ALTERNATIVE INTAKE TECHNOLOGIES 

AT INDIAN POINT UNITS 2 & 3 

Attachment 6 

Attachment 6 

Biological Assessment 

Biological Effectiveness of Alternative Intake Technologies for Indian Point Units 2 and 3 

[LWB/AKRF/Normandeau/ASA] 

Appendix A: Biological Analysis of Selected Cooling System Alternatives for Indian Point 

Energy Center [ASA] 

Appendix B: Biological Evaluation of Intake Screen Alternatives to Reduce Impingement 

and Entrainment Losses at Indian Point Energy Center [Normandeau] 

Appendix C: Empirical Assessment of Expected Population-Level Effects of Reductions in 

Entrainment Losses at Entergy Nuclear Indian Point Units 2 and 3 [AKRF] 

Appendix D: Responses to Issues Raised in NYSDEC’s FEIS [LWB/AKRF] 
Biological Effectiveness of Alternative Intake 

Technologies for Indian Point Units 2 and 3 

Lawrence W. Barnthouse, Ph. D. 

LWB Environmental Services, Inc. 

Douglas G. Heimbuch, Ph. D. 

AKRF, Inc. 

Mark Mattson, Ph. D. 

Normandeau Associates, Inc. 

John R. Young. Ph. D. 

ASA Analysis and Communications, Inc. 

February 2010
i

Executive Summary 

Entergy Nuclear Indian Point 2, LLC and Entergy Nuclear Indian Point 3, LLC 

(collectively, “Entergy”) have submitted a timely and complete renewal application for a 

State Pollutant Discharge Elimination System (“SPDES”) permit for the Indian Point 

Entergy Center (“IPEC”) nuclear powered electric generating stations 2 and 3 

(individually, “Unit 2” and “Unit 3,” and collectively, the “Stations”). Counsel for 

Entergy informed Lawrence W. Barnthouse of LWB Environmental Services, Inc., 

Douglas G. Heimbuch of AKRF, Inc., Mark T. Mattson of Normandeau Associates, Inc., 

and John R. Young of ASA Analysis & Communication, Inc. (collectively the 

“Biological Experts”) that the New York State Department of Environmental 

Conservation (“NYSDEC” or “Department”) staff has proposed modifications in the 

Stations’ draft SPDES permit, including possible construction and operation of two large 

counter-flow, forced draft, plume abated hybrid cooling towers to be located on the 

eastern shoreline of the Hudson River at the IPEC site in Westchester County, New York 

(the “NYSDEC Proposed Project”). Counsel for Entergy also informed the Biological 

Experts that consideration of the NYSDEC Proposed Project is subject to an alternative 

technologies assessment, as directed by the NYSDEC Assistant Commissioner’s August 

13, 2008 Interim Decision. Accordingly, the Department may revisit its proposed 

modifications to the draft SPDES permit for the Stations and change them pursuant to 

Entergy’s alternative technologies assessment.1

This report supports the “Evaluation of Alternative Intake Technologies at Indian 

Point Units 2 & 3” prepared by Enercon Services, Inc (“ENERCON”). Entergy retained 

ENERCON and the Biological Experts to determine whether an alternative technology 

exists that “will minimize adverse environmental impact to a level equivalent to that 

which can be achieved by closed cycle cooling.” Interim Decision, at 25. According to 

the Interim Decision, this assessment must include “aquatic impact information, relevant 

cost information (for example, cost of construction, installation, and operation), and the 

proposed location of the technology at the site.” Id. at 26. The Interim Decision allows 

Entergy to provide “further information . . . with respect to the numbers of fish that are 

entrained and impinged at the Stations as part of the evaluation of alternative 

technologies.” Id. at 26, n.18. This supporting report provides evaluations of the 

“biological effectiveness” (discussed below) of the Stations’ existing intake technology, 

the NYSDEC Proposed Project, and of various alternative intake technologies identified 

by ENERCON. 

Biological effectiveness has two key aspects. The first aspect of biological 

effectiveness is the degree to which a technology can be expected to reduce the number 

of eggs, larvae, and older life stages of fish lost due to entrainment and impingement 

(“I&E losses”). The second aspect is the degree to which reductions in entrainment and 

impingement losses can be expected to result in measurable increases in the abundance of 

potentially affected fish populations. 

 

1

 The Interim Decision provides that the Department must evaluate Entergy’s alternative technology 

assessment and “[i]f it determines that the proposed alternative may be substituted for closed cycle cooling 

. . . commence a proceeding to modify the permit accordingly.” Id. at 25. 
ii

In this report, reductions in I&E losses were evaluated using a combination of 

laboratory studies, field studies, and theoretical models that address the potential fate of 

fish exposed to cooling water intake structures. This evaluation found that two 

technologies may potentially provide reductions comparable to the reduction achievable 

through closed cycle cooling. These technologies, cylindrical wedgewire screens and 

aquatic filter barriers, have operating characteristics that enhance the ability of small fish, 

including larvae, to avoid contact with the intake structure, thereby preventing injury. 

In addition, a cumulative benefits analysis was performed to determine the 

reductions in I&E losses associated with cylindrical wedgewire screens versus the 

NYSDEC Proposed Project over the projected operating lifetimes of Units 2 and 3. 

ENERCON2

 determined that construction and operation of two large counter-flow, 

forced draft, plume abated hybrid cooling towers to be located on the eastern shoreline of 

the Hudson River at the IPEC site in Westchester County, New York, as proposed 

NYSDEC would not be complete until 2029 due to the technical complexity of the 

project, to permitting requirements, and to likely litigation relating to local zoning 

ordinances. Cylindrical wedgewire screens, by contrast, are a proven technology that 

could be installed at both Unit 2 and Unit 3 by 2013 and 2015, respectively. Immediate 

installation of cylindrical wedgewire screens would result in cumulative reductions in 

I&E losses over the remaining lifetimes of Unit 2 and Unit 3 that are more than two times 

greater than those associated with the NYSDEC Proposed Project. 

The second aspect of biological effectiveness was evaluated using analyses of 

data on fish populations of the Hudson River collected during more than 30 years of 

operation of Indian Point Units 2 and 3. This evaluation indicates that none of the 

technologies evaluated, including the NYSDEC Proposed Project, is likely to measurably 

increase the abundance of any Hudson River fish population as compared to the existing 

technology.

 

2

 Engineering Feasibility and Costs of Conversion of Indian Point Units 2 and 3 to a Closed-Loop 

Condenser Cooling Water Configuration, Enercon Services, Inc., 2010. 
iii

Table of Contents 

 

Executive Summary...................................................................................i 

1. Introduction .................................................................................................................... 1

2. Approach to biological evaluation of alternative technologies ..................................... 3

2.1 Technology descriptions .......................................................................................... 3

2.1.1 The existing technology at the Stations ............................................................ 3

2.1.2 Alternative technologies identified in the ENERCON report ........................... 4

2.1.3 Closed-cycle cooling .......................................................................................... 6

2.2 Interactions of fish with cooling water intake systems ............................................ 6

2.3 Fish species and metrics used to evaluate the biological effectiveness of intake 

technologies .................................................................................................................... 9

2.4 Overview of assessment approach ......................................................................... 10

2.4.1 Baseline definition .......................................................................................... 11

2.4.2 Estimation of baseline I&E losses .................................................................. 12

2.4.3 Development of exclusion factors, wedgewire screen avoidance factors, and 

entrainment and impingement survival factors ......................................................... 13

2.4.4 Conversion of entrainment and impingement losses to equivalent age-1 fish 13

2.5 Computer code verification .................................................................................... 14

3. Results of technology evaluations ............................................................................... 15

4. Cumulative benefits of I&E reductions ...................................................................... 31

4.1 Comparison of immediate installation of cylindrical wedgewire screens to delayed 

installation of the NYSDEC Proposed Project ............................................................ 31

4.2 Sensitivity analysis ................................................................................................. 35

5. Potential I&E impacts of IPEC operations on Hudson River fish populations, with and 

without alternative technologies ................................................................................. 37

5.1 Entergy’s AEI report .............................................................................................. 37

5.2 Empirical assessment of expected population-level effects of reductions in 

entrainment losses due to alternative technologies ....................................................... 38

5.2.1 Methods............................................................................................................ 39

5.2.2 Results ............................................................................................................. 40

6. Conclusions ................................................................................................................. 47

7. References ................................................................................................................... 49
iv

List of Tables

Table 1. Definitions of cases evaluated..........................................................18 

Table 2. Entrainment losses, equivalent age 1 losses, mean percent reductions from 

regulatory baseline, and incremental reductions from alternative baseline for 

alternative intake technologies examined for Units 2 and 3........................19 

Table 3. Impingement losses, equivalent age 1 losses, mean percent reductions from 

regulatory baseline, and incremental reductions from the current technology for 

alternative intake technologies examined for Units 2 and 3........................20 

Table 4. Monthly and annual total percent reduction in age 1 equivalent entrainment 

losses of RIS associated with certain alternative intake technologies for Units 2 

and 3. Reduction calculated from regulatory baseline..............................21 

Table 5. Monthly and annual total percent reduction in equivalent age 1 losses of 

impinged RIS Associated with certain alternative intake technologies for Units 

2 and 3. Reduction calculated from regulatory baseline............................22 

Table 6. Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and 

production forgone (kg) due to entrainment and impingement for alternative 

intake technology for Units 2 and 3....................................................23 

Table 7. Cumulative I&E losses, percent reductions in losses, and savings ratios for 

alternative intake technologies at Indian Point Units 2 and 3.......................33 

Table 8. Cumulative I&E losses, percent reductions in losses, and savings ratios for 

alternative intake technologies at Indian Point Units 2 and 3, with post-2013 

reductions discounted at 3% per year..................................................34 

Table 9. Projected annual increases in age-1 equivalents due to eliminating current 

entrainment losses at Units 2 and 3....................................................42 
v

List of Figures 

Figure 1. Potential fates of organisms exposed to a cooling water intake structure.........7

Figure 2. Sensitivity of cumulative percent reduction estimates for cylindrical wedgewire 

screens to alternative length-specific avoidance curves and assumptions 

concerning the survival of impinged larvae and juveniles.........................36 

Figure 3. Observed year-to-year changes in riverwide juvenile abundance of American 

shad in response to observed year-to-year increases in riverwide post yolk-sac 

larval abundance.........................................................................43 

Figure 4. Observed year-to-year changes in riverwide juvenile abundance of river herring 

in response to observed year-to-year increases in riverwide post yolk-sac larval 

abundance.................................................................................44 

Figure 5. Observed year-to-year changes in riverwide juvenile abundance of striped bass 

in response to observed year-to-year increases in riverwide post yolk-sac larval 

abundance.................................................................................45 

Figure 6. Observed year-to-year changes in riverwide juvenile abundance of white perch 

in response to observed year-to-year increases in riverwide post yolk-sac larval 

abundance.................................................................................46 

Figure 7. Percent reductions in age-1 equivalent entrainment and impingement losses 

compared to the regulatory baseline, for technologies evaluated in this 

report.....................................................................................48 
1

1. Introduction 

 This report supports the “Evaluation of Alternative Intake Technologies at Indian 

Point Units 2 & 3” (“ENERCON Report”) prepared in response to the Interim Decision 

of the NYSDEC Assistant Commissioner requiring Entergy to produce a report 

addressing the feasibility of alternative cooling water intake technologies that will 

minimize adverse environmental impact to a level equivalent to that which can be 

achieved by closed cycle cooling, albeit at a lower cost. In this report, we evaluate the 

“biological effectiveness” of the Stations’ existing technology, the NYSDEC Proposed 

Project, and various alternative intake technologies evaluated by ENERCON. 

 

ENERCON investigated the feasibility of installing the following alternative 

intake technologies at the Stations: 

- Upgrade of the existing fish handling and return systems; 

- Modification of the existing Ristroph-type traveling water screens (“Ristroph 

screens”) to incorporate fine mesh screens; 

- Traveling screen technologies other than Ristroph screens, including dual flow 

traveling water screens, angled traveling screens, WIP screens, and MultiDisc®

screens; 

- Passive intake systems, including cylindrical wedgewire screens, perforated pipe 

inlets, and porous dikes/leaky dams; 

- Barrier technologies, including aquatic filter barriers, fish net barriers, behavioral 

barriers, and louver systems; 

- Alternate intake location; 

- Various types of flow reductions, including via the existing dual/variable speed 

pumps, use of recycled wastewater as cooling water, outage timing, and radial 

wells; and 

- Alternative heat rejection and recirculation, including evaporative ponds, spray 

ponds, cooling canals, and in-river heat exchangers. 

These technologies are described in detail in the ENERCON Report. 

Biological effectiveness has two key aspects. The first aspect of biological 

effectiveness is the degree to which a technology can be expected to reduce the number 

of I&E losses, as compared to closed-cycle cooling. The second aspect is the degree to 

which reductions in I&E losses can be expected to result in measurable increases in the 

abundance of potentially affected fish populations. 

We addressed the first aspect of biological effectiveness using a combination of 

laboratory studies, field studies, and theoretical models that address the potential fate of 

fish that encounter the Stations’ existing intake technology, the NYSDEC Proposed 

Project, and various alternative intake technologies identified by ENERCON. To address 

the second aspect of biological effectiveness, we assessed the long-term impacts of the 

operation of the Stations with and without the existing technology, the alternative intake 
2

technologies, and the NYSDEC Proposed Project on representative important species 

(“RIS”)3

 and the Hudson River ecosystem as a whole. This assessment relied on the 

analyses and conclusions provided in Entergy’s Adverse Environmental Impact Report 

(Barnthouse et al. 2008) (“AEI Report”), as supplemented by new analyses performed to 

support the evaluation of the alternative intake technologies. 

Section 2 of this report provides an overview of how Hudson River fish 

populations come into contact with the Stations’ existing intake structure, brief 

descriptions of the alternative intake technologies we evaluated, and an explanation of the 

methods used to perform the technology comparisons to determine which alternative 

intake technologies results in I&E losses comparable to the NYSDEC Proposed Project. 

Section 3 presents the results of the technology comparisons. Section 4 evaluates the 

benefits that could be achieved through immediate installation of cylindrical wedgewire 

screens as compared to construction of the NYSDEC Proposed Project following the 

schedule developed by ENERCON, which concluded that construction would not be 

complete until 2029. Section 5 discusses the long-term impacts of the Stations’ 

operations, with and without modifications to the Stations’ existing intake technologies, 

on Hudson River fish populations. Section 6 summarizes the conclusions from all of the 

above analyses. Detailed documentation of all calculations is provided in Appendices A 

through C. Appendix D provides additional material supporting the evaluation of longterm impacts in Section 4 of this report. 

 

3

 As discussed in further detail in Entergy’s AEI Report, the original National Pollutant Discharge 

Elimination System (“NPDES”) permit hearings for the Stations identified eight fish species as RIS: 

striped bass, white perch, American shad, Atlantic tomcod, spottail shiner, bay anchovy, alewife, and 

blueback herring. These species were selected because of their recreational, commercial, and ecological 

value. 
3

 2. Approach to biological evaluation of alternative 

technologies 

This section describes the technologies evaluated and explains the methods used 

to perform the technology comparisons. For purposes of introduction, Units 2 and 3 each 

have cooling water intake structures (“CWIS”) located on the eastern shore of the 

Hudson River. These CWIS consist of water intake bays and pumps that provide river 

water to cool the steam condensers (see Section 2.2 of the ENERCON Report). 

Traveling screens4

 located within the intake bays prevent debris from entering the pumps 

and condensers. Eggs, larvae, juveniles, and older fish present in the cooling water may 

come into contact with these screens (a process termed “impingement”), or, if small 

enough to fit through openings in the traveling screens, may be drawn through them and 

pass through the condensers with the cooling water (a process termed “entrainment”). As 

discussed in the following section, a variety of cooling water intake technologies are 

available to reduce I&E losses at power plants. 

2.1 Technology descriptions 

This section describes the existing intake technology at Units 2 and 3, which 

includes many features specifically intended for reducing I&E losses. The existing 

traveling screens and fish return system, portions of which were designed by Dr. Ian 

Fletcher, a consultant to the Hudson River Fisherman’s Association (the “HRFA,” now 

Riverkeeper, Inc.) and subjected to a full-scale field test prior to installation, is described 

below. The description of the existing intake technology is followed by descriptions of 

the alternatives evaluated by ENERCON for feasibility, including the NYSDEC 

Proposed Project. 

2.1.1 The existing technology at the Stations 

The Stations’ existing CWIS already include a number of features that reduce 

I&E losses. These features include: 

- Modified Ristroph-type traveling water screens, 

- Fish handling and return systems, 

- Low pressure screenwash systems, 

- Low temperature increase across the condensers and rapid transit through the 

cooling system, 

- Seasonal flow reductions due to dual/variable speed pump operations, and 

- Flow reductions due to maintenance/refueling outages. 

 

4

 These screens are called traveling screens because they are linked to form a vertically-oriented endless 

belt so that they can be rotated and washed to remove trapped debris. See Section 4.1 of the ENERCON 

Report for a detailed description of the traveling screens installed at Units 2 and 3. 
4

The Stations’ modified vertical Ristroph screens were installed in 1990 following 

a collaborative research effort among the former owners of the Stations and Dr. Fletcher, 

a consultant to Riverkeeper’s predecessor (as noted above).5

 The current Ristroph 

screens were specifically designed to gently remove fish from the cooling water flow and 

return them live to the Hudson River. The Stations’ traveling water screens consist of a 

continuous series of wire mesh panels and curved fish handling buckets attached to 

frames and attached to two matched strands of roller chains. These panels and buckets 

are commonly referred to as Ristroph Screens. 

In addition to the Ristroph screens, the fish handling and return systems and low 

pressure screenwash systems were specifically designed to minimize impingement losses. 

The low through-screen and approach velocities (approximately 1 foot per second 

(“fps”)) when all pumps are operating at full flow) increases the likelihood that 

impingeable sizes of fish may escape the intake flow. The screens are rotated 

continuously, and any fish in proximity to the screens are lifted up in fish collection 

troughs that were specially designed to minimize stress on fish. The screenwash system 

further minimizes stress on fish as they are washed out of the buckets and into the fish 

return system. This system was designed to minimize stress on captured fish, following 

extensive field-scale studies conducted under the review of NYSDEC staff and 

Riverkeeper experts. The discharge points for the Unit 2 and Unit 3 fish return pipes 

were selected after conducting dye and fish release studies to find locations that would 

minimize reimpingement. 

 The comparatively low ΔT (temperature increase as water passes through the 

condenser tubes) of about 10°C, and short transit times (average 9.7 min for Unit 2 and 

5.6 min for Unit 3 at full flow) reduce thermal stress and permit significant entrainment 

survival for some species. 

Flow reductions have the potential to reduce both impingement and entrainment 

at Unit 2 and Unit 3.6

 Both units are equipped with dual or variable speed pumps that 

permit intake flows to be reduced during certain seasons (primarily late October until 

early May). In addition, maintenance outages are scheduled, when reasonably practical, 

during seasons when entrainable life stages, i.e. eggs and larvae, are present in the river. 

Typically, these outages occur during the late spring entrainment period, with the result 

that only one unit is operating during the approximately 25-day outage period each year. 

2.1.2 Alternative technologies identified in the ENERCON report 

In addition to the existing technology, ENERCON evaluated a wide variety of 

alternative intake technologies that could potentially further reduce I&E losses in order to 

determine the feasibility of installing such technologies at the Stations. ENERCON’s 

 

5 Flow Dynamics and Fish Recovery Experiments: Water Intake Systems, Transactions of the American 

Fisheries Society, Vol. 119, No. 3, pp. 393-415 (R. Ian Fletcher). 6

 At a given level of generation, reducing the cooling water flow increases the ΔT and transit time, 

potentially increasing the mortality rate of entrained organisms. To accurately evaluate the benefit of flow 

reductions, the reduced number entrained must be weighed against the potentially higher mortality rate. 
5

evaluations emphasized technologies capable of reducing entrainment, because as 

discussed in Section 4.1 of the ENERCON report, the existing “fish return systems at 

Units 2 and 3 are considered to be state-of-the-art” and that “upgrades to the current fish 

return systems are not expected to provide appreciable biological benefits.” The 

principal technologies evaluated include modification of the existing Ristroph screens to 

incorporate fine mesh screens (Section 4.2.1 of the ENERCON report), cylindrical 

wedgewire screens (Section 4.3.1 of the ENERCON report), aquatic filter barrier systems 

(Section 4.4.1 of the ENERCON report), and operational changes such as flow reductions 

and changes in the timing of maintenance/refueling outages (Section 4.6 of the 

ENERCON report). Technologies that would provide little or no direct reductions in 

entrainment losses (i.e., upgrades to the existing fish handling and return systems, fish 

barrier nets, behavioral barriers, louver systems, additional flow reductions, etc.) were not 

considered as viable alternatives to the current screening systems at the Stations. 

As discussed in Section 4.2.1 of ENERCON’s report, the fine mesh screen 

alternative involves replacing the current 1⁄4” x 1⁄2” mesh screen panels used in the 

Stations’ existing Ristroph screens with panels with smaller mesh sizes are intended to 

screen out fish, small juveniles, larvae, and eggs that pass through the existing screens, 

and thereby reduce entrainment. The eggs, larvae, and early juveniles excluded by the 

fine mesh screen panels would be washed off the screens into the Stations’ fish return 

systems and returned to the River. Entrainment would be reduced because these 

organisms would be impinged rather than entrained. Fish eggs are very fragile and it is 

therefore assumed here that eggs impinged on fine-mesh screens would be unlikely to 

survive. Since it is also assumed that entrained eggs do not survive, fine mesh screens 

would provide no net benefit with respect to eggs. However, larvae and small juvenile 

fish may survive impingement. If the survival rates of larvae and small juveniles is 

higher than the survival rate of entrained larvae and juveniles, then fine mesh screens 

could reduce I&E losses for these life stages. Species-specific entrainment survival 

estimates are discussed in Appendix A to this report; survival estimates for larvae and 

juveniles impinged on fine mesh screens are discussed in Appendix B. 

We evaluated the reduction in I&E losses associated with fine mesh screens with 

mesh sizes ranging from 1-9 mm in this report. Since no changes would be made to the 

fish buckets, the spray wash system, or the fish return system, the survival of older 

impinged fish was expected to be the same as with the existing technology. Fine mesh 

screens with mesh sizes ranging from 1-9 mm are evaluated in this report. 

As discussed in Section 4.3.1 of ENERCON’s report, cylindrical wedgewire 

screens are designed to reduce I&E losses in two ways. Like the Stations’ existing 

Ristroph screen technology, they prevent aquatic organisms larger than the screen slot 

width from entering the intake and becoming entrained. In addition, because cylindrical 

wedgewire screens are typically deployed directly in the source waterbody rather than 

being housed within an intake bay, flows within the source water body (e.g., the tidal 

flows in the Hudson River) create hydrodynamic forces that can sweep organisms past 

the cylindrical wedgewire screens without coming into physical contact with the screen. 

Thus, even organisms that are smaller in diameter than the screen slot width can be swept 

passed the intake. Because of the very low through-screen current velocity and the 
6

sweeping currents that move organisms past the intake structure, cylindrical wedgewire 

screens are expected to eliminate impingement and greatly reduce entrainment. We 

evaluated the biological effectiveness of wedgewire screens with slot widths from 1-9 

mm in this report. 

As discussed in Section 4.4.1 of ENERCON’s report, aquatic filter barriers 

represent a relatively new fish protection technology. The filter barrier is a fabric curtain, 

completely surrounding the intake structure, which allows water to pass through while 

excluding fish, larvae and eggs. Because of the very low through-screen current velocity 

most organisms, specifically fish of all ages and larvae, should be able to avoid the 

curtain rather than be physically excluded. Thus, this technology is expected to greatly 

reduce or eliminate both entrainment and impingement. The evaluation of aquatic filter 

barriers in this report includes an estimation of the fraction of fish, eggs, and larvae in the 

vicinity of the intake that pass under, over, or through gaps in the barrier and 

subsequently are entrained or impinged. 

As discussed in Section 4.6 of ENERCON’s report, reducing intake flows would 

also reduce I&E losses. Flow reductions result in reductions in the power output of the 

Stations. Several alternative flow and power reduction scenarios were evaluated by 

ENERCON. The analysis of I&E losses includes changes to both the numbers entrained 

or impinged and their mortality rates. In addition, ENERCON evaluated the benefits of 

changing the timing of maintenance/refueling outages to occur during the month for 

which outages would provide the greatest percent reduction in age-1 equivalent 

entrainment losses compared to the existing technology, while avoiding outages during 

peak-demand summer months. 

2.1.3 Closed-cycle cooling 

In the draft SPDES permit NYSDEC issued in 2003, NYSDEC proposed the 

NYSDEC Proposed Project.7

 Pursuant to the Interim Decision, NYSDEC may revisit 

this proposal and change it pursuant to Entergy’s alternative technologies assessment 

2.2 Interactions of fish with cooling water intake systems 

Four life stages of fish are relevant to evaluating cooling water intake 

technologies: eggs, larvae, juvenile fish (also called “young-of-the-year” or “YOY”), and 

older fish. An egg, larva, juvenile, or older fish approaching the Stations has 3 possible 

fates, as illustrated in Figure 1. First, if it is able to swim, it may avoid contact with the 

screen by swimming or moving away. This fate is termed “avoidance.” Second, it may 

come into contact with the screen but be excluded from the intake because it is too large 

to pass through the screen. This fate is termed “impingement.” Impinged fish, larvae, 

and eggs are washed off the screen and returned to the river via the Stations’ fish return 

system. Third, it may pass through the screen, be entrained through the plant, and 

discharged back into the River. This fate is termed “entrainment.” 

 

7

 Discussed in ENERCON’s report entitled “Engineering Feasibility and Costs of Conversion of Indian 

Point Units 2 and 3 to a Closed-Loop Condenser Cooling Water Configuration” 
7

Figure 1 Potential fates of organisms exposed to a cooling water intake structure. 

Only organisms in the shaded compartments in Figure 1 are included in the loss 

estimates.

Organisms 

approaching CWIS

Avoidance

Exclusion

Avoid-live

Impinged-live

Impinged-dead

Entrained-live

Entrained-dead

Survive?

Survive?

No contact with

screen

Pass through

screen

Yes

Yes

No

No

Fate

Entrainment

Excluded

By screen

Organisms 

approaching CWIS

Avoidance

Exclusion

Avoid-live

Impinged-live

Impinged-dead

Entrained-live

Entrained-dead

Survive?

Survive?

No contact with

screen

Pass through

screen

Yes

Yes

No

No

Fate

Entrainment

Excluded

By screen
8

The relative probability of each of these events events set out in Figure 1 occurring 

differs on the life stage of the fish and the type of technology installed. With respect to 

avoidance, fish eggs have no swimming ability, so they cannot avoid the intake. 

Depending on the dimensions of the screen mesh, they may be excluded. If they are 

small enough to pass through the mesh, they are entrained. Larvae have a weak 

swimming ability that increases as they grow. Some technologies, and in particular 

cylindrical wedgewire screen technology, take advantage of “sweeping” currents in the 

source water body to move organisms past the intake structure without being excluded or 

entrained. Experimental studies appear to show that larvae can detect the currents 

drawing water through the screen, move away, be drawn into the sweeping current, and 

avoid impingement and entrainment (see discussion in Appendix B). These same studies 

have shown that the avoidance ability of larvae is a function of length, i.e., larger larvae 

have much more avoidance ability than smaller larvae. It is generally accepted that, for 

any screening technology, if intake flow velocities are at or below 0.5 fps, juvenile and 

older fish can avoid impingement. Fish that do not avoid the intake structure are either 

impinged or entrained. Juvenile and older fish large enough to be excluded with the 

Stations’ existing technology will also be excluded by all of the other technologies 

evaluated in this report. 

Entrainment – the third possible fate of an organism approaching an intake – occurs when 

eggs, larvae, and very small juvenile fish pass through the mesh in the Stations’ existing 

technology. Traveling screens with finer mesh sizes – one of the alternatives discussed in 

Section 2.1.2 above – will exclude some of these fish, so that they are impinged rather 

than entrained. The avoidance factors and exclusion factors used in this report are 

documented in Appendix B. Survival rates of fish impinged with the existing technology 

are discussed in Appendix A. 

The probability that an egg, larva, juvenile, or older fish will survive its encounter 

with the Stations depends on its age and size and whether it avoids the intake, or is 

entrained or impinged. For this assessment, because fish eggs are very fragile it is 

assumed that all eggs that encounter the intake structure do not survive. This is a 

conservative assumption that is made because no species-specific estimates of 

impingement or entrainment survival of eggs are available. However, species-specific 

survival studies performed at the Stations have shown that larvae and small juveniles may 

survive entrainment. Many studies of entrainment and impingement survival at Units 2 

and 3 have been performed. Results of these studies have recently been summarized by 

Young et al. (2009) for striped bass. Site-specific entrainment survival values for all RIS 

species are documented in Appendix A. Larvae, juveniles, and older fish may survive 

impingement and subsequently return to the river, with the probability of survival 

depending on the species and size of the fish. Estimates of impingement survival for 

small fish impinged on fine mesh screens are documented in Attachment B. Larvae, 

juveniles, and older fish are assumed to survive if they successfully avoid contact with 

the intake (Appendix B). 
9

2.3 Fish species and metrics used to evaluate the biological 

effectiveness of intake technologies 

Eight species commonly entrained or impinged at Unit 2 and Unit 3 are addressed 

in this report: striped bass, white perch, American shad, Atlantic tomcod, spottail shiner, 

bay anchovy, and two species collectively known as “river herring” (alewife and 

blueback herring). These species were identified by NYSDEC as RIS for the original 

NPDES permit hearings for the Stations. In addition to being considered important due 

to their recreational, commercial, and ecological value, these species have historically 

accounted for more than 98% of fish larvae and 92% and of juvenile fish (YOY) fish 

captured, respectively, in the utilities’ LRS and Beach Survey (CHGE 1999, Tables V-45 

and V-46). A detailed discussion of the biological attributes of each RIS species is 

provided in the Section V of Draft Environmental Impact Statement (“DEIS”) prepared 

by the Hudson River utility companies (CHGE 1999). 

 

As discussed in Entergy’s AEI Report (Barnthouse et al. 2008), natural mortality 

of early life stages of fish is very high. For example, according to Secor and Houde 

(1995), more than 99.99% of newly-spawned striped bass eggs die from natural causes 

within 60 days. Only about one striped bass egg in 100,000 is likely to survive to 

become a one-year-old fish. As young fish develop and grow, mortality rates decline. 

According to Secor and Houde (1995), 97% of the youngest and smallest striped bass 

larvae can be expected to die each day. Of those that survive to reach the next stage of 

development, approximately 15% can be expected to die each day until they transform 

into juvenile fish. Approximately 4% of striped bass that survive until the juvenile stage 

would be expected to survive to become one-year-old fish. Because their probabilities of 

survival are so low, fish eggs and larvae make much smaller contributions to the adult 

populations of fish than do juvenile and older fish. For this reason, the total number of 

eggs, larvae, juvenile, and older fish entrained or impinged provides an inaccurate and 

potentially misleading metric for evaluating the benefits of alternative intake 

technologies. 

EPA recognized this problem in performing its case study reports supporting the 

Phase II rulemaking (EPA 2002, 2004). Rather than basing the case studies on total 

numbers of fish entrained or impinged, EPA converted the numbers of fish entrained or 

impinged at different ages to equivalent one-year-old fish using estimates of the 

probabilities that fish entrained or impinged at various ages would survive to age 1. 

Conversion to equivalent age-1 fish allows I&E losses that occur at different life stages to 

be combined into a single metric that weights the losses according to the number that 

could, on average, have survived to age 1. The biological effectiveness of each 

alternative, using this approach, reflects the net effectiveness of that alternative at 

reducing losses of young fish, including both entrainment and impingement losses. More 

detailed discussions of the conversion methodology can be found in the EPA case study 

reports (EPA 2002, 2004) and in guidance manuals prepared for the Electric Power 

Research Institute (EPRI 2004, 2005). 
10

2.4 Overview of assessment approach 

The approach used to evaluate the biological effectiveness of alternative intake 

technologies, as compared to closed-cycle cooling, involves the following steps: 

- Definition of baseline impingement and entrainment losses, 

- estimation of the reduction in impingement and entrainment losses, expressed as 

equivalent age-1 fish, that could be achieved using each technology alternative, 

and 

- comparison of all alternatives to closed-cycle cooling. 

As discussed below, two different conceptual definitions of baseline losses are 

used in this report: a “regulatory baseline” that has recently been used by NYSDEC in 

SPDES permit proceedings for other New York power plants, and an “alternative 

baseline” intended to more closely approximate actual impingement and entrainment 

losses that would occur at Unit 2 and Unit 3, if the existing intake technology had not 

been installed. For both definitions, estimation of baseline impingement and entrainment 

losses requires the use of historical data to estimate impingement and entrainment losses 

under current conditions. Data from laboratory experiments, field tests, and full-scale 

operation of the alternatives are then used to estimate the reductions in impingement and 

entrainment at Unit 2 and Unit 3 that would be expected, if these technologies were 

deployed. 

This section summarizes all of the above procedures. In addition, it summarizes 

the steps performed to ensure that the computer programs used to process the data and 

perform the calculations were free from errors that could compromise the validity of the 

assessment. Detailed documentation of all of these procedures is provided in Appendices 

A and B. 
11

2.4.1 Baseline definition 

 

In recent regulatory practice under 6 NYCRR 704.5 (the New York statutory 

equivalent of §316(b) of the Clean Water Act), NYSDEC has evaluated the effectiveness 

of proposed intake technologies at reducing I&E losses by comparing the estimated I&E 

losses for the proposed technology to the losses that would occur under a “baseline” 

condition. The baseline losses are those that would occur if the station were built and 

operated according to the following conditions: 

- Shoreline intake structure withdrawing from surface waters, 

- 3/8” mesh traveling screens operated as needed for debris removal, 

- Full flow operation 365 days per year, and 

- No survival of impinged or entrained fish 

 This baseline is a regulatory construct that assumes that no entrained or impinged 

fish survive, regardless of the effectiveness of existing technologies. In reality, field 

studies conducted at the Stations have demonstrated that for some species the survival of 

entrained organisms is high, even in the absence of technologies specifically employed to 

reduce entrainment mortality (See Appendix A).8

 Hence, the regulatory baseline is not 

intended to and does not describe historical I&E losses at Unit 2 and Unit 3. The failure 

of the regulatory baseline to consider entrainment survival does not affect the technology 

evaluations presented in this report, because the percent reductions in entrainment losses 

for the alternative technologies (which include site-specific estimates of entrainment and 

impingement survival) are compared to percent reductions associated with closed-cycle 

cooling, relative to the same baseline. 

The failure of the baseline to consider entrainment survival would, however, be 

important if the economic benefits of the alternatives were being evaluated. An 

economic benefits analysis is different from regulatory analysis focused on determining 

compliance with a performance standard. An economic benefits analysis involves 

assigning monetary values to the numbers of fish saved by each technology. For species 

such as striped bass, which have shown relatively high rates of entrainment survival in 

site-specific studies, the use of the regulatory baseline would substantially bias benefits 

estimates because much of the calculated reduction in entrainment losses would reflect 

the zero survival assumption used in the baseline, not the actual performance of the 

technologies. 

For this reason, an alternative baseline was developed using the configuration and 

flow assumptions used in the regulatory baseline, but using site-specific estimates of the 

entrainment survival that would be expected to occur under those assumptions. This 

baseline is still conservative because it assumes that both Unit 2 and Unit 3 operate at full 

flow for 365 days per year, with no maintenance outages. Incremental reductions in 

 

8

 This inconsistency does not affect comparative estimates of impingement losses, because Unit 2 and Unit 

3 were originally built without fish return systems, so that survival of impinged fish would have been zero, 

as assumed in the regulatory baseline. 
12

losses for the existing technology are compared to the alternative baseline, and 

incremental reductions for all other technologies were compared to the existing 

technology. In addition, the alternative baseline is used to calculate the fishery yield and 

foregone fish production (i.e., biomass of prey fish such as bay anchovy available for 

consumption by predators such as striped bass) represented by these fish. The methods 

used for these calculations are the same methods used in the EPA regional case studies 

(EPA 2002, 2004) and recommended in EPRI guidance (EPRI 2004). 

2.4.2 Estimation of baseline I&E losses 

The most recent information on species-specific entrainment densities (number of 

organisms per volume of water withdrawn) at Units 2 and 3 are for the years 1983-1987. 

As discussed in Entergy’s AEI Report, the relative abundances of the eight RIS present in 

the river have changed since the 1980s, and these changes in abundance likely would 

have also changed the numbers of each species entrained at Unit 2 and Unit 3. To 

estimate levels of entrainment that would have been expected in more recent years, 

estimates of the numbers of each species in the vicinity of IPEC during the years 1983-

1987, as measured in the LRS, were compared to estimates of the density of that species 

in entrainment samples. These comparisons were used to calculate “conversion factors” 

that relate the abundance of each species in the river to its density in entrainment 

samples. These conversion factors were then applied to river abundance estimates for the 

years 2001-2007 to produce estimates of the density of each species that would have been 

expected in entrainment samples during those years. The years 2001-2007 are the most 

recent years for which data from the LRS are available, therefore, they provide the best 

available information concerning the abundance of RIS species currently present in the 

vicinity of Unit 2 and Unit 3. Because probabilities of exclusion, avoidance, and 

survival of potentially entrained larvae differ depending on length (see section 2.2 

above), length distribution data for larvae entrained during 1983-1987 were used to 

estimate the length distributions of larvae that would have been entrained during 2001-

2007. Appendix A provides a detailed explanation of the procedures used to perform all 

of the above calculations. 

A similar procedure was used to estimate expected impingement of each RIS for 

the years 2001-2007. Impingement sampling at IPEC was conducted from 1972 through 

1990. The most recent seven years of impingement sampling (1984-1990) were selected 

for use in estimating recent impingement rates, because a consistent, statistically-based 

sampling design was used to estimate impingement during these years (Mattson et al. 

1988). Because impingement data were collected and analyzed in exactly the same way 

during each of these years, we can be confident that the results are not biased due to 

changes in sampling design. Quarterly impingement densities, by species, for each year 

during this period were related to the abundance of each species in the river during that 

month, as estimated from Beach Seine Survey (“BSS”) and Fall Shoals Survey (“FSS”) 

data. These two programs sampled fish within the size range that are impinged at Unit 2 

and Unit 3. Conversion factors analogous to those developed for entrainment were 

applied to river abundance data for 2001-2007 to obtain monthly estimates of 
13

impingement, by species for these years. Appendix A provides a detailed explanation of 

the procedures used to perform all of the above calculations. 

Operational measures (flow reductions and outages) and the NYSDEC Proposed 

Project reduce the number of organisms subject to impingement and entrainment by 

reducing the volume of water withdrawn from the Hudson River for condenser cooling. 

Entrainment and impingement estimates for these technologies were obtained by 

reducing the entrainment and impingement estimates proportionate to the estimated 

reductions in intake flows. 

2.4.3 Development of exclusion factors, wedgewire screen avoidance 

factors, and entrainment and impingement survival factors 

Most of the technology alternatives evaluated in this report reduce I&E losses by 

increasing the exclusion of eggs, larvae, and small juveniles from the intake structure, by 

permitting some larvae and juveniles to avoid physical contact with the intake structure, 

or by increasing the survival rate of fish that encounter the intake structure. Estimates of 

species and length-specific exclusion, avoidance, and survival factors are needed to 

quantify the biological benefits of these alternatives. Estimates of species-specific and 

size-specific exclusion and avoidance factors were developed for each RIS and are 

documented in Appendix B. These factors permit length-specific evaluations of the 

effect of wedgewire screen slot width on the fraction of fish larvae and small juveniles 

that avoid contact with the intake structure. They also permit size and species-specific 

evaluation of the effect of wedgewire screen slot width and fine mesh screen mesh size 

on the fraction of fish larvae and small juveniles that are impinged versus entrained. 

Estimates of impingement survival rates for very small fish impinged on fine 

mesh screens are documented in Appendix B. Estimates of entrainment survival rates 

and impingement survival for fish impinged on the existing intake technology, 

specifically the Ristroph screens at Unit 2 and Unit 3 are documented in Appendix A. In 

the case of entrainment, survival rates for flow reduction scenarios were adjusted, where 

necessary, to account for the effects of increased discharge temperatures on survival rates 

of entrained larvae (i.e., when flow is reduced, the discharge temperature increases, 

which results in less survival). 

2.4.4 Conversion of entrainment and impingement losses to 

equivalent age-1 fish 

As discussed in Section 2.3 above, conversion of I&E losses to age-1 equivalents 

allows I&E losses that occur at different life stages to be combined into a single metric 

that weights the losses according to the number that could, on average, have survived to 

age 1. After adjusting the entrainment estimates to account for avoidance and survival, 

life-stage-specific estimates of entrainment losses for each species were converted to 

equivalent age-1 fish and then summed. Larvae that would have been entrained using the 

Stations’ current intake technology but would instead be impinged on modified Ristroph 

screens (i.e., fine mesh screens) are included in the entrainment totals, but with the 
14

survival factors for impingement rather than entrainment applied. Similarly, after 

adjustments for avoidance and survival, estimates of impingement losses for each species 

were converted to equivalent age-1 fish. The parameter values used for these calculations 

are documented in Appendix A. 

2.5 Computer code verification 

Hudson River data sets, collected over more than 35 years by multiple 

contractors, constitute the most comprehensive data set available for any estuarine fish 

community in North America. However, because sampling protocols and data recording 

methods have changed with time, these data sets are very complex, and the computer 

programs (termed “codes” by program writers) needed to access these data and convert 

them to a form that can be used to implement the models used in this report are similarly 

very complex. The codes used here for this purpose are all written in the SAS 

programming language. To verify that SAS codes used in this evaluation are accurate, 

one of the contractors (Normandeau Associates) performed an independent verification of 

the codes developed by another contractor (ASA). The steps involved in the verification 

process are documented in Appendix B. 
15

 3. Results of technology evaluations 

Table 1 summarizes the “cases” included in the alternatives analysis. Cases 0 and 

0.5 represent, respectively, the regulatory baseline and the alternative baseline used in the 

calculations. Case 1 represents the existing intake technology at the Units 2 and 3, 

including the fish return system and the Ristroph screens. Cases 1.001 through 1.204 

represent the existing intake technology, supplemented with several combinations of flow 

reductions and power reductions. Case 1.5 represents a one-month, one-unit outage 

scheduled during the month (September) that would provided the greatest estimated 

reduction in total age-1 equivalent entrainment losses compared to the existing 

technology, while avoiding outages during high-demand summer months (Enercon, 

Section 4.6). Cases 2 through 7 represent cylindrical wedgewire screens with slot widths 

ranging from 1 mm to 9 mm. Cases 8 through 13 represent fine mesh screens with mesh 

sizes ranging from 1-9 mm. Case 14 represents the aquatic filter barrier, and cases 15 

and 15.5 represent closed-cycle cooling scenarios using alternative assumptions about the 

magnitude of service water flows used for make-up water. 

Tables 2 and 3 summarize, respectively, entrainment and impingement outputs for 

each case, including annual mean total losses over all species, annual mean total age-1 

equivalent losses over all species, mean percent reductions in losses and age-1 equivalent 

losses compared to the regulatory baseline, and incremental reductions compared to the 

alternative baseline (for the existing technology) or compared to the existing technology 

(all other technologies). To calculate the mean percent reductions, percent reductions in 

losses were calculated for each RIS, for each year from 2001-2007. These annual values 

were averaged across all species, and then the yearly across-species averages were 

averaged to obtain a mean percent reduction over all years. The reason for averaging 

across species is that a truer measure of technology effectiveness for all of the RIS can be 

obtained. If percent reductions were to be calculated on the total losses, then the 

effectiveness measures would be dominated by the most abundant taxa, bay anchovy, and 

to a lesser extent striped bass. Averaging percent reductions across species provides a 

better discrimination between technologies because it gives equal weight to species such 

as Atlantic tomcod and white perch, which would receive little weight if metrics were 

based on abundance. 

Table 4 provides estimates of the percent reduction in equivalent age-1 losses due 

to entrainment, by month, as calculated using the regulatory baseline. These values 

quantify the contribution of each month to the total percent reduction in age-1 equivalent 

losses. Apportioning the total percent reduction by month permits evaluation of seasonal 

variations in effectiveness. For example, technologies such as wedgewire screens and 

filter barriers that reduce entrainment provide nearly all their benefits between May and 

October, because these are the months in which entrainable life stages are most abundant 

in the river. If, for operational reasons, it proved to be impractical to deploy these 

technologies during the winter, there would be little or no reduction in the effectiveness 

of these technologies with respect to entrainment. Table 5 provides similar estimates of 

monthly percent reductions for impingement. 
16

Table 6 provides estimates of total age-1 equivalent losses, equivalent yield to 

fisheries, and production foregone for each technology alternative for each RIS. These 

estimates are for entrainment and impingement combined. Equivalent yield, as discussed 

by EPRI (2004) refers to the reduction in harvest of recreationally or commercially 

important species due to entrainment and impingement. Production foregone, as 

discussed by EPRI (2004), refers to the reduction in prey biomass available to predators 

due to entrainment and impingement of prey species. These values are not used in the 

technology comparisons, but would be used in economic benefits analyses such as those 

performed in EPA’s case studies (EPA 2002, 2004). 

Table 2 shows that, compared to the regulatory baseline, all of the technologies, 

including the current technology, provide a 30% or greater reduction in age-1 equivalent 

losses, as compared to the regulatory baseline. However, wedgewire screens and aquatic 

filter barriers provide reductions in age-1 equivalent losses of approximately 90%, only 

slightly lower than the reduction calculated for the NYSDEC Proposed Project (96.3% to 

97.6%). Flow reductions, combined with various levels of reduction in power output, 

provide reductions in age-1 equivalent losses between 35% and 50%. Shutdown of one 

unit during September of each year reduces age-1 equivalent losses by 36.3% compared 

to the regulatory baseline. Table 2 also shows that the estimated incremental reduction in 

losses (comparisons to the alternative baseline or current technology) is negative for 

some fine mesh alternatives. A negative value for the incremental reduction indicates the 

estimated losses for the alternative technology are greater than the estimated losses for 

the current technology. 

Modification of the existing Ristroph screens to incorporate fine-mesh screens, 

regardless of mesh size, provides no additional benefits over the Stations’ current 

technology and, depending on the assumptions made concerning the survival of fish that 

are impinged rather than entrained, may actually be more harmful than the current 

technology. The reason for this result is that, for some species and length classes, 

entrainment survival rates are higher than corresponding impingement survival rates (See 

section 2.1.2 above). 

Results of this evaluation indicate that cylindrical wedgewire screens and aquatic filter 

barriers are nearly as effective as closed-cycle cooling at reducing entrainment mortality. 

The reason for the effectiveness of these technologies is that larvae have a high 

probability of avoiding direct contact with the screen. In the case of wedgewire screens, 

as discussed in Appendix B, the sweeping flow of the Hudson River appears to act 

together with the limited avoidance abilities of fish larvae to allow larvae to be diverted 

around the screen rather than being impinged on the screen or passing through the screen. 

Eggs and very small larvae are unable to avoid the screen, but high percentages of larger 

larvae appear to avoid entrainment and impingement (see Section 2.2 above). Available 

data indicate that the avoidance phenomenon is only slightly affected by slot width. 

Aquatic filter barriers also appear to be highly effective at reducing entrainment of 

species and sizes of eggs and larvae. The pore dimensions of these barriers are small 

enough to exclude all life stages of fish, and the through-barrier velocity is low enough to 
17

prevent impingement. However, aquatic filter barriers deployed at the Lovett Generating 

Station (discussed in Attachment B) have at best about 90% effective, because under 

some conditions unfiltered water can pass over the barrier, under the barrier, or through 

gaps or holes in the barrier. 

Table 3 shows that, regardless of which baseline is used, the existing intake 

technology provides approximately an 80% reduction in impingement mortality. Flow 

reductions and modified outage schedules provide incremental reductions in 

impingement losses due to reduced intake flows. Modification of the existing Ristroph 

screens to incorporate fine mesh screens, regardless of mesh size, provide no additional 

protection. Cylindrical wedgewire screens and aquatic filter barriers provide reductions 

in age-1 equivalent losses due to impingement that are equal to or greater than the 

reduction provided by closed-cycle cooling. In the case of wedgewire screens, the 

cylindrical design, the low intake velocity, and the sweeping flow permit actively 

swimming fish to avoid contact with the screen and move with the sweeping flow. In the 

case of aquatic filter barriers, the through-barrier velocity is too low to trap fish. 

Table 4 shows that, for all technologies, most of the reductions in entrainment 

mortality compared to the regulatory baseline occurs in June, July and August. These are 

the months in which entrainable life stages are most abundant, because spawning of all 

RIS species except Atlantic tomcod occurs during the spring and summer. In contrast, 

Table 5 shows that reductions in impingement mortality are spread much more evenly 

throughout the year, with the highest values occurring in January, February, and March. 

The reason for this is that impingeable sizes of white perch and, to a lesser extent, striped 

bass, are abundant in the vicinity of Unit 2 and Unit 3 during the winter. 

Table 6 shows that, for all species and technologies, entrainment accounts for 

most of the losses of equivalent age-1 fish, equivalent yield, and production foregone. 

Bay anchovy accounts for most of the equivalent age-1 fish and production foregone lost 

due to entrainment and impingement and striped bass accounts for most of the foregone 

equivalent yield to fisheries. Cylindrical wedgewire screens and aquatic filter barriers 

provide biological effectiveness benefits – as measured in reductions in impingement and 

entrainment losses – that are comparable to those provided by the NYSDEC Proposed 

Project. 
18

Table 1. Definitions of cases evaluated 

Case no. Technology Source 

0 Regulatory baseline This report, section 2.2.1 

0.5 Alternative baseline This report, section 2.2.1 

1 Existing intake technology9 ENERCON report, section 3 

1.001 Flow reduction, 0 MW loss ENERCON report, section 4.6.1 

1.101 Flow reduction, 10 MW loss ENERCON report, section 4.6.1 

1.202 Flow reduction, 20 MW loss ENERCON report, section 4.6.1 

1.203 Flow reduction, 20-30 MW loss ENERCON report, section 4.6.1 

1.204 Flow reduction, 20-40 MW loss ENERCON report, section 4.6.1 

1.5 One-unit maintenance outage in September each 

year 

ENERCON report, section 4.6.3 

2 1-mm cylindrical wedgewire screen ENERCON report, section 4.3.1 

3 1.5-mm cylindrical wedgewire screen ENERCON report, section 4.3.1 

4 2-mm cylindrical wedgewire screen ENERCON report, section 4.3.1 

5 3-mm cylindrical wedgewire screen ENERCON report, section 4.3.1 

6 6-mm cylindrical wedgewire screen ENERCON report, section 4.3.1 

7 9-mm cylindrical wedgewire screen ENERCON report, section 4.3.1 

8 1-mm mesh alternative Ristroph screen ENERCON report, section 4.2.1 

9 1.5 mm mesh alternative Ristroph screen ENERCON report, section 4.2.1 

10 2-mm mesh alternative Ristroph screen ENERCON report, section 4.2.1 

11 3-mm mesh alternative Ristroph screen ENERCON report, section 4.2.1 

12 6-mm mesh alternative Ristroph screen ENERCON report, section 4.2.1 

13 9-mm mesh alternative Ristroph screen ENERCON report, section 4.2.1 

14 Aquatic filter barrier ENERCON report, section 4.4.1 

15 NYSDEC Proposed Project min SW (Closed-cycle 

cooling with minimum service water use) 

ENERCON cooling tower report10

15.5 NYSDEC Proposed Project max SW (Closedcycle cooling with maximum service water use) ENERCON cooling tower report 

 

9

 Ristroph screens with 6 mm x 12 mm mesh panels, as described in Section 4.1 of the ENERCON 

alternatives report. 

10 “Engineering Feasibility and Costs of Conversion of Indian Point Units 2 and 3 to a Closed-Loop 

Condenser Cooling Water Configuration” 
19

Table 2. Entrainment losses, equivalent age 1 losses, mean percent reductions from 

regulatory baseline, and incremental reductions from alternative baseline for alternative 

intake technologies examined for Units 2 and 3. 

Case Alternative 

Losses Equivalent age 1 

Mean 

(millions) 

% 

reduction 

from 

regulatory 

baseline 

Incremental 

reduction11

Mean 

(millions) 

% 

reduction 

from 

regulatory 

baseline 

Incremental 

reduction

0 Regulatory Baseline 1,224 0.0 3.270 0.0 

0.5 Alternative Baseline 687 23.7 0 2.834 17.2 0.000 

1 Existing intake technology 646 34.7 42 2.637 33.8 0.197 

1.001 Flow Reduction 0MW Loss 632 35.9 14 2.597 35.7 0.040 

1.101 Flow Reduction 10MW 

Loss 

587 45.1 58 2.174 44.7 0.462 

1.202 Flow Reduction 20MW 

Loss 

578 47.4 68 1.997 47.8 0.640 

1.203 Flow Reduction 20-30MW 

Loss 

567 48.6 78 1.895 49.6 0.742 

1.204 Flow Reduction 20-40MW 

Loss 

565 48.8 80 1.881 49.9 0.756 

1.5 September maintenance 

outage 

631 35.5 15 2.610 36.3 0.198 

2 1-mm wedgewire screen 316 79.0 329 0.301 88.8 2.335 

3 1.5-mm wedgewire screen 268 80.2 378 0.278 89.7 2.359 

4 2-mm wedgewire screen 262 80.3 384 0.275 89.8 2.362 

5 3-mm wedgewire screen 262 80.2 383 0.277 89.7 2.360 

6 6-mm wedgewire screen 262 80.2 383 0.279 89.6 2.358 

7 9-mm wedgewire screen 262 80.2 383 0.279 89.6 2.358 

8 1-mm mesh alternative 

Ristroph screen 

898 25.2 -252 2.656 28.0 -0.019 

9 1.5mmmesh alternative 

Ristroph screen 

731 30.2 -85 2.562 31.5 0.075 

10 2-mm mesh alternative 

Ristroph screen 

672 33.1 -26 2.520 33.5 0.117 

11 3-mm mesh alternative 

Ristroph screen 

646 35.0 0 2.499 34.9 0.138 

12 6-mm mesh alternative 

Ristroph screen 

646 34.7 0 2.637 33.8 0.000 

13 9-mm mesh alternative 

Ristroph screen 

647 33.0 -1 2.690 31.5 -0.053 

14 Aquatic Filter Barrier 134 88.0 511 0.474 90.4 2.162 

15 NYSDEC Proposed Project 

min SW 

35 97.4 611 0.095 97.6 2.542 

15.5 NYSDEC Proposed Project 

max SW 

54 96.0 591 0.141 96.3 2.495

 

11 For the current technology (case 1) the incremental reduction is the reduction compared to the alternative 

baseline. For all other technologies, the incremental reduction is the reduction compared to the current 

technology. 
20

Table 3. Impingement losses, equivalent age 1 losses, mean percent reductions from 

regulatory baseline, and incremental reductions from the current technology for 

alternative intake technologies examined for Units 2 and 3. 

Case Alternative 

Losses Equivalent Age 1 

Mean 

% 

reduction 

from 

regulatory 

baseline

Incremental 

reduction12

Mean 

% 

reduction 

from 

regulatory 

baseline

Incremental 

reduction 

0 Baseline 669,465 0.0 484,294 0.0 

1 Existing technology 70,415 79.9 0 49,926 80.2 0 

1.001 Flow Reduction 0 MW Loss 66,914 80.8 3,501 47,703 80.8 2,223 

1.101 Flow Reduction 10 MW Loss 61,518 83.6 8,897 43,760 83.9 6,166 

1.202 Flow Reduction 20 MW Loss 60,843 84.2 9,572 43,081 84.7 6,846 

1.203 Flow Reduction 20-30 MW 

Loss 

60,619 84.5 9,795 42,776 85.0 7,149 

1.204 Flow Reduction 20-40 MW 

Loss 

60,598 84.5 9,817 46,077 85.1 7,181 

1.5 September maintenance outage 69,859 80.8 555 49,118 81.3 809 

2 1-mm wedgewire screen 2,598 99.3 67,816 1,824 99.4 48,102 

3 1.5-mm wedgewire screen 2,598 99.3 67,816 1,824 99.4 48,102 

4 2-mm wedgewire screen 2,598 99.3 67,816 1,824 99.4 48,102 

5 3-mm wedgewire screen 2,598 99.3 67,816 1,824 99.4 48,102 

6 6-mm wedgewire screen 2,598 99.3 67,816 1,824 99.4 48,102 

7 9-mm wedgewire screen 2,598 99.3 67,816 1,824 99.4 48,102 

8 1-mm mesh alternative 

Ristroph screen 

70,415 79.9 0 49,926 80.2 0 

9 1.5mmmesh alternative 

Ristroph screen 

70,415 79.9 0 49,926 80.2 0 

10 2-mm mesh alternative 

Ristroph screen 

70,415 79.9 0 49,926 80.2 0 

11 3-mm mesh alternative 

Ristroph screen 

70,415 79.9 0 49,926 80.2 0 

12 6-mm mesh alternative 

Ristroph screen 

70,415 79.9 0 49,926 80.2 0 

13 9-mm mesh alternative 

Ristroph screen 

70,415 79.9 0 49,926 80.2 0 

14 Aquatic Filter Barrier 16,840 95.3 53,575 11,926 95.3 38,000 

15 NYSDEC Proposed Project – 

min SW 

2,817 99.3 67,598 1,979 99.3 47,948 

15.5 NYSDEC Proposed Project – 

Max SW 

4,277 98.9 66,137 3,034 98.9 46,892 

 

12 For the current technology (case 1) the incremental reduction is the reduction compared to the alternative 

baseline. For all other technologies, the incremental reduction is the reduction compared to the current 

technology. 
21

Table 4. Monthly and annual total percent reduction in age 1 equivalent entrainment 

losses of RIS associated with certain alternative intake technologies for Units 2 and 3. 

Reduction calculated from regulatory baseline.

Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

0.5 Alternative Baseline 0.0 0.0 0.0 0.2 4.8 9.0 1.2 0.5 0.7 0.7 0.0 0.0 17.2

1 Existing technology 0.0 0.0 0.0 0.4 6.1 14.3 6.4 4.1 1.3 1.1 0.0 0.0 33.8

1.001 Flow Reduction 

0MW Loss 

0.0 0.0 0.0 0.4 6.3 14.9 7.3 4.2 1.4 1.2 0.0 0.0 35.7

1.101 Flow Reduction 

10MW Loss 

0.0 0.0 0.0 0.4 6.5 17.1 10.2 6.0 2.3 2.1 0.0 0.0 44.7

1.202 Flow Reduction 

20MW Loss 

0.0 0.0 0.0 0.4 6.5 17.2 11.8 7.0 2.7 2.2 0.0 0.0 47.8

1.203 Flow Reduction 20-

30MW Loss 

0.0 0.0 0.0 0.4 6.5 17.2 12.9 7.5 2.9 2.2 0.0 0.0 49.6

1.204 Flow Reduction 20-

40MW Loss 

0.0 0.0 0.0 0.4 6.5 17.2 13.0 7.6 2.9 2.2 0.0 0.0 49.9

1.5 September 

maintenance outages 

0.0 0.0 0.0 0.4 6.1 14.3 6.4 4.1 3.9 1.1 0.0 0.0 36.3

2 1-mm wedgewire 

screen 

0.0 0.0 0.0 0.5 7.9 27.7 26.6 14.8 6.4 4.9 0.0 0.0 88.8

3 1.5-mm wedgewire 

screen 

0.0 0.0 0.0 0.5 8.3 28.2 26.6 14.8 6.4 4.9 0.0 0.0 89.7

4 2-mm wedgewire 

screen 

0.0 0.0 0.0 0.5 8.3 28.3 26.5 14.8 6.4 4.9 0.0 0.0 89.8

5 3-mm wedgewire 

screen 

0.0 0.0 0.0 0.5 8.3 28.2 26.5 14.8 6.4 4.9 0.0 0.0 89.7

6 6-mm wedgewire 

screen 

0.0 0.0 0.0 0.5 8.3 28.2 26.5 14.8 6.4 4.9 0.0 0.0 89.6

7 9-mm wedgewire 

screen 

0.0 0.0 0.0 0.5 8.3 28.2 26.5 14.8 6.4 4.9 0.0 0.0 89.6

8 1-mm mesh 

Ristroph screen

0.0 0.0 0.0 0.4 4.8 8.7 6.9 4.8 1.5 1.0 0.0 0.0 27.9

9 1.5mm mesh 

Ristroph screen

0.0 0.0 0.0 0.4 5.9 11.0 6.9 4.8 1.5 1.0 0.0 0.0 31.5

10 2-mm mesh 

Ristroph screen

0.0 0.0 0.0 0.4 6.1 12.8 7.0 4.8 1.5 1.0 0.0 0.0 33.5

11 3-mm mesh 

Ristroph screen

0.0 0.0 0.0 0.4 6.2 14.1 7.0 4.8 1.5 1.0 0.0 0.0 34.9

12 6-mm mesh 

Ristroph screen

0.0 0.0 0.0 0.4 6.1 14.3 6.4 4.1 1.3 1.1 0.0 0.0 33.8

13 9-mm mesh 

Ristroph screen

0.0 0.0 0.0 0.3 5.9 13.6 5.8 3.4 1.3 1.2 0.0 0.0 31.5

14 Aquatic Filter Barrier 0.0 0.0 0.0 0.5 9.9 30.2 25.1 13.8 6.0 4.8 0.0 0.0 90.4

15 NYSDEC Proposed 

Project – min SW 

0.0 0.0 0.0 0.5 10.6 33.3 27.1 14.8 6.3 4.8 0.0 0.0 97.6

15.5 NYSDEC Proposed 

Project – max SW 

0.0 0.0 0.0 0.5 10.4 32.8 26.8 14.6 6.3 4.8 0.0 0.0 96.2
22

Table 5. Monthly and annual total percent reduction in equivalent age 1 losses of 

impinged RIS Associated with certain alternative intake technologies for Units 2 and 3. 

