would
be calculated for the same period in Excel. Entrix contacted Tom Fitzhugh of TNC about this difference and TNC
acknowledged that the difference is due to a bug in the way the mean annual flow is calculated. The difference is
very small (less than 0.2 percent).
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Final Study Report, September 2006 -13 -
7 Discussion and Conclusions
Results of this study demonstrate several important ideas with respect to the effect of Project
operations, and resulting river flows, on the existing Yadkin River goldenrod population. First,
the location of most of the Yadkin River goldenrod plants is such that the plants are rarely
directly affected by river flows or the scour related effects of river flows. Of the 12
representative plant sites examined below Narrows Dam, only one was found to be located at an
elevation that would result in inundation at a flow of less than 100,000 cfs. The one site that
would be affected at a flow of less than 100,000 cfs is Site 18 which would be inundated at flows
in excess of 16,000 cfs. The two representative plant locations examined downstream of Falls
Dam were found to be located at an elevation that would result in inundation at flows of 74,000
cfs and 11,000 cfs. Thus, of the 14 plant locations studied in detail, only three would be
expected to be directly affected by flows of less than 100,000 cfs. This result suggests that the
Yadkin River goldenrod does not require frequent inundation or scouring to maintain viable
habitat conditions. Instead, it appears that very infrequent inundation may be an important
habitat component. If so, it may be that the more limited number of plants found below Falls
Dam, is due to a limitation on suitable growing sites that are at a high enough elevation to
prevent more frequent inundation and scour.
The results of the study also demonstrate that none of the existing plant locations are in areas that
are affected by generation flows. Inundation of all plant sites below both Narrows and Falls
dams occur at flows in excess of the hydraulic capacity of the respective developments and so
the plants are only affected during spill events outside the control of APGI.
Finally, results of the flow duration analysis suggest that existing Project operations, as
compared to simulated "run-of-river" operations, have reduced the average annual frequency of
some high flow events. This effect is a result of the operation of High Rock Reservoir, the
primary storage facility on the river. Typically, High Rock is operated with an average winter
drawdown of 12 ft, which allows APGI to capture some high flow events during the winter and
spring. Over the years, this operation has, on average, reduced the annual number of high flow
events at which some Yadkin River goldenrod plant locations may be inundated. What is not
clear, however, is whether the reduction in the number of high flow events has had a positive or
negative effect on the Yadkin River goldenrod population. Since the current location of the
plants suggest that they prefer sites that are very infrequently inundated, it seems likely that the
reduction in the number of high flow events, as a result of storage operations at High Rock, may
have created additional habitat for the Yadkin River goldenrod in the Narrows and Falls tailwater
areas by allowing plants to colonize lower elevation sites that may be less frequently inundated
by high flow events than they would be under "unregulated" conditions. Even if this were not
the case, the existing population of Yadkin River goldenrod has adapted to the current operation
of the Yadkin Project, and would not be expected to be adversely impacted by the continued
operation of the Project, under existing operating conditions. However, any significant changes
in the operation of High Rock as a storage reservoir that would result in an increase in the
frequency of spill events could have an impact on the existing Yadkin River goldenrod
populations.
Yadkin River Goldenrod Survey
Final Study Report, September 2006 -14-
The results of the IHA analysis are summarized in Tables 1 and 2 in Appendix 3 and provide a
more detailed comparison of the two hydrologic conditions (existing conditions and
unregulated). Although the IHA analysis does not specifically allow an examination of the
frequency of high flow events in excess of 11,000 and 16,000 cfs (the critical inundation flows),
examination of the maximum flow exceeded for 1, 7, 30, and 90 days provides a good
comparison of the frequency of the high flow events under the two hydrologic scenarios.
8 Comment Summary
Copies of the Yadkin River Goldenrod Survey Draft Report were distributed to the Wetlands,
Wildlife and Botanical Issue Advisory Group (IAG) in January 2006. Comments on the draft
report were solicited from IAG members. The table below is a summary of the comments
received and responses to the comments.
