# Belews Creek Steam Station

2006-2007 IMPINGEMENT STUDY AND
ASSESSMENT OF ADVERSE ENVIRONMENTAL
IMPACT

Final Report, 2009

Duke Energy
P.O. Box 1006 Charlotte, NC 28201-1006iiiii 

## CITATIONS

This technical report was prepared by

ASA Analysis & Communication, Inc. 5 Fairlawn Drive, Suite 205

P.O. Box 57 Washingtonville, NY 10992

Principal Investigators

W. Dey

J. McLaren ASA Analysis & Communication, Inc.

This Technical Report describes research sponsored by EPRI and Duke Energy.

The Technical Report is a corporate document that should be cited in th e literature in the following manner:

Belews Creek Steam Station: 2006-2007 Impi ngement Study and Assessment of Adverse Environmental Impact , EPRI, Palo Alto, CA, 2009.v 

## REPORT SUMMARY

This report has been prepared for Duke Energy’ s Belews Creek Steam Station to support Clean Water Act Section 316(b) requirements. It pr esents the results of sampling conducted during 2006-2007 to document current levels of impingement of fish and other aquatic organisms at the facility’s cooling water intake. Sampling results are interpreted in terms of the status of Belews Lake, from which the cooling water is withdraw n, and its fish community. Impingement losses are interpreted as to whether they constitute adverse impact to the fish community of Belews

Lake.

Background

Belews Creek Steam Station (BCSS) is a 2,240-MW coal-fired steam-elect ric generating station located on Belews Lake in Stokes County, Nort h Carolina approximately 27 km northeast of Winston-Salem, North Carolina. It has tw o generating units, each capable of producing 1,120 MW. The station uses once-through cooling for both of its units. Together, the two units have a design cooling water capacity of 1,454 MGD. Unit 1 began operation in August 1974 and Unit 2 began in December 1975. BCSS operates primarily as a baseload facility. During 2002 through 2007, the average annual capacity factor for BCSS was 74 percent, and th e average total annual flow rate for the cooling water intake wa s 79 percent of the maximum design capacity.

Impingement sampling was conducted biweekly (e very other week) from 25 April 2006 through 11 April 2007. BCSS has eight intake bays, each having a single 3/8-in. (9.5-mm) mesh panel screen fixed screen, with four fixed screens per unit. To sample each screen, a crane operator had to place a back-up screen behind the fixed sc reen, then lift the fixed screen panel over a screen wash trough that led to a co llection basin before proceeding to the next fixed screen to be washed or sampled. In this manner, all screen s associated with operating cooling water pumps were pressure-washed and sampled sequent ially during each sampling event.

Impingement Sampling Results

During 26 sampling events, a total of 706 fish we ighing a total of 4,247 g was collected. Eleven fish species were found in the impingement collecti ons. No state or federa lly-listed threatened or endangered species were impinged. Bluegill an d threadfin shad dominated the collections, comprising 77.2 percent and 16.9 percent of the fi sh collected, respectively. For the 12-month period from 19 April 2006 to 18 April 2007, an estimated 9,638 fish and 57.75 kg of fish biomass were impinged at BCSS. This estimate was derived from the density of fish collected during each sampling event, expressed as numbe r per volume of cooling water withdrawn at each of the two generating units, extrapolated over the full 12-month period.

Impingement rates were highest from late fall through the spring, November to early June, and lowest in summer and early fall, mid-June throu gh October. This season al impingement pattern largely reflected the impingement rates for blue gill because of its dominance in the impingementvi collections. The peak impingement rate for al l species combined occurred on 2-3 January 2007 at 23.0 fish per 1,000 m 3 of water withdrawn. Bluegill acco unted for 96 percent of this peak impingement event. Impingement rates during 2006-2007 did not appear to be influenced by water temperatures, lake levels, or di ssolved oxygen (DO) concentrations.

AEI Assessment Results

The potential for the estimated levels of impinge ment levels at BCSS to be considered “adverse environmental impact” under §316(b) of th e Clean Water Act was assessed. Adverse environmental impact was defined as an unacceptable reduction in:

 biological integrity as meas ured in terms of aquatic community species composition, diversity, and functional organi zation in Belews Lake; or,

 human use of the aquatic resources of Belews Lake, especially fishing opportunity or catch quantity or quality.

The assessment used the US Environmental Prot ection Agency’s well-established Framework for Ecological Risk Assessment. Po tential adverse effects were a ddressed from two perspectives: prospective (predicted future risks) and retrospe ctive (effects linked to pr esent operation). The results were used in a “weight-of-evidence” appro ach to determine the overall risk of adverse environmental impact from operation of the BCS S cooling water intake structure on Belews

Lake.

There was no evidence that impingement at BCS S is causing adverse environmental impact in

Belews Lake. This conclusion is based on a careful evaluation of all relevant lines of evidence including the following:

1. Numbers of fish lost as a re sult of impingement are exceedingly small compare to likely sizes of fish populations in Belews Lake. For all but two species, removal rates amounted to less than one fish every other day. For bluegill, removal rates were equivalent to five adults per day, likely less than or similar to the daily harvest by a single angler.

2. Total number impinged each year for threadfin shad amounted to a biomass removal rate of less than 2 grams per surface acre of Belews Lake per year . This species is a highly prolific spawner with high growth rate and short life span. This high reproductive potential can easily compensate for the rela tively small losses at BCSS with no long term

effects.

3. The fish community since the mid-1980s has been recovering from the historic effects of selenium contamination. Recent data appear to show the continuation of this recovery, despite any impacts potentially resulting from impingement losses at BCSS.

4. Estimates of total fishery catch that could re sult from the fish impinged at BCSS had they survived amount to only 108 lb (49 kg) per year , most of which was bluegill. This level

of harvest is less than what would be expected annually from a few anglers.vii 5. Estimates of the total production foregone as a result of fish impi nged at BCSS amounted to less than 730 lb (331 kg) per ye ar of biomass. Most of this was a result of bluegill, an abundant species in Belews Lake.

6. The best estimate of the total economic value of fish impinged at BCSS was $883 per year. Even considering the uncertainty in th ese estimates, it is highly unlikely that the economic value exceeds $1,700 per year. These values must be considered insignificant compared to the total economic value of the recreational fishery in Belews Lake.

Keywords Clean Water Act §316(b)

Economics Cooling water intake structures

Fisheries Environmental impact assessmentviiiix 

## CONTENTS

INTRODUCTION .................................................................................................................. .......... 1-1

Background .................................................................................................................... ............ 1-1

Report Organization ........................................................................................................... ........ 1-2

PLANT AND SOURCE WATERBOD Y DESCRIPTIONS .............................................................. 2-1

Belews Creek Steam Station..................................................................................................... . 2-1

Cooling Water Intake Structure ............................................................................................. 2- 1

Plant Operation and Water Withdrawal ................................................................................. 2-1

Belews Lake ................................................................................................................... ............ 2-2

Geomorphology and Aquatic Habitat ..................................................................................... 2-2

Water Quality ................................................................................................................. ........ 2-3

FISH COMMUNITY DESCRIPTION ............................................................................................... 3-1

Description of Available Information .......................................................................................... . 3-1

Species Composition............................................................................................................ ...... 3-1

Community Structure............................................................................................................ ...... 3-3

Protected Species ............................................................................................................. ......... 3-3

Target Species ................................................................................................................ ........... 3-4

Bluegill ...................................................................................................................... ............. 3-4

Threadfin shad ....................................................................................................................... 3-5

Largemouth Bass ............................................................................................................... ... 3-5

Channel catfish ............................................................................................................... ....... 3-6

IMPINGEMENT MORTALITY ......................................................................................................... 4-1

Impingement Sampling Methods ................................................................................................ 4 -1

Impingement Sampling Results .................................................................................................. 4-2

Species Composition ........................................................................................................... .. 4-3

Seasonal Patterns and Fish Size .......................................................................................... 4-4

Variables Affecting Impingement Rates ................................................................................ 4-5

Environmental Variables ................................................................................................... 4-5

Species-Specific Abundance and Spatial Distribution ...................................................... 4-6x Annual Losses ................................................................................................................. ........... 4-6

Annual Variability ............................................................................................................ ....... 4-7

Intake Operation .............................................................................................................. . 4-7

Environmental Variables ................................................................................................... 4-7

Fish Abundance ................................................................................................................ 4-8

Comparison of Annual Monitoring Programs .................................................................... 4-8

ASSESSMENT OF ADVERSE ENVI RONMENTAL IMPACT ........................................................ 5-1

Introduction .................................................................................................................. .............. 5-1

Assessment of Ecosystem Effects ............................................................................................. 5 -3

Prospective Approach .......................................................................................................... . 5-3

Retrospective Approach ........................................................................................................ 5-4

Fish Abundance ................................................................................................................ 5-5

Species Richness ............................................................................................................. 5-6

Trophic Structure ............................................................................................................. . 5-6

Retrospective Summary.................................................................................................... 5-6

Effects on Human Uses.......................................................................................................... .... 5-7

Equivalent Loss Measures .................................................................................................... 5 -7

Economic Value ..................................................................................................................... 5-8

Uncertainty in Economic Value .............................................................................................. 5-9

Conclusions ................................................................................................................... ............. 5-10

REFERENCES CITED .............................................................................................................. ...... 6-1

APPENDIX A: METHODS TO ESTIMATE EQUIVALENT LOSS AND ECONOMIC
VALUE OF FISH IMPINGED AT BELEWS CREEK STEAM STATION ........................................ A-1

Introduction .................................................................................................................. .............. A-1

Estimates of Target Species Equivalent Losses ........................................................................ A-1

Assignment of Age Categories for Impinged Individuals ....................................................... A-4

Life Table Information ........................................................................................................ .... A-4

Life Stage Durations .......................................................................................................... .... A-4

Natural Mortality Rates ....................................................................................................... ... A-4

Fishing Mortality Rates ....................................................................................................... ... A-5

Fishing Capture Rates ......................................................................................................... .. A-6

Fishing Vulnerability Rates ................................................................................................... . A-7

Weight at Beginning of Age ................................................................................................... A-7xi Economic Valuation Methods .................................................................................................... . A-8

Direct Use Values ............................................................................................................. ..... A-8

Market Values (Commercial Fishing) .................................................................................... A-8

Non-Market Direct Use Values (Recreational Fishing) .......................................................... A-9

Indirect Use Benefits ......................................................................................................... .... A-10

Non-Use Benefits .............................................................................................................. .... A-12

Adjustment for Other Species ................................................................................................ A-13

Uncertainty Analysis .......................................................................................................... ......... A-13

Inputs to Direct and Indirect Use Benefits ............................................................................. A-15

Sensitivity Analysis .......................................................................................................... ...... A-15

Monte Carlo Analysis ............................................................................................................. A-16xii 

## LIST OF FIGURES

Figure 2-1 Location of the Belews Creek Steam Station .......................................................... 2-4

Figure 2-2 Aerial View of the Belews Creek Steam Station ...................................................... 2-5

Figure 4-1 Seasonal Pattern of Impingement Rates for All Species Combined ........................ 4-9
Figure 4-2 Seasonal Impingement Pattern and Length Frequency of Impinged Bluegill ........ 4-10

Figure 4-3 Seasonal Impingement Pattern and Length Frequency of Impinged Threadfin
Shad .......................................................................................................................... ....... 4-11
Figure 4-4 Seasonal Impingement Pattern and Length Frequency of Impinged Largemouth Bass ............................................................................................................. 4 -12
Figure 4-5 Seasonal Impingement Pattern and Length Frequency of Impinged Channel
Catfish ....................................................................................................................... ....... 4-13
Figure 4-6 Daily Lake Level, Dissolved O xygen Concentration, and Intake Water Temperature vs. Impingement Rate for All Species Combined, April 2006-April

2007 .......................................................................................................................... ....... 4-14
Figure 4-7 Daily Lake Level, Dissolved O xygen Concentration, and Intake Water Temperature vs. Impingement Rate for Young-of-Year (YOY) and Yearling and Older (YAO) Bluegill, April 2006 – April 2007................................................................... 4-15

Figure 4-8 Daily Lake Level, Dissolved O xygen Concentration, and Intake Water Temperature vs. Impingement Rate for Young-of-Year (YOY) and Yearling and Older (YAO) Threadfin Shad, April 2006 – April 2007...................................................... 4-16

Figure 5-1 Total Annual Catch of Fish in Belews Lake, 1996-2005 ........................................ 5-11

Figure 5-2 Mean Annual Catch of Bluegill, Largemouth Bass, Threadfin shad and Channel Catfish in Belews Lake Using Boat Electrofishing Sampling, 1996-2005 .......... 5-12

Figure 5-3 Total Number of Fish Species Found in Annual Electrofishing Surveys of Belews Lake, 1996-2005 .................................................................................................. 5-13

Figure 5-4 Species Composition in Belews Lake, 1996-2005 ................................................ 5-14

Figure 5-5 Percent Composition of Fish Trophic Guilds in Belews Lake, 1996-2005 ............. 5-15

Figure 5-6 Estimates of the Range of Effects of Uncertainty in Each Input Parameter on
Estimates of Annual Economic Benefit at BCSS ............................................................. 5-16

Figure 5-7 Results of Monte Carlo Analysis of Uncertainty in Key Input Parameters on
Estimates of Annual Economic Benefits at BCSS ............................................................ 5-17xiii 

## LIST OF TABLES

Table 2-1 Monthly Mean Cooling Water Flow Rate (MGD) and Percentage of Maximum Flow Rate and Net Capacity Generation at BCSS, 2002-2007 .......................................... 2-6

Table 3-1 Common and Scientific Names of Fish Species Reported from Duke's Electrofishing of Belews Lake during 1994-2005 ............................................................... 3-8

Table 3-2 Number of Fish Caught Annually by Electrofishing at 20 300-m Shoreline Transects in Belews Lake and Percent Composition, 1996-2005 ...................................... 3-9

Table 3-3 Number of Fish Caught Annually by Electrofishing at 10 300-m Shoreline Transects in the Upper and Middle Regions of Belews Lake and Percent Composition, 1996-2005 .................................................................................................. 3-10

Table 3-4 Number of Fish Caught Annually by Electrofishing at 10 300-m Shoreline Transects in the Lower Region of Belews Lake and Percent Composition, 1996-

2005 .......................................................................................................................... ....... 3-11
Table 3-5 Fish Species Occurring within the Dan River System and Listed by the North Carolina Natural Heritage Program as Endangered, Threatened, Of Concern, or

Rare .......................................................................................................................... ....... 3-12
Table 4-1 Impingement Sampling Dates and Time at BCSS during 2006-2007 ...................... 4-17

Table 4-2 Fixed Screens Sampled for Impingement, by Unit and Sampling Date, 2006-

2007 .......................................................................................................................... ....... 4-18
Table 4-3 Estimated Total Number and Biomass of Fish Impinged at BCSS, 19 April 2006 – 18 April 2007 ........................................................................................................ 4 -19

Table 4-4 Total Number and Percent Composition of Fish Collected at BCSS, 25 April 2006 – 11 April 2007 ........................................................................................................ 4 -20

Table 4-5 Total Biomass and Percent Composition of Fish Collected at BCSS, 25 April 2006 – 11 April 2007 ........................................................................................................ 4 -20

Table 4-6 Number and Percent Composition of Taxa Other Than Fish at BCSS, 25 April 2006 – 11 April 2007 ........................................................................................................ 4 -21

Table 4-7 Estimated Total Number and Biomass of Fish Impinged Monthly at both Units of BCSS, 19 April 2006 – 18 April 2007 ........................................................................... 4-22

Table 4-8 Maximum Total Length (mm) Used to Distinguish Young-of-Year from Yearling Fish by Month .................................................................................................... 4-2 5
Table 4-9 Estimated Annual Impingement of Fish by Age Group at both Units of BCSS, 19 April 2006 – 18 April 2007 ........................................................................................... 4-26

Table 4-10 Comparison of Relative Abundance of Fish Species in the 1996-2005 Electrofishing Surveys for all Sampling Transects Combined in Belews Lake and the 2006-2007 BCSS Impingement Collections ............................................................... 4-27

Table 4-11 Estimated Total Number and Biomass of Fish Impinged Monthly at both Units of BCSS for Full Flow Operations, 19 April 2006 – 18 April 2007 ........................... 4-28

Table 5-1 Trophic Guild Assignments for Fish Species in Belews Lake ................................. 5-18xiv Table 5-2 Estimates of Potential Total Annual Equivalent Fishery Yield (lb) from Individuals Impinged for Each Target Species at BCSS .................................................. 5-19

Table 5-3 Estimates of Potential Total Annual Production Foregone (lb) from Individuals Impinged for Each Target Species at BCSS .................................................................... 5-19

Table 5-4 Estimates of Economic Value of Fish Impinged at BCSS ....................................... 5-201-1 

# 1

INTRODUCTION

Background

ASA Analysis & Communication, Inc. has prepared this report fo r Duke Energy’s Belews Creek Steam Station (BCSS) as part of the applica tion process for a National Pollution Discharge Elimination System (NPDES) permit from the No rth Carolina Department of Environment and Natural Resources (NCDENR). Under the Clean Water Act §316(b), an NPDES permit applicant must demonstrate that the location, de sign, construction and capa city of its cooling water intake structure represents Best Tec hnology Available (BTA) for minimizing adverse environmental impact. The primary impacts of concern under §316(b) are entrainment of smaller aquatic organisms into the cooling wate r system or impingement of larger organisms onto traveling screens in the cooling water intake.

In an effort to establish and enforce consis tent national standards under CWA §316(b), the U.S. Environmental Protection Agency (EPA) publishe d a Phase II Rule [69 Fed. Reg. 41576 (9 July 2004)]. The Rule applied to existing electric generating facilities that operate cooling water intake structures (CWIS) with a minimum de sign capacity of 50 million gallons per day (MGD), withdraw water from waters of the U.S., and us e 25 percent or more of the water withdrawn for cooling purposes. BCSS fits this definition for a Phase II facility. Compliance with the Phase II Rule was based on achieving performance standards for reduction of impingement mortality and entrainment set by the EPA on the basis of facilit y location. The Rule required that impingement mortality be reduced by 80 to 95 percent and entrainment be reduced by 60 to 80 percent, compared to a baseline level (i.e., the calcula tion baseline) specifica lly determined for the facility. Adhering to the Phas e II Rule guidelines, BCSS would not be subject to entrainment reduction performance standards because it is loca ted on a reservoir that has a retention time of 1,236 days at mean annual volume (Alden 2004). This retention time exceeds the criterion of seven days set by the Rule as the minimum retenti on time for a reservoir to not be considered as

a riverine environment.

In 2006, the Phase II Rule was challenged in the U. S. Court of Appeals for the Second Circuit, which reached a decision on 25 January 2007. The decision remanded several provisions of the Phase II Rule, including BTA determination, perfor mance standards, cost-cost and cost-benefitIntroduction

1-2 analysis 1 , compliance according to th e Technology Installation a nd Operation Plan (TIOP), restoration as a compliance alternative, and “inde pendent supplier” provisions. In response to this decision, EPA suspended the Phase II Rule [72 Fed. Reg. 37107 (9 July 2007)] and directed that permit requirements for cooling water intake structures at Phase II fa cilities be established on a case-by-case best professiona l judgment (BPJ) basis. Ho wever, the requirement that permitting agencies develop BPJ controls for cooling water intake structures that reflect BTA for minimizing adverse environmental impact (AEI) was retained.