Reduction calculated from regulatory baseline. 

Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Total 

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

1 Current technology 

6x12mm 

8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 80.2 

1.001 Flow Reduction 

0MW Loss 

8.8 9.6 12.0 6.7 7.4 8.5 4.0 4.2 4.4 3.9 4.7 6.5 80.7 

1.101 Flow Reduction 

10MW Loss 

8.8 9.6 12.0 6.7 7.9 9.7 4.3 4.4 4.7 4.4 5.0 6.5 84.0 

1.202 Flow Reduction 

20MW Loss 

8.8 9.6 12.0 6.7 7.9 9.9 4.4 4.5 4.8 4.4 5.0 6.5 84.7 

1.203 Flow Reduction 20-

30MW Loss 

8.8 9.6 12.0 6.7 7.9 10.0 4.5 4.6 4.9 4.4 5.0 6.5 85.0 

1.204 Flow Reduction 20-

40MW Loss 

8.8 9.6 12.0 6.7 7.9 10.0 4.5 4.7 4.9 4.4 5.0 6.5 85.0 

1.5 September 

maintenance outages 

8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 5.6 3.8 4.6 6.3 81.3 

2 1-mm wedgewire 

screen 

9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 99.9 

3 1.5-mm wedgewire 

screen 

9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 99.9 

4 2-mm wedgewire 

screen 

9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 99.9 

5 3-mm wedgewire 

screen 

9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 99.9 

6 6-mm wedgewire 

screen 

9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 99.9 

7 9-mm wedgewire 

screen 

9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 99.9 

8 1-mm mesh 

Ristroph screen

8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 80.2 

9 1.5mm mesh 

Ristroph screen

8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 80.2 

10 2-mm mesh 

Ristroph screen

8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 80.2 

11 3-mm mesh 

Ristroph screen

8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 80.2 

12 6-mm mesh 

Ristroph screen

8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 80.2 

13 9-mm mesh 

Ristroph screen

8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 80.2 

14 Aquatic Filter Barrier 9.4 10.3 12.9 8.0 9.5 11.7 5.3 5.5 5.7 4.9 5.5 7.6 96.1 

15 NYSDEC Proposed 

Project –low SW 

flow 

9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 99,8 

15.5 NYSDEC Proposed 

Project – high SW 

flow 

9.6 10.5 13.1 8.2 9.9 12.6 5.5 5.7 6.0 5.0 5.7 7.7 99.5 
23

Table 6. Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and production forgone (kg) dimpingement for alternative intake technology for Units 2 and 3. 

Case Taxon Equivalent Age 1 (millions) Equivalent Yield 

(kg) 

 Production Forgone (kg) 

 Ent Imp Total Ent Imp Total Ent Imp Total 

Regulatory Baseline 

0 Bay anchovy 2.332 0.014 2.346 0 0 0 5,628 2 5,630 American shad 0.000 0.000 0.000 14 9 23 368 38 400 Striped bass 0.571 0.048 0.619 213,460 25,942 239,402 660,935 50,960 711,890 Atlantic tomcod 0.046 0.002 0.047 0 0 0 12,656 47 12,700 White perch 0.279 0.399 0.678 153 322 475 12,301 13,048 25,340 Alosa sp 0.042 0.021 0.062 135 32 167 8,318 621 8,930 Total 3.270 0.484 3.754 213,762 26,306 240,068 700,206 64,716 764,92

Alternative Baseline 

0.5 Bay anchovy 2.332 0.484 2.817 0 26,306 26,306 5,628 64,716 70,340.5 American shad 0.000 0.003 0.003 14 13 27 368 237 600.5 Striped bass 0.247 0.000 0.247 102,547 1 102,549 285,377 25 285,400.5 Atlantic tomcod 0.042 0.001 0.043 0 0 0 10,510 0 10,510.5 White perch 0.171 0.003 0.174 97 1,526 1,623 7,548 2,997 10,540.5 Alosa sp 0.042 0.402 0.444 135 325 459 8,318 13,059 21,370.5 Total 2.834 0.894 3.728 102,793 28,171 130,964 317,749 81,035 398,78

Existing technology 

1 Bay anchovy 2.223 0.000 2.223 0 0 0 5,373 7 5,381 American shad 0.000 0.039 0.039 12 32 44 340 1,277 1,611 Striped bass 0.214 0.003 0.217 88,821 0 88,821 247,082 0 247,081 Atlantic tomcod 0.011 0.000 0.011 0 3 3 2,963 10 2,971 White perch 0.151 0.000 0.151 83 1 85 6,649 24 6,671 Alosa sp 0.039 0.056 0.094 125 3,114 3,239 7,761 7,783 15,541 Total 2.637 0.098 2.735 89,042 3,149 92,191 270,168 9,102 279,27
24

Table 6 (continued). Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and production foentrainment and impingement for alternative intake technology for Units 2 and 3. 

Flow Reduction 0MW Loss 

1.001 Bay anchovy 2.220 0.001 2.222 0 0 0 5,369 0 5,361.001 American shad 0.000 0.003 0.003 12 1,457 1,469 339 2,859 3,191.001 Striped bass 0.189 0.048 0.236 77,014 1,503 78,517 217,685 4,345 222,031.001 Atlantic tomcod 0.011 0.002 0.013 0 10 10 2,938 188 3,121.001 White perch 0.139 0.002 0.142 76 0 76 6,145 0 6,141.001 Alosa sp 0.038 0.038 0.076 125 31 156 7,729 1,244 8,971.001 Total 2.597 0.094 2.691 77,227 3,001 80,228 240,205 8,636 248,84

Flow Reduction 10MW Loss 

1.101 Bay anchovy 1.770 0.000 1.770 0 2 2 4,287 9 4,291.101 American shad 0.000 0.000 0.000 10 1 11 263 20 281.101 Striped bass 0.224 0.000 0.225 90,338 0 90,338 259,234 6 259,231.101 Atlantic tomcod 0.009 0.035 0.044 0 28 28 2,571 1,137 3,701.101 White perch 0.142 0.044 0.185 79 1,452 1,531 6,235 4,133 10,361.101 Alosa sp 0.030 0.006 0.036 96 1,411 1,507 5,952 2,774 8,721.101 Total 2.175 0.085 2.260 90,522 2,895 93,417 278,542 8,077 286,61

Flow Reduction 20MW Loss 

1.202 Bay anchovy 1.589 0.002 1.591 0 10 10 3,844 179 4,021.202 American shad 0.000 0.002 0.002 9 0 9 239 0 231.202 Striped bass 0.229 0.001 0.231 90,633 0 90,633 265,119 0 265,111.202 Atlantic tomcod 0.008 0.003 0.011 0 1,404 1,404 2,443 2,761 5,201.202 White perch 0.143 0.000 0.143 79 0 79 6,316 6 6,321.202 Alosa sp 0.027 0.044 0.071 88 1,455 1,544 5,482 4,160 9,641.202 Total 1.997 0.052 2.049 90,809 2,869 93,678 283,443 7,106 290,54
25

Table 6 (continued). Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and production foentrainment and impingement for alternative intake technology for Units 2 and 3. 

Flow Reduction 20-30MW Loss 

1.203 Bay anchovy 1.493 0.035 1.527 0 28 28 3,608 1,129 4,731.203 American shad 0.000 0.043 0.043 8 1,444 1,453 228 4,103 4,331.203 Striped bass 0.227 0.000 0.227 88,682 2 88,684 261,962 8 261,971.203 Atlantic tomcod 0.008 0.000 0.008 0 1 1 2,394 19 2,411.203 White perch 0.142 0.001 0.143 77 0 77 6,250 0 6,251.203 Alosa sp 0.026 0.004 0.030 85 9 94 5,287 181 5,461.203 Total 1.895 0.083 1.978 88,853 1,485 90,337 279,729 5,440 285,16

Flow Reduction 20-40MW Loss 

1.204 Bay anchovy 1.480 0.003 1.482 0 1,402 1,402 3,576 2,757 6,331.204 American shad 0.000 0.000 0.000 8 0 8 227 5 231.204 Striped bass 0.226 0.002 0.228 88,330 9 88,340 261,118 175 261,291.204 Atlantic tomcod 0.008 0.002 0.010 0 0 0 2,389 0 2,391.204 White perch 0.141 0.000 0.141 77 2 79 6,232 8 6,241.204 Alosa sp 0.026 0.079 0.105 85 1,469 1,554 5,271 5,220 10,491.204 Total 1.881 0.085 1.966 88,501 2,882 91,383 278,814 8,166 286,97
26

Table 6 (continued). Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and production foentrainment and impingement for alternative intake technology for Units 2 and 3. 

1-mm wedgewire screen 

2 Bay anchovy 0.145 0.001 0.146 0 0 0 395 0 392 American shad 0.000 0.000 0.000 0 1 2 11 6 12 Striped bass 0.071 0.002 0.073 21,359 1,154 22,513 82,075 2,282 84,352 Atlantic tomcod 0.000 0.000 0.000 0 0 0 48 6 52 White perch 0.081 0.030 0.111 36 24 60 3,629 994 4,622 Alosa sp 0.005 0.003 0.007 14 6 20 1,105 116 1,222 Total 0.301 0.036 0.337 21,408 1,186 22,594 87,262 3,404 90,66

1.5-mm wedgewire screen 

3 Bay anchovy 0.148 0.036 0.184 0 1,186 1,186 406 3,404 3,803 American shad 0.000 0.000 0.000 0 0 1 11 7 13 Striped bass 0.047 0.000 0.047 14,385 0 14,385 54,238 1 54,233 Atlantic tomcod 0.000 0.000 0.000 0 0 0 48 0 43 White perch 0.078 0.000 0.078 34 59 93 3,460 116 3,573 Alosa sp 0.005 0.030 0.035 14 24 38 1,145 995 2,143 Total 0.278 0.066 0.344 14,434 1,270 15,704 59,308 4,522 63,83

2-mm wedgewire screen 

4 Bay anchovy 0.150 0.000 0.150 0 0 0 410 0 414 American shad 0.000 0.001 0.001 0 1 1 11 48 54 Striped bass 0.043 0.000 0.043 13,360 0 13,360 50,146 0 50,144 Atlantic tomcod 0.000 0.000 0.000 0 0 0 48 0 44 White perch 0.077 0.000 0.077 34 0 34 3,437 1 3,434 Alosa sp 0.005 0.002 0.007 14 120 135 1,162 297 1,454 Total 0.275 0.004 0.279 13,409 122 13,531 55,214 346 55,56
27

Table 6 (continued). Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and production foentrainment and impingement for alternative intake technology for Units 2 and 3. 

3-mm wedgewire screen 

4 Bay anchovy 0.150 0.000 0.150 0 0 0 412 0 415 American shad 0.000 0.000 0.000 0 59 59 12 116 125 Striped bass 0.043 0.002 0.045 13,449 61 13,510 50,344 173 50,515 Atlantic tomcod 0.000 0.000 0.000 0 0 0 49 7 55 White perch 0.078 0.000 0.078 35 0 35 3,479 0 3,475 Alosa sp 0.005 0.001 0.007 14 1 16 1,165 49 1,215 Total 0.277 0.004 0.280 13,499 122 13,620 55,460 346 55,80

6-mm wedgewire screen 

6 Bay anchovy 0.152 0.000 0.152 0 0 0 415 0 416 American shad 0.000 0.000 0.000 0 0 0 12 1 16 Striped bass 0.044 0.000 0.044 13,654 0 13,654 50,801 0 50,806 Atlantic tomcod 0.000 0.001 0.002 0 1 1 50 48 96 White perch 0.078 0.002 0.080 35 61 96 3,489 173 3,666 Alosa sp 0.005 0.000 0.005 14 59 74 1,165 116 1,286 Total 0.279 0.004 0.282 13,704 121 13,825 55,932 339 56,27

9-mm wedgewire screen 

7 Bay anchovy 0.152 0.000 0.152 0 0 0 415 7 427 American shad 0.000 0.000 0.000 0 0 0 12 0 17 Striped bass 0.044 0.000 0.044 13,666 0 13,666 50,831 0 50,837 Atlantic tomcod 0.000 0.000 0.000 0 59 59 51 116 167 White perch 0.078 0.000 0.078 35 0 35 3,489 0 3,497 Alosa sp 0.005 0.002 0.007 14 61 75 1,165 174 1,337 Total 0.279 0.002 0.281 13,716 120 13,836 55,962 298 56,26
28

Table 6 (continued). Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and production foentrainment and impingement for alternative intake technology for Units 2 and 3. 

1-mm alternative Ristroph screen 

8 Bay anchovy 2.069 0.001 2.071 0 1 1 5,015 48 5,068 American shad 0.000 0.002 0.002 12 61 73 336 173 508 Striped bass 0.331 0.000 0.331 122,560 0 122,560 383,052 0 383,058 Atlantic tomcod 0.010 0.000 0.010 0 0 0 2,888 1 2,888 White perch 0.207 0.000 0.207 110 0 110 9,138 0 9,138 Alosa sp 0.039 0.000 0.039 125 0 125 7,748 7 7,758 Total 2.656 0.004 2.659 122,807 63 122,870 408,177 230 408,40

1.5mm alternative Ristroph screen 

9 Bay anchovy 2.072 0.000 2.072 0 0 0 5,022 1 5,029 American shad 0.000 0.000 0.000 12 0 12 336 0 339 Striped bass 0.252 0.001 0.254 99,631 1 99,632 291,515 48 291,569 Atlantic tomcod 0.010 0.002 0.012 0 61 61 2,886 173 3,059 White perch 0.189 0.003 0.192 102 13 115 8,351 237 8,589 Alosa sp 0.039 0.000 0.039 125 59 184 7,752 117 7,869 Total 2.562 0.006 2.568 99,870 134 100,004 315,862 577 316,43

2-mm alternative Ristroph screen 

10 Bay anchovy 2.074 0.050 2.124 0 1,575 1,575 5,029 4,555 9,5810 American shad 0.000 0.003 0.003 12 13 25 336 237 5710 Striped bass 0.225 0.000 0.225 91,561 1 91,562 259,298 25 259,3210 Atlantic tomcod 0.010 0.001 0.012 0 0 0 2,882 0 2,8810 White perch 0.173 0.003 0.175 95 1,526 1,621 7,603 2,997 10,6010 Alosa sp 0.039 0.042 0.081 125 34 159 7,757 1,288 9,0410 Total 2.520 0.100 2.620 91,793 3,149 94,943 282,904 9,103 292,00
29

Table 6 (continued). Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and production foentrainment and impingement for alternative intake technology for Units 2 and 3. 

3-mm alternative Ristroph screen 

11 Bay anchovy 2.081 0.001 2.082 0 0 0 5,045 0 5,0411 American shad 0.000 0.003 0.003 12 1,526 1,539 338 2,997 3,3311 Striped bass 0.212 0.050 0.262 87,815 1,575 89,389 244,813 4,555 249,3611 Atlantic tomcod 0.010 0.003 0.013 0 13 13 2,876 237 3,1111 White perch 0.157 0.003 0.160 88 0 88 6,896 0 6,8911 Alosa sp 0.039 0.040 0.078 125 33 158 7,760 1,309 9,0611 Total 2.499 0.100 2.598 88,040 3,147 91,186 267,727 9,100 276,82

6-mm alternative Ristroph screen 

12 Bay anchovy 2.223 0.003 2.226 0 13 13 5,373 237 5,6112 American shad 0.000 0.003 0.003 12 0 12 340 0 3412 Striped bass 0.214 0.001 0.216 88,821 0 88,821 247,082 0 247,0812 Atlantic tomcod 0.011 0.003 0.013 0 1,526 1,526 2,963 2,997 5,9612 White perch 0.151 0.000 0.151 83 0 83 6,649 7 6,6512 Alosa sp 0.039 0.050 0.089 125 1,579 1,704 7,761 4,591 12,3512 Total 2.637 0.061 2.697 89,042 3,118 92,160 270,168 7,834 278,00

9-mm alternative Ristroph screen 

13 Bay anchovy 2.254 0.003 2.257 0 1,526 1,526 5,443 2,997 8,4413 American shad 0.000 0.000 0.000 13 0 13 342 7 3413 Striped bass 0.229 0.001 0.230 95,992 3 95,995 264,220 55 264,2713 Atlantic tomcod 0.014 0.001 0.014 0 0 0 4,083 0 4,0813 White perch 0.155 0.000 0.155 86 1 87 6,818 3 6,8213 Alosa sp 0.039 0.091 0.129 125 1,606 1,731 7,765 5,832 13,5913 Total 2.690 0.095 2.785 96,217 3,136 99,353 288,671 8,894 297,56
30

Table 6 (continued). Average annual losses of age-1 equivalent fish (millions) lost yield (kg), and production foentrainment and impingement for alternative intake technology for Units 2 and 3. 

Aquatic Filter Barrier 

14 Bay anchovy 0.405 0.001 0.406 0 0 0 989 0 9814 American shad 0.000 0.000 0.000 1 0 1 37 2 314 Striped bass 0.034 0.002 0.036 13,570 1,042 14,611 39,598 2,049 41,6414 Atlantic tomcod 0.001 0.000 0.001 0 0 0 173 2 1714 White perch 0.030 0.016 0.046 16 13 29 1,310 538 1,8414 Alosa sp 0.005 0.001 0.006 14 1 15 1,103 23 1,1214 Total 0.474 0.020 0.494 13,600 1,056 14,657 43,210 2,614 45,82

NYSDEC Proposed Project – min SW 

15 Bay anchovy 0.108 0.020 0.128 0 1,056 1,056 261 2,614 2,8715 American shad 0.000 0.000 0.000 1 0 1 17 8 215 Striped bass 0.025 0.000 0.025 9,337 0 9,337 28,624 1 28,6215 Atlantic tomcod 0.002 0.000 0.002 0 0 0 553 0 5515 White perch 0.012 0.000 0.012 7 65 72 518 129 6415 Alosa sp 0.002 0.017 0.018 6 13 19 362 538 9015 Total 0.149 0.037 0.185 9,350 1,135 10,486 30,334 3,289 33,62

NYSDEC Proposed Project - max SW 

15.5 Bay anchovy 0.105 0.000 0.105 0 0 0 253 0 2515.5 American shad 0.000 0.002 0.002 1 2 3 16 80 915.5 Striped bass 0.023 0.000 0.023 8,254 2 8,256 26,307 0 26,3015.5 Atlantic tomcod 0.001 0.000 0.001 0 38 38 183 0 1815.5 White perch 0.012 0.000 0.012 6 128 134 517 0 5115.5 Alosa sp 0.002 0.003 0.005 6 696 702 370 494 8615.5 Total 0.141 0.006 0.147 8,267 866 9,133 27,646 574 28,21
31

4. Cumulative benefits of I&E reductions 

This section provides an evaluation of the cumulative benefits of I&E reductions 

over the expected lifetimes of Units 2 and 3 associated with the immediate installation of 

cylindrical wedgewire screens versus the 2029 completion date for construction of the 

NYSDEC Proposed Project.13 This evaluation accounts for both expected annual 

reductions in I&E losses and for the time required to install alternative intake 

technologies. The schedule for the NYSDEC Proposed Project was derived by 

ENERCON with input from Entergy’s counsel and Spectra Energy14. Key factors 

influencing this schedule include the technical complexity of the project, permitting 

requirements, and to likely litigation relating to local zoning ordinances. 

Cylindrical wedgewire screens, which are nearly as effective as the NYSDEC 

Proposed Project at reducing I&E losses (as demonstrated in Section 3) could be installed 

relatively quickly. This benefits analysis assumes, consistent with a proposal from 

Entergy, that cylindrical wedgewire screens could be installed at Unit 2 by 2013 and at 

Unit 3 by 2015. Because they can be installed much sooner, reductions in I&E losses 

could begin immediately rather than being deferred for an extended period while 

technical feasibility and permitting issues associated with the NYSDEC Proposed Project 

are resolved. Because of the earlier installation date, cumulative reductions in I&E losses 

over the lifetimes of Units 2 and 3 associated with cylindrical wedgewire screens are 

estimated to be more than two times greater than reductions that could be achieved with 

the NYSDEC Proposed Project. Detailed documentation of methods and results is 

provided in Appendix A. 

4.1 Comparison of immediate installation of cylindrical 

wedgewire screens to delayed installation of the NYSDEC 

Proposed Project 

The construction schedule was provided by counsel to Entergy and by 

ENERCON. It was assumed for this analysis that cylindrical wedgewire screens could be 

installed and operating at Unit 2 in 2013 and at Unit 3 in 2015. It was assumed that the 

NYSDEC Proposed Project would become operational at both units in 2029. It was 

assumed that Unit 2 would be retired in 2033 and Unit 3 would be retired in 2035, 

consistent with their respective NRC licenses. 

Table 7 shows the cumulative estimated total I&E losses and age-1 equivalent 

losses from 2013 through 2035, for Unit 2 and Unit 3, for the regulatory baseline, for the 

existing technology, for the 6 cylindrical wedgewire screen scenarios evaluated in this 

report, and for the NYSDEC Proposed Project. Table 7 also shows, for each scenario, the 

 

13 Aquatic filter barriers were not included in this analysis because, as discussed by ENERCON (section 

5.4.1), significant operational and nuclear safety/licensing issues associated with this technology would 

have to be resolved prior to installation. 

14 Counsel informed us that Spectra Energy is the parent company of Algonquin Gas Transmission, LLC, 

the owner of the natural gas pipeline system that traverses the IPEC property. 
32

percent reduction in cumulative estimated total I&E losses and age-1 equivalent losses 

compared to the regulatory baseline. Finally, Table 7 shows the “savings ratio” for each 

scenario. As discussed in Appendix A, the savings ratio measures the relative 

incremental reduction in cumulative losses for each technology, as compared to the 

existing technology at Units 2 and 3. 

Table 7 shows that, because of the time required to resolve technical feasibility 

and permitting issues associated with the NYSDEC Proposed Project, implementing this 

project would result in only a 55% reduction in estimated entrainment losses and age-1 

equivalent losses compared to the regulatory baseline. The reason for this is because for 

most of the years between 2013 and 2029 the existing technology would still be 

operating. In contrast, for all of the wedgewire screen scenarios, estimated cumulative 

total entrainment losses would be reduced by 78% and estimated cumulative age-1 

equivalent losses due to entrainment would be reduced by 88%. Reductions in 

impingement would also be much greater (99% for both losses and age-equivalents) for 

wedgewire screens than for the NYSDEC Proposed Project (88% for losses and 87% for 

age-1 equivalents). The savings ratios for the 6 cylindrical wedgewire screens scenarios 

are all greater than 2.5 for entrainment and equal to 3.0 for impingement, indicating that 

these screens would be more than twice as effective as the NYSDEC Proposed Project at 

reducing entrainment losses and three times as effective at reducing impingement losses 

compared to the losses associated with the existing technology. 

One of the fundamental principles of natural resource restoration is that resources 

that are provided in the future are less valuable than resources that are provided in the 

present (NOAA 1997, French McCay and Rowe 2003). For example, a given quantity of 

restored habitat is considered to be less valuable if it is provided 10 years in the future 

than if it is provided 2 years in the future. To compare ecological benefits of alternative 

restoration projects that may be completed at different times in the future, trustee 

agencies use a discount rate of 3% to convert the future values of all of the alternatives to 

their present value. This is the same procedure that is used in economics to calculate the 

present value of investments or costs that will occur in the future (NOAA 1997). 

Both cylindrical wedgewire screens and the NYSDEC Proposed Project will 

provide potential ecological benefits related to reductions in I&E losses. However, the 

benefits accruing from the NYSDEC Proposed Project would occur much later than the 

benefits accruing from immediate installation of cylindrical wedgewire screens. Table 8 

presents the same comparisons as Table 7, but with values for future I&E losses and 

reductions in losses discounted by 3% per year. With discounting, the comparative 

benefits of immediate installation of cylindrical wedgewire screens are even greater than 

the undiscounted benefits. The discounted reductions in entrainment and impingement 

losses for wedgewire screens are, respectively, 77% and 98%, compared to 50% and 86% 

for the NYSDEC Proposed Project. The discounted reduction in age-1 equivalent 

entrainment for wedgewire screens is 87% for entrainment and 98% for impingement, 

compared to 50% and 86% for the NYSDEC Proposed Project. The discounted savings 

ratios for cylindrical wedgewire screens are 2.7 for total entrainment losses, 3.3 for 

equivalent age-1 entrainment losses, and 3.8 for both total impingement losses and 

equivalent age-1 impingement losses. 
33

Table 7. Cumulative I&E losses, percent reductions in losses, and savings ratios for alternative intake technolog

Units 2 and 3. 

Scenario Undiscounted 

Year 

Technology 

Operationala 

Total Losses (millions) Equ

Number % 

Reduction 

Savings 

Ratio 

Numbe

Unit 2 Unit 3 

Entrainment Regulatory Baseline 26,931 0 71.91

Existing Technology 2013 2013 14,183 35 0 57.961-mm wedgewire screen 2013 2015 7,264 77 1.9 8.921.5-mm wedgewire screen 2013 2015 6,255 78 2.1 8.422-mm wedgewire screen 2013 2015 6,127 78 2.1 8.373-mm wedgewire screen 2013 2015 6,136 78 2.1 8.406-mm wedgewire screen 2013 2015 6,137 78 2.1 8.449-mm wedgewire screen 2013 2015 6,137 78 2.1 8.44NYSDEC Proposed Project 2029 2029 9,885 55 1.0 40

Impingement Regulatory Baseline 14.728 0 10.65

Existing Technology 2013 2013 1.549 82 0.0 1.091-mm wedgewire screen 2013 2015 0.125 99 3.0 0.081.5-mm wedgewire screen 2013 2015 0.125 99 3.0 0.082-mm wedgewire screen 2013 2015 0.125 99 3.0 0.083-mm wedgewire screen 2013 2015 0.125 99 3.0 0.086-mm wedgewire screen 2013 2015 0.125 99 3.0 0.089-mm wedgewire screen 2013 2015 0.125 99 3.0 0.08NYSDEC Proposed Project 2029 2029 1.073 88 1.0 0.76

aConstruction schedules provided by ENERCON and counsel to Entergy 
34

Table 8. Cumulative I&E losses, percent reductions in losses, and savings ratios for alternative intake technolog

Units 2 and 3, with post-2013 reductions discounted at 3% per year. 

Scenario Discounted 3% per year 

Year 

Technology 

Operationala 

Total Losses (millions) Equ

Number 

% 

Reduction 

Savings 

Ratio Numbe

Unit 2 Unit 3 

Entrainment Regulatory Baseline 19,919 0 53.18

Existing Technology 2013 2013 10,494 35 0.0 42.881-mm wedgewire screen 2013 2015 5,456 76 2.4 7.171.5-mm wedgewire screen 2013 2015 4,721 77 2.6 6.82-mm wedgewire screen 2013 2015 4,627 77 2.7 6.773-mm wedgewire screen 2013 2015 4,634 77 2.7 6.796-mm wedgewire screen 2013 2015 4,635 77 2.7 6.829-mm wedgewire screen 2013 2015 4,635 77 2.7 6.82NYSDEC Proposed Project 2029 2029 8,007 50 1.0 32.54

Impingement Regulatory Baseline 10.892 0 7.8

Existing Technology 2013 2013 1.146 82 0.0 0.811-mm wedgewire screen 2013 2015 0.109 98 3.8 0.071.5-mm wedgewire screen 2013 2015 0.109 98 3.8 0.072-mm wedgewire screen 2013 2015 0.109 98 3.8 0.073-mm wedgewire screen 2013 2015 0.109 98 3.8 0.076-mm wedgewire screen 2013 2015 0.109 98 3.8 0.079-mm wedgewire screen 2013 2015 0.109 98 3.8 0.07NYSDEC Proposed Project 2029 2029 0.87 86 1.0 0.61

aConstruction schedule provided by ENERCON and counsel to Entergy. 
35

4.2 Sensitivity analysis 

 A sensitivity analysis was performed to determine the level of confidence in the 

cumulative biological benefits associated with cylindrical wedgewire screens as 

compared to the NYSDEC Proposed Project. This analysis focused on entrainment, 

because all wedgewire screen configurations evaluated in this report should reduce 

impingement to very low levels (Section 3 and Table 3). The avoidance and survival 

factors used to estimate potential entrainment loss reductions for cylindrical wedgewire 

screens are well-supported by laboratory studies, and are also supported by a full-scale 

field study performed at the Eddystone Generating Station on the Delaware River (see 

Appendix B). However, cylindrical wedgewire screens have not been field-tested at 

Indian Point. To assess the level of confidence in the relative biological benefits 

calculations presented in Tables 7 and 8, additional calculations were performed using 

alternative avoidance and survival factors. These alternative avoidance and survival 

factors produce a lower entrainment loss percentages than the curves used to generate 

tables 7 and 8. As a result, they provide a conservative, lower range of entrainment loss 

percentages that nevertheless highlights the superior cumulative benefits of cylindrical 

wedgewire screens as compared to the NYSDEC Proposed Project. 

 As discussed in Appendix A, the sensitivity analysis documented in this section 

utilized 8 alternative length-specific avoidance curves and 3 alternative assumptions 

about the survival rates of excluded (i.e., impinged) larvae. The most extreme set of 

alternative assumptions assumes that there is no avoidance of the screen by larvae or 

juveniles, and no survival of impinged larvae and juveniles. Four slot widths ranging 

from 1 mm to 9 mm were selected for analysis. 

 Results of the sensitivity analysis are shown in Figure 2. In Figure 2, discounted 

percent reductions in cumulative age-1 equivalent losses for each combination of 

avoidance and survival assumptions are compared to the corresponding reduction for the 

NYSDEC Proposed Project. The percent reductions for cylindrical wedgewire screens 

fall below the value for the NYSDEC Proposed Project only for avoidance curve 8, 

which assumes no avoidance of the screen by larvae or juveniles of any length class. 

Since data from studies of cylindrical wedgewire screens have consistently demonstrated 

that avoidance occurs (see Appendix B), curve 8 is not realistic. For all other avoidance 

curves and exclusion survival assumptions, cumulative percent reductions in entrainment 

losses are greater for cylindrical wedgewire screens than for the NYSDEC Proposed 

Project. Hence, the sensitivity analysis provides confidence that even using very 

conservative survival and avoidance factors, immediate installation of cylindrical 

wedgewire screens would provide greater reductions in I&E losses than later installation 

of the NYSDEC Proposed Project. 
36

Figure 2. Sensitivity of cumulative percent reduction estimates for cylindrical wedgewire screens to alternative lavoidance curves and assumptions concerning the survival of impinged larvae and juveniles. Avoidance curve 1 developed in Appendix B. Curve 8 is the worst-case assumption that no avoidance occurs. The alternative impingassumptions are 100% survival (Sx=100%), survival equal to the survival of small fish impinged on fine mesh sc

screen), and 0% survival (Sx=0). 

1‐mm Slot

0

20406080

100

CumulativeDiscounted

Entrainment

%ReductionEquiv Age 1

Sx = 100% 86.4 84.2 81.9 79.2 77.4 76.7 76.4 75.8Sx = FM screen 85.2 82.5 79.4 75.3 71.4 67.9 63.5 29.2Sx = 0 84.7 82.0 78.8 74.6 70.4 66.6 61.5 10.7Closed Cycle 50.1 50.1 50.1 50.1 50.1 50.1 50.1 50.1

12345678

3‐mm Slot

0

20406080

100

CumulativeDiscounted

Entrainment

%ReductionEquiv Age 1

Sx = 100% 87.2 85.2 83.2 80.7 78.5 76.4 74.Sx = FM screen 86.5 84.4 82.2 79.5 76.7 73.8 69.Sx = 0 86.0 83.9 81.7 78.9 75.9 72.7 67.Closed Cycle 50.1 50.1 50.1 50.1 50.1 50.1 50.

1234567

6‐mm Slot

0

20406080

100

CumulativeDiscounted

Entrainment

%ReductionEquiv Age 1

Sx = 100% 87.2 85.1 82.9 80.3 77.5 74.7 70.8 55.2Sx = FM screen 86.5 84.5 82.3 79.5 76.7 73.8 69.5 34.3Sx = 0 86.0 84.0 81.8 79.1 76.2 73.2 68.7 19.6Closed Cycle 50.1 50.1 50.1 50.1 50.1 50.1 50.1 50.1

12345678

9‐mm Slot

0

20406080

100

CumulativeDiscounted

Entrainment

%ReductionEquiv Age 1

Sx = 100% 87.2 85.1 82.9 80.2 77.4 74.5 70.Sx = FM screen 86.5 84.5 82.2 79.5 76.7 73.7 69.4 Sx = 0 86.0 84.0 81.8 79.1 76.2 73.3 68.Closed Cycle 50.1 50.1 50.1 50.1 50.1 50.1 50.

1234567
37

5. Potential I&E impacts of IPEC operations on Hudson River 

fish populations, with and without alternative technologies 

 

All of the calculations discussed in the previous section assume that I&E losses 

are directly proportional to reductions in the subsequent abundance of older fish. For 

example, if on average 1% of larvae lost due to entrainment would be expected to survive 

to age 1, then the loss of 100,000 larvae is assumed to reduce the number of 1-year-old 

fish present in the river by 1000. Employing an intake technology that reduces 

entrainment losses to 10,000 larvae is assumed to save 900 future one-year-old fish (i.e., 

the survivors among the 90,000 larvae that were not entrained due to the new technology) 

that would have been lost without the new technology. 

These are hypothetical calculations that fail to account for environmental and 

biological variability, density-dependent mortality, and other factors that disrupt the 

presumed relationship between the losses of early life stages and subsequent abundance 

of older fish. Many of these factors are discussed in Entergy’s Adverse Environmental 

Impact (“AEI”) Report (Barnthouse et al. 2008). The AEI report analyzed 30 years of 

data relating the abundance of the eight RIS species discussed in this report to the 

operations of Units 2 and 3, and found no evidence that entrainment at these stations had 

any measurable effect on the abundance of any species. If existing levels of I&E losses 

have not caused a measurable decline in the abundance of any RIS, then reducing those 

losses through installation of new technologies would not be expected to cause a 

measurable increase in the abundance of any species. 

 Section 5.1 provides a summary of the AEI report. Section 5.2 discusses a new 

analysis (documented in Appendix C to this report) that supports the conclusions of the 

AEI report by demonstrating, using data from the Hudson River surveys, that increasing 

the abundance of larvae in the Hudson River by eliminating all entrainment losses at 

Units 2 and 3 would not produce a measurable increase in the abundance of juvenile fish. 

Appendix D provides additional supporting information that addresses issues raised in 

NYSDEC’s Final Environmental Impact Statement (“FEIS”). 

 As set forth below, no appreciable population-level impacts would be achieved by 

implementing any of the technology alternatives considered in this report, including the 

NYSDEC Proposed Project. 

5.1 Entergy’s AEI report 

Entergy’s AEI report evaluated whether entrainment and impingement caused by 

the operation of Units 2 and 3 resulted in AEI, on Hudson River fish populations and 

communities. The report used biologically-based definitions of AEI that are consistent 

with established definitions and standards of ecological risk assessment and fisheries 

management. 

 
38

The approach involved three elements. First, the extensive Hudson River 

fisheries data-sets were evaluated to determine: (1) whether changes in the status of 

species of interest identified by NYSDEC have occurred since Units 2 and 3 began 

commercial operation, (2) whether cooling-water withdrawals by Units 2 and 3 during 

this period could have been responsible for any such changes, or (3) whether alternative 

stressors including striped bass predation, zebra mussels, and harvesting are the more 

probable cause of perceived changes. 

Second, a widely-accepted method for quantifying the impacts of harvesting on 

the sustainability of fish populations, termed the Spawning Stock Biomass per Recruit 

(SSBPR) model, was used to determine whether entrainment and impingement caused by 

the operation of Units 2 and 3 could have adversely affected the sustainability of the 

Hudson River striped bass and American shad populations. 

Third, long-term trends in the abundance of all Hudson River fish species for 

which adequate data were available were examined to determine whether species with 

high susceptibility to entrainment at Units 2 and 3 are more likely to have declined in 

abundance over the past 30 years than are species with low susceptibility to entrainment. 

All three elements of the assessment supported a conclusion that Units 2 and 3 

have not caused an AEI. Evaluation of alternative hypotheses concerning the causes of 

changes in abundance of Hudson River fish populations found no evidence supporting the 

hypothesis that Units 2 and 3 contributed to these changes. Instead, the evaluation shows 

that overharvesting is the most likely cause of recent declines in abundance of American 

shad, with striped bass predation being a potentially significant contributing factor. 

Increased predation by the rapidly growing Hudson River striped bass population is the 

most likely cause of recent declines in the abundance of Atlantic tomcod, river herring 

and bay anchovy. Striped bass predation probably contributed to the decline in 

abundance of white perch, although other unknown causes were also involved. 

5.2 Empirical assessment of expected population-level effects 

of reductions in entrainment losses due to alternative 

technologies 

As noted above, estimates of losses of age-1 equivalent fish are theoretical 

calculations based on estimates of the average fraction of entrained fish that would have 

survived to an age of 1 year. However, as shown in Entergy’s AEI Report, as 

summarized in Section 5.1, survival rates of early life stages of fish in the Hudson River 

are highly variable, and correlations between abundance indices for larvae and juveniles 

are often low. Hence, increasing the abundance of larvae through reductions in 

entrainment losses may lead to little or no increase in the abundance of older fish. To 

fully assess the relationship between estimated increases in larval abundance (expressed 

as equivalent age-1 fish) and actual increases in the abundance of one-year old fish, it 

would be necessary to obtain field measurements of increased larval abundance, together 

with estimates of the resulting change in abundance of one-year-old fish. 
39

For large natural ecosystems like the Hudson River estuary, it is not possible to 

experimentally increase the abundance of larvae and then observe the resulting increase 

in abundance of 1-year-old fish. However, the 30 years of historical data document 

naturally-occurring “experiments” in which the effects of increases in riverwide larval 

abundance (expressed in terms of age-1 equivalents) on changes in riverwide juvenile 

abundance can be measured. Increases and decreases in the abundance of larvae from 

one year to the next commonly occur, due to natural variability. Since the abundances of 

both larvae and juveniles of all RIS species are measured annually, these data can be used 

to determine whether, when the abundance of larvae increases from one year to the next, 

the abundance of juveniles also increases. These naturally-occurring experiments can be 

used to address the question of whether measurable changes in the abundance of juvenile 

and older fish can be expected from reducing entrainment losses of larvae at Units 2 and 

3. 

Specifically, year-to-year increases in the abundance of larval fish, as measured in the 

Long River Survey (“LRS”),15 can be compared to corresponding changes in juvenile 

abundance, as measured in “BSS”, and Fall Juvenile Survey (“FJS”).16 These surveys 

provide comprehensive and consistent estimates of long-term trends in the abundance of 

multiple life stages of important Hudson River fish populations, from 1974 through the 

present. Detailed descriptions of these surveys are provided in ASA (2007). 

If increases in larval abundance as measured in the LRS were regularly associated 

with increases in juvenile abundance as measured in the FSS and FJS, then it could be 

concluded that saving fish larvae by reducing entrainment could increase the subsequent 

abundance of juvenile and older fish. If, however, there is no relationship between larval 

abundance and subsequent juvenile abundance, then it is unlikely that increasing the 

number of larval fish present in the river will lead to an increase in the abundance of 

juvenile and older fish. 

5.2.1 Methods 

The relationship between increases in larval abundance and changes in abundance 

of older fish was investigated for American shad, river herring, striped bass, and white 

perch. Data for the remaining RIS were judged to be insufficient for this analysis. For 

each of the species addressed, the annual riverwide abundance of post yolk-sac larvae 

(“PYSL”), expressed in terms of age-1 equivalents, was calculated for the years 1974 

through 2005. The abundance of PYSL in each year was then compared to PYSL 

abundance in every other year. For example, PYSL abundance in 1974 was compared to 

PYSL abundance in all other years. Instances in which PYSL abundance in these years 

was greater than PYSL abundance in 1974 were identified. The same procedure was 

applied to all other years, e.g., PYSL abundance in 1984 was compared to PYSL 

 

15 The LRS samples eggs, larvae, and juvenile fish, weekly from April through July. The region between 

the George Washington Bridge and the Federal Dam at Troy has been sampled since 1974. In 1988, the 

LRS was extended to sample the region between the Battery and the George Washington Bridge. 

16 The BSS and FSS sample juvenile fish, during alternate weeks from June through October. Sampling is 

conducted from the George Washington Bridge to the Federal Dam. 
40

abundance in the years 1974-1983 and 1985-2005. Evaluating all pairs of years, rather 

than only adjacent years, eliminates any possible influence of long-term trends in 

abundance or survival of larvae on the outcome of the analysis. 

The difference in PYSL abundance between the higher and lower of each pair was 

calculated and used as a measure of increasing larval abundance, analogous to an increase 

that could occur due to implementation of an alternative intake technology at Units 2 and 

3. For each pair of years with an increase in PYSL abundance, the corresponding change 

in observed juvenile abundance between those years was calculated. Estimates of changes 

in juvenile abundance were based on the annual juvenile index of abundance from 

Entergy’s AEI report. 

The estimates of increases in PYSL abundance were converted to equivalent age1 fish using the same methods used in the technology evaluations (Section 2; Appendix 

A). Hence, the estimates of increases in PYSL abundance used in this analysis are 

directly comparable to the projections of potential increases in age-1 equivalents due to 

reduced entrainment losses. Table 9 shows, for each taxon, the maximum and minimum 

entrainment losses under the “existing technology” scenario, for the years 2001-2007. 

This range represents the maximum increase in age-1 equivalents that could have 

occurred, if no entrainment caused by operation of the Stations had occurred during this 

period. For those year-to-year increases in riverwide age-1 equivalents that fell within the 

range of potential annual increases in age-1 equivalents due to eliminating current IPEC 

entrainment losses, the corresponding changes in juvenile abundance were summarized. 

The changes in juvenile abundance for those pairs of years indicate the change in juvenile 

abundance that could be expected if current entrainment losses at Units 1 and 2 were 

eliminated. 

5.2.2 Results 

Figures 3 through 6 show, for each of the four taxa evaluated, the range of yearto-year increases in riverwide PYSL abundance calculated from historical data and the 

relative change in juvenile abundance associated with each increase. These figures also 

show the range of increases that would be expected to occur if current levels of 

entrainment losses at IPEC were eliminated. For all taxa, the range of projected increases 

in numbers of age-1 equivalents due to eliminating entrainment is very small compared to 

the range of year-to-year increases calculated from historical data. Within this small 

range, decreases in corresponding abundance of juveniles have occurred as frequently as 

increases. The estimated probability of observing an increase in juvenile abundance, 

when the increase in PYSL abundance is within the range that would be projected due to 

elimination of entrainment, is not significantly different than 50:50 for any of the four 

taxa evaluated (Appendix C). 

None of the technology alternatives evaluated in this report would completely 

eliminate entrainment. If reducing entrainment to zero would not produce a measurable 

increase in the actual abundance of juvenile or one-year-old fish, then reducing 

entrainment by a lesser amount would similarly produce no measurable increases in 
41

abundance. This result implies that none of the technology alternatives evaluated in this 

report would be expected to result in a demonstrable increase in juvenile abundance of 

American shad, river herring, striped bass or white perch. 
42

Table 9. Projected annual increases in age-1 equivalents due to eliminating current 

entrainment losses at Units 2 and 3 (Source: Appendix A to this report). 

Taxon Projected Range of Potential 

Annual Increases in Age-1 

Equivalents Due to Eliminating 

Current Entrainment Losses at 

Units 2 and 3 

Minimum 

Projected 

Annual 

Increase in 

Age-1 

Equivalents 

Maximum 

Projected 

Annual Increase 

in Age-1 

Equivalents 

River Herring 12,100 86,900 

American Shad 0 200 

Striped Bass 76,300 561,400 

White Perch 54,100 347,200 
43

-3

-2

-1

0

1

2

3

0

2,5005,0007,500

10,00012,50015,00017,50020,000

22,500

Projected Range of Potential Annual Increase in Age-1 Equivalents

Due to Eliminating Current IPEC Entrainment Losses

Observed Year-to-Year Increase in PYSL Abundance

(Expressed as Increase in Equivalent Age-1 Abundance)

O

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Figure 3. Observed year-to-year changes in riverwide juvenile abundance of American 

shad in response to observed year-to-year increases in riverwide post yolk-sac 

larval (PYSL) abundance. Based on all pairs of years (1985-2005) with observed 

positive change in abundance of PYSL. 
44

-4

-3

-2

-1

0

1

2

3

4

0

200,000400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

2,000,000

2,200,0002,400,000

2,600,000

2,800,0003,000,000

Projected Range of Potential Annual Increase in Age-1 Equivalents

Due to Eliminating Current IPEC Entrainment Losses

Observed Year-to-Year Increase in PYSL Abundance

(Expressed as Increase in Equivalent Age-1 Abundance)

O

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) River Herring

Figure 4. Observed year-to-year changes in riverwide juvenile abundance of river herring 

in response to observed year-to-year increases in riverwide post yolk-sac larval 

(PYSL) abundance. Based on all pairs of years (1974-2005) with observed 

positive change in PYSL abundance. 
45

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

0

1,000,000

2,000,000

3,000,0004,000,000

5,000,0006,000,000

7,000,0008,000,0009,000,000

10,000,000

Projected Range of Potential Annual Increase in Age-1 Equivalents

Due to Eliminating Current IPEC Entrainment Losses

Observed Year-to-Year Increase in PYSL Abundance

(Expressed as Increase in Equivalent Age-1 Abundance)

O

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) Striped Bass

Figure 5. Observed year-to-year changes in riverwide juvenile abundance of striped bass 

in response to observed year-to-year increases in riverwide post yolk-sac larval (PYSL) 

abundance. Based on all pairs of years (1974-2005) with observed positive change in 

PYSL abundance. 
46

-3

-2

-1

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1

2

3

0

5,000,000

10,000,000

15,000,000

20,000,000

25,000,000

30,000,000

35,000,000

40,000,000

Projected Range of Potential Annual Increase in Age-1 Equivalents

Due to Eliminating Current IPEC Entrainment Losses

Observed Year-to-Year Increase in PYSL Abundance

(Expressed as Increase in Equivalent Age-1 Abundance)

O

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) White Perch

Figure 6. Observed year-to-year changes in riverwide juvenile abundance of white perch 

in response to observed year-to-year increases in riverwide post yolk-sac larval (PYSL) 

abundance. Based on all pairs of years (1974-2005) with observed positive change in 

PYSL abundance. 

 
47

6. Conclusions 

The technology evaluations documented in this report and supporting appendices 

show that, of the alternative technologies examined by ENERCON, two have the 

potential to reduce I&E losses to levels comparable to the reduction that could be 

achieved through installation of the NYSEC Proposed Project: cylindrical wedgewire 

screens and aquatic filter barriers (Figure 7). Both of these technologies possess 

characteristics that minimize or eliminate the physical contact of organisms with intake 

screens, thereby reducing or eliminating the potential for injury. The other screening 

technologies evaluated would provide fish protection comparable to, or worse than, the 

protection provided by the Stations’ existing intake technology. Operational changes 

such as flow reductions, power reductions, and scheduled maintenance/refueling outages 

could reduce I&E losses to a greater extent than the existing intake technology, but would 

still not approach the reductions possible with cylindrical wedgewire screens, aquatic 

filter barriers, and the NYSDEC Proposed Project. 

Installation of the NYSDEC Proposed Project would involve extended delays due 

to the technical complexity of the project, to permitting requirements, and to likely 

litigation relating to local zoning ordinances. The feasibility of installing an aquatic filter 

barrier at the Stations is still uncertain, because significant operational and nuclear 

safety/licensing issues associated with this technology would have to be resolved prior to 

installation. However, it is assumed that cylindrical wedgewire screens could be installed 

at both Units 2 and 3 within approximately 5 years. If these screens were installed 

according to the schedule assumed in Section 4 of this report, the cumulative reductions 

in I&E losses over the remaining lifetimes of Units 2 and 3 would be far greater than the 

reduction that could be achieved through construction of the NYSDEC Proposed Project. 

It is questionable, however, whether any modifications of the existing intake 

technology would provide real and measurable increases in the abundance of any Hudson 

River fish populations. Entergy’s AEI report had previously concluded that historical 

operations of Units 2 and 3 have had no measurable effect on fish populations and 

communities in the Hudson River. Additional analyses documented in this report show 

that even if entrainment of fish larvae at Units 2 and 3 were completely eliminated, no 

measurable changes in the abundance of older, juvenile fish are likely to occur. 
48

 

Figure 7. Percent reductions in age-1 equivalent entrainment and impingement losses 

compared to the regulatory baseline, for technologies evaluated in this report. 

0

10

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90

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11

1.11.21.21.21.5

23456789

101112131415

15.5

Case Number

% reduction in Age-1 Equivalents Compared to

Regulatory Baseline

Operational changes Wedgewire Screens

Existing technology

Alternative Ristroph

screens

Aquatic filter

barrier

Closed-cycle

cooling

Entrainment

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15.5

Case Number

% reduction in Age-1 Equivalents Compared to

Regulatory Baseline

Operational changes Wedgewire Screens

Existing technology

Alternative Ristroph

screens

Aquatic filter

barrier

Closed-cycle

cooling

Impingement
49

7. References 

ASA. 2007. 2005 Year Class Report for the Hudson River Estuary monitoring program. 

ASA Analysis and Communication, Washingtonville, NY. 

Barnthouse, L. W., D. G. Heimbuch, W. Van Winkle, and J. R. Young. 2008. 

Entrainment and and Impingement at IP2 and IP3: A Biological Assessment. 

Central Hudson Gas and Electric (“CHGE”), et al. 1999. Draft Environmental Impact 

Statement Concerning the Applications to Renew New York State Pollutant Discharge 

Elimination System (“SPDES”) Permits for the Roseton 1 & 2, Bowline 1 & 2, and 

Indian Point 2 & 3 Steam Electric Generating Stations, Orange, Rockland, and 

Westchester Counties. 

U.S. Environmental Protection Agency (EPA). 2002. §316b Existing Facilities Benefits 

Case Studies, Part A: Evaluation Methods, Ch. 5. 

EPA. 2004. §316b Phase II Final Rule – Regional Case Studies, Part A: Evaluation 

Methods, Ch. 5. 

Electric Power Research Institute (“EPRI”). July 2004. Extrapolating impingement and 

entrainment losses to equivalent adults and production foregone. EPRI Report 1008471. 

EPRI. December 2005. Parameter development for equivalent adult and production 

foregone models. EPRI Report 1008832. 

French McCay, D. P., and J. J. Rowe. 2003. Habitat restoration as mitigation for lost 

production at multiple trophic levels. Marine Ecology Progress Series 264:233-247. 

Mattson, M. T., J. B. Waxman, and D. A., Watson. 1988. Reliability of impingement 

sampling designs: An example from the Indian Point Station. American Fisheries Society 

Monographs 4:161-169. 

National Oceanic and Atmospheric Administration (NOAA). 1997. Natural resource 

damage assessment guidance document: scaling compensatory restoration actions. 

Damage Assessment and Restoration Program, National Oceanic and Atmospheric 

Administration, Silver Spring, MD. 

Secor, D.H., and E.D. Houde. 1995. Temperature effects on the timing of striped bass 

egg production, larval viability, and recruitment potential in the Patuxent River 

(Chesapeake Bay). Estuaries 18:527-544. 
50

Young, J. R., W. P. Dey, S. M. Jinks, and D. T. Mosier. 2009. Survival of striped bass 

entrained into the cooling system of two Hudson River power plants. North American 

Journal of Fisheries Management. 29:1015-1034. 
ASA Analysis & Communication, Inc. 

1

APPENDIX A 

BIOLOGICAL ANALYSIS OF SELECTED 

COOLING SYSTEM ALTERNATIVES FOR 

INDIAN POINT ENERGY CENTER 

John R. Young 

ASA Analysis & Communication, Inc. 

February 2010 
ASA Analysis & Communication, Inc. 

2

LIST OF TABLES ................................................................. 4

Introduction ......................................................................... 6

Methodology ........................................................................ 8

Species selection .......................................................................... 8

Entrainment and impingement densities .................................. 11

Entrainment Density (DEsw) .............................................................. 12

Impingement Density (DIsm) ............................................................. 14

Modes of Action of Alternatives................................................. 15

Avoidance probability (A) ................................................................ 16

Exclusion probability (X).................................................................. 18

Survival probability if excluded (SX) ............................................... 18

Survival probability if not excluded (SnX) ....................................... 21

Calculation of losses and loss reduction .................................. 23

Results ............................................................................... 29

References ......................................................................... 60
ASA Analysis & Communication, Inc. 

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LIST OF FIGURES 

Figure 1 Calculations to estimate regulatory compliance (% loss reduction) and 

alternative performance (incremental loss reduction) for technology alternatives. .. 10 

Figure 2 Potential fates of organisms exposed to a cooling water intake structure. A = 

probability of avoiding the intake, X = probability of exclusion by the intake if 

encountered, SX= probability of surviving if excluded by the intake, Snx= probability 

of surviving if not excluded ...................................................................................... 17 

Figure 3 Estimated fraction of Atlantic tomcod excluded by screens as a function of 

opening size and fish length (mm). ........................................................................... 19 

Figure 4 Estimated fraction of striped bass excluded by screens as a function of opening 

size and fish length (mm). ......................................................................................... 19 

Figure 5 Estimated fraction of white perch excluded by screens as a function of opening 

size and fish length (mm). ......................................................................................... 19 

Figure 6 Estimated fraction of river herring excluded by screens as a function of opening 

size and fish length (mm). ......................................................................................... 20 

Figure 7 Estimated fraction of bay anchovy excluded by screens as a function of opening 

size and fish length (mm). ......................................................................................... 20 
ASA Analysis & Communication, Inc. 

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LIST OF TABLES 

Table 1 Size, habitat, and exploitation of Representative Important Species (RIS) for 

Indian Point Energy Center. ...................................................................................... 11

Table 2 Conversion factor (Psl) to estimate entrainment density from river standing crop. 

Life stages are egg, yolk-sac larva (YSL), post yolk-sac larva (PYSL), and juvenile.

................................................................................................................................... 13

Table 3 Correlations among BSS and FSS annual abundance in rm 34-55 across ages and 

surveys, and selected adjustment ratio for impingement analysis. ........................... 15

Table 4 Exclusion survival parameters used for IPEC alternatives analysis. A = 

asymptotic maximum survival, B = parameter for length, C = length below which 

survival is 0, D = latent survival rate ........................................................................ 21

Table 5 Impingement survival on current Ristroph screens at IPEC (from Fletcher 1990)

................................................................................................................................... 21

Table 6 Entrainment survival parameters for species entrained at IPEC. ME0 = initial 

instantaneous mortality rate, MEL = latent mortality rate, λ = latent mortality change 

parameter, α = parameter for length, β = parameter for temperature, γ = parameter 

for salinity, Tcrit = temperature at which thermal effects begin. ............................... 23

Table 7 Entrainment avoidance, exclusion, and survival parameters used for IPEC 

alternative technologies. ........................................................................................... 24

Table 8 Impingement avoidance, exclusion, and survival parameters used for IPEC 

alternative technologies. ........................................................................................... 24

Table 9 Intake technologies in place each year for cumulative analysis. ........................ 28

Table 10 Numbers entrained, entrainment losses, and equivalent age 1 losses, and mean 

percent loss reduction from regulatory baseline ( %LRE ) and mean incremental loss 

reduction ( E ILR ) for alternatives examined for IPEC Units 2 and 3. ...................... 32

Table 11 Numbers impinged, impingement losses, and equivalent age 1 losses, and mean 

percent loss reduction from regulatory baseline (%LRI ) and mean incremental loss 

reduction ( I ILR ) for alternatives examined for IPEC. ............................................. 33

Table 12 Monthly and annual total number of RIS entrained (millions) under intake 

technology alternatives for Indian Point Energy Center. .......................................... 34

Table 13 Monthly and annual total percent reduction in number of RIS entrained under 

intake technology alternatives for Indian Point Energy Center. Reduction calculated 

from regulatory baseline. .......................................................................................... 35

Table 14 Monthly and annual total number entrainment losses (millions) of RIS under 

intake technology alternatives for Indian Point Energy Center. ............................... 36

Table 15 Monthly and annual total percent reduction in entrainment losses of RIS under 

intake technology alternatives for Indian Point Energy Center. Reduction calculated 

from regulatory baseline. .......................................................................................... 37

Table 16 Monthly and annual total equivalent age 1 losses (millions) of RIS under intake 

technology alternatives for Indian Point Energy Center. .......................................... 38
ASA Analysis & Communication, Inc. 

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Table 17 Monthly and annual total percent reduction in equivalent age 1 losses of RIS 

under intake technology alternatives for Indian Point Energy Center. Reduction 

calculated from regulatory baseline. ......................................................................... 39

Table 18 Monthly and annual total number of RIS impinged under intake technology 

alternatives for Indian Point Energy Center. ............................................................. 40

Table 19 Monthly and annual total percent reduction in number of RIS impinged under 

intake technology alternatives for Indian Point Energy Center. Reduction calculated 

from regulatory baseline. .......................................................................................... 41

Table 20 Monthly and annual total impingement losses of RIS under intake technology 

alternatives for Indian Point Energy Center. ............................................................. 42

Table 21 Monthly and annual total percent reduction in impingement losses RIS under 

intake technology alternatives for Indian Point Energy Center. Reduction calculated 

from regulatory baseline. .......................................................................................... 43

Table 22 Monthly and annual total equivalent age 1 impingement losses of RIS under 

intake technology alternatives for Indian Point Energy Center. ............................... 44

Table 23 Monthly and annual total percent reduction in equivalent age 1 losses of 

impinged RIS under intake technology alternatives for Indian Point Energy Center. 

Reduction calculated from regulatory baseline. ........................................................ 45

Table 24 Average annual RIS equivalent age 1 loss (millions) lost yield (kg), and 

production forgone (kg) due to entrainment and impingement for intake technology 

alternatives for Indian Point Energy Center. ............................................................. 46

Table 25 Lost yield (kg) due to entrainment and impingement and combined for intake 

alternatives at IPEC. Direct lost yield represents commercial and recreational catch 

of exploited species. Converted lost yield calculated from production forgone of all 

RIS except striped bass converted to striped bass yield by EPA Phase III rule 

methodology. ............................................................................................................ 55

Table 26 Cumulative end of life estimates of undiscounted entrainment and impingement 

total losses, equivalent age 1 losses, and lost yield for RIS at IPEC units 2 and 3, 

2013 through 2035. Percent reduction relative to Baseline value. Savings ratio 

relative to Closed Cycle. Percent reduction and savings ratio averaged over species.

................................................................................................................................... 56

Table 27 Cumulative end of life estimates of discounted (3% per year) entrainment and 

impingement total losses, equivalent age 1 losses, and lost yield for RIS at IPEC 

units 2 and 3, 2013 through 2035. Percent reduction relative to Baseline value. 

Savings ratio relative to Closed Cycle. Percent reduction and savings ratio averaged 

over species. .............................................................................................................. 57

Table 28 Annual equivalent age 1 entrainment losses (millions) for RIS with existing 

technology at IPEC units 2 and 3. ............................................................................. 59
ASA Analysis & Communication, Inc. 

6

Introduction 

Entergy Nuclear Indian Point 2, LLC and Entergy Nuclear Indian Point 3, LLC 

(“Entergy”) retained ASA Analysis & Communications, Inc. (“ASA”) to determine the 

biological effectiveness, measured in reductions in entrainment and impingement losses, 

associated with potential alternative intake technologies considered for the Indian Point 

Entergy Center (“IPEC”) nuclear powered electric generating stations 2 and 3 

(individually, “Unit 2” and “Unit 3,” and collectively, the “Stations”). This evaluation 

was undertaken as part of Entergy’s alternative technology assessment performed 

pursuant to the New York State Department of Environmental Conservation 

(“NYSDEC”) Assistant Commissioner’s August 13, 2008 Interim Decision.1

 This report 

supports the “Biological Effectiveness of Alternative Intake Technologies for Indian 

Point Units 2 and 3” (the “Biological Report”) prepared by Lawrence W. Barnthouse of 

LWB Environmental Services, Inc., Douglas G. Heimbuch of AKRF, Inc., Mark T. 

Mattson of Normandeau Associates, Inc., and John R. Young of ASA Analysis & 

Communication, Inc. 

A suite of potential alternative technologies considered at IPEC was first evaluated by the 

engineering consultant, Enercon Services, Inc. (“ENERCON”) for technological and 

engineering feasibility. The alternative technologies further evaluated for biological 

effectiveness at IPEC were: 

 wedgewire screens with slot widths ranging from 1mm to 9 mm 

 Ristroph-type traveling screens with mesh sizes ranging from 1mm to 9mm 

 aquatic filter barriers (“AFB”) in front of the intakes 

In addition to these alternative technologies, the biological evaluation includes a 

comparison to the existing technologies (6mm x 12mm Ristroph screens operated 

continuously, with fish return systems; multi speed pumps operated to minimize cooling 

water use; and a cooling system design that permits entrainment survival) and to a closed 

cycle cooling system. 