Source of Comment Comment Response
US Fish and Wildlife The Service [USFWS] is APGI has conducted the requested
Service, email dated concerned that the Yadkin IHA analysis comparing boththe
February 9, 2006 River goldenrod is simulated unregulated (run-of-
threatened more by river) hydrology with the existing
alterations in timing, condition hydrology. IHA
duration, and/or frequency statistics (both parametric and non
of high flow events than in parametric) are summarized in
alterations of more periodic tables in Appendix 3.
low to moderate velocity
flows. An IHA analysis
would facilitate a more
robust examination of this
possibility.
Yadkin River Goldenrod Survey
Final Study Report, September 2006 - 15 -
9 References
Bates, Moni. 2005. Range Expansion Survey and Monitoring of Solidago plumosa (Yadkin
River Goldenrod). US Fish and Wildlife Service. February 15, 2005.
Pardue, Dr. Garland. US Fish and Wildlife Service. April 28, 2004 personal communication
(letter).
The Nature Conservancy. Indicators of Hydrologic Alteration User's Manual. January, 1997.
Wells, Carolyn L. Ph.D. US Fish and Wildlife Service. August 18, 2005 personal communication
(letter).
Yadkin River Goldenrod Survey
Final Study Report, September 2006 -16-
Appendix 1- Yadkin River Goldenrod Survey Final Study Plan
Yadkin River Goldenrod Survey
Final Study Report, September 2006 - 17 -
Yadkin Project (FERC No. 2197)
Yadkin River Goldenrod (Solidagoplumosa) Survey
Final Study Plan
September 2004
Background
Alcoa Power Generating Inc. (APGI) is the licensee for the Yadkin Hydroelectric Project. The
Yadkin Project is currently licensed by the Federal Energy Regulatory Commission (FERC) as
Project No. 2197. This license expires in 2008 and APGI must file a new license application with
FERC on or before April 30, 2006 to continue operation of the Project.
The Yadkin Project consists of four reservoirs, dams, and powerhouses (High Rock, Tuckertown,
Narrows, and Falls) located on a 38-mile stretch of the Yadkin River in central North Carolina.
The Project generates electricity to support the power needs of Alcoa's Badin Works, to support
its other aluminum operations, or is sold on the open market.
As part of the relicensing process, APGI prepared and distributed, in September 2002, an Initial
Consultation Document (ICD), which provides a general overview of the Project. Agencies,
municipalities, non-governmental organizations and members of the public were given an
opportunity to review the ICD and identify information and studies that are needed to address
relicensing issues. To further assist in the identification of issues and data/study needs, APGI
has formed several Issue Advisory Groups (IAGs) to advise APGI on resource issues throughout
the relicensing process.
In a letter dated April 28, 2004, the U.S. Department of Interior, Fish and Wildlife Service
(USFWS) requested as part of the FERC relicensing process that Yadkin conduct an evaluation of
certain aspects of a rare plant species, Yadkin River goldenrod (Solidago plumosa) that is known
to exist in the tailwater area of the Narrows development.
In response to this study request, in August 2004, APGI prepared and distributed a draft study
plan to the Wetlands, Wildlife and Botanical IAG for review and comment. Comments on the
draft study plan were received from the North Carolina Wildlife Resources Commission (8/27/04
email from Todd Ewing). NCWRC comments focused on three areas: 1) expanding the study
plan to evaluate hydrologic conditions at extant as well as existing Solidago Plumosa locations; 2)
clarifying assumptions that would be made regarding the steady-state reservoir elevation
conditions (normal full pool) that would be assumed for all hydraulic modeling work done in the
Narrows and Falls tailwater areas; and 3) clarify how the unregulated and regulated hydrologic
conditions would be evaluated absent detailed knowledge about the velocity and depth conditions
produced at specific plant locations under a range of flow conditions. APGI has addressed these
comments in this revised final study plan.