To comply with the regulations, Duke Energy prepared a Proposal for Information Collection (PIC) for BCSS that included the study design for impingement sampling and submitted the PIC to the NCDENR for review. The results of the imp ingement study are the subj ect of this report.

Since the Phase II Rule was remanded after th e PIC preparation and §316(b) is now being administered under BPJ, the analytical approach described in the PIC has been modified to be appropriate for a BPJ approach rather than for co nformance to the remanded Phase II Rule. This report presents the results of sampling conducted at BCSS during 2006-2007 in order to document current levels of impingement at the f acility’s cooling water intake. Sampling results are interpreted in terms of the status of Belews Lake, from which the co oling water is withdrawn, and its fish community.



### Report Organization

Section 2 provides pertinent information on the st ructure and operation of the station’s cooling water intake structure, as well as a brief desc ription of the geomorphology and aquatic habitat of

Belews Lake. Section 3 describes the river’s fish community composition and structure, particularly as related to sus ceptibility to impingement at the BCSS intake. Section 4 presents the results of the 2006-2007 impingement sampling program, describes the seasonality and size distribution of impinged fish, a nd analyzes the possible influen ce of environmental factors and changes in the fish community on impingement rate s. This information is used to characterize current levels of impingement at BCSS. Secti on 5 discusses the observed level of impingement mortality in terms of whether it constitutes adve rse impact on the fish community of Belews Lake, using both a predictive appr oach and a retrospective appro ach. The predictive approach uses modeling to express impingement losses in te rms of equivalent reduc tions in yield to the lake fishery and to estimate the economic value of the losses. The retrospective approach evaluates the composition of the current fish comm unity to determine whether there is evidence of trends that could indicate impairments or instability related to impingement losses.

1 The Supreme Court has reviewed the S econd Circuit Court Decision on the extent to which the cost of compliance

can be considered relative to the benefits. Their decision was issued on 1 April 2009. The Supreme Court upheld

EPA’s use of the Cost-Benefit Test in the Phase II Rule. This provision of the Rule allowed facilities to compare the cost of technologies to meet performance standards to the benefit that would be achieved. Facilities were not required to install technologies that had a cost significantly greater than the benefit.2-1 

# 2

PLANT AND SOURCE WATERBODY DESCRIPTIONS

This section describes the cooling water intake structure of the Belews Creek Steam Station (BCSS), its operation, and its coo ling water source, Belews Lake.



### Belews Creek Steam Station

BCSS is located on Belews Lake in Stokes County, North Carolina approximately 27 km northeast of Winston-Salem, North Carolina (Figure 2-1). It has two coal-fired steam electric generating units, each capable of producing 1,120 MW. The stat ion uses once-through cooling for both of its units. Together, the two units have a design cooling water capacity of 1,454 MGD. Unit 1 began operation in August 1974 and Unit 2 began in December 1975.

Cooling Water Intake Structure

As its cooling water source, BCSS uses Belews Lake, an impoundment of Belews Creek near its

confluence with the Dan River in the northwest ern Piedmont area of North Carolina. The cooling water intake for BCSS is located on the we stern end of a natural cove near mid-lake, and the cooling water is discharged th rough two outfalls to the south of the intake structure (Figure 2- 2). There are eight circulati ng pumps, four per unit. Each pump has a design capacity of 292.4 cfs (131,250 gpm).

The cooling water intake has eight bays, each one devoted to a circulating pump. Each bay contains an 18.5-ft (5.6-m) wide fixed screen having 3/8-in. (9.5- mm) mesh. Upstream from the

fixed screens are trash racks made of steel bars with 2.5-in. (6 .4-cm) clear spacing. An alarm

sounds when the head differential at the fixed sc reens reaches 10 in (25 cm). The screens are cleaned by a high pressure spray when in a raised position. At full pond level and maximum design flow, the flow velocity approaching the fi xed screens is 0.8 fps (2 cm/s). There are no accommodations for returning impinged fish to the lake.

Plant Operation and Water Withdrawal

BCSS operates primarily as a baseload fac ility. During 2002 through 2007, the average annual capacity factor for BCSS, based on Maximum Ne t Dependable Capacity, was 74 percent (Table 2-1). The average total annual intake flow rate for 2002 thro ugh May 2007 was 79 percent of the maximum design capacity, 1,459 MGD (Table 2-1) . Annual flows during this period ranged from 53 percent (2003) to 89 percent (2006) of the maximum design cap acity. Intakes flowsPlant and Source Waterbody Descriptions

2-2 generally are highest during the wa rmer months, May-October, and lower during cooler or colder months, especially November - April.

The water velocity approaching the fixed pane l screens is 1.0 fps (0.3 m/s) at maximum

drawdown lake levels with th e plant operating at plant desi gn flow (Alden 2004). At full pond levels and with the plant opera ting at plant design flow capacit y, the velocity approaching the fixed panel screens is 0.8 ft/sec.



### Belews Lake

Geomorphology and Aquatic Habitat

Belews Lake was formed in 1970 as a cooling water reservoir for BC SS by impounding Belews Creek, East Belews Creek, and We st Belews Creek in Stokes and Rockingham counties. Belews

Lake is located within the Dan River drainage basin. The Dan Ri ver basin is the more southern of two major parts of the Roanoke River drainage basin, the other part being the Roanoke River in Virginia. The Roanoke River runs approxi mately 400 miles (644 km) from the Blue Ridge Mountains in northwestern Virg inia to the Albemarle Sound on the Atlantic coast of North

Carolina. Land use in Roanoke River subbasin 03-02-01, in which Belews Lake is located, consists of 73 percent forested land and 25 percen t cropland and pasture, with the remaining land use being urban or water (NCDWQ 2 001). Belews Lake drains a 119- km 2 watershed (NCDENR 2000).

Belews Lake reached full pond in April 1973 at a su rface elevation of 725 ft (221 m) above mean

sea level. It has a surface ar ea of 1,563 ha at mean water level, a mean depth of 14.9 m, a maximum depth of 44 m, and 141 km of shorel ine (NCDENR 2000). Wate r surface elevation

varies a maximum of 1.5 m. The lake stratifie s during warm months and experiences a complete

winter turnover.

The lake is stratified from February or March until September, or sometimes as late as

December. When the lake is stratified, maximum temperatures (e.g., in August) can reach 30-

32 o C, while bottom temperatures are 10-13 o C. Winter water temp eratures range from 8 o C to 16

o C. Dissolved oxygen (DO) concentrations in the epilimnion exceed the water quality standard (5 mg/L) year-round, but DO depletion in the hy polimnion (e.g., 0-5 mg/l levels) varies annually (Duke 2001).

In 1985 an air injection system was installed in th e lake at a depth of 17 m to provide cool water to the BCSS intake by means of an upwelling of hypolimnetic water (Duke 2001). The effect of the system has been to deepen the late summer thermocline by 7 to 8 m. This phenomenon has been reported for other stratified lakes in th e southeastern U.S. During recent summers, operation of the air injection system has been redu ced to allow a greater re serve of cool water for a more extended period (Coughlan et al. 2006). In mid-summer, sometimes there is a metalimnetic DO depression that may be caused by settling of oxygen-reducing material at the density gradient at that depth.2-3 Water Quality

Belews Lake is oligotrophic as indicated by consistently low c oncentrations of nutrients and chlorophyll a, especially in the lower portion of the lake downstream from the Route 65 causeway (Duke 2001, NCDWQ 2001, Hining 2003, NC DENR 2006a). It has the lowest productivity of the Roanoke River basin la kes in North Carolina (NCDENR 2000). Water quality analysis has shown differences between uplake and downlake lo cations (upstream and downstream from the NC65 causeway), indicating higher productivity uplake, as well as higher turbidity, and iron, aluminum, total organic carbo n and total suspended solid concentrations.

Belews Lake is classified as B/C, signifying best uses fo r primary recreation, secondary recreation, and aquatic life propagation. Its WS-I V classification provides the fourth lowest level of watershed protection. In its 2001 and 2006 Water Qualit y Plans, the NCDENR Division of Water Quality states that Be lews Lake is oligotrophic and ha s no indications of water quality problems (NCDENR 2001, 2006a).

In the past, water quality in Belews Lake has been an issue due to the discharge of ash residue

effluent into the lake from BCSS from 1976 un til 1985. In 1978 it was determined that this effluent was causing a bioaccumulation of selenium in fish tissues, resulting in severe tissue pathology and reproductive impairment of the fish community (Lemly 1993, 2002; Duke 2001). In 1984, dry fly-ash collection was used to elimin ate input of most selenium and other trace elements, and in 1985 the ash basin discharge was rerouted from the lake to the Dan River.

Recently, water quality has been sampled se mi-annually and sediment has been sampled annually, as required by the sta tion’s NPDES permit. Prior to 2001, the sampling frequency was quarterly for water quality and semiannually for sediment quality. Recent sampling has shown

that concentrations of selenium and arsenic in the water column have d eclined to non-detectable levels (Duke 2001, Coughlan et al. 2006). The termination of ash basin effluent discharge to Belews Lake also has resulted in decreasing leve ls of alkalinity, calcium, sulfates and specific conductance, especially near the former discha rge area. In sediment samples taken during 1996- 2000, concentrations of selenium and arsenic have been reduced in the lake overall and have become less variable spatially, with some reloca tion to deeper areas in the lake. Arsenic and

selenium concentrations in sediments are still elevated relative to non-im pacted sites. Tissue analysis for selenium has been conducted on sel ected fish species, such as common carp, redear sunfish, white crappie, and black crappie. Sele nium concentrations in fish from 2001 through 2005 were less than the 5.0 μg/g standard and di d not exceed 4.3 μg/g (Coughlan et al. 2006). In August 2000, NCDENR removed Belews Lake from a fish consumption advisory and its §303(d) list of impaired waters (NCDENR 2006a).2-4 Figure 2-1 Location of the Belews Creek Steam Station2-5Figure 2-2 Aerial View of the Belews Creek Steam StationPlant and Source Waterbody Descriptions2-6Table 2-1 Monthly Mean Cooling Water Flow Rate (MGD) and Percentage of Maximum Flow Rate and Net Capacity Generation at BCSS,2002-2007Capacity FactorsYear Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual2002 89% 85% 95% 67% 71% 84% 93% 86% 91% 77% 94% 94% 86%2003 39% 49% 31% 19% 44% 51% 51% 87% 83% 49% 50% 51% 50%2004 70% 94% 98% 67% 55% 49% 90% 64% 59% 88% 82% 87% 75%2005 80% 91% 55% 50% 61% 88% 87% 96% 95% 78% 80% 72% 78%2006 87% 68% 63% 53% 95% 84% 74% 93% 88% 77% 71% 80% 78%2007 86% 90% 77% 64% 93% 83% 88% 92% 80% 64% 48% 41% 76%Average75% 80% 70% 53% 70% 73% 81% 87% 83% 72% 71% 71% 74%Actual Plant Flow Rate (MGD)Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual2002 1,294 1,277 1,277 9821,323 1,431 1,424 1,418 1,409 1,119 1,245 1,275 1,2892003 518 636 475 309 638 881 1,131 1,451 1,371 692 582 639 7772004 639 398 1,002 977 997 777 1,3741,114 1,045 1,4291,300 1,163 1,0182005 941 1,006 906 770 1,296 1,458 1,4551,459 1,459 1,4421,333 1,240 1,2302006 1,277 1,231 1,136 9921,432 1,375 1,459 1,459 1,455 1,326 1,112 1,330 1,2992007 1,303 1,335 1,169 1,191 1,334 1,266Percentage of Maximum FlowRate (2,339 CFS or 1,459 MGD)Year Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual2002 89% 88% 88% 67% 91% 98% 98% 97% 97% 77% 85% 87% 88%2003 35% 44% 33% 21% 44% 60% 78% 99% 94% 47% 40% 44% 53%2004 44% 27% 69% 67% 68% 53% 94% 76% 72% 98% 89% 80% 70%2005 65% 69% 62% 53% 89% 100% 100% 100% 100% 99% 91% 85% 84%2006 88% 84% 78% 68% 98% 94% 100% 100% 100% 91% 76% 91% 89%2007 89% 92% 80% 82% 91% N/AN/A N/A N/A N/A N/A N/A 87%Average68% 67% 68% 60% 80% 81% 94% 95% 92% 82% 76% 77% 79%3-1 

# 3

FISH COMMUNITY DESCRIPTION

This section describes the fish community in Be lews Lake. The sources and types of available historical and recent information on the fish community are described first. The species composition and structure of the fish community then are discussed. Finally, the general life history of fish species commonl y found in impingement sampling at Belews Creek Steam Station (BCSS) are discussed as background informati on that might provide insights on annual or seasonal susceptibility to impingement.



### Description of Available Information

The North Carolina Wildlife Resources Co mmission (NCWRC) and Duke Energy have monitored the fish community of Belews La ke since 1972 (Duke 2001, C oughlan et al. 2006). From 1972 through 1994 the monitoring consisted of rotenone sampling of selected coves in the lake. In 1994 a spring electrofishing survey wa s added to the rotenone survey, and after 1994 the spring electrofishing surveys repl aced the rotenone surveys. The electrofishing surveys are designed with the objective of management of th e developing sport fisher y in the lake and to monitor the recovery of the fi sh community after its decline from the effects of selenium contamination in the 1970‘s caused by divers ion of ash basin discharge to the lake.

The spring electrofishing surveys are conducted annually using a boat-m ounted electrofisher during daylight when water te mperatures were between 15 o C and 20 o C. Twenty 300-m shoreline transects (five up-lake, five mid-lake, and 10 dow n-lake) were selected to represent existing habitat types. All collected fi sh are identified to taxon, counte d, and weighed in aggregate. Total numbers and biomass are reported as the su m of the transect results in the uplake and downlake regions. Most importantly, the el ectrofishing data from 1996 to 2005 provide information on the species composition, diversity and relative abundance within the current fish community.



### Species Composition

Duke’s spring electrofishing program during 1994-2005 has identified 27 distinct fish species (plus sunfish hybrid) and eight families in Bele ws Lake (Coughlan et al . 2006 and Table 3-1). Sportfish species include largemouth bass, white crap pie, black crappie, blue gill, channel catfish, yellow perch, and flathead catfish. The dominant fish species are bluegill and threadfin shad, representing 46 percent and 18 percent of the total electrofishing catch from 1996 through 2005 (Table 3-2).Fish Community Description

3-2 There is considerable spatial heterogeneity in the fish communit y, as indicated by the electrofishing catch. For example, 25 fish speci es were caught in the middle and upper portions of the lake over the 10-year ( 1996-2005) period, compared to 17 species in the lower portion of the lake (Tables 3-3 and 3-4). Species notably ab sent from the lower regions of the lake included all catostomids (white sucker, golden redhorse, and notchlip redhorse ), several of the ictalurids (white catfish, snail bullhead, and brown bullhead), and white pe rch. Other species that are

much reduced in abundance in the lower lake include shad (gizzard and threadfin), common carp, shiners (satinfin and golden) , crappie (white and black), a nd yellow perch. In contrast, centrarchids (largemouth bass and sunfish) are nearly equally abundant in the lower and upper portions of the lake.

The differences in the number of species uplake and downlake appear to be related to water quality and productivity differences between th e two areas. Fish biomass in the uppermost portion of the lake (five uplake transects) consis tently has exceeded other lake regions and has averaged 164.6 kg/1,500 m from 1994 to 2005 (Coughl an et al. 2006). At the five midlake sampling transects, the electrofishing catch biomass has averaged 72.9 kg/1,500 m. Downlake, the biomass has averaged 16.6-25.4 kg/1,500 m since 1994. At uplake locations, there is higher turbidity and concentrations of iron, aluminum, total organic car bon, and total suspended solids. Whereas the lower portions of the lake are char acterized as being oli gotrophic, and middle and upper portions may be more mesotrophic. Also, se lenium contamination has been progressively less at sampling locations further uplake (B arwick and Harrell 1997, Coughlan et al. 2006).

Since Belews Lake was created in 1970, the fish community has undergone a transformation

from its initial establishment as a lentic comm unity, through its “collapse” in the late 1970s and early 1980s caused by fly and bottom ash pond ove rflow and selenium contamination, and during its subsequent recovery from the late 1980s to the present. Cove rotenone surveys in the lake provide data on this transformation fr om 1972 through 1994 (Bar wick and Harrell 1997), and electrofishing surveys continue the data base from 1994 to present (Duke 2001, Coughlan et al. 2006).

Prior to 1975-1976, the community was relativel y diverse and dominate d by bluegill, common carp, largemouth bass, and several other sunfish species (Barwick and Ha rrell 1997). Seleniumcontaminated water began to be discharged into the lake in the fall of 1975 and continued until its containment and diversion was completed in 1985. During 1976- 1981, several fish species progressively disappeared from the annual survey catches, leaving only seven of over two dozen species that were formerly there (Barwick a nd Harrell 1997). The total standing crop in the sampled lake coves was reduced from 86.7-115.4 kg/ha in 1972-1975 to only 5.7-15.0 kg/ha in 1980-1981. At its lowest point, the fish comm unity was dominated by fathead minnow and eastern mosquitofish, the latter species known to be tolerant of elevated levels of selenium (Lemly 2002). Other species were rendered e ffectively sterile due to teratogenesis and reproductive impairment caused by selenium cont amination of tissues (Lemly 1993, 2002).

Several species began to reappe ar or increase in abundance in 1984 (Barwick and Harrell 1997). Although present in 1976-1981, common carp and green sunfish began to dominate the catch in 1984, and fathead minnow and eastern mosquitofish declined in abundance. After 1986, a stocking program was instituted to re-establish sport fish in the fish community, such as3-3 largemouth bass and bluegill. By 1990-1991, the dominance of common car p and green sunfish had evaporated, and species such as bluegill, largemouth bass, ch annel catfish, and gizzard shad became the dominant species.



### Community Structure

The current fish community structure can be desc ribed in several ways. It is useful to group species according to their resource requirements, such as functional guilds (e.g., feeding or reproductive guilds) and struct ural guilds (e.g., habitat guild s). Feeding guilds provide information on probable trophic dynamics in the community, and are especially helpful for making management decisions if food is a limiting resource (Austen et al. 1994).

Species caught since 1994 may best represent the current fish co mmunity structure in the lake, and can be assigned to primary trophi c guilds (NCDENR 2006b) as follows:

 Piscivores—largemouth bass, bl ack crappie, white crappie, white perch, yellow perch, and

flathead catfish

 Insectivores—bluegill, green s unfish, redbreast sunfish, rede ar sunfish, hybrid sunfish, pumpkinseed, warmouth, satinfin shiner, golde n redhorse, notchlip redhorse, white catfish, snail bullhead, flat bullhead, and eastern mosquitofish

 Omnivores—gizzard shad, threadfin shad, golde n shiner, fathead minnow, white sucker, white catfish, brown bullhead, ch annel catfish, and common carp

Piscivores feed primarily on other fish as adults . Insectivores feed pr imarily on insects, and omnivores feed on anything availabl e, including invertebrates, eggs , plant material, and detritus. There is a diversity of species within each tr ophic guild in Belews Lake. Gizzard shad and threadfin shad, along with the young of other specie s, particularly sunfish, provide the food base for the lake’s piscivorous predators, su ch as largemouth bass and crappie.



### Protected Species

There are 10 fish species listed by the North Caro lina Natural Heritage Program (LeGrande et al. 2008) that have been reported to occur in the Da n River drainage system (Table 3-5). Three are classified as endangered, one as threatened, three as species of special concern, and three as significantly rare. None has been caught in Belews Lake during Duke’s electrofishing surveys or has been impinged at BCSS.