Two separate biological evaluations of the technology alternatives are provided: an 

evaluation of regulatory compliance with performance standards2

 and an analysis of 

alternative technology performance (incremental reduction in entrainment and 

impingement losses) that would be expected for each alternative (Figure 1). For the 

regulatory compliance analysis (Figure 1 top), entrainment and impingement losses are 

compared to those that would occur if the station were built and operated according to 

defined baseline conditions: 

 

1

 As noted in Biological Effectiveness of Alternative Intake Technologies for Indian Point Units 2 and 3 

(Barnthouse et al. 2010), a 2003 draft permit issued by NYSDEC Staff proposed modifications to the 

cooling water intake structure at the Stations. These modifications include possible construction and 

operation of two large counter-flow, forced draft, plume abated hybrid cooling towers (the “NYSDEC 

Proposed Project”). 

2

 Typically NYSDEC issues renewed SPDES permits containing specified numerical performance 

standards for entrainment and impingement reductions. The minimum requirements are generally at or 

above the minimums in the now-suspended EPA Phase II §316(b) rule: 60% for entrainment and 80% for 

impingement. However, for the Stations, no numerical standards were specified. 
ASA Analysis & Communication, Inc. 

7

 Shoreline intake structure withdrawing from surface waters 

 3/8” mesh traveling screens operated as needed for debris removal 

 Full flow operation 365 days per year 

 No survival of impinged or entrained fish 

The regulatory compliance baseline loss is a hypothetical level of entrainment and 

impingement loss that does not, in most cases, describe actual historical losses. Usually 

generating stations do not operate at full flow on all days of the year, and often at least 

one plant design feature differs from the baseline condition. 

The alternative baseline was intended to more closely approximate actual impingement 

and entrainment losses that would occur at Unit 2 and Unit 3, if the existing intake 

technology had not been installed. For the alternative comparison (Figure 1 bottom), the 

alternative baseline assumes the same intake configuration and flow assumptions as the 

compliance baseline, but also incorporates estimates of the actual survival of entrained 

fish. 

For the regulatory baseline, losses are determined as: 

Ism mBaseline

m

I sBaseline

Esw wBaseline

w

E sBaseline

Loss D F

Loss D F









where LossEsBaseline = annual entrainment loss of species s under baseline conditions, DEsw

= expected density (number of organisms per unit volume of water withdrawn) of 

entrainable stages of species s in week w, FwBaseline = baseline (full flow) water 

withdrawal during week w, LossIsBaseline = annual impingement loss of species s under 

baseline conditions, DIsm = density of impingeable stages of species s in month m, and

FmBaseline = baseline (full flow) water withdrawal during month m. It is assumed that all 

organisms will die as a result of entrainment or impingement, therefore no explicit 

adjustment for survival is required. The time intervals for entrainment and impingement 

differ because the study designs to measure the densities were based on weekly sampling 

for entrainment, but quarterly sampling for impingement. 

Losses for the alternative baselines for entrainment and impingement at IPEC are 

calculated as: 

Ism IsBaseline mBaseline

m

I sBaseline

Esw EsBaseline wBaseline

w

E sBaseline

Loss D S F

Loss D S F

(1 )

(1 )

*

*

 

 





SEsBaseline = entrainment survival of species s under baseline conditions, SIsBaseline = 

impingement survival of species s under baseline conditions. Survival estimates reflect 

operation of the facility under baseline conditions. For entrainment, some survival would 

be expected at times when thermal stress was not severe and biocides were not being 

used. For impingement, long wash-to-wash durations and lack of a fish return system 
ASA Analysis & Communication, Inc. 

8

would preclude any significant level of survival, therefore the regulatory baseline and 

alternative baseline are equivalent. 

Losses under current technology are calculated similarly, with appropriate changes for 

current flows and survival: 

Ism IsCurrent mCurrent

m

I sCurrent

Esw EsCurrent wCurrent

w

E sCurrent

Loss D S F

Loss D S F

(1 )

(1 )

 

 





For the current technology and all technology alternatives, percent loss reductions (%LR) 

are calculated as: 

% 100% Baseline Tech

Tech

Baseline

Loss Loss LR

Loss

  

where LossBaseline = baseline loss3

, and LossTech = estimated losses for the technology 

being evaluated. 

The incremental loss reduction (ILR) is the additional reduction in losses beyond that 

already achieved with a less protective technology. For current technology, the less 

protective alternative for calculating ILR is the alternative baseline, i.e. losses that would 

occur under baseline conditions after adjusting for any survival that would have occurred. 

For other technologies, the loss with the current technology is the appropriate 

comparison: 

Alternative Current Alternative

Current Baseline Current

ILR Loss Loss

ILR Loss Loss

 

 * 

where LossBaseline* = baseline losses after adjustment for survival (alternative baseline) 

Methodology 

Species selection 

The biological analysis of alternatives is performed for the eight species determined in 

the original National Pollution Discharge Elimination System (“NPDES”) permit 

hearings for the Hudson River stations as Representative Important Species (“RIS”): 

striped bass, white perch, American shad, Atlantic tomcod, spottail shiner, bay anchovy, 

and two species collectively known as “river herring” (alewife and blueback herring). 

Species may be put in the designated RIS group due to a high degree of involvement with 

the intake structure or sensitivity to thermal discharges, high ecological or societal value, 

or as surrogates for other species for which impacts may be similar. Several of the 

designated RIS (alewife, blueback herring, bay anchovy, spottail shiner) are small 

 

3

 For comparison to performance standards, the regulatory baseline would typically be used. Percent 

reductions from the alternative baseline are also provided for information purposes. 
ASA Analysis & Communication, Inc. 

9

(typically no more than 6-7”), even as adults, and serve an ecological function as prey for 

larger fish species. The river herrings use the estuary as a spawning and nursery area, but 

spend their adult lives in the ocean. 
ASA Analysis & Communication, Inc.

Figure 1 Calculations to estimate regulatory compliance (% loss reduction) and alternative performance (incremental loss redualternatives. 

Regulatory Compliance 

(% Loss Reduction) 

Alternative Tech & Flow Alternative Survival 

Closed Cycle Flow Alternative Survival 

BasNo S

Baseline Tech & Flow Actual Survival 

Current Tech & Flow Actual Survival 

Los

Closed Cycle Technology (LossBaseline – LossClosed Cycle) / LossBaseline x 100%

Alternative Perform

(Incremental Loss Re

0 

Loss 

Scale 

LossClosed Cycle LossAlternative LossCurrent LossBaseline* 

Alternative Technology (LossBaseline – LossAlternative) / LossBaseline x 100%

Current Technology 

(LossBaseline – LossCurrent) / LossBaseline 

Current Technology LossBaseline* – LossCurrent 

Alternative Technology LossCurrent – LossAlternative 

Closed Cycle Technology LossCurrent – LossClosed Cycle 

Re

Altern
ASA Analysis & Communication, Inc. 

11

They are fished in the river primarily for use as bait. Bay anchovy, which consist of a 

single large coastal stock, inhabit only the brackish portions of the estuary during the 

warmer months. Spottail shiner is a small year-round resident species that inhabits 

primarily the freshwater portion of the estuary. White perch is a medium-sized (adults 

are up to about 12”) fish that is resident throughout the estuary, although it may undergo 

seasonal migrations within the estuary. Atlantic tomcod are another medium-sized 

estuarine resident species (although some venture outside the mouth of the estuary), but 

are near the southern end of their range in the Hudson. Tomcod spawn in the Hudson in 

midwinter, with the young becoming mature adults by the following winter. Both species 

undergo light recreational fishing pressure. 

Striped bass are a large (up to about 36” or larger), highly prized recreational species that 

enters the river to spawn during the spring. Young fish leave the estuary after 1 to 2 

years, although some fish remain resident in the river. Prior to the discovery of high PCB 

concentrations, adult striped bass were harvested from the Hudson commercially as a bycatch of the American shad fishery. The species is exploited commercially and 

recreationally in marine waters. 

American shad, a large (up to 30” or more) member of the herring family, also return to 

the river to spawn. Shad formerly supported a large commercial fishery on the Hudson, 

but overexploitation in marine waters has driven the stock to very low levels. Shad, like 

the river herrings, spawn near the upper end of the estuary. 

Table 1 Size, habitat, and exploitation of Representative Important Species (RIS) for Indian Point 

Energy Center. 

Species Size Habitat Exploitation 

Bay anchovy Small Marine/brackish No 

Spottail shiner Small Freshwater No 

Blueback herring Small Anadromous Primarily as bait 

Alewife Small Anadromous Primarily as bait 

White perch Medium Estuarine Light recreational 

Atlantic tomcod Medium Estuarine Light recreational 

American shad Large Anadromous Commercial 

Striped bass Large Anadromous Commercial & Recreational 

Entrainment and impingement densities 

The owners of the Hudson River generating stations have conducted biological studies 

since the 1970s to assess the status the estuary’s fish populations and measure 

involvement of the populations with the power stations4

. The Long River Survey 

 

4

 The survey descriptions provided are typical of the sampling, however, study designs have undergone 

change over the years. The actual study design for any particular year is provided in annual study reports. 
ASA Analysis & Communication, Inc. 

12

(“LRS”) measures the abundance and distribution of eggs, larvae, and early juvenile fish 

in the shoal, bottom and channel strata from the Battery (river miles (“rm”) 0) to Albany 

(rm 152). Sampling is conducted weekly in the spring and early summer, and bi-weekly 

from July through October, or later in some years. The Fall Shoal Survey (“FSS”, “Fall 

Juvenile Survey” or “FJS”) measures the abundance and distribution of juvenile and older 

fish in the same strata and regions. The FSS is conducted on alternate weeks from LRS 

sampling, beginning in July and extending through October. The Beach Seine Survey 

(“BSS”) samples beach areas along the entire estuary from July through November on 

alternate weeks. Annual reports on the results of these studies are produced and provided 

to NYSDEC, the most recent currently available being for the 2007 program (ASA 

2009). 

Entrainment abundance sampling to estimate the density (number per unit volume) of 

entrained organisms, was conducted at IPEC beginning in the early 1970s. However the 

most intense, and most recent, sampling was conducted from 1983-1987. Sampling was 

conducted nearly continuously from early May to early August in those years by 

pumping water from the discharge canal into nets suspended in a barrel of water. To 

assess involvement of Atlantic tomcod, sampling was conducted one day per week from 

January through April in 1987. Numerous ancillary studies were also conducted to 

provide additional information on sampling efficiency and distribution of organisms (EA 

1984, EA 1985, NAI 1987a, NAI 1987b, NAI 1988). 

Studies to estimate the fraction of organisms that survive entrainment were conducted at 

IPEC during the 1970s and 1980s. At the time the studies were begun, the methodology 

for entrainment survival was undergoing a rapid evolution but stabilized by the late 

1970s. The results of the 1979, 1980, and 1988 programs were reanalyzed and 

summarized by Young et al. (2009). 

Impingement at IPEC was sampled daily from 1973 through mid-1981, and according to 

a stratified random sampling design (Mattson et al. 1988) until the end of 1990 when the 

Ristroph screen installation was completed. No impingement sampling has been 

conducted recently. Entrainment survival on the Ristroph screens was estimated from 

on-site studies (Fletcher 1990). 

Data from these river and in-plant sampling programs were used to estimate the 

entrainment and impingement effects that would have been expected for various 

technology alternatives, had they been in place during 2001-2007. 

Entrainment Density (DEsw) 

The week-specific entrainment densities (DEsw), number of organisms per million m3

 of 

water withdrawn, were estimated by establishing the relationship between average 

weekly entrainment density in 1983-1987 (the most recent in-plant sampling data 

available) and standing crop (number of individuals) of the species in the vicinity of 
ASA Analysis & Communication, Inc. 

13

IPEC, between rm 34 and 55, in the same weeks based on LRS data from the same set of 

years. Because both the entrainment densities and river standing crops are measured with 

sampling error, a geometric mean regression (Ricker 1975) through the origin was used 

to estimate the relationship between river abundance and entrainment: 

' "

"

'

/ sl sl sl

Rslw sl Eslw

Eslw sl Rslw

P P P

C P D

D P C







where DEslw = entrainment density (# per million m3

) of life stage l of species s in week 

w, CRslw = standing crop (millions) of life stage l of species s in the river (rm 34-55) in 

week w, P’sl = regression coefficient for density regressed on standing crop, P”sl = 

regression coefficient for standing crop regressed on density; Psl = conversion factor for 

life stage l of species s. 

This technique did not work for bay anchovy juveniles and American shad eggs because, 

due to low densities and sampling variation, they were not found in both entrainment and 

river sampling in the same week. For bay anchovy juveniles, FSS data were substituted 

for LRS data. For American shad eggs, Psl was defined as the ratio of mean entrainment 

density and mean river standing crop. 

Table 2 Conversion factor (Psl) to estimate entrainment density from river standing crop. Life 

stages are egg, yolk-sac larva (YSL), post yolk-sac larva (PYSL), and juvenile. 

Species Psl

Egg YSL PYSL Juvenile

Bay anchovy 382 35,422 759 112 

American shad 11,651 58 4,501 423 

Striped bass 91 264 1,257 3,407 

Atlantic tomcod No data No data 4.2 383 

White perch 495 86 643 4,356 

River herrings 

(alewife & 

blueback herring) 

5,572 8,976 1,557 2,224 

The conversion factors (Table 2) were then applied to the weekly LRS standing crops 

(FSS standing crops for bay anchovy juveniles) observed in 2001-2007 sampling to 

estimate 2001-2007 entrainment densities. Using this method, entrainment density can 

be estimated for any week in which there was river sampling between rm 34 and 55. For 

weeks between the beginning and end of the sampling program, standing crops in weeks 

that were not sampled were estimated by linear interpolation. 

Swimming and physiological capabilities increase as fish develop from the newly 

hatched prolarvae to juvenile and older stages (Beamish 1978, Yin and Blaxter 1987). In 

addition, development is a continual process and classification into life stage may be 

somewhat subjective (Lagler et al. 1962). Therefore the changes that occur in avoidance, 
ASA Analysis & Communication, Inc. 

14

exclusion, and survival probabilities may be more closely related to size than to the 

developmental stage. To account more accurately for these size-related effects, the life 

stage densities were converted to length-specific densities based on length frequencies of 

entrained individuals during 1983-1987: 

 

l

EslLw swlLDEslw D f

where DEsLw = density (# per million m3) of species s life stage l of length L in week w, 

fswlL = fraction of species s, life stage l that are length L in week w. 

Impingement Density (DIsm) 

Impingement sampling at IPEC was conducted from 1972 through 1990, when the 

modified Ristroph screen installation was completed. Because impingement estimates 

are desired for the most recent seven years (2001-2207), the most recent seven years of 

impingement sampling (1984-1990) were selected as a basis for making the estimates. 

During those years sampling was conducted according to a stratified random sampling 

design (Mattson et al. 1988). In order to estimate recent impingement densities, it is 

necessary to use the historical impingement data, adjusted for changes in abundance from 

the time those data were collected to the recent period using data collected in the Hudson 

River Estuary Monitoring Program: 

(1984 1990)

(2001 2007)

(1984 1990)



  

Rs

Rs

Ism Ism A

A D D

where DIsm(19841990) = mean impingement density in month m of species s during 1984-

1990, adjusted for collection efficiency; ARs(19841990) = mean standing crop in rm 34-55 of 

species s during weeks 33-40 of 1984-1990; ARs(20012007) = mean standing crop in rm 34-

55 of species s during weeks 33-40 of 2001-2007. 

DIsm(19841990) is calculated from the seasonal mean density in each year adjusted for 

collection efficiency, averaged over the years 1984-1990, and applied to each month 

within a season. 

Both the FSS and BSS data were examined as potential sources of the values of ĀRs. 

Mean annual standing crops in rm 33-55 over weeks 33-40 were calculated for young-ofyear and yearling fish for each survey. Correlations across age classes and surveys (and 

yearlings with young-of-year during the previous year) were examined to validate the 

mean standing crops as actual measures of abundance and choose the appropriate metric 

for adjustment of the historical impingement density (Table 3). 
ASA Analysis & Communication, Inc. 

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Table 3 Correlations among BSS and FSS annual abundance in rm 34-55 across ages and surveys, 

and selected adjustment ratio for impingement analysis. 

Species 

Abundance Correlations Selected Adjustment YOYBSS with YOYFSS with 

YRLBSS

YRLBSS 

(t+1)

YOYFSS YRLFSS

YRLFSS 

(t+1)

Data set 

(1984 1990)

(2001 2007)





Rs

Rs

A

A

Alewife -0.027 0.629* 0.221 0.092 -0.262 YOYBSS 3.341 

Bay anchovy -0.225 0.224 0.070 0.566* 0.149 YOYFSS 

YRLFSS

0.395 

0.109 

American 

shad - - 0.698* 0.042 0.596* YOYFSS 0.108 

Blueback 

herring -0.201 0.194 0.640** -0.179 0.558* YOYFSS 0.286 

Spottail 

shiner 0.009 0.158 - - - YOYBSS 

YRLBSS

0.629 

0.484 

Striped bass -0.361 0.369 0.018 0.894** 0.248 YOYBSS 

YRLBSS

1.141 

1.757 

Atlantic 

tomcod 0.215 0.528 0.601* 0.471 0.658* YOYFSS 0.091 

White perch 0.317 0.532 0.623** 0.770** 0.333 YOYBSS 

YRLBSS

0.630 

0.389 

* indicates p < 0.05 ** indicates p < 0.01 

Modes of Action of Alternatives 

Alternatives technologies considered for cooling water intakes generally can be separated 

into four modes of action. Technologies may induce fish to avoid the intake structure, for 

instance by providing a flight-inducing stimulus such as flashing lights or sound. If 

intake velocities are low enough, normal behavioral responses may be sufficient to 

produce avoidance. Other technologies may physically exclude fish from the intake by 

drawing water through a straining system with openings smaller than the organisms to be 

excluded. Exclusion systems may be placed away from the actual intake structure, e.g. 

wedgewire screens or barrier nets, or within the intake, e.g. fine-mesh traveling screens. 

If the “strainer” is placed within the intake a collection and return system need to be 

incorporated to achieve any reductions in losses. Other technologies may increase the 

survival of fish that encounter the intake, in contrast to a baseline of 100% mortality for 

impinged or entrained fish. 

For all three of these modes of action, it is assumed that the actual number of fish 

encountering the intake is directly proportional to the amount of cooling water flow. 

Thus, the fourth mode of action is to reduce the amount of water drawn into the intake. 

There may be interactions among these modes. For instance reduced flow rates, which 

reduce numbers of organisms impinged and potentially increase avoidance and survival 

of impinged fish, may decrease the survival of entrained fish due to higher exposure 

temperatures. 
ASA Analysis & Communication, Inc. 

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These four modes of action produce five possible fates of the organisms exposed to the 

intake. They may be (1) able to avoid the intake, (2) be physically excluded (impinged) 

at or within the intake and be returned to the source water alive, (3) be physically 

excluded (impinged) at or within the intake but not survive, (4) pass through the cooling 

system and survive, or (5) pass through the cooling system but not survive (Figure 2). 

The efficacy of the alternative technologies considered for the Stations can be divided 

into components due to avoidance, exclusion, and survival, whether excluded or not 

excluded (Figure 2): AsLAlt = probability that length L of species s can avoid the intake 

for the technology; XsLAlt = probability that length L of species s will be excluded from 

the intake for the technology; and SXsLAlt = probability that excluded length L of species s

will survive. The following sections describe the calculations for the avoidance and 

exclusion probabilities (AEsAlt, AIsAlt, XEsAlt, XIsAlt) and the survival probabilities (SEsAlt,

SIsAlt). 

Avoidance probability (A) 

Avoidance of an intake requires that an organism has a capability of swimming faster 

than the velocity of flow into the intake, is able to perceive some stimulus that triggers a 

response, and has a behavioral response appropriate to result in escape. Fish eggs have 

none of these requirements, but as newly hatched larvae develop, they increase the 

capability for all three requirements. Due to the low design through-slot velocities (0.16 

m/sec), and ambient currents that will occur at times of tidal flow in the estuary, 

entrainable stages should be capable of some avoidance of the wedgewire screens. As 

documented in Appendix B, an avoidance probability was calculated from previous 

studies of wedgewire screen performance (Heuer and Tomaljanovich 1978, Weisberg et 

al. 1987, EPRI 2003). Avoidance probability was estimated by: 

 AsLAlt = 1 – exp(-0.275[L-4]) 

where L = length in mm. 

This function predicts no avoidance for larvae 4 mm or less, 24% avoidance for 5-mm 

larvae, 50% avoidance by 6.5 mm, and 95% avoidance at 15 mm fish. 

The AFB being considered will have enough filtering area that through-fabric velocities 

will be low enough that larval life stages should be able to avoid impingement, and even 

eggs and larvae that may contact the barrier should not be harmed. However, in practice 

it is difficult to maintain a perfect seal around the intake so that all water withdrawn must 

pass through the barrier (Appendix B). It was assumed that the barrier would be 79% 

effective in straining the water withdrawn, and that only 21% of the water would be 

unfiltered. 
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Figure 2 Potential fates of organisms exposed to a cooling water intake structure. Only organisms in 

the Excluded-Dead and Passed-Dead fates are included in the loss estimates. 
ASA Analysis & Communication, Inc. 

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Due to the designs considered for wedgewire screens and AFBs, the water velocity 

through the intake filtering surface will be less than 0.5 feet per second (“fps”), a velocity 

which is considered slow enough that “impingeable” sized fish can avoid impingement. 

For the AFB, it is assumed that 21% of the water withdrawn will not pass through the 

barrier but will somehow bypass it. Thus avoidance probability is 1.0 for wedgewire 

screens, 0 for fine-mesh screens, and 0.79 for AFB. 

Exclusion probability (X) 

Exclusion of organisms at the intake structure is a function of size of the mesh or slot 

width and the dimensions of the organism, which change as the organism grows. 

Exclusion probabilities for entrainment as a function of size were determined by 

measuring the body depth and width of specimens of the RIS over the range of sizes that 

are subject to entrainment (See Appendix B). The exclusion probabilities described 

approximate sigmoid curves with no exclusion at the smallest sizes, and 100% exclusion 

for larger sizes. The lengths at which exclusion occurs shift upward as slot size or mesh 

size increases (Figures 3 to 7). 

The exclusion probabilities for wedgewire screens and fine-mesh screens are considered 

to be 1.0 for impingeable size fish, i.e. those that would be excluded by the conventional 

3/8” mesh traveling screen. However, for AFB, not all of the water will be filtered, 

therefore exclusion of the fish will be 1.0 in filtered water but 0 in unfiltered water. 

Survival probability if excluded (SX) 

Survival of small fish that would have been entrained under the current technology but 

are excluded from the intake by fine-mesh screens was estimated from studies conducted 

at the Danskammer Point facility in 1986 and 1988 (NAI 1988b, NAI 1989). Fine-mesh 

(3 mm) screens were installed at the Danskammer Point Unit 3 intake, and there were 

standard 3/8” mesh at Danskammer Point Unit 4. Although differences in survival 

between the two units were inconsistent, there was a clear length-related pattern to 

survival. The statistical model fit to the Danskammer data from both intakes was: 

SIsL  A[1 exp(B{Length C})]D

where SIsL = impingement survival probability for species s of length L, A = asymptotic 

maximum survival, B = parameter for length, C = length below which survival is 0, D = 

latent survival rate. 
ASA Analysis & Communication, Inc. 

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Atlantic tomcod

0

0.2

0.4

0.6

0.8

1

0 20 40 60 80

Length

Fraction Excluded

1 mm

1.5 mm

2 mm

3 mm

6 mm

9 mm

Figure 3 Estimated fraction of Atlantic tomcod excluded by screens as a function of opening size and 

fish length (mm). 

Striped bass

0

0.2

0.4

0.6

0.8

1

0 20 40 60 80

Length

Fraction Excluded

1 mm

1.5 mm

2 mm

3 mm

6 mm

9 mm

Figure 4 Estimated fraction of striped bass excluded by screens as a function of opening size and fish 

length (mm). 

White perch

0

0.2

0.4

0.6

0.8

1

0 20 40 60 80

Length

Fraction Excluded

1 mm

1.5 mm

2 mm

3 mm

6 mm

9 mm

Figure 5 Estimated fraction of white perch excluded by screens as a function of opening size and fish 

length (mm). 
ASA Analysis & Communication, Inc. 

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River herring

0

0.2

0.4

0.6

0.8

1

0 20 40 60 80

Length

Fraction Excluded

1 mm

1.5 mm

2 mm

3 mm

6 mm

9 mm

Figure 6 Estimated fraction of river herring excluded by screens as a function of opening size and 

fish length (mm). 

Bay anchovy

0

0.2

0.4

0.6

0.8

1

0 20 40 60 80

Length

Fraction Excluded

1 mm

1.5 mm

2 mm

3 mm

6 mm

9 mm

Figure 7 Estimated fraction of bay anchovy excluded by screens as a function of opening size and 

fish length (mm). 

To combine the length-specific survival model with the Stations-specific data, the 8-hour 

survival values (1 – mortality) from Fletcher (1990) were substituted for the A parameter 

estimated from the Danskammer data. For the current Ristroph screens, the latent 

survival rate was excluded from calculations because Fletcher’s estimates included data 

up to 8 hours after collection. Very little additional mortality occurred after 8 hours. 

However, for the fine-mesh screen evaluations, survival was estimated both without and 

with the D parameter (Table 4) to provide upper and lower bounds on survival of small 

fish that may be retained on the finer mesh. 
ASA Analysis & Communication, Inc. 

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Table 4 Exclusion survival parameters used for IPEC alternatives analysis. A = asymptotic 

maximum survival, B = parameter for length, C = length below which survival is 0, D = latent 

survival rate 

Species Aa B C D 

Striped bass 0.91 0.0392 11.96 0.2677 

White perch 0.86 0.0374 10.70 0.2292 

Atlantic tomcod 0.83 0.0664 5 0.6797 

American shad 0.65 0.0044 13.76 0 

Bay anchovy 0.77 0.0059 8 0 

Alewife 0.38 0.0044 13.76 0 

Blueback herring 0.74 0.0044 13.76 0 

Spottail shinerb 0.91 0.0645 5 0.6797 

 a Fletcher (1990) survival value substituted for estimate from Danskammer data 

 b Substituted data for Atlantic tomcod 

Studies to estimate impingement survival on the current Ristroph screens were conducted 

in 1986-1987 (Fletcher 1990). These studies provided empirical estimates of the fraction 

of many of the RIS that survive the experience undamaged, and can then be returned to 

the river. (Table 5). 

Table 5 Impingement survival on current Ristroph screens at the Stations (from Fletcher 1990) 

Species SIs

Striped bass 0.91 

White perch 0.86 

Atlantic tomcod 0.83 

American shad 0.65 

Bay anchovy 0.77 

Alewife 0.38 

Blueback herring 0.74 

Spottail shinerb 0.91 

Survival of fish impinged is assumed to be 1.0 for wedgewire screens and AFB since 

impingeable fish can either avoid impingement altogether, or should be able to easily 

escape from the mesh due to the low velocities at the face of the screens and sweeping 

flows. Impingement survival on fine-mesh screens should be equal to, or possibly better 

than, survival on the current screens. 

Survival probability if not excluded (SnX) 

Organisms that do not avoid the intake, and are not excluded, are entrained into the 

cooling system. Entrainment survival, for simplicity denoted as SE rather than SnX, is 

considered to be the product of the independent probabilities of surviving mechanical 

(physical contact with cooling system equipment, shear, turbulence), thermal, and 
ASA Analysis & Communication, Inc. 

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chemical stress (USEPA 2006). However, chlorination of the condenser cooling system 

at the Stations is limited by permit conditions to a maximum of 2 hours per unit per day, 

and 9 hours total per week, and actual chlorination is significantly less than permitted. 

Therefore, entrainment survival can be estimated as functions of only mechanical and 

thermal stresses: 

SEsLw = SmsLwSTsw 

where SEsLw = probability of surviving entrainment for species s, length L in week w, 

SmsLw = probability of surviving mechanical stresses for species s, length L in week w, and 

STsw = probability of surviving thermal stresses for species s in week w. 

The probability of surviving mechanical stress was estimated from survival studies 

conducted at IPEC in 1979 (EA 1980), 1980 (EA 1981), and 1988 (EA 1989). Years of 

intensive research at IPEC and other Hudson River stations (cite individual studies and 

ESEERCO work) produced many improvements in the equipment and protocols used to 

measure entrainment survival (O’Connor and Shaffer 1977, McGroddy and Wyman 

1977, Jinks et al. 1981, Muessig et al. 1988). The results of this research were 

incorporated into the 1979, 1980, and 1988 studies. The mechanical component of 

entrainment survival for striped bass, based on the 1979, 1980, and 1988 data, was 

determined to be a function of organism length and salinity, using failure time analysis 

(Young et al. 2009), which is an improved method of estimation over the methods 

previously used (Young 2009): 

} ) exp( ) 1 exp( { 0

 





msLw E EL L Hw

t S M M     

where SmsLw = probability of surviving the mechanical stress of entrainment for length L

of species s in week w, ME0 = initial instantaneous mortality rate, MEL = latent mortality 

rate, λ = latent mortality change parameter, t = time in days since entrainment, L = length 

in mm, Hw = salinity in ppt in week w, α = parameter for length, γ = parameter for 

salinity. 

Probability of surviving thermal stress, based on the field data from the same 1979, 1980, 

and 1988 studies, was estimated by Young et al. (2009) with a logistic model as: 

 )]} 1/{1 exp[log(99) ( STsd     TEd  Tcrit for TEd ≥ Tcrit

STsd = 1 for TEd < Tcrit

where STsd = probability of surviving the thermal stress of entrainment for species s on 

day d, β = thermal parameter, TEd = exposure temperature in the discharge (°C) on day d, 

and Tcrit = temperature (°C) at which thermal effects begin. Daily values of SmsLwSTsd

were averaged for each week. 

Parameters for striped bass were estimated by Young et al. (2009). Their analysis of the 

1979, 1980, and 1988 data was repeated for the other RIS species, however only white 
ASA Analysis & Communication, Inc. 

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perch and Atlantic tomcod had sufficient data demonstrating survival substantially above 

zero. Therefore, for species other than these three, parameter values were set to indicate 

no entrainment survival.. 

Table 6 Entrainment survival parameters for species entrained at IPEC. ME0 = initial instantaneous 

mortality rate, MEL = latent mortality rate, λ = latent mortality change parameter, α = parameter for 

length, β = parameter for temperature, γ = parameter for salinity, Tcrit = temperature at which 

thermal effects begin. 

Species ME0 MEL λ α β γ Tcrit

Striped bass 8.27 0.02 1.54 -1.75 -1.16 -0.20 30

White perch 38.21 208.62 -3.82 -2.76 -1.10 -0.41 30

Atlantic tomcod 0.506 0.677 -1.090 -0.343 -2.376 -0.22 25.1

Others5 50 0 0 0 0 0 30

For fish entrained into the service water system6, which provides up to 16,000 gallons per 

minute (“gpm”) at Unit 1, 30,000 gpm at Unit 2 and 36,000 gpm at Unit 3 for cooling 

equipment other than the condensers and for other uses, entrainment survival was set to 0. 

Mechanical stresses, thermal exposures and transit times in the service water system may 

be greater than in the cooling water system, and survival of organisms entrained into the 

service water system has not been studied. 

Calculation of losses and loss reduction 

If A = probability of avoiding the intake, X = probability of exclusion by the intake if it is 

encountered, SX= probability of surviving if excluded by the intake, Snx= probability of 

surviving if not excluded, and all probabilities are independent, then the probabilities of 

the five distinct fates are the products of the individual probabilities along each pathway: 

Fate Intake Structure Excluded Survive Probability

1 Avoid intake - Yes A

2 Encounter intake Yes Yes (1-A)XSX

3 Encounter intake Yes No (1-A)X(1-SX) 

4 Encounter intake No Yes (1-A)(1-X)Snx

5 Encounter intake No No (1-A)(1-X)(1-Snx) 

For any particular alternative technology, losses are calculated from the sum of the 

probabilities of fates 3 and 5: 

Ism sAlt sAlt XsAlt sAlt IsAlt mAlt

m

I sAlternative

Esw sAlt sAlt XsAlt sAlt EsAlt wAlt

w

E sAlternative

Loss D A X S X S F

Loss D A X S X S F

(1 )[ (1 ) (1 )(1 )]

(1 )[ (1 ) (1 )(1 )]

     

     





 

5

 Survival estimates were very low, therefore parameter values that estimate survival as 0 were substituted. 6

 Service water is used for cooling auxiliary equipment, screen wash water, and uses other than condenser 

cooling. Typically service water withdrawals are a small fraction of cooling water withdrawals. 
ASA Analysis & Communication, Inc. 

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where AsAlt = probability of species s avoiding the intake under the technology alternative, 

XsAlt = probability of species s being excluded from passing through the technology 

alternative, SXsAlt = probability of species s surviving exclusion by the technology 

alternative, SEsAlt = probability of species s surviving entrainment if not excluded by the 

technology alternative, SIsAlt = probability of species s surviving impingement on the 

current screen system if not excluded by the technology alternative, FwAlt and FmAlt = 

weekly or monthly flow under the alternative technology. The avoidance, exclusion, and 

survival probabilities will differ for entrainable size, i.e. pass through 3/8” mesh (Table 7) 

and impingeable size, i.e. excluded by 3/8” mesh (Table 8). Some technologies may not 

have avoidance or exclusion fates. 

Table 7 Entrainment avoidance, exclusion, and survival parameters used for IPEC alternative 

technologies. 

Technology 

Alternative 

Avoidance 

AsLAlt

Exclusion 

XsLAlt

Survival if 

Excluded 

SXsLAlt

Survival if not 

Excluded 

SEsLAlt

Wedgewire 

screens 

Increasing 

function of 

length 

Based on 

body 

dimensions 

and slot width 

1 Species and sizedependent 

Fine-mesh 

screens 

0 

Based on 

body 

dimensions 

and mesh size 

Increasing 

function of 

length (w/wo 

latent effects) 

Species and sizedependent 

Aquatic filter 

barrier 0.82 0 0 Species and sizedependent 

Closed cycle 

cooling 0 0 0 0 

Table 8 Impingement avoidance, exclusion, and survival parameters used for IPEC alternative 

technologies. 

Technology Alternative Avoidance 

AsLAlt

Exclusion 

XsLAlt

Survival 

SXsLAlt

Wedgewire screens 1 1 1 

Fine-mesh screens 0 1 SIsCurrent

Aquatic filter barrier 0.82 0 0 

Closed cycle cooling 0 0 0 

The percentage reduction in entrainment and impingement losses (%LR) for each species 

are calculated as: 

% 100%

% 100%

  

  

IsBaseline

IsBaseline IsAlternative

I sAlternative

EsBaseline

EsBaseline EsAlternative

E sAlternative

Loss

Loss Loss LR

Loss

Loss Loss LR
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Incremental loss reduction (ILR) of an alternative technology is based on the reduction in 

entrainment and impingement losses from those occurring under a less protective 

technology alternative, usually the currently employed technology, and is expressed as an 

absolute number of organisms: 

 

I sAlternative IsCurrent IsAlternative

IsCurrent IsBaseline IsCurrent

E sAkternative EsCurrent EsAlternative

EsCurrent EsBaseline EsCurrent

ILR Loss Loss

ILR Loss Loss

ILR Loss Loss

ILR Loss Loss

 

 

 

 

*

*

where LossEsBaseline* and LossIsBaseline* are entrainment and impingement losses using the 

baseline technology and operating practices, with any entrainment or impingement 

survival that would actually occur under this condition (alternative baseline). At IPEC, 

non-zero entrainment survival has been demonstrated, but impingement survival was not 

so LossIsBaseline* = LossIsBaseline.. 

Percent loss reductions (%LREsAlternative, %LRIsAlternative), and incremental loss reductions 

(ILREsAlternative, ILRIsAlternative) can be calculated for each year in which plant flow and 

organism densities are available. For purposes of estimating the average reductions 

toward compliance of a technology alternative, the percentage loss reductions are 

calculated for each of the taxa in a particular year and then averaged to produce an annual 

average percent reduction in year y: 









s

IsAlternative s IyAlternative

s

EsAlternative s EyAlternative

LR LR n

LR LR n

% % /

% % /

where ns = number of species. For entrainment, only 6 taxa are involved because spottail 

shiner are distributed upriver from IPEC and seldom entrained, and larval stages of 

blueback herring and alewife are indistinguishable and are combined into a single river 

herring taxon. 

The annual average percent reductions are averaged over the years 2001-2007 to obtain 

the expected average performance of the technology alternative: 









y

y IAlternative IyAlternative

y

y EAlternative EyAlternative

LR LR n

LR LR n

% % /

% % /

where ny = number of years. 

Summary of the incremental loss reductions was done by first averaging the ILR values 

for a species across the years, then summing over species. 
ASA Analysis & Communication, Inc. 

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







y

IsAlternative y IsAlternative

y

EsAlternative y EsAlternative

ILR ILR n

ILR ILR n

/

/









s

IAlternative IsAlternative

s

EAlternative EsAlternative

ILR ILR

ILR ILR

For a fish, involvement with a cooling water intake structure could happen at any life 

stage, i. e. egg, yolk-sac larva, post yolk-sac larva, juvenile, sub-adult, adult, although as 

fish grow their ability to avoid cooling water intakes increases. As an annual cohort 

(group of fish spawned in the same year) progresses through these stages, it becomes less 

numerous due to natural mortality from causes such as predation, disease, and starvation, 

but the individual surviving fish become larger in size and more valuable to the 

population because their probability of reproducing increases. Thus, the loss of a single 

egg is of less consequence to a population of fish than loss of a larva, and similarly the 

loss of a larva is of less consequence than loss of a juvenile, and so forth. Although the 

average probability of survival for any life stage varies with species, cohorts of fish often 

decline by one or more orders of magnitude from one stage to the next due solely to 

natural mortality. 

The actual metrics for entrainment and impingement losses, LossEs and LossIs, are often 

expressed as raw numbers of organisms summed over all life stages, but due to the 

different life stages’ wide variation in probability of surviving to reproduce, the 

significance of these totals is difficult to interpret. To facilitate an understanding of the 

significance of the losses, they can also be expressed as losses at some common age or 

stage which has a more obvious ecological or societal meaning, such as age 1, age at first 

reproduction, or age of entry into a fishery (Horst 1975, Rago 1984, EPRI 2004). This 

conversion to a common stage or age is particularly important when comparing 

alternative technologies that may have different effectiveness for different life stages. A 

technology that would save 50% of a million entrained eggs, could be less effective 

ecologically than a technology that saved 25% of a thousand impinged juveniles.7

For comparing among the various alternative technologies, it is unimportant which 

common life stage the losses are converted to as long as the losses are converted to an 

equivalent life stage that is used for all alternatives. The life stage selected for 

conversion in this analysis is age 1, i.e. 12 months old. Conversion to equivalent age-1 

fish allows I&E losses that occur at different life stages to be combined into a single 

metric that weights the losses according to the number that could, on average, have 

survived to age 1. The biological effectiveness of each alternative, using this approach, 

 

7

 Consider two brothers who each receive $1in change (25 pennies, 6 nickels, 2 dimes, and 1 quarter) to 

spend at the store. Due to holes in their pockets, when they get to the store some of their money has been 

lost. One brother has lost 8 coins, but the other brother has lost only 4. Which brother suffered the greater 

loss cannot be determined without knowing the number of each type of coin lost and their values. The 

conversion of entrainment and impingement losses to a common life stage is analogous. 
ASA Analysis & Communication, Inc. 

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reflects the net effectiveness of that alternative at reducing losses of young fish, including 

both entrainment and impingement losses. While this conversion is effective at 

equilibrating losses at different life stages within a single species, it may still encompass 

wide ecological differences when losses are summed across species. Age 1 bay anchovy 

and Atlantic tomcod are full-grown mature adults, but age 1 striped bass are only a 

fraction of their adult size and still 3-6 years from spawning. Comparing the effects of 

technologies across species that differ greatly in size, life history, and ecological niche, 

particularly if some of the species have recreational or commercial value, can be done by 

converting the losses to lost yield and production forgone. The losses of harvestable 

species are translated directly into weight of harvest the losses would have been expected 

to produce, and forage species are converted to additional lost harvest through the amount 

of biomass they would have been expected to produce, that would then be consumed by 

harvestable species, converted to harvestable biomass, and subsequently harvested (EPA 

2006, EPRI 2004, Rago 1984) 

Cumulative Analysis 

The effects of whatever technology is in place at the Stations will be realized over the 

course of the remaining life of the facility. Although Unit 2's operating license expires in 

2013, and Unit 3's license in 2015, Entergy has applied for 20-year license extensions for 

both units. If the license extensions are granted, the units will operate from present until 

end of life with a combination of the current technology, and any potential replacement 

technology installed at some time in the future. A cumulative analysis was performed to 

examine the possible cumulative effects of the current technology, wedgewire screens, 

and closed cycle alternatives using a realistic timeline for implementation over the time 

of the extended operating licenses. The technology implementation proposal for 

wedgewire screens (i.e., Unit 2 installed by 2013 and Unit 3 installed by 2015) is based 

on studies of this technology. The implementation schedule for the NYSDEC Proposed 

Project (i.e. construction complete by 2029) was derived by ENERCON, with input from 

counsel and Spectra Energy Transmission, LLC (owner of the gas pipeline that would 

require relocation to complete the project). 

For this analysis, three indicators, mean annual losses, mean annual equivalent age 1 

losses, and mean annual lost yield for each RIS taxon for entrainment and impingement, 

were applied to a 23-year time frame from 2013 to 2035, the year that a 20 -year license 

extension for Unit 3 would end. 

Three separate scenarios were considered: 1) Existing technology remains in place 

throughout the 23 year period; 2) Wedgewire screens are installed at both units, with Unit 

2 screens operational in 2013, and Unit 3 screens in 2015; 3) Existing technology remains 

in place until closed cycle cooling is eventually installed. The initial year of operation for 

closed cycle is assumed to be 2029 at both units. It is also assumed that a 1-year outage 

is required in 2028 to complete tie-in for both units. 

The three loss metrics, for the appropriate technologies for each scenario (Table 9) were 

summed over the 23 year period on an undiscounted, and discounted (3% per year) basis. 
ASA Analysis & Communication, Inc. 

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Table 9 Intake technologies in place each year for cumulative analysis. 

Year 

Technologies in place for scenario 

Existing Technology Wedgewire Screens Closed Cycle 

Unit 2 Unit 3 Unit 2 Unit 3 Unit 2 Unit 3 

2013 Existing Existing Wedgwire Existing Existing Existing 

2014 Existing Existing Wedgwire Existing Existing Existing 

2015 Existing Existing Wedgwire Wedgwire Existing Existing 

2016 Existing Existing Wedgwire Wedgwire Existing Existing 

2017 Existing Existing Wedgwire Wedgwire Existing Existing 

2018 Existing Existing Wedgwire Wedgwire Existing Existing 

2019 Existing Existing Wedgwire Wedgwire Existing Existing 

2020 Existing Existing Wedgwire Wedgwire Existing Existing 

2021 Existing Existing Wedgwire Wedgwire Existing Existing 

2022 Existing Existing Wedgwire Wedgwire Existing Existing 

2023 Existing Existing Wedgwire Wedgwire Existing Existing 

2024 Existing Existing Wedgwire Wedgwire Existing Existing 

2025 Existing Existing Wedgwire Wedgwire Existing Existing 

2026 Existing Existing Wedgwire Wedgwire Existing Existing 

2027 Existing Existing Wedgwire Wedgwire Existing Existing 

2028 Existing Existing Wedgwire Wedgwire Not online Not online 

2029 Existing Existing Wedgwire Wedgwire Closed Cycle Closed Cycle 

2030 Existing Existing Wedgwire Wedgwire Closed Cycle Closed Cycle 

2031 Existing Existing Wedgwire Wedgwire Closed Cycle Closed Cycle 

2032 Existing Existing Wedgwire Wedgwire Closed Cycle Closed Cycle 

2033 Existing Existing Wedgwire Wedgwire Closed Cycle Closed Cycle 

2034 Not online Existing Not online Wedgwire Not online Closed Cycle 

2035 Not online Existing Not online Wedgwire Not online Closed Cycle 

The percent reduction in cumulative losses from the regulatory baseline was calculated 

for each scenario. In addition, the ratio of reduced losses, from those for existing 

technology, due to wedgewire screen alternatives were compared to the reduced losses of 

the closed cycle alternative. 
ASA Analysis & Communication, Inc. 

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The percent reduction and savings ratio were averaged over the RIS taxa for each 

scenario. 

As a final step for the cumulative analysis, the sensitivity of the entrainment cumulative 

result to the wedgewire screen avoidance function and exclusion survival rate was 

examined. These two factors could potentially be highly determinative of the comparison 

between wedgewire screens and closed cycle cooling. For the sensitivity analysis, a 

series of reduced avoidance capability curves was developed (Figure 8). 

Figure 8 Avoidance capability curves used for sensitivity analysis. Curve 1 is based on the function 

derived from experimental data Avoidance = 1 - exp(-0.275[Length-4]). Curves 2 through 8 

represent alternative assumptions of lesser avoidance capability.

Three alternative assumptions were used for survival of organisms excluded by the 

wedgewire screens: 1) the assumption of 100% used in analysis of alternatives, 2) 

survival equivalent to the fine-mesh screen impingement survival curves estimated from 

the studies at Danskammer Point(Figure 9), and 3) zero survival of physically excluded 

organisms. 
ASA Analysis & Communication, Inc. 

30

Figure 9 Exclusion survival assumed for wedgewire screens for sensitivity analysis. Curves are 

based on parameters A, B, and C from Table 4. 

The combination of eight different assumptions about avoidance and three different 

exclusion survival assumption resulted in 24 alternative estimates of cumulative 

entrainment results. 

Results 

Main output summaries are provided in Tables 10 (entrainment) and 11 (impingement). 

Tables 12-17 contain the average monthly numbers entrained (12), % reduction of 

numbers (13), monthly entrainment losses (14) , % reduction of losses (15), monthly 

equivalent age 1 losses (16), and % reduction of losses (17). 

Tables 18-23 contain the average monthly numbers impinged (18), % reduction of 

numbers (19), monthly impingement losses (20) , % reduction of losses (21), monthly 

equivalent age 1 losses (22), and % reduction of losses (23). 

Table 24 presents equivalent age 1 losses, lost yield, and production forgone by for 

entrainment and impingement by species for each alternative. 

Table 25 presents lost yield estimates for each alternative. 

Table 26 presents the cumulative analysis for entrainment and impingement, using 

undiscounted totals. 
ASA Analysis & Communication, Inc. 

31

Table 27 presents the cumulative analysis for entrainment and impingement, using 

discounted totals. 

Figure 10 presents results of the sensitivity analysis for percent reduction of cumulative 

2013-2035 equivalent age 1 losses of wedgewire screen alternatives and closed cycle 

cooling. 

Table 28 presents the estimated annual 2001-2007 equivalent age 1 entrainment losses for 

the RIS with existing technology. 
ASA Analysis & Communication, Inc.

Table 10 Numbers entrained, entrainment losses, and equivalent age 1 losses, and mean percent loss reduction from regulatory base

incremental loss reduction ( E ILR ) for alternatives examined for IPEC Units 2 and 3. 

Case Alternative 

Numbers (millions) Losses (millions) Equivalent Age 1 (mill

Mean 

Mean % 

Reduced 

Mean 

Incremental 

Reduction Mean %LRE E ILR Mean %LRE E ILR 

0 Regulatory Baseline 1,219 0 0 1,224 0 0 3.270 0 0.0

0.5 Alternative Baseline 1,219 0 0 687 23.67 0 2.834 17.19 0.0

1 Existing Technology 1,139 17.38 79 646 34.74 42 2.637 33.77 0.1

1.0000 Flow Reduction 0MW Loss 1,128 18.04 11 632 35.88 14 2.597 35.68 0.0

1.1010 Flow Reduction 10MW Loss 861 37.33 278 587 45.07 58 2.174 44.72 0.4

1.2020 Flow Reduction 20MW Loss 805 41.68 334 578 47.36 68 1.997 47.8 0.61.2030 Flow Reduction 20-30MW Loss 783 43.31 356 567 48.63 78 1.895 49.63 0.71.2040 Flow Reduction 20-40MW Loss 781 43.42 358 565 48.77 80 1.881 49.85 0.7

1.5 One-unit outage 604 56.33 535 340 66.13 306 1.360 66.15 1.2

2 1-mm wedgewire screen 315 78.05 824 316 78.99 329 0.301 88.84 2.3

3 1.5-mm wedgewire screen 424 74.22 715 268 80.15 378 0.278 89.68 2.3

4 2-mm wedgewire screen 438 73.5 701 262 80.27 384 0.275 89.77 2.3

5 3-mm wedgewire screen 444 73.07 695 262 80.17 383 0.277 89.67 2.3

6 6-mm wedgewire screen 446 72.82 693 262 80.16 383 0.279 89.64 2.3

7 9-mm wedgewire screen 446 72.82 693 262 80.16 383 0.279 89.64 2.3

8 1-mm mesh Ristroph screen 618 57.89 521 898 25.18 -252 2.656 27.95 -0.0

8.5 1-mm mesh Ristroph screena 618 57.89 521 908 20.69 -262 2.974 18.12 -0.3

9 1.5mm mesh Ristroph screen 938 42.74 201 731 30.23 -85 2.562 31.46 0.0

9.5 1.5mm mesh Ristroph screena 938 42.74 201 739 25.86 -93 2.878 21.66 -0.2

10 2-mm mesh Ristroph screen 1,057 34.18 82 672 33.08 -26 2.520 33.49 0.1

10.5 2-mm mesh Ristroph screena 1,057 34.18 82 678 28.83 -33 2.833 23.76 -0.1

11 3-mm mesh Ristroph screen 1,122 25.14 17 646 34.99 0 2.499 34.93 0.1

11.5 3-mm mesh Ristroph screena 1,122 25.14 17 650 31.06 -4 2.802 25.5 -0.1

12 6-mm mesh Ristroph screen 1,139 17.38 0 646 34.74 0 2.637 33.77 0.0

12.5 6-mm mesh Ristroph screena 1,139 17.38 0 647 31.56 -2 2.756 26.94 -0.1

13 9-mm mesh Ristroph screen 1,143 7.55 -4 647 32.95 -1 2.690 31.5 -0.0

13.5 9-mm mesh Ristroph screena 1,143 7.55 -4 647 31.06 -2 2.734 26.82 -0.0

14 Aquatic Filter Barrier 239 82.64 900 134 88.02 511 0.474 90.39 2.115 Closed Cycle 35 97.53 1,104 35 97.44 611 0.095 97.56 2.5

15.5 Closed Cycleb 54 96.12 1,085 54 96.01 591 0.141 96.25 2.4

a Lower bound including latent impingement survival;, b Assumes maximum service water use 
ASA Analysis & Communication, Inc.

Table 11 Numbers impinged, impingement losses, and equivalent age 1 losses, and mean percent loss reduction from regulatory base

incremental loss reduction ( I ILR ) for alternatives examined for IPEC. 

Case Alternative 

Numbers Losses Equivalent A

Mean 

Mean % 

Reduced 

Mean 

Incremental 

Reduction Mean %LRE E ILR Mean %LRE 

0 Regulatory Baseline 669,465 0.00 0 669,465 0.00 0 484,294 0.0

0.5 Regulatory Baseline 669,465 0.00 0 669,465 0.00 0 484,294 0.0

1 Existing Technology 474,429 22.02 195,036 70,415 79.89 599,050 49,926 80.1

1.0000 Flow Reduction 0MW Loss 450,654 25.41 23,775 66,914 80.78 3,501 47,703 80.7

1.1010 Flow Reduction 10MW Loss 419,016 35.05 55,413 61,518 83.63 8,897 43,760 83.9

1.2020 Flow Reduction 20MW Loss 415,620 36.96 58,809 60,843 84.20 9,572 43,081 84.6

1.2030 Flow Reduction 20-30MW Loss 414,674 37.81 59,755 60,619 84.47 9,795 42,776 85.01.2040 Flow Reduction 20-40MW Loss 414,595 37.91 59,834 60,598 84.50 9,817 42,746 85.0

1.5 One-unit outage 366,793 48.68 107,635 52,915 87.85 17,499 35,790 90.0

2 1-mm wedgewire screen 17,829 97.35 456,600 2,598 99.34 67,816 1,824 99.33 1.5-mm wedgewire screen 17,829 97.35 456,600 2,598 99.34 67,816 1,824 99.34 2-mm wedgewire screen 17,829 97.35 456,600 2,598 99.34 67,816 1,824 99.35 3-mm wedgewire screen 17,829 97.35 456,600 2,598 99.34 67,816 1,824 99.36 6-mm wedgewire screen 17,829 97.35 456,600 2,598 99.34 67,816 1,824 99.37 9-mm wedgewire screen 17,829 97.35 456,600 2,598 99.34 67,816 1,824 99.38 1- mm mesh Ristroph screen 474,429 22.02 0 70,415 79.89 0 49,926 80.1

8.5 1- mm mesh Ristroph screena 474,429 22.02 0 70,415 79.89 0 49,926 80.1

9 1. 5mm mesh Ristroph screen 474,429 22.02 0 70,415 79.89 0 49,926 80.1

9.5 1. 5mm mesh Ristroph screena 474,429 22.02 0 70,415 79.89 0 49,926 80.1

10 2- mm mesh Ristroph screen 474,429 22.02 0 70,415 79.89 0 49,926 80.1

10.5 2- mm mesh Ristroph screena 474,429 22.02 0 70,415 79.89 0 49,926 80.1

11 3- mm mesh Ristroph screen 474,429 22.02 0 70,415 79.89 0 49,926 80.1

11.5 3- mm mesh Ristroph screena 474,429 22.02 0 70,415 79.89 0 49,926 80.1

12 6- mm mesh Ristroph screen 474,429 22.02 0 70,415 79.89 0 49,926 80.1

12.5 6- mm mesh Ristroph screena 474,429 22.02 0 70,415 79.89 0 49,926 80.1

13 9- mm mesh Ristroph screen 474,429 22.02 0 70,415 79.89 0 49,926 80.1

13.5 9- mm mesh Ristroph screena 474,429 22.02 0 70,415 79.89 0 49,926 80.1

14 Aquatic Filter Barrier 113,715 81.54 360,713 16,840 95.26 53,575 11,926 95.3

15 Closed Cycle 19,317 97.14 455,111 2,817 99.29 67,598 1,979 99.3

15.5 Closed Cycleb 29,287 95.64 445,142 4,277 98.92 66,137 3,034 98.9

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 12 Monthly and annual total number of RIS entrained (millions) under intake technology alternatives for Indian Point Energ

Number Entrained (millions) 

Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

0 Regulatory Baseline 0.0 0.0 0.1 0.5 385.6 492.0 224.0 83.8 30.0 2.5 0.0 

0.5 Alternative Baseline 0.0 0.0 0.1 0.5 385.6 492.0 224.0 83.8 30.0 2.5 0.0 

1 Existing Technology 0.0 0.0 0.0 0.3 336.1 472.5 218.1 80.8 28.9 2.3 0.0 

1.0000 Flow Reduction 0MW Loss 0.0 0.0 0.0 0.3 325.2 472.3 218.1 80.8 28.9 2.2 0.0 1.1010 Flow Reduction 10MW Loss 0.0 0.0 0.0 0.3 244.5 350.9 175.2 65.8 22.7 1.6 0.0 1.2020 Flow Reduction 20MW Loss 0.0 0.0 0.0 0.3 243.5 324.4 156.5 58.7 20.4 1.5 0.0 1.2030 Flow Reduction 20-30MW Loss 0.0 0.0 0.0 0.3 243.5 317.9 145.8 54.9 19.2 1.5 0.0 1.2040 Flow Reduction 20-40MW Loss 0.0 0.0 0.0 0.3 243.5 317.9 144.9 53.9 19.2 1.5 0.0 

1.5 One-unit outage 0.0 0.0 0.0 0.2 186.6 246.1 112.6 42.0 14.9 1.2 0.0 

2 1-mm wedgewire screen 0.0 0.0 0.0 0.1 118.6 121.1 49.5 17.4 8.2 0.6 0.0 3 1.5-mm wedgewire screen 0.0 0.0 0.0 0.1 151.4 162.9 76.9 24.0 8.5 0.6 0.0 4 2-mm wedgewire screen 0.0 0.0 0.0 0.1 154.2 172.1 77.9 24.3 8.6 0.6 0.0 5 3-mm wedgewire screen 0.0 0.0 0.0 0.1 156.6 174.9 78.4 24.4 8.7 0.6 0.0 6 6-mm wedgewire screen 0.0 0.0 0.0 0.1 158.5 175.1 78.4 24.4 8.7 0.6 0.0 7 9-mm wedgewire screen 0.0 0.0 0.0 0.1 158.5 175.1 78.4 24.4 8.7 0.6 0.0 8 1-mm mesh Ristroph screen 0.0 0.0 0.0 0.1 216.2 226.8 112.6 43.2 17.7 1.3 0.0 

8.5 1-mm mesh Ristroph screena 0.0 0.0 0.0 0.1 216.2 226.8 112.6 43.2 17.7 1.3 0.0 

9 1.5mm mesh Ristroph screen 0.0 0.0 0.0 0.1 312.7 368.5 169.3 63.0 22.9 1.6 0.0 

9.5 1.5mm mesh Ristroph screena 0.0 0.0 0.0 0.1 312.7 368.5 169.3 63.0 22.9 1.6 0.0 

10 2-mm mesh Ristroph screen 0.0 0.0 0.0 0.1 327.9 435.1 193.2 72.4 26.3 1.9 0.0 

10.5 2-mm mesh Ristroph screena 0.0 0.0 0.0 0.1 327.9 435.1 193.2 72.4 26.3 1.9 0.0 

11 3-mm mesh Ristroph screen 0.0 0.0 0.0 0.1 333.5 469.6 210.6 78.0 27.8 2.0 0.0 

11.5 3-mm mesh Ristroph screena 0.0 0.0 0.0 0.1 333.5 469.6 210.6 78.0 27.8 2.0 0.0 

12 6-mm mesh Ristroph screen 0.0 0.0 0.0 0.3 336.1 472.5 218.1 80.8 28.9 2.3 0.0 

12.5 6-mm mesh Ristroph screena 0.0 0.0 0.0 0.3 336.1 472.5 218.1 80.8 28.9 2.3 0.0 

13 9-mm mesh Ristroph screen 0.0 0.0 0.0 0.3 337.5 472.7 218.8 81.8 29.5 2.4 0.0 

13.5 9-mm mesh Ristroph screena 0.0 0.0 0.0 0.3 337.5 472.7 218.8 81.8 29.5 2.4 0.0 

14 Aquatic Filter Barrier 0.0 0.0 0.0 0.1 70.6 99.2 45.8 17.0 6.1 0.5 0.0 15 Closed Cycle 0.0 0.0 0.0 0.0 10.6 13.7 6.7 2.7 0.9 0.1 0.0 

15.5 Closed Cycleb 0.0 0.0 0.0 0.0 16.5 22.0 10.3 3.8 1.4 0.1 0.0 

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 13 Monthly and annual total percent reduction in number of RIS entrained under intake technology alternatives for Indian PReduction calculated from regulatory baseline. % Reduction of Number Entrained Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct 

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0

0.5 Alternative Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0

1 Existing Technology 0.0 0.0 0.2 1.1 10.8 2.7 1.8 0.2 0.0 0

1.0000 Flow Reduction 0MW Loss 0.0 0.0 0.3 1.3 11.3 2.7 1.8 0.2 0.0 01.1010 Flow Reduction 10MW Loss 0.0 0.0 0.3 1.3 14.7 13.8 4.9 1.0 0.3 01.2020 Flow Reduction 20MW Loss 0.0 0.0 0.3 1.3 14.7 16.2 6.2 1.3 0.4 01.2030 Flow Reduction 20-30MW Loss 0.0 0.0 0.3 1.3 14.7 16.8 7.0 1.6 0.5 01.2040 Flow Reduction 20-40MW Loss 0.0 0.0 0.3 1.3 14.7 16.8 7.1 1.6 0.5 0

1.5 One-unit outage 0.0 0.0 0.3 1.7 17.4 23.2 9.4 2.2 0.7 0

2 1-mm wedgewire screen 0.0 0.0 0.5 2.6 20.1 33.7 14.6 3.6 1.0 03 1.5-mm wedgewire screen 0.0 0.0 0.5 2.6 19.3 32.0 13.6 3.3 1.0 04 2-mm wedgewire screen 0.0 0.0 0.5 2.6 19.3 31.5 13.5 3.3 1.0 05 3-mm wedgewire screen 0.0 0.0 0.5 2.6 19.2 31.3 13.4 3.3 1.0 06 6-mm wedgewire screen 0.0 0.0 0.5 2.4 19.2 31.2 13.4 3.3 1.0 07 9-mm wedgewire screen 0.0 0.0 0.5 2.4 19.2 31.2 13.4 3.3 1.0 08 1-mm mesh Ristroph screen 0.0 0.0 0.5 2.6 16.4 23.0 11.3 2.2 0.6 0

8.5 1-mm mesh Ristroph screena 0.0 0.0 0.5 2.6 16.4 23.0 11.3 2.2 0.6 0

9 1.5mm mesh Ristroph screen 0.0 0.0 0.4 2.6 14.2 14.7 8.3 1.2 0.3 0

9.5 1.5mm mesh Ristroph screena 0.0 0.0 0.4 2.6 14.2 14.7 8.3 1.2 0.3 0

10 2-mm mesh Ristroph screen 0.0 0.0 0.3 2.5 13.8 9.8 6.2 0.6 0.2 0

10.5 2-mm mesh Ristroph screena 0.0 0.0 0.3 2.5 13.8 9.8 6.2 0.6 0.2 0

11 3-mm mesh Ristroph screen 0.0 0.0 0.3 2.4 13.6 4.4 3.5 0.3 0.1 0

11.5 3-mm mesh Ristroph screena 0.0 0.0 0.3 2.4 13.6 4.4 3.5 0.3 0.1 0

12 6-mm mesh Ristroph screen 0.0 0.0 0.2 1.1 10.8 2.7 1.8 0.2 0.0 0

12.5 6-mm mesh Ristroph screena 0.0 0.0 0.2 1.1 10.8 2.7 1.8 0.2 0.0 0

13 9-mm mesh Ristroph screen 0.0 0.0 0.2 0.8 4.3 1.5 0.4 0.1 0.0 0

13.5 9-mm mesh Ristroph screena 0.0 0.0 0.2 0.8 4.3 1.5 0.4 0.1 0.0 0

14 Aquatic Filter Barrier 0.0 0.0 0.4 2.4 22.6 36.3 14.2 3.6 1.1 015 Closed Cycle 0.0 0.0 0.5 2.6 25.2 44.0 17.0 4.3 1.3 0

15.5 Closed Cycleb 0.0 0.0 0.5 2.6 25.0 43.3 16.7 4.3 1.3 0

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 14 Monthly and annual total number entrainment losses (millions) of RIS under intake technology alternatives for Indian PoinEntrainment Losses (millions) Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct 

0 Regulatory Baseline 0.0 0.0 0.1 0.5 385.9 492.9 226.0 85.2 30.9 3

0.5 Alternative Baseline 0.0 0.0 0.0 0.3 119.1 230.3 219.2 85.0 30.6 2

1 Existing Technology 0.0 0.0 0.0 0.2 99.2 217.3 213.8 82.4 29.9 2

1.0000 Flow Reduction 0MW Loss 0.0 0.0 0.0 0.2 96.8 209.0 211.0 82.4 29.9 21.1010 Flow Reduction 10MW Loss 0.0 0.0 0.0 0.2 109.6 210.4 174.4 67.1 23.6 11.2020 Flow Reduction 20MW Loss 0.0 0.0 0.0 0.2 110.8 226.6 157.3 59.9 21.2 11.2030 Flow Reduction 20-30MW Loss 0.0 0.0 0.0 0.2 110.8 231.6 146.8 56.0 20.0 11.2040 Flow Reduction 20-40MW Loss 0.0 0.0 0.0 0.2 110.8 231.6 146.0 55.0 19.9 1

1.5 One-unit outage 0.0 0.0 0.0 0.1 58.4 112.5 109.2 42.8 15.4 1

2 1-mm wedgewire screen 0.0 0.0 0.0 0.1 85.6 123.4 74.9 23.3 8.3 03 1.5-mm wedgewire screen 0.0 0.0 0.0 0.1 59.6 99.4 75.9 24.0 8.5 04 2-mm wedgewire screen 0.0 0.0 0.0 0.1 57.6 94.3 76.5 24.3 8.6 05 3-mm wedgewire screen 0.0 0.0 0.0 0.1 57.5 94.4 76.8 24.4 8.7 06 6-mm wedgewire screen 0.0 0.0 0.0 0.1 57.5 94.4 76.8 24.4 8.7 07 9-mm wedgewire screen 0.0 0.0 0.0 0.1 57.5 94.4 76.8 24.4 8.7 08 1-mm mesh Ristroph screen 0.0 0.0 0.0 0.2 193.4 375.9 215.1 81.0 29.5 2

8.5 1-mm mesh Ristroph screena 0.0 0.0 0.0 0.3 194.0 378.6 218.8 82.9 30.3 2

9 1.5mm mesh Ristroph screen 0.0 0.0 0.0 0.2 115.5 287.1 214.3 81.4 29.7 2

9.5 1.5mm mesh Ristroph screena 0.0 0.0 0.0 0.2 116.1 289.4 217.1 82.9 30.3 2

10 2-mm mesh Ristroph screen 0.0 0.0 0.0 0.2 102.3 241.6 213.6 81.8 29.8 2

10.5 2-mm mesh Ristroph screena 0.0 0.0 0.0 0.2 102.9 243.4 215.6 82.9 30.3 2

11 3-mm mesh Ristroph screen 0.0 0.0 0.0 0.2 99.1 218.6 213.2 82.1 29.9 2

11.5 3-mm mesh Ristroph screena 0.0 0.0 0.0 0.2 99.7 219.2 214.5 82.9 30.3 2

12 6-mm mesh Ristroph screen 0.0 0.0 0.0 0.2 99.2 217.3 213.8 82.4 29.9 2

12.5 6-mm mesh Ristroph screena 0.0 0.0 0.0 0.2 99.6 217.6 214.2 82.8 30.2 2

13 9-mm mesh Ristroph screen 0.0 0.0 0.0 0.2 99.5 217.4 213.9 82.7 30.0 2

13.5 9-mm mesh Ristroph screena 0.0 0.0 0.0 0.2 99.6 217.7 214.2 82.8 30.1 2

14 Aquatic Filter Barrier 0.0 0.0 0.0 0.0 20.7 45.6 44.5 17.0 6.1 015 Closed Cycle 0.0 0.0 0.0 0.0 10.6 13.7 6.7 2.7 1.0 0

15.5 Closed Cycleb 0.0 0.0 0.0 0.0 16.5 22.0 10.4 3.9 1.4 0

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 15 Monthly and annual total percent reduction in entrainment losses of RIS under intake technology alternatives for Indian P

Reduction calculated from regulatory baseline. 