Overview
Solidago plumosa is endemic to the Yadkin River in North Carolina. According to the USFWS,
John Kunkell Small originally described the plant from the Narrows Canyon and Falls area of the
Yadkin River in 1894. Subsequent to Small's original discovery of the plant the Narrows and
Falls Dam were constructed in the Narrows Canyon area in 1917 and 1919, respectively. In
1994, Solidago plumosa was rediscovered in two locations along the shorelines and in rock shoals
Yadkin River Goldenrod Survey
Final Study Plan, September 2004
below Narrows and Falls dams. These sites remain the only known locations where this species
currently exists.
Sohdago plumosa is currently listed by the USFWS as a Federal Species of Concern (FSC). Over
the past several years, APGI, along with Progress Energy and the North Carolina Plant
Conservation Program have been working to develop management guidance for this species.
However, the species' requirements for seed germination and seedling establishment are not
known (USFWS, 2004). According to the USFWS, the species appears to persist in areas
subjected to periodic scouring of a velocity sufficient to prevent the establishment of other
species without eliminating already established goldenrod plants. At the same time, the species
does not appear tolerant of prolonged inundation since it does not occur in frequently flooded
habitats.
Issues
In their letter of April 28, 2004, the USFWS indicated that additional information is needed in
order to evaluate the status of the Yadkin River goldenrod and to assess potential impacts to the
existing plant population which might result from the continued operation of the Yadkin Project
Specifically, the USFWS recommended that Yadkin conduct a study that would examine the
relationship between the existing population(s) of Sohdago plumosa and the operation of the
Yadkin Project.
Objectives
Based primarily on the recommendations of the USFWS, the objectives of this study are to:
¦ Characterize the current hydrologic conditions at extant (existing) Sohdago plumosa
populations
¦ To the extent possible, compare the location of existing plants to where the plants had been
located prior to construction of the Narrows and Falls dams
¦ Compare the current hydrologic regime at existing plant locations to Project (High Rock)
inflow conditions (which would be used to represent "unregulated" river flows)
¦ Identify measures to improve habitat conditions for the species.
Geographic Extent
The study area will include the Narrows and Falls tailwater areas. For purposes of this study, the
Falls tailwater area will be considered the area that is within the hydraulic influence of discharges
from the Falls Powerhouse under a normal range (within 2 feet of full) of Tillery Reservoir water
levels.
Methods
This study will evaluate unregulated' and current (regulated) hydrologic conditions in the vicinity
of known locations of Sohdago plumosa. The primary focus of the study will be on the existing
' For purposes of this study, unregulated hydrologic conditions will be the flow that would occur with all
existing Yadkin Project developments in place, operating in a run-of-river (outflow equals inflow on a daily
basis) mode.
Yadkin River Goldenrod Survey
Final Study Plan, September 2004 2
populations, but the study will also consider the historic location of Solidago plumose, based on
available records of historic of plant locations. APGI will contact the USFWS to obtain
information that it has compiled on the historic locations of the plants. Historic plant locations
will be recorded in APGI's GIS database and located on maps to be included in the study report.
APGI will also locate existing plants and select representative sites where Solidago plumosa is
currently growing in the Narrows and Falls tailwater areas. To locate existing plants, Yadkin will
enlist the assistance of a qualified botanist with the North Carolina Plant Conservation Program
(NCPCP). GPS coordinates for all existing plant locations will be measured and recorded by PB
Power and APGI staff and mapped on USGS quad sheets. The locations will also be incorporated
into the Yadkin GIS database and located on maps in the study report.
Once the plants have been located, Yadkin and PB Power will meet on site with the NCPCP
botanist and agency representatives to select up to 5 representative plant locations in each of the
tailwater areas (for a maximum of 10 total). Transects will be established at each of the plant
locations, and the elevation of the plants growing along each transect will be established.