The bigeye jumprock is a threatened species that is restricted primarily to the part of the Dan River running through Upper Precam brian-Paleozoic rocks, where it is associated with boulder substrate and undercut banks (Rohde et al. 1994, R ohde et al. 2003). The ri verweed darter is a species of special concern that is endemic to the upper and middle Roanoke River drainage basin, but the only extension of its range into North Carolina occurs in the Dan River. It prefers rock riffle areas (Rohde et al. 1994). The Ro anoke bass, Roanoke hog sucker, and quillback are not protected species, but are considered to be significantly rare by the NCNHP, which has determined that they need to be monitore d due to their limited abundance in the state.Fish Community Description

3-4 The remaining five species are the cutlip minnow Exoglossum maxillingua (state species of special concern), orangefin madtom Notorus gilberti (state endangered and federal species of concern), Roanoke logperch Percina rex (state and federal enda ngered), rustyside sucker

Thoburnia hamiltoni (state endangered and federal species of concern), and Blue Ridge sculpin

Cottus caeruleonmentum . All but the Roanoke logperch have been found in the Dan River in the Mountain, Gorge, or Piedmont regions (Rohde et al. 2001, 2003). The Roanoke logperch in the Roanoke River system is limited to the upper Ro anoke, Pigg, and Smith rivers of Virginia (Rosenberger and Angermeier 2002), and thus possi bly the Dan River drainage (Smith River) in Rockingham County (LeGrande et al. 2008).



### Target Species

Among all fish species found in Belews Lake, a subset of species was selected for a detailed evaluation of impingement mortality presently occurring at the BCSS cooling water intake. These species either are most frequently observe d in impingement collections, or are important because of their economic value or value to the ecosystem.

The most abundant species in impingement collecti ons at BCSS is the bluegill (Section 4). The bluegill is both an important prey species for larg er predators and an impo rtant panfish species in the recreational fishery. As a target species, it also can act as a surrogate for other impinged sunfish species such as green sunfish, warm outh, redbreast sunfish, pu mpkinseed, and redear sunfish. The second-most frequently impinged species is the threadfin shad. It is an important forage species in Belews Lake and prey for game species including largemouth bass, channel catfish, white crappie, black crappie, and white pe rch. The last two species selected as target species are the largemouth bass and channel catfish. Both support important recreational fisheries in the lake and are among the six most frequently impinged species.

This section presents background information on the life history of these five species.

Bluegill

Bluegill is the most abundant species in Belews Lake, comprising 48.7 percent of all fish caught during Duke electrofishing survey s of 1996-2005 (Table 3-2). It al so was the species found most frequently in the 2006-2007 impingement coll ections, comprising 77.2 percent of the fish collected (Section 4).

The bluegill is native to much of the eastern and central U.S. and occurs in warm, slow or still water, usually associated with aquatic vegetati on and woody debris (Rohde et al. 1994). It has been stocked widely in the mid-Atlantic region and, in fact, was restocked into Belews Lake following the collapse of the fish community caused by selenium contamination (discussed above) to help restore the sport fishery of the lake. Previously, bluegill also had been the dominant species in the lake (Barwick and Harrell 1997). Individual movements tend to be highly localized. Their diet consists mostly of invertebrates, but larger bluegills may become piscivorous.3-5 In the Middle Atlantic region, bluegill spawn during May and June when water temperatures

reach 70 o F (21 o C) (Rohde et al. 1994). The spawning season can be protracted over several months. Bluegill are col onial breeders in the sense that spawni ng fish build nests that are usually in close proximity to each other. Males constr uct nests that are about 0.3 m in diameter in shallow water (depths of 0.3-0.9 m). The eggs from several females can be fertilized and deposited in the nest, which is then defended by the male until the eggs have hatched. Because the nests are located in shallow depths, water le vel fluctuations can severely impact successful reproduction. Nests and young can be stranded by a lowering water level or disrupted by severe wave action (Heman et al. 1969), or surviv al of the young may be reduced by increased ultraviolet light radiation in highly tr ansparent water (Ols on et al. 2008).

Bluegill in the southeastern U.S. commonly be gin to mature by at age 1 or 75-125 mm for both sexes (Spotte 2007) and can live up to 11 years. Most adults do not exceed 0.5-0.75 lb (227-340 g) (Rohde et al 1994).

Threadfin shad

Threadfin shad is an excellent forage species because of its size, which seldom will exceed 150 mm, and its great productivity. Although present in Belews Lake as early as 1974, it did not become a major component of the fish comm unity until the late 1980s (Barwick and Harrell 1997). Threadfin shad is now the second-most a bundant fish species, representing 13.2 percent of the electrofishing catch dur ing 1996-2005 (Table 3-2).

The threadfin shad is a planktivore, relying on filter feeding through its gill rakers. As planktivores, the young and adults ar e food competitors for other forage species, such as bluegill and the young of several other spec ies. For habitat, threadfin shad prefer open water over sand, mud or debris. They tend to school at shallow depths during the day and widely distribute near the surface at night. It is primarily a warm water species, surviving best when winter temperatures exceed 10 o C (Ruelle et al. 1977).

Threadfin shad spawn when water temperatures reach 65-70 o F (18.3-21.1 o C) and can have multiple spawning peaks through the spring, summe r and early fall (Pflieger 1997, Smith 2002). Spawning primarily occurs from dawn to shortl y after sunrise as spawning schools gather along the shoreline. Their adhesive eggs are broad cast over submerged objects and hatch within three days. Young threadfin shad grow very rapidl y (up to 25 mm. per month), with many reaching maturity and spawning by the end of their firs t summer at approximately 65 mm in length. Females generally grow larger and live longer than males, with a maximum age of about four years for females and three years for males.

Largemouth Bass

Largemouth bass is one of the most sought after sport fishes in the state. Originally, its

distribution within the mid-Atla ntic region was limited to South Carolina (Rohde et al. 1994). Through stocking it is now found throughout the region, where it can reach sizes in excess of 4.5Fish Community Description

3-6 kg (10 lb) and can live up to 13 years. It is one of the most abundant pred ator species in Belews Lake and comprised 4.6 percent of the elec trofishing catch during 1996-2005 (Table 3-2).

Largemouth bass spawn when wate r temperatures reach 15.6-23.9 o C (60-75°F) (Heidinger 1975). In Belews Lake, water temperatures of 60-75°F would occur during April to mid-May, based on temperatures recorded during impi ngement sampling at BCSS during 2006-2007. The male builds a nest in substrate that typically is rocky, sand or gravel and cl eared of organic debris and silt (Emig 1966, Rohde et al. 1994, Pflieger 1997) . The nests are 0.6-1 m in diameter and usually widely spaced (e.g., 9.1 m apart) unless th e available nesting area is limited. Nests are

built in areas of no current or wave action (Pflieger 1997) at depths of 0.3 to 4.6 m.

Males remain at the nest to fan the eggs to k eep them silt-free and to protect the young for up to two weeks (Pflieger 1997). Eggs hatch in 2-5 days (Emig 1966) and the fry form tight schools over the nest and begin to feed in 5-8 days. The schools break up approximately one month after hatching when the young bass are approximately 25 mm long. Growth rates are variable and depend on the lake productivity and food availab ility. Largemouth bass typically mature at about ages 1 to 2 in the region (Carlander 1977, Rohde et al. 1994), or about 250 mm long (Pitlo et al. 2004a).

Channel catfish

The channel catfish is a very important and hi ghly desirable commercia l and recreational fish species throughout its geographic di stribution and in North Caroli na. The channel catfish is native to the central part of No rth America (Smith 1985), but it ha s been stocked in rivers and reservoirs throughout the southeast region. Its inclusion as a target species is based primarily on its importance as a recreational species. Except for the brief period of 1980-1984 (Barwick and Harrell 1997), it has been a resident of Belews La ke at relatively consiste nt levels, numerically averaging 0.6 percent of the electrofishing catch dur ing 1996-2005 (Table 3-2).

Channel catfish spawn in late spring and early summer when water temperatures reach 65°F (18.3°C) or more (McMahon and Terrell 1982, Pitlo et al. 2004b). Spawning generally occurs over a range from 21°C (69.8°F) to 29 ° C (84.2°F), with an optimal temperature of 27°C (80.6°F) (Hubert 1999). Several weeks pr ior to spawning, male s select and clear suitable nest sites, usually consisting of secluded, dark areas such as hollow logs, drift piles, undercut banks, muskrat or beaver burrows, or rip rap. A singl e male often will spawn with several females (Rohde et al. 1994). Eggs are deposited in a gelati nous mass. Incubation lasts for 5.5 to 10 days at 75-82°F (23.9-27.8°C) (Holland-Bartels and Duva l 1988). The male tends the nest while eggs hatch and stays there for about one week after hatchi ng to guard the fry. Early growth is variable among year classes and apparently is dependent upon existing conditions (Pitlo et al. 2004b).

Adults may be found in many habitats including cha nnels and large open area s, but prefer habitat with woody debris, bank cavities and moderate curre nts (Koel et al. 1998). In daylight they seek depths with cover and current. At night or in rising water levels they feed near or on the bottom in shallower depths. Young feed largely on aquatic insects and other bent hic arthropods, but at 100 mm length become omnivorous with fish making up a large part of their diet (Smith 1985).3-7 Maturity begins at age 4 and approximately 305 mm in length (Rohde et al. 1994, Pitlo et al. 2004b). The average fecundity is 6,088 eggs per lb of body weight.3-8Table 3-1 Common and Scientific Names of Fish Species Reported from Duke's Electrofishing of Belews Lake during 1994-2005Family Scientific Name Common NameClupeidae-HerringDorosoma cepedianumGizzard shadDorosoma petenenseThreadfin shadCyprinidae- Minnows and CarpCyprinella analostanaSatinfin shinerCyprinus carpioCommon carpNotemigonus crysoleucasGolden shinerPimephales notatusFathead minnowCatostomidae-SuckersCatostomus commersoniWhite suckerMoxostoma erythrurumGolden redhorseMoxostoma pappillosumNotchlip redhorseIctaluridae-Bullhead catfishesAmeiurus brunneusSnail bullheadAmeiurus catusWhite catfishAmeirus nebulosusBrown bullheadAmeiurus platycephalusFlat bullheadIctalurus punctatusChannel catfishPylodictis olivarisFlathead catfishPoecilidae-LivebearersGambusia holbrookiEastern mosquitofishPercicthyidae-Temperate bassesMorone americanaWhite perchCentrarchidae-SunfishesLepomis auritusRedbreast sunfishLepomis cyanellusGreen sunfishLepomis gibbosusPumpkinseedLepomis gulosusWarmouthLepomis macrochirusBluegillLepomis microlophusRedear sunfishLepomis sp.Hybrid sunfishMicropterus salmoidesLargemouth bassPomoxis annularisWhite crappiePomoxis nigromaculatusBlack crappiePercidae-PerchesPerca flascensYellow perch3-9Table 3-2 Number of Fish Caught Annually by Electrofishing at 20 300-m Shoreline Transects in Belews Lake and PercentComposition, 1996-2005Species 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Total %Gizzard shad 244550142430113592153400.984Threadfin shad 391314133044012021,0001961,86334,55213.179Satinfin shiner 1841873109211434813435171.497Common carp 105122653029623042601106551.896Golden shiner 381-32312183530.153Fathead minnow ----2-----20.006White sucker -11-1-112-70.020Golden redhorse 1---------10.003Notchlip redhorse 2----1----30.009Snail bullhead 1---------10.003White catfish ----112515150.043Brown bullhead -------4--40.012Flat bullhead 3341--4---150.043Channel catfish 251836721673434342130.617Flathead catfish --------1230.009Eastern mosquitofish -------1--10.003White perch 6431713330172351572081029032.614Redbreast sunfish 3034185654863513663883063082563,74710.848Green sunfish 27392011226262450542790.808Pumpkinseed 13-1----1--150.043Warmouth 9675415151220321250.362Bluegill 8588369971,4371,1322,1042,2041,5992,5533,11116,83148.729Redear sunfish 156751051941751951351831502081,5764.563Hybrid sunfish 152838577260732771895301.534Largemouth bass 1671311741611421721331172261711,5944.615White crappie 193364842391163048201828352.417Black crappie 271925423539-1653232790.808Yellow perch 3431121066792881331502231301,4444.181Total 2,3962,1002,7352,9642,6663,6684,3733,0186,1474,47334,540100.000Fish Community Description3-10Table 3-3 Number of Fish Caught Annually by Electrofishing at10 300-m Shoreline Transects in the Upper and Middle Regions ofBelews Lake and Percent Composition, 1996-2005Species 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Total %Gizzard shad 244449122430113488153311.333Threadfin shad 391314133044011371,0001961,86334,48718.077Satinfin shiner 18976868191204313153801.531Common carp 9596592629622939581106032.429Golden shiner 381-2228183470.189Fathead minnow ----2-----20.008White sucker -11-1-112-70.028Golden redhorse 1---------10.004Notchlip redhorse 2----1----30.012Snail bullhead 1---------10.004White catfish ----112515150.060Brown bullhead -------4--40.016Flat bullhead 3211--3---100.040Channel catfish 221031511343021331700.685Flathead catfish -----------0.000Eastern mosquitofish -----------0.000White perch 6431713330172351572081029033.638Redbreast sunfish 20129229525617089603887821,5706.325Green sunfish 27391511224122448482501.007Pumpkinseed 13-1----1--150.060Warmouth 751532271213570.230Bluegill 5486716961,0348021,0011,5428191,9992,24911,36145.770Redear sunfish 9938521541288563109971749994.025Hybrid sunfish 112221242793225151590.641Largemouth bass 97759692777685621401069063.650White crappie 193364842391163048201828353.364Black crappie 261925423539-1646232711.092Yellow perch 3431121066792881331502141301,4355.781Total 1,8371,6411,9892,1761,9541,9463,1371,7935,1413,20824,822100.0003-11Table 3-4 Number of Fish Caught Annually by Electrofishing at 10 300-m Shoreline Transects in the Lower Region of Belews LakeandPercent Composition, 1996-2005Species 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 Total %Gizzard shad -112---14-90.093Threadfin shad -----65----650.669Satinfin shiner -3215412235-281371.410Common carp 102664--132-520.535Golden shiner ----1-14--60.062Fathead minnow -----------0.000White sucker -----------0.000Golden redhorse -----------0.000Notchlip redhorse -----------0.000Snail bullhead -----------0.000White catfish -----------0.000Brown bullhead -----------0.000Flat bullhead -13---1---50.051Channel catfish 38521334131430.442Flathead catfish --------1230.031Eastern mosquitofish -------1--10.010White perch -----------0.000Redbreast sunfish 1021262702301812773282682211742,17722.402Green sunfish --5--214-26290.298Pumpkinseed -----------0.000Warmouth 216-113135819680.700Bluegill 3101653014033301,1036627805548625,47056.287Redear sunfish 5737534047110727453345775.937Hybrid sunfish 4617334551702546743713.818Largemouth bass 705678696596485586656887.080White crappie -----------0.000Black crappie 1-------7-80.082Yellow perch --------9-90.093Total 5594597467887121,7221,2361,2251,0061,2659,718100.000Fish Community Description

3-12 Table 3-5 Fish Species Occurring within the Dan River System and Listed by the North Carolina Natural Heritage Program as Endangered, Threatened, Of Concern, or Rare

Species Status* Rank**

Blue Ridge sculpin SC S1

Bigeye jumprock T S1

Cutlip minnow SC S1

Orangefin madtom E S1

Quillback SR S1

Riverweed darter SC S3

Roanoke bass SR S2

Roanoke hog sucker SR S3

Roanoke logperch E S1

Rustyside sucker E S1

*E= endangered, T = threatened, SC = spec ial concern, SR = significantly rare

**S1 = critically imperiled in North Carolina due to extreme rari ty or some factor(s) making it especially vulnerable to extirpation (local extinction)

S2 = imperiled in North Carolina due to rarity or some factor(s) making it very vulnerable to extirpation

S3 = vulnerable to ex tinction in North Carolina either because rare or uncommon, or found only in a restricted range (even if abundant in some locations), or due to other factors making it vulnerable to extirpation4-1 

# 4

IMPINGEMENT MORTALITY

This section presents the methods and resu lts of an impingement monitoring program conducted at BCSS during 2006-2007. The obs erved effects of seasonality and environmental variables, including lake leve l, dissolved oxygen (DO) concentration and water temperature, on impingement rates are di scussed for dominant fish species in the 2006-2007 collections. The potential for inter-an nual variability in impingement losses at

BCSS also is discussed.



### Impingement Sampling Methods

Current impingement at BCSS was evaluate d by a monitoring program conducted during 2006-2007 by MACTEC Engineering and Cons ulting, Inc. Complying with the requirements of the §316(b) Phase II Rule, Duke Energy submitted a Proposal for Information Collection (PIC) to North Carolin a Department of Environment and Natural Resources (NCDENR) outlining a proposed pl an for impingement data collection and analysis, and associated Quality Assuranc e/Quality Control (QA/QC) procedures.

BCSS has eight intake bays, each of which has a fixed 3/8-in. (9.5-mm) mesh panel screen (Section 2). To sample impingement on each screen, a crane operator had to place a back-up screen behind the fixed screen to be sampled, then lift the fixed screen panel over a screen wash trough that led to a coll ection basin. A 1/4-in. (6.4-mm) mesh net was

inserted into the collection basin to recover the impinged fish sample from each washed fixed screen. The screen panels then we re pressure-washed, af ter which the back-up screen was placed behind the next screen to be sampled. In this manner, all screens associated with operating cooling water pum ps were washed and sampled sequentially during each sampling event. Units that ope rated on each sampling date and associated screens sampled are shown in Table 4-1.

Sampling during the 2006-2007 impingement monitoring program was conducted biweekly (every other week) starting on 25 April 2006 and continui ng until 11 April 2007 (Table 4-2). Prior to sampling, the fixed pa nel screens were raised and cleaned, then replaced and allowed to accumulate impinged fish for approximately 24 h. On the second day (after the 24-h accumulation), impinged fish were washed from the raised screens and collected. The back-up screen be hind the cleaned screen also was examined for any impinged fish that might have wash ed off the screen that had been lifted. 2

2 Only partially decomposed fish were observed, indicating they had been previously dead.Impingement Mortality

4-2 Impinged specimens recovered from the co llection basin net were processed in accordance with Standard Operating Procedur es (SOP) prepared specifically for this facility prior to the start of data collection. Individual fi sh counts by species and length and weight measuremen ts were recorded.



### Impingement Sampling Results

For the 12-month period from 19 April 2006 to 18 April 2007, an estimated 9,638 fish and 57.75 kg of fish biomass were impinged at BCSS (Table 4-3), based on the collection of 706 impinged fish (Table 4-4) and 4,247 g of fish biomass (Table 4-5). This estimate was derived from the density of fish collect ed during each sampling event, expressed as number per volume of cooli ng water withdrawn at each of the two generating units, extrapolated over the full 12-month period. To estimate the density at each unit for each sampling event, the collection totals for a ll screens at that unit were combined and divided by the total flow volume for the unit during the 24-h sampling period. Total daily cooling water intake fl ow volumes for sampling days were obtained from plant operation records.