% Reduction of Entrainment Losses Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct 

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0

0.5 Alternative Baseline 0.0 0.0 0.2 0.9 9.7 12.2 0.6 0.0 0.0 0

1 Existing Technology 0.0 0.0 0.3 1.4 13.8 15.8 2.8 0.6 0.1 0

1.0000 Flow Reduction 0MW Loss 0.0 0.0 0.3 1.4 14.1 16.4 3.1 0.6 0.1 01.1010 Flow Reduction 10MW Loss 0.0 0.0 0.3 1.4 14.4 20.7 6.3 1.5 0.4 01.2020 Flow Reduction 20MW Loss 0.0 0.0 0.3 1.4 14.4 20.9 7.8 1.9 0.6 01.2030 Flow Reduction 20-30MW Loss 0.0 0.0 0.3 1.4 14.4 21.0 8.7 2.2 0.6 01.2040 Flow Reduction 20-40MW Loss 0.0 0.0 0.3 1.4 14.4 21.0 8.8 2.2 0.6 0

1.5 One-unit outage 0.0 0.0 0.3 1.8 17.7 30.3 12.0 3.0 0.9 0

2 1-mm wedgewire screen 0.0 0.0 0.3 2.0 17.9 34.7 17.9 4.5 1.3 03 1.5-mm wedgewire screen 0.0 0.0 0.3 2.0 18.5 35.4 17.9 4.4 1.3 04 2-mm wedgewire screen 0.0 0.0 0.3 2.0 18.5 35.6 17.8 4.4 1.3 05 3-mm wedgewire screen 0.0 0.0 0.3 2.0 18.5 35.5 17.8 4.4 1.3 06 6-mm wedgewire screen 0.0 0.0 0.3 2.0 18.5 35.5 17.8 4.4 1.3 07 9-mm wedgewire screen 0.0 0.0 0.3 2.0 18.5 35.5 17.8 4.4 1.3 08 1-mm mesh Ristroph screen 0.0 0.0 0.2 1.4 12.0 8.1 2.7 0.6 0.1 0

8.5 1-mm mesh Ristroph screena 0.0 0.0 0.2 1.2 10.4 7.0 1.5 0.4 0.0 0

9 1.5mm mesh Ristroph screen 0.0 0.0 0.2 1.4 13.6 11.5 2.7 0.6 0.1 0

9.5 1.5mm mesh Ristroph screena 0.0 0.0 0.2 1.2 12.0 10.4 1.6 0.4 0.0 0

10 2-mm mesh Ristroph screen 0.0 0.0 0.3 1.4 14.0 13.9 2.8 0.6 0.1 0

10.5 2-mm mesh Ristroph screena 0.0 0.0 0.2 1.2 12.4 12.9 1.7 0.4 0.0 0

11 3-mm mesh Ristroph screen 0.0 0.0 0.3 1.4 14.0 15.7 2.9 0.6 0.1 0

11.5 3-mm mesh Ristroph screena 0.0 0.0 0.3 1.2 12.4 14.8 1.9 0.4 0.0 0

12 6-mm mesh Ristroph screen 0.0 0.0 0.3 1.4 13.8 15.8 2.8 0.6 0.1 0

12.5 6-mm mesh Ristroph screena 0.0 0.0 0.3 1.4 12.6 15.0 1.9 0.4 0.1 0

13 9-mm mesh Ristroph screen 0.0 0.0 0.3 1.4 12.6 15.4 2.7 0.5 0.1 0

13.5 9-mm mesh Ristroph screena 0.0 0.0 0.3 1.4 12.4 14.7 1.8 0.4 0.1 0

14 Aquatic Filter Barrier 0.0 0.0 0.3 2.0 21.0 39.5 18.7 4.7 1.4 015 Closed Cycle 0.0 0.0 0.3 2.1 22.1 44.5 21.0 5.4 1.6 0

15.5 Closed Cycleb 0.0 0.0 0.3 2.1 21.8 43.7 20.7 5.3 1.6 0

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 16 Monthly and annual total equivalent age 1 losses (millions) of RIS under intake technology alternatives for Indian Point EnEquivalent Age 1 Losses (millions) Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct 

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.2 0.4 1.2 0.8 0.5 0

0.5 Alternative Baseline 0.0 0.0 0.0 0.0 0.1 0.2 1.1 0.8 0.4 0

1 Existing Technology 0.0 0.0 0.0 0.0 0.1 0.2 1.1 0.7 0.4 0

1.0000 Flow Reduction 0MW Loss 0.0 0.0 0.0 0.0 0.1 0.2 1.1 0.7 0.4 01.1010 Flow Reduction 10MW Loss 0.0 0.0 0.0 0.0 0.1 0.2 0.9 0.6 0.3 01.2020 Flow Reduction 20MW Loss 0.0 0.0 0.0 0.0 0.1 0.2 0.8 0.5 0.3 01.2030 Flow Reduction 20-30MW Loss 0.0 0.0 0.0 0.0 0.1 0.2 0.7 0.5 0.3 01.2040 Flow Reduction 20-40MW Loss 0.0 0.0 0.0 0.0 0.1 0.2 0.7 0.5 0.3 0

1.5 One-unit outage 0.0 0.0 0.0 0.0 0.0 0.1 0.5 0.4 0.2 0

2 1-mm wedgewire screen 0.0 0.0 0.0 0.0 0.1 0.1 0.1 0.0 0.0 03 1.5-mm wedgewire screen 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.0 04 2-mm wedgewire screen 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.0 05 3-mm wedgewire screen 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.0 06 6-mm wedgewire screen 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.0 07 9-mm wedgewire screen 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.0 08 1-mm mesh Ristroph screen 0.0 0.0 0.0 0.0 0.1 0.3 1.0 0.7 0.4 0

8.5 1-mm mesh Ristroph screena 0.0 0.0 0.0 0.0 0.1 0.3 1.1 0.8 0.4 0

9 1.5mm mesh Ristroph screen 0.0 0.0 0.0 0.0 0.1 0.3 1.0 0.7 0.4 0

9.5 1.5mm mesh Ristroph screena 0.0 0.0 0.0 0.0 0.1 0.3 1.1 0.8 0.4 0

10 2-mm mesh Ristroph screen 0.0 0.0 0.0 0.0 0.1 0.2 1.0 0.7 0.4 0

10.5 2-mm mesh Ristroph screena 0.0 0.0 0.0 0.0 0.1 0.3 1.1 0.8 0.4 0

11 3-mm mesh Ristroph screen 0.0 0.0 0.0 0.0 0.1 0.2 1.0 0.7 0.4 0

11.5 3-mm mesh Ristroph screena 0.0 0.0 0.0 0.0 0.1 0.2 1.1 0.8 0.4 0

12 6-mm mesh Ristroph screen 0.0 0.0 0.0 0.0 0.1 0.2 1.1 0.7 0.4 0

12.5 6-mm mesh Ristroph screena 0.0 0.0 0.0 0.0 0.1 0.2 1.1 0.8 0.4 0

13 9-mm mesh Ristroph screen 0.0 0.0 0.0 0.0 0.1 0.2 1.1 0.8 0.4 0

13.5 9-mm mesh Ristroph screena 0.0 0.0 0.0 0.0 0.1 0.2 1.1 0.8 0.4 0

14 Aquatic Filter Barrier 0.0 0.0 0.0 0.0 0.0 0.0 0.2 0.1 0.1 015 Closed Cycle 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0

15.5 Closed Cycleb 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 17 Monthly and annual total percent reduction in equivalent age 1 losses of RIS under intake technology alternatives for IndiaReduction calculated from regulatory baseline. % Reduction of Equivalent Age 1 Losses Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct 

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0

0.5 Alternative Baseline 0.0 0.0 0.0 0.2 4.8 9.0 1.2 0.5 0.7 0

1 Existing Technology 0.0 0.0 0.0 0.4 6.1 14.3 6.4 4.1 1.3 1

1.0000 Flow Reduction 0MW Loss 0.0 0.0 0.0 0.4 6.3 14.9 7.3 4.2 1.4 11.1010 Flow Reduction 10MW Loss 0.0 0.0 0.0 0.4 6.5 17.1 10.2 6.0 2.3 21.2020 Flow Reduction 20MW Loss 0.0 0.0 0.0 0.4 6.5 17.2 11.8 7.0 2.7 21.2030 Flow Reduction 20-30MW Loss 0.0 0.0 0.0 0.4 6.5 17.2 12.9 7.5 2.9 21.2040 Flow Reduction 20-40MW Loss 0.0 0.0 0.0 0.4 6.5 17.2 13.0 7.6 2.9 2

1.5 One-unit outage 0.0 0.0 0.0 0.5 8.3 24.0 17.1 9.4 3.9 3

2 1-mm wedgewire screen 0.0 0.0 0.0 0.5 7.9 27.7 26.6 14.8 6.4 43 1.5-mm wedgewire screen 0.0 0.0 0.0 0.5 8.3 28.2 26.6 14.8 6.4 44 2-mm wedgewire screen 0.0 0.0 0.0 0.5 8.3 28.3 26.5 14.8 6.4 45 3-mm wedgewire screen 0.0 0.0 0.0 0.5 8.3 28.2 26.5 14.8 6.4 46 6-mm wedgewire screen 0.0 0.0 0.0 0.5 8.3 28.2 26.5 14.8 6.4 47 9-mm wedgewire screen 0.0 0.0 0.0 0.5 8.3 28.2 26.5 14.8 6.4 48 1-mm mesh Ristroph screen 0.0 0.0 0.0 0.4 4.8 8.7 6.9 4.8 1.5 1

8.5 1-mm mesh Ristroph screena 0.0 0.0 0.0 0.3 4.4 6.9 3.5 2.3 0.5 0

9 1.5mm mesh Ristroph screen 0.0 0.0 0.0 0.4 5.9 11.0 6.9 4.8 1.5 1

9.5 1.5mm mesh Ristroph screena 0.0 0.0 0.0 0.3 5.5 9.2 3.6 2.3 0.5 0

10 2-mm mesh Ristroph screen 0.0 0.0 0.0 0.4 6.1 12.8 7.0 4.8 1.5 1

10.5 2-mm mesh Ristroph screena 0.0 0.0 0.0 0.3 5.8 11.0 3.6 2.3 0.5 0

11 3-mm mesh Ristroph screen 0.0 0.0 0.0 0.4 6.2 14.1 7.0 4.8 1.5 1

11.5 3-mm mesh Ristroph screena 0.0 0.0 0.0 0.3 5.8 12.4 3.8 2.3 0.5 0

12 6-mm mesh Ristroph screen 0.0 0.0 0.0 0.4 6.1 14.3 6.4 4.1 1.3 1

12.5 6-mm mesh Ristroph screena 0.0 0.0 0.0 0.3 5.9 12.8 4.1 2.3 0.7 0

13 9-mm mesh Ristroph screen 0.0 0.0 0.0 0.3 5.9 13.6 5.8 3.4 1.3 1

13.5 9-mm mesh Ristroph screena 0.0 0.0 0.0 0.3 5.8 12.4 4.0 2.3 1.0 0

14 Aquatic Filter Barrier 0.0 0.0 0.0 0.5 9.9 30.2 25.1 13.8 6.0 415 Closed Cycle 0.0 0.0 0.0 0.5 10.6 33.3 27.1 14.8 6.4 4

15.5 Closed Cycleb 0.0 0.0 0.0 0.5 10.4 32.8 26.8 14.6 6.3 4

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 18 Monthly and annual total number of RIS impinged under intake technology alternatives for Indian Point Energy Center. 

Number Impinged 

Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov De

0 Regulatory Baseline 139,769 130,752 139,769 19,179 19,818 19,171 5,256 5,248 5,078 62,483 60,467 62,41 Existing Technology 94,241 79,238 85,543 12,141 15,461 18,478 5,124 5,108 4,986 58,834 44,939 50,3

1.0000 Flow Reduction 0MW Loss 88,291 76,826 82,108 11,291 15,151 18,468 5,124 5,108 4,986 58,345 41,546 43,41.1010 Flow Reduction 10MW Loss 88,291 76,826 82,108 10,878 11,890 13,685 4,136 4,174 3,939 44,259 36,306 42,51.2020 Flow Reduction 20MW Loss 88,291 76,826 82,108 10,878 11,840 12,670 3,717 3,746 3,554 43,159 36,306 42,51.2030 Flow Reduction 20-30MW Loss 88,291 76,826 82,108 10,878 11,840 12,425 3,500 3,540 3,386 43,050 36,306 42,51.2040 Flow Reduction 20-40MW Loss 88,291 76,826 82,108 10,878 11,840 12,425 3,482 3,487 3,377 43,050 36,306 42,5

1.5 One-unit outage 73,388 61,527 69,460 8,225 9,409 9,810 3,009 3,017 2,912 45,810 37,460 42,7

2 1-mm wedgewire screen 3,530 3,282 3,587 437 492 504 162 174 161 1,984 1,730 1,73 1.5-mm wedgewire screen 3,530 3,282 3,587 437 492 504 162 174 161 1,984 1,730 1,74 2-mm wedgewire screen 3,530 3,282 3,587 437 492 504 162 174 161 1,984 1,730 1,75 3-mm wedgewire screen 3,530 3,282 3,587 437 492 504 162 174 161 1,984 1,730 1,76 6-mm wedgewire screen 3,530 3,282 3,587 437 492 504 162 174 161 1,984 1,730 1,77 9-mm wedgewire screen 3,530 3,282 3,587 437 492 504 162 174 161 1,984 1,730 1,78 1-mm mesh Ristroph screen 94,241 79,238 85,543 12,141 15,461 18,478 5,124 5,108 4,986 58,834 44,939 50,39 1.5mm mesh Ristroph screen 94,241 79,238 85,543 12,141 15,461 18,478 5,124 5,108 4,986 58,834 44,939 50,3

10 2-mm mesh Ristroph screen 94,241 79,238 85,543 12,141 15,461 18,478 5,124 5,108 4,986 58,834 44,939 50,311 3-mm mesh Ristroph screen 94,241 79,238 85,543 12,141 15,461 18,478 5,124 5,108 4,986 58,834 44,939 50,312 6-mm mesh Ristroph screen 94,241 79,238 85,543 12,141 15,461 18,478 5,124 5,108 4,986 58,834 44,939 50,313 9-mm mesh Ristroph screen 94,241 79,238 85,543 12,141 15,461 18,478 5,124 5,108 4,986 58,834 44,939 50,314 Aquatic Filter Barrier 22,579 19,233 20,798 2,895 3,635 4,279 1,205 1,211 1,175 13,922 10,804 11,915 Closed Cycle 3,930 3,643 3,917 497 530 528 163 174 162 2,025 1,823 1,9

15.5 Closed Cycleb 6,259 5,710 5,973 755 813 848 241 243 238 2,829 2,427 2,9

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 19 Monthly and annual total percent reduction in number of RIS impinged under intake technology alternatives for Indian Po

Reduction calculated from regulatory baseline. % Reduction in Number Impinged 

Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1 Existing Technology 3.3 3.7 3.9 1.8 1.1 0.2 0.2 0.2 0.1 0.8 3.6 3.3 

1.0000 Flow Reduction 0MW Loss 3.7 3.9 4.1 2.0 1.2 0.2 0.2 0.2 0.1 1.0 4.4 4.7 1.1010 Flow Reduction 10MW Loss 3.7 3.9 4.1 2.2 2.1 1.4 1.1 1.1 1.2 4.2 5.4 4.8 1.2020 Flow Reduction 20MW Loss 3.7 3.9 4.1 2.2 2.1 1.7 1.6 1.5 1.6 4.6 5.4 4.8 1.2030 Flow Reduction 20-30MW Loss 3.7 3.9 4.1 2.2 2.1 1.8 1.9 1.8 1.8 4.6 5.4 4.8 1.2040 Flow Reduction 20-40MW Loss 3.7 3.9 4.1 2.2 2.1 1.8 1.9 1.9 1.8 4.6 5.4 4.8 

1.5 One-unit outage 4.8 5.0 5.1 2.6 2.5 2.1 2.9 2.8 2.7 5.6 6.4 6.3 

2 1-mm wedgewire screen 9.6 9.0 9.6 5.2 5.4 5.2 5.0 5.0 4.8 13.0 12.6 13.1 3 1.5-mm wedgewire screen 9.6 9.0 9.6 5.2 5.4 5.2 5.0 5.0 4.8 13.0 12.6 13.1 4 2-mm wedgewire screen 9.6 9.0 9.6 5.2 5.4 5.2 5.0 5.0 4.8 13.0 12.6 13.1 5 3-mm wedgewire screen 9.6 9.0 9.6 5.2 5.4 5.2 5.0 5.0 4.8 13.0 12.6 13.1 6 6-mm wedgewire screen 9.6 9.0 9.6 5.2 5.4 5.2 5.0 5.0 4.8 13.0 12.6 13.1 7 9-mm wedgewire screen 9.6 9.0 9.6 5.2 5.4 5.2 5.0 5.0 4.8 13.0 12.6 13.1 8 1-mm mesh Ristroph screen 3.3 3.7 3.9 1.8 1.1 0.2 0.2 0.2 0.1 0.8 3.6 3.3 9 1.5mm mesh Ristroph screen 3.3 3.7 3.9 1.8 1.1 0.2 0.2 0.2 0.1 0.8 3.6 3.3 

10 2-mm mesh Ristroph screen 3.3 3.7 3.9 1.8 1.1 0.2 0.2 0.2 0.1 0.8 3.6 3.3 11 3-mm mesh Ristroph screen 3.3 3.7 3.9 1.8 1.1 0.2 0.2 0.2 0.1 0.8 3.6 3.3 12 6-mm mesh Ristroph screen 3.3 3.7 3.9 1.8 1.1 0.2 0.2 0.2 0.1 0.8 3.6 3.3 13 9-mm mesh Ristroph screen 3.3 3.7 3.9 1.8 1.1 0.2 0.2 0.2 0.1 0.8 3.6 3.3 14 Aquatic Filter Barrier 8.3 7.9 8.4 4.5 4.5 4.1 4.0 4.0 3.8 10.5 10.8 11.0 15 Closed Cycle 9.6 9.0 9.6 5.2 5.4 5.2 5.0 5.0 4.8 13.0 12.6 13.0 

15.5 Closed Cycleb 9.4 8.8 9.4 5.1 5.3 5.1 4.9 4.9 4.7 12.8 12.4 12.8 

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 20 Monthly and annual total impingement losses of RIS under intake technology alternatives for Indian Point Energy Center

Impingement Loss 

Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov De

0 Regulatory Baseline 139,769 130,752 139,769 19,179 19,818 19,171 5,256 5,248 5,078 62,483 60,467 62,41 Existing Technology 12,531 10,537 11,372 2,041 2,623 3,152 1,171 1,165 1,140 9,472 7,198 8,

1.0000 Flow Reduction 0MW Loss 11,741 10,217 10,916 1,898 2,569 3,150 1,171 1,165 1,140 9,385 6,646 6,1.1010 Flow Reduction 10MW Loss 11,741 10,217 10,916 1,831 2,010 2,325 941 950 896 7,086 5,823 6,1.2020 Flow Reduction 20MW Loss 11,741 10,217 10,916 1,831 2,002 2,147 841 848 801 6,895 5,823 6,1.2030 Flow Reduction 20-30MW Loss 11,741 10,217 10,916 1,831 2,002 2,101 783 793 758 6,874 5,823 6,1.2040 Flow Reduction 20-40MW Loss 11,741 10,217 10,916 1,831 2,002 2,101 779 779 755 6,874 5,823 6,

1.5 One-unit outage 9,740 8,166 9,218 1,334 1,531 1,583 601 604 584 7,107 5,841 6,

2 1-mm wedgewire screen 469 436 476 73 82 84 35 39 34 314 273 3 1.5-mm wedgewire screen 469 436 476 73 82 84 35 39 34 314 273 4 2-mm wedgewire screen 469 436 476 73 82 84 35 39 34 314 273 5 3-mm wedgewire screen 469 436 476 73 82 84 35 39 34 314 273 6 6-mm wedgewire screen 469 436 476 73 82 84 35 39 34 314 273 7 9-mm wedgewire screen 469 436 476 73 82 84 35 39 34 314 273 8 1-mm mesh Ristroph screen 12,531 10,537 11,372 2,041 2,623 3,152 1,171 1,165 1,140 9,472 7,198 8,9 1.5mm mesh Ristroph screen 12,531 10,537 11,372 2,041 2,623 3,152 1,171 1,165 1,140 9,472 7,198 8,

10 2-mm mesh Ristroph screen 12,531 10,537 11,372 2,041 2,623 3,152 1,171 1,165 1,140 9,472 7,198 8,11 3-mm mesh Ristroph screen 12,531 10,537 11,372 2,041 2,623 3,152 1,171 1,165 1,140 9,472 7,198 8,12 6-mm mesh Ristroph screen 12,531 10,537 11,372 2,041 2,623 3,152 1,171 1,165 1,140 9,472 7,198 8,13 9-mm mesh Ristroph screen 12,531 10,537 11,372 2,041 2,623 3,152 1,171 1,165 1,140 9,472 7,198 8,14 Aquatic Filter Barrier 3,002 2,558 2,765 486 615 729 274 275 267 2,237 1,727 1,15 Closed Cycle 522 484 521 83 89 89 35 39 35 321 290 

15.5 Closed Cycleb 833 759 794 127 138 144 55 55 52 454 391 

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 21 Monthly and annual total percent reduction in impingement losses RIS under intake technology alternatives for Indian Pocalculated from regulatory baseline. % Reduction in Impingement Loss Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1 Existing Technology 8.9 8.4 9.0 4.4 4.3 3.9 3.7 3.7 3.5 9.6 10.2 10.4 

1.0000 Flow Reduction 0MW Loss 9.0 8.5 9.0 4.5 4.4 3.9 3.7 3.7 3.5 9.7 10.4 10.8 1.1010 Flow Reduction 10MW Loss 9.0 8.5 9.0 4.5 4.6 4.3 4.0 3.9 3.8 10.6 10.7 10.8 1.2020 Flow Reduction 20MW Loss 9.0 8.5 9.0 4.5 4.6 4.3 4.1 4.1 4.0 10.7 10.7 10.8 1.2030 Flow Reduction 20-30MW Loss 9.0 8.5 9.0 4.5 4.6 4.4 4.2 4.1 4.0 10.8 10.7 10.8 1.2040 Flow Reduction 20-40MW Loss 9.0 8.5 9.0 4.5 4.6 4.4 4.2 4.2 4.0 10.8 10.7 10.8 

1.5 One-unit outage 9.2 8.6 9.2 4.7 4.8 4.6 4.5 4.5 4.3 11.1 11.0 11.4 

2 1-mm wedgewire screen 9.8 9.2 9.8 5.3 5.5 5.3 5.1 5.1 4.9 13.3 12.9 13.3 3 1.5-mm wedgewire screen 9.8 9.2 9.8 5.3 5.5 5.3 5.1 5.1 4.9 13.3 12.9 13.3 4 2-mm wedgewire screen 9.8 9.2 9.8 5.3 5.5 5.3 5.1 5.1 4.9 13.3 12.9 13.3 5 3-mm wedgewire screen 9.8 9.2 9.8 5.3 5.5 5.3 5.1 5.1 4.9 13.3 12.9 13.3 6 6-mm wedgewire screen 9.8 9.2 9.8 5.3 5.5 5.3 5.1 5.1 4.9 13.3 12.9 13.3 7 9-mm wedgewire screen 9.8 9.2 9.8 5.3 5.5 5.3 5.1 5.1 4.9 13.3 12.9 13.3 8 1-mm mesh Ristroph screen 8.9 8.4 9.0 4.4 4.3 3.9 3.7 3.7 3.5 9.6 10.2 10.4 9 1.5mm mesh Ristroph screen 8.9 8.4 9.0 4.4 4.3 3.9 3.7 3.7 3.5 9.6 10.2 10.4 

10 2-mm mesh Ristroph screen 8.9 8.4 9.0 4.4 4.3 3.9 3.7 3.7 3.5 9.6 10.2 10.4 11 3-mm mesh Ristroph screen 8.9 8.4 9.0 4.4 4.3 3.9 3.7 3.7 3.5 9.6 10.2 10.4 12 6-mm mesh Ristroph screen 8.9 8.4 9.0 4.4 4.3 3.9 3.7 3.7 3.5 9.6 10.2 10.4 13 9-mm mesh Ristroph screen 8.9 8.4 9.0 4.4 4.3 3.9 3.7 3.7 3.5 9.6 10.2 10.4 14 Aquatic Filter Barrier 9.6 9.0 9.7 5.1 5.2 5.0 4.8 4.8 4.6 12.5 12.3 12.7 15 Closed Cycle 9.8 9.2 9.8 5.3 5.5 5.3 5.1 5.1 4.9 13.3 12.9 13.3 

15.5 Closed Cycleb 9.8 9.2 9.8 5.3 5.4 5.3 5.1 5.1 4.9 13.2 12.8 13.2 

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 22 Monthly and annual total equivalent age 1 impingement losses of RIS under intake technology alternatives for Indian Poin

Equivalent Age 1 Losses 

Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

0 Regulatory Baseline 92,716 96,598 115,086 19,524 22,096 26,718 5,625 5,682 5,690 27,740 30,836 35,981 Existing Technology 8,438 7,886 9,472 2,002 2,870 4,406 1,153 1,166 1,173 3,815 3,333 4,21

1.0000 Flow Reduction 0MW Loss 7,905 7,645 9,092 1,861 2,806 4,404 1,153 1,166 1,173 3,784 3,083 3,631.1010 Flow Reduction 10MW Loss 7,905 7,645 9,092 1,800 2,189 3,234 918 944 909 2,878 2,691 3,551.2020 Flow Reduction 20MW Loss 7,905 7,645 9,092 1,800 2,178 2,973 806 830 798 2,809 2,691 3,551.2030 Flow Reduction 20-30MW Loss 7,905 7,645 9,092 1,800 2,178 2,905 721 750 732 2,802 2,691 3,551.2040 Flow Reduction 20-40MW Loss 7,905 7,645 9,092 1,800 2,178 2,905 714 728 727 2,802 2,691 3,55

1.5 One-unit outage 6,575 6,126 7,693 1,244 1,579 2,040 333 353 364 3,028 2,818 3,63

2 1-mm wedgewire screen 316 327 397 70 88 116 31 35 33 129 130 153 1.5-mm wedgewire screen 316 327 397 70 88 116 31 35 33 129 130 154 2-mm wedgewire screen 316 327 397 70 88 116 31 35 33 129 130 155 3-mm wedgewire screen 316 327 397 70 88 116 31 35 33 129 130 156 6-mm wedgewire screen 316 327 397 70 88 116 31 35 33 129 130 157 9-mm wedgewire screen 316 327 397 70 88 116 31 35 33 129 130 158 1-mm mesh Ristroph screen 8,438 7,886 9,472 2,002 2,870 4,406 1,153 1,166 1,173 3,815 3,333 4,219 1.5mm mesh Ristroph screen 8,438 7,886 9,472 2,002 2,870 4,406 1,153 1,166 1,173 3,815 3,333 4,21

10 2-mm mesh Ristroph screen 8,438 7,886 9,472 2,002 2,870 4,406 1,153 1,166 1,173 3,815 3,333 4,2111 3-mm mesh Ristroph screen 8,438 7,886 9,472 2,002 2,870 4,406 1,153 1,166 1,173 3,815 3,333 4,2112 6-mm mesh Ristroph screen 8,438 7,886 9,472 2,002 2,870 4,406 1,153 1,166 1,173 3,815 3,333 4,2113 9-mm mesh Ristroph screen 8,438 7,886 9,472 2,002 2,870 4,406 1,153 1,166 1,173 3,815 3,333 4,2114 Aquatic Filter Barrier 2,022 1,914 2,303 476 673 1,017 267 273 273 903 802 1,0015 Closed Cycle 352 362 434 82 97 122 31 35 33 132 136 16

15.5 Closed Cycleb 561 568 661 127 152 201 52 52 53 184 180 24

a Lower bound including latent impingement survival;, b Assumes maximum service water use
ASA Analysis & Communication, Inc.

Table 23 Monthly and annual total percent reduction in equivalent age 1 losses of impinged RIS under intake technology alternative

Center. Reduction calculated from regulatory baseline. % Reduction in Equivalent Age 1 Losses 

Case Alternative Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 

0 Regulatory Baseline 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 1 Existing Technology 8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 

1.0000 Flow Reduction 0MW Loss 8.8 9.6 12.0 6.7 7.4 8.5 4.0 4.2 4.4 3.9 4.7 6.5 1.1010 Flow Reduction 10MW Loss 8.8 9.6 12.0 6.7 7.9 9.7 4.3 4.4 4.7 4.4 5.0 6.5 1.2020 Flow Reduction 20MW Loss 8.8 9.6 12.0 6.7 7.9 9.9 4.4 4.5 4.8 4.4 5.0 6.5 1.2030 Flow Reduction 20-30MW Loss 8.8 9.6 12.0 6.7 7.9 10.0 4.5 4.6 4.9 4.4 5.0 6.5 1.2040 Flow Reduction 20-40MW Loss 8.8 9.6 12.0 6.7 7.9 10.0 4.5 4.7 4.9 4.4 5.0 6.5 

1.5 One-unit outage 9.0 9.8 12.2 7.6 8.8 11.3 5.2 5.1 5.6 4.4 5.1 6.7 

2 1-mm wedgewire screen 9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 3 1.5-mm wedgewire screen 9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 4 2-mm wedgewire screen 9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 5 3-mm wedgewire screen 9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 6 6-mm wedgewire screen 9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 7 9-mm wedgewire screen 9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 8 1-mm mesh Ristroph screen 8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 9 1.5mm mesh Ristroph screen 8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 

10 2-mm mesh Ristroph screen 8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 11 3-mm mesh Ristroph screen 8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 12 6-mm mesh Ristroph screen 8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 13 9-mm mesh Ristroph screen 8.7 9.6 12.0 6.6 7.4 8.5 4.0 4.2 4.4 3.8 4.6 6.3 14 Aquatic Filter Barrier 9.4 10.3 12.9 8.0 9.5 11.7 5.3 5.5 5.7 4.9 5.5 7.6 15 Closed Cycle 9.6 10.5 13.1 8.2 10.0 12.7 5.5 5.7 6.0 5.1 5.7 7.8 

15.5 Closed Cycleb 9.6 10.5 13.1 8.2 9.9 12.6 5.5 5.7 6.0 5.0 5.7 7.7 

a Lower bound including latent impingement survival;, b Assumes maximum service water use
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Table 24 Average annual RIS equivalent age 1 loss (millions) lost yield (kg), and production forgone (kg) due to entrainment an

intake technology alternatives for Indian Point Energy Center. 

Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

Regulatory Baseline 

0 Bay anchovy 2.332 0.014 2.346 0 0 0 5,628 2 5,6300 American shad 0.000 0.000 0.000 14 9 23 368 38 4050 Striped bass 0.571 0.048 0.619 213,460 25,942 239,402 660,935 50,960 711,8950 Atlantic tomcod 0.046 0.002 0.047 0 0 0 12,656 47 12,7040 White perch 0.279 0.399 0.678 153 322 475 12,301 13,048 25,3490 Alosa sp 0.042 0.021 0.062 135 32 167 8,318 621 8,9390 Total 3.270 0.484 3.754 213,762 26,306 240,068 700,206 64,716 764,922

Alternative Baseline 

0.5 Bay anchovy 2.332 0.484 2.817 0 26,306 26,306 5,628 64,716 70,3440.5 American shad 0.000 0.003 0.003 14 13 27 368 237 6050.5 Striped bass 0.247 0.000 0.247 102,547 1 102,549 285,377 25 285,4030.5 Atlantic tomcod 0.042 0.001 0.043 0 0 0 10,510 0 10,5100.5 White perch 0.171 0.003 0.174 97 1,526 1,623 7,548 2,997 10,5460.5 Alosa sp 0.042 0.402 0.444 135 325 459 8,318 13,059 21,3770.5 Total 2.834 0.894 3.728 102,793 28,171 130,964 317,749 81,035 398,785

Existing Technology 

1 Bay anchovy 2.223 0.000 2.223 0 0 0 5,373 7 5,3801 American shad 0.000 0.039 0.039 12 32 44 340 1,277 1,6161 Striped bass 0.214 0.003 0.217 88,821 0 88,821 247,082 0 247,0831 Atlantic tomcod 0.011 0.000 0.011 0 3 3 2,963 10 2,9741 White perch 0.151 0.000 0.151 83 1 85 6,649 24 6,6731 Alosa sp 0.039 0.056 0.094 125 3,114 3,239 7,761 7,783 15,5441 Total 2.637 0.098 2.735 89,042 3,149 92,191 270,168 9,102 279,270

Flow Reduction 0MW Loss 1.0000 Bay anchovy 2.220 0.001 2.222 0 0 0 5,369 0 5,3691.0000 American shad 0.000 0.003 0.003 12 1,457 1,469 339 2,859 3,199
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Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

1.0000 Striped bass 0.189 0.048 0.236 77,014 1,503 78,517 217,685 4,345 222,0301.0000 Atlantic tomcod 0.011 0.002 0.013 0 10 10 2,938 188 3,1261.0000 White perch 0.139 0.002 0.142 76 0 76 6,145 0 6,1451.0000 Alosa sp 0.038 0.038 0.076 125 31 156 7,729 1,244 8,9731.0000 Total 2.597 0.094 2.691 77,227 3,001 80,228 240,205 8,636 248,841Flow Reduction 10MW Loss 1.1010 Bay anchovy 1.770 0.000 1.770 0 2 2 4,287 9 4,2951.1010 American shad 0.000 0.000 0.000 10 1 11 263 20 2831.1010 Striped bass 0.224 0.000 0.225 90,338 0 90,338 259,234 6 259,2391.1010 Atlantic tomcod 0.009 0.035 0.044 0 28 28 2,571 1,137 3,7081.1010 White perch 0.142 0.044 0.185 79 1,452 1,531 6,235 4,133 10,3681.1010 Alosa sp 0.030 0.006 0.036 96 1,411 1,507 5,952 2,774 8,7261.1010 Total 2.175 0.085 2.260 90,522 2,895 93,417 278,542 8,077 286,619Flow Reduction 20MW Loss 1.2020 Bay anchovy 1.589 0.002 1.591 0 10 10 3,844 179 4,0241.2020 American shad 0.000 0.002 0.002 9 0 9 239 0 2391.2020 Striped bass 0.229 0.001 0.231 90,633 0 90,633 265,119 0 265,1191.2020 Atlantic tomcod 0.008 0.003 0.011 0 1,404 1,404 2,443 2,761 5,2041.2020 White perch 0.143 0.000 0.143 79 0 79 6,316 6 6,3211.2020 Alosa sp 0.027 0.044 0.071 88 1,455 1,544 5,482 4,160 9,6411.2020 Total 1.997 0.052 2.049 90,809 2,869 93,678 283,443 7,106 290,549Flow Reduction 20-30MW Loss 1.2030 Bay anchovy 1.493 0.035 1.527 0 28 28 3,608 1,129 4,7371.2030 American shad 0.000 0.043 0.043 8 1,444 1,453 228 4,103 4,3311.2030 Striped bass 0.227 0.000 0.227 88,682 2 88,684 261,962 8 261,9701.2030 Atlantic tomcod 0.008 0.000 0.008 0 1 1 2,394 19 2,4121.2030 White perch 0.142 0.001 0.143 77 0 77 6,250 0 6,2501.2030 Alosa sp 0.026 0.004 0.030 85 9 94 5,287 181 5,469
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Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

1.2030 Total 1.895 0.083 1.978 88,853 1,485 90,337 279,729 5,440 285,169Flow Reduction 20-40MW Loss 1.2040 Bay anchovy 1.480 0.003 1.482 0 1,402 1,402 3,576 2,757 6,3331.2040 American shad 0.000 0.000 0.000 8 0 8 227 5 2321.2040 Striped bass 0.226 0.002 0.228 88,330 9 88,340 261,118 175 261,2931.2040 Atlantic tomcod 0.008 0.002 0.010 0 0 0 2,389 0 2,3901.2040 White perch 0.141 0.000 0.141 77 2 79 6,232 8 6,2401.2040 Alosa sp 0.026 0.079 0.105 85 1,469 1,554 5,271 5,220 10,4911.2040 Total 1.881 0.085 1.966 88,501 2,882 91,383 278,814 8,166 286,979One-unit outage 

1.5 Bay anchovy 1.152 0.000 1.152 0 1 1 2,784 19 2,8031.5 American shad 0.000 0.001 0.001 6 0 6 176 0 1771.5 Striped bass 0.105 0.034 0.139 42,467 28 42,494 121,296 1,128 122,4241.5 Atlantic tomcod 0.006 0.043 0.048 0 1,441 1,441 1,576 4,092 5,6681.5 White perch 0.077 0.001 0.078 42 6 48 3,386 106 3,4921.5 Alosa sp 0.020 0.003 0.023 66 1,403 1,469 4,073 2,769 6,8431.5 Total 1.360 0.083 1.442 42,581 2,879 45,460 133,292 8,114 141,406

1-mm wedgewire screen 

2 Bay anchovy 0.145 0.001 0.146 0 0 0 395 0 3962 American shad 0.000 0.000 0.000 0 1 2 11 6 162 Striped bass 0.071 0.002 0.073 21,359 1,154 22,513 82,075 2,282 84,3572 Atlantic tomcod 0.000 0.000 0.000 0 0 0 48 6 532 White perch 0.081 0.030 0.111 36 24 60 3,629 994 4,6232 Alosa sp 0.005 0.003 0.007 14 6 20 1,105 116 1,2212 Total 0.301 0.036 0.337 21,408 1,186 22,594 87,262 3,404 90,666

1.5-mm wedgewire screen 

3 Bay anchovy 0.148 0.036 0.184 0 1,186 1,186 406 3,404 3,8093 American shad 0.000 0.000 0.000 0 0 1 11 7 18
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Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

3 Striped bass 0.047 0.000 0.047 14,385 0 14,385 54,238 1 54,2393 Atlantic tomcod 0.000 0.000 0.000 0 0 0 48 0 483 White perch 0.078 0.000 0.078 34 59 93 3,460 116 3,5763 Alosa sp 0.005 0.030 0.035 14 24 38 1,145 995 2,1403 Total 0.278 0.066 0.344 14,434 1,270 15,704 59,308 4,522 63,830

2-mm wedgewire screen 

4 Bay anchovy 0.150 0.000 0.150 0 0 0 410 0 4104 American shad 0.000 0.001 0.001 0 1 1 11 48 594 Striped bass 0.043 0.000 0.043 13,360 0 13,360 50,146 0 50,1464 Atlantic tomcod 0.000 0.000 0.000 0 0 0 48 0 494 White perch 0.077 0.000 0.077 34 0 34 3,437 1 3,4384 Alosa sp 0.005 0.002 0.007 14 120 135 1,162 297 1,4584 Total 0.275 0.004 0.279 13,409 122 13,531 55,214 346 55,560

3-mm wedgewire screen 

4 Bay anchovy 0.150 0.000 0.150 0 0 0 412 0 4125 American shad 0.000 0.000 0.000 0 59 59 12 116 1285 Striped bass 0.043 0.002 0.045 13,449 61 13,510 50,344 173 50,5175 Atlantic tomcod 0.000 0.000 0.000 0 0 0 49 7 565 White perch 0.078 0.000 0.078 35 0 35 3,479 0 3,4795 Alosa sp 0.005 0.001 0.007 14 1 16 1,165 49 1,2145 Total 0.277 0.004 0.280 13,499 122 13,620 55,460 346 55,805

6-mm wedgewire screen 

6 Bay anchovy 0.152 0.000 0.152 0 0 0 415 0 4156 American shad 0.000 0.000 0.000 0 0 0 12 1 126 Striped bass 0.044 0.000 0.044 13,654 0 13,654 50,801 0 50,8016 Atlantic tomcod 0.000 0.001 0.002 0 1 1 50 48 996 White perch 0.078 0.002 0.080 35 61 96 3,489 173 3,6626 Alosa sp 0.005 0.000 0.005 14 59 74 1,165 116 1,281
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Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

6 Total 0.279 0.004 0.282 13,704 121 13,825 55,932 339 56,272

9-mm wedgewire screen 

7 Bay anchovy 0.152 0.000 0.152 0 0 0 415 7 4227 American shad 0.000 0.000 0.000 0 0 0 12 0 127 Striped bass 0.044 0.000 0.044 13,666 0 13,666 50,831 0 50,8317 Atlantic tomcod 0.000 0.000 0.000 0 59 59 51 116 1677 White perch 0.078 0.000 0.078 35 0 35 3,489 0 3,4907 Alosa sp 0.005 0.002 0.007 14 61 75 1,165 174 1,3397 Total 0.279 0.002 0.281 13,716 120 13,836 55,962 298 56,260

1-mm mesh Ristroph screen 

8 Bay anchovy 2.069 0.001 2.071 0 1 1 5,015 48 5,0638 American shad 0.000 0.002 0.002 12 61 73 336 173 5098 Striped bass 0.331 0.000 0.331 122,560 0 122,560 383,052 0 383,0538 Atlantic tomcod 0.010 0.000 0.010 0 0 0 2,888 1 2,8898 White perch 0.207 0.000 0.207 110 0 110 9,138 0 9,1388 Alosa sp 0.039 0.000 0.039 125 0 125 7,748 7 7,7558 Total 2.656 0.004 2.659 122,807 63 122,870 408,177 230 408,407

1-mm mesh Ristroph screen* 

8.5 Bay anchovy 2.278 0.000 2.278 0 59 59 5,499 116 5,6158.5 American shad 0.000 0.000 0.000 13 0 13 357 0 3578.5 Striped bass 0.405 0.000 0.405 158,424 0 158,424 468,593 7 468,6008.5 Atlantic tomcod 0.021 0.000 0.021 0 0 0 5,654 0 5,6548.5 White perch 0.231 0.000 0.231 128 0 128 10,154 0 10,1558.5 Alosa sp 0.040 0.003 0.043 129 62 191 7,913 222 8,1358.5 Total 2.975 0.004 2.978 158,694 122 158,815 498,171 346 498,516

1.5mm fine-mesh screen 

9 Bay anchovy 2.072 0.000 2.072 0 0 0 5,022 1 5,0239 American shad 0.000 0.000 0.000 12 0 12 336 0 336
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Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

9 Striped bass 0.252 0.001 0.254 99,631 1 99,632 291,515 48 291,5649 Atlantic tomcod 0.010 0.002 0.012 0 61 61 2,886 173 3,0599 White perch 0.189 0.003 0.192 102 13 115 8,351 237 8,5889 Alosa sp 0.039 0.000 0.039 125 59 184 7,752 117 7,8699 Total 2.562 0.006 2.568 99,870 134 100,004 315,862 577 316,438

1.5mm mesh Ristroph screen* 

9.5 Bay anchovy 2.278 0.003 2.281 0 0 0 5,499 0 5,4999.5 American shad 0.000 0.000 0.000 13 3 16 357 11 3679.5 Striped bass 0.327 0.003 0.330 135,489 1,526 137,015 377,035 2,997 380,0329.5 Atlantic tomcod 0.021 0.000 0.021 0 0 0 5,652 7 5,6599.5 White perch 0.213 0.039 0.252 120 32 152 9,363 1,277 10,6409.5 Alosa sp 0.040 0.005 0.044 129 14 143 7,913 263 8,1779.5 Total 2.878 0.050 2.928 135,751 1,575 137,326 405,819 4,555 410,374

2-mm mesh Ristroph screen 

10 Bay anchovy 2.074 0.050 2.124 0 1,575 1,575 5,029 4,555 9,58410 American shad 0.000 0.003 0.003 12 13 25 336 237 57310 Striped bass 0.225 0.000 0.225 91,561 1 91,562 259,298 25 259,32310 Atlantic tomcod 0.010 0.001 0.012 0 0 0 2,882 0 2,88210 White perch 0.173 0.003 0.175 95 1,526 1,621 7,603 2,997 10,60010 Alosa sp 0.039 0.042 0.081 125 34 159 7,757 1,288 9,04510 Total 2.520 0.100 2.620 91,793 3,149 94,943 282,904 9,103 292,008

2-mm mesh Ristroph screen* 

10.5 Bay anchovy 2.278 0.000 2.278 0 0 0 5,499 7 5,50610.5 American shad 0.000 0.039 0.039 13 32 45 357 1,277 1,63310.5 Striped bass 0.299 0.003 0.302 127,402 0 127,402 344,748 0 344,74810.5 Atlantic tomcod 0.021 0.000 0.021 0 3 3 5,646 11 5,65710.5 White perch 0.196 0.000 0.196 113 1 114 8,593 25 8,61810.5 Alosa sp 0.040 0.056 0.095 129 3,114 3,243 7,913 7,790 15,703
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Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

10.5 Total 2.833 0.098 2.932 127,657 3,149 130,806 372,756 9,110 381,866

3-mm mesh Ristroph screen 

11 Bay anchovy 2.081 0.001 2.082 0 0 0 5,045 0 5,04511 American shad 0.000 0.003 0.003 12 1,526 1,539 338 2,997 3,33511 Striped bass 0.212 0.050 0.262 87,815 1,575 89,389 244,813 4,555 249,36811 Atlantic tomcod 0.010 0.003 0.013 0 13 13 2,876 237 3,11311 White perch 0.157 0.003 0.160 88 0 88 6,896 0 6,89611 Alosa sp 0.039 0.040 0.078 125 33 158 7,760 1,309 9,06911 Total 2.499 0.100 2.598 88,040 3,147 91,186 267,727 9,100 276,826

3-mm mesh Ristroph screen* 

11.5 Bay anchovy 2.278 0.000 2.278 0 3 3 5,499 11 5,50911.5 American shad 0.000 0.000 0.000 13 1 15 357 25 38211.5 Striped bass 0.286 0.000 0.286 123,348 0 123,348 329,348 7 329,35511.5 Atlantic tomcod 0.021 0.039 0.060 0 32 32 5,636 1,277 6,91211.5 White perch 0.177 0.050 0.227 104 1,575 1,679 7,774 4,555 12,32911.5 Alosa sp 0.040 0.007 0.047 129 1,526 1,655 7,913 2,998 10,91111.5 Total 2.802 0.097 2.899 123,594 3,137 126,731 356,526 8,873 365,399

6-mm mesh Ristroph screen 

12 Bay anchovy 2.223 0.003 2.226 0 13 13 5,373 237 5,61012 American shad 0.000 0.003 0.003 12 0 12 340 0 34012 Striped bass 0.214 0.001 0.216 88,821 0 88,821 247,082 0 247,08312 Atlantic tomcod 0.011 0.003 0.013 0 1,526 1,526 2,963 2,997 5,96112 White perch 0.151 0.000 0.151 83 0 83 6,649 7 6,65612 Alosa sp 0.039 0.050 0.089 125 1,579 1,704 7,761 4,591 12,35212 Total 2.637 0.061 2.697 89,042 3,118 92,160 270,168 7,834 278,002

6-mm mesh Ristroph screen* 

12.5 Bay anchovy 2.278 0.039 2.317 0 32 32 5,499 1,277 6,77512.5 American shad 0.000 0.050 0.050 13 1,575 1,588 357 4,555 4,912
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Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

12.5 Striped bass 0.258 0.000 0.258 109,384 3 109,387 296,822 11 296,83312.5 Atlantic tomcod 0.021 0.000 0.021 0 1 1 5,513 25 5,53812.5 White perch 0.160 0.001 0.162 91 0 91 7,060 0 7,06112.5 Alosa sp 0.040 0.006 0.046 129 13 142 7,913 245 8,15812.5 Total 2.756 0.097 2.853 109,617 1,623 111,240 323,164 6,113 329,277

9-mm mesh Ristroph screen 

13 Bay anchovy 2.254 0.003 2.257 0 1,526 1,526 5,443 2,997 8,44113 American shad 0.000 0.000 0.000 13 0 13 342 7 34913 Striped bass 0.229 0.001 0.230 95,992 3 95,995 264,220 55 264,27513 Atlantic tomcod 0.014 0.001 0.014 0 0 0 4,083 0 4,08313 White perch 0.155 0.000 0.155 86 1 87 6,818 3 6,82113 Alosa sp 0.039 0.091 0.129 125 1,606 1,731 7,765 5,832 13,59713 Total 2.690 0.095 2.785 96,217 3,136 99,353 288,671 8,894 297,566

9-mm mesh Ristroph screen* 

13.5 Bay anchovy 2.278 0.000 2.278 0 0 0 5,499 6 5,50513.5 American shad 0.000 0.000 0.000 13 0 13 357 0 35713.5 Striped bass 0.235 0.009 0.244 98,858 8 98,866 271,104 306 271,41013.5 Atlantic tomcod 0.022 0.012 0.034 0 379 379 5,957 1,093 7,05013.5 White perch 0.159 0.000 0.159 90 0 90 7,002 8 7,01013.5 Alosa sp 0.040 0.001 0.040 129 368 497 7,913 726 8,63913.5 Total 2.734 0.023 2.756 99,090 755 99,845 297,832 2,139 299,971

Aquatic Filter Barrier 

14 Bay anchovy 0.405 0.000 0.405 0 0 0 989 0 98914 American shad 0.000 0.000 0.000 1 0 1 37 0 3714 Striped bass 0.034 0.000 0.034 13,570 65 13,635 39,598 129 39,72714 Atlantic tomcod 0.001 0.000 0.001 0 0 0 173 0 17414 White perch 0.030 0.002 0.031 16 1 17 1,310 53 1,36214 Alosa sp 0.005 0.000 0.005 14 0 14 1,103 9 1,112
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Case Taxon 

Equivalent Age 1 

(millions) Lost Yield (kg) Production Forgone (kg) 

Ent Imp Total Ent Imp Total Ent Imp Total 

14 Total 0.474 0.002 0.476 13,600 67 13,667 43,210 190 43,401

Closed Cycle 

15 Bay anchovy 0.071 0.002 0.073 0 67 67 171 190 36215 American shad 0.000 0.000 0.000 0 1 1 10 13 2315 Striped bass 0.015 0.000 0.015 5,355 0 5,356 16,974 1 16,97515 Atlantic tomcod 0.000 0.000 0.000 0 0 0 120 0 12015 White perch 0.008 0.000 0.008 4 101 105 329 199 52815 Alosa sp 0.001 0.002 0.003 4 1 5 239 53 29215 Total 0.095 0.004 0.099 5,364 171 5,534 17,843 457 18,300

Closed Cycle** 

15.5 Bay anchovy 0.105 0.000 0.105 0 0 0 253 0 25315.5 American shad 0.000 0.002 0.002 1 2 3 16 80 9615.5 Striped bass 0.023 0.000 0.023 8,254 2 8,256 26,307 0 26,30715.5 Atlantic tomcod 0.001 0.000 0.001 0 38 38 183 0 18315.5 White perch 0.012 0.000 0.012 6 128 134 517 0 51715.5 Alosa sp 0.002 0.003 0.005 6 696 702 370 494 86315.5 Total 0.141 0.006 0.147 8,267 866 9,133 27,646 574 28,219

* Includes latent mortality on Ristroph screens ** Assumes full use of service water
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Table 25 Lost yield (kg) due to entrainment and impingement and combined for intake alternatives at IPEC. Direct lost yield r

and recreational catch of exploited species. Converted lost yield calculated from production forgone of all RIS except striped b

bass yield by EPA Phase III rule methodology. 

Case Alternative Baseline 

Entrainment Impingement 

Direct Converted Total Incremental Reduction Direct Converted Total Incrementa

Reduction 

0 Regulatory Baseline 213,762 1,268 215,030 0 26,306 700 27,006 0 

0.5 Alternative Baseline 102,793 1,046 103,838 111,192 26,306 700 27,006 0 

1 Current technology 6x12mm 89,042 746 89,788 125,242 1,575 79 1,654 25,352 

1.0001 Flow Reduction 0MW Loss 77,227 727 77,954 11,834 1,503 76 1,579 75 1.1010 Flow Reduction 10MW Loss 90,522 624 91,146 -1,358 1,452 69 1,522 132 1.2020 Flow Reduction 20MW Loss 90,809 592 91,400 -1,612 1,444 68 1,513 141 1.2030 Flow Reduction 20-30MW Loss 88,853 574 89,427 361 1,442 68 1,510 144 1.2040 Flow Reduction 20-40MW Loss 88,501 572 89,072 716 1,441 68 1,509 145 

1.5 One-unit outage 42,581 387 42,968 46,820 1,186 57 1,243 411 

2 1-mm wedgewire screen 21,408 168 21,576 68,212 61 3 64 1,590 3 1.5-mm wedgewire screen 14,434 164 14,598 75,190 61 3 64 1,590 4 2-mm wedgewire screen 13,409 164 13,573 76,215 61 3 64 1,590 5 3-mm wedgewire screen 13,499 165 13,664 76,124 61 3 64 1,590 6 6-mm wedgewire screen 13,704 166 13,869 75,919 61 3 64 1,590 7 9-mm wedgewire screen 13,716 166 13,882 75,906 61 3 64 1,590 8 1-mm fine-mesh screen 122,807 811 123,618 -33,830 1,575 79 1,654 0 

8.5 1-mm fine-mesh screen_LB 158,694 955 159,649 -69,861 1,575 79 1,654 0 

9 1.5mm fine-mesh screen 99,870 786 100,656 -10,868 1,575 79 1,654 0 

9.5 1.5mm fine-mesh screen_LB 135,751 930 136,681 -46,893 1,575 79 1,654 0 

10 2-mm fine-mesh screen 91,793 762 92,556 -2,768 1,575 79 1,654 0 

10.5 2-mm fine-mesh screen_LB 127,657 905 128,561 -38,773 1,575 79 1,654 0 

11 3-mm fine-mesh screen 88,040 740 88,780 1,008 1,575 79 1,654 0 

11.5 3-mm fine-mesh screen_LB 123,594 878 124,472 -34,684 1,575 79 1,654 0 

12 6-mm fine-mesh screen 89,042 746 89,788 0 1,575 79 1,654 0 

12.5 6-mm fine-mesh screen_LB 109,617 851 110,468 -20,680 1,575 79 1,654 0 

13 9-mm fine-mesh screen 96,217 790 97,006 -7,218 1,575 79 1,654 0 

13.5 9-mm fine-mesh screen_LB 99,090 863 99,953 -10,165 1,575 79 1,654 0 

14 Aquatic Filter Barrier 13,600 117 13,717 76,071 379 19 398 1,256 15 Closed Cycle 5,364 28 5,392 84,396 67 3 70 1,584 

15.5 Closed Cycle - Max SW 8,267 43 8,310 81,478 104 5 109 1,545 
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Table 26 Cumulative end of life estimates of undiscounted entrainment and impingement total losses, equivalent age 1 losses, a

IPEC units 2 and 3, 2013 through 2035. Percent reduction relative to Baseline value. Savings ratio relative to Closed Cycle. Pe

savings ratio averaged over species. 