After transects have been established, PB Power will develop cross-sectional data, including
water depth if appropriate, for each, and will utilize the cross-sections to construct a simple
hydraulic model of the Narrows and Falls tailwaters. The hydraulic model will allow PB Power
to simulate changes in hydraulic conditions (water surface elevation, depth and velocity) at the
representative locations under a range of discharge conditions. Hydraulic model results will be
used to determine the flows at which the representative existing Solidago plumosa plants are
inundated. Since the elevation of the reservoir downstream of the tailwater area being modeled,
can affect the water surface elevation of the tailwaters, for purposes of the hydraulic modeling
proposed for this study a steady state downstream reservoir elevation will be assumed. Since
Falls and Tillery reservoirs normally fluctuate less than 3 feet daily and since normal full pool
represents the most typical elevation that would occur during high flow events that have the
greatest potential to inundate the plants, a normal full pool condition will be assumed for Tillery
and Falls reservoirs for all hydraulic modeling of the Falls and Narrows tailwaters. A minimum
threshold flow for inundation of the existing plants will be established for each of the
representative plant locations.
Once a minimum threshold flow has been established for each of the representative plant
locations, PB Power will evaluate the difference in unregulated and regulated flow conditions at
those sites. Specifically, PB Power will utilize the reconstructed "unregulated" and "regulated"
USGS gage based 75-year flow datasets developed for the OASIS model to consider the historic
hydrologic conditions at the representative plant locations.2 To do this an IHA (Indicators of
Hydraulic Alteration) analysis of both the unregulated and regulated long-term (75 year) flow
conditions will be conducted. Results of the IHA analysis will provide statistics on flow
conditions in the two tailwater areas which can be used to evaluate differences in the magnitude,
frequency and duration of flow conditions between the unregulated and regulated conditions on
existing populations of Solidago plumosa.
2 Unregulated and regulated flow datasets have been constructed for the Yadkin River utilizing historic
USGS gage data. The resulting datasets will be utilized in the OASIS model.
Yadkin River Goldenrod Survey
Final Study Plan, September 2004 3
Reporting
Results of the study will be provided in a draft study report. Once completed the draft study
report will be distributed to the Wetlands, Wildlife and Botanical IAG for review and comment.
IAG comments will be address and final study report prepared.
Schedule
Identification and location of Sohdago plumosa plants and selection of representative plant sites
and transects will be completed during the 2004 growing season. Hydraulic model development
and IHA analysis will be completed during the fall and winter of 2004. It is anticipated that a
draft report will be completed in the first quarter of 2005.
Yadkin River Goldenrod Survey
Final Study Plan, September 2004 4
Appendix 2 - Existing Yadkin River Goldenrod Locations
Yadkin River Goldenrod Survey
Final Study Report, September 2006 - 18 -

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Appendix 3 - IHA Analysis Summary Statistics
Yadkin River Goldenrod Survey
Final Study Report, September 2006 -19 -
IHA Table 1
Yadkin River Combined Non Parametric Statistics
Combined Unregulated (Run of River) and Existing Conditions Run
Yadkin River Combined Parametric -Unregulated Run of River) vs Existing Canditians
Watershed area
Mean annual flaw
Mean flaw?area
Annual C. V.
Flaw predictability
Canstancy?predictability
°/o of floods in 60d period
Flaad-free season
Parameter Group # 1
October
November
December
January
February
March
April
May
June
July
August
September
Mean ?°/off change
Parameter Group #2
1-day minimum
3-day minimum
7-day minimum
30-day minimum
90-day minimum
1-day maxi mu m
3-day maxi mu m
7-day maxi mu m
30-day maximum
90-day maximum
Number of zero days
Base flaw
Mean ?°/off change
Parameter Group #3
Date of minimum
Date of maxi mu m
Mean ?°/off change
Parameter Group #4
Law pulse count
Lawpulse duration
High pulse count
High pulse duration
Law Pulse Threshold
High Pulse Level
Mean ?°/off change
Unregulated Existing Canditians
1 1
5142 5156
5142 5156
1.16 1.04
0.47 0.43
0.84 0.83
0.31 0.31
2 6
COEFF. DEVIATION
MEANS of VAR. FACTOR DEV, of C.V.