Impingement density values for non-sample d days were estimated by interpolating between density values for the sampling da ys that were immediately previous and subsequent to the unsampled time interval, then multiplying the interpolated density by each total daily intake flow reported for the non-sampled days and summing the estimated impingement counts across the time interval:

) )( 2 / ( 2

1 2 1

1 

##  

    

i uj s s n

j i s si p F D D F D N

Where

N

p = estimated total impingement during non-sampled period p and the sampled days bordering the period

D si = organism density of sampling day i (1 = start, 2 = end) of period p

F

si = 24-hour cooling water flow volume on sampling day i in period p

F

uj = 24-hour cooling water flow volum e on non-sampling day j in period p

n = number of non-sampled days during period p

Total annual impingement then was estimat ed by summing the estimated impingement during sampled days and non-sampled periods for each unit, then summing across the

two units.4-3 Species Composition

A total of 11 distinct fish species were found in the impinge ment collections (Tables 4-4 and 4-5). In addition, fish identified only to family Clupeidae (herring/shad), Centrarchidae (sunfish), and Cyprinidae (minnows/shiners/carp) or to genus Lepomis were collected; identification of these fish to species was not possible due to the capture of incomplete specimens or physical damage.

Bluegill and threadfin shad dominated th e collections, comprising 77.2 percent and 16.9 percent of the fish collected, respectively (Table 4-4). Togeth er these two species accounted for 94.0 percent of the estimated total annual impingement in terms of numbers (Table 4-3) and 76.5 pe rcent of the estimated tota l impinged biomass. When included with largemouth bass and channel ca tfish, these four target fish species (described in Section 3) accounted for 95.7 percent of the estimated numbers impinged and 82.0 percent of the fish biomass impinged during the 12-month period.

Centrarchids were by far the most dominant fish, accounting for 80.9 percent of the estimated total annual impingement, followe d by clupeids with 18.1 percent. Besides bluegill, the centrarch id species included green sunfish, hybrid sunfish, redbreast sunfish, redear sunfish, largemouth bass, and spotted bass (Table 4-3). Besides threadfin shad, the clupeid species included gizzard shad a nd alewife. The remaining 1 percent of the estimated total annual impingement cons isted of channel catfish (0.7 percent), unidentified cyprinind speci es (0.1 percent), and wh ite perch (0.1 percent).

Two species identified in impingement coll ections—alewife and spotted bass—have not been found by electrofishing in Belews Lake during 1994-2005 (Tables 3-1 through 3-4). Alewives were present in the lake soon after its creation, as documented by cove rotenone sampling in 1972 and 1973 (Barwick and Harrell 1997), and occur in Kerr Reservoir and occasionally in the Dan River downstream from Belews Lake (Rohde et al. 2003). However, the taxonomic identification of al ewife collected during impingement sampling was not verified. In 2007, Duke researchers captured blueback herring, a species previously not found in th e lake. It is possible that th e fish identified as alewives may have been blueback herring, due to the morphological similarity of the two species.

Spotted bass have never been identified as occurring in Belews Lake, either by Duke Energy or NCWRC. The single 140-mm specimen collected during impingement sampling was not retained for taxonomic veri fication. It may have been a largemouth bass that was misidentified because of its damaged condition.

No federally or state-listed species were impi nged. In addition to fish, the invertebrate Asiatic clam ( Corbicula ), crayfish, and a freshwater mussel were found in impingement collections (Table 4-6).Impingement Mortality

4-4 Seasonal Patterns and Fish Size

Impingement rates were highest from late fall through the spring, November to early June, and lowest in summer and early fall, mid-June through October (Figure 4-1 and Table 4-7). This seasonal impingement pa ttern reflected the impingement rates for bluegill (Figure 4-2) because of its dominan ce in the impingement collections. The peak impingement rate for all species combined occurred on 2 January 2007 at 23.0 fish per 1,000 m 3 of water withdrawn. Bluegill accounted for 96 percent of this peak impingement event.

Impinged bluegill ranged in size from 48 to 139 mm total length (TL). Based on their observed length frequency distribution and lite rature values on age-length relationships for bluegill (Table 4-8), more than two-thir ds of the impinged bluegills were yearling or older fish (Table 4-9). Yearling or older fish comprised the majority of bluegills impinged from November through March, wh ile young-of-year (YOY) fish from the 2005 year class were more common in the spri ng collections, April-Ju ne (Figure 4-2).

Threadfin shad were impinged throughout the year, but peak impingement occurred in February-March and early August (Figure 4- 3). These periods of peak impingement involved both YOY and yearling or older fish; overall, ne arly half of the impinged threadfin shad were estimated to be year ling or older fish, but the probable age of approximately 12 percent of those collected could not be determined due to physical damage (Table 4-9). Impinged threadfin sh ad ranged in length from 33 to 120 mm TL (Figure 4-3).

Seven largemouth bass appeared in the impinge ment collections and ranged in size from 48 mm TL and 1.2 g to 237 mm TL and 124 g. They were impinged during the summer and fall (Figure 4-4). The majority (six fish or 86 percent) were considered to be YOY fish (Table 4-9).

Five impinged channel catfish were collect ed, ranging in size from 100 mm TL and 7.4 g to 190 mm TL and 64 g. One fish was collect ed per month during the months of May, July, November, December, and February (Figure 4-5). All were considered to be yearling or older fish (Table 4-9).

There was an unusually high frequency (269 of 975 collected fish or 27.6 percent) of fish collected that were judged to have died previous to the 24-h impingement collection period based upon their decomposed state a nd extensive fungal growth. The great majority (75 percent) were bluegill, but othe r species included alewif e, channel catfish, largemouth bass, redbreast sunfish, threadfin shad, and white perch. Some could not be identified beyond genus ( Lepomis ) or family (herring), or were totally unidentified because of their extremely poor condition. These previously dead fish may have remained on the fixed screen panels during the washing prior to the start of the 24-h collection or have been near the screens pr ior to the collection pe riod. They were not included in the analysis or impingement estimates.4-5 The seasonality of impingement for species ot her than the four species discussed above can be summarized as follows (Table 4-7):

Gizzard shad—November Redbreast sunfish—year-round Redear sunfish—September Redeye bass—April-May and August Spotted bass—March-April White perch—September-October

Variables Affecting Impingement Rates

Three categories of variables potentially affecting impingement rates are discussed: environmental variables, species-specifi c abundance, and spatial distribution.

Environmental Variables

Three potentially important environmental vari ables that could affect impingement rates are water temperature, dissolved oxygen concen tration (DO), and lake level or elevation. Mean daily water temperature records from the BCSS intake and daily lake level data were available for the sampling period from 25 April 2006 to 11 April 2007. DO readings were made by MACTEC sampli ng crews at the intake on the day of impingement sampling, generally in the morning between 0900 h and 1100 h.

The mean daily intake temperature va ried seasonally from a low of 53.2 o F on 19 February 2007 to a high of 92.7 o F on 5 August 2006 (Figure 4-6). The lake level varied only 1 ft (0.3 m) during the 12-month sampli ng interval, with a maximum elevation of

724.8 ft above mean sea level and a minimum el evation of 723.8 ft above mean sea level (amsl). What little change in elevati on did occur was primarily limited to summer months, June-September (Figure 4-6). Full pond is 725 ft amsl. DO readings on impingement sampling days also showed little seasonal variat ion, ranging from 5.98 mg/L on 10 May 2006 to 10.73 mg/L on 24 May 2006 (Figure 4-6).

Peak impingement rates for all species comb ined occurred on 2-3 January 2007 (Figure 4-6). This was a period of declining water temperatures prior to the minimum temperature being reached in mid-February. On 2 January 2007, the mean daily water temperature at the intake was 60 o F and the DO concentration was 7.4 mg/L (Figure 4-6). Neither of these readings would indicate stre ssful conditions. The la ke level on this date was 724.7 ft, which was typical for this period and near full pond (Figure 4-6).

The peak impingement on 2-3 January 2007 almo st exclusively consisted of bluegill of various ages and sizes (Figur e 4-7). While most impingeme nt of yearling and older bluegill occurred from November through Marc h, the temperature, DO, and lake level on 2 January did not appear to be the immedi ate cause for the impingement spike. Youngof-year bluegill (YOY) impingement also was higher on this date, but for this age groupImpingement Mortality

4-6 there was another period of p eak impingement in May and early June when temperatures were rising (up to 72-82 o F) and DO levels were fluctuat ing from 6.0 to 10.7 mg/L (Figure 4-7). It would appear that the increased impingement rates for bluegill observed on these

dates were related to factors other than temperature, DO level, and lake level.

Threadfin shad, the other species dominating impingement collections , experienced peak impingement on 27-28 February 2007 (YOY fish) and 27-28 March 2007 (yearling and older fish). On these dates, water temperat ures were beginning to rise from the winter minimum, but DO and lake levels were st able (Figure 4-8). Mean daily water temperature was 60.2 o F on 27-28 February and 56.1 o F on 27-28 March. DO concentration was 7.4 mg/L on 27-28 Februa ry and 8.2 mg/L on 27-28 March. The lake level was 724.6-724.7 ft amsl on these dates, i. e., near full pond. As with bluegill, the peak impingement events for threadfin sh ad were not obviously related to water temperature, DO, or lake level as poten tially controlling or stressful factors.

Species-Specific Abundance and Spatial Distribution

The electrofishing surveys conducted by Duke during 1996-2005 provide data on the relative abundance of fish species in Belews Lake, which can be compared to the 2006- 2007 impingement data to provide insight into the role of species- specific abundance and spatial distribution on the susceptibility of species to impingement at BCSS. Based on this comparison, it appears that the abundance of an individual sp ecies influences its susceptibility to impingement. Impingeme nt at BCSS was totally dominated by two species—bluegill and threadfin shad. These two species accounted fo r 94 percent of the impinged fish collected in 2006-2007 and also we re the two most abundant species in the 1996-2005 electrofishing catches for the entire la ke (Table 4-10). While impingement of other species was very limited (<11 specimens per taxon collected), th e third and fourth most frequently impinged species, redbreast sunfish and largemouth bass, were also

ranked third and fourth in relative abundance among species captured by electrofishing.

Two relatively common fish species, yellow perch and white crappi e (ranked sixth and eighth in the lake), were not found in impi ngement collections (Table 4-10). Their absence may be related to their spatial distri bution in the lake, indi cated by their reduced catch in the lower lake than in upper and middle regions (see Sec tion 3). Overall low impingement levels during 2006-2007 may be res ponsible for the absence of several less abundant species, simply by chance.



### Annual Losses

Impingement sampling during 2006-2007 provides a single year’s esti mate of seasonal and annual impingement at the BCSS intake, an d the best available estimate of current impingement for several reasons. Data collected by the 2006-2007 monitoring program and ongoing electrofishing sampli ng are representative of th e current relative abundance of fish species near the intake and thei r susceptibility to impingement. In 2006-2007, station operation was consistent with its fore casted use as a baseload facility, with4-7 cooling water flow rates of approximately 90 percent capacity. The monitoring program design encompassed complete diel and seasona l cycles of impingement, and the program

was conducted with strict adherence to Standard Operating Procedures.

Two alternative approaches to estimating th e current levels of impingement are: (1) “Normal Operations” representing recent hi storical and projected operation of the facility, and (2) “Full Oper ations” representing the full design capacity for water withdrawals by the facility. Normal Operati ons would be an estimated annual total of 9,638 impinged fish weighing 57.8 kg (Table 4-3 in Section 4). An estimate for Full Operations can be derived by substituting the design capacity for cooling water flow rates (1,454 MGD) rather than actual mean daily flow rates recorded during the 12-month sampling interval. Impingement losses under full operation are estimated to total 10,924 fish weighing 65.3 kg (Table 4-11). These to tals represent a 13 pe rcent increase in the numbers and biomass of impinged fish over Normal Operations

.

Annual Variability

Data collected by the 2006-2007 monitoring pr ogram are representative of current conditions, especially the relativ e abundance of fish species in the vicinity of the intake and their susceptibility to impi ngement. The data can be interpreted in the context of the existing conditions. Seasonal and annual vari ability in impingement mortality could occur if cooling water intake operation, lake level, water temperatures, DO concentration,

or fish abundance varied to a significant degree.

Intake Operation

BCSS is operated as a baseload facility, with an average annual capacity factor of 74 percent during 2002-2007 (Section 2). The aver age annual intake flow rate over this period was 79 percent of the maximum design ca pacity. BCSS is expected to continue to operate as a baseload facility, so the in fluence of cooling water flow rates on the variability of annual impingement rates should be minimal.

Intakes flows generally were highest during May-October (Table 2- 1), coinciding with the period of highest electricity demand. With the exception of May and early June when YOY threadfin shad were impinged, impinged fi sh densities were th e lowest recorded during 2006-2007 at BCSS (Figure 4-6). This inverse relationship between intake flow rates and observed impingement densiti es helps to reduce annual impingement.

Environmental Variables

Impingement rates during 2006-2007 did not appear to be influenced by water temperatures, lake levels, or DO concentr ations. However, these variables might influence impingement rates in future years.Impingement Mortality

4-8 Fish Abundance

The abundance, species composition, and size co mposition of fishes in Belews Lake and near the BCSS cooling water in take may vary annually as th e result of changing habitat suitability, trophic dynamics, reproductive success, interspecific competition, or several other factors. These changes could affect impi ngement rates at the intake, particularly if the majority of impinged fish are YOY and th e strength of successive year classes of YOY fish typically are volatile. Some annua l variability would appear random while some may reflect long-term trends in th e abundance of individual species.

Comparison of Annual Monitoring Programs

The results of two or more annual monitoring programs conducte d at the facility can be compared to evaluate inter-annual variabili ty. However, impingement at BCSS has not been studied in the past, so no hist orical information is available.4-9 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr 0 5 10 15 20 25 Weekly Impingement Rates for All Species Combined

2006 - 2007Impingement Rate per 106m3

Figure 4-1 Seasonal Pattern of Impingement Rates for All Species CombinedImpingement Mortality

4-10 0 5 10 15 20 25 30 35 40 45 0 10 20 30 40 50 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr

0 5 10 15 20 Impingement Rates by Age

Young-of-Year Yearling & Older

Undetermined 

### Bluegill

2006 - 2007Impingement Rate per 106m3

Length FrequencyPercent inLength Interval

Midpoint of Lengt h Interval (cm)

Figure 4-2 Seasonal Impingement Pattern and Length Frequency of Impinged Bluegill4-11 0 5 10 15 20 25 30 35 40 45 0 10 20 30 40 50 60 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr

0 1 2 3 4 5 Impingement Rates by Age

Young-of-Year Yearling & Older

Undetermined 

### Threadfin shad

2006 - 2007Impingement Rate per 106m3

Length FrequencyPercent in Length Interval

Midpoint of Length Interval (cm)

Figure 4-3 Seasonal Impingement Pattern and Length Frequency of Impinged Threadfin
ShadImpingement Mortality

4-12 

### 0 5 10 15 20 25 30 35 40 45 0 5 10 15 20 25 30 35 40 45 50 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr

0 1 2 3 4 5 Impingement Rates by Age Young-of-Year Yearling & Older

Undetermined 

### Largemouth bass

2006 - 2007Impingement Rate per 106m3



### Length FrequencyPercent in Length Interval



### Midpoint of Length Interval (cm)

Figure 4-4 Seasonal Impingement Pattern and Length Frequency of Impinged Largemouth Bass4-13 

### 0 5 10 15 20 25 30 35 40 45 0 5 10 15 20 25 30 35 40 45 50 Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr

0 1 2 3 4 5 Impingement Rates by Age Young-of-Year Yearling & Older

Undetermined 

### Channel catfish

2006 - 2007Impingement Rate per 106m3



### Length FrequencyPercent in Length Interval



### Midpoint of Length Interval (cm)

Figure 4-5 Seasonal Impingement Pattern and Length Frequency of Impinged Channel
CatfishImpingement Mortality

4-14 

### 722 723 724 725 726

4/1/2006 6/1/2006 8/1/2006 10/1/2006 12/1/2006 2/1/2007 4/1/2007 

### 0 5 10 15 20 25

DateImpingement Rate per 106m3 

### 40 50 60 70 80 90 100Mean Intake Temp. (OF) 

### 0 2 4 6 8 10 12 14 16

Dissolved Oxygen)Dissolved Oxygen (mgL-1)

ElevationElevation (ft-msl)

Figure 4-6 Daily Lake Level, Dissolved Oxygen Concentration, and Intake Water Temperature vs. Impingement Rate for All Species Combined, April 2006-April 20074-15 

### 722 723 724 725 726

0 2 4 6 8 10 12 14 16 18 20

4/1/2006 6/1/2006 8/1/2006 10/1/2006 12/1/2006 2/1/2007 4/1/2007 

### 0 1 2 3 4 5 6 7 8 9 10

YOYYAO Impingement Rate per 106m3

DateYOY Impingement Rate per 106m3 

### 40 50 60 70 80 90 100Mean Intake Temp. (OF) 

### 0 2 4 6 8 10 12 14 16

Dissolved OxygenDissolved Oxygen (mgL-1)

ElevationElevation (ft-msl)

YAO

Figure 4-7 Daily Lake Level, Dissolved Oxygen Concentration, and Intake Water Temperature vs. Impingement Rate for Young-of-Year (YOY) and Yearling and Older (YAO) Bluegill, April 2006 – April 2007Impingement Mortality

4-16 

### 722 723 724 725 726

0 1 2 3 4 5 6

4/1/2006 6/1/2006 8/1/2006 10/1/2006 12/1/2006 2/1/2007 4/1/2007 

### 0 1 2 3 4

YOYYAO Impingement Rate per 106m3

DateYOY Impingement Rate per 106m3 

### 40 50 60 70 80 90 100Mean Intake Temp. (OF) 

### 0 2 4 6 8 10 12 14 16

Dissolved OxygenDissolved Oxygen (mgL-1)

ElevationElevation (ft-msl)

YAO

Figure 4-8 Daily Lake Level, Dissolved Oxygen Concentration, and Intake Water Temperature vs. Impingement Rate for Young-of-Year (YOY) and Yearling and Older (YAO) Threadfin Shad, April 2006 – April 20074-17 Table 4-1 Impingement Sampling Dates and Time at BCSS during 2006-2007

Sampling Dates Sampling Interval (24-h) 25-26 April 2006 1004-1334 9-10 May 2006 1000-1404 23-24 May 2006 1000-1412

7-8 June 2006 0857-1345

20-21 June 2006 1030-1350 4-5 July 2006 0800-1330 18-19 July 2006 0827-1335 1-2 August 2006 0815-1325 15-16 August 2006 0810-1325 29-30 August 2006 0815-1320 12-13 September 2006 0830-1315 26-27 September 2006 0835-1320 10-11 September 2006 0820-1315 24-25 September 2006 0820-1305

7-8 November 2006 1030-1340

21-22 November 2006 0805-1135

5-6 December 2006 0820-1305

19-20 December 2006 0815-1100 2-3 January 2007 0820-1305 16-17 January 2007 0815-1305 30-31 January 2007 0815-1320 13-14 February 2007 0810-1100 27-28 February 2007 0815-1245

13-14 March 2007 0830-1310

27-28 March 2007 0815-1010 10-11 April 2007 0810-1045Impingement Mortality

4-18 Table 4-2 Fixed Screens Sampled for Impingement, by Unit and Sampling Date, 2006-2007

Unit 1 Unit 2

Screen 1A 1B 1C 1D 2A 2B 2C 2DDate Sampled 25-Apr-06 1 1 1 1 1 1
9-May-06 1 1 1 1 1 1 1 1
23-May-06 1 1 1 1 1 1 1 1