Undiscounted

Scenario

Year

Technology

Operational

Total Losses (M) Equivalent Age 1 Losses (M) Lost Yield (kg)

Number % Reduction Savings Ratio Number % Reduction Savings Ratio Number % Reduction Sa

R

Unit 2 Unit 3

Entrainment

Regulatory Baseline 26,931 0 71.914 0 4,729,189 0Existing Technologies 2013 2013 14,183 34.87 0 57.969 34.36 0 1,972,413 33.53 1‐mm wedgewire screen 2013 2015 7,264 76.58 1.93 8.926 87.25 2.54 540,075 87.52 1.5‐mm wedgewire screen 2013 2015 6,255 77.75 2.09 8.424 88.03 2.61 393,535 88.14 2‐mm wedgewire screen 2013 2015 6,127 77.85 2.11 8.371 88.11 2.62 372,008 88.2 3‐mm wedgewire screen 2013 2015 6,136 77.75 2.1 8.408 88.03 2.62 373,925 88.11 6‐mm wedgewire screen 2013 2015 6,137 77.74 2.1 8.448 87.99 2.61 378,237 88.07 9‐mm wedgewire screen 2013 2015 6,137 77.74 2.1 8.449 87.99 2.61 378,493 88.06 Closed Cycle 2029 2029 9,885 54.85 1 40.1 54.55 1 1,377,758 53.98 

Impingement

Regulatory Baseline 14.728 0 10.654 0 594,169 0Existing Technologies 2013 2013 1.549 82.11 0 1.098 80.98 0 36,391 81.02 1‐mm wedgewire screen 2013 2015 0.125 98.62 2.99 0.088 98.56 2.99 2,991 98.55 1.5‐mm wedgewire screen 2013 2015 0.125 98.62 2.99 0.088 98.56 2.99 2,991 98.55 2‐mm wedgewire screen 2013 2015 0.125 98.62 2.99 0.088 98.56 2.99 2,991 98.55 3‐mm wedgewire screen 2013 2015 0.125 98.62 2.99 0.088 98.56 2.99 2,991 98.55 6‐mm wedgewire screen 2013 2015 0.125 98.62 2.99 0.088 98.56 2.99 2,991 98.55 9‐mm wedgewire screen 2013 2015 0.125 98.62 2.99 0.088 98.56 2.99 2,991 98.55 Closed Cycle 2029 2029 1.073 87.62 1 0.761 86.85 1 25,234 86.88 
ASA Analysis & Communication, Inc.

Table 27 Cumulative end of life estimates of discounted (3% per year) entrainment and impingement total losses, equivalent ag

for RIS at IPEC units 2 and 3, 2013 through 2035. Percent reduction relative to Baseline value. Savings ratio relative to Closed 

reduction and savings ratio averaged over species. 

Discounted 3% per year

Scenario

Year

Technology

Operational

Total Losses (M) Equivalent Age 1 Losses (M) Lost Yield (kg)

Number % Reduction Savings Ratio Number % Reduction Savings Ratio Number % Reduction Savin

Rati

Unit 2 Unit 3

Entrainment

Regulatory Baseline 19,919 0 53.189 0 3,497,765 0Existing Technologies 2013 2013 10,494 34.84 0 42.881 34.34 0 1,459,318 33.51 1‐mm wedgewire screen 2013 2015 5,456 75.91 2.43 7.176 86.41 3.2 416,421 86.68 3.1.5‐mm wedgewire screen 2013 2015 4,721 77.07 2.63 6.81 87.19 3.29 309,590 87.28 3.2‐mm wedgewire screen 2013 2015 4,627 77.17 2.65 6.771 87.27 3.3 293,906 87.34 3.3‐mm wedgewire screen 2013 2015 4,634 77.07 2.65 6.798 87.19 3.3 295,301 87.25 3.6‐mm wedgewire screen 2013 2015 4,635 77.06 2.65 6.827 87.15 3.29 298,439 87.21 3.9‐mm wedgewire screen 2013 2015 4,635 77.06 2.65 6.828 87.15 3.29 298,626 87.21 3.Closed Cycle 2029 2029 8,007 50.47 1 32.547 50.13 1 1,115,286 49.5 

Impingement

Regulatory Baseline 10.892 0 7.88 0 439,421 0Existing Technologies 2013 2013 1.146 82.11 0 0.812 80.98 0 26,913 81.02 1‐mm wedgewire screen 2013 2015 0.109 98.36 3.77 0.077 98.29 3.77 2,602 98.28 3.1.5‐mm wedgewire screen 2013 2015 0.109 98.36 3.77 0.077 98.29 3.77 2,602 98.28 3.2‐mm wedgewire screen 2013 2015 0.109 98.36 3.77 0.077 98.29 3.77 2,602 98.28 3.3‐mm wedgewire screen 2013 2015 0.109 98.36 3.77 0.077 98.29 3.77 2,602 98.28 3.6‐mm wedgewire screen 2013 2015 0.109 98.36 3.77 0.077 98.29 3.77 2,602 98.28 3.9‐mm wedgewire screen 2013 2015 0.109 98.36 3.77 0.077 98.29 3.77 2,602 98.28 3.Closed Cycle 2029 2029 0.87 86.42 1 0.617 85.57 1 20,461 85.6 
ASA Analysis & Communication, Inc.

Figure 10 Result of sensitivity analysis for % reduction of equivalent age 1 losses for wedgewire screen slot widths of 1, 3, 6, an

assumptions about avoidance and exclusion survival. 
ASA Analysis & Communication, Inc.

Table 28 Annual equivalent age 1 entrainment losses (millions) for RIS with existing technology at IPEC units 2 and 3. 

 2001 2002 2003 2004 2005 2006 2007 

Bay anchovy 0.8289 1.9145 1.7301 2.1453 2.5029 1.7236 4.715American shad 0.0002 0.0001 0.0001 0 0 0 0Striped bass 0.2952 0.1081 0.5614 0.1542 0.1478 0.0763 0.1555Atlantic tomcod 0.0295 0.0016 0.0069 0.0186 0.0118 0.0033 0.002White perch 0.0576 0.2415 0.3472 0.134 0.0897 0.1307 0.0541Alosa sp 0.0359 0.0581 0.0869 0.0191 0.0327 0.0121 0.0256
ASA Analysis & Communication, Inc. 

60

References 

ASA. 2009. 2007 Year Class Report for the Hudson River Estuary Monitoring Program. 

Report prepared for Dynegy Roseton L.L.C., Entergy Nuclear Indian Point 2 L.L.C., 

Entergy Nuclear Indian Point 3 L.L.C., and Mirant Bowline L.L.C. 

Beamish, F.W.H. 1978. Swimming capacity. Fish Physiology, Vol. VII:101-187. 

EA. 1981. Indian Point Generation Station entrainment survival and related studies. 

1979 annual report prepared for Consolidated Edison Company of New York, Inc. and 

Power Authority of the State of New York. 

EA. 1982. Indian Point Generation Station entrainment survival and related studies. 

1980 annual report prepared for Consolidated Edison Company of New York, Inc. and 

Power Authority of the State of New York. 

EA. 1984. Indian Point Generating Station entrainment abundance and outage 

evaluation. 1983 annual report to Consolidated Edison Company of New York and New 

York Power Authority. Ecological Analysts. New York 

EA. 1985. Indian Point Generating Station entrainment abundance and outage 

evaluation. 1984 annual report to Consolidated Edison Company of New York and New 

York Power Authority. Ecological Analysts. New York. 

EA. 1989. Indian Point Generating Station 1988 entrainment survival study. Report to 

Consolidated Edison Company of New York and New York Power Authority. EA 

Engineering, Science and Technology, Inc. New York. 

EPRI (Electric Power Research Institute). 2003. Laboratory evaluation of wedgewire 

screens for protecting early life stages of fish at cooling water intakes. Report 1005339. 

EPRI. 2004. Extrapolating Impingement and Entrainment Losses to Equivalent Adults 

and Production Foregone. Report 1008471. 

Fletcher, R. I. 1990. Flow dynamics and fish recovery experiments: water intake 

systems. Transactions of the American Fisheries Society. 119:393-415. 

Heuer, J.H., and D.A. Tomljanovich. 1978. A study on the protection of fish larvae at 

water intakes using wedge-wire screening. TVA Tech. Note B26. 60 p. 

Horst, T. J. 1975. The assessment of impact due to entrainment of ichthyoplankton. P. 

107-118 in S. B. Saila (ed.) Fisheries and energy production. D. C. Heath and Company, 

Lexington, MA. 300p. 

Jinks S.M., G. Lauer, and M. Loftus. 1981. Advances in Techniques for Assessment of 

Ichthyoplankton Entrainment Survival. Pp 91-110 in: Issues Associated with Impact 

Assessment: Proceedings of the Fifth National Workshop on Entrainment and 

Impingement (L. Jensen, ed.) Ecological Analysts. Sparks, MD. 
ASA Analysis & Communication, Inc. 

61

Lagler, K. F., J. E. Bardach, and R. R. Miller. 1962. Ichthyology. John Wiley & Sons, 

New York. 545p. 

Mattson, M. T., J. B. Waxman, and D. A. Watson. 1988. Reliability of Impingement 

Sampling Designs: An Example from the Indian Point Station. American Fisheries 

Society Monograph 4:161-169. 

McGroddy, P. M., and R. L. Wyman. 1977. Efficiency of nets and a new device for 

sampling living fish larvae. Journal Fisheries Research Board Canada 34: 571-574. 

Muessig, P. H., J. R. Young, D. S. Vaughan, and B. A. Smith. 1988. Advances in field 

and analytical methods for estimating entrainment mortality factors. Pages 124-132 in

Barnthouse, L. W., R. J. Klauda, D. S. Vaughan, and R. L. Kendall, editors. Science law 

and Hudson River power plants. American Fisheries Society, Monograph 4. Bethesda, 

Maryland. 

NAI (Normandeau Associates). 1987a. Indian Point Generating Station entrainment 

abundance program. 1985 annual report to Consolidated Edison Company of New York 

and New York Power Authority. Normandeau Associates, New Hampshire. 

NAI. 1987b. Indian Point Generating Station entrainment abundance Program. 1986 

annual report to Consolidated Edison Company of New York and New York Power 

Authority. Normandeau Associates, New Hampshire. 

NAI. 1988a. Indian Point Generating Station entrainment abundance program. 1987 

annual report to Consolidated Edison Company of New York and New York Power 

Authority. Normandeau Associates, New Hampshire. 

NAI. 1988b. Danskammer Point Station fine mesh screen evaluation. 1986 Study. 

Report to Central Hudson Gas & Electric Corporation.. Normandeau Associates, New 

Hampshire. 

NAI. 1989. Danskammer Point Station fine mesh screen evaluation. 1988 Study. Report 

to Central Hudson Gas & Electric Corporation.. Normandeau Associates, New 

Hampshire. 

O’Connor, J. M. and S. A. Schaffer. 1977. The effect of sampling gear on the survival 

of striped bass ichthyoplankton. Chesapeake Science 18:312-315. 

Rago, P. J. 1984. Production Forgone: An Alternative Method for Assessing the 

Consequences of Fish Entrainment and Impingement Losses at Power Plants and Other 

Water Intakes. Ecological Modeling 24(1/2):79-111. 

Ricker, W. E. 1973. Linear regressions in fishery research. J. Fish. Res. Board Can. 

30:1275-1286.. 

USEPA 2006. Regional Benefits Analysis for the Final Section 316(b) Phase III Rule for 

Existing Facilities. EPA-821-R-04-007. 

http://www.epa.gov/waterscience/316b/phase3/ph3docs/p3-rba-final-part1.pdf 
ASA Analysis & Communication, Inc. 

62

Weisberg, S.B., W.H. Burton, F. Jacobs, and E.A. Ross. 1987. Reductions in 

ichthyoplankton entrainment with fine-mesh, wedge-wire screens. N. Amer. J. 

Fish. Manag. 7:386-393. 

Yin, M. C. and J. H. S. Blaxter. 1987. Escape speeds of marine fish larvae during early 

development and starvation. Marine Biology 96:459-468. 

Young, J. R. 2009. Comparison of failure time analysis and Abbott’s formula for 

estimating survival of organisms entrained at power stations. North American Journal of 

Fisheries Management 29:263-278. 

Young, J. R., W. P. Dey, S. M. Jinks, and D. T. Mosier. 2009. Survival of striped bass 

entrained into the cooling system of two Hudson River power plants. North American 

Journal of Fisheries Management. 29:1015-1034. 
Appendix B 

BIOLOGICAL EVALUATION OF INTAKE SCREEN 

ALTERNATIVES TO REDUCE IMPINGEMENT AND 

ENTRAINMENT LOSSES AT INDIAN POINT ENERGY CENTER

Prepared for 

ENTERGY SERVICES, INC. 

1340 Echelon Parkway 

Jackson, Mississippi 39213 

Prepared by 

NORMANDEAU ASSOCIATES, INC. 

25 Nashua Road 

Bedford, New Hampshire 03110 

R-19998.001 

February 2010 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 ii Normandeau Associates, Inc.

Table of Contents 

Page 

1.0 INTRODUCTION .................................................................................................................................. 1

2.0 MESH SELECTIVITY ......................................................................................................................... 1

2.1 PHYSICAL EXCLUSION FACTORS .................................................................................................... 2

2.1.1 Larvae .............................................................................................................................. 2

2.1.2 Eggs ................................................................................................................................. 5

2.2 WEDGEWIRE AVOIDANCE FACTORS ............................................................................................... 5

2.3 REFERENCES ................................................................................................................................ 10

3.0 IMPINGEMENT MORTALITY OF SMALL FISH ON FINE-MESH INTAKE 

SCREENS AT DANSKAMMER POINT STATION ....................................................................... 19

3.1 APPROACH ................................................................................................................................... 19

3.2 RESULTS ...................................................................................................................................... 21

3.2.1 Bay Anchovy ................................................................................................................. 21

3.2.2 Striped Bass ................................................................................................................... 22

3.2.3 White Perch ................................................................................................................... 22

3.2.4 Clupeids ......................................................................................................................... 23

3.2.5 All Other Fish Taxa ....................................................................................................... 23

3.2.6 All Fish Taxa Combined ................................................................................................ 24

3.3 REFERENCES ................................................................................................................................ 25

4.0 LOVETT GUNDERBOOM EFFECTIVENESS AND MESH SELECTIVITY 

ANALYSIS ........................................................................................................................................... 36

4.1 APPROACH ................................................................................................................................... 36

4.2 RESULTS ...................................................................................................................................... 37

4.3 REFERENCES ................................................................................................................................ 39

5.0 VERIFICATION OF COMPUTER CODE ...................................................................................... 42

5.1 APPROACH ................................................................................................................................... 42

5.2 PROGRAM 1H.SAS (22SEP09 REVISION) ....................................................................................... 43

5.2.1 Entrainment Section 1—Estimate River Standing Crops for 1983-1987 and 

2000-2007 ...................................................................................................................... 43

5.2.2 Entrainment Section 2—Estimate Entrainment Densities for 1983-1987 ...................... 44

5.2.3 Entrainment Section 3—Relationship of Entrainment Density to Standing Crop ......... 45

5.2.4 Entrainment Section 4—Predict 2000-2007 Entrainment Densities .............................. 45

5.2.5 Entrainment Section 5—Estimate 2000-2007 Entrainment Length-Frequencies .......... 45

5.2.6 Entrainment Section 6—Create Flow Data Sets ............................................................ 46

5.2.7 Entrainment Section 7—Survival and Exclusion Parameter Values.............................. 46

5.2.8 Entrainment Section 8—Calculate Numbers and Losses by Case ................................. 46

5.2.9 Entrainment Section 9—Calculate Equivalent Life Stage Values ................................. 48

5.2.10 Entrainment Section 10—Convert Entrainment Loss to Equivalent Loss ..................... 49

5.2.11 Entrainment Section 11—Produce Output Tables ......................................................... 50

5.2.12 Impingement Sections 1 and 2—River Abundance in 1983-1987 and 2000-

2007; Correlation of Standing Crops ............................................................................. 51

5.2.13 Impingement Section 3—Merge Abundance Ratios with Densities and Estimate 

Impingement .................................................................................................................. 51

5.2.14 Impingement Section 4—Convert to Equivalent Losses ............................................... 52

5.2.15 Outstanding Consideration ............................................................................................ 52

5.3 PROGRAM IP-COLLEFF1981 - 1990.SAS (22SEP09 REVISION) ..................................................... 52
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 iii Normandeau Associates, Inc.

5.3.1 Step 1—Calculate Collection Efficiency Coefficients ................................................... 52

5.4 PROGRAM IP-STRATAIMPBYLENGTHCLASS1981 - 1990.SAS (22SEP09 REVISION) ..................... 53

5.4.1 Step 2—Join Catch Data to the Collection Efficiency Data from Step 1 ....................... 53

5.4.2 Step 3—Calculate Strata Numbers ................................................................................ 53

5.4.3 Step 4—Bring in Plant Operation Data ......................................................................... 54

5.5 VERIFICATION OF SENSITIVITY ANALYSIS AND CUMULATIVE ANALYSIS .................................... 54
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 iv Normandeau Associates, Inc.

List of Figures

Page 

Figure 2-1. Observed wedgewire avoidance factors by length, species, and slot width, with a 

generalized relationship between larval length and wedgewire avoidance factor. ........... 11

Figure 3-1. Adjusted (for differences in volume sampled) length frequency distributions for 

fish impinged on the 3.2 mm fine mesh conventional traveling screens at 

Danskammer Unit 3 and the 9.5 mm standard mesh conventional traveling 

screens at Unit 4, 1 May through 23 August 1988. ............................................................ 26

Figure 3-2. Relative (percent) adjusted length frequency distributions for fish impinged on 

the 3.2 mm fine mesh conventional traveling screens at Danskammer Unit 3 and 

the 9.5 mm standard mesh conventional traveling screens at Unit 4, 1 May 

through 23 August 1988. ..................................................................................................... 27

Figure 3-3. Cumulative relative length frequency distributions for fish impinged on the 3.2 

mm fine mesh conventional traveling screens at Danskammer Unit 3 and the 9.5 

mm standard mesh conventional traveling screens at Unit 4, 1 May through 23 

August 1988. ....................................................................................................................... 28

Figure 4-1. Length Frequency (one mm length groups) of all larval fish taxa combined 

collected by simultaneous pairs of samples taken inside (test) or outside (control) 

of a deployed AFB at Lovett Station on the Hudson River, New York, from May 

through October 2004, 2005 and 2007 (2006 length data not available). ......................... 40
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 v Normandeau Associates, Inc.

List of Tables

Page 

Table 2-1. Physical exclusion factors for Atlantic tomcod. ................................................................. 12

Table 2-2. Physical exclusion factors for striped bass. ........................................................................ 13

Table 2-3. Physical exclusion factors for white perch. ........................................................................ 14

Table 2-4. Physical exclusion factors for river herring and American shad. ...................................... 15

Table 2-5. Physical exclusion factors for bay anchovy. ...................................................................... 16

Table 2-6. Physical exclusion factors for eggs. .................................................................................... 17

Table 2-7. Data used to fit a generalized curve for estimating wedgewire avoidance as a 

function of length. ............................................................................................................... 18

Table 3-1. Results of the Danskammer fine mesh traveling screen impingement survival 

study, 1 May – 23 August 1988. (Unit 3 = 3.2 mm fine mesh, Unit 4 = 9.5 mm 

standard mesh). .................................................................................................................... 29

Table 3-2. Number and percent of fish collected in Length Class 1 (representing the fraction 

of small fish retained on the fine mesh screen of Unit 3 but not on the standard 

mesh screen of Unit 4) and Length Class 2 (representing the fraction of large fish 

retained on both the fine mesh and standard mesh screens) for which length was 

determined, adjusted for differences in intake flow between Danskammer Point 

Station Unit 3 and Unit 4, 1 May – 23 August 1988. (Unit 3 = 3.2 mm fine 

mesh, Unit 4 = 9.5 mm standard mesh). ............................................................................. 30

Table 3-3. Number and percent of fish collected in Length Class 1 (representing the fraction 

of small fish retained on the fine mesh screen of Unit 3 but not on the standard 

mesh screen of Unit 4) that contributed to the combined impingement collection 

from both Units, adjusted for differences in intake flow between Danskammer 

Point Station Unit 3 and Unit 4, 1 May – 23 August 1988. (Unit 3 = 3.2 mm fine 

mesh, Unit 4 = 9.5 mm standard mesh). ............................................................................. 31

Table 3-4. Number of fish and percent impingement survival for all fish for which length 

was determined, adjusted for differences in intake flow between Danskammer 

Point Station Unit 3 and Unit 4, 1 May – 23 August 1988. (Unit 3 = 3.2 mm fine 

mesh, Unit 4 = 9.5 mm standard mesh). ............................................................................. 32

Table 3-5. Number of fish and percent impingement survival for Length Class 1 

representing the fraction of small fish retained on the fine mesh screen (Unit 3) 

but not on the standard mesh screen (Unit 4) for which length was determined, 

adjusted for differences in intake flow between Danskammer Point Station Unit 

3 and Unit 4, 1 May – 23 August 1988. (Unit 3 = 3.2 mm fine mesh, Unit 4 = 

9.5 mm standard mesh). ...................................................................................................... 33

Table 3-6. Number of fish and percent impingement survival for Length Class 2 

representing the fraction of large fish retained on both the fine mesh and standard 

mesh screens for which length was determined, adjusted for differences in intake 

flow between Unit 3 and Unit 4, 1 May – 23 August 1988. (Unit 3 = 3.2 mm 

fine mesh, Unit 4 = 9.5 mm standard mesh). ..................................................................... 34

Table 3-7. Comparison of 8-hour survival (percent alive) and the total number of fish 

collected (N Total) for common fish impinged on the Danskammer Point Station 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 vi Normandeau Associates, Inc.

fine mesh conventional traveling screens at Unit 3 (3.2 mm), the standard mesh 

traveling screens at Unit 4 (9.5 mm) tested between 1 May and 23 August 1988, 

and the Ristroph screen version 2 installed and tested at Indian Point Unit 2, 

screen well 26 during 16 September through 24 October 1986. ........................................ 35

Table 4-1. Summary of annual percent exclusion effectiveness for fish larvae collected by 

simultaneous pairs of samples taken inside and outside of a deployed AFB at 

Lovett Station on the Hudson River, New York, from May through October 

2004, 2005, 2006 and 2007. ................................................................................................ 41
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 1 Normandeau Associates, Inc.

1.0 INTRODUCTION

Entergy Nuclear Indian Point 2, LLC and Entergy Nuclear Indian Point 3, LLC (“Entergy”) retained 

Normandeau Associates, Inc. (“Normandeau”) to provide biological support for its assessment of 

potential alternative intake technologies for the Indian Point Entergy Center (“IPEC”) nuclear 

powered electric generating stations 2 and 3 (individually, “Unit 2” and “Unit 3,” and collectively, the 

“Stations”). This evaluation was undertaken as part of Entergy’s alternative technology assessment 

performed pursuant to the New York State Department of Environmental Conservation (“NYSDEC”) 

Assistant Commissioner’s August 13, 2008 Interim Decision.1

 Normandeau’s contributions to the 

alternatives analysis presented in this report are an evaluation of the potential for narrow slot width 

wedgewire screens or fine-mesh intake screens to reduce rates of entrainment (Section 2.0), analysis 

of impingement mortality of small fish on fine-mesh intake screens (Section 3.0), analysis of the 

potential for a fine-mesh aquatic filter barrier (“AFB”) to reduce rates of entrainment and 

impingement (Section 4.0), and quality control verification of the computer programs projecting 

entrainment and impingement losses under the various alternatives (Section 5.0).2

2.0 MESH SELECTIVITY

The IPEC analysis uses Normandeau’s estimates of the exclusion potential of various mesh sizes as 

part of the evaluation of the biological effectiveness of wedgewire screens and fine-mesh intake 

screens. The exclusion estimates represent two distinct processes. One process, which applies to 

both wedgewire screens and fine mesh intake screens, is the physical exclusion of eggs and larvae by 

withdrawing cooling water through openings that are too small for the eggs and larvae to pass 

through. This process is represented by the “physical exclusion factor,” which represents the 

proportion of the organisms that would have been entrained through the existing screens that are 

excluded from the facility’s cooling water by the finer mesh alternative. The purpose of the physical 

exclusion factor is to enable estimation of the reduced number that would be entrained through the 

fine-mesh alternative technology: 

Ef = ( E ) ( 1–Pe ) (Equation 1) 

where Ef = number entrained through fine-mesh intake screens, 

 E = number entrained through existing intake screens, and 

 Pe = proportion of the currently entrained organisms that would be excluded by a finer 

mesh alternative screening technology (physical exclusion factor). 

The second process, which applies only to wedgewire screens, is the ability of larvae to actively avoid 

being entrained through wedgewire screens. This is represented by the “wedgewire avoidance 

factor,” which is the proportion of organisms of a size vulnerable to entrainment that actively avoid 

 

1

 As noted in Biological Effectiveness of Alternative Intake Technologies for Indian Point Units 2 and 3 

(Barnthouse et al. 2010), a 2003 draft permit issued by NYSDEC Staff proposed modifications to the cooling 

water intake structure at the Stations. These modifications include possible construction and operation of two 

large counter-flow, forced draft, plume abated hybrid cooling towers. 

2

 This report supports the report entitled “Biological Effectiveness of Alternative Intake Technologies for Indian 

Point Units 2 and 3” prepared by Lawrence W. Barnthouse of LWB Environmental Services, Inc., Douglas G. 

Heimbuch of AKRF, Inc., Mark T. Mattson of Normandeau Associates, Inc., and John R. Young of ASA 

Analysis & Communication, Inc. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 2 Normandeau Associates, Inc.

being entrained. The hydrodynamic transport of organisms out of the withdrawal zone of the 

wedgewire screens by means of water currents (“sweeping flows”) is not estimated separately in this 

evaluation, but is included as part of the wedgewire avoidance factor. The purpose of the wedgewire 

avoidance factor is to be used together with the physical exclusion factor to enable estimation of the 

reduced number that would be entrained through wedgewire screens: 

Ew = ( E ) ( 1–Pa ) ( 1–Pe ) (Equation 2) 

where Ew = number entrained through wedgewire screens, 

 E = number entrained through existing intake screens, 

 Pa = proportion avoiding entrainment (wedgewire avoidance factor), and 

 Pe = proportion excluded (physical exclusion factor). 

The following narrative describes the rationale, assumptions, data, and procedures used to estimate 

the physical exclusion factors (Section 2.1) and wedgewire avoidance factors (Section 2.2) for the 

IPEC alternatives analysis. 

2.1 PHYSICAL EXCLUSION FACTORS

2.1.1 Larvae 

Entrainability of the early life stages of fish depends on what sizes of them can fit through the mesh 

openings. Estimates of the physical exclusion factor Pe for larvae are based on their “limiting 

dimension,” reflecting the fundamental assumption that a small fish attempting to avoid the screen 

will typically orient itself to swim directly away from the screen surface, so that if it is entrained it is 

drawn tail first through the mesh opening by the intake current. Thus the limiting dimension is not 

the length of the fish, but its thickness, which could be either the head or the thickest or deepest part 

of the body. If either the greatest width or greatest depth of the fish exceeds the width of the mesh 

opening, the fish will usually not be entrained. Greatest body depth (“GBD”) was selected to 

represent the limiting dimension for this evaluation because it is usually the most available 

measurement other than total length. Although GBD might in some cases be slightly smaller than 

head capsule width, head capsule depth, or greatest body width, the difference would be very small, 

and GBD is still a reasonable representation of the limiting dimension of the larva. 

Estimates of Pe based on GBD can overestimate the actual fraction excluded at the upper end of the 

entrainment/impingement transition size range if some larvae are compressed and forced through the 

screen, if some pass through holes in the screen, if some pass through gaps beside the screen, or if 

some are carried over the top of the screen and fall off behind the screen during screen rotation and 

washing. Estimates of Pe based on GBD can underestimate the fraction excluded at the lower end of 

the entrainment/impingement transition size range, because of fish that are small enough to fit 

through the screen tail first but are instead impinged sideways across the screen mesh. No attempt 

was made to adjust for these biases because there is insufficient information available on which to 

base such adjustments. 

Pe varies depending on the species, the size of the individual, and the width of the mesh openings. 

The evaluation focused on selected species designated as Representative Important Species for IPEC: 

Atlantic tomcod, striped bass, white perch, American shad, alewife, blueback herring, and bay 

anchovy (Pe estimates were not attempted for spottail shiner because of insufficient data). Mesh 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 3 Normandeau Associates, Inc.

opening widths evaluated were 1.0 mm, 1.5 mm, 2.0 mm, 3.0 mm, 6.0 mm, and 9.0 mm. Estimates 

of Pe were made for 1-mm intervals from 2 mm through 70 mm. Each length class is expressed as an 

integer length that represents all lengths that round to that value (e.g., for lengths recorded to the 

nearest 0.1 mm, the 2 mm length class includes all lengths from 1.5 mm through 2.4 mm). 

Estimates of Pe were primarily based on data from IPEC entrainment samples collected in 1986, 

which provided GBD and total length measurements to the nearest 0.1 mm for over 50,000 larvae 

(Normandeau 1987). Data for alewife and blueback herring were pooled with the data for 

unidentified clupeids (“river herring”), since only a few of the older young-of-the-year were 

identified to the species level. Sample sizes for American shad were low (a maximum of eight fish in 

any 1-mm length class), so because of the similarity in body shape to the closely related alewife and 

blueback herring, American shad data were pooled with the river herring data. For each 1-mm length 

class within a taxon, the proportion of GBD measurements exceeding each of the six selected mesh 

sizes was calculated as a preliminary estimate of Pe. 

For striped bass, white perch, clupeids (American shad and river herring), and bay anchovy, the 

number of measurements within many of the length classes was very good (over 50 for many length 

classes, with several even exceeding 1,000), providing a good basis for the Pe estimates. There were, 

however, some length classes with no measurements, or very few. Logistic curves fit to the data did 

not fit the data very well. For many of the most intensively sampled length classes (where Pe was 

therefore known with a high degree of precision) the Pe estimates from the curves were not very close 

to the Pe estimates from the actual data. Rather than sacrificing the quality of the estimates in the 

length classes containing most of the larvae for the sake of generating logistic regression estimates for 

the non-sampled length classes, the IPEC biologist team chose to use the Pe estimates from the actual 

data rather than from logistic models. 

Although length classes with missing estimates would minimally affect the outcome of the analysis 

(since they are the length classes rarely entrained) they still needed Pe estimates. Most of the missing 

values were obviously outside the entrainment/impingement transition range, and could easily be 

estimated by zero or one. When a missing value fell within the entrainment/impingement transition 

range, it was estimated “by eye” based on values in the sampled length classes. 

Another difficulty was that in some length classes there were data, but they were based on a limited 

number of measurements and the resulting Pe estimates were questionable because they did not agree 

with the overall pattern shown by the adjacent well sampled length classes. Some values outside the 

principal entrainment/impingement transition range appeared to be unduly influenced by questionable 

values. For example, a length class that should have had a Pe estimate at or close to 1.00 based on the 

overall pattern of the data might have a Pe estimate of 0.00 or 0.50 because of a single “outlier” 

specimen (which could have been due to a measuring or data recording error). Original values that 

were influenced by one or more outliers were smoothed using interpolation between the neighboring 

valid data to preserve the integrity of the overall pattern. 

For the mesh widths of 6 and 9 mm there were almost no useable data, except for Atlantic tomcod. Pe

estimates for 6 and 9 mm mesh for the other four taxa were therefore based on estimates from the 

literature of the average length at which body depths of 6 and 9 mm are attained. Those length 

classes were assigned Pe = 0.50. To represent the E/I transition zone for these cases, Pe estimates of 

0.05, 0.15, and 0.30 were assigned to the three length classes below the length class with Pe = 0.50 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 4 Normandeau Associates, Inc.

and Pe estimates of 0.70, 0.85, and 0.95 were assigned to the three length classes above the length 

class with Pe = 0.50, based on the pattern seen in the well sampled length classes. 

The resulting estimates of Pe are shown in Tables 2-1 through 2-5. All Pe estimates resulting from 

filling in missing length classes by interpolation are clearly identified by red font; also the number of 

actual measurements available for each length class is shown. 

Results from actual field and laboratory studies were examined to determine how well the Pe

estimates based on GBD agreed with empirical observations. EA (1977) conducted a field test of 

retention on 2.5-mm mesh at IPEC using hatchery-reared striped bass larvae. Large numbers of 

larvae (averaging 7 mm and 9 mm in two batches) were released in front of the screen, with minimal 

(0.16%) impingement. Wild striped bass larvae impinged on 16 and 21 June were late post yolk-sac 

larvae (“PYSL”) ranging from 10 to18 mm in length and early young-of-the-year (“YOY”) 17-23 mm 

in length, while concurrently collected larvae from unscreened intake samples contained an 

overlapping but smaller length distribution of striped bass larvae. EA concluded that 7-9 mm larvae 

were not effectively excluded and that 10-18 mm larvae were the smallest ones effectively retained by 

the 2.5-mm mesh. An entrainment/impingement transition range for striped bass of 10-18 mm is 

consistent with the GBD analysis for striped bass (Table 2-2). 

In flume testing conducted by Alden in 1978-1980 (summarized by Fletcher 1990), the 50% retention 

sizes for striped bass were roughly 25-40% longer than predicted by the GBD analysis. This would 

seem to indicate that larvae were extruded through the mesh in Alden’s experiments when they were 

theoretically too big to be entrained. Although Alden’s tests did not find any significant relationship 

between retention and water velocity, of the five speeds they tested only the lowest (15 cm/s) was 

relevant to speeds under consideration for IPEC, so the applicability of most of the Alden data to the 

mesh selectivity analysis for IPEC is questionable. 

Impingement rates for white perch, striped bass, and river herring smaller than 40 mm were much 

higher for 3.0-mm mesh intake screens than for 9.5-mm mesh screens at Danskammer Point Station 

(Normandeau 1989). For bay anchovy the 3.0-mm screens also had higher impingement rates for the 

40-49 mm length class. These results are consistent with the entrainment/impingement transition 

sizes predicted by the GBD analysis for bay anchovy (Table 2-5). 

Alden (2003) reported flume tests of retention on a standard-mesh screen (it appeared to have 3/8 

inch square mesh in their photos). The 50% retention size for hybrid striped bass was about 45 mm 

(converted from FL to TL), which is consistent with the GBD analysis, although the IPEC data used 

in the GBD analysis only included two striped bass in that size range. Alden’s 50% retention size for 

bay anchovy was about 66-71 mm, slightly larger than the 55-60 mm predicted by the GBD analysis, 

although Alden’s sample size was small and the GBD prediction was extrapolated from smaller sizes. 

Alden’s study does not provide convincing evidence that the exclusion factors based on GBD need 

adjustment, but the comparison is weak because of the small sample sizes and different size ranges. 

There is also some uncertainty in the dimensions of Alden’s test mesh, because the dimensions of 

Alden’s test mesh were not specified. 

EPRI (2009) reported flume tests of larval retention of eight freshwater species on 0.5-mm, 1.0-mm, 

and 2.0-mm mesh at different flume velocities. One indication of the validity of the GBD approach 

for fine-mesh screens was that the only species effectively retained by 2.0-mm mesh was blue catfish, 

which had head capsule depths >2.0 mm. Otherwise, the size ranges of impinged and entrained 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 5 Normandeau Associates, Inc.

larvae were too narrow to evaluate the entrainment/impingement transition ranges, so this study does 

not provide much information for evaluating the GBD estimates of exclusion. 

Based on comparisons with the results of these lab and field studies, the estimates of Pe based on 

GBD analysis appear to be realistic. 

2.1.2 Eggs 

For fish eggs, which are spherical, or nearly so, the limiting dimension is simpler than for larvae. If 

the egg diameter is larger than the width of the mesh openings, the egg would normally be excluded 

by the intake screens (assuming that the through-mesh velocity is not high enough to deform the egg 

sufficiently to “extrude” it through the mesh). Egg diameters were not measured during the 1986 

entrainment abundance program at IPEC, so egg diameters for the selected species were estimated 

from the ranges reported by Jones et al. (1978) for alewife, blueback herring, American shad, and bay 

anchovy; Hardy (1978a) for Atlantic tomcod; and Hardy (1978b) for striped bass and white perch. 

For the slightly elliptical eggs of bay anchovy, the minimum and maximum diameter were each 

estimated by averaging the values for the minor and major axes at a salinity of 5 parts per thousand. 

From the range, the median egg diameter was estimated as the average of the minimum and 

maximum value. Since 99.73% of the items in a normal frequency distribution lie within ±3 standard 

deviations of the mean (Sokal and Rohlf 1969), the standard deviation was estimated as one-sixth of 

the range. The proportion of eggs with diameters larger than screen opening widths of 1.0, 1.5, 2.0, 

3.0, 6.0, and 9.0 mm were then determined from tabulated areas of the normal curve using the median 

and standard deviation estimates of egg diameter to estimate the physical exclusion factor Pe (Table 

2-6). 

Estimates of Pe based on egg diameter could overestimate the actual fraction excluded if some eggs 

are “extruded” (compressed and forced through the screen), if some pass through holes in the screen, 

if some pass through gaps beside the screen, or if some are carried over the top of the screen and fall 

off behind the screen during screen rotation and washing. No attempt was made to adjust for this bias 

because there is insufficient information available on which to base an adjustment. 

2.2 WEDGEWIRE AVOIDANCE FACTORS

As discussed in Attachment B-1 to this appendix, a wide variety of studies performed by many 

investigators have demonstrated that fish larvae possess the ability to swim and to use their 

swimming ability to evade predators, sampling gears, and, at least in under certain circumstances, 

intake screens. Of particular relevance here, Heuer and Tomljanovich (1978) found that the 

proportions of larvae entrained through wedgewire screen panels in a laboratory flume were much 

lower than the proportions of flow entrained, indicating that larvae small enough to be entrained are 

capable of detecting and avoiding wedgewire screens (Heuer and Tomljanovich 1978). To avoid 

entrainment, larvae need only to swim far enough to move out of the flow entrained through the 

screen and into the sweeping flow that bypasses the screen. 

If active avoidance and physical exclusion are two distinct factors contributing to entrainment 

reduction, their combined effect can be expressed by the following generalization for wedgewire 

screens: 

PE = ( 1–Pa ) ( 1–Pe ) (Equation 3) 

where PE = proportion of larvae within the withdrawal zone that are entrained, 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 6 Normandeau Associates, Inc.

 Pa = proportion of larvae within the withdrawal zone that avoid entrainment, and 

 Pe = proportion of larvae within the withdrawal zone that do not avoid entrainment but 

are physically excluded. 

In field and lab tests of wedgewire screens, only PE (the combined effect of Pa and Pe) can be directly 

observed. Wedgewire avoidance factors can be estimated from experimentally observed values of PE

using the physical exclusion factors Pe developed in Section 2.1 above and solving Equation 3 for Pa: 

Pa = 1 – [ ( PE / ( 1–Pe ) ] (Equation 4) 

where Pa = proportion of larvae within the withdrawal zone that avoid entrainment, 

 PE = proportion of larvae within the withdrawal zone that are entrained, and 

 Pe = proportion of larvae within the withdrawal zone that do not avoid entrainment but 

are physically excluded. 

The flume tests by Heuer and Tomljanovich (1978) compared 0.5 mm, 1.0 mm, and 2.0 mm 

wedgewire screen panels; through-slot velocities of 7.6, 15.2, and 22.9 cm/s; and sweeping velocities 

of 7.6, 15.2, 30.5, and 61.0 cm/s. The test species were striped bass, largemouth bass, smallmouth 

bass, bluegill, walleye, channel catfish, and muskellunge. For each test, a wedgewire panel was 

mounted flush with either the bottom or side of the flume, withdrawing water perpendicular to the 

direction of flow in the flume. In the absence of physical exclusion or active avoidance (or 

attraction), the expected proportion of larvae not drawn through the wedgewire panel (the proportion 

“bypassed”) was the same as the proportion of the flume’s flow that was bypassed. The expected 

proportion of larvae bypassed was compared to the observed proportion of larvae that actually were 

bypassed. The larvae in these experiments were distributed uniformly both within the withdrawal 

zone and within the flow that bypassed the screen panel, which can be accounted for by inserting 

another term into Equation 3: 

PE = ( 1–Pb ) ( 1–Pa ) ( 1–Pe ) (Equation 5) 

where PE = proportion of larvae within the entire flume that were entrained, 

Pb = proportion of the flume’s flow that bypassed the screen panel, 

 Pa = proportion of larvae within the withdrawal zone that avoided entrainment, and 

 Pe = proportion of larvae within the withdrawal zone that did not avoid entrainment 

but were physically excluded. 

Solving for Pa to estimate the avoidance factor from the Heuer and Tomljanovich (1978) flume tests, 

Pa = 1 – { PE / [ ( 1–Pb ) ( 1–Pe ) ] } (Equation 6) 

where Pa = proportion of larvae within the withdrawal zone that avoided entrainment, 

 PE = proportion of larvae within the entire flume that were entrained (observed by the 

experimenters), 

 Pb = proportion of the flume’s flow that bypassed the screen panel (determined by the 

experimenters from measurements of the flow in the flume and the flow 

withdrawn through the wedgewire panel), and 

 Pe = proportion of larvae within the withdrawal zone that did not avoid entrainment 

but were physically excluded (from Section 2.1). 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 7 Normandeau Associates, Inc.

To represent the system under consideration for IPEC, this evaluation of the Heuer and Tomljanovich 

(1978) data was limited to the results for striped bass larvae at a slot velocity of 0.15 m/s, flume 

velocities of 0.15 and 0.30 m/s, and slot widths of 1.0 and 2.0 mm from their Tables 1 and 2. Striped 

bass were tested by in two series of trials, one in April (lengths averaging 5.6 mm) and one in June 

(lengths averaging 5.9 mm). For larvae exposed to panels with slots 1 mm wide, the wedgewire 

avoidance factor (Pa) averaged 0.309 in April tests and 0.483 in June tests. For striped bass larvae 

exposed to panels with slots 2 mm wide, Pa averaged 0.412 in April tests and 0.755 in June tests. 

Each of these values was the mean of Pa for four trials, where a trial was the average of three replicate 

releases of about 100-200 larvae each. The overall averages by slot width for the April and June tests 

combined (average length 5.75 mm) were Pa=0.396 for 1-mm screening and Pa=0.583 for 2-mm 

screening. 

In 2001 and 2002, flume testing of cylindrical wedgewire screen entrainment and impingement was 

conducted by Alden Research Laboratory, Inc. (EPRI 2003). The screens were 12 inches in diameter 

and 44 inches long with 0.5, 1.0, and 2.0 mm slot widths, oriented both perpendicular and parallel to 

the flume flow. Flume speeds were 0.08, 0.15 and 0.30 m/s and slot velocities were 0.15 and 0.30 

m/s. Species and life stages tested included eggs of striped bass, white sucker, and alewife and larvae 

of striped bass, winter flounder, white sucker, rainbow smelt, yellow perch, common carp, and 

bluegill. Test organisms were released from a tube close to the screen at its centerline, so all would 

be vulnerable to entrainment or impingement (none were in the part of the flume flow that bypassed 

the screen, so Equation 4 above was the one applicable to these data). 

There appears to have been substantial extrusion of 8.9-mm striped bass larvae through 1.0-mm slots 

when the slot velocity was high (0.3 m/s) and the screens were mounted perpendicular to the flume 

flow, since only 15% of 8.9 mm larvae should fit through 1.0 mm slots but 67% and 68% of the 

larvae were entrained. Neither the slot velocity nor the screen orientation, however, is representative 

of the system proposed for IPEC. There was little or no avoidance for the 1.0 mm wedgewire screen 

in the parallel orientation at 0.30 m/s flume velocity, although those three experiments did not show 

the extreme extrusion as when the screen was oriented perpendicularly. Because of the high slot 

velocity, these also are not representative of the proposed IPEC system. Low avoidance was also 

seen for the 2.0 mm wedgewire screen in the perpendicular orientation, also not representative of the 

system proposed for IPEC. 

To best represent the system under consideration for IPEC, this evaluation of the EPRI (2003) data 

was therefore limited to the results of the striped bass larvae experiments conducted at a slot velocity 

of 0.15 m/s through 1.0 and 2.0 mm slots in screens oriented parallel to the flow in flume velocities of 

0.15 and 0.30 m/s. The mean Pa for 7.0-mm striped bass larvae and 1.0-mm slot width screens was 

0.706. The mean Pa for 8.3-mm striped bass larvae and 2.0-mm slot width screens was 0.464. 

Considered together, the results of Heuer and Tomljanovich (1978) and EPRI (2003) for striped bass 

on 1.0 and 2.0-mm wedgewire screens suggest a fairly consistent avoidance factor, with no indication 

of differences due to slot width. The size range of the striped bass larvae tested in these two studies 

was, however, too narrow to adequately detect any variation in avoidance behavior related to length. 

Observations over a wider range of lengths for other species were obtained in a field test of 

wedgewire screen exclusion conducted in 1982 and 1983 in a Maryland power plant intake canal by 

Weisberg et al. (1987). Their study compared densities of wild-caught larvae pumped through 1.0, 

2.0, and 3.0-mm slot width cylindrical wedgewire screens as well as through an unscreened sampling 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 8 Normandeau Associates, Inc.

port. Bay anchovy and naked goby larvae were the dominant species collected. No exclusion was 

demonstrated for eggs or larvae ≤4 mm, but densities of bay anchovy larvae ≥5 mm were lower for all 

three screens than for the unscreened samples. Mean densities entrained appeared to decrease with 

decreasing slot width, although this pattern was not statistically significant. Within the four larger 

size ranges (5-7, 8-10, 11-14, and ≥15 mm), entrained densities were significantly lower than open 

port densities for 15 of the 20 combinations of size group, sampling year, and slot width. Mean 

annual bay anchovy densities from Table 1 in Weisberg et al. (1987) were used as the basis for 

estimating PE. Because of unequal sample volumes and numbers of samples in the two years of the 

study, as well as zero catches for some size groups and slot widths, the densities from the two years 

were first averaged together, weighted by total sampling volume. Next, the proportion entrained for 

each size group and slot width (PE) was calculated as the ratio of entrained density to open port 

density to enable estimating Pa by Equation 4 using Pe from the GBD analysis. Negative values for Pa

in the ≤4 mm length class for all three slot widths were interpreted as artifacts of low catches and set 

to zero, resulting in the following wedgewire avoidance factors for bay anchovy larvae estimated 

from the data of Weisberg et al. (1987): 

1.0-mm screen 2.0-mm screen 3.0-mm screen 

≤4 mm larvae 0.000 0.000 0.000 

5-7 mm larvae 0.427 0.512 0.438 

8-10 mm larvae 0.860 0.747 0.662 

11-14 mm larvae 1.000 0.832 0.769 

≥15 mm larvae 0.874 0.793 0.839 

The above estimates of wedgewire avoidance are based on a wide range of sizes for bay anchovy and 

a limited size range for striped bass. To evaluate the best approach to estimate factors for other 

species, the estimates for striped bass and bay anchovy were compared within their common size 

range. Pa estimates for striped bass were 0.396 and 0.583 at 5.75 mm and 0.706 at 7.0 mm, compared 

to bay anchovy estimates of 0.427, 0.512, and 0.438 in the 5-7 mm length range. The good 

agreement among values for these two species, in spite of their different body shapes, supports using 

a single value (or set of values) of Pa for all species in the IPEC analysis. The Pa estimates for bay 

anchovy, the only species tested over a wide range of sizes, increase consistently with increasing size. 

This is consistent with the biology of fish larvae, which improve in swimming capability as they 

grow. Based on the similarity in avoidance between striped bass and bay anchovy of a comparable 

size, the increase in avoidance demonstrated by bay anchovy as they grow, and the similarity in 

avoidance among different slot widths tested, the 19 values highlighted in bold font above and 

summarized in Table 2-7 were used to fit a generalized exponential equation for estimating 

wedgewire avoidance as a function of length, applicable to all species in the IPEC analysis (illustrated 

in Figure 2-1): 

Pa = 1 – e [ –0.275 ( L – 4 ) ] (Equation 7) 

where Pa = proportion of larvae within the withdrawal zone that avoid entrainment, 

 e = base of natural logarithms (2.71828), 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 9 Normandeau Associates, Inc.

 L = total length (mm). 

Equation 7 applies when length ≥4 mm (when length <4 mm, Pa is defined as zero). 

Equation 7 was developed from laboratory tests of fish larvae representing the same species and sizes 

exposed to entrainment at IPEC. These tests studied small-scale (12 inches in diameter by 44 inches 

long), narrow slot, cylindrical wedgewire screens of the same proportions and orientation as those 

considered for application to IPEC. The resulting data were used to develop a performance curve 

(Figure 2-1) for 1 mm, 2 mm and 3 mm screens that expressed the probability of avoidance as a 

function of larval length. An important conclusion from our analysis of these data is that slot width 

did not have a significant influence on avoidance for the range of slot widths tested. This conclusion 

is supported by the narrow scatter of actual experimental observations about the predicted curve. The 

correlation coefficient was high (R2

 = 0.872), and larval length was the predominant factor 

influencing the curve. However, cylindrical wedgewire screens with slot widths greater than 3 mm 

were not tested. It is not clear from the available laboratory studies whether this avoidance 

relationship is applicable full-scale cylindrical wedgewire screens of larger slot widths, such as 6 mm 

or 9mm. 

A recent (20 April 2005 through 28 March 2006) full-scale evaluation of 6.35 mm cylindrical 

wedgewire screens was performed at the Eddystone Generating Station located on the Delaware River 

Estuary in Pennsylvania (Veritas et al. 2008). This evaluation supports the applicability of the 

wedgewire performance curve to full scale screens of similar design being considered for IPEC. 

The original cooling water intake structure for Eddystone Units 1 and 2 was located in a shoreline 

bulkhead, and was equipped with conventional 9.5 mm (3/8-inch) mesh traveling screens with no 

design or operational modifications to reduce impingement or entrainment. In the early 1990s, the 

intake for Units 1 and 2 was modified by removing the traveling screens and installing sixteen narrow 

slot cylindrical wedgewire T-type screens (eight per unit). Each wedgewire screen is 72-inch in 

diameter with an effective length of 144 inches (actual overall length is 240 inches including the nose 

cones) and is equipped with 6.35 mm (0.25 inch) wedgewire screening oriented radially around each 

screen with the long axis of the cylinder aligned parallel to the sweeping flow. The average throughscreen velocity is approximately 0.4 feet per second (fps). 

Units 3 and 4 at Eddystone were built after Units 1 and 2, and the cooling water intake structure 

design included several structural modifications specifically to reduce impingement and entrainment. 

Units 3 and 4 employ conventional 9.5 mm (3/8-inch) mesh traveling screens, with a through-screen 

velocity of approximately 0.88 fps at design flow and mean low water level. 

Larvae of tessellated darter (32%), American shad (13%), Cyprinidae (9%), striped bass (9%), white 

perch (7%), Morone spp. (55), and American eel (5%) were the predominant fish taxa observed in 

the entrainment samples collected during a year-long entrainment study performed from April 2005 

through March 2006 at Eddystone Units 1 and 2, with the peak period of entrainment abundance 

occurring from early May through mid-July (Table 2-5 in Veritas et al. 2008). The 6.35 mm slot 

width cylindrical wedgewire screens installed and operated at Units 1 and 2 of Eddystone Generating 

Station were estimated to reduce total annual entrainment of fish eggs and larvae combined by 60% 

from baseline, with a 95% confidence interval of 48 to 71% (Table 5.2, Veritas et al. 2008). In 374 

paired entrainment samples over a full year at Eddystone, the mean density of larvae entrained 

through wedgewire screens at Units 1 and 2 was 82% lower than the mean density of larvae entrained 

simultaneously through conventional 9.5 mm (3/8-inch) mesh screens at Units 3 and 4. These results 

from Eddystone demonstrate that a high percentage of larvae can avoid entrainment through full-scale 

cylindrical wedgewire screens operating under field conditions, even at slot width greater than 6 mm. 

 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 10 Normandeau Associates, Inc.

2.3 REFERENCES

Alden (Alden Research Laboratory, Inc.). 2003. Laboratory study to measure traveling screen 

retention of selected fish species. Prepared for PSEG Services Corporation Estuary 

Enhancement Program. Final Report. 

EA (Ecological Analysts, Inc.). 1977. Preliminary investigations into the use of a continuously 

operating fine mesh traveling screen to reduce ichthyoplankton entrainment at Indian Point 

Generating Station. Prepared for Consolidated Edison Company of New York, Inc. 

EPRI (Electric Power Research Institute). 2003. Laboratory evaluation of wedgewire screens for 

protecting early life stages of fish at cooling water intakes. Report 1005339. 

EPRI (Electric Power Research Institute). 2009. Laboratory evaluation of fine-mesh traveling water 

screens for protecting early life stages of fish at cooling water intakes. Research progress 

update through 2008. Report 1015578. Technical update prepared March 2009 by Alden 

Research Laboratory. 

Fletcher, R.I. 1990. A review of reported fine mesh screen applications for high volume water-intake 

systems, and recommendations for further investigations. Prepared for Consolidated Edison 

Company of New York, Inc. 

Hardy, J.D. Jr. 1978a. Development of fishes of the Mid-Atlantic Bight. An atlas of egg, larval and 

juvenile stages. Vol. 2. Anguillidae through Syngnathidae. U.S. Fish Wildl. Serv. 458 p. 

Hardy, J.D. Jr. 1978b. Development of fishes of the Mid-Atlantic Bight. An atlas of egg, larval and 

juvenile stages. Vol. 3. Aphredoderidae through Rachycentridae. U.S. Fish Wildl. Serv. 

394 p. 

Heuer, J.H., and D.A. Tomljanovich. 1978. A study on the protection of fish larvae at water intakes 

using wedge-wire screening. TVA Tech. Note B26. 60 p. 

Jones, P.W., F.D. Martin, and J.D. Hardy, Jr. 1978. Development of fishes of the Mid-Atlantic 

Bight. An atlas of egg, larval and juvenile stages. Vol. 1. Acipenseridae through Ictaluridae. 

U.S. Fish Wildl. Serv. 366 p. 

Normandeau (Normandeau Associates, Inc.). 1987. Indian Point Generating Station entrainment 

abundance program 1986 annual report. Prepared for Consolidated Edison Company of New 

York, Inc., and New York Power Authority. 

Normandeau (Normandeau Associates, Inc.). 1989. Danskammer Point Station fine mesh screen 

evaluation. 1988 study. Prepared for Central Hudson Gas and Electric Corp. 

Veritas Economic Consulting, Normandeau Associates Inc., and ARCADIS (Veritas et al.) 

December 2008. Development of annual current and baseline impingement mortality and 

entrainment estimates. Eddystone Generating Station. Eddystone, PA. Prepared for Excelon 

Generation Company, LLC 

Weisberg, S.B., W.H. Burton, F. Jacobs, and E.A. Ross. 1987. Reductions in ichthyoplankton 

entrainment with fine-mesh, wedge-wire screens. N. Amer. J. Fish. Manag. 7:386-393. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 11 Normandeau Associates, Inc.

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

4 5 6 7 8 9 10 11 12 13 14 15 16

Total length (mm)

Wedgewire avoidance facto

r

SB/1.0

SB/2.0

BA/1.0

BA/2.0

BA/3.0

Figure 2-1. Observed wedgewire avoidance factors by length, species, and slot width, with 

a generalized relationship between larval length and wedgewire avoidance 

factor. 

Symbols show the data points used to derive the generalized curve Pa = 1 – e [ –0.275 ( L – 4 ) ] (refer to Table 2-7 

for details); SB=striped bass, BA=bay anchovy, labels indicate the wedgewire slot width in millimeters. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 12 Normandeau Associates, Inc.

Table 2-1. Physical exclusion factors for Atlantic tomcod. 

Length 

(mm TL) 

Number 

measured 

Physical exclusion factor Pe by mesh opening width (mm) 

1.0 1.5 2.0 3.0 6.0 9.0 

<5 0 0.00 0.00 0.00 0.00 0.00 0.00 

5 0 0.02 0.00 0.00 0.00 0.00 0.00 

6 26 0.08 0.00 0.00 0.00 0.00 0.00 

7 136 0.26 0.00 0.00 0.00 0.00 0.00 

8 27 0.52 0.15 0.00 0.00 0.00 0.00 

9 0 0.78 0.30 0.00 0.00 0.00 0.00 

10 0 0.95 0.50 0.00 0.00 0.00 0.00 

11 0 1.00 0.70 0.15 0.00 0.00 0.00 

12 1 1.00 0.85 0.30 0.00 0.00 0.00 

13 6 1.00 1.00 0.50 0.00 0.00 0.00 

14 7 1.00 1.00 0.70 0.14 0.00 0.00 

15 11 1.00 1.00 0.85 0.30 0.00 0.00 

16 16 1.00 1.00 1.00 0.50 0.00 0.00 

17 26 1.00 1.00 1.00 0.81 0.00 0.00 

18 28 1.00 1.00 1.00 0.96 0.00 0.00 

19 24 1.00 1.00 1.00 0.92 0.00 0.00 

20 18 1.00 1.00 1.00 0.94 0.00 0.00 

21 24 1.00 1.00 1.00 1.00 0.00 0.00 

22 27 1.00 1.00 1.00 0.96 0.00 0.00 

23 19 1.00 1.00 1.00 0.95 0.00 0.00 

24 16 1.00 1.00 1.00 1.00 0.00 0.00 

25 13 1.00 1.00 1.00 1.00 0.00 0.00 

26 14 1.00 1.00 1.00 1.00 0.00 0.00 

27 8 1.00 1.00 1.00 1.00 0.00 0.00 

28 13 1.00 1.00 1.00 1.00 0.15 0.00 

29 11 1.00 1.00 1.00 1.00 0.18 0.00 

30 7 1.00 1.00 1.00 1.00 0.57 0.00 

31 11 1.00 1.00 1.00 1.00 0.18 0.00 

32 15 1.00 1.00 1.00 1.00 0.53 0.00 

33 15 1.00 1.00 1.00 1.00 0.67 0.00 

34 12 1.00 1.00 1.00 1.00 0.67 0.00 

35 23 1.00 1.00 1.00 1.00 0.83 0.00 

36 25 1.00 1.00 1.00 1.00 0.96 0.00 

37 14 1.00 1.00 1.00 1.00 0.93 0.00 

38 23 1.00 1.00 1.00 1.00 0.96 0.00 

39 20 1.00 1.00 1.00 1.00 1.00 0.00 

40 30 1.00 1.00 1.00 1.00 0.97 0.00 

41 27 1.00 1.00 1.00 1.00 1.00 0.00 

42 33 1.00 1.00 1.00 1.00 1.00 0.03 

43 15 1.00 1.00 1.00 1.00 1.00 0.07 

44 18 1.00 1.00 1.00 1.00 1.00 0.06 

45 18 1.00 1.00 1.00 1.00 1.00 0.11 

46 13 1.00 1.00 1.00 1.00 1.00 0.08 

47 9 1.00 1.00 1.00 1.00 1.00 0.22 

48 10 1.00 1.00 1.00 1.00 1.00 0.50 

49 5 1.00 1.00 1.00 1.00 1.00 0.60 

50 7 1.00 1.00 1.00 1.00 1.00 0.71 

51 5 1.00 1.00 1.00 1.00 1.00 0.80 

52 3 1.00 1.00 1.00 1.00 1.00 0.67 

>52 23 1.00 1.00 1.00 1.00 1.00 1.00 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 13 Normandeau Associates, Inc.

Table 2-2. Physical exclusion factors for striped bass. 

Length 

(mm TL) 

Number 

measured 

Physical exclusion factor Pe by mesh opening width (mm) 

1.0 1.5 2.0 3.0 6.0 9.0 

<4 5 0.00 0.00 0.00 0.00 0.00 0.00 

4 103 0.06 0.00 0.00 0.00 0.00 0.00 

5 943 0.02 0.00 0.00 0.00 0.00 0.00 

6 2,786 0.04 0.00 0.00 0.00 0.00 0.00 

7 2,745 0.26 0.00 0.00 0.00 0.00 0.00 

8 2,583 0.65 0.01 0.00 0.00 0.00 0.00 

9 1,749 0.86 0.07 0.00 0.00 0.00 0.00 

10 798 0.92 0.40 0.01 0.00 0.00 0.00 

11 468 0.98 0.78 0.08 0.00 0.00 0.00 

12 224 1.00 0.95 0.35 0.00 0.00 0.00 

13 117 0.99 0.94 0.77 0.00 0.00 0.00 

14 67 1.00 0.96 0.91 0.00 0.00 0.00 

15 36 1.00 1.00 1.00 0.08 0.00 0.00 

16 21 1.00 0.95 0.81 0.19 0.00 0.00 

17 22 0.95 0.95 0.91 0.41 0.00 0.00 

18 8 1.00 1.00 0.87 0.75 0.00 0.00 

19 7 1.00 1.00 1.00 1.00 0.00 0.00 

20 5 1.00 1.00 1.00 1.00 0.00 0.00 

21 3 1.00 1.00 1.00 1.00 0.00 0.00 

22 1 1.00 1.00 1.00 1.00 0.00 0.00 

23 3 1.00 1.00 1.00 1.00 0.00 0.00 

24 1 1.00 1.00 1.00 1.00 0.00 0.00 

25 4 1.00 1.00 1.00 1.00 0.00 0.00 

26 2 1.00 1.00 1.00 1.00 0.00 0.00 

27 2 1.00 1.00 1.00 1.00 0.05 0.00 

28 2 1.00 1.00 1.00 1.00 0.15 0.00 

29 1 1.00 1.00 1.00 1.00 0.30 0.00 

30 0 1.00 1.00 1.00 1.00 0.50 0.00 

31 0 1.00 1.00 1.00 1.00 0.70 0.00 

32 0 1.00 1.00 1.00 1.00 0.85 0.00 

33 1 1.00 1.00 1.00 1.00 0.95 0.00 

34 0 1.00 1.00 1.00 1.00 1.00 0.00 

35 1 1.00 1.00 1.00 1.00 1.00 0.00 

36 0 1.00 1.00 1.00 1.00 1.00 0.00 

37 0 1.00 1.00 1.00 1.00 1.00 0.00 

38 1 1.00 1.00 1.00 1.00 1.00 0.00 

39 0 1.00 1.00 1.00 1.00 1.00 0.05 

40 0 1.00 1.00 1.00 1.00 1.00 0.15 

41 0 1.00 1.00 1.00 1.00 1.00 0.30 

42 0 1.00 1.00 1.00 1.00 1.00 0.50 

43 0 1.00 1.00 1.00 1.00 1.00 0.70 

44 0 1.00 1.00 1.00 1.00 1.00 0.85 

45 0 1.00 1.00 1.00 1.00 1.00 0.95 

>45 1 1.00 1.00 1.00 1.00 1.00 1.00 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 14 Normandeau Associates, Inc.