Unregulated Existing Unregulated Existing Magnitude °/o Magnitude °/o
3785 3984 0.911 0.8122 199.1 5.259 -0.0988 -10.85
3848 4186 0.6164 0.5018 337.2 8.761 -0.1146 -18.59
5030 4826 0.4778 0.447 -203.8 -4.051 -0.03073 -6.432
6579 6358 0.5639 0.5198 -221.3 -3.363 -0.04407 -7.815
7382 7139 0.4457 0.4253 -243.5 -3.299 -0.02034 -4.563
8191 8081 0.4667 0.4512 -110 -1.343 -0.01542 -3.304
7206 6866 0.5034 0.5873 -340.4 -4.723 0.08383 16.65
5188 5071 0.4703 0.4955 -116.5 -2.246 0.02522 5.363
4326 4312 0.5502 0.5484 -13.77 -0.3184 -0.001776 -0.3228
3574 3660 0.518 0.4913 86.63 2.424 -0.02669 -5.152
3647 4003 0.6231 0.5777 356.1 9J65 -0.04541 -7.288
3306 3501 0.7436 0.6878 195 5.898 -0.05586 -7.512
4.3 7.8
1042 0 0.5118 0 -1042 -100 -0.5118 -100
1186 601.8 0.4186 0.2484 -583.7 -49.24 -0.1701 -40.65
1302 1506 0.4003 0.3135 204.6 15.72 -0.08686 -21.7
1596 1734 0.3789 0.3257 138.3 8.668 -0.05318 -14.04
2216 2495 0.3572 0.3154 279.2 12.6 -0.04181 -11.71
50400 45610 0.4682 0.5893 -4798 -9.519 0.1211 25.87
37970 32020 0.4705 0.5848 -5953 -15.68 0.1143 24.29
23510 20670 0.4229 0.481 -2840 -12.08 0.05804 13.72
12370 11890 0.3585 0.3572 -479.5 -3.877 -0.00127 -0.3543
8757 8540 0.3208 0.3282 -216.3 -2.471 0.007348 2.29
0.3699 47.15 7.315 0.3496 46.78 12650 -6.965 -95.22
0.2537 0.3018 0.3176 0.2755 0.04813 18.97 -0.04208 -13.25
1075 30.3
260 283.1 0.1041 0.0447 23.1 12.62 -0.05941 -57.06
62.53 81.52 0.2421 0.2335 18.99 10.38 -0.008641 -3.569
11.5 30.3
11.19 36.71 0.5555 0.2144 25.52 228 -0.3412 -61.41
7.806 3.424 0.5606 0.7623 -4.382 -56.14 0.2017 35.98
10.12 4.521 0.5127 0.7699 -5.603 -55.35 0.2572 50.16
2.471 2.812 0.2695 0.373 0.3412 13.81 0.1035 38.41
2300
11140
88.3
46.5
Yadkin River Combined Parametric -Unregulated Run of River) vs Existing Conditions
COEFF. DEVIATION
MEANS of VAR. FACTOR DEV. of C.V.