7-Jun-06 1 1 1 1 1 1 1

20-Jun-06 1 1 1 1 1 1 1 1

4-Jul-06 1 1 1 1 1 1 1 1

18-Jul-06 1 1 1 1 1 1 1 1
1-Aug-06 1 1 1 1 1 1 1 1
15-Aug-06 1 1 1 1 1 1 1 1
29-Aug-06 1 1 1 1 1 1 1 1
12-Sep-06 1 1 1 1 1 1 1 1
26-Sep-06 1 1 1 1 1 1 1 1

10-Oct-06 1 1 1 1 1 1 1 1

24-Oct-06 1 1 1 1 1 1 1

7-Nov-06 1 1 1

21-Nov-06 1 1 1 1 1 1 1 1

5-Dec-06 1 1 1 1 1 1 1 1

19-Dec-06 1 1 1 1 1 1

2-Jan-07 1 1 1 1 1 1 1 1

16-Jan-07 1 1 1 1 1 1 1 1

30-Jan-07 1 1 1 1 1 1 1 1

13-Feb-07 1 1 1 1 1 1 1 1

27-Feb-07 1 1 1 1 1 1 1 1

13-Mar-07 1 1 1 1 1 1 1 1

27-Mar-07 1 1 1 1

10-Apr-07 1 1 1 1 1 1 1 1

Times Sampled: 23 24 25 25 25 25 22 24

Samples per Unit 97 96

Sampled/Analyzed 1

pumps off4-19 Table 4-3 Estimated Total Number and Biom ass of Fish Impinged at BCSS, 19 April 2006 – 18 April 2007

Unit 1 Unit 2 Total

Species No. Wt. (g) No. Wt. (g) No. Wt. (g)

Alewife 32 141 64 536 96 676
Gizzard shad 12 3,613 0 0 12 3,613
Threadfin shad 592 2,859 1,037 3,080 1,628 5,939 Unidentified clupeid 0 0 13 110 13 110 Unidentified cyprinid 0 0 14 11 14 11
Channel catfish 26 261 40 1,007 67 1,268 White perch 0 0 13 125 13 125
Redbreast sunfish 43 911 106 1,876 149 2,786

Green sunfish 14 113 13 84 27 197 Bluegill 2,708 14,016 4,728 24,251 7,436 38,268
Redear sunfish 0 0 14 2,286 14 2,286 Hybrid sunfish 14 25 14 36 28 61

Sunfishes 14 0 0 0 14 0 Lepomis sp. 0 0 14 0 14 0 Largemouth bass 27 77 69 1,817 96 1,894 Spotted bass 12 359 5 156 18 516
Total 3,494 22,375 6,145 35,376 9,638 57,751Impingement Mortality

4-20 Table 4-4 Total Number and Percent Composition of Fish Collected at BCSS, 25 April 2006 – 11 April 2007

Unit 1 Unit 2 Total Species No. % No. % No. %

Alewife 2 0.79 5 1.10 7 0.99

Gizzard shad 1 0.40 - - 1 0.14

Threadfin shad 44 17.46 75 16.52 119 16.86 Unidentified clupeid - - 1 0.22 1 0.14 Unidentified cyprinid - - 1 0.22 1 0.14

Channel catfish 2 0.79 3 0.66 5 0.71 White perch - - 1 0.22 1 0.14

Redbreast sunfish 3 1.19 8 1.76 11 1.56

Green sunfish 1 0.40 1 0.22 2 0.28 Bluegill 194 76.98 351 77.31 545 77.20

Redear sunfish - - 1 0.22 1 0.14 Hybrid sunfish 1 0.40 1 0.22 2 0.28 Lepomis sp. - - 1 0.22 1 0.14

Sunfishes 1 0.40 - - 1 0.14 Largemouth bass 2 0.79 5 1.10 7 0.99 Spotted bass 1 0.40 - - 1 0.14

Total 252 100.00 454 100.00 706 100.00

Table 4-5 Total Biomass and Percent Composit ion of Fish Collected at BCSS, 25 April 2006 – 11 April 2007

Unit 1 Unit 2 Total Species Wt. (g) % Wt. (g) % Wt. (g) %

Alewife 10 0.59 43 1.64 52 1.23

Gizzard shad 293 17.76 - - 293 6.90

Threadfin shad 214 12.95 205 7.90 419 9.86 Unidentified clupeid - - 8 0.32 8 0.20 Unidentified cyprinid - - 1 0.03 1 0.02

Channel catfish 20 1.19 72 2.79 92 2.17 White perch - - 10 0.37 10 0.22

Redbreast sunfish 65 3.94 142 5.45 207 4.87

Green sunfish 8 0 6 0.25 15 0.34 Bluegill 1,004 60.87 1,810 69.68 2,814 66.26

Redear sunfish - - 163 6.29 163 3.85 Hybrid sunfish 2 0.11 3 0.10 4 0.10 Lepomis sp. - - - - - - Sunfishes - - - - - - Largemouth bass 6 0.34 135 5.19 140 3.30 Spotted bass 29 1.75 - - 29 0.68
Total 1,649 100 2,597 100.00 4,247 100.004-21 Table 4-6 Number and Percent Composition of Taxa Other Than Fish at BCSS, 25 April 2006 – 11 April 2007

Taxon Count Percent Biomass (g) Percent

Corbicula 341 98.55 747 89.88 Crayfish 4 1 80 9.58

Freshwater mussel 1 0 5 0.54

Total 346 100 831 100Impingement Mortality4-22Table 4-7 Estimated Total Number and Biomass of Fish Impinged Monthly at both Units of BCSS, 19 April 2006 – 18 April 2007January February March April May JuneSpecies CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g)Alewife 20 182 15 131 9 82 0 0 0 0 3 3Gizzard shad 0 0 0 0 0 0 0 0 0 0 0 0Threadfin shad 116 528 306 718 366 1,655 155 1,089 39 257 31 109Unidentified clupeid 0 1 13 110 0 0 0 0 0 0 0 0Unidentified cyprinid 0 0 0 0 0 0 0 0 2 2 12 10Channel catfish 0 0 13 72 0 0 1 12 13 158 0 0White perch 0 0 0 0 0 0 0 0 0 0 0 0Redbreast sunfish 8 128 5 86 25 494 12 12 5 9 33 338Green sunfish 0 0 0 0 0 0 0 0 0 0 0 0Bluegill 1,487 7,401 500 3,729 377 1,918 470 1,917 1,362 6,032 517 1,860Redear sunfish 0 0 0 0 0 0 0 0 0 0 0 0Hybrid sunfish 0 0 0 0 0 0 2 4 26 57 0 0Lepomissp.0 0 0 0 0 0 0 0 0 0 0 0Sunfishes 0 0 0 0 0 0 0 0 2 0 12 0Largemouth bass 0 0 0 0 0 0 0 0 0 0 3 5Spotted bass 0 0 0 0 14 415 3 100 0 0 0 0Total 1,630 8,240 852 4,845 792 4,564 642 3,134 1,449 6,515 610 2,3264-23Table 4-7 continuedJuly August September October November DecemberSpecies CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g)Alewife 10 11 0 0 0 0 3 9 30 213 6 45Gizzard shad 0 0 0 0 0 0 0 0 12 3,430 1 183Threadfin shad 171 433 256 479 53 74 54 322 23 103 59 171Unidentified clupeid 0 0 0 0 0 0 0 0 0 0 0 0Unidentified cyprinid 0 0 0 0 0 0 0 0 0 0 0 0Channel catfish 14 902 0 0 0 0 0 0 15 94 11 31White perch 0 0 0 0 1 7 12 118 0 0 0 0Redbreast sunfish 35 663 14 806 0 0 12 224 1 25 0 0Green sunfish 0 0 0 0 1 10 26 187 0 0 0 0Bluegill 175 942 113 650 197 1,174327 1,754 859 5,077 1,054 5,814Redear sunfish 0 0 0 35 14 2,251 0 0 0 0 0 0Hybrid sunfish 0 0 0 0 0 0 0 0 0 0 0 0Lepomissp.0 0 9 0 5 0 0 0 0 0 0 0Sunfishes 0 0 0 0 0 0 0 0 0 0 0 0Largemouth bass 38 58 28 90 11 1,342 3 335 12 61 1 4Spotted bass 0 0 0 0 0 0 0 0 0 0 0 0Total 442 3,009 420 2,059 281 4,858437 2,949 951 9,003 1,131 6,248Impingement Mortality4-24Table 4-7 continuedAllSpecies CountBiomass(g)Alewife 96 676Gizzard shad 12 3,613Threadfin shad 1,628 5,939Unidentified clupeid 13 110Unidentified cyprinid 14 11Channel catfish 67 1,268White perch 13 125Redbreast sunfish 149 2,786Green sunfish 27 197Bluegill 7,436 38,268Redear sunfish 14 2,286Hybrid sunfish 28 61Lepomissp.14 0Sunfishes 14 0Largemouth bass 96 1,894Spotted bass 18 516Total 9,638 57,7514-25Table 4-8 Maximum Total Length (mm) Used to Distinguish Young-of-Year from Yearling Fish by MonthSpecies Age Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecThreadfin shad 0 75 75 75 75 80 5055 60 65 70 75 751 95 95 95 95 100 8585 90 95 95 95 95Channel catfish 0 80 80 80 90 100 11050 60 70 80 80 801 180 180 180 185 190 195125 145 165 180 180 180Bluegill 0 65 65 65 65 7075 30 45 60 65 65 651 110 110 110 110 120130 85 95 105 110 110 110Largemouth bass 0 165 165 165 180 20580 110 135 155 165 165 1651 265 265 265 270 280230 235 245 255 265 265 265Note: shaded month indicates appearance of new year classSources: Cornish and Welke (2004), Pierceet al. (2003), Carlander (1977), Johnson (1970)Impingement Mortality

4-26 Table 4-9 Estimated Annual Impingement of Fish by Age Group at both Units of BCSS, 19 April 2006 – 18 April 2007

Young-of-Year Yearling & Older Undetermined

Species Count Percent Count Percent Count Percent

Alewife 0 0 0 0 96 100

Gizzard shad 0 0 0 0 12 100

Threadfin shad 599 36.77 837 51.42 192 11.81 Unidentified clupeid 0 0 0 0 13 100 Unidentified cyprinid 0 0 0 0 14 100

Channel catfish 0 0 67 100 0 0 White perch 0 0 0 0 13 100

Redbreast sunfish 0 0 0 0 149 100

Green sunfish 0 0 0 0 27 100 Bluegill 2,235 30.06 5,138 69.1 63 0.84

Redear sunfish 0 0 0 0 14 100 Hybrid sunfish 0 0 0 0 28 100 Lepomis sp. 0 0 0 0 14 100

Unidentified sunfishes 0 0 0 0 14 100 Largemouth bass 82 85.92 13 14.08 0 0 Spotted bass 0 0 0 0 18 100
Total 2,916 30.25 6,056 62.83 667 6.924-27 Table 4-10 Comparison of Relative Abundance of Fish Species in the 1996-2005 Electrofishing Surveys for all Sampling Transects Combined in Belews Lake and the 2006-2007 BCSS Impingement Collections

Electrofishing 2006-2007 Impingement

Species Total No. % Rank Total No. % Rank
Bluegill 16,831 48.729 1 545 77.195 1

Threadfin shad 4,552 13.179 2 119 16.856 2

Redbreast sunfish 3,747 10.848 3 11 1.558 3
Largemouth bass 1,594 4.615 4 7 0.992 4

Redear sunfish 1,576 4.563 5 1 0.142 9 tie
Yellow perch 1,444 4.181 6
White perch 903 2.614 7 1 0.142 9 tie
White crappie 835 2.417 8
Common carp 655 1.896 9
Hybrid sunfish 530 1.534 10 2 0.283 7 tie

Satinfin shiner 517 1.497 11

Gizzard shad 340 0.984 12 1 0.142 9 tie

Green sunfish 279 0.808 13 tie 2 0.283 7 tie
Black crappie 279 0.808 13 tie

Channel catfish 213 0.617 15 5 0.708 6

Warmouth 125 0.362 16

Golden shiner 53 0.153 17

White catfish 15 0.043 18 tie

Flat bullhead 15 0.043 18 tie
Pumpkinseed 15 0.043 18 tie

White sucker 7 0.020 21

Brown bullhead 4 0.012 22
Notchlip redhorse 3 0.009 23 tie

Flathead catfish 3 0.009 23 tie

Fathead minnow 2 0.006 25

Golden redhorse 1 0.003 26 tie

Snail bullhead 1 0.003 26 tie
Eastern mosquitofish 1 0.003 26 tie

Alewife - 7 0.992 5
Cyprinidae - 1 0.142 9 tie
Clupeidae - 1 0.142 9 tie
Lepomis sp. - 1 0.142 9 tie
Spotted bass - 1 0.142 9 tie

Unidentified sunfishes - 1 0.142 9 tie

Total 34,540 100.00 706 100.000Impingement Mortality4-28Table 4-11 Estimated Total Number and Biomass of Fish Impinged Monthly at both Units of BCSS for Full Flow Operations, 19 April2006 – 18 April 2007January February March April May JuneSpecies CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g)Alewife 22 204 16 142 11 94 0 0 0 0 4 4Gizzard shad 0 0 0 0 0 0 0 0 0 0 0 0Threadfin shad 130 592 332 779 485 2,303 208 1,441 41 267 34 122Herring/shad 0 1 14 118 0 0 0 0 0 0 0 0Cyprinidae 0 0 0 0 0 0 0 0 3 2 13 11Channel catfish 0 0 14 78 0 0 1 13 13 159 0 0White perch 0 0 0 0 0 0 0 0 0 0 0 0Redbreast sunfish 8 143 6 98 28 555 13 13 6 10 34 342Green sunfish 0 0 0 0 0 0 0 0 0 0 0 0Bluegill 1,665 8,285 547 4,065 512 2,561 580 2,387 1,393 6,166 559 2,015Redear sunfish 0 0 0 0 0 0 0 0 0 0 0 0Hybrid sunfish 0 0 0 0 0 0 2 5 26 57 0 0Lepomissp.0 0 0 0 0 0 0 0 0 0 0 0Largemouth bass 0 0 0 0 0 0 0 0 0 0 4 6Spotted bass 0 0 0 0 22 623 6 186 0 0 0 0Unidentified sunfishes 0 0 0 0 0 0 0 0 2 0 12 0Total 1,825 9,226 929 5,280 1,057 6,137 812 4,045 1,483 6,661 661 2,5014-29Table 4-11 continuedJuly August September October November DecemberSpecies CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g) CountBiomass(g)Alewife 10 11 0 0 0 0 5 13 41 260 6 51Gizzard shad 0 0 0 0 0 0 0 0 13 3,891 1 209Threadfin shad 171 433 256 479 53 75 60 364 35 169 65 190Herring/shad 0 0 0 0 0 0 0 0 0 0 0 0Cyprinidae 0 0 0 0 0 0 0 0 0 0 0 0Channel catfish 14 902 0 0 0 0 0 0 17 106 12 32White perch 0 0 0 0 1 7 13 126 0 0 0 0Redbreast sunfish 35 663 14 806 0 0 12 241 1 29 0 0Green sunfish 0 0 0 0 1 10 27 193 0 0 0 0Bluegill 175 942 113 650 197 1,176375 2,029 1,1316,651 1,181 6,498Redear sunfish 0 0 0 35 14 2,251 0 0 0 0 0 0Hybrid sunfish 0 0 0 0 0 0 0 0 0 0 0 0Lepomissp.0 0 9 0 5 0 0 0 0 0 0 0Largemouth bass 38 58 28 90 11 1,342 3 400 14 68 1 4Spotted bass 0 0 0 0 0 0 0 0 0 0 0 0Unidentified sunfishes 0 0 0 0 0 0 0 0 0 0 0 0Total 442 3,009 420 2,059 281 4,861495 3,366 1,25311,175 1,266 6,984Impingement Mortality4-30Table 4-11 continuedAllSpecies CountBiomass(g)Alewife 115 779Gizzard shad 14 4,101Threadfin shad 1,871 7,213Unidentified clupeid 14 119Unidentified cyprinid 16 13Channel catfish 70 1,290White perch 14 133Redbreast sunfish 158 2,902Green sunfish 28 203Bluegill 8,427 43,425Redear sunfish 14 2,286Hybrid sunfish 28 62Lepomissp.14 0Largemouth bass 99 1,967Spotted bass 28 809Unidentified sunfishes 14 0Total 10,924 65,3035-1 

# 5

ASSESSMENT OF ADVERSE ENVIRONMENTAL
IMPACT

Introduction

Section 316(b) of the Clean Wa ter Act calls for use of the “...best technology available to minimize adverse environmental impact.” In 2004, EPA issued the Phase II Rule which addressed implementation of §316(b) for existi ng cooling water intake structures that have a design flow of more than 50 MGD. As a result of challenges to this Rule by several groups, the U.S. Court of Appeals fo r the Second Circuit reviewed the Rule and remanded several key provisions on 25 January 2 007 (see Section 1). As a result of this remand, EPA issued a suspension of the Phase II Rule on 9 July 2007 and directed that “Permit requirements for cooling water intake structures at Phase II facilities should be established on a case-by-case best pr ofessional judgment (BPJ) basis.”

Prior to the Phase II Rule, BPJ compliance w ith §316(b) was based on a determination of whether or not the cooling water intake stru cture was resulting in adverse environmental impact (AEI). With the remand of the Phas e II Rule, this approach continues to be appropriate in BPJ determinations. Unfo rtunately, neither the Act nor subsequent guidance provided by the EPA provides any definition of the term “adverse environmental impact (AEI)” for use by permit writers in making their BPJ determinations. Consequently, it is left up to the permitting authority to determine what constitutes adverse environmental impact to be minimized under §316(b).

In this analysis, Duke Energy will evaluate the potential for an a dverse impact of the BCSS cooling water intake structure as a result of an unacceptable reduction in:

 biological integrity as meas ured in terms of aquatic community species composition, diversity, and functiona l organization; or

 human use of the aquatic resources in the source waterbody, especially fishing opportunity or catch quantity or quality.

These two evaluation criteria are consiste nt with both EPA’s original draft 316(b) guidance (EPA 1977) as well as histor ical practice (Dey et al. 2000).

Duke proposes to use multiple lines of i nvestigation to determine the potential for unacceptable adverse impacts by evaluating:Assessment of Adverse Environmental Impact

5-2  potential ecosystem impacts by:

o conducting a prospective evaluation ba sed on losses to impinged species

o conducting a retrospective evaluation ba sed on analysis of long-term data base, and

 impacts to human use by:

o estimating economic losses from impingement.

How do we go about assessing the risk of a dverse environmental impact for BCSS? Recognizing the need for a consistent and technically sound approach to assessing the potential effects of a wide variety of an thropogenic stresses on ecosystems, the EPA began an intensive effort to develop an a pproach for ecological risk assessment during

the late 1980s. The intent of this effort wa s to develop an approach that would parallel

that used for human health risk assessme nt but focus on the non-human ecosystem. These efforts, which were independent of those to re-promulgate §316(b) regulations, resulted in the publication of a “Framework for Ecological Risk Assessment” (ERA) in 1992 (EPA 1992). Following considerable public review, input and debate, “Guidelines for Ecological Risk Assessment” (ERA Guidelines) was finalized in October 1998 (EPA 1998).