Table 2-3. Physical exclusion factors for white perch. 

Length 

(mm TL) 

Number 

measured 

Physical exclusion factor Pe by mesh opening width (mm) 

1.0 1.5 2.0 3.0 6.0 9.0 

<3 3 0.00 0.00 0.00 0.00 0.00 0.00 

3 122 0.01 0.00 0.00 0.00 0.00 0.00 

4 1,189 0.00 0.00 0.00 0.00 0.00 0.00 

5 1,761 0.00 0.00 0.00 0.00 0.00 0.00 

6 1,871 0.01 0.00 0.00 0.00 0.00 0.00 

7 1,410 0.20 0.00 0.00 0.00 0.00 0.00 

8 721 0.64 0.02 0.00 0.00 0.00 0.00 

9 865 0.85 0.09 0.00 0.00 0.00 0.00 

10 1,047 0.94 0.41 0.02 0.00 0.00 0.00 

11 830 0.97 0.78 0.12 0.00 0.00 0.00 

12 640 0.99 0.95 0.49 0.00 0.00 0.00 

13 478 1.00 0.97 0.83 0.01 0.00 0.00 

14 325 0.99 0.97 0.94 0.04 0.00 0.00 

15 217 1.00 0.99 0.96 0.15 0.00 0.00 

16 110 0.99 0.99 0.97 0.45 0.00 0.00 

17 77 1.00 1.00 0.99 0.82 0.00 0.00 

18 44 1.00 1.00 1.00 0.91 0.00 0.00 

19 53 1.00 1.00 1.00 0.96 0.00 0.00 

20 15 1.00 1.00 0.93 0.93 0.00 0.00 

21 16 1.00 1.00 1.00 0.87 0.00 0.00 

22 15 1.00 1.00 1.00 1.00 0.00 0.00 

23 17 1.00 1.00 1.00 0.94 0.00 0.00 

24 11 1.00 1.00 1.00 0.91 0.00 0.00 

25 6 1.00 1.00 1.00 1.00 0.00 0.00 

26 8 1.00 1.00 1.00 0.87 0.12 0.00 

27 4 1.00 1.00 1.00 1.00 0.25 0.00 

28 5 1.00 1.00 1.00 1.00 0.40 0.00 

29 3 1.00 1.00 1.00 1.00 0.33 0.00 

30 2 1.00 1.00 1.00 1.00 0.50 0.00 

31 0 1.00 1.00 1.00 1.00 0.70 0.00 

32 1 1.00 1.00 1.00 1.00 0.85 0.00 

33 2 1.00 1.00 1.00 1.00 0.95 0.00 

34 2 1.00 1.00 1.00 1.00 1.00 0.00 

35 2 1.00 1.00 1.00 1.00 1.00 0.00 

36 2 1.00 1.00 1.00 1.00 1.00 0.00 

37 0 1.00 1.00 1.00 1.00 1.00 0.00 

38 1 1.00 1.00 1.00 1.00 1.00 0.00 

39 0 1.00 1.00 1.00 1.00 1.00 0.05 

40 1 1.00 1.00 1.00 1.00 1.00 0.15 

41 1 1.00 1.00 1.00 1.00 1.00 0.30 

42 3 1.00 1.00 1.00 1.00 1.00 0.50 

43 0 1.00 1.00 1.00 1.00 1.00 0.70 

44 0 1.00 1.00 1.00 1.00 1.00 0.85 

45 4 1.00 1.00 1.00 1.00 1.00 0.95 

>45 16 1.00 1.00 1.00 1.00 1.00 1.00 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 15 Normandeau Associates, Inc.

Table 2-4. Physical exclusion factors for river herring and American shad. 

Length 

(mm TL) 

Number 

measured 

Physical exclusion factor Pe by mesh opening width (mm) 

1.0 1.5 2.0 3.0 6.0 9.0 

<7 286 0.00 0.00 0.00 0.00 0.00 0.00 

7 435 0.01 0.00 0.00 0.00 0.00 0.00 

8 624 0.00 0.00 0.00 0.00 0.00 0.00 

9 699 0.00 0.00 0.00 0.00 0.00 0.00 

10 760 0.03 0.00 0.00 0.00 0.00 0.00 

11 781 0.07 0.00 0.00 0.00 0.00 0.00 

12 844 0.15 0.00 0.00 0.00 0.00 0.00 

13 781 0.33 0.00 0.00 0.00 0.00 0.00 

14 766 0.57 0.01 0.00 0.00 0.00 0.00 

15 629 0.76 0.04 0.00 0.00 0.00 0.00 

16 454 0.88 0.15 0.01 0.00 0.00 0.00 

17 308 0.96 0.39 0.02 0.00 0.00 0.00 

18 208 0.98 0.67 0.03 0.00 0.00 0.00 

19 128 0.98 0.83 0.18 0.00 0.00 0.00 

20 78 0.99 0.96 0.59 0.00 0.00 0.00 

21 46 1.00 1.00 0.89 0.02 0.00 0.00 

22 16 1.00 1.00 0.94 0.06 0.00 0.00 

23 16 1.00 0.94 0.88 0.43 0.00 0.00 

24 19 1.00 1.00 0.90 0.42 0.00 0.00 

25 12 1.00 1.00 0.83 0.50 0.00 0.00 

26 7 1.00 1.00 1.00 0.71 0.00 0.00 

27 4 1.00 1.00 1.00 1.00 0.00 0.00 

28 3 1.00 1.00 1.00 0.67 0.00 0.00 

29 2 1.00 1.00 1.00 1.00 0.05 0.00 

30 3 1.00 1.00 1.00 1.00 0.15 0.00 

31 1 1.00 1.00 1.00 1.00 0.30 0.00 

32 1 1.00 1.00 1.00 1.00 0.50 0.00 

33 1 1.00 1.00 1.00 1.00 0.70 0.00 

34 0 1.00 1.00 1.00 1.00 0.85 0.00 

35 1 1.00 1.00 1.00 1.00 0.95 0.00 

36 0 1.00 1.00 1.00 1.00 1.00 0.00 

37 2 1.00 1.00 1.00 1.00 1.00 0.00 

38 3 1.00 1.00 1.00 1.00 1.00 0.00 

39 1 1.00 1.00 1.00 1.00 1.00 0.05 

40 0 1.00 1.00 1.00 1.00 1.00 0.15 

41 0 1.00 1.00 1.00 1.00 1.00 0.30 

42 0 1.00 1.00 1.00 1.00 1.00 0.50 

43 0 1.00 1.00 1.00 1.00 1.00 0.70 

44 0 1.00 1.00 1.00 1.00 1.00 0.85 

45 0 1.00 1.00 1.00 1.00 1.00 0.95 

>45 3 1.00 1.00 1.00 1.00 1.00 1.00 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 16 Normandeau Associates, Inc.

Table 2-5. Physical exclusion factors for bay anchovy. 

Length 

(mm 

TL) 

Number 

measured 

Physical exclusion factor Pe by mesh opening width (mm) 

1.0 1.5 2.0 3.0 6.0 9.0 

<9 3,582 0.00 0.00 0.00 0.00 0.00 0.00 

9 936 0.01 0.00 0.00 0.00 0.00 0.00 

10 879 0.03 0.00 0.00 0.00 0.00 0.00 

11 859 0.10 0.01 0.00 0.00 0.00 0.00 

12 854 0.24 0.02 0.00 0.00 0.00 0.00 

13 1,063 0.35 0.03 0.01 0.00 0.00 0.00 

14 1,227 0.50 0.07 0.00 0.00 0.00 0.00 

15 1,398 0.71 0.20 0.01 0.00 0.00 0.00 

16 1,372 0.84 0.36 0.03 0.00 0.00 0.00 

17 1,187 0.93 0.55 0.09 0.00 0.00 0.00 

18 889 0.97 0.71 0.20 0.00 0.00 0.00 

19 755 0.99 0.81 0.38 0.00 0.00 0.00 

20 614 1.00 0.88 0.57 0.01 0.00 0.00 

21 427 1.00 0.93 0.74 0.02 0.00 0.00 

22 317 1.00 0.97 0.86 0.11 0.00 0.00 

23 231 1.00 0.98 0.92 0.23 0.00 0.00 

24 163 1.00 1.00 0.94 0.41 0.00 0.00 

25 105 1.00 0.99 0.96 0.73 0.00 0.00 

26 79 1.00 1.00 0.97 0.85 0.00 0.00 

27 52 1.00 1.00 1.00 1.00 0.00 0.00 

28 31 1.00 1.00 1.00 0.94 0.00 0.00 

29 29 1.00 1.00 0.97 0.93 0.00 0.00 

30 12 1.00 1.00 1.00 1.00 0.00 0.00 

31 7 1.00 1.00 1.00 1.00 0.00 0.00 

32 9 1.00 1.00 1.00 1.00 0.00 0.00 

33 5 1.00 1.00 1.00 1.00 0.00 0.00 

34 3 1.00 1.00 1.00 1.00 0.00 0.00 

35 2 1.00 1.00 1.00 1.00 0.05 0.00 

36 0 1.00 1.00 1.00 1.00 0.15 0.00 

37 0 1.00 1.00 1.00 1.00 0.30 0.00 

38 1 1.00 1.00 1.00 1.00 0.50 0.00 

39 1 1.00 1.00 1.00 1.00 0.70 0.00 

40 1 1.00 1.00 1.00 1.00 0.85 0.00 

41 0 1.00 1.00 1.00 1.00 0.95 0.00 

42 1 1.00 1.00 1.00 1.00 1.00 0.00 

43 0 1.00 1.00 1.00 1.00 1.00 0.00 

44 0 1.00 1.00 1.00 1.00 1.00 0.00 

45 0 1.00 1.00 1.00 1.00 1.00 0.00 

46 0 1.00 1.00 1.00 1.00 1.00 0.00 

47 0 1.00 1.00 1.00 1.00 1.00 0.00 

48 0 1.00 1.00 1.00 1.00 1.00 0.00 

49 0 1.00 1.00 1.00 1.00 1.00 0.00 

50 0 1.00 1.00 1.00 1.00 1.00 0.00 

51 0 1.00 1.00 1.00 1.00 1.00 0.05 

52 0 1.00 1.00 1.00 1.00 1.00 0.15 

53 0 1.00 1.00 1.00 1.00 1.00 0.30 

54 0 1.00 1.00 1.00 1.00 1.00 0.50 

55 0 1.00 1.00 1.00 1.00 1.00 0.70 

56 0 1.00 1.00 1.00 1.00 1.00 0.85 

57 0 1.00 1.00 1.00 1.00 1.00 0.95 

>57 0 1.00 1.00 1.00 1.00 1.00 1.00 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 17 Normandeau Associates, Inc.

Table 2-6. Physical exclusion factors for eggs. 

Species 

(reference) 

Egg diameter (mm) Mesh width

Min Max Median SD (mm) Z area Pe

Alewife 

(1) 

0.80 1.27 1.04 0.08 1.0 -0.45 0.174 0.674

1.5 0.000

2.0 0.000

3.0 0.000

6.0 0.000

9.0 0.000

Blueback 

herring 

(1) 

0.87 1.11 0.99 0.04 1.0 0.25 0.099 0.401

1.5 0.000

2.0 0.000

3.0 0.000

6.0 0.000

9.0 0.000

American 

shad 

(1) 

2.50 3.80 3.15 0.22 1.0 1.000

1.5 1.000

2.0 1.000

3.0 -0.69 0.255 0.755

6.0 0.000

9.0 0.000

Bay 

anchovy 

(1) 

0.89 1.30 1.09 0.07 1.0 -1.37 0.415 0.915

1.5 0.000

2.0 0.000

3.0 0.000

6.0 0.000

9.0 0.000

Atlantic 

tomcod 

(2) 

1.39 1.70 1.55 0.05 1.0 1.000

1.5 -0.87 0.308 0.808

2.0 0.000

3.0 0.000

6.0 0.000

9.0 0.000

Striped 

bass 

(3) 

1.30 4.60 2.95 0.55 1.0 1.000

1.5 -2.64 0.496 0.996

2.0 -1.73 0.458 0.958

3.0 0.09 0.036 0.464

6.0 0.000

9.0 0.000

White 

perch 

(3) 

0.65 1.09 0.87 0.07 1.0 1.77 0.462 0.038

1.5 0.000

2.0 0.000

3.0 0.000

6.0 0.000

9.0 0.000
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 18 Normandeau Associates, Inc.

Table 2-7. Data used to fit a generalized curve for estimating wedgewire avoidance 

as a function of length. 

Reference Species 

Slot 

width 

(mm) 

Total 

length 

(mm) 

Wedgewire 

avoidance 

factor (Pa) 

Weisberg et al. (1987) Bay anchovy 1 4 0.000 

Weisberg et al. (1987) Bay anchovy 2 4 0.000 

Weisberg et al. (1987) Bay anchovy 3 4 0.000 

Heuer and Tomljanovich (1978) Striped bass 1 5.75 0.396 

Heuer and Tomljanovich (1978) Striped bass 2 5.75 0.583 

Weisberg et al. (1987) Bay anchovy 1 6 0.427 

Weisberg et al. (1987) Bay anchovy 2 6 0.512 

Weisberg et al. (1987) Bay anchovy 3 6 0.438 

EPRI (2003) Striped bass 1 7.0 0.706 

EPRI (2003) Striped bass 2 8.3 0.464 

Weisberg et al. (1987) Bay anchovy 1 9 0.860 

Weisberg et al. (1987) Bay anchovy 2 9 0.747 

Weisberg et al. (1987) Bay anchovy 3 9 0.662 

Weisberg et al. (1987) Bay anchovy 1 12.5 1.000 

Weisberg et al. (1987) Bay anchovy 2 12.5 0.832 

Weisberg et al. (1987) Bay anchovy 3 12.5 0.769 

Weisberg et al. (1987) Bay anchovy 1 15 0.874 

Weisberg et al. (1987) Bay anchovy 2 15 0.793 

Weisberg et al. (1987) Bay anchovy 3 15 0.839 

Length ranges are represented by the midpoints of the ranges, 4 mm was used to represent the 

≤4 mm category, and 15 mm was used to represent the ≥15 mm category
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 19 Normandeau Associates, Inc.

3.0 IMPINGEMENT MORTALITY OF SMALL FISH ON FINE-MESH INTAKE 

SCREENS AT DANSKAMMER POINT STATION

3.1 APPROACH

Impingement survival studies were conducted at Danskammer Point Generating Station 

(“Danskammer”) during the fall of 1986 (Normandeau 1988a) and during the spring and summer of 

1988 to evaluate the survival of fish impinged on fine mesh traveling screens (Normandeau 1989). 

The results of those Danskammer studies provide one of the few, in-situ tests of size selectivity of full 

scale conventional traveling screens of standard and fine mesh installed and operated at a large 

cooling water intake structure (“CWIS”), and the only full scale study of traveling screen mesh 

selectivity from the Hudson River. Although fish survival from conventional traveling screens of 

either standard or fine mesh are likely to exhibit lower survival than observed from Ristroph traveling 

screens (Fletcher 1990), their mesh selectivity characteristics are applicable to traveling screens of 

similar mesh that have been improved by adding fish handling structures. 

Intuitively, the use of fine mesh traveling screens would be expected to result in increased 

impingement survival of fish by being less abrasive to fish impinged and returned to the source water 

through a spray wash and sluice system compared to standard mesh screens. However, fine mesh 

traveling screens may exhibit higher impingement rates than standard mesh screens because smaller 

fish than would be entrained through a standard mesh screen would be retained on a fine mesh screen, 

increasing the impingement rate when added to the larger fish impinged. Furthermore, recruitment of 

smaller fish to fine mesh screens might also reduce the overall impingement survival rate if the 

smaller fish are more fragile than the older and larger fish that would be impinged on conventional 

mesh screens. The offsetting results of potentially increasing survival of some large fish while 

increasing impingement rates of small fish (which could have lower survival rates than the large fish), 

indicates a need to evaluate empirical and site specific data to compare the mesh selectivity and the 

mortality rates characteristic of fine and standard mesh screens such as the study performed in 1988 at 

Danskammer for applicability to the Indian Point alternative technology assessment. 

Danskammer is located on the west shore of the Hudson River 66 miles upstream from the southern 

tip of Manhattan in New York City. The Unit 3 and Unit 4 CWISs are located in a common intake 

bulkhead at the end of a 450 ft long by 30 ft wide intake canal, with Unit 3 on the east and Unit 4 on 

the west. Unit 3 has two intake pumps, each operating at 41,000 gallons per minute (gpm), for a 

combined maximum intake flow of 82,000 gpm, which enters the CWIS after passing through three 

traveling screens equipped with 3.2 mm square stainless steel mesh. Unit 4 has three intake pumps, 

each operating at 50,000 gpm, for a combined maximum intake flow of 150,000 gpm, which enters 

the CWIS after passing through three traveling screens equipped with 9.5 mm square stainless steel 

mesh. Relatively few fish were impinged during the 1986 study (1,178 fish, both units combined; 

Normandeau 1988a), so this analysis examines the impingement survival and mesh selectivity 

differences between the standard and fine mesh screens from the 1988 study (9,688 fish, both units 

combined). An additional advantage to analyzing the 1988 data is that the spring and summer 

sampling period corresponds to the seasonal presence of fish eggs and larvae of a size that might be 

entrained through the standard mesh screens but impinged on a fine mesh screen. 

Impingement abundance and survival sampling at Danskammer occurred at night on three randomlyselected dates per week beginning 1 May and continuing through 23 August 1988 (Normandeau 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 20 Normandeau Associates, Inc.

1988b). During each 10-hour sampling night, six to thirteen pairs of 30-minute impingement samples 

were simultaneously collected from Unit 3 and Unit 4 in a specially designed survival tank. The Unit 

3 screens were continuously washed at a speed of one revolution per five minutes during 

impingement survival sample collections, and the Unit 4 screens were continuously washed at a speed 

of one revolution every ten minutes. All fish and blue crabs collected were classified as alive, 

stunned, or dead at the time of initial collection (time 0, or “initial survival”), and then all live and 

stunned fish were held for subsequent latent survival observations at 2.5, 8, 12, 24, 48, and 96 hours 

after initial collection. The survival tests were terminated after 96 hours, and all fish in each survival 

class (alive, stunned, and dead) were preserved as separate samples from each test in 10% buffered 

formalin and later examined to determine and enumerate each species, and to measure the length 

(millimeters total length) and weight (nearest 0.1 gram) of each individual. 

The original data files from the 1988 Danskammer study were restored to modern digital media and 

reanalyzed to calculate survival for each species (and for all taxa combined) and length class from the 

fine mesh and standard mesh traveling screens. In the original analysis, stunned fish were considered 

alive; however stunned fish were reclassified and considered dead in this re-analysis to provide a 

more conservative estimate of survival and one consistent with Fletcher (1990). Unfortunately, to 

minimize handling stress, alive and stunned fish in the Danskammer study were not measured for 

length until the 96-hour observation period when they were placed in preservative and taken to the 

laboratory for length measurement. Therefore, it was not possible to re-evaluate survival by length 

class for individual fish taxa or for all fish taxa combined at intermediate survival observation 

intervals such as the 8-hour interval used for the Indian Point Ristroph screen survival studies 

(Fletcher 1990). Accordingly, the results of this re-analysis are based on the initial (time 0) and latent 

(time 96 hours) observations. 

An illustration of the relationship between initial, intermediate, and latent survival is shown for 

abundant fish taxa and for all fish taxa combined (total) in Table 3-1. It is apparent from the data in 

Table 3-1 that there is some additional mortality occurring beyond the eight-hour observation interval 

that makes the 96-hour latent survival values conservatively high. The Danskammer study attempted 

to obtain and test control fish to adjust the survival data presented in Table 3-1. However the 

collection methods (seining and trawling) were too harsh, resulting in poor survival of the control 

fish, and consequently the inability to use these data to calculate control adjusted survival. 

Size selectivity of the fine mesh (Unit 3) and standard mesh (Unit 4) conventional traveling screens at 

Danskammer was evaluated by examining the adjusted length frequency distributions of the fish 

collected from each unit. Adjusted length frequency distributions were based on the density of fish 

(number per unit volume of intake flow sampled by taxon or all taxa combined) caught in each 10 

mm length class scaled to adjust for the lower CWIS flow rate inherent in the design of Unit 3 (based 

on n=1,813 fish measured) compared to Unit 4 (based on n=7,720 fish measured). Fish densities for 

Unit 3 were scaled upward by multiplying by a factor of 1.7570 to account for the lower intake flow 

actually sampled at Unit 3 (3,884,346 m3

) compared to Unit 4 (6,824,822 m3). It is clear that this 

factor compares closely to the ratio of differences in design intake flow for Unit 4 compared to Unit 3 

(150,000 gpm/82,000 gpm = 1.8290), indicating both units sampled at nearly the same as their rated 

capacity during the 1988 study. 

Size selectivity of the fine mesh traveling screens was apparent in the adjusted length frequency 

distributions for the fine mesh and standard mesh screens (Figures 3-1 through 3-3). The fine mesh 

screens of Unit 3 impinged more fish (Figure 3-1) and a greater proportion of fish (Figure 3-2) below 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 21 Normandeau Associates, Inc.

50 mm (total length) than the standard mesh screens of Unit 4. The 20-29 mm length class comprised 

the greatest proportion of fish impinged at Unit 3 and the 50-59 mm length class comprised the 

greatest proportion of fish impinged at Unit 4 (Figure 3-2). Comparing the cumulative relative length 

frequency distributions (Figure 3-3) also suggested that there was some avoidance, escapement or 

loss of larger fish in the 60 mm to 140 mm length classes from the fine mesh screens of Unit 3, 

because the two cumulative frequency distributions converged at 140 mm and well above the 

retention size for the standard mesh screens of Unit 4. Avoidance or escapement from the fine mesh 

screens may be related to differences in approach velocity relative to the size of the fish impinged 

(EPRI 2003), resulting in the larger fish exposed to the fine mesh screens at Unit 3 being more 

capable of avoiding impingement by swimming away because of the slower approach velocity 

compared to Unit 4, so that the difference between size distributions between the two units was 

probably not related to mesh selectivity. 

Differences in the number and proportion of fish impinged in the larger length classes between the 

standard and fine mesh screens in this Danskammer study, even though both units were sampling the 

same source water body in simultaneous and paired collections, suggests the data cannot be pooled 

into one composite size frequency distribution to determine selectivity for application to Indian Point. 

To further examine the differences in mesh selectivity and survival of the portion of fish impinged on 

the fine mesh screens at Danskammer Unit 3 but of a size expected to be entrained through the 

standard mesh screens at Unit 4, the total length corresponding to the median (50%) limiting body 

dimensions of the selected, abundant taxa (Section 2.1) were used to classify the fish into two size 

classes: 

Class 1 = small fish of a length with median (50%) greatest body depth less than or 

equal to 9.5 mm that would be retained on the fine mesh but entrained through the 

standard mesh, and 

Class 2 = large fish of a length with median (50%) greatest body depth larger than 9.5 

mm that would be impinged on both the fine mesh and standard mesh. 

The following fish total length dimensions were used to classify the Danskammer impingement 

collections into small (Class 1) and large (Class 2) size categories based on the median 50% greatest 

body depth: 

Fish Taxon Class 1 Total Length (mm) Class 2 Total Length (mm) 

Bay anchovy <54 >54 

Striped bass <42 >42 

White perch <42 >42 

Clupeids <42 >42 

All others <42 >42 

3.2 RESULTS

3.2.1 Bay Anchovy 

Nearly all (97%; n = 235) of the 246 bay anchovy retained on the fine mesh screens of Danskammer 

Unit 3 and measured for length were less than 54 mm total length (Length Class 1), while only 37% 

(n = 17) of the 46 bay anchovy caught and measured from the standard mesh screens of Unit 4 were 

of this small size (Table 3-2). These observations suggest that about two-thirds of the bay anchovy of 

the size retained on the fine mesh screens would have been entrained through the standard mesh 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 22 Normandeau Associates, Inc.

screen. If avoidance is considered comparable for the small, Length Class 1 bay anchovy in the 

combined impingement collections from Unit 3 and Unit 4 of Danskammer, and both Units are 

considered sampling the same source population, then 93% of the bay anchovy less than 54 mm total 

length were retained on the 3.2 mm fine mesh conventional traveling screens compared to just 7% for 

the standard 9.5 mm mesh conventional traveling screens (Table 3-3). Low initial (time 0) survival of 

the total catch of bay anchovy on both standard and fine mesh screens (Tables 3-4, 3-5, and 3-6), 

compounded with low numbers from Unit 4, indicate that both fine mesh and standard mesh screens 

tested at Danskammer exhibited extremely low survival for bay anchovy, particularly when compared 

to the survival for this species from the fish conservation Ristroph traveling screens and a state of the 

art fish return system like the one presently installed and operated at Indian Point (Table 3-7; Fletcher 

1990). 

3.2.2 Striped Bass 

Nearly all (94%; n = 381) of the 404 striped bass retained on the fine mesh screens of Danskammer 

Unit 3 and measured for length were less than 42 mm total length (Length Class 1), while nearly all 

(82%; n = 223) of the 272 striped bass caught and measured from the standard mesh screens of Unit 4 

were large fish in Length Class 2 (Table 3-2). These observations suggest that most striped bass of 

the size retained on the fine mesh screens would have been entrained through the standard mesh 

screen. If avoidance is considered comparable for the small, Length Class 1 striped bass in the 

combined impingement collections from Unit 3 and Unit 4 of Danskammer, and both Units are 

considered sampling the same source population, then 89% of the striped bass less than 42 mm total 

length were retained on the 3.2 mm fine mesh conventional traveling screens compared to just 11% 

for the standard 9.5 mm mesh conventional traveling screens (Table 3-3). 

The initial (time 0) survival of the striped bass less than 42 mm total length impinged on both 

standard and fine mesh screens were nearly identical (34% at Unit 3 vs. at 35% Unit 4; Table 3-5), 

while the extended (time 96) survival of these Length Class 1 fish was higher for the fine mesh screen 

(17%) compared to the standard mesh screen (8%). The initial (time 0) survival rates of the striped 

bass greater than or equal to 42 mm total length impinged on both standard and fine mesh screens 

were also nearly identical (77% Unit 3 vs. 75% unit 4; Table 3-6), while the extended (time 96) 

survival of these Length Class 1 fish was higher for the fine mesh screens (39%) compared to the 

standard mesh screens (11%). The absolute survival was higher for striped bass impinged on fish 

conservation traveling screens and a state of the art fish return system like the one presently installed 

and operated at Indian Point (Table 3-7; Fletcher 1990), and the results from the Danskammer fine 

mesh impingement study suggest that comparable or higher survival could be achieved for the small 

fish of a size that would be entrained through the standard mesh screens but retained on a 3.2 mm fine 

mesh traveling screens. 

3.2.3 White Perch 

Slightly more than half (55%; n = 529) of the 956 white perch retained on the fine mesh screens of 

Danskammer Unit 3 and measured for length were less than 42 mm total length (Length Class 1), 

while nearly all (95%; n = 3,243) of the 3,420 white perch caught and measured from the standard 

mesh screens of Unit 4 were large fish in Length Class 2 (Table 3-2). These observations suggest that 

most white perch of the size retained on the fine mesh screens would have been entrained through the 

standard mesh screen. If avoidance is considered comparable for the small, Length Class 1 white 

perch in the combined impingement collections from Unit 3 and Unit 4 of Danskammer, and both 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 23 Normandeau Associates, Inc.

Units are considered sampling the same source population, then 75% of the white perch less than 42 

mm total length were retained on the 3.2 mm fine mesh conventional traveling screens compared to 

25% for the standard 9.5 mm mesh conventional traveling screens (Table 3-3). 

The initial (time 0) survival of the white perch less than 42 mm total length impinged on the fine 

mesh screens of Unit 3 was lower (18%) compared to the standard mesh screens on Unit 4 (44%; 

Table 3-5). The extended (time 96) survival of these Length Class 1 white perch was higher for the 

fine mesh screen (12%) compared to the standard mesh screen (5%; Table 3-5). The initial (time 0) 

survival of the white perch greater than or equal to 42 mm total length impinged on the fine mesh 

screens was also lower (53%) compared to the standard mesh screens on Unit 4 (87%; Table 3-6), 

while the extended (time 96) survival of these Length Class 1 fish was comparable for both screens 

(22% at Unit 3 vs. 19% at Unit 4; Table 3-6). The absolute survival was higher for white perch 

impinged on fish conservation Ristroph traveling screens and a state of the art fish return system like 

the one presently installed and operated at Indian Point (Table 3-7; Fletcher 1990), and the results 

from the Danskammer fine mesh impingement study suggest that comparable or lower survival could 

be achieved for the small fish of a size that would be entrained through the standard mesh screens but 

retained on a 3.2 mm fine mesh traveling screens. 

3.2.4 Clupeids 

Nearly two-thirds (63%; n = 754) of the 1,189 clupeids retained on the fine mesh screens of 

Danskammer Unit 3 and measured for length were less than 42 mm total length (Length Class 1), 

while nearly all (96%; n = 2,622) of the 2,732 clupeids caught and measured from the standard mesh 

screens of Unit 4 were large fish greater than or equal to 42 mm total length in Length Class 2 (Table 

3-2). These observations suggest that most clupeids of the size retained on the fine mesh screens 

would have been entrained through the standard mesh screen. If avoidance is considered comparable 

for the small, Length Class 1 clupeids in the combined impingement collections from Unit 3 and Unit 

4 of Danskammer, and both Units are considered sampling the same source population, then 87% of 

the clupeids less than 42 mm total length were retained on the 3.2 mm fine mesh conventional 

traveling screens compared to just 13% for the standard 9.5 mm mesh conventional traveling screens 

(Table 3-3). Low initial (time 0) survival of the total catch of clupeids on both standard and fine 

mesh screens (Tables 3-4, 3-5, and 3-6), indicates that these fragile fish do not survive well from 

either fine mesh or standard mesh traveling screens at Danskammer compared to fish conservation 

Ristroph traveling screens and a state of the art fish return system like the one presently installed and 

operated at Indian Point (Table 3-7; Fletcher 1990). 

3.2.5 All Other Fish Taxa 

Slightly more than half (54%; n = 211) of the 394 fish of 22 taxa comprising the all other fish taxa 

category retained on the fine mesh screens of Danskammer Unit 3 and measured for length were less 

than 42 mm total length (Length Class 1), while nearly all (94%; n = 1,171) of the 1,250 all other fish 

taxa caught and measured from the standard mesh screens of Unit 4 were large fish in Length Class 2 

(Table 3-2). These observations suggest that most of the all other fish taxa of the size retained on the 

fine mesh screens would have been entrained through the standard mesh screen. If avoidance is 

considered comparable for the small, Length Class 1 all other fish taxa in the combined impingement 

collections from Unit 3 and Unit 4 of Danskammer, and both Units are considered sampling the same 

source population, then 73% of the these fish less than 42 mm total length were retained on the 3.2 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 24 Normandeau Associates, Inc.

mm fine mesh conventional traveling screens compared to 27% for the standard 9.5 mm mesh 

conventional traveling screens (Table 3-3). 

The initial (time 0) survival of the all other fish taxa less than 42 mm total length impinged on the 

fine mesh screens of Unit 3 was lower (45%) compared to the standard mesh screens on Unit 4 (82%; 

Table 3-5). The extended (time 96) survival of these Length Class 1 all other fish taxa for the fine 

mesh screen (38%) remained slightly more than half of the latent survival for the standard mesh 

screen (71%; Table 3-5). The initial (time 0) survival of the all other fish taxa greater than or equal to 

42 mm total length impinged on the fine mesh screens was also lower (67%) compared to the 

standard mesh screens on Unit 4 (93%; Table 3-6), and the extended (time 96) survival of these 

Length Class 2 fish remained lower for the fine mesh screens (49% Unit 3 vs. 61% Unit 4; Table 3-6). 

The absolute survival was higher for all other fish taxa impinged on fish conservation traveling 

screens and a state of the art fish return system like the one presently installed and operated at Indian 

Point (Fletcher 1990), and the results from the Danskammer fine mesh impingement study suggest 

that comparable or lower survival could be achieved for the small fish of a size that would be 

entrained through the standard mesh screens but retained on a 3.2 mm fine mesh traveling screens. 

3.2.6 All Fish Taxa Combined 

Ignoring the differences in survival by fragile and hardy fish species identified by taxon in the 

Danskammer study, examination of the entire fish community sampled during the 1988 study 

revealed that two-thirds (66%; n = 2,110) of the 3,185 fish in the aggregate community of small fish 

represented by Length Class 1 were retained on the fine mesh screens of Danskammer Unit 3 and 

measured for length (Table 3-2). Nearly all (94%; n = 7,288) of the 7,720 fish caught and measured 

from the standard mesh screens of Unit 4 were large fish in Length Class 2 (Table 3-2). These 

observations suggest that most of the fish of the size retained on the fine mesh screens would have 

been entrained through the standard mesh screen. If avoidance is considered comparable for the 

small, Length Class 1 fish in the combined impingement collections from Unit 3 and Unit 4 of 

Danskammer, and both Units are considered sampling the same source population, then 83% of the 

small fish in Length Class 1were retained on the 3.2 mm fine mesh conventional traveling screens 

compared to just 17% for the standard 9.5 mm mesh conventional traveling screens (Table 3-3). 

The all fish taxa combined category exhibited a relatively low initial (time 0) survival (17%; n = 357) 

of the 2,110 small fish represented by Length Class 1 that were impinged on the fine mesh screens of 

Unit 3 compared to 37% initial survival for Length Class 1 fish impinged on the standard mesh 

screens of Unit 4 (160 fish out of 432 total fish = 37%; Table 3-5). The extended (time 96) survival 

of these Length Class 1 fish was also lower for the fine mesh screen (10%) compared to the standard 

mesh screen (16%; Table 3-5). The initial (time 0) survival of the all fish taxa combined category of 

larger Length Class 2 fish impinged on the fine mesh screens was also lower (45%) compared to the 

standard mesh screens on Unit 4 (59%; Table 3-6), while the extended (time 96) survival of these 

Length Class 2 fish was comparable for both screens (18% Unit 3 vs. 18% Unit 4; Table 3-6). The 

absolute survival was higher for all fish taxa (combined) impinged on fish conservation traveling 

screens and a state of the art fish return system like the one presently installed and operated at Indian 

Point (Fletcher 1990), and the results from the Danskammer fine mesh impingement study suggest 

that comparable survival could be achieved for the small fish of a size that would be entrained 

through the standard mesh screens but retained on a 3.2 mm fine mesh traveling screens. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 25 Normandeau Associates, Inc.

3.3 REFERENCES

EPRI (Electric Power Research Institute). 2000. Technical evaluation of the utility of intake 

approach velocity as an indicator of potential adverse environmental impact under Clean 

Water Act Section 316(b). Report 1000731. 

Fletcher, R.I. 1990. Flow dynamics and fish recovery experiments: water intake systems. 

Transactions of the American Fisheries Society 119: 393-415. 

Normandeau (Normandeau Associates, Inc.). 1988a. Danskammer Point Station fine mesh screen 

evaluation – 1986 study. Prepared for Central Hudson Gas and Electric Corporation. 

Normandeau (Normandeau Associates, Inc.). 1988b. Standard operating procedures for the 

1986/1988 Danskammer Point Station fine mesh screen evaluation. Prepared for Central 

Hudson Gas and Electric Corporation. 

Normandeau (Normandeau Associates, Inc.). 1989. Danskammer Point Station fine mesh screen 

evaluation – 1988 Study. Prepared for Central Hudson Gas and Electric Corporation. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 26 Normandeau Associates, Inc.

Figure 3-1. Adjusted (for differences in volume sampled) length frequency distributions for 

fish impinged on the 3.2 mm fine mesh conventional traveling screens at 

Danskammer Unit 3 and the 9.5 mm standard mesh conventional traveling 

screens at Unit 4, 1 May through 23 August 1988. 

Unit 3

Unit 4

Adjusted Count

 0

 200

 400

 600

 800

 1,000

 1,200

 1,400

 1,600

 1,800

 2,000

 2,200

Length

10-19 mm20-29 mm30-39 mm40-49 mm50-59 mm60-69 mm70-79 mm80-89 mm90-99 mm

100-109 mm110-119 mm120-129 mm130-139 mm140-149 mm150-159 mm160-169 mm170-179 mm180-189 mm190-199 mm

200 + mm
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 27 Normandeau Associates, Inc.

Figure 3-2. Relative (percent) adjusted length frequency distributions for fish impinged on 

the 3.2 mm fine mesh conventional traveling screens at Danskammer Unit 3 

and the 9.5 mm standard mesh conventional traveling screens at Unit 4, 1 May 

through 23 August 1988. 

Unit 3

Unit 4

Relative (Percent) Frequency

0

10

20

30

40

50

60

70

80

90

100

Length

10-19 mm20-29 mm30-39 mm40-49 mm50-59 mm60-69 mm70-79 mm80-89 mm90-99 mm

100-109 mm110-119 mm120-129 mm130-139 mm140-149 mm150-159 mm160-169 mm170-179 mm180-189 mm190-199 mm

200 + mm
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 28 Normandeau Associates, Inc.

Figure 3-3. Cumulative relative length frequency distributions for fish impinged on the 3.2 

mm fine mesh conventional traveling screens at Danskammer Unit 3 and the 

9.5 mm standard mesh conventional traveling screens at Unit 4, 1 May through 

23 August 1988. 

Unit 3

Unit 4

Cumulative Relative(Percent) Frequency

0

10

20

30

40

50

60

70

80

90

100

Length

10-19 mm20-29 mm30-39 mm40-49 mm50-59 mm60-69 mm70-79 mm80-89 mm90-99 mm

100-109 mm110-119 mm120-129 mm130-139 mm140-149 mm150-159 mm160-169 mm170-179 mm180-189 mm190-199 mm

200 + mm
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 29 Normandeau Associates, Inc.

Table 3-1. Results of the Danskammer fine mesh traveling screen impingement 

survival study, 1 May – 23 August 1988. (Unit 3 = 3.2 mm fine mesh, Unit 4 

= 9.5 mm standard mesh). 

Fish Taxon Unit 

Total 

Number 

Collected 

Number Dead

at 0 Hours 

Number Held

for 96 Hours 

Total Percent Alive at Observation Time in Hours 

0 2.5 8 12 24 48 96 

Bay anchovy 

3 137 134 3 0.7% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 

4 45 45 0 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 

Striped bass 

3 226 141 85 32.3% 25.7% 23.9% 23.5% 23.0% 21.2% 19.0%

4 276 87 189 43.8% 40.9% 31.9% 29.7% 24.3% 16.7% 10.5%

White perch 

3 544 357 187 23.5% 22.1% 20.2% 20.0% 19.1% 17.1% 16.9%

4 3474 516 2958 41.8% 40.3% 36.6% 35.8% 31.1% 23.0% 18.0%

Clupeids 3 679 591 88 2.5% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0%

4 2754 2551 203 0.7% 0.5% 0.5% 0.2% 0.2% 0.2% 0.0% 

All others 

3 236 100 136 48.7% 48.7% 49.2% 48.3% 47.5% 45.8% 41.9%

4 1317 96 1221 74.4% 73.7% 73.1% 73.7% 72.9% 67.7% 59.6%

Total 3 1822 1323 499 18.3% 16.1% 15.4% 15.1% 14.7% 13.7% 12.8%

4 7866 3295 4571 32.7% 31.8% 29.7% 29.2% 26.9% 22.1% 18.3%
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 30 Normandeau Associates, Inc.

Table 3-2. Number and percent of fish collected in Length Class 1 (representing the 

fraction of small fish retained on the fine mesh screen of Unit 3 but not on 

the standard mesh screen of Unit 4) and Length Class 2 (representing the 

fraction of large fish retained on both the fine mesh and standard mesh 

screens) for which length was determined, adjusted for differences in 

intake flow between Danskammer Point Station Unit 3 and Unit 4, 1 May – 

23 August 1988. (Unit 3 = 3.2 mm fine mesh, Unit 4 = 9.5 mm standard 

mesh). 

Fish Taxon Unit 

Number of Fish Measured 

Percent Caught by 

Length Class 

All Fish 

Caught 

Length 

Class 1 

Length 

Class 2 

Length 

Class 1 

Length 

Class 2 

Bay anchovy 3 242 235 7 97.1% 2.9%

4 46 17 29 37.0% 63.0%

Striped bass 3 404 381 23 94.3% 5.7%

4 272 49 223 18.0% 82.0%

White perch 3 956 529 427 55.3% 44.7%

4 3,420 177 3,243 5.2% 94.8%

Clupeids 3 1,189 754 436 63.4% 36.7%

4 2,732 110 2,622 4.0% 96.0%

All other taxa 3 394 211 183 53.6% 46.4%

4 1,250 79 1,171 6.3% 93.7%

All taxa 3 3,185 2,110 1,075 66.2% 33.8%

4 7,720 432 7,288 5.6% 94.4%
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 31 Normandeau Associates, Inc.

Table 3-3. Number and percent of fish collected in Length Class 1 (representing the 

fraction of small fish retained on the fine mesh screen of Unit 3 but not on 

the standard mesh screen of Unit 4) that contributed to the combined 

impingement collection from both Units, adjusted for differences in intake 

flow between Danskammer Point Station Unit 3 and Unit 4, 1 May – 23 

August 1988. (Unit 3 = 3.2 mm fine mesh, Unit 4 = 9.5 mm standard mesh). 

Fish Taxon Unit 

Number in 

Length Class 1 

Percent in 

Length Class 1 

Bay anchovy 

 

3 235 93.3%

4 17 6.7%

Both 252 100.0%

Striped bass 

 

3 381 88.6%

4 49 11.4%

Both 430 100.0%

White perch 

 

3 529 74.9%

4 177 25.1%

Both 706 100.0%

Clupeids 

 

3 754 87.3%

4 110 12.7%

Both 864 100.0%

All other taxa 

 

3 211 72.8%

4 79 27.2%

Both 290 100.0%

All taxa 

 

3 2,110 83.0%

4 432 17.0%

Both 2,542 100.0%
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 32 Normandeau Associates, Inc.

Table 3-4. Number of fish and percent impingement survival for all fish for which 

length was determined, adjusted for differences in intake flow between 

Danskammer Point Station Unit 3 and Unit 4, 1 May – 23 August 1988. 

(Unit 3 = 3.2 mm fine mesh, Unit 4 = 9.5 mm standard mesh). 

Fish Taxon Unit 

All Fish Regardless of Size Class 

Number of Fish Percent Alive 

Alive 

Time 0 

Alive 

Time 96 

All Fish 

Caught 

Time 0 Time 96 

% SE % % SE % 

Bay anchovy 3 2 0 242 0.7 0.5 0.0 

4 0 0 46 0.0 0.0 

Striped bass 3 148 76 404 36.5 2.4 18.7 1.9

4 185 29 272 68.0 2.8 10.7 1.9

White perch 3 322 158 956 33.6 1.5 16.5 1.2

4 2,906 618 3,420 85.0 0.6 18.1 0.7

Clupeids 3 156 0 1,189 13.1 1.0 0.0 

4 208 0 2,732 7.6 0.5 0.0 

All other taxa 3 218 170 394 55.4 2.5 43.3 2.5

4 1,150 769 1,250 92.0 0.8 61.5 1.4

All taxa 3 845 404 3,185 26.5 0.8 12.7 0.6

4 4,449 1,416 7,720 57.6 0.6 18.3 0.4
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 33 Normandeau Associates, Inc.

Table 3-5. Number of fish and percent impingement survival for Length Class 1 

representing the fraction of small fish retained on the fine mesh screen 

(Unit 3) but not on the standard mesh screen (Unit 4) for which length was 

determined, adjusted for differences in intake flow between Danskammer 

Point Station Unit 3 and Unit 4, 1 May – 23 August 1988. (Unit 3 = 3.2 mm 

fine mesh, Unit 4 = 9.5 mm standard mesh). 

Fish Taxon Unit 

Small Fish Retained on Fine Mesh But Not On Standard Mesh 

(Length Class 1) 

Number of Fish Percent Alive 

Alive 

Time 0 

Alive 

Time 96 

All Fish 

Caught 

Time 0 Time 96 

% SE % % SE % 

Bay 

anchovy 

3 2 0 235 0.7 0.6 0.0 

4 0 0 17 0.0 0.0 

Striped bass 3 130 67 381 34.1 2.4 17.5 1.9

4 17 4 49 34.7 6.8 8.2 3.9

White perch 3 93 65 529 17.6 1.7 12.3 1.4

4 78 9 177 44.1 3.7 5.1 1.7

Clupeids 3 37 0 754 4.9 0.8 0.0 

4 0 0 110 0.0 0.0 

All other 

taxa 

3 95 81 211 45.0 3.4 38.3 3.3

4 65 56 79 82.3 4.3 70.9 5.1

All taxa 3 357 213 2,110 16.9 0.8 10.1 0.7

4 160 69 432 37.0 2.3 16.0 1.8
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 34 Normandeau Associates, Inc.

Table 3-6. Number of fish and percent impingement survival for Length Class 2 

representing the fraction of large fish retained on both the fine mesh and 

standard mesh screens for which length was determined, adjusted for 

differences in intake flow between Unit 3 and Unit 4, 1 May – 23 August 

1988. (Unit 3 = 3.2 mm fine mesh, Unit 4 = 9.5 mm standard mesh). 

Fish Taxon Unit 

Large Fish Retained on both Fine Mesh and Standard Mesh 

(Length Class 2) 

Number of Fish Percent Alive 

Alive 

Time 0 

Alive 

Time 96 

All Fish 

Caught 

Time 0 Time 96 

% SE % % SE % 

Bay anchovy 3 0 0 7 0.0 0.0 

4 0 0 29 0.0 0.0 

Striped bass 3 18 9 23 76.9 8.8 38.5 10.2

4 168 25 223 75.3 2.9 11.2 2.1

White perch 3 228 93 427 53.5 2.4 21.8 2.0

4 2,828 609 3,243 87.2 0.6 18.8 0.7

Clupeids 3 119 0 436 27.4 2.1 0.0 

4 208 0 2,622 7.9 0.5 0.0 

All other taxa 3 123 90 183 67.3 3.5 49.0 3.7

4 1,085 713 1,171 92.7 0.8 60.9 1.4

All taxa 3 488 192 1,075 45.4 1.5 17.8 1.2

4 4,289 1,347 7,288 58.9 0.6 18.5 0.5
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 35 Normandeau Associates, Inc.

Table 3-7. Comparison of 8-hour survival (percent alive) and the total number of fish 

collected (N Total) for common fish impinged on the Danskammer Point 

Station fine mesh conventional traveling screens at Unit 3 (3.2 mm), the 

standard mesh traveling screens at Unit 4 (9.5 mm) tested between 1 May 

and 23 August 1988, and the Ristroph screen version 2 installed and 

tested at Indian Point Unit 2, screen well 26 during 16 September through 

24 October 1986. 

Taxon 

Danskammer Indian Point Ristroph1

Unit 3 Fine Mesh Unit 4 Standard Mesh Unit 2 

N Total % Alive N Total % Alive N Total % Alive 

Bay anchovy 137 0.0% 45 0.0% 1,060 77%

Striped bass 226 23.9% 276 31.9% 86 91%

White perch 544 20.2% 3,474 36.6% 1,806 86%

American shad 51 0.0% 724 0.0% 169 65%

Blueback herring 183 0.0% 1,598 0.8% 277 74%

1

Data source: Fletcher (1990) Table 4 cumulative dead and injured after 8 hours. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 36 Normandeau Associates, Inc.

4.0 LOVETT GUNDERBOOM EFFECTIVENESS AND MESH SELECTIVITY 

ANALYSIS

4.1 APPROACH

The AFB is a relatively new fish protection technology for use at CWISs to meet Clean Water Act 

§316(b) performance requirements (EPA 2004). While the AFB is permeable to water, it is relatively 

impermeable to fish, shellfish, and ichthyoplankton and, therefore, is one of only a few technologies 

capable of reducing both impingement and entrainment of aquatic organisms (EPA 2004). 

Gunderboom has a patented full-water-depth filter curtain composed of polyethylene or 

polypropylene fabric panels that is supported by flotation billets at the surface of the water and 

anchored to the bottom of the water body (LMS 1998b, 2005). This AFB system is referred to as the 

Gunderboom Marine Life Exclusion SystemTM (Gunderboom MLESTM). The Gunderboom MLESTM 

completely surrounds a CWIS, preventing organisms from entering the intake. Since the surface area 

of an MLESTM is large compared to the surface area of the intake structure’s traveling screens, 

through-screen water velocity can be reduced to below 0.5 fps, thereby enabling even small fish and 

larvae to swim or drift away from the filter curtain. 

The engineering performance of a Gunderboom MLESTM was evaluated at Lovett Generating Station 

(“Lovett”) in each year 1994 through 2002 with the objectives of designing, installing and testing a 

full scale system that could be installed and reliably operated at Lovett Station to exclude fish eggs 

and larvae from entrainment into Lovett’s cooling water intake system (CWIS) (LMS 1996, 1997, 

1998a, 1998b, 2005). Biological effectiveness testing began in 2003 with an evaluation of sampling 

methodology and techniques (ASA 2003), followed by four consecutive years of complete seasonal 

sampling from May through October of 2004, 2005, 2006, and 2007 (ASA 2004, 2005, 2006, 2007). 

Lovett ceased operation in 2008 and was dismantled. 

Lovett consisted of three fossil-fueled, steam electric units (Units 3, 4, and 5) having net generating 

capacities of 63 megawatts of electric power (MWe), 197 MWe, and 202 MWe, respectively, for a 

total of 463 MWe for all three units combined. The once through design cooling water intake flows 

were 42,000 gpm for Unit 3, 104,300 gpm for Unit 4, and 112,000 gpm for Unit 5, for a total of 

258,300 gpm. Cooling water for each of the three Lovett units was withdrawn from the Hudson River 

estuary through shoreline intakes equipped with conventional 3/8-inch mesh traveling screens. The 

AFB installed and tested at Lovett was made from two layers of non-woven fabric (LMS 1998b) that 

encircled the shoreline bulkhead containing the CWISs for Unit 3, Unit 4, and Unit 5. The outer layer 

had 0.5 mm diameter perforations spaced on-center at 6.4 mm, and the inner layer was vented with 

horizontal 5.1 cm flaps spaced at 0.6 m (LMS 1998b). 

Biological effectiveness was determined by comparing the percent difference in density of 

entrainment-sized ichthyoplankton from pairs of pumped samples collected inside and outside of a 

deployed AFB enclosing the Lovett CWIS. Lovett Station was located on the west bank of the 

Hudson River estuary just north of Stony Point, New York, 41 miles upstream from the southern tip 

of Manhattan in New York City. Lovett was slightly downstream and almost directly across the 

Hudson River from Indian Point, which is located on the east bank at mile point 42. Accordingly, 

both Lovett and Indian Point are exposed to the same source water body population of 

ichthyoplankton during the same seasonal cycle and are likely to experience similar entrainment into 
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Appendix B 2-1-10.DOC, 2/2/10 37 Normandeau Associates, Inc.

the CWISs of each plant. Therefore, the Gunderboom system tested at Lovett Station was considered 

a likely surrogate for the effectiveness and selectivity of a similar system if designed, installed and 

operated at Indian Point as an alternative technology for impingement and entrainment mitigation. 

4.2 RESULTS

The four reports regarding the biological effectiveness of the AFB evaluated at Lovett (ASA 2004, 

2005, 2006, and 2007) describe the sampling designs and methods specified in the project-specific 

Standard Operating Procedures (LMS 2005). These Standard Operating Procedures, which assured 

consistency of methods among years, are briefly summarized in this report. Five pairs of 

ichthyoplankton samples of an average volume of about 70 m3

 each were collected during two nights 

per week by pumping for 60-75 minutes at 200-240 gpm in the protected (from entrainment) water on 

the intake side of the deployed AFB and in an adjacent area outside of the AFB beginning in May and 

continuing through August of each year. One night was sampled every other week from early 

September through mid-October of each year. The samples from the intake side of the deployed AFB 

were considered representative of the “test” location, and the samples from the river side were 

considered the “control” location (5 test and 5 control samples per night). All samples were filtered 

through a 505 micron net suspended in a barrel sampler, preserved in 10% buffered formalin, and 

processed in the laboratory to indentify and enumerate the ichthyoplankton species collected in four 

life stage categories: eggs, yolk sac larvae, post yolk sac larvae, and juveniles. Length (mm total 

length) was measured for a random subsample of up to 25 larvae and juveniles of each 

ichthyoplankton taxon in each test or control sample. In addition to the nighttime sampling, three 

pairs of daytime samples were collected one day each week from June through August. The final 

achieved sampling designs for each year, 2004 through 2007, were as follows: 

Year

Sampling Dates Number of Samples 

Start End Day Night Total 

2004 10-May 15-Oct 24 358 382 

2005 28-Apr 13-Oct 24 392 416 

2006 22-May 13-Oct 18 324 342 

2007 27-May 15-Oct 18 320 338 

2004-07 28-Apr 15-Oct 84 1,394 1,478 

Post yolk sac larvae was the dominant life stage in all samples, contributing 91% (2,380) of the total 

ichthyoplankton collected at the test location (2,619) and 94% (17,661) of the total ichthyoplankton 

collected at the control location (18,730) over the four-year study. 

The Lovett AFB evaluation focused on six target taxa: striped bass, white perch, river herring 

(alewife and blueback herring), bay anchovy, American shad, and Atlantic tomcod. However, only 

the first four taxa were caught in sufficient numbers to estimate the exclusion effectiveness. 

The AFB system installed and operated at Lovett during 2004 through 2007 exhibited an average 

exclusion effectiveness of 79% for all species and life stages of ichthyoplankton combined, with 

inter-annual variation ranging from a low of 40% in 2004 to a high of 95% in 2007 (Table 1). The 

Lovett AFB was estimated to exclude, on average among the four years, 89% of the bay anchovy 

(inter-annual range 68% to 100%), 89% of the striped bass (inter-annual range 85% to 94%), 85% of 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 38 Normandeau Associates, Inc.

the white perch (inter-annual range 62% to 97%), and 52% of the river herring (inter-annual range of 

-57% to 99%) over the four years of testing. 

The Lovett AFB system did not exhibit size selectivity in its exclusion efficiency during 2004 

through 2007. Kolmogorov-Smirnov two-sample tests (Siegel 1956; SAS 2003) of the standardized 

(percent) length-frequency distributions from the ichthyoplankton collected and measured from both 

the test and control locations were not significantly different (p>0.05) indicating no size selectivity of 

the AFB for all taxa combined (p>KSa = 0.9375), or for bay anchovy (p>KSa = 0.8079), striped bass 

(p>KSa = 0.8186), white perch (p>KSa = 0.8186), and river herring (p>KSa = 1.0000). Figure 1 

illustrates the absence of statistically significant size selectivity by comparing the length frequency of 

all taxa collected and measured in one millimeter length groups from the test and control locations 

during the 2004 through 2007 study. 

A likely explanation for the absence of significant size selectivity of the Lovett AFB is that the 

effective mesh opening of the non-woven outer layer (0.5 mm) was typically smaller than the smallest 

(i.e. “limiting”) dimensions of the fish eggs and larvae exposed to entrainment at the Lovett CWIS. 

The table below compares the length range and greatest body depth range for bay anchovy, striped 

bass, white perch and river herring larvae from measurements taken in Indian Point entrainment 

samples (1983-1987), and demonstrates that nearly all of the larvae of fish taxa exposed to the Lovett 

AFB were considerably larger than 0.5 mm in limiting body dimensions. 

Larval Fish Taxon 

Total Length Range 

(mm) 

Greatest Body Depth Range 

(mm) 

Bay anchovy 1.8-42 0.2-7.1 

Striped bass 3.2-56 0.5-10.6 

White perch 2.0-90 0.3-22 

River herring 3.3-59.7 0.2-13.2 

As a result, ichthyoplankton appearing inside the deployed Lovett AFB and sampled at the test 

location would likely have originated in unfiltered water from the control location outside of the AFB 

that had entered by either overtopping, underflow, or by other means indicating partial failure of the 

deployment. Unfiltered water sampled at the test location would be expected to have the same length 

frequency of ichthyoplankton as water sampled at the control location, because the water did not pass 

through the mesh openings where size selectivity would occur. Some ichthyoplankton sampled inside 

the deployed AFB at Lovett may also have originated from individuals trapped inside during 

deployment, depending on when deployment occurred relative to the onset of the spawning season 

(May) for most species of Hudson River fishes. When the AFB was deployed at Lovett in late April 

(2005) or early May (2004), which was prior to the spawning season, the first weekly samples from 

both inside and outside the filter barrier exhibited zero densities of ichthyoplankton (ASA 2004, 

2005). However, when the Lovett AFB was deployed during the spawning season in late May of 

2006 and 2007, the first weekly samples from both inside and outside of the filter barrier contained 

ichthyoplankton (ASA 2006, 2007). 

The 79% overall average percent effectiveness and the absence of size selectivity both suggest that 

performance of the Lovett AFB is directly related to its time of deployment with respect to the 

Hudson River fish spawning season, the proportion of the total intake flow drawn directly through the 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 39 Normandeau Associates, Inc.

filtration mesh, and the density of ichthyoplankton in the volume of unfiltered water drawn into the 

intake when deployment fails. 

4.3 REFERENCES

ASA Analysis and Communication, Inc. (ASA). 2003. Gunderboom MLESTM Evaluation Study at 

the Lovett Generating Station - Results of 2003 Biological Monitoring. Prepared for Mirant 

New York, Inc. 

ASA Analysis and Communication, Inc. (ASA). 2004. Gunderboom MLESTM Evaluation Study at 

the Lovett Generating Station - Results of 2004 Biological Monitoring. Prepared for Mirant 

Lovett, LLC. 

ASA Analysis and Communication, Inc. (ASA). 2005. Gunderboom MLESTM Evaluation Study at 

the Lovett Generating Station - Results of 2005 Biological Monitoring. Prepared for Mirant 

Lovett, LLC. 

ASA Analysis and Communication, Inc. (ASA). 2006. Gunderboom MLESTM Evaluation Study at 

the Lovett Generating Station - Results of 2006 Biological Monitoring. Prepared for Mirant 

Lovett, LLC. 

ASA Analysis and Communication, Inc. (ASA). 2007. Gunderboom MLESTM Evaluation Study at 

the Lovett Generating Station - Results of 2007 Biological Monitoring. Prepared for Mirant 

Lovett, LLC. 

EPA (U.S. Environmental Protection Agency). 2004. National Pollutant Discharge Elimination 

System—final regulations to establish requirements for cooling water intake structures at 

Phase II existing facilities. 40 CFR Parts 9, 122, 123, 124, and 125. Federal Register 

69(131): 41756-41693. 

Lawler, Matusky, and Skelly Engineers (LMS). 1996. Lovett Generating Station Gunderboom 

System Evaluation Program 1995. Prepared for Orange and Rockland Utilities, Inc. 

Lawler, Matusky, and Skelly Engineers (LMS). 1997. Lovett Generating Station Gunderboom 

System Evaluation Program 1996. Prepared for Orange and Rockland Utilities, Inc. 

Lawler, Matusky, and Skelly Engineers (LMS). 1998a. Lovett Generating Station Gunderboom 

System Evaluation Program 1997. Prepared for Orange and Rockland Utilities, Inc. 

Lawler, Matusky, and Skelly Engineers (LMS). 1998b. Lovett Generating Station Gunderboom 

System Evaluation Program 1998. Prepared for Orange and Rockland Utilities, Inc. 

Lawler, Matusky, and Skelly Engineers (LMS). 2005. Biological Monitoring Program Related to the 

Effectiveness Evaluation of the Lovett Generating Station Gunderboom Marine Life 

Exclusion System (MLES). Prepared for Mirant Lovett, LLC. 

SAS Institute, Inc. (SAS). 2003. The data analysis was generated using SAS software, Version 9 of 

the SAS System for Windows. Copyright © (2002-2003) SAS Institute Inc. SAS and all 

other SAS Institute Inc. product or service names are registered trademarks or trademarks of 

SAS Institute Inc., Cary, NC, USA. 

Siegel, S. 1956. Nonparametric statistics for the behavioral sciences. McGraw-Hill Book Company, 

Inc. 312 p. 

Sokal, R.R., and F.J. Rohlf. 1969. Biometry. The principals and practice of statistics in biological 

research. W.H. Freeman and Company. 776 p. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 40 Normandeau Associates, Inc.