Unregulated Existing Unregulated Existing Magnitude % Magnitude
Parameter Group #5
Rise rate 1981 2568 0.3852 0.2471 587.1 29.63 -0.1382 -35.86
Fall rate -1185 -1872 -0.4015 -0.1885 -687.1 57.98 0.213 -53.05
Number of reversals 143.6 141.5 0.07333 0.08871 -2.082 -1.45 0.01538 20.97
Mean ?°/off change 29.7 36.6
EFC Low Flows
October Law Flow 2442 3280 0.3529 0.2654 837.5 34.3 -0.08749 -24J9
November Law Flow 2815 3930 0.3486 0.251 1114 39.58 -0.09757 -27.99
December Law Flow 3371 3761 0.3072 0.2692 389.3 11.55 -0.038 -12.37
January Low Flaw 3852 3773 0.2688 0.2598 -78.74 -2.044 -0.008925 -3.321
February Law Flow 4100 3480 0.2291 0.3042 -619.2 -15.1 0.07509 32.77
March Low Flaw 4460 3518 0.2037 0.3045 -942.8 -21.14 0.1009 49.52
April Low Flow 4071 2530 0.2378 0.2934 -1541 -37.86 0.05552 23.34
May Law Flow 3630 2771 0.2991 0.2845 -859.1 -23.67 -0.01459 -4.878
June Low Flaw 3182 2550 0.3067 0.2461 -632.2 -19.87 -0.06061 -19J6
July Low Flow 2730 2591 0.2638 0.208 -139.7 -5.118 -0.05575 -21.14
August Law Flow 2560 3181 0.2494 0.2535 620.9 24.25 0.004116 1.65
September Law Flow 2358 3093 0.2647 0.2392 735.7 31.2 -0.02553 -9.645
EFC Parameters
Extreme law peak 1034 122.4 0.2605 0.5803 -912.1 -88.17 0.3198 122.8
Extreme law duration 4.411 1.893 0.7296 0.115 -2.518 -57.08 -0.6146 -84.24
Extreme law timing 149.4 219.1 0.1865 0.2646 69.61 38.04 0.07814 41.9
Extreme low freq. 4.178 35.08 1.169 0.2431 30.9 739.7 -0.9263 -79.21
High flaw peak 11050 7791 0.2188 0.1643 -3255 -29.47 -0.05446 -24.89
High flow duration 5.431 5.943 0.377 0.323 0.5118 9.424 -0.05406 -14.34
High flow timing 160 123 0.2319 0.1225 37.03 20.23 -0.1094 -47.17
High flow frequency 19.22 24.45 0.2419 0.3496 5.233 27.23 0.1076 44.49
High flaw rise rate 3447 3568 0.2456 0.1734 121.4 3.521 -0.07214 -29.37
High flaw fall rate -1764 -2434 -0.1872 -0.1607 -669.3 37.93 0.02654 -14.17
Small Flaad peak 59290 60780 0.165 0.1806 1485 2.504 0.01562 9.455
Small Flood duration 30.73 49.91 0.8333 0.6551 19.18 62.41 -0.1783 -21.39
Small Flaad timing 75.68 74.74 0.05617 0.06191 0.9396 0.5134 0.005734 10.21
Small Flood freq. 0.6301 0.4795 1.198 1.351 -0.1507 -23.91 0.1535 12.81
Small Flaad riserate 11570 13900 0.749 1.157 2337 20.2 0.408 54.48
Small Flood fallrate -5071 -2408 -0.7913 -0.4348 2663 -52.51 0.3565 -45.05
Large flood peak 99790 99790 0.1129 0.1129 0 0 0.00 0.00
Large flood duration 22.71 44.29 0.8097 0.6426 21.57 94.97 -0.1671 -20.63
Large flood timing 73 73 0.06856 0.06856 0 0 0.00 0.00
Large flood freq. 0.09589 0.09589 3.092 3.092 0 0 0.00 0.00
Large flood rise 17170 26520 0.454 0.7562 9352 54.46 0.3021 66.54
Large flood fall -9555 -4168 -0.4988 -0.7901 5387 -56.38 -0.2913 58.39
Flow level to begin a high flow event is 5758.000
Flow level to end a high flaw event is 3654.000
Flow level to begin an extreme low flow is 1350.000
IHA Table 2
Yadkin River Combined Non Parametric Statistics
Combined Unregulated (Run of River) and Existing Conditions Run
Yadkin River Combined Nan Parametric -Unregulated (Run of River) vs Existing Conditions
Unregulated Existing Conditions
Watershed area 1 1
Mean annual flaw 5142 5156
Mean flaw?area 5142 5156
Annual C. V. 0.41 0.54
Flaw predictability 0.47 0.43
Canstancy?predictability 0.84 0.83
°/o of floods in 60d period 0.22 0.22
Flaad-free season 0 0
COEFF. DEVIATION SIGNIFICANCE
MEDIANS of DISP. FACTOR COUNT
Unregulated Existing Unregulated Existing Medians C.D. Medians C.D.