These Guidelines replace the earlier framework, describe general principles, and give examples of how ecological risk assessment can be applied to a wide variety of systems, stressors, and spatial and temporal scales. The general principles reflect an effort to promote consistency in assessing ecological risk among EPA’s offices and regions, while at the same time permitting development of site-specific methods to meet local needs. EPA’s ERA approach has been used to a ddress a variety of chemical, physical, and biological stressors, as well as the combined effects of multiple stressors, across many agencies throughout the United States.

EPA defines ecological risk assessment as “... a process that evaluates the likelihood that adverse ecological effects may occur or are occurring as a result of exposure to one or more stressors” (EPA 1992). Since entrainm ent and impingement result in the exposure of aquatic organisms to physical and chemical st resses, it seems that a logical approach to assessing the risk of adverse environmenta l impact of cooling water withdrawals as required by §316(b) would be through the use of an ecological risk assessment framework, such as th at provided by EPA.

As noted above, the risk of adverse envir onmental impact from the continued operation of the BCSS cooling water intake system need s to be addressed from two perspectives: ecosystem (i.e., biological in tegrity) and human (i.e., fishing opportunity). Potential adverse effects from these two perspectives were addressed within the framework of an ecological risk assessment as described in EPRI (2002). The results of these two assessments are then used together as part of a “weight-of-evidence” approach to5-3 determine the overall risk of adverse envir onmental impact from the BCSS cooling water

intake structure on Belews Lake.



### Assessment of Ecosystem Effects

EPA recognized that it is unlikely that risk can be accurately determined through use of a single measure. Therefore, the ecological risk assessment framework calls for careful review of all information relevant to the issue under a “multiple lines of evidence” approach to risk assessment. These line s are independently as sessed using two broad categories of methods: prospective and retr ospective methods. Prospective methods attempt to predict the effects of a stressor, such as cooling water withdrawal, on the ecological endpoints selected for the assessm ent. Retrospective methods, on the other hand, evaluate the potential effects of an exis ting stressor, such as a cooling water intake structure, by measuring the actual effects on th e ecological endpoints. In this assessment, we use a combination of prospective and retr ospective methods to determine the potential ecosystem effects of cooling water withdrawals at BCSS.

Prospective Approach

EPA defines use of prospective methods for ecological risk assessment as “an evaluation

of the future risks of a stre ssor not yet released into th e environment or of future conditions resulting from an existing stre ssor” (EPA 1998). For this assessment, prospective methods entail predicting the pot ential consequences of impingement at BCSS on the fish community composition and function and on recreational fishing in

Belews Lake.

As described in Section 4, impingement mon itoring studies were conducted at BCSS over the period April 2006 – April 2007. The results of these studies were used to estimate the expected annual impingement at BCSS under normal operations:

Species Total Average Weight per Individual (g) Count Biomass (g)

Bluegill 7,436 38,268 5.1

Threadfin shad 1,628 5,939 3.6

Redbreast sunfish 149 2,786 18.7

Alewife 96 676 7.0

Largemouth bass 96 1,894 19.7

Channel catfish 67 1,268 18.9

Hybrid sunfish 28 61 2.2

Green sunfish 27 197 7.3

Spotted bass 18 516 28.7

Cyprinidae 14 11 0.8

Lepomis sp. 14 0 0.0

Redear sunfish 14 2,286 163.3Assessment of Adverse Environmental Impact

5-4 Unidentified sunfishes 14 0 0.0

Herring 13 110 8.5

White perch 13 125 9.6

Gizzard shad 12 3,613 301.1

Total 9,638 57,751 6.0

Mean weights per fish suggest that most, if not all, of the fish collected were juveniles and most likely were either age 0 or age 1. Only for redear sunfish (14 impinged) and gizzard shad (12 impinged) would those i ndividuals impinged be considered adults.

All but two of the taxa collected had estimat es of annual impingement that averaged less than one fish every other day. Given that all of these species are common to Belews Lake, it is hard to image that the removal of one individual or less of each species every other day, most likely juvenile s, could be considered an adverse environmental impact from Belews Lake, a lake of more than 3,800 acres (1,560 ha).

Bluegill, the species with the highest estimat ed annual impingement, is one of the most

abundant fish found in littoral areas of the lake and is a popular panfish target of anglers. The estimated annual impingement of this spec ies represents a removal rate of less than twenty individuals per day. Most of these we re likely less than 2 years old. Assuming a conservative total mortality rate of 50 per cent per year, these 20 juveniles would survive to be about five average-sized harvestabl e adult (i.e., 7.5 in. long and 4 years old). Hence, the current annual impingement of bluegi lls is equivalent to the removal of five adult bluegill per day. As with the other specie s, it is hard to imagine that such a removal rate would constitute an adverse environmental impact on Belews.

The other species commonly impinged, thread fin shad, is abundant throughout the pelagic areas of Belews Lake. The estimated annual impingement of this species represents a removal rate of le ss than five individuals per day. Most of these were likely less than 1 year old. At 3.6 grams each, this re moval rate translates to an annual removal rate of less than 2 grams of biomass per surf ace acre of Belews Lake per year. Given the rapid growth, short life span, and high reproductive potential of this species, it is hard to imagine that such removal rates can have any detectable effect s on either population persistence for this species or on the amount of food availa ble to support higher trophic

levels.

Retrospective Approach

Within the ecological risk assessment framework, a retrospective assessment of risk is an evaluation of the causal linkages between observed ecological effects and stressors present in the environment (EPA 1998b). For this assessment, the stressor would be the

loss of fish from the Belews Lake commun ity caused by impingement at the CWIS. The retrospective approach evaluate d whether effects on individual species populations or the community as a whole are apparent by exam ining trends in the species richness and5-5 relative abundance of individual species during the time that BCSS has operated. Community metrics involving species ric hness and abundance would be appropriate because impingement is equivalent to harv esting fish, without adding pollutants or altering the physical habitat of the lake, for which other community metrics might be appropriate.

Fortunately, there exists a database on the recent occurrence of fi sh species and their

relative abundance in the littoral zone of Belews Lake from 1996 to 2005, available from Duke’s annual spring electrofishing surveys. Trends in species richness and relative abundance should be apparent if operation of BCSS has had a discernable, progressive effect on the fish community in the lake over this 10-year period. If there are discernable effects, are they consistent with the selec tive loss of individual species to impingement that could be interpreted as being causal in nature?

Hypothetically, selective harv esting of fish species by impingement could result in species or trophic imbalance in the community, or reduced standing crops of fish. If true, metrics involving species richness, speci es composition, and relative abundance may reveal significant, sustained changes in sp ecies occurrence and a bundance, or a trophic imbalance. Also, a persistence or increase in top carnivores (piscivo res) might indicate stability or improvement in the community, and vice versa.

Surveys were conducted once per year by Duke in the spring from 1995 to 2005, daylight when water temperatures were between 15 o C and 20 o C (Coughlan et al. 2006). Twenty 300-m shoreline transects (five up-lake, five mid-lake, and 10 down-lake) were selected to represent existing habitat type s. The results of these surveys are discussed in terms of fish abundance, species richness, and trophic st ructure of the fish community as follows.

Fish Abundance

In the littoral zone of Belews Lake, there appears to be a trend of increasing fish abundance over the period from 1996 to 2005 (Figure 5-1). The total spring electrofishing catch should reflect the a nnual abundance of fish since the sampling methodology and intensity has remained constant from year to year (Section 3). The total annual catch in 1996-2000 ranged from 2,100 to 2,735 fish, then began to increase in 2001 to 3,668 fish and peaked at 6,127 fish in 2004 (Figure 5-1). This trend of increasing catch or fish abundance was observed in all regi ons of the lake (see Tables 3-3 and 3-4 in Section 3), but particularly so in the lower region (Table 3-4).

The trend of increasing total catch is mostly a reflection of the increasing abundance of bluegill (Figure 5-2), the numeri cally dominant species in th e lake. Threadfin shad, the second most common species, was especially abundant in the 2004 catch (Figure 5-2), adding to the peak total catch observed in that year (Figure 5-1). Largemouth bass and channel catfish, the remaining target species , also were relatively abundant in 2004, but showed no overall trend during the 10-year period (Figure5-2).Assessment of Adverse Environmental Impact

5-6 Species Richness

While the abundance of fish appears to be increas ing in recent years, there has been little change in species richness in the littoral zone of the whol e lake (combined upper, middle, and lower regions) from 1996 to 2005. There ha ve been regional differences in species composition, however, as noted in Section 3.

The total number of species caught annually in the entire lake varied between 17 in 1999 and 21 in 1996 and 2003 (Figure 5-3). Species consistently caught in all annual surveys were bluegill, channel catfish, common carp, gizzard shad, green sunfish, largemouth bass, redbreast sunfish, redear sunfish, sa tinfin shiner, threadfin shad, warmouth, and white crappie, white perch, and yellow perch (F igure 5-4). In contra st, some species only were caught in only a single year, such as brown bullhead and eastern mosquitofish (2003), fathead minnow (2000), and golden redhorse (1996), likel y due to their relatively

low abundance or distribution in areas not readily sampled by electrofishing.

Trophic Structure

Species were divided into trophic guilds c onsisting of insectivore, omnivore, and piscivore (Table 5-1). Insectivores were dominant in electrofishing surveys, ranging from 51.5 to 84.8 percent (Figure 5-5). Omnivor es and piscivores al ternated annually as the second-most abundant troph ic guild in the lake. Omnivores comprised 3.8 to 33.7 percent of the fish community, and piscivor es ranged from 7.6 to 33.1 percent of the community. There was no consistent trend in the relative abundance of each of the three guilds from 1996 through 2005.

Retrospective Summary

Recent data (1996-2005) from electrofishing in the littoral zone of Belews Lake do not indicate any changes in the fish community that could be linked to the destabilizing effects of impingement losses at BCSS. Inst ead, the data show a sustained increase in fish abundance since 1996, particularly for the do minant species, bluegill. Other indices, species richness and trophic structure, show a relatively stable fish community in terms of its composition and trophic dynamics.

The fish community of Belews Lake since the mid-1980s has been recovering from the effects of selenium contamination (see Section 3). The 1996-2005 electrofishing data may be showing the continuation of this r ecovery, where the fish community composition has reached some stability but individual populat ions continue to expand. This recovery is occurring despite the continuing operat ion of BCSS and any impacts potentially resulting from impingement losses.5-7 

### Effects on Human Uses

Belews Lake, from which BCSS withdraws its cooling waters, provides important recreational fishing opportunities to people fr om North Carolina and adjacent states. Popular targets of anglers incl ude largemouth, several species of catfish, and a variety of panfish species including bluegill, crappie, and yellow perch. In addition, the lake supports a healthy community of other water-dependent species that provide passive use opportunities such as nature watching. He nce, in addition to potential effects on biological integrity, it is reasona ble to address the potential e ffects of impingement of fish

at BCSS on human uses of Be lews Lake, including fishing.

Two different types of measures of the pot ential effects of impingement on human uses of the aquatic resources in Belews Lake, e quivalent loss and economic value, were used in this analysis. Estimates of the two types of measures were calcula ted for each of four target species: threadfin sha d, largemouth bass, bluegill, a nd channel catfish. Together, these four species comprised more than 95 percent of total impingement at BCSS. The methods and parameter values used to deve lop these two measures are discussed in Appendix A. The resulting m easures are described below.

Equivalent Loss Measures

Since impingement at BCSS involves several sp ecies of fish and in cludes a variety of sizes within each species, equivalent loss ca lculations provide a means to express these losses in biological terms that are more amenable to interpretation. In this assessment, two different equivalent loss measures were estimated for each target species:

 Equivalent yield provides a measure of th e additional weight of each species that could have been harvested by anglers in the absence of any impingement at BCSS.

 Production foregone provides a measure of the additional biomass production that could have resulted from the impinged indi viduals in the absence of any impingement

at BCSS.

Using the methodology and the most probable es timates for each of the input parameters described Appendix A, estimates of equivale nt fishery yield and production foregone for each of the four target species were genera ted using the monthly impingement estimates at BCSS. The monthly estimates were then summed to calculate total annual values.

Three of the four target species evaluated in this assessment, largemouth bass, bluegill and channel catfish, directly support fisheries in Belews Lake. Annual fishery yield that could result from the fish impinged at BCSS totaled 108 lb (49.0 kg) under actual cooling water flows during the course of the impingement monitori ng program and 121 lb (54.9 kg) under maximum (design) cooling water flows (Table 5-2). Most (> 93 percent) of this equivalent yield was through bluegill.Assessment of Adverse Environmental Impact

5-8 Annual production from the ta rget species impinged at BCSS totaled 730 lb (331.1 kg) under actual cooling water flows and 887 lb (402.3 kg) under maximum cooling water flow (Table 5-3). Most (>91 percent) of this production foregone was through bluegill.

In the absence of impingement at BCSS, this additional production could support additional biomass of fish targeted by fi shermen and provide energy to support other ecosystem functions.

Economic Value

Calculation of economic value takes the es timates of equivalent yield and production foregone described above and assigns economic value based estimates of “willingness to pay” for additional resources by the users of that resource. As such, this measure provides another perspective on the issue of adverse environmental impact by weighing the estimates of equivalent loss by the rela tive “importance” of each species assigned by

humans. Calculation of economic value has a long history of use including for the assignment of economic benefits of the Phase II rulemaking (EPA 2004).

In this assessment, economic values were a ssigned to each of the four categories of benefit values relevant to §316(b) re gulations for existing facilities:

 market direct use benefits;

 nonmarket direct use benefits;

 indirect use be nefits; and,

 non-use benefits.

The value of marketed goods is equivalent to the sum of predicted changes in “consumer and producer surplus.” Producer surplus is the difference between the price obtained for a good (e.g., fish) and the cost of producing that commodity. Consumer surplus is the difference between the perceived value of a good or service to the consumer and the cost of acquiring that good or service. Non-ma rketed goods, such as recreational fishing, normally require using indirect markets, such as travel, to infer their value. In addition, some positive changes in resources such as forage fish might increase indirectly the direct use values even though the resources themselv es are not directly used. Finally, in

addition to these direct and indirect use-related values , there is a potential for environmental changes to increase the welfar e of individuals who do not use the resource

at all. These latter benefits are consider ed non-use benefits. Me thods and input values

used to calculate economic values for each of these benefits categories are described in Appendix A.

Total annual economic value for all fish impinged at BCSS totaled only $883 under actual cooling water flow and only $994 under ma ximum cooling water flow (Table 5-4). Most of this economic value (~62 percent) was as a result of th e direct loss of bluegill.5-9 Uncertainty in Economic Value

Given the large number of parameters needed to calculate economic values, coupled with the difficulty in obtaining precise estimates of the input values for each parameter, there can be considerable uncertainty in the es timates of economic value generated for any individual facility. It is for this reas on that EPA guidance on conducting such economic

evaluations recommends that an uncertaint y analysis be conducted as part of the evaluation (EPA 2000b). The purpose of such an uncertainty analysis is to make transparent all the underlying s ources of uncertainty in the calculation of economic value such that the reader can independently de termine whether the results have sufficient precision and accuracy to meet regulatory needs.

In this report, uncertainty wa s addressed using two methods. First, sensitivity analysis was conducted on key input parameters to determine the relative importance of the uncertainty in the values for each parameter to the estimates of economic value. Second, Monte Carlo analysis was used to evaluate the cumulative uncertainty in the estimates in economic benefit combining the uncertainty in each of the input parameters. For simplicity, this uncertainty analysis focuse d on the estimates of economic benefit based on actual cooling water flows. Uncertainty for the maximum cooling water flow case

should be almost identical. Results for each of the two methods are discussed below.

The results of sensitivity analysis are illustra ted in Figure 5-6. Uncertainty in recreational price per pound yielded the grea test range in estimates of annual economic value (-63 to +210 percent) while uncertainty in the fishi ng mortality rate yielde d the second greatest range (-13 to +88 percent). Uncertainty in these two parameters was clearly the most important in determining the total uncertainty in the estimate of annual economic value. Uncertainty in the remaining seven input pa rameters (natural mo rtality rate, fishing vulnerability, weight, release rate, post-release survival, trophic conversion factor, and equivalent predatory exploitati on rate) had relatively minor effects on estimates of annual economic value (< + 40 percent).

The results of the Monte Carlo analysis are illustrated in Figure 5-7. The frequency distribution of the resulting annual estimates appeared generally symmetrical, although

most of the estimates of economic value resu lting from this uncertainty analysis were higher than the most probable estimate (Figur e 5-7). The median value from the Monte Carlo analysis was 78 percent higher than th e most probable estimate while the 25th and 75th percentiles were 39 percent and 131 per cent higher, respectiv ely. There was less than a 10 percent chance that the true annual economic bene fit was more than twice the most probable estimate reported in Table 5-4. The fact that most of the estimates of economic value were higher than the most pr obable estimate is likely related to the nonsymmetrical effects of the two key parame ters, the recreational price per pound and the fishing mortality rate, described above.Assessment of Adverse Environmental Impact

5-10 

### Conclusions

The results of this assessment provide no evidence that impingement at BCSS is causing

effects within Belews Lake that rise to a level that could be c onsidered an “adverse environmental impact.” This conclusion is based on a careful evalua tion of all relevant lines of evidence including the following observations:

1. Numbers of fish lost as a result of im pingement are exceedingly small compared to likely sizes of fish populations in Be lews Lake. For all but two species,

removal rates amounted to less than one fish every other day. For bluegill, removal rates were equivalent to five adults per day; likely less than or similar to the daily harvest by a single angler.

2. Total number impinged each year for threadfin shad amounted to a biomass removal rate of less than 2 grams per surf ace acre of Belews Lake per year. This species is a highly prolific spawner with high growth ra te and short life span. This high reproductive potential can easil y compensate for the relatively small losses at BCSS with no long-term effects.

3. Electrofishing data from 1996-2005 do not indicate any changes in the fish community that could be linked to the de stabilizing effects of impingement losses at BCSS. Instead, the data show a sust ained increase in fish abundance since 1996 and a relatively stable fish commun ity in terms of its species richness, species composition, an d trophic structure.

4. The fish community since the mid-1980s has been recovering from the historic

effects of selenium contamination. Recen t data appear to show the continuation of this recovery, despite the conti nuing operation of BCSS and any impacts potentially resulting from impingement losses.

5. Estimates of total fishery catch that c ould result from the fish impinged at BCSS had they survived amount to only 108 lb (49 kg) per year, most of which was bluegill. This level of harvest is less th an what would be expected annually from a few anglers.

6. Estimates of the total production foregone as a result of fish impinged at BCSS amounted to less than 730 lb (331 kg) per ye ar of biomass. Most of this was a result of bluegill, an abunda nt species in Belews Lake.