Lovett Gunderboom Size Selective 

Exclusion Effectiveness for All Fish Species 2004-2007 

0%

5%

10%

15%

20%

25%

30%

35%

13579

1113151719

21232527

293133

Length Group (mmtl)

Test (n=439)

Control (n=2459)

Figure 4-1. Length Frequency (one mm length groups) of all larval fish taxa combined 

collected by simultaneous pairs of samples taken inside (test) or outside 

(control) of a deployed AFB at Lovett Station on the Hudson River, New York, 

from May through October 2004, 2005 and 2007 (2006 length data not 

available). 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 41 Normandeau Associates, Inc.

Table 4-1. Summary of annual percent exclusion effectiveness for fish larvae 

collected by simultaneous pairs of samples taken inside and outside of a 

deployed AFB at Lovett Station on the Hudson River, New York, from May 

through October 2004, 2005, 2006 and 2007. 

Fish Taxon Year 

Percent of 

Catch 

Percent 

Effectiveness 

Bay Anchovy 2004 34% 68% 

 2005 32% 99% 

 2006 39% 89% 

 2007 52% 100% 

2004-07 Mean 39% 89% 

Striped Bass 2004 35% 85% 

 2005 43% 94% 

 2006 21% 90% 

 2007 22% 88% 

2004-07 Mean 30% 89% 

White Perch 2004 2% 62% 

 2005 3% 97% 

 2006 8% 89% 

 2007 1% 92% 

2004-07 Mean 4% 85% 

River Herring 2004 1% -57% 

 2005 1% 84% 

 2006 4% 81% 

 2007 2% 99% 

2004-07 Mean 2% 52% 

All Species 2004 100% 40% 

 2005 100% 92% 

 2006 100% 89% 

 2007 100% 95% 

2004-07 Mean 100% 79% 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 42 Normandeau Associates, Inc.

5.0 VERIFICATION OF COMPUTER CODE

5.1 APPROACH

Three separate SAS programs were subjected to independent QC and verification to validate the 

estimates of entrainment and impingement reductions for various technology alternatives evaluated 

for IPEC. The three programs were developed and run by Dr. John Young of ASA Communications, 

Inc. and subjected to QC inspection and verification by Ms. Susan Ward (SAS Programmer) and Mr. 

Paul Lindsay (Fisheries Scientist) of Normandeau. The SAS programs subjected to QC and 

verification were as follows: 

1. Program 1h (22 September 2009 Revision), consisting of 6,865 individual programming steps 

(lines of code) used to estimate current entrainment rates and their age 1 equivalents for IPEC 

based on an association developed between past rates (1983-87) and past in-river densities 

compared to present rates and present in-river density data for fish eggs and larvae derived 

from the Hudson river monitoring program data. The number of lines actually reviewed was 

far in excess of 6,865, because line numbers shown in the SAS code are only assigned to 

original program code and not to the many lines of notes inserted between them by SAS 

when the program is executed, showing the numbers of observations and variables in the 

intermediate data sets that were an important part of the material inspected during the 

verification process. 

2. Program IP-CollEff1981-1990 (22 September 2009 Revision), consisting of 187 individual 

programming steps (lines of code) used to estimate impingement collection efficiency 

coefficients for application to estimate impingement rates from 1981 through 1990 actual 

impingement data for IPEC. 

3. Program IP-StrataImpByLengthClass1981-1990 (22 September 2009 Revision), consisting of 

549 individual programming steps (lines of code) used to apply the collection efficiency 

coefficients developed by Program IP-CollEff1981-1990 to calculate collection efficiency 

adjusted impingement counts for Unit 2 and Unit 3 of IPEC by year, stratum, and taxon from 

1981 through 1990 for IPEC. 

The QC and verification was based on independent checks of the written code, input files, and output 

generated for each SAS program. Each program was rerun by Normandeau in a single pass (rather 

than one part at a time) and the results were compared to the preliminary analysis, to verify that the 

same input data were used for the quality control as for the preliminary runs of program steps. The 

SAS logs (output from SAS documenting the progress of the data input, processing, and output steps) 

were examined in detail to ascertain the data pathways between the input and output data files. The 

number of observations reported by these SAS logs in the intervening steps (“work files”) were 

reviewed to determine how the data files were manipulated with respect to the dimensions of the 

sampling design (“sort variables”). The internal documentation (“comments”) and the program code 

were compared to make sure that they were in agreement and that the calculations are technically 

sound and performing as intended. 

Several sections of the program were tested by independently (i.e. by hand) calculating values from 

input variables to verify that the results matched the output files produced by the program, to make 

sure the program was performing as expected. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 43 Normandeau Associates, Inc.

No attempt was made to verify the equations or parameters for impingement survival, mechanical 

entrainment survival, thermal entrainment survival, or plant operating data (those are from earlier 

work that has been reviewed and accepted)—these equations and parameters were merely verified as 

producing values (e.g., survival rates) within reasonable ranges. 

Notes were made in a bound copy of the SAS log. The results of the QC and verification process 

were summarized in Section 5.0 of Normandeau’s Appendix B report dated January 2010. 

Calculations made during the QC and verification and additional comments were also documented in 

Excel files of some of the intermediate data sets (or subsets of them). 

Red font in the documentation below indicates potential issues identified by Normandeau for 

resolution. Follow-up response by ASA is noted in blue font. 

5.2 PROGRAM 1H.SAS (22SEP09 REVISION) 

5.2.1 Entrainment Section 1—Estimate River Standing Crops for 1983-1987 and 

2000-2007 

Lines: 13,916-13,990 

Input: work.LRSlv345 (72,142 obs.) 

Output: work.mean8 (1,687 obs.) 

Purpose: Calculate mean density (by taxon year week region strata) and weight by strata 

volumes to get “standing crop” (by taxon year week), representing a weighted mean 

density. 

Comments: For the 7 taxa, 241 combinations of year/week, and 8 combinations of region/strata 

there should be 13,496 obs. There are 56 obs. missing because of 8 missing 

combinations of year/week/region/strata for each of the 7 taxa, causing the missing data 

as to be counted zero densities in calculating the means. 

Follow-up: The 8 missing cells are: 

Year Week Region Strata 

1984 19 4 1, 2, 3 

1984 22 4 2 

1984 22 5 2 

1985 21 4 1 

2001 11 5 2, 3 

Although substitution could be done from sampled strata, the infrequent occurrence of 

missing strata would have only a minor, if any, effect on the results. For instance, in 

week 11 all taxa except Atlantic tomcod would have had zero abundance, thus no bias 

would have occurred due to the two strata in region 5 going unsampled. No action 

taken. 
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Appendix B 2-1-10.DOC, 2/2/10 44 Normandeau Associates, Inc.

5.2.2 Entrainment Section 2—Estimate Entrainment Densities for 1983-1987 

Lines: 14,431-14,437 

Input: work.Lv3456 (186,592 obs.) 

Output: work.entcheck (16,044 obs.) 

Purpose: Calculate daily mean entrainment densities and total volumes sampled to verify against 

annual report tables. 

Comments: Compared values for striped bass between work.entcheck and report Table B-2 of the 

1987 entrainment abundance report. For some dates the daily volumes are too high and 

densities are too low because void samples were included in the calculation, causing 

the void samples to be treated as zero densities in calculating the means. Void samples 

should be deleted from the analysis. Other daily means differed slightly (by <5%, 

usually <1%). Those small differences can be attributed to the weighting effect of 

calculating the means slightly differently than in the report (due to small differences 

among sample volumes and whether replicate samples were pooled before averaging 

the 2-hour periods together). Both averaging methods are defensible and the close 

similarity of their results justifies the current approach. 

Follow-up: For 1985-1987 data, level 3 data were selected to use only USE_CODE = 1 samples. 

For 1983 and 1984 data, level 5 records were dropped if sample volume was missing or 

0. When level 34 (merged level 3 and 4 if record exists in level 3) and level 5 were 

merged, records were retained only if sample exists in both lv34 and lv5. 

Lines: 14,468-14,516 

Input: work Lv3456 (186,592 obs.) 

Output: out.E02_entweeklyden (651 obs.) 

Purpose: Calculate weekly mean entrainment densities. 

Comments: Compared values for striped bass in week 24 of 1987 (Sunday 14Jun through Saturday 

20Jun) between out.E02_entweeklyden and Table B-2 of the 1987 entrainment 

abundance report. Values are in agreement (except for very small rounding errors). 

Lines: 14,616 

Input: out.entweeklyden (837 obs.) 

Output: printout of that file 

Comments: This is an old file name from a prior version of the program (the updated 

out.E02_entweeklyden has 651 obs.). The subsequent analysis is not affected because 

it doesn’t use out.entweeklyden (this print step can be ignored). 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 45 Normandeau Associates, Inc.

5.2.3 Entrainment Section 3—Relationship of Entrainment Density to Standing Crop 

Lines: 14,750-15,199 

Input: out.E02_entweeklyden (651 obs.) 

out.E01_LRSweeklycrop (1,687 obs.) 

Output: out.E03_entriverout (364 obs.) 

out.E03_predparms (28 obs.) 

Purpose: Use geometric mean regression to relate river standing crop in regions 3-5 with 

entrainment densities by taxon stage week during 1983-1987 when the two programs 

coincided; substitute the ratio of the means from the two programs when regression 

was unsuccessful. 

Comments: The program code is consistent with the stated method (did not attempt to 

independently run the regressions) 

5.2.4 Entrainment Section 4—Predict 2000-2007 Entrainment Densities 

Lines: 15,327-15,476 

Input: out.E01_LRSweeklycrop (1,687 obs.) and out.E03_predparms (28 obs.) 

Output: out.E04_ent_00_07 (5,549 obs.) 

Purpose: Estimate weekly standing crops for 2000-2007 by linear interpolation for unsampled 

weeks between the first and last weekly occurrence by taxon stage year and combine 

the resulting data sets with the parameters developed in entrainment step 3 to estimate 

entrainment densities for 2000-2007. 

Comments: Independently calculated weekly striped bass entrainment densities for all four life 

stages using data from the input files, and then compared the values with those in the 

output file. The values agreed exactly. 

5.2.5 Entrainment Section 5—Estimate 2000-2007 Entrainment Length-Frequencies 

Lines: 15,507-15,536 

Input: out.E02_entlenfreq (3,426 obs.) 

Output: work.weeklyLF (1,435 obs.) 

Purpose: Calculate proportion in each length class by taxon stage week for all years of 

entrainment measurement data combined. 

Comments: Independently calculated weekly length class proportions for striped bass PYSL using 

the input data and compared them to several values in the output file 

out.E05_entdenlen. The values agreed exactly. 

Lines: 15,538-15,647 

Input: work.weeklyLF (1435 obs.) 

Output: work.weeklyLFlags (27,153 obs.) 

Purpose: Use length class proportions from the first and last weeks of the entrainment data set 

(weeks 18 and 29) to estimate proportions in weeks before and after those weeks. 

Comments: Examined several values for striped bass in the output file out.E05_entdenlen for weeks 

<18 and >29. They all contained the appropriate values. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 46 Normandeau Associates, Inc.

5.2.6 Entrainment Section 6—Create Flow Data Sets 

Lines: 15,740-15,902 

Input: old.ipopdata (3,288 obs.) 

Output: out.E06_flow (9,864 obs.) 

Purpose: Plant flows for scaling up entrainment densities to numbers entrained. 

Comments: Examined a subset of the output file (2003 values only). U1SWflow is always zero for 

case 0 (baseline). For 26Oct 03, U2CWflow exceeds the capacity flow for all 6 pumps 

running for 24 hours. 

Follow-up: U1SWflow reset to 16,000 gpm for baseline case. Data for 26Oct03 are somewhat 

high for all unit 1 and 2 flows and for MW variables for both units. However, values 

are not high enough to distort the analysis. 

5.2.7 Entrainment Section 7—Survival and Exclusion Parameter Values 

Lines: 15,927-16,259 

Input: excldata.csv (345 obs. from Normandeau’s mesh exclusion analysis) 

other parameters input as “cards” or by program code 

Output: out.E07_casedefs (23 obs.) 

out.E07_entsurv (476 obs.) 

out.E07_excludesurv (576 obs.) 

out.E07_excldata (2,940 obs.) 

Purpose: Provide definitions of the various cases and parameter values for estimating 

entrainment survival, physical exclusion based on slot width/mesh size, and 

impingement survival of excluded organisms. 

Comments: Case 0.5 (full flow with entrainment survival) is one of the cases with the parameters 

for 100% mortality, however these wrong parameters do not get used to calculate 

entrainment survival for case 0.5 in section 8 below. 

5.2.8 Entrainment Section 8—Calculate Numbers and Losses by Case 

Lines: 16,316-16,371 

Input: R01.ichwclv5 (5,206 obs.) 

R02.ichwclv5 (5,498 obs.) 

R03.ichwclv5 (5,509 obs.) 

R04.ichwclv5 (5,521 obs.) 

R05.ichwclv5 (5,522 obs.) 

R06.ichwclv5 (5,513 obs.) 

R07.ichwclv5 (5,506 obs.) 

R87.ichwclv5 (3,477 obs.) 

Output: work.wqmean (300 obs.) 

out.E08_entdenlenflow_lba (1,802,234 obs.) 

Purpose: Use weekly mean salinities from regions 3-5 to calculate mechanical entrainment 

survival by case taxon lif_stag length year week date. 

Comments: Examined a subset of out.E08_entdenlenflow_lba (May-August 2003 striped bass 

PYSL data for cases 0, 0.5, 1, 4, 10, 10.5, 14, and 15). Salint=1 in all 8,792 obs. 

examined. One is the default value for weeks that have no salinity data, so that value 

should occur rarely if at all. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 47 Normandeau Associates, Inc.

Follow-up: Salint was added to the keep statements when the work.Baseline, work.Alternative, 

and work.ClosedCycle data sets are created. 

Lines: 16,613, 16,614 

Purpose: Assign avoidance factor for the AFB alternative based on the percentage of Lovett’s 

intake flow that was not filtered by the Gunderboom. 

Comments: Avoidance factor (favoid) for AFB should be 0.79 rather than 0.82 (which was a 

preliminary value that has been subsequently revised).

Follow-up: favoid changed to 0.79. 

Lines: 16,310-16,778 

Input: out.E06_flow (9,864 obs.) 

out.E05_entlenden (18,653 obs.) 

out.E07_excldata (2,940 obs.) 

out.E07_entsurv (476 obs.) 

out.E07_excludesurv (576 obs.) 

Output: out.E08_entdenlenflow_lba (1,802,234 obs.) 

Purpose: Merge flows, discharge temperatures, predicted entrainment densities, exclusion 

factors, entrainment survival parameters, and impingement survival parameters and 

calculate the numbers avoiding, excluded, and entrained by each case taxon stage 

length year week date, and the corresponding losses (for each unit, separately for CW 

flow and SW flow). 

Comments: Sm (daily mechanical entrainment survival rates): verified for cases 1, 4, 10, 10.5, and 

14 using length, salinity, and the entrainment survival parameters ME0, MEL, LamE, 

alpha, and gamma for striped bass PYSL in May-August 2003 and checked to see that 

it is zero for cases 1 and 15 and that it is the same for case 0.5 as for case 1 (all OK). 

Wrong mechanical survival parameters for case 0.5 (100% mortality) are OK because 

they do not get used in the calculations. ST2 (daily Unit 2 thermal entrainment 

survival rates): verified the for cases 1, 4, 10, 10.5, and 14 using distemp2, beta, and 

Tcrit for striped bass PYSL in May-August 2003; checked to see that ST2 is the same 

for case 0.5 as for case 1; and looked at plots of ST2 against distemp2 to make sure the 

parameters represent plausible curves (all OK). Non-zero thermal survival rates for 

case 0 (baseline, where all values are 99% or 100% survival) and for case 15 (closed 

cycle, where the values are above but close to zero) are OK because they all get 

cancelled out by a mechanical survival rate of zero. Sx (daily impingement survival 

rates of “entrainables” that are excluded by technology alternatives): verified for cases 

4, 10, and 10.5 using length and the impingement survival parameters Aimp, Bimp, and 

Cimp for the striped bass PYSL in May-August 2003 and looked at plots of Sx against 

length to make sure the parameters represent plausible curves (all OK). Values for 

cases 0, 0.5, 1, 14, and 15 are irrelevant in these examples because exclusion is always 

zero. SWEnt1 is always zero for cases 0 and 0.5 because U1SWflow is always zero 

for those two cases. Ent3 (daily estimated number entrained by the Unit 3 cooling 

water flow): verified for cases 0, 0.5, 1, 4, 10, 10.5, 14, and 15 using pent, entfreq, 

U3CWflow, exclusion, and (for case 4) length for striped bass PYSL in May-August 

2003 (all OK). TotLoss_mil (daily entrainment losses): verified for cases 0, 0.5, 1, 4, 

10, 10.5, 14, and 15 using SWEnt1, SWEnt2, SWEnt3, Ent2, Ent3, Sm, ST2, ST3, 

SWExc2, SWExc3, Exc2, Exc3, Sx, and (for case 10.5) Slatent for striped bass PYSL 

in May-August 2003. Entrainment losses were correctly calculated from those 

variables, but the losses from the Unit 1 service water are missing. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 48 Normandeau Associates, Inc.

Follow-up: Baseline U1SWflow changed to 16,000 gpm. 

5.2.9 Entrainment Section 9—Calculate Equivalent Life Stage Values 

Lines: 16,898-17,761 

Input: stageequiv (9 obs., cards) 

balparm (9 values in the code) 

spottailLH (28 obs., cards) 

fecundity (46 obs., cards) 

Life Tables061109.csv (228 obs.) 

Output: out.E09_eqloss_A1_balanced (256 obs.) 

Purpose: Calculate factors for converting losses into biomass production (“production forgone”), 

yield, and consumption. 

Comments: Independently calculated several of the intermediate variables for survival, mortality, 

growth, and weight, both cumulative and within life stage, for most of the taxa/life 

stages from the input values. Verified the life cycle balancing by independently 

calculating the lifetime fecundity per egg (OK). Verified the calculation of eqage

(used for calculating age 1 equivalents): OK. Independently calculated values for 

Cum_Pi (cumulative biomass production in grams forgone per individual entrained at 

each life stage over the entire lifespan) for five life stages of alewife and striped bass: 

egg values matched exactly but other stages disagreed, often by a fraction of 1% but 

sometimes by as much as 10-14% because the production forgone for the entrained 

stage uses weight (the start weight of the stage) instead of medweight (the weight at 

entrainment, at the median death of the entrained stage). The sum of duration over the 

first year of life for all taxa except spottail shiner is longer than 365 days, making 

age>365 days for the start of stage A1, the age of equivalence. This doesn’t affect the 

analysis though, which is based on the correct stage mortality rates (Zdur was 

calculated after multiplying daily mortalities F and M by duration, but those daily 

mortalities were originally calculated by dividing stage mortalities by the inflated 

durations, so the effect of the excess days in age 0+ is cancelled out). One effect of the 

extra age 0+ days is that spottail shiner stage A1_06 (the first month after the age of 

equivalence) is put into work.stageage in the early part of step 10 but we ultimately 

don’t present spottail shiner entrainment data. Values of either Yi or Ci (or both) are 

questionable because when compared with independent estimates of total future 

biomass production (which would include biomass that goes to both fisheries and 

consumption), the sum of Yi+Ci ranged from 23% to 313% higher than the combined 

sum of the weight at the time of entrainment (medweight) and all future biomass 

production (cum_Pi) per entrained individual in 10 examples examined. The lost 

consumption values, which are calculated from Ci, are not ultimately used in the 

alternatives report. As far as Yi is concerned, we could just assume that Baranov’s 

Catch Equation for the equivalent yield model (EPRI 2004) is defensible. 

Follow-up: medweight substituted for weight in equation for Pi_loss. Yi is an approximation to 

the true age-specific lost yield. Depending upon survival and fishing mortality values, 

Yi may over or underestimate the true lost yield. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 49 Normandeau Associates, Inc.

5.2.10 Entrainment Section 10—Convert Entrainment Loss to Equivalent Loss 

Lines: 17,775-17,787 

Input: out.E09_eqloss_A1_balanced (256 obs.) 

Output: work.LHeqloss (223 obs.) 

work.stageage (96 obs.) 

Purpose: Assign lif_stag=0 to eggs, lif_stag=1 to YSL, lif_stag=3 to PYSL, and lif_stag=5 to 

every other stage. 

Comments: eggs for taxa 3, 32, and 35 and PYSL of taxon 28 are assigned the wrong lif_stag (5, 

which is juveniles) because of mismatches in stg_name. For example, stg_name=eggs 

for some taxa but stg_name=egg for other taxa (without the final “s”). This does no 

harm in work.stageage because that file is only used to provide stg_num for the 

lif_stag=5 (juvenile) entrainment estimates. Spottail shiner yearlings in June are 

assigned the wrong lif_stag (5, juveniles) because line 17,785 includes stg_num=15 

for spottail shiner due to its age (365 days). This also does no harm in work.stageage, 

for the same reason (and also because we ultimately don’t present entrainment losses 

for spottail shiner). The same wrong lif_stag values are merged from work.LHeqloss 

into the full entrainment data set work.ent, but his does no harm either, because the 

merging is done by stg_num rather than by lif_stag and no further data manipulations 

are done by lif_stag. 

Lines: 17,812-17,818 

Input: work.ent2 (430,192 obs.) 

work.stageage (96 obs.) 

Output: work.ent2 (430,260 obs.) 

Purpose: Merge entrainment loss data for juveniles with life history data by taxon lif_stag 

month. 

Comments: 60,191 obs. from work.ent2 did not match up with any records in work.stageage 

(mostly cases of juveniles being entrained in the month before the month in which the 

juvenile stage is reached according to out.E09_eqloss_A1_balanced, except for 

American shad entrained in July, which didn’t match because there is no record in 

out.E09_eqloss_A1_balanced for shad in July). This is rectified by assigning 

stg_num=4 to these records. 68 obs. from work.stageage did not match up with any 

records in work.ent2, resulting in work.ent2 after the merge having 68 extra obs. with 

missing values for totent_mil, totLoss_mil, and other variables originally from 

out.E08_entdenlenflow_lba. Stg_num=4 is assigned to these 68 unmatched records, 

replacing the correct stage_num, but these records do not affect the subsequent totals 

because of the missing loss values. 

Line: 17,832-17,837 

Input: work.LHeqloss (223 obs.) 

work.ent (1,802,302 obs.) 

Output: work.ent (1,802,302 obs.) 

Purpose: Merge life history parameters with entrainment loss data by taxon stg_num. 

Comments: At least one record has the wrong month value. Shad eggs occurred only in 2002, and 

only in two weeks of that year (each represented by seven daily estimates in the file), 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 50 Normandeau Associates, Inc.

resulting in 322 records (23 cases, 1 year, 2 weeks, 7 days per week). In the first day of 

the first week, case 0 differs from all 22 other cases in the value of month (5 for case 0 

and 4 for all other cases on that date). This resulted from merging two files with 

different values for the variable month but the same values of taxon and stg_num. 

For the analysis we want the month value from work.ent, so perhaps month should be 

dropped from work.LHeqloss before the merge. A month discrepancy also occurred in 

other records in the merged file, including records from 1987 (which does no harm 

because it is not used for subsequent analysis) and some records with stg_num=4 and 

missing values for the entrainment numbers and losses (which shouldn’t affect the 

outcome because the estimates will be summed later by month). 

Follow-up: Code changed so that month variable not brought into work.ent1. Note it is needed in 

work.ent2. 

Line: 17,845 

Input: totloss_mil, cum_Pi, S1

Output: prodforgn_kg

Purpose: Multiply the production forgone per entrained individual (in grams) by the number of 

entrained organisms lost (in millions) to estimate the biomass production forgone (and 

convert to kilograms). 

Comments: Dividing by S1 is not necessary because cum_Pi already has accounted for entrainment 

occurring at the median death of the entrained stage, and therefore dividing by S1 now 

inflates the production forgone estimates (not only of the entrained stage, but also 

every subsequent stage up to the expected lifespan). 

Follow-up: Code changed to remove S1 from the calculation. 

5.2.11 Entrainment Section 11—Produce Output Tables 

Lines: 17,953-17,970 

Input: out.E10_losssummary2_lba (1,111 obs.) 

Output: work.SBratio (8 obs.) 

Purpose: Estimate proportion of striped bass production forgone that would have resulted in 

fishing yield, for converting production forgone of other species into striped bass 

equivalent lost yield. 

Comments: Overestimation of production forgone due to dividing cum_Pi by S1 in line 17,845 

would cause the ratio to be too low (but if lost yield is too high, that could have a larger 

influence, causing the ratio to be too high). 

Follow-up: Change to previous section will correct. 

Lines: 18,011-18,046 

Input: out.E10_losssummary.lba (6,246 obs.) 

Output: work.monthlyalternatives (5,658 obs.) 

work.negred (1 obs.) 

Purpose: Calculate monthly percent reductions from baseline for numbers entrained, entrainment 

losses, and entrainment age 1 equivalent losses by case taxon year (work.negred is for 

any negative percent reductions). 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 51 Normandeau Associates, Inc.

Comments: Shad in April 2002 has a negative percent reduction for all three metrics due to the 

month error for the baseline case in section 10. 

Follow-up: This issue corrected by dropping month from Ent1 data set. 

5.2.12 Impingement Sections 1 and 2—River Abundance in 1983-1987 and 2000-2007; 

Correlation of Standing Crops 

Lines: Beginning 18547 and 18901 

Input: Beach Seine and Fall Shoals program datasets for 1983 – 1990 and 2000 – 2007. 

Purpose: Determine standing crop for both programs, and to correlate various life stages across 

the two programs. 

Comments: Confirmed selection of data, verified correlation coefficients and level of significance 

of correlations. In the merge of LV34 and LV5 the result contains 3 records more than 

expected (66968 – LV34, 68940 (LV5), resulting file is 66971. 

Follow-up: Corrected by summing LV5 by year, taxon and sample to eliminate multiple LV5 

records for same sample. 

Lines: 18,800-18,849 

Input: work.fsslv345 (66,971 obs.) 

old.volarea (39 obs.) 

Output: work.mean4 (9,328 obs.) 

work.mean5 (1,248 obs.) 

Purpose: Average FSS densities by taxon year week region strata, convert to standing crop 

estimates using stratum volumes, combine regions and strata (for regions 3-5) by taxon 

year week. 

Comments: There are three issues with the FSS standing crops. One is a shoal sample in region 5 

in 2007 (a region not sampled in the shoal stratum). Another issue is that sampling in 

two weeks (week 29 in 1986 and week 29 in 2005) spilled over into the following 

week, causing two extra weeks in work.mean4 and work.mean5. This could be due to 

the dates, for example if sampling didn’t finish until Sunday. It could be rectified by 

changing all records for week 30 in 1985 and in 2005 to week 29. The third issue is 

that there are no stratum 3 samples in these 3 regions at all in the last 3 sampling weeks 

of the season in all years 2000-2007 (a design change that compromises the 

comparability of the standing crops from the 1980s and the 2000s). All these missing 

and extra strata have the effect of biasing the densities and standing crops low because 

of the mismatches in sampling design. The missing stratum 3 samples could be 

rectified by using an appropriate stratum volume weighting procedure that does not 

lower the mean density when a stratum is missing by effectively counting it as zero. 

Follow-up: Shoal samples in region 5 dropped. Week 30 reassigned as week 29. Deleted strata 3 

samples after week 42 in all years. 

5.2.13 Impingement Section 3—Merge Abundance Ratios with Densities and Estimate 

Impingement 

Lines: Beginning 19100 

Input: Impstratadensities, abundratios, flow (flow and op data, 2000-2008) 

Output: Impdenflow, StrataMeans 

Purpose: Estimate impingement. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 52 Normandeau Associates, Inc.

Comments: Merges impdensities and abundratios by taxon; Adjusts densities based on the ratios. 

Calculates flow for each Unit. Note that SW Unit 3 is assigned as 36,000 in 

entrainment section of program code, while the 1990 report indicated SW at Unit 3 is 

30,000. Sums flow over Case, Unit, Year, Strata, Month. Subsets Impdensity file for 

years >1983 (1984-1990 only used). Calculates mean daily adjusted number impinged 

by Unit Strata and Taxon (average over 7 years). Merges this file in to the Monthflow 

file that has been zerofilled for all 8 taxa. Assigns avoidance factors according to case, 

and ristroph survival coefficient according to taxon. Avoidance factor for case 14 

should be changed from 0.82 to 0.79. Calculates the “multiplier” – the avoidance 

factor adjusted number impinged. Calculates the number lost multiplier as the 

probability of “not” avoiding times the probability of not surviving impingement. 

Follow-up: New SW pumps for Unit 3 have higher capacity. Changed favoid to 0.79. 

5.2.14 Impingement Section 4—Convert to Equivalent Losses 

Comments: Confirmed assignment of year class, eliminating early life stages. Reviewed equivalent 

loss, lossyield_kg, lostconsum_kg, and prodforgn_kg. The equation for prodforgn_kg

should be modified by removing the S1 in the denominator. Remaining program steps 

were reviewed for appropriate subsetting. No issues were found. 

Follow-up: Removed S1 from denominator. 

5.2.15 Outstanding Consideration 

Comments: Confirm the correlation between the impingement densities calculated in this effort and 

the densities that are being prepared for delivery to NRC as part of an independent task. 

These efforts utilize similar source data and should be reviewed to confirm their 

confluence. 

Follow-up: Outputs for this effort and for the NRC delivery are substantially different and would 

be very difficult to compare. 

5.3 PROGRAM IP-COLLEFF1981 - 1990.SAS (22SEP09 REVISION) 

5.3.1 Step 1—Calculate Collection Efficiency Coefficients 

Lines: Beginning 766 

Input: IMPWCLV5 for the period 1981-1990 

IMPDFLV3 for the period 1981-1990 

Output: ALL_CE8190 (N=5888) 

Purpose: Calculate collection efficiency coefficients by date for use in determining collection 

efficiency adjusted impingement counts. 

Comments: Water temperature is averaged across all three units, using task_cd=90 or task_cd=99 

records. 

 LV3 and LV5 records are merged, and the average water temperature by date is 

calculated. For instances where water temperature is missing, temperature is linearly 

interpreted from the preceding and succeeding dates. 

 Collection efficiency coefficients are calculated for each year, unit, and date based on 

the following equations: 

 Unit 2 Coll_Eff= (-0.00871 * H2O_Temp) + 0.51858; 

 Unit 3 Coll_Eff=(-0.00792 * H2O_Temp) +0.71640; 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 53 Normandeau Associates, Inc.

 Equations were confirmed against the 1990 report. 

Time interval over which temperatures were interpolated varied from a day to over 100 

days. 

Follow-up: Substantial periods sometimes passed between samples due to unit outages. No action 

taken. 

Lines: Beginning 968 – Joining sample collection data from LV3, LV4 for all years. 

Input: 1981 -1990 LV3, LV4 or LV4b data files. 

Output: All_LV3 (N=4616), 

ALL_LV4 (N=4613) merged to JOIN_SAMP (N=4616) 

Purpose: Gather field sample specific information containing unit, date, volume. 

Comments: LV3 and LV4 files are merged and resulting JOIN_SAMP file created (N=4616). 

Merges All_CE8190 and JOIN_SAMP to create SAMP_CE (N=4616) 

5.4 PROGRAM IP-STRATAIMPBYLENGTHCLASS1981 - 1990.SAS (22SEP09 REVISION) 

5.4.1 Step 2—Join Catch Data to the Collection Efficiency Data from Step 1 

Lines: Beginning 1044 

Input: 1981-1990 Level 5 files (IMPDFLV5 N=34789) 

SAMP_CE (N=4616) 

PAD_SAMP (zero filled file) (N=577000, which is 4616 samples x 125 taxa) 

Output: ADJ_CT (N=577007) 

SUM_CT (395000) 

Purpose: To calculate collection efficiency adjusted counts by year, unit, strata and taxon 

Comments: Creates a file with a records for every taxon for every sample (referred to as zero filling 

– in samples where a taxon was not collected, counts will be ‘0’, hence the file is zerofilled, allowing for the correct calculation of mean density). Merges this zero filled file 

with the LV5 file, expecting resulting file to be 577000 records. Sums adjusted counts 

by Year, Date, Unit and Taxon. 

Resulting file was 577007 records. Seven samples have two records for various taxa, 

and in 5 of the 7 cases, the counts on the records are different. 

Follow-up: If records have the same total_ct, it was assumed that a single valid record was 

duplicated. If the records have different total_ct, it was assumed both records were 

valid and they were combined into a single record. Resulting file has 577000 records. 

Of the taxa being used in this analysis, only a single sample date (1/11/1981) was 

substantially affected. On that date, for Unit 3, catch of yearling striped bass was 30 in 

one record and 21 in the other. For white perch, 21 yearling white perch were listed on 

one record, and 2307 on the other. Other instances for the 14 records were for taxa not 

used in this analysis. 

5.4.2 Step 3—Calculate Strata Numbers 

Lines: Beginning 1152 

Input: ADJ_CT (N=577007) 

Output: Strata_CT, Y81jj (1981 treated separately due to daily sampling, Strata_MN 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 54 Normandeau Associates, Inc.

Purpose: Adjust counts according to collection efficiency coefficients. Sum over samples to 

obtain year date unit and taxon sums. Extract Month from date, assign strata based on 

month and separate blue crabs from other taxa. Calculate a mean and standard error by 

year unit strata taxon. Determine the number of samples collected in each strata. 

5.4.3 Step 4—Bring in Plant Operation Data 

Lines: Beginning 1250 

Input: Circflow file: plant operation data; SUM_CT file 

Output: Countvol and StrataDens files 

 Final file is Impstratadensities 

Purpose: Obtain plant volume by date and adjust densities according to daily volume by year, 

date, and unit. 

Comments: Density = (collection efficiency adjusted daily count * 1000000) / daily volume. 

Computes average by year unit strata and taxon. 

5.5 VERIFICATION OF SENSITIVITY ANALYSIS AND CUMULATIVE ANALYSIS

After the alternatives analysis software program had been finalized following the QC and verification 

process described above, the program was further modified to accomplish two additional goals. One 

was to explore the sensitivity of the alternatives analysis outcome to variations in the parameters of 

the equation estimating larval fish avoidance to wedgewire screens as a function of larval length. The 

second goal was to relate the cumulative loss reductions of alternative technologies to the cumulative 

loss reductions of closed cycle cooling over the entire projected lifetime of IPEC operation to reflect 

differing implementation schedules. Normandeau was asked to perform a QC verification of the 

software developed for the sensitivity analysis and the cumulative analysis. ASA provided the 

revised software, IPEC Alternatives – Program 1H5_011110.sas, which included a new section “J01 

– Cumulative Analysis over Remaining Plant Life” at the end. 

The method of checking the new section of the program was the same as had been employed earlier 

for verifying the earlier sections. ASA’s finalized program code was set aside and a copy created for 

the purpose of modifying code to run in Normandeau’s network environment. Data libraries were 

resolved, input data files were reconciled, and the program was run iteratively, resolving all 

discrepancies until the program ran error free. A PDF document containing all of the output listings 

produced by the program, as well as a separate PDF document containing the SAS log file of code 

execution, were created. This allowed for careful review of program execution by facilitating 

inspection of intermediate steps in the execution process. Some program steps created intermediate 

data files that were saved automatically as Excel CSV files. Other program steps created 

“permanent” SAS datasets, which are not erased at the end of program execution. Selected SAS 

permanent datasets were also examined during the QC process. 

The sensitivity analysis was not reflected in the final program code, but rather had been performed by 

ASA rerunning the program varying the parameters in the single program line containing the 

avoidance factor equation. Normandeau confirmed the results of the sensitivity analysis by 

modifying the final SAS program, IPEC Alternatives – Program 1H5_011110.sas, to alter the lengthbased avoidance factor. The original model used the following equation: 

Avoidance factor = 1 – e(-0.275*(Length-4)) 

To test the results of the sensitivity analysis, the equation was modified to reflect one of the alternate 

formulations of the avoidance relationship that had been used in the sensitivity analysis: 

Avoidance factor = 1 –e(-0.18*(Length-8))
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 55 Normandeau Associates, Inc.

Results of the modified program confirmed the results of the sensitivity analysis. 

In addition to the program itself, ASA provided a series of SAS output datasets containing the results 

of the alternatives analysis. Part of the verification process was to compare these datasets to results 

independently generated by Normandeau using the SAS code provided by ASA. The Proc Compare 

routine in SAS compares SAS datasets based on all variables, and all records in each of two files. 

Records containing different variables or different values for variables, or datasets containing a 

different number of records are flagged. The results of Proc Compare for the seven output datasets 

provided by ASA showed initially that the first four datasets did not differ in any variable values from 

the Normandeau results, but that substantial differences were found in the final three summary 

datasets. Examination of the code and the discrepant results revealed that the output datasets 

provided by ASA reflected a different scenario run – comparing the losses under the alternative 

technology cases to the losses under the current technology case, rather than to the regulatory baseline 

case. Normandeau modified the code to calculate the loss reductions from the current technology, 

and performed the Proc Compare on all seven output datasets again. The results of the Proc Compare 

then indicated that all datasets obtained by ASA and Normandeau, Out2 through Out8, were 

equivalent. Discrepancies between corresponding variable values in the two datasets were nearly 

always less than 0.0001% (one part in one million). The few small discrepancies that were found 

were reasonable results of differing versions of SAS and differing hardware between ASA and 

Normandeau. This exercise verified that the results of the program could be independently replicated.

Other steps in the verification process for the cumulative analysis included following the data flow 

throughout the new section J01 to verify that the intermediate data sets contained the appropriate 

number of observations and independently recalculating the results of intermediate steps for several 

data points. The code was examined and examples were recalculated to verify that the program 

performed as described in the internal documentation (comment lines in the program). The steps in 

the cumulative analysis in the new program section J01 performed as designed and all values checked 

were correctly calculated by the program.
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 56 Normandeau Associates, Inc.

Attachment B-1

Literature Review of Fish Larvae Avoidance Swimming Behavior as Applied to IPEC

Clutter and Anraku (1968) reviewed several published studies and concluded that avoidance of towed 

plankton nets by larval fish is supported by overwhelming evidence. Factors influencing the degree 

of avoidance included larval detection of turbulence of water passing through the mesh, larval 

detection of a pressure front before contact with the sampling gear, the approach speed, and the size 

of the sampling gear. Although these observations were based on plankton nets moving through a 

(relatively) stationary water mass containing the larvae, the same principles should apply to stationary 

CWW screens in a moving water mass containing larvae. The extensive body of evidence 

demonstrating larval avoidance of plankton nets establishes the means by which fish larvae are 

capable of CWW screen avoidance: their swimming ability. 

The scientific literature has a large amount of information on the swimming capabilities of fish and 

fish larvae from as early as 1926 (Breder 1926, cited in EPRI 2000). The most recent tabulation of 

fish swimming capabilities from the peer reviewed scientific literature was published by Beamish 

(1978), and reviewed by Hammer (1995). There are several types of swimming behavior exhibited 

by fish (EPRI 2000): 

 cruising is the normal swimming activity sustained by fish performing their daily activities, 

 critical swimming is the prolonged swimming speed a fish can maintain when forced to swim 

in a confined space of continuous flow, 

 burst swimming is avoidance activity represented by short-duration darts, and 

 fast start swimming is the initial thrust of a burst swimming activity. 

The various authors presented in this review have used different terms to differentiate among these 

swimming behaviors. In this review, we will use the authors’ original terminology but associate the 

terms cruising, prolonged, or burst swimming behaviors in parentheses as applied to the author’s 

usage. These three terms have physiological definitions consistent among fisheries scientists that 

relate to the use of energy reserves leading to fatigue. Specifically, the time for 50% of the test 

subjects to fatigue (unable to maintain position in a current), expressed as swimming speed in body 

lengths per second, distinguishes among the three types of swimming behavior (Beamish 1978). 

Cruising can be sustained nearly indefinitely, burst swimming leads to the most rapid fatigue, and 

prolonged swimming is intermediate between the two (EPRI 2000). 

Cruising and prolonged swimming, which are used more by larger fish than by larvae, are both 

essentially continuous modes of swimming. Burst swimming is the mode most characteristic of 

larvae, and it differs from the other two modes by incorporating substantial periods of rest between 

very short bursts of active swimming. During the resting intervals between the bursts, the forward 

motion may be sustained briefly as a glide if the larva is large enough for its momentum to overcome 

the resistance of the water. Then the mode of burst swimming can be described as “beat and glide” 

swimming (Weihs 1980) or “beat-and-coast” swimming (Webb and Weihs 1986). However, the 

potential for gliding during the rest intervals of burst swimming is limited by the ratio of inertial to 

frictional forces, expressed by the Reynolds number (Weihs 1980). For a very small (newly hatched) 

larva, the Reynolds number is too low to permit gliding between bursts. In addition, a bulky yolk sac 

is a further impediment to gliding during the first few days after hatching, so yolk-sac larvae are 

ineffectual swimmers. After the yolk sac is absorbed, the increasing size and speed of the growing 

larva eventually raise the Reynolds number enough to make gliding possible. This transition between 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 57 Normandeau Associates, Inc.

burst swimming with no gliding to burst swimming with gliding takes place between the lengths of 5 

and 15 mm for northern anchovy larvae (Weihs 1980). 

Blaxter (1986) summarized the capabilities acquired early during development of larval fish that 

provide them with the ability to detect a threat and initiate evasive action. Soon after hatching, eyes 

and neuromasts (sensory cells on the lateral surface of the body) are sufficiently well developed to 

enable larvae to react to visual and mechanical stimuli. Larvae can swim up to 20 body lengths 

(“BL”) per second for very short periods (bursts) and 10-20 BL/s for longer periods (prolonged). 

Some species can maintain 4-5 BL/s for prolonged periods (e.g., 30 min), and cruising speeds of 1-3 

BL/s can be maintained indefinitely. 

Eaton and DiDomenico (1986) noted that the escape response in fish appears very early during 

development, as early as 44 hours after fertilization, even before normal hatching begins. The typical 

startle response incorporates a “C-type fast start” (burst) enabling the young fish to swim a distance 

equal to its body length in about 100 milliseconds (“ms”; i.e., 10 body lengths per second). While 

this behavior is primarily a predator avoidance response, it does demonstrate that an extremely rapid 

acceleration is possible at a very young stage. Webb and Weihs (1986) reported that during “beatand-coast” swimming (i.e., burst and cruise swimming), larval northern anchovy (a West Coast 

species) have a maximum (burst) speed exceeding 10 BL/s. Measurements of burst swimming speed 

by Fuiman (1986) for zebra danio larvae averaging 3.6 mm in length indicated that some of the earlier 

estimates of burst speed may be conservatively low. He observed burst speeds that reached 15 cm/s 

within 20 ms, the equivalent of 40-50 BL/s. 

Miller et al. (1988) summarized burst swimming in a relationship between length (“L”) in mm and 

speed (“S”) in cm/s where S=3.33+0.71 L. This equates to about 10 cm/s (10 BL/s) for a 10-mm 

larva, faster than the through-slot velocity of 7.6 cm/s (0.25 ft/s) that is within the range under 

consideration for IPEC’s CWW screens. 

For the typical larval swimming mode (burst swimming), the following table shows the burst 

swimming speed in cm/s at 10 BL/s (Eaton and DiDomenico 1986, Webb and Weihs 1986, and 

Miller et al. 1988), 20 BL/s (Blaxter 1986), and 40 BL/s (Fuiman 1986) related to the typical species 

and sizes of fish larvae exposed to entrainment at IPEC: 

Taxon Quartile 

Total 

Length 

(mm) 

Swimming speed (cm/sec) 

Burst 

@ 10 BL/sec 

Burst 

@ 20 BL/sec 

Burst 

@ 40 BL/sec 

Striped bass 

 

25% 6.2 6.2 12.4 24.8 

50% 7.4 7.4 14.8 29.6 

75% 8.6 8.6 17.2 34.4 

White perch 

 

25% 5.4 5.4 10.8 21.6 

50% 7.1 7.1 14.2 28.2 

75% 10.4 10.4 20.8 41.6 

River herring 

 

25% 9.3 9.3 18.6 37.2 

50% 11.9 11.9 23.8 47.6 

75% 14.3 14.3 28.6 57.2 

Bay anchovy 

 

25% 9.1 9.1 18.2 36.4 

50% 13.8 13.8 27.6 55.2 

75% 17.0 17.0 34.0 68.0 

These data illustrate that the average (50% quartile) Hudson River fish larva exposed to entrainment 

at IPEC can swim briefly (burst) at a speed of between 7.1 and 13.8 cm/sec (0.23-0.45 feet/sec) 

depending on the taxon, at the conservative estimate of 10 BL/s. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 58 Normandeau Associates, Inc.

Relationships between length and swimming speed for larger fish (50 mm and larger) presented by 

Videler (1993) are consistent with the estimates for larvae: S=0.15+2.4 L for sustained (cruising) 

swimming, S=0.61+2.4 L for prolonged swimming, and S=0.4+7.4 L for burst swimming (where 

speed is in m/s and length is in m). The smaller the fish, the faster the swimming speed in terms of 

body lengths per second. The smallest fish upon which these relationships were based represent the 

approximate entrainment-to-impingement transition size for 3/8-inch mesh screens, but extrapolating 

the equations to smaller fish implies that burst speed for PYSL could be at least 10 BL/s and the 

prolonged swimming speed could be faster than the proposed 7.6 cm/s intake velocity. 

EPRI (2000) conducted a literature review and evaluation to determine whether intake approach 

velocities of no more than 0.5 ft/s can prevent impingement impacts of CWIS. Their evaluation 

focused on the prolonged swimming speeds of impingeable size juveniles and adults near 

conventional intakes (the speed of continuous swimming that can be maintained for a prolonged 

period of time before the fish fatigues such as when forced to hold position in an intake current; as 

opposed to burst speeds or indefinitely sustainable “cruising” speeds). Most data presented were for 

fish too large to be vulnerable to entrainment through fine-mesh or CWW screens, but critical 

swimming speeds for some of the smaller fish may be applicable to IPEC. Critical swimming speeds 

for bay anchovy included 10 cm/s at 28 mm, 11.9 cm/s at 33 mm, and 17.7 cm/s at 34 mm; prolonged 

swimming speeds for Atlantic menhaden included 17-21 cm/s at 36 mm; and critical swimming 

speeds for striped bass included 35 cm/s at 25 mm. Impingement of bay anchovy and Atlantic 

menhaden in large numbers in estuaries was attributed to median swimming speeds at or below 0.5 

ft/s at lengths around 30 mm. If, however, the intake flow at IPEC were to be reduced to 0.25 ft/s 

(7.6 cm/s), then even the typically vulnerable species such as bay anchovy and Atlantic menhaden 

may be able to avoid entrainment. 

References

Beamish, F.W.H. 1978. Swimming capacity. Pages 101-187, in W.S. Hoar and D.J. Randall, eds. 

Fish Physiology. Volume VII. Locomotion. Academic Press, New York. 

Blaxter, J.H.S. 1986. Development of sense organs and behaviour of teleost larvae with special 

reference to feeding and predator avoidance. Trans. Amer. Fish. Soc. 115(1):98-114. 

Breder, C. M. 1926. The locomotion of fishes. Zoologica 4: 159-256. 

Clutter, R.I., and M. Anraku. 1968. Avoidance of samplers. Pages 57-76 in D.J. Tranter (ed), 

Zooplankton sampling. UNESCO Monographs on oceanographic methodology, No. 2. 

Eaton, R.C., and R. DiDomenico. 1986. Role of the teleost escape response during development. 

Trans. Amer. Fish. Soc. 115(1):128-142. 

EPRI (Electric Power Research Institute). 2000. Technical evaluation of the utility of intake 

approach velocity as an indicator of potential adverse environmental impact under Clean Water 

Act Section 316(b). Report 1000731. 

Fuiman, L.A. 1986. Burst-swimming performance of larval zebra danios and the effects of diel 

temperature fluctuations. Trans. Amer. Fish. Soc. 115(1):143-148. 

Hammer, C. 1995. Fatigue and exercise tests with fish. Comparative Biochemistry and Physiology 

A 112: 1-20. 

Miller, T.J., L.B. Crowder, J.A. Rice, and E.A. Marschall. 1988. Larval size and recruitment 

mechanisms in fishes: toward a conceptual framework. Can. J. Fish. Aquat. Sci. 45(9):1657-

1670. 

Videler, J.J. 1993. Fish swimming. Fish and fisheries series 10. Chapman and Hall, London, UK. 
IPEC Alternatives Analysis

Appendix B 2-1-10.DOC, 2/2/10 59 Normandeau Associates, Inc.

Webb, P.W., and D. Weihs. 1986. Functional locomotor morphology of early life history stages of 

fishes. Trans. Amer. Fish. Soc. 115(1):115-127. 

Weihs, D. 1980. Energetic significance of changes in swimming modes during growth of larval 

anchovy, Engraulis mordax. Fish. Bull., U.S. 77(3):597-604. 
Appendix C 

Empirical Assessment of Expected Population-Level Effects of 

Reductions in Entrainment Losses at Entergy Nuclear Indian Point Units 2 and 3 

February 2010 

Prepared by 

AKRF, Inc. 

7250 Parkway Drive 

Suite 210 

Hanover, Maryland 21076 
1 

INTRODUCTION 

 Entergy Nuclear Indian Point 2, LLC and Entergy Nuclear Indian Point 3, LLC 

(“Entergy”) retained AKRF, Inc. to evaluate the population-level effects of reductions in 

entrainment losses associated with certain alternative intake technologies considered as part 

of Entergy’s alternative technology assessment undertaken pursuant to the New York State 

Department of Environmental Conservation (“NYSDEC”) Assistant Commissioner’s August 

13, 2008 Interim Decision.1 This report supports the “Biological Effectiveness of Alternative 

Intake Technologies for Indian Point Units 2 and 3” (the “Biological Report”) prepared by 

Lawrence W. Barnthouse of LWB Environmental Services, Inc., Douglas G. Heimbuch of 

AKRF, Inc., Mark T. Mattson of Normandeau Associates, Inc., and John R. Young of ASA 

Analysis & Communication, Inc. 

Changes in population abundance resulting from reductions in entrainment losses 

caused by alternative intake technologies cannot be determined by calculating age-1 

equivalents. As noted in the Biological Report, projected benefits of alternative intake 

technologies, measured as reductions in entrainment losses, have been expressed in terms of 

potential annual increases in age-1 equivalents (USEPA, 2006; Enercon Services, Inc., 2010). 

In the calculation of age-1 equivalents, entrainment losses for each life stage (i.e. eggs, 

larvae, yolk-sac larvae, post-yolk sac larvae, juvenile fish, and fish) are converted into 

equivalent one-year-old fish. Conversion to age-1 equivalents enables an analysis because 

entrainment losses for each alternative intake technology evaluated can be expressed in terms 

of a common metric. Although a convenient metric for summarizing entrainment losses that 

occur over several life stages (primarily eggs and larvae), the calculated age-1 equivalents do 

not provide any indication of the actual changes in age-1 population abundance that likely 

would result due to the reduction in entrainment losses. These estimates are theoretical 

calculations based on estimates of the average fraction of entrained fish that would have 

survived to an age of 1 year. As shown in the AEI Report, however, survival rates of early 

life stages of fish in the Hudson River are highly variable, and correlations between these 

survival rates and abundance indices for larvae and juveniles are often low. Hence, 

increasing the abundance of larvae through reductions in entrainment losses may lead to little 

or no increase in the abundance of older fish. To assess the likely changes in fish population 

abundance that correspond to calculated increases in age-1 equivalents, field measurements 

 

1

 As noted in Biological Effectiveness of Alternative Intake Technologies for Indian Point Units 2 and 3 

(Barnthouse et al. 2010), a 2003 draft permit issued by NYSDEC Staff proposed modifications to the cooling 

water intake structure at Entergy’s Indian Point Entergy Center (“IPEC”) nuclear powered electric generating 

stations 2 and 3 (individually, “Unit 2” and “Unit 3,” and collectively, the “Stations”). These modifications 

include possible construction and operation of two large counter-flow, forced draft, plume abated hybrid 

cooling towers (the “NYSDEC Proposed Project”). Counsel for Entergy also informed AKRF that 

consideration of the NYSDEC Proposed Project is subject to an alternative technologies assessment. 

Accordingly, the Department may revisit its proposed modifications to the draft SPDES permit for the 

Stations and change them pursuant to Entergy’s alternative technologies assessment. 
2 

of changes in fish population abundance corresponding to actual increases in larval 

abundance (expressed in terms of increases in age-1 equivalents) would be needed. 

 Field measurements of changes in juvenile abundance in response to increases in 

larval abundance have been recorded by the Long River Survey (“LRS”), Beach Seine 

Survey (“BSS”), and Fall Juvenile Survey (“FJS”) for over 30 years on the Hudson River 

(field data documented in annual “Year Class Reports”, e.g. EA, 1996). The historical data 

document what can be viewed as naturally-occurring experiments (i.e., the response of 

abundance at the juvenile lifestage to a change in abundance at the larval lifestage)of the 

effects of increases in riverwide post-yolk sac larva (“PYSL”) abundance (that can be 

expressed in terms of age-1 equivalents) on changes in riverwide juvenile abundance. Those 

naturally-occurring experiments can be used to address the question of what demonstrable 

changes in fish populations can be expected from reducing entrainment losses at the IPEC 

Stations. 

METHODS 

Overview 

 To address the objective of this assessment, the relationship between increases in 

PYSL abundance and changes in abundance of older fish was characterized for American 

shad, river herring (alewife and blueback herring, collectively), striped bass, white perch, 

Atlantic tomcod, and bay anchovy. These are seven of the eight representative important 

species (“RIS”) studied in the Biological Report. Spottail shiner was not included in this 

assessment because, as noted in the AEI Report, the LRS sampling program does not 

adequately sample larval spottail shiner. For each of the seven species under consideration, 

the annual riverwide PYSL abundance, expressed in terms of age-1 equivalents, was 

calculated for each year from 1974 through 2005. All pairs of years (i,j)were listed, and the 

change in abundance from year i to year j, for each pair of years was recorded: 

PYSLi, j N1,i N1, j

~ ~    (1) 

where 

PYSLi, j = the change in PYSL abundance between years i and j, expressed in 

terms of age-1 equivalents, 

N1,i

~ = PYSL abundance in year, i, expressed in terms of age-1 equivalents, and 

N1, j

~ = PYSL abundance in year, j, expressed in terms of age-1 equivalents. 

Next, all pairs of years in which PYSL abundance was greater in year j than in year i (i.e., 

i, j  0) were identified. With 32 years of abundance estimates, there were 1,024 pairs of 

years, of which 496 had an increase in PYSL abundance in year j as compared to year i (and 

496 pairs had a decrease in PYSL abundance, and 32 pairs had no change). Evaluating all 
3 

pairs of years, rather than only adjacent years, eliminates any possible influence of long-term 

trends in abundance or survival of larvae on the outcome of the analysis, thereby eliminating 

potential confounding effects of trends in environmental conditions (un-related to Station 

operation). 

 For each pair of years with an increase in PYSL abundance, the corresponding change 

in observed juvenile abundance was calculated. For each species, estimates of changes in 

juvenile abundance were based on the annual juvenile index of abundance from the AEI 

Report. To eliminate the effect of uncertain gear efficiencies (i.e., the proportion of fish in 

front of a sampling net that is actually collected by the net) on the magnitude of juvenile 

abundance index values, the indices of juvenile abundance were standardized to the average 

(over all years of data listed below for each species) juvenile index value for each species. 

For river herring, striped bass and white perch, the juvenile indices were based on the Beach 

Seine Survey from 1974-2005. For American shad, the juvenile index was based on the Fall 

Shoals Survey from 1985-2005 (years with beam trawl sampling). Accordingly, the 

assessment for American shad only addressed the 441 pairs of years from 1985-2005 (210 of 

which had increases in PYSL abundance). 

Changes in juvenile abundance were expressed in terms of multiples of the long-term 

average juvenile abundance index value: 

JI

JI JI

JUV i j

i j

   *

, (2) 

where 

*

i, j JUV = the change in juvenile abundance between years i and j, relative to the 

long-term average juvenile abundance, 

i JI = the juvenile abundance index value in year i, 

j JI = the juvenile abundance index value in year j, and 

JI = the long-term average value of the juvenile abundance index. 

 The estimates of increases in PYSL abundance, expressed in terms of age-1 

equivalents, were computed using the same methods used to express reductions in 

entrainment losses in terms of age-1 equivalents (ASAAC, 2009). Therefore, the estimates 

of increases in PYSL abundance are directly comparable to the projections of potential 

increases in age-1 equivalents due to reduced entrainment losses. The projected range of 

potential annual increases in age-1 equivalents due to eliminating current entrainment losses 

resulting from the Stations (Table 1, reproduced from ASAAC, 2009) were compared to the 

range of year-to-year increases in riverwide age-1 equivalents. For those year-to-year 

increases in riverwide age-1 equivalents that fell within the range of potential annual 
4 

increases in age-1 equivalents due to eliminating current entrainment losses associated with 

the Stations’ operation, the corresponding changes in juvenile abundance were summarized. 

The changes in juvenile abundance for those pairs of years indicate the change in juvenile 

abundance that could be expected if current entrainment losses associated with operation of 

the Stations were eliminated. 

Estimation of PYSL Abundance 

 For each species, the annual riverwide post yolk sac larval abundance, expressed in 

terms of age-1 equivalents, was calculated from an estimate of the number of organisms 

entering the post yolk sac larval lifestage (USEPA, 2006): 

ZPYSL ZJUV

y y N N e e ˆ ˆ

1, 0, ˆ ~    (3) 

where 

N1, y

~ = the calculated age-1 equivalents based on an estimate of the number of 

organisms that enter the PYSL lifestage, 

N0, y ˆ = an estimate of the number of organisms that enter the PYSL lifestage, 

Z PYSL

ˆ = an estimate of the instantaneous mortality rate for the PYSL lifestage, 

and 

ZJUV

ˆ = an estimate of the instantaneous mortality rate for the juvenile lifestage. 

Each estimate of the number of organisms entering the post yolk sac larval lifestage was 

based on reported estimates of riverwide standing crops from the Long River Survey (e.g., 

see EA, 1996), and on the following relationship between average abundance over an interval 

of time and the number of organisms at the beginning of the interval (Ricker, 1975): 

 

Z

e N N

Z   1

0 (4) 

and 

  Z

e

Z N N    1 0 (5) 

where 

N = the average number of organisms alive (e.g., per day) during an interval 

of time over which the organisms experience mortality, 

N0 = the number of organisms alive at the beginning of the interval, and 

Z = instantaneous mortality rate during the interval. 

For each daily cohort, the average PYSL abundance can be represented in terms of the 

number alive and still in the PYSL lifestage on each day of the sampling season: 
5 





T

t

c t

PYSL

c N

D

N

1

,

1 (6) 

where 

Nc = the average number of cohort, c, organisms alive (per day) during the 

interval from the first day cohort, c, entered the PYSL lifestage to the last 

day cohort, c, was in the PYSL lifestage, 

Nc,t = the number of cohort, c, organisms alive on day, t, 

D PYSL = the PYSL lifestage duration (days), and 

T = the duration of the sampling season (days). 

noting that DPYSL < T, and that Nc,t is zero on all days during which cohort c is not in the 

PYSL lifestage (i.e., cohort c is in the YSL or juvenile lifestage). 

 

 Because PYSL are not identified to individual daily cohorts by the LRS sampling 

program (only the total number of PYSL are reported), equation (6) was summed over all 

daily cohorts. Summing over cohorts allows the average PYSL abundance to be represented 

in terms of the average daily abundance of PYSL during the sampling season as: 

*

1

,

1 1 N

D

T N

D

N

D

N N

PYSL

T

t

t

c PYSL

T

t

c t

c PYSL

  c       (7) 

where the average daily PYSL abundance over the sampling season is: 





T

t

Nt TN

1

* 1 (8) 

and 

Nt = the number of PYSL alive on day, t, and 

* N = the average number alive, per day, during the sampling season. 

Substituting equation (7) into equation (5) gives the following formula for estimating the 

number of organisms entering the PYSL lifestage based on reported standing crop estimates 

from the Long River Survey: 

  *

0, ˆ

ˆ

1

ˆ ˆ y

PYSL

y

Z

PYSL

y N

D

T

e

Z

N  PYSL   (9) 

where hats (^) indicate estimates for the corresponding parameters. 
6 

 This method is based on the assumption that the full spatial and temporal extent of 

PYSL presence was subject to sampling. To test this assumption, the spatial and temporal 

patterns of PYSL abundance, in relation to the regions and weeks sampled by the LRS, were 

examined for each target taxon (i.e., American shad, Atlantic tomcod, bay anchovy, river 

herring, striped bass and white perch). The spatial pattern of PYSL abundance was 

expressed in terms of the relative abundance in each of the 13 regions of the Hudson River 

(from the Battery to the Federal Dam at Troy) during in the sampling season (ASAAC 2009). 