Parameter Group #1
October 2000 3014 0.8333 0.9939 0.507 0.1928 0.00 0.3964
November 2585 4127 0.7697 0.5872 0.5966 0.2371 0.00 0.2923
December 3612 4893 0.6863 0.6631 0.3547 0.03385 0.002002 0.8689
January 4683 6494 0.5631 0.4426 0.3867 0.2139 0.00 0.1562
February 5160 7311 0.5437 0.2698 0.4168 0.5037 0.00 0.006006
March 5757 7600 0.6172 0.4442 0.3201 0.2802 0.00 0.2222
April 4839 6884 0.6605 1.029 0.4226 0.5586 0.005005 0.04605
May 3806 5275 0.7578 0.9745 0.386 0.286 0.002002 0.1411
June 3369 3304 0.5597 1.094 0.01944 0.9555 0.8629 0.00
July 2791 2254 0.5502 1.152 0.1924 1.094 0.1161 0.002002
August 2453 4091 0.6372 0.5979 0.6678 0.06165 0.00 0.5856
September 2087 3045 0.6497 0.5232 0.459 0.1948 0.00 0.3353
Parameter Group #2
1-day minimum 1024 0 0.769 0 1 1 0.00 0.00
3-day minimum 1183 653.3 0.6432 0.1209 0.4476 0.812 0.00 0.07808
7-day minimum 1331 1500 0.6005 0.3643 0.1269 0.3933 0.04204 0.04204
30-day minimum 1655 1743 0.5468 0.4261 0.05332 0.2207 0.3774 0.2803
90-day minimum 2148 2476 0.4863 0.4307 0.1524 0.1142 0.03403 0.5275
1-day maximum 43830 42390 0.7054 0.9107 0.03292 0.291 0.5686 0.1201
3-day maximum 36040 28450 0.6234 0.8711 0.2106 0.3974 0.08308 0.08108
7-day maximum 22230 18610 0.5788 0.6817 0.163 0.1778 0.1592 0.4244
30-day maximum 11930 11440 0.5066 0.5146 0.0415 0.01581 OJ187 0.9229
90-day maximum 8708 8509 0.4714 0.4906 0.02276 0.04093 0.8018 0.8168
Number of zero days 0 46 0 0.5217 0.00 0.00
Base flaw 0.2605 0.3017 0.3991 0.3653 0.1582 0.08464 0.003003 0.7087
Parameter Group #3
Date of minimum 265 278 0.1243 0.01093 0.07104 0.9121 0.00 0.08408
Date of maxi mu m 62 82 0.2281 0.2527 0.1093 0.1078 0.1622 0.6777
Parameter Group #4
Law pulse count 11 37 0.7273 0.2703 2.364 0.6284 0.00 0.008008
Law pulse duration 4 2 0.6875 0 0.5 1 0.00 0.007007
High pulse count 17 20 0.4412 0.55 0.1765 0.2467 0.006006 0.2743
High pulse duration 3 5 0.5 0 0.6667 1 0.00 0.003003
Law Pulse Threshold 2300
High Pulse Level 5753
Yadkin River Combined Non Parametric -Unregulated (Run of River} vs Existing Conditions
COEFF. DEVIATION SIGNIFICANCE
MEDIANS of DISP. FACTOR COUNT
Unregulated Existing Unregulated Existing Medians C.D. Medians C.D.