7. The best estimate of the total economic value of fish impinged at BCSS was $883 per year. Even considering the uncertainty in these estimates, it is highly unlikely that the economic value exceeds $1,700 per year. These values must be considered trivial compared to the total economic value of the recreational fishery

in Belews Lake.5-11 1996 1998 2000 2002 2004 2,000 3,000 4,000 5,000 6,000 7,000Total Catch

Figure 5-1 Total Annual Catch of Fish in Belews Lake, 1996-2005Assessment of Adverse Environmental Impact

5-12 1996 1998 2000 2002 2004 0 500 1,000 1,500 2,000 2,500 3,000 3,500Bluegill 0 50 100 150 200 250Largemouth bass 0 500 1,000 1,500 2,000Threadfin shad 0 10 20 30 40Total CatchChannel catfish

Figure 5-2 Mean Annual Catch of Bluegill, Largemouth Bass, Threadfin shad and Channel Catfish in Belews Lake Using Boat Electrofishing Sampling, 1996-20055-13 1996 1998 2000 2002 2004 0 5 10 15 20 25 30Total No. of Species

Figure 5-3 Total Number of Fish Species Found in Annual Electrofishing Surveys of Belews Lake, 1996-2005Assessment of Adverse Environmental Impact

5-14 Species 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Gizzard shad

Threadfin shad
Common carp

Fathead minnow

Golden shiner

Satinfin shiner

Golden redhorse

Notchlip redhorse

White sucker

Brown bullhead

Channel catfish

Flat bullhead

Flathead catfish

Snail bullhead

White catfish

White perch

Eastern mosquitofish

Redbreast sunfish

Green sunfish

Pumpkinseed

Bluegill

Redear sunfish

Hybrid sunfish

Warmouth

Largemouth bass

Black crappie

White crappie

Yellow perch

Total No. of Species 22 19 20 17 20 19 19 22 20 19

Figure 5-4 Species Composition in Belews Lake, 1996-20055-15 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 0 10 20 30 40 50 60 70 80 90 100Percent Trophic Level Composition % Insectivore % Omnivore % Piscivore

Figure 5-5 Percent Composition of Fish Trophic Guilds in Belews Lake, 1996-2005Assessment of Adverse Environmental Impact5-16Recreational PriceExploitation RateTrophic ConversionWeightRelease SurvivalRelease rateFishing MortalityVulnerabilityNatural Mortality-200 -150 -100 -50 0 50 100 150 200Percent DifferenceFigure 5-6 Estimates of the Range of Effects of Uncertainty inEach Input Parameter on Estimates of Annual Economic Benefit atBCSS5-17020406080100-300 -250 -200 -150 -100 -50 0 50 100 150 200 250 3000510152025
Percent FrequencyPercent Difference from Estimate Cumulative PercentFigure 5-7 Results of Monte Carlo Analysis of Uncertainty in Key Input Parameters on Estimates of Annual Economic Benefits atBCSSAssessment of Adverse Environmental Impact

5-18 Common Name Trophic
Guild

Gizzard shad O

Threadfin shad O
Common carp O

Fathead minnow O

Golden shiner O

Satinfin shiner I

Golden redhorse I
Notchlip redhorse I

White sucker O

Brown bullhead O

Channel catfish O

Flat bullhead I

Flathead catfish P

Snail bullhead I

White catfish O
White perch P
Eastern mosquitofish I

Redbreast sunfish I

Green sunfish I
Pumpkinseed I
Bluegill I

Redear sunfish I
Hybrid sunfish I
Largemouth bass P

Warmouth I
Black crappie P
White crappie P
Yellow perch P

Source: NCDENR (2006)

P = Piscivore

I = Insectivore/Invertivore

O = Omnivore

H = Herbivore

Table 5-1 Trophic Guild Assignments for Fish Species in Belews Lake5-19 Table 5-2 Estimates of Potential Total A nnual Equivalent Fishery Yield (lb) from Individuals Impinged for Each Target Species at BCSS

Species Annual Fishery Yield (lb)

Actual Flow Maximum Flow

Threadfin shad 0 0

Channel catfish 1 1

Bluegill 101 115

Largemouth bass 6 6

Total 108 121

Table 5-3 Estimates of Potential Total Annua l Production Foregone (lb) from Individuals Impinged for Each Target Species at BCSS

Species Annual Production Foregone (lb)

Actual Flow Maximum Flow

Threadfin shad 24 27

Channel catfish 12 13

Bluegill 671 823

Largemouth bass 23 24

Total 730 887Assessment of Adverse Environmental Impact

5-20 Table 5-4 Estimates of Economic Value of Fish Impinged at BCSS

Species Total Impingement Value (2008$)

Actual Flow Maximum Flow

Threadfin shad a 0 0

Channel catfish 0 0

Bluegill 543 615

Largemouth bass 34 35

Equivalent predator b 267 301

Non-target species c 38 43

Total 883 994

a Economic benefits for threadfin shad only occur th rough forage benefits to the equivalent predator.

b Equivalent biomass production for all Target Species converted to an equivalent biomass of a recreationally important predator (largemouth bass).

c Economic value associated with all impinged fish s pecies that were not selected as target species.6-1 

# 6

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Allen, M.S., C.J. Walters, and R. Myers. 2008. Temporal trends in largemouth bass mortality, with fishery implications. North American Journal of Fisheries Management 28: 418-427.

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Coughlan, D.J., K.A. Finley, and J.J. Hall. 2006. Assessment of balanced and indigenous populations in Belews Lake, for Belews Creek Steam Station: NPDES No. NC0024406. Duke Energy, Huntersville, North Carolina. August 2006.

Dey, W. P., S.M. Jinks and G.J. Lauer. 2000. Th e 316(b) assessment process: evolution towards a risk-based approach. Environmen tal Science and Po licy (3): S15-S23.

Dey, W.P. 2002. Use of equivalent loss models under Section 316(b) of the Clean Water Act. The Scientific World. 2(S1): 254-270.

Duke Power (Duke). 2001. Assessment of balan ced and indigenous populations in Belews Lake

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Heidinger, R.C. 1975. Life hi story and biology of the largemout h bass. Pages 11-20 In: R.H. Stroud and H. Clepper (eds.). Black Bass Biology and Management. Sport Fishing Institute, Washington, D.C.

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Hining, K. 2003. Characteristics of the black an d white crappie populations in Belews Lake, 2001-2002. Final report. Mountain Fisheries Investig ations. Federal Aid in Fish Restoration Project F-24. North Carolina Wildlife Resources Commission, Division of Inland Fisheries. Raleigh, NC.

Holland-Bartels, L.E. and M.C. Duval. 1988. Variations in abunda nce of young-of-the-year channel catfish in a navigation pool of the U pper Mississippi River. Transactions of the American Fisheries Society. 117:202-208.

Hubert, W.A. 1999. Biology and management of channel catfish. Pages 3-22 In: E.R. Irwin, W.A. Hubert, C.F. Rabeni, H.L. Schramm, Jr ., and T. Coon (eds.). Catfish 2000:Proceedings of the International Ictalurid Symposium. Am erican Fisheries Society, Bethesda, Maryland.

Koel, T.M., R.M. Sparks, and R.E. Sparks. 1998. Channel catfish populations in the Upper Mississippi River System. Illinois Natural Hist ory Survey Reports, September-October 1998.

LeGrande, H.E. Jr., S.E. McRae, S.P. Hall, a nd J.T. Finnegan. 2008. Natural Heritage Program list of the rare animal species of North Caro lina. North Carolina Natural Heritage Program, N.C. Department of Environment and Natura l Resources, Division of Natural Resource Planning and Conservation.

Lemly, A.D. 1993. Teratogenic eff ects of selenium in natural popul ations of freshwater fish. Ecotoxicology and Environmental Safety 26:181-204.6-3 Lemly, A.D. 2002. Symptoms and im plications of selenium toxic ity in fish: the Belews Lake case example. Aquatic Toxicology 57: 39-49.

McMahon, T.E. and J.W. Terrell. 1982. Habitat suitability index models: channel catfish. U.S.D.I. Fish and Wildlife Service. FWS/OBS-82/10.2 29 pp.

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Environmental Sciences Section. April 2005.

North Carolina Department of Environment and Natural Resources (NCDENR). 2006a. Roanoke River Basinwide Water Plan, Septem ber 2006. Division of Water Quality Basinwide Planning Unit. Raleigh, North Carolina.

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Paukert, C.P., D.W. Willis, and D.W. Gabelhouse, Jr. 2002. Effect and acceptance of bluegill length limits in Nebraska Sandhill lakes. North American Journal of Fisheries Management

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Pflieger, W.L. 1997. The Fishes of Missouri. Missouri Department of Conservation, Jefferson City, MO. 372 pp.

Pierce, C.L., C.S. Guy, M.A. Pegg, and P.J. Br aaten. 2003. Fish growth, mortality, recruitment, condition and size structure. Volume 4. Population structure and habitat us e of benthic fishes along the Missouri and Yellowstone rivers. U. S. Geological Survey, Cooperative Research Units, Iowa State University. Science Hall II, Ames, Iowa.

Pitlo, J., D. Dieterman, and G. Jones. 2004a. Largemouth bass ( Micropterus salmoides ). In: Pitlo, J.M. Jr. and J.L. Rasmussen (eds.). UMRRC Fisheries Compendium. 3rd Edition. Upper Mississippi River Conservation Committee. Rock Island, Illinois. January 2004. pp. 169-173.References Cited

6-4 Pitlo, J., K. Brummet, and M. Endris. 2004b. Channel catfish ( Ictalurus punctatus ). In: Pitlo, J.M. Jr. and J.L. Rasmussen (eds.). UM RRC Fisheries Compendium. 3rd Edition. Upper Mississippi River Conservation Committee. Ro ck Island, Illinois. January 2004. pp. 151-155.

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Rohde, F.C., R.G. Arndt, D.J. Coughlan, and S.M. Smith. 2003. An annotated list of the fishes known from the Dan River in Virginia and Nort h Carolina (Blue Ridge/Piedmont Provinces). Southeastern Fishes Council Proceedings 45:1-10.

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Facilities. Office of Water. EPA-821-F-06-007. June.A-1 

# A

APPENDIX A: METHODS TO ESTIMATE
EQUIVALENT LOSS AND ECONOMIC VALUE OF
FISH IMPINGED AT BELEWS CREEK STEAM
STATION

Introduction

This appendix describes the methods used to develop estimates of annual equivalent loss and economic value of fish impinged at the Be lews Creek Steam Station (BCSS). For this assessment, annual impingement estimates we re developed using recent impingement monitoring data collected at BCSS over the period 25 April 2006 – 11 April 2007 (Section 4).



### Estimates of Target Species Equivalent Losses

In order to calculate economic value, estimates of annual impingement loss at BCSS for the four target species (threadfin shad, larg emouth bass, bluegill, and channel catfish) must be converted to equivale nt measures that can be assi gned economic value for these species. For species of commercial and/or recreational importance, the equivalent measure selected was the yield to the fisher y that would have been expected had the individuals not been impinged. For species that serve as forage for other, generally larger, aquatic organisms, the measure select ed was the production of biomass available as food for higher trophic levels that would have been expe cted had the individuals not been impinged. Methods used in this re port to calculate these two measures are consistent with those used by EPA in the Phase II rulemaking and are described below.

The measure “yield to the fishery” is define d as the annual total yi eld (in weight) that

could have occurred in the commercial or r ecreational fishery from those individuals lost to impingement in the absence of compensatory changes in to tal mortality. This yield is calculated using the Equivalent Yield Model (EYM)

, which integrates Baranov’s catch equation (Ricker 1975) with estimates of the mean weight by age (Dey 2002, EPRI 2004). This method is conservative in that potential density-dep endent changes in mortality or growth rates th at often occur in natural popul ations were not included. Using the EYM, fishery yield equivalent to the annual impingement loss at BCSS for each target species was estimated as follows:Appendix A: Methods to Estimate Equivalent Loss and Economic Value of Impinged Fish At Belews Creek

SS

A-2 where:

EY = Equivalent yield to fishery

NL j = Number of each age or life stage category (j) lost annual to impingement

BCSS

S

j → i = Total survival from age or life stage category (j) to age (i)

n

j = Number of age or life stag e categories (j) impinged at BCSS

V

i = Vulnerability of age (i) to fishing

F

i = Instantaneous fishing mortality rate for age (i)

Z

i = Instantaneous total mortality rate for age (i)

A i = Total mortality rate for age (i) = 1-e-Zi

W

i = Average weight for individual of age (i) captured in the fishery

nf

= Maximum number of ages (i) vulnerable to fishery.

The EYM results in an estimate of yield define d in the same units used to describe the average weight of the individuals and integrates yield across all ages. In this assessment, the EYM was not applied to threadfin shad as it does not support any direct commercial or recreational fishing.

The measure of biomass production that could ha ve resulted from individuals impinged at BCSS was calculated using the Production Foregone Model (PFM) (Dey 2002, EPRI 2004). As with the EYM, this method is also conservative in th at potential densitydependent changes in mortality or growth ra tes that often occur in natural populations were not included. Using the PFM, potenti al biomass production from individuals impinged was estimated for each of the target species as follows: 

#    

   

###      

 f l n

i i i i

i i n

j i j j 

### Z F V W A S NL EY

1 1Appendix A: Methods to estimate equivalent loss and economic value of fish impinged at Belews CreeK

Steam STation

A-3 

#     

#  

i i Z G

i i n

j i j j L

i i Z G e W G S NL

P i i l

 

 

 

 

##   1

1

1

and the total production foregone (P) can be found by summing over all the age categories that are impinged:



# 

  m

i i P P

1

where:

P

= Total production foregone

P i = Production foregone for individuals impinged at the BCSS in age category (i)

G i = Instantaneous growth rate in weight for age category (i)

NL j = Number of each age category (j ) lost to impingement at BCSS

S

j → i = Total survival from age category (j) to age (i)

n

j = Number of age categories (j) impinged at BCSS

W

i = Average weight of indi viduals in age category (i)

Z

i = Average instantaneous mortality rate for age category (i)

m = Total number of age categories impinged at BCSS.

L = Final age category.

The PFM was applied to all target species th at as individuals serv e as food for other aquatic organisms during at leas t part of their life cycle.

Both the EYM and PFM are consistent with th e benefits calculation procedures used by EPA in their regional analys is of the benefits of th e Phase II Rule (EPA 2004b). Estimation of the biological input parameters for each of the target species is described

below.Appendix A: Methods to Estimate Equivalent Loss and Economic Value of Impinged Fish At Belews Creek

SS

A-4 Assignment of Age Categories for Impinged Individuals

One of the necessities of equivalent loss cal culation is that the direct measures of impingement mortality must be assigned to individual age categories as defined in the production foregone and equivalent yield models. In this assessment, age was assigned using length information for each target species obtained from the current impingement monitoring together with estim ates of maximum length at age for these same species

obtained from the scientific literature and from an analysis of the length-frequency patterns for each species.

Life Table Information

Biological input parameters for the Producti on Foregone and Equivalent Yield models include life stage durations, in stantaneous natural and fishin g mortality rates, and the fraction vulnerable to the fishery for each life stage and age, as well as mean weights at the beginning of each life stage and age for each target species. Each of these model inputs was determined as described below.

Life Stage Durations

Estimates of impingement were developed for this assessment on a monthly basis. Consequently, the duration of each month was set as 30.4 days, the average monthly duration across the entire year. However, it is important to rec ognize that fish do not become vulnerable to impingement until they ar e approximately 1 in. long and typically 1 to 2 months of age. Hence, the number of mont hly increments in the first year of life is less than 12. Spawning months and mont hs at which each species first became vulnerable to impingement at BC SS were assigned as follows:

Species Peak Spawning

Month Average Month
When Individuals

Reach 1 in. TL

Threadfin shad Mid-May Mid-July

Largemouth bass Late April Early June

Bluegill Early June Late August

Channel catfish Early Jun Mid-July

Natural Mortality Rates

A range (maximum, most probable, and minimum) of instantaneous natural mortality rates for each target species was obtained from the following sources:

Threadfin shad –Daily instantaneous natura l mortality rates were obtained from EPRI (2005) Table 4-43. For age 0, the most proba ble value was assumed to be the midpoint between the maximum and minimum values listed. For ages 1 and 2, maximum andAppendix A: Methods to estimate equivalent loss and economic value of fish impinged at Belews CreeK

Steam STation

A-5 minimum values were assumed to be 25 per cent higher and 25 per cent lower than the most probable value, respectively.

Largemouth bass – Most probable daily instan taneous natural mortality rates for Age 0

individuals were assumed to be the same as for the closely-re lated species, black crappie, obtained from EPRI (2005), Table 4-41. Ma ximum and minimum values were assumed to be 25 percent higher and 25 percent lower than the most probable value, respectively. Most probable daily instantaneous natural mo rtality rates for Ages 1+ were calculated from total mortality and exploitation rate s obtained from Allen et al. (2008).

Bluegill – Maximum and minimum daily instantaneous natural mortality rates for Age 0+

individuals were assumed to be the same as for the closely related species, black crappie, and obtained from EPRI (2005), Table 4-41. Most probable values were assumed to be at the mid-point between the maximu m and minimum values reported.

Channel catfish – Daily instantaneous natural mortality rates for Ages 0+, daily instantaneous natural mortality rates for all ages were obtained from EPRI (2005), Table

4-25.

These most probable values were used to provi de the best estimates of equivalent loss, while the maximum and minimum values were considered in the uncertainty analysis.

Fishing Mortality Rates

A range (maximum, most probable, and mini mum) of instantaneous fishing mortality rates for the two species that directly suppor t fishing were selected as follows:

Largemouth bass – Daily instantaneous fish ing mortality rates for Ages 2+ were calculated from total mortality and exploitation rates obtained from Allen et al. (2008). These instantaneous fishing mortality rates acco unted for fish that are caught and kept as well as those that are caught a nd released but subsequently di e from the stress of capture.

Bluegill – Most probable and maximum daily instantaneous fishing mortality rates for Ages 3+ were from Coble (1988) while th e minimum value was from Paukert et al. (2002).

Channel catfish – The maximum, most pr obable, and minimum daily instantaneous fishing mortality rates for Ages 5+ were assumed values based on annual fishing mortality rates of 0.15, 0.10, and 0.05 respectivel y, consistent with a lightly exploited

stock.

As with natural mortality, the most probabl e values were used to provide the best estimates of equivalent loss, while the maxi mum and minimum values were considered in the uncertainty analysis. Since there is little or no harvest of threadfin shad in Belews Lake, fishing mortality rates for this species were set to 0.Appendix A: Methods to Estimate Equivalent Loss and Economic Value of Impinged Fish At Belews Creek

SS

A-6 Fishing Capture Rates

The instantaneous rate of capture by the fisher y (Fc) is a measure of the rate fish are being caught. For all species except largemout h bass, all fish captu red by anglers that were caught by anglers were assumed to ha ve been kept. For those species, the instantaneous rate of capture is the same as th e instantaneous fishing mortality rate (F).

For largemouth bass, however, the fishery includ es of a high rate of catch and release. This purposeful release of live fi sh after capture demonstrates that for this species, it is the capture of the fish by recreat ional anglers that is valued and not merely the harvest of fish for consumption. Therefore for this specie s, the catch rate was assumed to be higher than the fishing mortality rate. In this asse ssment, estimates of the instantaneous rate of capture were calculated based on probabilities of release and probabilities of subsequent

survival as follows:

  

##  

365 1 ln 365      

 

  



RS R e

Fc F

where:

F

= Daily instantaneous fishing mortalit y rate determined as described above

R = Probability that a fish th at is caught will be released

RS = Probability that a fish caught and released will survive.

A range of values for the probabilities that a fish will be released and that it will subsequently survive were selected base d on best professional judgment following a

review of available scientific literature:

Range of Values Probability of

Release Probability of
Survival Following

Release

Maximum 0.50 0.30

Most probable 0.25 0.15

Minimum 0.18 0.05Appendix A: Methods to estimate equivalent loss and economic value of fish impinged at Belews CreeK

Steam STation

A-7 Fishing Vulnerability Rates

Fishing vulnerability rates refer to the frac tion of each age at a size vulnerable to be harvested by anglers. For the maximum and minimum fishing vulnerabi lity rates used in this assessment, individuals were assumed to be not vulnerable (rate = 0) up to a set age and completely vulnerable (rate = 1) above that age. The ag es of complete vulnerability were estimated using best professional judgm ent based on length at age information from the scientific literature. Resulting estimates are as follows:

Species Youngest Age of Vulnerability Oldest Age of Vulnerability

Largemouth bass 2 4

Bluegill 3 4

Channel catfish 5 6

For the most probable values, it was a ssumed that half of the population became vulnerable at the youngest age while the remain ing half became vulnerable at the oldest age. These most probable values were used to provide the best estimates of equivalent loss, while the maximum and minimum values were considered in the uncertainty analysis.