Parameter Group #5
Rise rate 451 864 0.622 0.7685 0.9157 0.2357 0.00 0.2492
Fall rate -292 -517 -0.4041 -0.7838 0.7705 0.9397 0.00 0.006006
Number of reversals 145 142 0.1138 0.1303 0.02069 0.1449 0.3133 0.4535
EFC Low flaws
October Law Flow 1978 2915 0.4593 0.4661 0.4736 0.01484 0.00 0.953
November Law Flow 2439 4023 0.5282 0.3759 0.6494 0.2884 0.00 0.08609
December Law Flow 3105 3653 0.5323 0.473 0.1767 0.1115 0.04104 0.6245
January Low Flaw 3733 3679 0.4541 0.4975 0.01447 0.09564 0.9349 0.6176
February Low Flow 4229 3331 0.3542 0.5056 0.2125 0.4274 0.007007 0.01301
March Low Flaw 4530 3635 0.3622 0.5453 0.1977 0.5057 0.006006 0.02503
April Low Flaw 3991 2100 0.4008 0.08137 0.4738 0.797 0.001001 0.00
May Law Flow 3383 2254 0.5333 0.2188 0.3336 0.5898 0.01802 0.01902
June Low Flaw 3018 2254 0.4842 0 0.2531 1 0.00 0.01001
July Low Flaw 2565 2254 0.3906 0 0.1212 1 0.00 0.05806
August Low Flow 2310 3475 0.4301 0.5893 0.5042 0.3702 0.00 0.01702
September Law Flow 2037 2932 0.4064 0.4321 0.4395 0.06329 0.00 0.7217
EFC Parameters
Extreme law peak 1139 0 0.2023 0 1 1 0.00 0.00
Extreme law duration 2 2 1 0 0 1 0.00 0.00
Extreme law timing 250.3 220 0.1537 0.3204 0.1653 1.084 0.006006 0.002002
Extreme low freq. 2 36 3.5 0.4167 17 0.881 0.00 0.1201
High flaw peak 7578 6710 0.3099 0.1168 0.1146 0.6232 0.00 0.06607
High flow duration 4 5 0.375 0.2 0.25 0.4667 0.00 0.2462
High flow timing 165.5 139 0.2951 0.1434 0.1448 0.5139 0.03904 0.001001
High flow frequency 20 24 0.325 0.5208 0.2 0.6026 0.00 0.03303
High flaw rise rate 2273 2976 0.323 0.351 0.3095 0.0865 0.00 0.6957
High flaw fall rate -1323 -1880 -0.3352 -0.3483 0.4207 0.03898 0.00 0.8779
Small Flaad peak 55620 59410 0.2774 0.2777 0.06825 0.00112 0.5966 0.996
Small Flood duration 25.5 40 1.157 0.7938 0.5686 0.3139 0.01502 0.3303
Small Flaad timing 76 75 0.2596 0.306 0.005464 0.1789 0.9259 0.8729
Small Flood freq. D 0 D 0 0.00 0.00
Small Flaad riserate 10160 7225 1.538 2.515 0.2891 0.6358 0.3504 0.07708
Small Flood fallrate -3941 -2303 -1.091 -0.5767 0.4155 0.4712 0.01201 0.1612
Large flood peak 98860 98860 0.169 0.169 0 D 0.8829 0.989
Large flood duration 14 28 1.5 1.786 1 0.1905 0.0991 0.7608
Large flood timing 174 174 0.4563 0.4563 0 D 0.8829 0.987
Large flood freq. D 0 D 0 0.00 0.00
Large flood rise 17550 29130 0.7093 1.318 0.6604 0.8582 0.1852 0.1652
Large flood fall -11230 -3263 -0.6665 -1.402 0.7095 1.103 0.2182 0.1211
Flow level to begin a high flow event is 5758.000
Flow level to end a high flaw event is 3654.000
Flow level to begin an extreme low flow is 1350.000