Weight at Beginning of Age

A range (maximum, most probable, and minimu m) of estimated weights at the beginning of each age were obtained for each target species from the following sources:

Threadfin shad – The most probable mean wei ght at the time of first impingement (Age 0) was assumed to be 1 g, while those for subsequent ages were obtained from Thompson et al. (2005). The maximum and minimum weights were a ssumed to be 20 percent higher and 20 percent lower than the most probable valu e, respectively.

Largemouth bass – The most probable mean wei ght at the time of first impingement (Age 0) was assumed to be 1 g. Most probable weights for Ages 1+ were estimates using lengths and a length-weight re lationship for largemouth bass in North Carolina presented in Carlander (1977). Maximum and minimum va lues for all ages were assumed to be 20 percent higher and 20 percen t lower than the most probable value, respectively.

Bluegill – The most probable mean weight at the time of first impingement (Age 0) was assumed to be 1 g, while the maximum a nd minimum values were assumed to be 20 percent higher and 20 percen t lower than the most probable value, respectively. Maximum, most probable and minimum weights for Ages 1+ were based on maximum, most probable and minimum lengths at age from Carlander (1977), Cornish and Welke (2004), and Heidinger and Waddell (1989), resp ectively, coupled with a length-weight relationship based on unpublished data.Appendix A: Methods to Estimate Equivalent Loss and Economic Value of Impinged Fish At Belews Creek

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A-8 Channel catfish – The most probable mean wei ght at the time of first impingement (Age 0) was assumed to be 1 g. Maximum and mi nimum values for this age were assumed to be 20 percent higher and 20 per cent lower than the most probable value, respectively. Maximum weights for Ages 1+ were base d on lengths at age from Heidinger and Waddell (1989) while the most probable and minimum weights were based on lengths at age from Pierce et al. (2003) coupled with a length-weight relationship from www.Fishbase.org

.

For all species, weights at the beginning of each month within an age were interpolated using an instantaneous growth rate based on the weights at the begi nning and end of that age. The most probable values were used to provide the best estimates of equivalent loss, while the maximum and minimum values were considered in the uncertainty analysis.



### Economic Valuation Methods

The potential economic values of impingement at BCSS were calculated for each of the benefit categories described using standard economic con cepts outlined in EPA (2004b, Part A: Evaluation Methods, Chapter A9: Be nefit Categories and Valuation). Methods

used to estimate values associated with each of the four benefit cat egories (market direct use benefits, non-market direct use benefits, indirect use benefits, and non-use benefits)

are discussed below.

Direct Use Values

Direct use values accrue to individuals who di rectly use the aquatic resources affected, in other words, commercial and recreational fisher men. The economic value of this benefit category is then equivalent to the economic value of the harvest by fishermen that would have resulted from the fish that were impi nged. The biological benefit values were defined in terms of pounds to be consistent with reported fishery economic statistics. Using these estimates of increased fishery harvest, the economic value of the direct use benefit category was estimated for each sub-component (market and non-market) as

follows.

Market Values (Commercial Fishing)

Market benefits refer to economic benefits that can be directly measured from data obtained in the marketplace. Changes in the magnitude of commercial fish and shellfish harvests are the principal market benefits relevant to §316(b) regulations. Since impingement losses at cooling water intake st ructures had the potential to increase stock size, and hence commercial harvests, positive market benefits could potentially accrue had they not been impinged. At present, co mmercial fishing on Bele ws Lake appears to

be non-existent. Hence for this assessme nt, the market value of any increase in commercial fishing was assumed to be essent ially non-existent and no further estimation of this category was required.Appendix A: Methods to estimate equivalent loss and economic value of fish impinged at Belews CreeK

Steam STation

A-9 Non-Market Direct Use Values (Recreational Fishing)

This category includes benefits derived through use of the resource that are not reflected

in the market for the resource. Relative to §316(b) regulations, the most common benefit that could accrue from impinged fish would be through increases in recreational fishing opportunities. Increased abundance of adult fish that could result had impingement

losses not occurred can lead to increased catch rates for indi vidual anglers as well as an

increase in the number of fishing trips by anglers.

Unfortunately, benefits from increased recreatio nal use of the resour ce are not directly reflected in the primary market, i.e., the mark et for recreational fishing. However, EPA

concluded that there is considerable liter ature to support valui ng this benefit through estimation of an angler’s “willingness to pa y” for recreational opportunities. Thus, the

non-market direct use value for additional recreational catch can be defined as the

increase in the total “willi ngness to pay” across all anglers resulting from any greater recreational opportunities due to reduction in impingement losses. The recreational values used represent the marginal bene fit per unit change in recreational catch.

For this assessment, total “willingness to pa y” for each target species was calculated by multiplying the estimated biological benefits (pounds) of impinged fish by the expected value per pound recreational a nglers were willing to pay for that increased harvest:

S S S RP BBR RFB  

where:

RFB S = Economic benefits ($) to recreationa l fishing for each target species (S)

BBR S = Biological benefits (lbs) to recreati onal fishing for each target species (S)

RP S = Value per pound anglers are willing to pay for the increase in harvest of the target species (S).

The biological benefits to the recreational fi shery for each target species estimated for BCSS (Table 5-2) are likely to be a very sma ll fraction of the estimated recreational catch of comparable species in Belews Lake in recent years. Hence, there is no reason to expect that changes in recreational fishing ha rvest that could result had the fish not been impinged at BCSS would be sufficiently large so as to affect the price the anglers are willing to pay. Therefore, the values that anglers are currently willing to pay for each species should be a reasonable measure of the values they would be willing to pay assuming impingement was eliminated. This is the same assumption used by EPA in calculating the national benefits of the Phase II Rule (EPA 2004b).

For this assessment, we used the same recreational values per fish as used by the EPA in the Phase III Rule (EPA 2006), which were th en adjusted to reflect current (2009$).Appendix A: Methods to Estimate Equivalent Loss and Economic Value of Impinged Fish At Belews Creek

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A-10 Each of the recreationally-caught target spec ies in this assessment falls into EPA’s panfish category. Values used in this assessment were:

Species Group Recreational Value (2009 $/fish)

Maximum Most Probable 3 Minimum

Bass 14.49 8.48 4.97

Panfish 1.82 0.99 0.54

To convert these values to a weight basis to be consistent with the biological benefits calculation, each of these recreational values was divided by an estimated average weight per harvested fish based on best professiona l judgment. The resulting average weights per fish that directly support re creational fishing are as follows:

Species Average Weight per Fish Harvested (lb/fish)

Maximum Most Probable Minimum

Largemouth bass 2.0 1.5 1.0

Bluegill 0.3 0.2 0.1

Channel catfish 3.0 2.0 1.0

The resulting values ($) per pound of fish for each target species are as follows:

Species Recreational Value (2009$/lb)

Maximum Most Probable Minimum

Largemouth bass 14.49 5.66 2.49

Bluegill 18.22 5.37 1.79

Channel catfish 1.82 0.54 0.18

The most probable values were used to provide the best estimates of equivalent loss while

the maximum and minimum values were c onsidered in the uncertainty analysis.

Indirect Use Benefits

This category includes benefits that accrue to humans fr om the use of the resource indirectly. Relative to §316(b) regulations, the indirect bene fit that could result from fish that were not impinged would be through an increased consumption by higher trophic levels of production that result from these organisms. This increased consumption could result in greater growth and survival rates among fish in these higher trophic levels, and hence, increase fishing opportunities. Pr oduction consumed by higher trophic levels

3 Used EPA’s mean value as most probable.Appendix A: Methods to estimate equivalent loss and economic value of fish impinged at Belews CreeK

Steam STation

A-11 results from pelagic forage species, such as threadfin shad, as well as individuals of recreationally important species th at die of natural causes.

Unfortunately, there are no generally accepted me thods to directly assign a value to this benefit. Instead, the value of this benefit is assigned indirectly by quantifying the amount of commercially and/or recr eationally important species th at could be supported by the production potentially generated by these impi nged organisms, which were subsequently harvested by man. Hence, the value of the production equivalent to the fish impinged is equal to the value of commerc ial and/or recreational harves t that could be supported by that production.

The value of the indirect benefits of impinge d fish at BCSS using the following three-step

process.

Step 1 – Estimation of Total Biomass of Higher Trophic Levels Supportable by the Annual Productivity Equivalent to the Impingeme nt. The total biomass of higher trophic levels supportable is calculated by usi ng a trophic transfer method as follows:



#   TTC

PFB HTB

S S 

###   

# 

 4

1

where:

HTB = Total annual higher trophic level biomass (pounds) supported by production foregone attributable to impingement

PFB S = Biomass production foregone for each target species (S) attributable to impingement

TTC = Trophic transfer coefficient.

This approach is identical to that used by EPA in the Section 316(b) Final Phase II Rule (EPA 2004b).

For this assessment, production foregone esti mates equivalent to impingement at BCSS for each of the target species were calcul ated using the Production Foregone Model as

described above and listed in Table 5-3. These estimates of production foregone were based on annual impingement estimates from BC SS. A trophic transfer coefficient of 10 percent, consistent with EPA (2004b), was then used to convert the total biomass forgone to an amount of higher trophic level biom ass supportable by that production foregone. The coefficient means that an average of 10 percent of the production foregone would have ended up as predator biomass. For th e uncertainty analysis, a range for the trophic transfer coefficient of 5 to 15 percent was assumed.

Step 2 – Estimation of Equivalent Pred ator Harvest Supporte d by Annual Productivity Equivalent to the Reduction in Impingement. As previously noted, the value of indirectAppendix A: Methods to Estimate Equivalent Loss and Economic Value of Impinged Fish At Belews Creek

SS

A-12 benefits is determined by the value of th e commercial and/or recreational harvest supported by the increased productivity. Hen ce, the total higher trophic level biomass estimated under Step 1 needs to be converted to an estimate of actual yield to the fishery expressed as equivalent predator harvest. This is accomplished by assuming that the total higher level biomass is converted to biom ass of a popular commercial or recreational species and then multiplying the value by the annual fishery exploitation rate for that species as follows:

EP ER HTB EPY  

where:

EPY = Equivalent predatory yield (pounds) attributable to target fish impinged

HTB = Higher trophic level biomass (pounds) at tributable to target fish impinged

ER EP = Fishery exploitation rate for th e selected equivalent predator.

For this assessment, largemouth bass was sele cted as the equivalent predator endpoint upon which the estimate of indirect value is ba sed. In reality, any potential production

increase would of course be transferred among many species, includ ing some with little or no recreational or commercial importan ce. However, this species is a common predator throughout Belews Lake where it is a popular target of anglers. Hence, this species should be a reasonably represen tative species for assigning recreational importance, and hence value, for this assessment. Using the life table information, the annual probability of capture for largemout h bass was estimated to be 60 percent, assuming a relatively intense fishery. For the uncertainty analysis , a range of 40 to 80 percent was assumed. We believe that th e selection of the largemouth bass as the equivalent predator provides a reasonably c onservative estimate of indirect-use value, since the “willingness to pay” (WTP) estimates for this species is at the upper boundary of the range of WTP values for other species addressed in this assessment.

Step 3 – Estimation of Indirect Use Economic Benefit. Estimates of the economic value of the increased recreational harvest resulting from increases in forage biomass were calculated using the methods previously desc ribed for direct-use non-market benefits. For this assessment, the value per fish for largemouth bass (the equi valent predator) was

assumed to be the same as described above.

Non-Use Benefits

As previously discussed, this category, al so known as passive use values, includes all benefits above and beyond any accrued through use of the resource. Most commonly

cited non-use benefits incl ude bequest and existence va lues. EPA acknowledges that these benefits can be estimated best by us ing contingent valuation methods on a sitespecific basis. However, they concluded th at such studies are un likely to be conductedAppendix A: Methods to estimate equivalent loss and economic value of fish impinged at Belews CreeK

Steam STation

A-13 for specific facilities and were clearl y beyond the scope and budget of EPA for development of the § 316(b) regulations (EPA 2004a).

In the final rule, EPA provided that "In cases where an impingement mortality and entrainment characterization study does not iden tify substantial harm to a threatened or endangered species, to the sustainability of populations of important species of fish, shellfish, or wildlife, or to the maintena nce of community structure and function in a facility's waterbody or watershed, monetiza tion [of non-use benefits] is not necessary." [69 Fed. Reg. Vol. 131 (9 July 2004) page 41648]. However, they do require a qualitative discussion of these benefits if they are believed to exist.

The fisheries monitoring studies described in Section 5 provide no evidence that impingement at BCSS is causing “substanti al harm” to threatened and endangered species or to aquatic populations and communities of the Belews Lake. Therefore, consistent with the EPA approach for the Section 316(b) Phase II Rule, non-use values

were not included in this economic valuation.

Adjustment for Other Species

The total annual economic bene fits for the target specie s is the sum of the annual economic benefits for all benefit categorie s described above. These target species, however, do not account for all fish impinge d at BCSS but only 95.7 percent. The following equation was used to account for th e benefits resulting from reductions in impingement for the remaining 4.3 percent of fish impinged at BCSS:



# 

        

  4

1 1 957

. 0 1

TS TS TS non Ben Ben

where:

Ben non-TS = Economic benefits accruing to non-target species

Ben TS = Economic benefits accruing to four target species and the equivalent predator.

The total annual economic value of fish imping ed at BCSS is the sum of the benefits to the target species plus the bene fit to the equivalent predator and the benefit to non-target species.



### Uncertainty Analysis

EPA’s Phase II §316(b) Rule requires that a faci lity seeking a site-specific determination

based on benefits valuation also submit “an an alysis of the effects of significant sources of uncertainty on the results of the study” [ §125.95(b)(6)(iii)(C)]. Un certainty refers to the lack of knowledge about measures and comp onents that go into each element of theAppendix A: Methods to Estimate Equivalent Loss and Economic Value of Impinged Fish At Belews Creek

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A-14 benefits valuation procedures. Under Phase II , the purpose of the uncertainty analysis is to make transparent all the underlying sour ces of uncertainty in the calculation of economic value such that the appropriat e regulatory authority can independently

determine whether the results have sufficient precision and accuracy to meet regulatory needs (EPA 2004b) and form sufficient basi s for sound regulatory decisions. The purpose of this section is to evaluate the eff ects of uncertainty in key input parameters on

the estimates of economic value for BCSS.

Uncertainty is not unique to the calculation of economic value under Phase II §316(b). Some uncertainty exists in almost all predic tions of future conditi ons based on past or existing information and this is especially tr ue when dealing with environmental science

and economic issues. In both environmental scien ce and economics, inhe rent variability and limited understanding of underlying proce sses, coupled with difficulty in making accurate measurements of underlying paramete rs, makes consideration of uncertainty in these cases especially important. Uncertain ty analysis is becoming an increasingly important part of cost-benefit assessments as they play a greater role in the environmental regulatory process.

EPA (2000) identified the following mini mum requirements applicable to most uncertainty analyses related to environmental regulations:

 To present the outcomes or conclusions base d on expected or most plausible values;

 To provide descriptions of all known key assumptions, biases, and omissions;

 To perform sensitivity analysis on key assumptions; and

 To justify the assumptions used in the sensitivity analysis.

Uncertainty arises in assessments from three general sources: natural variation, uncertainty in model structure, and uncertain ty in model parameters. Natural variation

results from natural differences across elem ents within a populat ion or in a population across time. For example, not all members of the United States population are expected

to value increased recr eational fishing opportunities to th e same degree. Alternatively, wide year-to-year differences in impingement densities at the same station are common.

These differences in abundance can result in large differences in the annual economic value. Both of these examples can yiel d uncertainty in the total economic value estimated under §316(b).

Uncertainty related to model stru cture arises from the lack of knowledge as to what is the most appropriate form of the model to accura tely describe the process being modeled. For example, the form of the relationship betw een the number of trips and travel cost in a simple travel cost model has been assumed to be linear, semi-log, or log by various analysts (Rosenberger and Loomis 2001). Howe ver, the most appropriate form is still a matter of debate. Likewise, alternatives that reduce total cooling water flow can result in reduced impingement. Most commonly, an assumption of a linear relationship with cooling water volume is made. However, this assumption also remains an area of debate.Appendix A: Methods to estimate equivalent loss and economic value of fish impinged at Belews CreeK

Steam STation

A-15 Finally, uncertainty in model parameters can re sult from difficulty in measurement or in inherent variability in the model parameter. This is likely to be the most frequently encountered source of uncertainty in econom ic valuation under the Phase II Rule. Examples of this source of uncertainty include estimates of life stage-specific life table parameters for equivalent loss estimation, estimates of the performance of the various CWIS alternatives, and measurements of a ngler’s “willingness to pay” obtained from

surveys.

In this section we address three broad areas of uncertainty: parameters used to estimate direct and indirect use benefits, questions regarding the use an d magnitude of non-use benefits, and the economic factors used to estimate the lifetime benefits, focusing primarily on uncertainty in model parameters. Each of these areas is discussed below.

Inputs to Direct and I ndirect Use Benefits

Key input parameters addresse d in this section include:

 Natural mortality rate,

 Fishing mortality rate,

 Recreational fishing release rate,

 Post-release survival rate,

 Age of recruitment to the fishery,

 Mean weight at beginning of each stage,

 Trophic conversion factor,

 Exploitation rate for equivalent predator, and

 Recreational value per pound.

Two other key input parameters, impingeme nt rates and age composition, were not addressed in this uncertainty analysis as reliable information on the uncertainty was

unavailable from the hi storical studies.

Uncertainty for this assessment was addressed by two means. First, a sensitivity analysis was conducted on individual input parameters . Second, a Monte Carlo analysis was conducted to determine the likely overall uncer tainty in the estimat es of annual economic value resulting from the current levels of uncertainty. The results of each of these analyses are provided below.

Sensitivity Analysis

A sensitivity analysis was conducted individua lly on each of the seven input parameters listed above. Multiple calculations of annual equivalent loss and economic value were made using the extreme values (i.e., maxi mum and minimum) for each parameter whileAppendix A: Methods to Estimate Equivalent Loss and Economic Value of Impinged Fish At Belews Creek

SS

A-16 holding all other parameters constant at their most probable values. The purpose of this sensitivity analysis was to determine the parameters for which the current levels of uncertainty have the greatest effect on each of the estimates.

Monte Carlo Analysis

Monte Carlo analysis was used to assess the ove rall uncertainty in the estimates of total annual equivalent loss and economic benefits ba sed on the current levels of uncertainty in each of the seven input parameters. For each of these parameters, random values were selected from a triangular di stribution, wherein the maxi mum and minimum values for

the distribution were set to the maximu m and minimum values for each parameter

described earlier and the mode of the distribution was set to the mid-point used as the best estimate for each parameter. Values for each parameter were randomly selected separately for each species and life stage and the Monte Carlo anal ysis was run using 1,000 iterations to define the resulting fre quency distribution in annual estimates of equivalent loss measures and economic benefit.