A spatial pattern characterized by low relative abundance at the southern boundary of the 

spatial extent of sampling, i.e., in regions 0 (Battery) and 1 (Yonkers), and high relative 

abundance elsewhere in the River was considered evidence that most of the population was 

upstream of the southern boundary; and therefore, the LRS adequately sampled the spatial 

extent of PYSL for a species. However, a spatial pattern characterized by high relative 

abundance in regions 0 and 1, and low relative abundance elsewhere in the River was 

considered evidence that a substantial portion of the PYSL likely were downstream of the 

southern boundary; and therefore, may have missed by LRS sampling. Similarly, a temporal 

pattern characterized by an increase in abundance followed by a decrease in abundance 

during the sampling season was considered evidence that the sampling season bracketed the 

period of PYSL presence. However, a temporal pattern characterized by greatest abundance 

occurring at the beginning or end of the sampling period was considered evidence that the 

sampling season may have missed the period of highest PYSL abundance. 

 American shad, river herring, striped bass and white perch exhibited spatial patterns 

of PYSL abundance that indicated the LRS sampling program adequately sampled the spatial 

extent of PYSL presence (Figures 1-4). However, spatial pattern of PYSL bay anchovy and 

Atlantic tomcod indicated a substantial portion of the PYSL population may have been 

outside the area subject to sampling by the LRS (Figures 5 and 6). American shad, river 

herring, striped bass, white perch, and bay anchovy exhibited temporal patterns of PYSL 

abundance that indicated the LRS sampling program adequately sampled the temporal extent 

of PYSL presence (Figures 7-11). However, the temporal pattern of PYSL Atlantic tomcod 

indicated the LRS sampling season generally occurred too late to capture the full period of 

PYSL Atlantic tomcod presence (Figure 12). 

 Based on these results Atlantic tomcod and bay anchovy were excluded from further 

analysis. For the remaining four taxa (American shad, river herring, striped bass and white 

perch), annual estimates of PYSL average abundance during the sampling season from AEI 

Report (Barnthouse, et al 2008) were used for the analysis in equation (9). Those estimates 

were based on LRS data from weeks 18 through 26 (the weeks consistently sampled by the 

LRS in all years, 1974-2005). 

Expected Changes in Juvenile Abundance 

 For those year-to-year increases in PYSL abundance with riverwide age-1 equivalents 

that fell within the range of potential annual increases in age-1 equivalents due to eliminating 

entrainment losses associated with current operation of the Stations, the corresponding 
7 

changes in juvenile abundance were summarized. Expected changes in juvenile abundance 

were characterized in terms of the probability that the change would be an increase in 

juvenile abundance, and in terms of the expected magnitude of change in juvenile abundance. 

 The probability (P) that the change in juvenile abundance would be an increase was 

estimated as: 

n

x Pˆ  (10) 

n = the number of pairs of years (i’,j’) that satisfied the criterion of a PYSL 

abundance increase within the range of potential annual increases in age-1 

equivalents due to eliminating current IPEC entrainment losses, and 

x = of those pairs of years, the number of pairs of years with increases in juvenile 

abundance. 

A non-parametric Sign test (Kendall and Stuart, 1979) was used to test the hypothesis that the 

underlying probability of an increase in juvenile abundance was 0.5 (i.e., a decrease in 

abundance was just as likely as an increase in abundance). In addition, exact 95% binomial 

confidence limits (Beyer, 1968) for the estimate of the probability of an increase in juvenile 

abundance were calculated. 

 For each species, the expected magnitude of change in juvenile abundance was 

calculated as the average of changes in juvenile abundance over the n pairs of years: 

 



   , ', '

*

,

~ 1

i j i j

Juv i j JUV

n

 (11) 

and an approximate 95% confidence interval was calculated as: 

  Juv n Juv   t  s e 

~ . . ~ 1 . (12) 

where 

   

( 1)

~

~ . . , ', '

2 *

,



  

 



n n

JUV

s e

i j i j

i j Juv

Juv (13) 

and tn-1 is the t-statistic with n-1 degrees of freedom. This approximation does not explicitly 

account for covariance associated with individual years that were included in more than one 

pair of years. Therefore, the widths of the approximate confidence intervals are likely to be 

underestimates. 
8 

RESULTS 

 For each of the 4 taxa (American shad, river herring, striped bass and white perch), 

the projected range of potential annual increases in age-1 equivalents due to eliminating 

current entrainment losses associated with the Stations’ operation is very small compared to 

the range of year-to-year increases in riverwide PYSL abundance calculated from historical 

data (Figures 13 through 16). Within the projected range of potential annual increases in 

age-1 equivalents due to eliminating current entrainment losses associated with the Stations’ 

operation, the estimated probability of observing an increase in juvenile abundance is not 

significantly different than 50:50 for any of the 4 taxa (Table 2). Within that range, the 

estimated average annual change in juvenile abundance is not significantly different from 

zero for any of the 4 taxa (Table 3). 

CONCLUSIONS 

 The metric of potential increases in equivalent age-1 abundance was used in the 

Biology Report to compare the efficacies of alternative intake technologies at reducing 

entrainment losses associated with current operation of the IPEC Stations. Although a 

convenient metric for comparing the efficacies of alternative intake technologies, the 

calculated age-1 equivalents cannot be used to predict changes in the abundance of age-1 fish 

at the species population level. The results from this assessment show that historical 

increases in PYSL abundance, of the magnitude that is projected will occur by eliminating 

current entrainment losses associated with the Stations’ operation, did not result in 

corresponding increases in juvenile abundance (the lifestage immediately preceding age-1). 

Rather, the juvenile abundance was just a likely to decline as increase, and the average 

change in juvenile abundance was not significantly different from zero. 

 Based on: (1) empirical relationships between year-to-year increases in riverwide 

PYSL abundance (expressed in terms of age-1 equivalents) and year-to-year changes in 

riverwide juvenile abundance, and (2) the projected ranges of relatively small potential 

increases in age-1 equivalents due to eliminating current entrainment losses associated with 

IPEC Stations’ operation, no alternative intake technology considered as part of Entergy’s 

alternative technology assessment would be expected to result in a demonstrable increase in 

juvenile abundance of American shad, river herring, striped bass or white perch. 

 The results and conclusion of this assessment are consistent with the results and 

conclusions of the AEI Report (Barnthouse, et al, 2008), which used a completely different 

set of methods to demonstrate that historical operations of the IPEC Stations have had no 

measurable effect on fish populations in the Hudson River. 
9 

REFERENCES 

ASA Analysis and Communication (ASAAC). 2009. Biological analysis of selected cooling 

system alternatives for Indian Point Energy Center. 

Barnthouse, L.W., D.G. Heimbuch, W. Van Winkle, and J. Young. 2008. Entrainment and 

Impingement at IP2 And IP3: A Biological Impact Assessment. 

Beyer, W.H. 1968. Handbook of tables for Probability and Statistics (2nd

 ed). CRC Press, 

Inc. Cleveland. 642 pp. 

EA Engineering, Science and Technology (EA). 1996. 1995 year class report for the 

Hudson River estuary monitoring program. Prepared for Consolidated Edison 

Company of New York, Inc. New York, New York. 

Enercon Services, Inc. 2010. Evaluation of alternative intake technologies at Indian Point 

Units 2 & 3. Prepared for Entergy Nuclear Indian Point 2, LLC, and Entergy Nuclear 

Indian Point 3, LLC. 

Kendall, M. and A. Stuart. 1979. The Advanced Theory of Statistics: Volume 2 (4th

 ed). 

Charles Griffin & Company Ltd, London. 748 pp. 

Ricker, W.E. 1975. Computation and interpretation of biological statistics of fish 

populations. Bulletin of the Fisheries Research Board of Canada. Bulletin 191. 382 p. 

Department of the Environment, Fisheries and Marine Service. Ottawa. 

USEPA. 2006. Regional Benefits Analysis for the Final Section 316(b) Phase III Existing 

Facilities Rule. U.S. Environmental Protection Agency, Office of Water, 

Washington, DC. EPA-821-R-04-007. 
10 

Table 1. Projected annual increases in of age-1 equivalents due to eliminating current 

entrainment losses associated with IPEC Stations’ operation (ASAAC, 2009). 

Taxon1

 Projected Range of Potential 

Annual Increases in Age-1 

Equivalents Due to Eliminating 

Current Entrainment Losses From 

IPEC Units 2 and 3 

Minimum 

Projected 

Annual 

Increase in 

Age-1 

Equivalents 

Maximum 

Projected 

Annual Increase 

in Age-1 

Equivalents 

River Herring 12,100 86,900 

American Shad <1 200 

Striped Bass 76,300 561,400 

White Perch 54,100 347,200 

 

1

 Bay anchovy and Atlantic tomcod were not included in the analysis because available data on the spatial and 

temporal distributions of these species indicated the LRS may not have adequately sampled the full spatial and 

temporal extent of PYSL presence. 
11 

Table 2. Probabilities of increases in juvenile abundance corresponding to observed year-toyear increases in PYSL abundance (expressed in terms of age-1 equivalents) in the 

Hudson River that were within the projected range of potential annual increases in 

age-1 equivalents due to eliminating entrainment losses associated with current 

Stations’ operation. 

Taxon1

 Number of 

Pairs of 

Years with 

Increase in 

PYSL 

Abundance 

that 

Satisfied the 

Criteria 

(n) 

Number of 

Those Pairs 

of Years 

with 

Increase in 

Juvenile 

Abundance 

(x) 

Critical 

Value (k) 

for Sign 

Test 

H0: P=0.5 

Reject H0 if 

x<k

or 

x>(n-k) 

Probability of Increase in Annual Juvenile 

Abundance 

Estimate Lower 95% 

Confidence 

Limit 

Upper 95% 

Confidence 

Limit 

River Herring 24 11 7 0.46 0.26 0.67 

American Shad 6 2 0 0.33 0.04 0.78 

Striped Bass 87 44 35 0.51 0.40 0.61 

White Perch 14 10 3 0.71 0.41 0.92 

 

1

 Bay anchovy and Atlantic tomcod were not included in the analysis because available data on the spatial and 

temporal distributions of these species indicated the LRS may not have adequately sampled the full spatial and 

temporal extent of PYSL presence. 
12 

Table 3. Expected change in magnitude of juvenile abundance corresponding to observed 

year-to-year increases in PYSL abundance (expressed in terms of age-1 equivalents) 

in the Hudson River that were within the projected range of potential annual increases 

in age-1 equivalents due to eliminating entrainment losses associated with current 

Stations’ operation. 

Taxon1

 Average Annual Change in Juvenile 

Abundance 

(as % of Historical Average Juvenile 

Abundance) 

Estimate Lower 95% 

Confidence 

Limit 

Upper 95% 

Confidence 

Limit 

River Herring +10% -35% +55% 

American Shad -13% -46% +19% 

Striped Bass +10% -7% +27% 

White Perch +20% -27% +67% 

 

1

 Bay anchovy and Atlantic tomcod were not included in the analysis because available data on the spatial and 

temporal distributions of these species indicated the LRS may not have adequately sampled the full spatial and 

temporal extent of PYSL presence. 
13 

Figure 1. Spatial pattern of abundance of PYSL American shad in the Hudson River. Based 

on LRS data from 1974-2005. 

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0 1 2 3 4 5 6 7 8 9 10 11 12

Region

R

e

l

a

t

i

v

e

D

e

n

s

i

t

y

O

b

s

e

r

v

e

d

i

n

E

a

c

h

R

e

g

i

o

n

o

f

S

a

m

p

l

i

n

g

American Shad
14 

Figure 2. Spatial pattern of abundance of PYSL river herring in the Hudson River. Based on 

LRS data from 1974-2005. 

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0 1 2 3 4 5 6 7 8 9 10 11 12

Region

R

e

l

a

t

i

v

e

D

e

n

s

i

t

y

O

b

s

e

r

v

e

d

i

n

E

a

c

h

R

e

g

i

o

n

o

f

S

a

m

p

l

i

n

g

River Herring
15 

Figure 3. Spatial pattern of abundance of PYSL striped bass in the Hudson River. Based on 

LRS data from 1974-2005. 

0.00

0.05

0.10

0.15

0.20

0.25

0 1 2 3 4 5 6 7 8 9 10 11 12

Region

R

e

l

a

t

i

v

e

D

e

n

s

i

t

y

O

b

s

e

r

v

e

d

i

n

E

a

c

h

R

e

g

i

o

n

o

f

S

a

m

p

l

i

n

g

Striped Bass
16 

Figure 4. Spatial pattern of abundance of PYSL white perch in the Hudson River. Based on 

LRS data from 1974-2005. 

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Figure 5. Spatial pattern of abundance of PYSL bay anchovy in the Hudson River. Based on 

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region 0). 

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Figure 6. Spatial pattern of abundance of PYSL Atlantic tomcod in the Hudson River. 

Based on LRS data from 1995-2005 (years with sampling beginning by week 9, and 

sampling of region 0). 

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Figure 7. Temporal pattern of abundance of PYSL American shad in the Hudson River. 

Based on LRS data from 1974-2005. 

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Figure 8. Temporal pattern of abundance of PYSL river herring in the Hudson River. Based 

on LRS data from 1974-2005. 

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Figure 9. Temporal pattern of abundance of PYSL striped bass in the Hudson River. Based 

on LRS data from 1974-2005. 

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Figure 10. Temporal pattern of abundance of PYSL white perch in the Hudson River. Based 

on LRS data from 1974-2005. 

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Figure 11. Temporal pattern of abundance of PYSL bay anchovy in the Hudson River. 

Based on LRS data from 1991-2005 (years with sampling through week 40, and 

sampling of region 0). 

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Figure 12. Temporal pattern of abundance of PYSL Atlantic tomcod in the Hudson River. 

Based on LRS data from 1995-2005 (years with sampling beginning by week 9, and 

sampling of region 0). 

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-3-2-1

0123

0

2,500 5,000 7,500 10,000 12,500 15,000 17,500 20

Projected Range of Potential Annual Increase in Age-1 EquivalentsDue to Eliminating Current IPEC Entrainment Losses

Observed Year-to-Year Increase in PYSL Abundance

(Expressed as Increase in Equivalent Age-1 Abundance)

ObservedChangeinJuvenileAbundance

(ExpressedasaMultipleofAverageJuvenileAbundance) American Shad

Figure 13. Observed year-to-year changes in riverwide juvenile abundance of American shad in response to obse

increases in riverwide PYSL abundance. Based on all pairs of years (1985-2005) with observed positive 

abundance. 
26 

-4-3-2-1

01234

0200,000400,000600,000800,000 1,000,000 1,200,000 1,400,000 1,600,000 1,800,000 2,000,000 2,200,000 2,400,000 2,600,000 

Projected Range of Potential Annual Increase in Age-1 EquivalentsDue to Eliminating Current IPEC Entrainment Losses

Observed Year-to-Year Increase in PYSL Abundance

(Expressed as Increase in Equivalent Age-1 Abundance)

ObservedChangeinJuvenileAbundance

(ExpressedasaMultipleofAverageJuvenileAbundance) River Herri

Figure 14. Observed year-to-year changes in riverwide juvenile abundance of river herring in response to observ

increases in riverwide PYSL abundance. Based on all pairs of years (1974-2005) with observed positive 

abundance. 
27 

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Projected Range of Potential Annual Increase in Age-1 EquivalentsDue to Eliminating Current IPEC Entrainment Losses

Observed Year-to-Year Increase in PYSL Abundance

(Expressed as Increase in Equivalent Age-1 Abundance)

ObservedChangeinJuvenileAbundance

(ExpressedasaMultipleofAverageJuvenileAbundance) Striped Bas

Figure 15. Observed year-to-year changes in riverwide juvenile abundance of striped bass in response to observe

increases in riverwide PYSL abundance. Based on all pairs of years (1974-2005) with observed positive 

abundance. 
28 

-3-2-1

0123

0

5,000,00010,000,00015,000,00020,000,00025,000,00030,000,00035,000,00

Projected Range of Potential Annual Increase in Age-1 EquivalentsDue to Eliminating Current IPEC Entrainment Losses

Observed Year-to-Year Increase in PYSL Abundance

(Expressed as Increase in Equivalent Age-1 Abundance)

ObservedChangeinJuvenileAbundance

(ExpressedasaMultipleofAverageJuvenileAbundance) White Per

Figure 16. Observed year-to-year changes in riverwide juvenile abundance of white perch in response to observe

increases in riverwide PYSL abundance. Based on all pairs of years (1974-2005) with observed positive 

abundance. 
Appendix D

Responses to Issues Raised in NYSDEC’s FEIS

Lawrence W. Barnthouse, Ph. D. 

LWB Environmental Services, Inc. 

February 2010 
1

 In the Final Environmental Impact Statement for State Pollution Discharge 

Elimination System (“SPDES”) permit renewals at the Roseton 1 & 2, Bowline 1& 2, and 

Indian Point 2 & 3 steam electric generating stations (the “FEIS”), the New York State 

Department of Environmental Conservation (“NYSDEC”) raised issues concerning the 

impacts of entrainment and impingement on fish populations and communities that were 

not addressed in the Draft Environmental Impact Statement (the “DEIS”) prepared by the 

Hudson River utility companies. Many of these issues were initially raised in a review of 

the DEIS prepared for NYSDEC by ESSSA Technologies, Inc. (ESSA 2000). 

 This attachment documents a re-evaluation of these issues by Entergy Nuclear 

Indian Point 2, LLC and Entergy Nuclear Indian Point 3, LLC (collectively “Energy”) 

and provides further support for the conclusion reached in Entergy’s Adverse 

Environmental Impacts (“AEI”) Report (Barnthouse et al. 2008) that historical operations 

of Indian Point Energy Center (“IPEC”) Units 2 and 3 have not adversely affected fish 

populations and communities in the Hudson River.1

D.1 Correction of errors and misinterpretations in ESSA/Deriso 

critiques of the DEIS 

ESSA (2000) conducted a review of the DEIS on behalf of NYSDEC, identifying 

a number of purported weaknesses in the DEIS. The purpose of this section is to evaluate 

the relevance of ESSA’s review in light of Entergy’s January 2008 AEI Report and other 

current documents, and to correct some errors made in ESSA’s review. Many of ESSA’s 

criticisms of the DEIS are no longer relevant due to Entergy’s submission of the AEI 

Report and other current documents, which are based on more recent data and on detailed 

empirical analysis (as opposed to predictive models) of Hudson River data sets. 

Entergy’s AEI Report and other current documents cast doubt on the relevance 

and accuracy of ESSA’s criticisms concerning the method used to compare entrainment 

and impingement mitigation alternatives and the detailed population-level impact 

analyses for Atlantic tomcod, bay anchovy, striped bass, and white perch. The first 

reason that ESSA’s criticisms of the DEIS are no longer relevant is that a larger data set 

was available for the AEI Report as compared to the DEIS. The DEIS is based on data 

collected through 1997, whereas the AEI Report is based on data collected through 2004. 

This difference is important because some of the key conclusions in the DEIS, 

which were criticized by ESSA, relied on comparisons between population trends over 

the period 1991-1997 and similar trends over earlier time periods. The availability of 7 

additional post-1990 years allowed for more meaningful comparisons between recent and 

earlier time periods. The second reason that ESSA’s criticisms of the DEIS must be 

discounted is that the AEI Report was based on a fundamentally different approach to 

 

1

 This report supports the “Biological Effectiveness of Alternative Intake Technologies for Indian Point 

Units 2 and 3” (the “Biological Report”) prepared by Lawrence W. Barnthouse of LWB Environmental 

Services, Inc., Douglas G. Heimbuch of AKRF, Inc., Mark T. Mattson of Normandeau Associates, Inc., 

and John R. Young of ASA Analysis & Communication, Inc. 
2

evaluating the impacts of Indian Point’s cooling water withdrawals on Hudson River fish 

populations. Whereas the DEIS relied on predictive models to quantify impacts of 

cooling water withdrawals on future population trends, the AEI Report relied on 

empirical analyses of the 30-year time series of Hudson River data to test alternative 

hypotheses concerning causes of historical changes in fish populations. Critical 

assumptions required to implement the population models used in the DEIS, which were 

a major focus of ESSA’s review, were not used in the AEI Report. 

The following sections identify specific issues raised by ESSA that are now 

irrelevant, and also those issues that are still relevant. Additional quantitative analyses 

performed to address some of these issues are documented in Attachment D-1. 

D.1.1 ESSA Overview 

ESSA’s review included three major components: 

1. A review of the entrainment and impingement mitigation alternatives discussed in 

the DEIS, including the methods used to calculate Fish Protection Points (“FPP”), 

which were used in the DEIS to evaluate the influence of alternative outage 

schedules on entrainment mortality. 

2. Detailed evaluations of entrainment and impingement impact assessments for 

Atlantic tomcod, bay anchovy, striped bass, white perch, and American shad. A 

significant portion of the ESSA work for each species involved a detailed review 

of population models used in the DEIS. 

3. A review of the evaluation of cooling tower alternative presented in the DEIS.2

D.1.2 ESSA criticisms that are no longer relevant 

Density-dependence 

ESSA (2000) stated (p. iii) that “The basic logic of the DEIS rests heavily upon 

arguments that density-dependent mechanisms of compensatory survival offset the 

effects of generating station induced entrainment and impingement mortality.” In other 

words, ESSA challenges the DEIS’s conclusion that mortality caused by entrainment and 

impingement reduces competition for food between the young fish that are not entrained 

or impinged, leading to increased survival that offsets the plant-induced mortality. For 

this reason, a significant portion of ESSA’s work involved a detailed review of 

population dynamics models that were used in the DEIS to quantify density-dependence 

in Hudson River fish populations. With the exception of specific data-related 

 

2

 The technology alternatives addressed in the DEIS are superseded by the alternative technologies 

discussed in this report. Accordingly, ESSA’s comments on the DEIS cooling tower alternative are not 

relevant and need not be discussed here. 
3

uncertainties discussed below, however, ESSA’s comments on density-dependence and 

modeling are no longer relevant, because Entergy’s AEI Report did not rely on densitydependence, and did not use models of the type critiqued by ESSA. 

The Fish Protection Point (“FPP”) system 

In the DEIS, the amount of protection from entrainment that could be achieved by 

reducing cooling water flow is expressed as FPPs, which were used to compare the 

biological benefits of alternative unit outage schedules. FPPs are not used to quantify 

biological benefits associated with the alternative technologies analyzed in this report. 

Thus, most of ESSA’s comments concerning FPPs are not relevant. Both the FPP system 

and the AEI Report assessment approach, however, relied on entrainment and 

impingement estimates termed conditional mortality rates (“CMR”).3

 Hence, ESSA’s 

comments on the methods and data used to calculated CMRs are still relevant and are 

discussed below. 

Bay anchovy individual-based model 

ESSA commented on the use in the DEIS of an “individual-based population 

model” to quantify potential impacts of cooling water withdrawals on bay anchovy. The 

model in question was not used in the AEI Report, Thus, ESSA’s comments on the 

model are no longer relevant. 

Alternative American shad modeling 

As an addendum to ESSA’s (2000) report, Deriso et al. (2000a) used an 

alternative spawner-recruit model to quantify the combined impacts of cooling water 

withdrawals and fishing on American shad. According to the model results derived by 

Deriso et al. (2000a), entrainment and impingement at Hudson River power plants 

significantly affect the abundance and sustainable harvest of adult shad. 

Conclusions based on the analysis of Deriso et al. (2000a) are no longer relevant, 

for two reasons. First, a recent stock assessment performed by the Atlantic States Marine 

Fisheries Commission (ASMFC 2007) concluded a serious decline in the coastwide 

abundance of American shad has occurred since 1990, that the primary cause of the 

decline is increased mortality of adult fish (not the early life stages of fish that are 

susceptible to cooling water withdrawals), and that commercial fishing is the most likely 

cause of the increased mortality. The chapter on the Hudson River American shad 

population, which came to this same conclusion, was drafted by NYSDEC staff. 

Mortality to early life stages related to cooling water withdrawals was not identified as a 

significant contributing cause. 

 

3

 CMRs estimate the fraction by which the abundance of young-of-the-year fish is reduced due to 

entrainment or impingement [AEI Report, p. 13]. For entrainment, CMRs are a function of the spatial 

and temporal distributions of susceptible life stages within the river, the rates of cooling water 

withdrawals by power plants, and the mortality rates of entrained organisms 
4

Second, potential mortality of Hudson River American shad related to cooling 

water withdrawals has already been greatly reduced since the DEIS was completed. 

According to Table V-26 of the DEIS, the Albany Steam Plant was historically 

responsible for 85% of all entrainment and impingement mortality of American shad. 

This plant was permanently shut down in 2005. 

D.1.3 ESSA criticisms that are still relevant 

As discussed in more detail below, some of ESSA’s criticisms of the DEIS are 

relevant and, accordingly, must be addressed in turn. In total, ESSA focuses on five 

issues that are relevant to this SPDES proceeding. First, Section 2.5 of ESSA (2000) 

discusses issues related to entrainment estimation and the use of CMR estimates for the 

years 1991-1997 as the basis for calculating FPPs. Because CMRs were also used in 

Entergy’s AEI Report as metrics for entrainment impacts, these comments are potentially 

relevant to the AEI Report and other related documents. ESSA expressed “substantial 

concerns” about the influence on FFP calculations of inter-annual variation and 

uncertainties in through-plant survival rates. 

Second, Section 3 of ESSA’s report discusses issues relating to the assessment of 

impacts of entrainment and impingement on Atlantic tomcod. Some of these issues 

involved assumptions concerning density-dependence and carrying capacity used in 

modeling tomcod population dynamics. As noted above, these issues are no longer 

relevant because the AEI Report did not rely on density-dependence and did not use 

models of the type critiqued by ESSA. However, ESSA also raised concerns regarding 

uncertainty in data sources, the magnitude of fishing pressure, temperature effects, and 

effects of changes in flow and nutrients. These issues are addressed below. 

Third, Section 4 of ESSA’s report discusses issues relating to the assessment of 

impacts on bay anchovy. Most of these issues concern the bay anchovy individual-based 

model used in the DEIS. These bay anchovy-related criticisms are not relevant because 

this individual-based model was not used in the AEI Report. However, ESSA also 

commented on analyses of impacts of predation on bay anchovy provided in the DEIS, 

and on ecological factors contributing to variations in bay anchovy abundance. These 

issues are still relevant, and are addressed below. 

Fourth, Section 5 of ESSA’s report discusses issues relating to the assessment of 

impacts on striped bass. In addition to criticisms related to population modeling that are 

no longer relevant because the AEI Report did not rely on models of the kind used in the 

DEIS, ESSA expressed concerns about the reliability of the striped bass abundance 

indices used in the DEIS. This issue is still relevant and is addressed below. 

Fifth, and finally, Section 6 of ESSA’s report discusses issues relating to the 

assessment of impacts on white perch. Some of these issues relate to analyses of densitydependence that are no longer relevant because the AEI Report did not rely on densitydependence. ESSA, however, also criticized the DEIS’s analyses of temporal variation in 
5

white perch abundance, and of alternative hypotheses concerning causes of this variation. 

In addition, ESSA recommended the use of “production foregone” modeling to quantify 

ecosystem-level effects of entrainment and impingement. These issues are relevant and 

are discussed below. 

D.1.4 Detailed evaluation of relevant issues 

Uncertainty in estimating CMRs 

CMRs were a key component of the FPP system used in the DEIS and the 

hypothesis-testing approach used in Entergy’s AEI Report. In both of these applications, 

CMRs were used as measures of entrainment and impingement mortality. As discussed in 

Section 2.3 of the AEI Report, CMRs should not be used as measures of the impacts of 

entrainment and impingement mortality on the long-term abundance or sustainability of 

susceptible fish populations. 

ESSA criticized the DEIS’s use of through-plant survival rates in the CMR 

estimates, and also expressed concern that changes in the riverwide distribution of 

entrainable life stages during the period 1991-1997 might invalidate the use of CMRs as 

measures of plant-related mortality rates during this period. 

With regard to through-plant mortality rates, ESSA (2000) notes that the DEIS 

used mechanical mortality rates averaged over all plants for which data were available, 

and that inadequate data for estimating mechanical mortality rates was available for some 

species. Because of these data limitations, ESSA (2000) concludes that the through-plant 

mortality rates used in the DEIS were “lower bounds” on actual entrainment mortality. 

This criticism does not apply to assessments performed for Unit 2 and Unit 3, because 

through-plant mortality rates for fish species entrained at these Units are based solely on 

data collected at Unit 2 and Unit 3, so that no averaging across plants is needed. Where 

data were inadequate to estimate a through-plant survival rate, zero survival was 

conservatively assumed. 

With regard to inter-annual variation in entrainment, ESSA (2000) presents a 

table (Table 4, p. 13) and several figures (Figures 1a through 1e) showing an apparent 

decline in CMR values during the period from 1991-1997 used for the FPP baseline. In 

section 2.5.2, ESSA (2000) argues that these apparent declines could indicate a shift in 

the distribution of entrainable life stages of fish in response to altered habitat conditions. 

The annual CMR values are based on year-specific survey data that track the 

longitudinal, i.e. upstream or downstream, distribution of fish within the river. Thus, the 

CMR estimates only account for upstream or downstream movements. The models used 

to calculate CMRs do not, however, utilize year-specific estimates of the lateral 

distribution of fish in the vicinity of each facility, including Units 2 and 3. Instead, the 

models use to calculate CMRs use a plant-specific distribution factor derived from data 

collected over several years in the 1980s to estimate the density of entrained organisms in 

cooling water withdrawn by each facility, relative to the average density of organisms in 
6

the river cross-section adjacent to the intake structure. ESSA (2000) suggested that if the 

habitat changes that lead to alterations in the upstream-downstream distribution of 

entrainable organisms also led to a movement of organisms toward the shoreline where 

they would be more vulnerable to entrainment, then recent CMRs and FPP values would 

be biased and would underestimate the actual entrainment mortality imposed by cooling 

water withdrawals. Because the most recent years (i.e., 1991-1997) were the basis for 

evaluating the alternative outage schedules addressed in the DEIS, the level of fish 

protection provided by all of the alternatives would be overestimated. 

Entergy’s AEI Report evaluated both time trends in CMRs and trends in upstream 

vs. downstream distribution of Representative Important Species (“RIS”) using a larger 

data set than was available for the DEIS. A statistically significant shift in upstream 

versus downstream distribution of larvae over the period 1984-2004 was observed for 

only one species, spottail shiner. Statistically significant long-term trends in CMR values 

for Unit 2 and Unit 3 were not observed for any species. Hence, the analysis documented 

in the AEI Report, which included 7 additional years of data, showed that the arguments 

used by ESSA to support its conjecture about biased CMR values are not supported by 

available data. Contrary to ESSA’s assertions, the spatial distributions of the species 

most susceptible to entrainment at Indian Point have not changed, and the estimated 

CMR values show no long-term trend. No empirical evidence supports ESSA’s 

speculation that larval fish might have moved toward the shoreline in recent years, 

resulting in increased susceptibility to entrainment and biased CMR values. 

Additional evidence supporting the validity of the CMR as a measure of annual 

variations in mortality at Unit 2 and Unit 3 is provided in Attachment D-1. Attachment 

D-1 documents an analysis of the relationship between CMR estimates for Unit 2 and Unit 

3 and a simple, empirical predictor of entrainment risk based on (1) larval location in the 

river and (2) cooling water withdrawal rates at IP and IP3. The empirical predictor does not 

include the distribution factors and survival estimates that were criticized by ESSA. If 

ESSA’s claims concerning uncertainties and biases in the CMRs had merit, then the CMR 

values should be weakly correlated with independent measures of entrainment susceptibility 

and the nature of the relationship should be different during years after 1990 than during the 

period from 1974-1990. Attachment D-1 shows that, for all of the species addressed in 

ESSA’s comments (Atlantic tomcod, American shad, bay anchovy, river herring, striped 

bass, and white perch), CMR values are strongly correlated with independent measures of 

larval location and cooling water withdrawal rates. Moreover, none of these relationships are 

different during the years after 1990 than during the years 1974-1990. Furthermore, 

Attachment D-1 shows that the available data support the conclusion that a systematic shift in 

nearshore-offshore distributions patterns of larvae did not occur between the 1980’s and 

1990’s, as hypothesized by ESSA. Hence, ESSA’s concern that recent CMR rates would be 

biased and would underestimate the actual entrainment mortality imposed by cooling 

water withdrawals is invalid.

Uncertainties in the Atlantic tomcod assessment 

ESSA’s comments on the Atlantic tomcod assessment were summarized in 

Section 3 of the review report and documented in a companion report (Parnell et al. 
7

2000). These comments addressed four issues that are relevant to the AEI Report and 

other reports related to this SPDES proceeding: uncertainty in data sources, the 

magnitude of fishing pressure, temperature effects, and effects of changes in flow and 

nutrients. 

At the outset, Entergy has resolved ESSA’s concerns regarding data uncertainty. 

ESSA noted unresolvable discrepancies between the data presented in Appendix VI-4-B 

and Table 9 of Appendix V-3-C of the DEIS. In preparing the AEI Report, Entergy 

performed a complete review of all data sources and fully documented all data used in 

Appendix B to that report. The tables referred to in ESSA’s comments were not used in 

the AEI Report. Therefore, the discrepancies noted by ESSA do not affect any analyses 

that are relevant to the current proceeding. 

ESSA claimed that the data used in Atlantic tomcod population modeling was of 

“poor quality” because estimates of annual egg production were derived from spawner 

abundance data, sex ratios, age structure, and age-specific fecundity. According to 

ESSA, this approach leads to “confounding.” In fact, estimates of spawner abundance, 

sex ratio, age structure, and age-specific fecundity are commonly used to estimate egg 

production, when estimates of the necessary parameters are available. Deriso et al. 

(2000a) used these same parameters as inputs to their spawner-recruit model for 

American shad. Models that utilize these kinds of data are termed “age-structured” 

models, and are discussed in Chapter 6 of Quinn and Deriso (1999). The Atlantic tomcod 

mark-recapture program provides annual estimates of all of the parameters needed to 

calculate egg production. ESSA did not review or criticize the methods used in this 

mark-recapture program. In sum, ESSA’s claim that the data derived from this survey are 

“poor quality” is groundless. 

ESSA claimed that the time series of abundance data used in the Atlantic tomcod 

analysis was too short, because data were available only through 1997. As noted above, 

the AEI Report conclusions are based on an additional 7 years of data. The critical 

period of concern for Atlantic tomcod, both in the DEIS and in the AEI Report, began in 

1991. Thus, the additional 7 years of data is critical, as the AEI Report’s time series of 

available data for the post-1990 period is twice as long (1991-2004) than the DEIS data 

(1991-1997). Thus, the AEI Report addressed ESSA’s concern regarding data 

availability. 

ESSA claimed that the DEIS should have evaluated the importance of fishing 

mortality as an influence on Atlantic tomcod population dynamics. The AEI Report also 

could not address this impact as there is no data are available concerning the magnitude 

of fishing mortality for Atlantic tomcod. In the absence of data, fishing mortality could 

not be included in the list of potential causes of change evaluated in the AEI Report. 

ESSA noted that the DEIS did not address effects of temperature on Atlantic 

tomcod. The AEI Report addresses relationships between long-term trends in river 

temperature and Atlantic tomcod abundance. It concludes that elevated summer 

temperatures are associated with reduced survival of juvenile Atlantic tomcod, however, 
8

long-term trends in river temperature cannot account the decline in tomcod abundance 

that has occurred since 1990. The AEI report concludes that other factors, probably 

including predation by striped bass, were responsible for this decline. 

ESSA noted that the DEIS did not address effects of changes in river flow and 

nutrients on the growth and survival of juvenile Atlantic tomcod. ESSA provided no 

hypothesis concerning how flow itself could affect Atlantic tomcod growth or survival. 

In the absence of a plausible causal hypothesis, the inclusion of flow in the suite of 

causes addressed in the AEI Report would have been meaningless. Changes in nutrient 

concentrations could conceivably lead to changes in the growth or survival of many 

species, however, no long-term, riverwide data on nutrient concentrations are available 

for the Hudson River. Hence, this parameter could not be included in the trends analyses 

performed for the AEI Report. 

Uncertainties in the bay anchovy assessment 

ESSA’s comments on the bay anchovy assessment were summarized in Section 4 

of the review report and documented in a companion report (Parnell and Marmorek 

2000). The bulk of the review focused on the results of bay anchovy population 

modeling. Since no population model was included in the AEI Report, most of ESSA’s 

comments are no longer relevant. Three issues raised by ESSA are still relevant, 

however: (1) the importance of immigration from New York Harbor in maintaining the 

bay anchovy population present in the Hudson River estuary; (2) the importance of 

predation as a factor influencing bay anchovy abundance; and (3) the potential influence 

of entrainment on the biomass of bay anchovy available to predators. 

These issues have been addressed in published scientific studies and in additional 

new analyses documented in Attachment D-1. As discussed in the DEIS (pp. V-112 to 

V-114), bay anchovy is a marine species that is abundant in coastal waters and estuaries 

along the Atlantic and Gulf coasts, between Maine and the Yucatan Peninsula, Mexico. 

During summer, bay anchovies are abundant in the Hudson River and in adjacent marine 

waters. However, during winter they migrate south and are virtually absent from the 

New York region. This simple fact of life history demonstrates that the Atlantic coastal 

population is the ultimate source of all bay anchovies present in the Hudson River. 

Dunning et al. (2006a) documented the presence of bay anchovy eggs and larvae in New 

York Harbor, the East River, and Long Island Sound. They found that the peak 

abundance of bay anchovy eggs and larvae in these water bodies was about eight times 

higher than in the Hudson River. That finding clearly demonstrates that a large source 

population is available in waters adjacent to the Hudson. Dunning et al. (2006a) also 

found that bay anchovy eggs were present only in the lower estuary, adjacent to New 

York Harbor. 

The likely nature of movements between coastal waters and the Hudson River is 

examined further in Attachment D-1. The purpose of this analysis is to determine 

whether bay anchovy larval abundance in the Hudson River can be predicted by salinity, 

freshwater flow rate and water temperature. Literature discussed in the DEIS shows that 
9

bay anchovy spawn primarily in waters with salinities greater than 10 parts per thousand 

(“ppt”), or about one-third the salinity of seawater (33 ppt). The salinity of the Hudson 

River estuary is determined by the degree of mixing between marine waters transported 

into the Hudson by tidal movements and fresh water transported downstream from the 

Hudson River watershed. Salinities are highest at the lower end of the estuary and 

gradually decrease upstream. When freshwater flows are high, less marine water is 

transported into the Hudson, the salinity of the lower Hudson decreases, and the 

proportion of the river within which salinities are suitable for bay anchovy spawning 

decreases. When freshwater flows are low, more marine water is transported into the 

Hudson, the salinity of the lower Hudson increases, and the proportion of the river within 

which salinities are suitable for bay anchovy spawning increases. 

If bay anchovy in the Hudson River are only a small fraction of the mid-Atlantic 

stock, and if they enter the Hudson River opportunistically depending on the movement 

of saline waters from New York Harbor into the Hudson, then larval abundance should 

be correlated with physical properties of the Hudson. When a large proportion of the 

river is influenced by the intrusion of saline marine waters, more bay anchovy should 

move into the river to spawn, and more larvae should be present than in years when a low 

proportion of the river is influenced by marine intrusion. 

The analysis presented in Attachment D-1 examines the relationship between the 

bay anchovy larval abundance index used in the AEI Rreport and the proportion of the 

Hudson River with salinity greater than 5 parts per thousand (“ppt”) during the spring, 

freshwater flow rates in the spring, and the proportion of the river with high temperatures 

(>75o

 F) in the spring. As documented in Attachment D-1, a strong relationship exists 

between the abundance of bay anchovy larvae in the Hudson and these physical 

properties of the River. Since the abundance of larvae is an indicator of the abundance of 

the spawning adults that produced the larvae, these results indicate that more bay 

anchovy move into the river to spawn when salinities are high than when salinities are 

low. Together with the immigration findings of Dunning et.al. (2006a), the analysis 

documented in Attachment D-1 supports the proposition that the bay anchovy population 

present in the Hudson River is a component of a much larger coastal population, of which 

a variable fraction enters the river opportunistically depending on annual salinity 

conditions. 

With respect to predation, although the AEI Report concluded that entrainment at 

Unit 2 and Unit 3 was not an important influence on the survival of bay anchovy larvae to 

the juvenile stage, it did not include a quantitative analysis of potential predation effects. 

Attachment D-1 documents an analysis that addresses the influences of both entrainment 

and striped bass predation on the survival of bay anchovy larvae in the Hudson River. 

The first step in this analysis shows that the abundance of juvenile bay anchovy in the 

Hudson is strongly influenced by the spatial distribution of larvae. When larvae are 

widely distributed, juvenile bay anchovy are more abundant than in years when larvae are 

restricted to the lower river. The second step in the analysis shows that, in contrast to the 

influence of spatial distribution, entrainment, as measured using the same CMR values 

used in the AEI Report, has no detectable influence on the abundance of juvenile bay 
10

anchovy. The third step in the analysis shows that potential striped bass predation, as 

measured using a striped bass abundance index, has a statistically significant influence on 

the abundance of juvenile bay anchovy. This result supports the conclusion of the AEI 

Report that entrainment at Unit 2 and Unit 3 has no influence on the abundance of bay 

anchovy in the Hudson River, but that predation by striped bass may be an important 

influence on this population. 

ESSA asserted that, even if immigration from outside the Hudson River replaced 

bay anchovy lost due to entrainment and impingement, immigration would not 

compensate for the potential ecological impacts of entrainment on coastwide bay 

anchovy abundance. ESSA recommended that a “production foregone” analysis be 

performed to address the potential impacts on predators due to reduced coastwide 

abundance of bay anchovy. Production foregone refers to the loss in potential future prey 

biomass that occurs because the entrained and impinged prey are no longer feeding and 

growing. Because the potential prey biomass is reduced, prey consumption by predators 

is also reduced, resulting in a reduction in predator biomass. Estimates of production 

foregone due to bay anchovy entrainment are provided in Attachment D-1. Such 

estimates are used in economic benefits analyses to quantify the potential reduction in 

harvest of predator fish resulting from reduced abundance of prey (EPA 2004, EPRI 

2004). As discussed in section D.2 below, production foregone models utilize 

unreastically conservative assumptions about the fate of entrained and impinged fish and, 

therefore, overestimate the actual reductions in predator biomass and harvest that would 

result from entrainment and impingement of prey such as bay anchovy. 

Uncertainties in the striped bass assessment 

ESSA’s comments on the striped bass assessment were summarized in Section 5 

of the review report and documented in a companion report (Deriso et al 2000b). Most of 

the comments related to the striped bass population model used in the DEIS, and are no 

longer relevant because the AEI Report did not rely on a population dynamics model. 

However, ESSA also criticized the juvenile abundance indices, including the Beach Seine 

Survey (“BSS”) index, used as inputs to the striped bass population model. According to 

ESSA, these indices are unreliable measures of the annual production of young striped 

bass from the Hudson River. Because the AEI Report relied on the BSS index, this 

criticism is still relevant and is addressed below. 

Barnthouse et al. (2003) showed that the striped bass BSS index is strongly 

correlated with the NYSDEC juvenile striped bass index, and that both of these indices 

are strongly correlated with measures of subsequent 1-year-old and 2-year-old striped 

bass abundance derived from the annual striped bass mark-recapture survey. This finding 

supports the validity of the BSS index. Similar analyses documented in Appendix A to 

the AEI Report also supported the validity of the BSS index. The fact the Atlantic States 

Marine Fisheries Commission accepts the NYSDEC index, which is strongly correlated 

with the BSS index, as a valid measure of striped bass recruitment from the Hudson 

River, further supports the validity of the BSS index. This support for the BSS index 

mitigates against ESSA’s concern about the validity of the index. 
11

Moreover, ESSA’s critique of the BSS and NYSDEC juvenile abundance indices 

was based on an assertion that the rate of migration of juvenile striped bass out of the 

Hudson has changed since 1988 as a result of improvements in water quality in the lower 

Hudson. According to ESSA, since 1988 juvenile striped bass have been emigrating to 

the Long Island Sound during the late summer and fall period in which both the 

generators and NYSDEC are conducting their surveys. ESSA supported this assertion 

with data showing an increase in the abundance of juvenile striped bass in the western 

Long Island Sound in recent years. If the fraction of juvenile striped bass emigrating 

from the Hudson into Long Island Sound during the late summer and fall has increased, 

then index results for recent years would be biased because the surveys are sampling a 

smaller proportion of the habitat occupied by juvenile striped bas than they were in 

earlier years. This bias, according to ESSA, would affect both the BSS and the NYSDEC 

indices. 

After ESSA’s review of the DEIS, Dunning et.al. (2006b) documented the 

presence of striped bass larvae in the East River, and demonstrated that striped bass 

larvae from the lower Hudson River could be passively transported, by tidal currents, to 

the East River and western Long Island Sound. Hence, the juvenile striped bass present 

in Long Island Sound during the late summer and fall could have been passively 

transported out of the Hudson as larvae, rather than emigrating as juveniles. 

Accordingly, Attachment D-1 contains an analysis of the source of the juvenile 

striped bass present in western Long Island Sound. The analysis uses two variables to 

explain patterns of juvenile abundance in Western Long Island Sound. The first is the 

abundance of striped bass larvae in the Hudson River, and the second is freshwater flow 

in June. This analysis shows that striped bass juvenile abundance in Western Long Island 

Sound is proportional to larval abundance in the Hudson River; and that the 

proportionality depends on the freshwater flow rate in June. Higher freshwater flow rates 

are associated with higher proportions of the larval abundance leaving the River. There 

is no indication that this relationship changed after 1988. Thus, ESSA’s concern that 

both the BSS and NYSDEC indices are biased is unfounded. 

The results from this analysis indicate that the recent increase in abundance of 

juvenile striped bass in western Long Island Sound has been due to a combination of 

increased larval abundance in the Hudson River and inter-annual variability in freshwater 

flow rates. These results, together with the previous findings discussed above, strongly 

support the validity of the BSS index as a measure of long-term trends in the abundance 

of juvenile striped bass in the Hudson River. 

Uncertainties in the white perch assessment 

ESSA’s comments on the white perch assessment were summarized in Section 6 

of the review report and documented in a companion report (Parnell and Marmorek 

2000). ESSA criticized the method used in the DEIS to explore temporal variations in 

white perch abundance, and to evaluate alternative hypotheses that could explain those 
12

variations. In addition, ESSA criticized the indices of density-independent survival of 

larvae white perch. Finally, ESSA recommended the use of an index of “biomass loss to 

the ecosystem” to address the impact of white perch entrainment both on the white perch 

population and on the Hudson River ecosystem. 

In the DEIS, temporal variations in abundance of white perch life stages were 

addressed by subdividing the available time series (1974-1997) in terms of three time 

periods: 1974-1979, 1980-1988, and 1989-1997. ESSA argued that this subdivision is 

subjective, and that an alternative subdivision could lead to different conclusions 

concerning the nature of the trends. This comment is no longer relevant, because the 

white perch analysis in the AEI Report did not subdivide the available time series (1974-

2004) into segments. 

In the DEIS, five alternative hypotheses concerning causes of changes in the 

abundance of white perch were evaluated: fishing, entrainment, water quality, 

competition with striped bass, and predation by striped bass. ESSA argued that the 

evaluations in the DEIS relied on subjective visual evaluation of patterns and correlations 

between indices. For this reason, ESSA concluded that the evaluations did not provide 

information useful for forecasting the effect of power plant water withdrawal on the 

Hudson River white perch population. This comment is still relevant, because 

hypothesis-testing is a key component of the AEI Report. 

The approach taken to hypothesis-testing in the AEI Report was, however, quite 

different from the approach taken in the DEIS. The AEI Report relied on the 

“ecoepidemiology” approach documented by Suter (2007). This approach involves the 

comparative testing of relevant hypotheses against five criteria for evaluating causal 

associations. The five criteria and the steps involved in applying the criteria were 

described in Section 3 of the AEI Report. Consistent with Suter et al. (2007), the intent 

was not to definitively identify the causes of changes in the abundance of white perch and 

other fish populations, but to distinguish between causal agents that possibly could have 

contributed to the observed changes and agents that are very unlikely to have contributed 

to those changes. For white perch, as for the other species addressed in the AEI Report, 

entrainment at Unit 2 and Unit 3 was found to be a very unlikely to have contributed to 

historical abundance trends. No attempt was made to forecast future trends in abundance 

of any species. However, the implication of the analysis documented in the AEI Report 

is that, since entrainment at Unit 2 and Unit 3 is unlikely to have influenced historical 

abundance trends in white perch or other species, it is similarly unlikely to influence 

future trends. 

ESSA criticized the DEIS for using the post yolk-sac larval (“PYSL”) abundance 

index as an index of density-independent survival of PYSL. This comment is irrelevant, 

because the PYSL index was not used in this way in the AEI Report. In the AEI Report, 

the PYSL index was used strictly as an abundance index. The survival of white perch 

PYSL was addressed by comparing the PYSL index to the white perch juvenile index 

from the Beach Seine Survey. This survival index would include the effects of both 

density-dependent and density-independent survival. Thus, ESSA’s concern is no longer 

relevant. 
13

ESSA recommended that the DEIS should be revised to address “biomass lost to 

the ecosystem,” i.e., the loss of food available to predators due to the entrainment and 

impingement of white perch. These losses would include the biomass of fish killed by 

entrainment and impingement, the loss of biomass due to the future growth of the 

entrained and impinged fish, and the loss of biomass harvest by fisheries due to 

entrainment and impingement mortality. According to ESSA, such an assessment should 

make the conservative assumption that all mortality represents a food source no longer 

available to predators. In other words, the entrained and impinged fish are completely 

removed from the ecosystem, predators that would have consumed those fish do not find 

alternative prey, and prey that would have been consumed by those fish are not consumed 

by other predators. 

The fallacy of ESSA’s preferred conservative assumption is discussed in depth in 

Section D.2 of this attachment. All fish entrained or impinged at Unit 2 and Unit 3 are 

returned to the river, where they are susceptible to consumption by the same suite of 

predators that would have consumed them had they not been entrained or impinged. 

Because of the many interconnecting links in typical estuarine food webs, little or no 

biomass would actually be lost to the ecosystem. 

D.1.5 Conclusion 

 Comments made in ESSA’s (2000) review of the DEIS do not affect the 

reliability of Entergy’s AEI Report, the analysis of alternative technologies documented 

in this report, or any other report submitted by Entergy in this Proceeding. An in-depth 

analysis of ESSA’s review shows that all of ESSA’s substantive comments are either 

irrelevant as to the AEI Report and other documents, or are easily refuted by additional 

analyses of the available Hudson River data and published scientific literature. 

D.2 Impacts on the Hudson River ecosystem 

The FEIS incorrectly concludes that power plants have appreciable indirect 

effects on fish populations in the Hudson River. (FEIS at 51-45). Quoting from a report 

prepared by Henderson and Seaby (2000), the FEIS states that “Large temporal changes 

in fish species abundance together with a small decrease in total species richness and 

diversity suggest that the Hudson estuary ecosystem is far from equilibrium” (FEIS, p. 

52) and “it is not possible to dismiss the influence of the power plants on the fish 

community, particularly when it is proposed to further increase fishing mortality rates.” 

In later paragraphs, the FEIS argues that: 

 Mortality related to cooling water withdrawals is not comparable to fishing mortality. 

 Mortality related to cooling water withdrawals is comparable to habitat degradation. 
14

 Mortality related to cooling water withdrawals decreases the forage base for Hudson 

River fish species and short-circuits the trophic pyramid. 

 Mortality of small organisms related to cooling water withdrawals could contribute to 

the development of harmful algal blooms. 

 Mortality related to cooling water withdrawals directly reduces the quantity of 

organisms within the water column over significant stretches of the river. 

All of these arguments conflict with well-documented scientific facts concerning 

the Hudson River estuary and coastal/marine ecosystems in general. The following 

subsections specifically address each of the arguments raised in the FEIS. 

D.2.1 Comparison of cooling water withdrawals to fishing mortality 

Mortality due to commercial and recreational fishing has a greater impact on 

Hudson River fish populations than cooling water withdrawals from the Stations. The 

FEIS agrees, but mischaracterizes the actual effects of fishing mortality. The FEIS 

correctly notes that “aquatic resource mortality from power plants is not comparable to 

the ‘selective cropping’ that occurs in a regulated fishing or hunting season”(FEIS, p. 53). 

The FEIS goes on, however, to incorrectly portray the effects of fishing and particularly 

overfishing on fish populations: “only selected species are harvested, and the forage base 

remains intact or is improved because fewer individuals higher on the food chain are 

available to consume lower food chain organisms. Furthermore, fishing and hunting 

seasons are generally established during that part of the annual cycle which provides both 

maximum benefit to the users and ensures the sustainability of the population. Mortality 

at these Hudson River power plants is not limited to a specific, benign season; it occurs 

throughout the annual cycle, whenever the plants operate their ‘once-through pumps’.” 

(p. 53). 

 

The FEIS’s benign view of harvesting stands in stark contrast to the conclusions 

concerning ecological effects of fishing expressed in the report of the Pew Oceans 

Commission (2003), prepared by a blue-ribbon panel that included then-New York 

Governor George Pataki. Pages 38-41 of this report summarize both the catastrophic 

effects of overfishing on marine ecosystems, and the management failures that lead to 

overfishing. Worldwide, populations of large-bodied top carnivore species such as tuna, 

swordfish, salmon, and many sharks, have been drastically depleted by harvesting. As 

the populations of these species decline, fishermen shift their attention to smaller species, 

eventually depleting these species as well. The consequences of this process, termed 

“fishing down the food web,” are described in the following way by the Pew Oceans 

Commission: 

“The consequences of this disruption can be severe. Diversified food webs with 

sufficient population sizes at all trophic levels allow predators to switch among prey as 

the abundance and mix of species in a system naturally fluctuates. Overfishing of top-
15

trophic species and subsequently mid- and low-trophic species removes this natural 

benefit of biodiversity by gradually disrupting and truncating trophic relationships. This 

leads to unpredictable changes, such as increased disease outbreaks and the proliferation 

of previously suppressed pests and weedy species.” 

This conclusion is supported by a report prepared for the Pew Oceans 

Commission by Dayton et al. (2002), which provides a comprehensive review of the 

ecological effects of fishing. Other adverse effects of fishing discussed by the 

Commission and by Dayton et al. (2002) include the physical effects of gears such as 

bottom trawls and dredges, and the bycatch of unwanted fish captured by fishermen who 

are targeting other species. 

The Pew Commission’s conclusions concerning the often catastrophic effects of 

poor fishery management practices are also supported by other published literature. 

Myers and Worm (2003) recently found that harvesting has reduced the worldwide 

biomass of large, predatory fish by 90% from the levels that were present prior to the 

introduction of modern fishing technologies. These predators play an important role both 

in controlling the abundance of other species and in controlling the pathways through 

which energy and biomass move through marine food webs (Steele and Schumacher 

2000, Jackson et al. 2001, Daskalov 2002). Reducing the abundance of large predators 

leads to increased abundance of forage fish and pelagic invertebrates (e.g., jellyfish), 

decreased abundance of zooplankton, and increased abundance of phytoplankton and 

suspended organic matter (Steele and Schumacher 2000). 

The Pew Commission also discussed the fishery characteristics and management 

failures that have repeatedly led to overfishing, in spite of the best intentions of 

management agencies. Key fishery characteristics that encourage overfishing include 

excess capacity of fishing fleets and the availability of new technologies that greatly 

increases the ability of fishermen to locate schools of fish and exploit previously 

inaccessible areas. Key management failures include the single-species approach to 

harvest regulation, an emphasis on short-term commodity production, and the influence 

of commercial fishing interests on management decisions. The Commission 

recommended a variety of changes in fishery management policies to address these 

concerns. 

With respect to the problems discussed in the Pew Commission report and other 

authoritative sources, cooling water withdrawals are far less destructive than fishing. 

Cooling water withdrawals entrain and impinge organisms only from the immediate 

vicinity of intake structures, and only when pumps are operating. They do not target 

specific species such as large predators, do not actively seek out schools of fish, and do 

not physically alter the habitat from which cooling water is withdrawn. Entergy’s AEI 

Report documents a comparison between fishing mortality and mortality due to 

entrainment at Units 2 and 3 for two harvested RIS species: striped bass and American 

shad. For both species, entrainment mortality is negligibly small compared to fishing 

mortality. 
16

In short, the FEIS is correct in stating that cooling water withdrawals are not 

comparable to harvesting, but incorrect in characterizing its effects as somehow benign. 

D.2.2 Comparison of cooling water withdrawals to habitat 

degradation 

 The FEIS (p. 35) states that “Rather than ‘selective cropping,’ the impacts 

associated with power plants are more comparable to habitat degradation; the entire 

natural community is impacted.” This statement mischaracterizes the true nature of 

habitat degradation as compared to cooling water withdrawals. 

Habitat degradation resulting from the rapid urbanization of coastal environments 

was identified the Pew Commission (2003) as a primary threat to ecologically and 

economically important species as well as to rare and unique habitats (p. 51). 

Urbanization directly destroys habitats such as forests and wetlands, reducing the value 

of these habitats to support fish and wildlife, control runoff, and provide natural pollution 

control. Increased runoff from the transformation of vegetated surfaces to impervious 

surfaces such as roads and parking lots causes increased flooding and pollutant loading. 

Polluted runoff was identified by the Pew Commission (p. 56) as “probably the most 

harmful impact of development on marine and freshwater ecosystems.” As shown in the 

figure on p. 50 of the Pew Commission report, in 1930 the development “footprint” of the 

New York metropolitan area covered only a small region of the Hudson Valley 

immediately surrounding New York City. By 1990, the entire valley between the Battery 

and the Hudson Highlands had been affected by urban and suburban development. 

In addition to degradation related to urban sprawl, the Hudson River has been 

affected by damming, dredging, and filling ever since the arrival of European settlers. 

As discussed by Miller et al. (2006), the northern third of the Hudson River estuary has 

been substantially modified since the late 18th century by dredge and fill activities 

associated with navigational channel maintenance. Wetlands and natural shoreline that 

formerly fringed the Hudson have also been dredged and filled to support railroad 

construction. According to Squires (1992), 54% of the eastern shore of the Hudson and 

63% of the western shore are lined by railroads immediately adjacent to the river and 

largely constructed from fill. These activities have caused significant losses of intertidal 

and shallow-water areas that serve as important nursery habitats for fish. In addition, 

approximately half of the tributaries to the estuary have dams or other anthropogenic 

obstructions on or near their mouths, restricting the spawning habitat available to 

migratory species such as river herring (Schmidt and Cooper 1996). 

Although dams may be removed to facilitate fish migration, the other changes 

discussed above are permanent and irreversible. As noted by Daniels et al. (2005), they 

have affected the composition of the Hudson River fish community in ways that are 

difficult to quantify because significant physical modifications of the Hudson predate 

reliable biological studies of the river. 
17

Cooling water withdrawals, in contrast, affect only the organisms present in the 

water column within the withdrawal zone of the intake structure, and only when pumps 

are operating. Cooling water withdrawals do not permanently alter the river channel, 

shoreline, or any other physical characteristic of the Hudson River. They do not affect 

rates of runoff or introduce pollutants into the river. Clearly, cooling water withdrawals 

cannot legitimately be compared to habitat degradation of the kinds highlighted by the 

Pew Oceans Commission and the other sources cited above. 

D.2.3 Impacts of cooling water withdrawals on ecological function 

 The FEIS incorrectly concludes that there are a variety of purported adverse 

effects of cooling water withdrawals on the ecological functions that would have been 

provided by entrained or impinged organisms. As discussed in greater detail below, the 

FEIS improperly makes this conclusion based on the outdated concept of a “trophic 

pyramid,” or the idea that organisms within aquatic ecosystems may be grouped into 

relatively discrete “trophic levels.” The FEIS states (p. 53) that the abundance of 

plankton (including microscopic plants and animals, as well as fish eggs and larvae) is 

reduced, thereby reducing the availability of food for organisms that are not entrained or 

impinged. In addition to depriving larger organisms of food, the loss of these small 

organisms may, according to the FEIS (p. 54), contribute to the development of harmful 

algal blooms (see section 3.4). The FEIS (p. 54) also claims that losses of small fish 

“short-circuits” the trophic pyramid and compromises the health of the natural 

community because the entrained or impinged fish are no longer able to perform their 

normal ecological functions. For example, rather than serving as food for a valuable fish 

such as striped bass or a bird, a bay anchovy entrained by a power plant cooling system 

and killed would be useful only as food for lower trophic level organisms. It would no 

longer be able to feed, concentrate nutrients into its tissues, or distribute its “manure” 

(i.e., waste products) for use by other organisms. The loss of millions of anchovies 

would, presumably, result in a significant reduction in the abundance food available 

predators, and also a decrease in the amount of plankton concentrated, concentrated, 

processed, and redistributed as waste products throughout the estuary. 

These claims made in the FEIS conflict with scientific facts concerning the nature 

of estuarine food webs, the ecology of specific fish species inhabiting the Hudson River, 

and the key aspects of cooling system operations at the Stations. The idea that organisms 

within aquatic ecosystems may be grouped into relatively discrete “trophic levels” as 

primary producers (plants that fix carbon using sunlight as an energy source), primary 

consumers (animals that eat plants), secondary consumers (animals that eat primary 

consumers) and so on at higher and higher levels was first formalized by Lindeman 

(1942). According to this theory, organisms at each level feed primarily on organisms at 

the next lower level. Animals that die before they are consumed are consumed by 

scavengers that feed primarily on dead organisms, or are degraded by decomposer 

organisms, primarily bacteria and fungi. Decomposition releases dissolved nutrients that 

can be used again by the primary producers at the bottom of the pyramid. 
18

Figure 1a depicts the cyclical flow of biomass in the Hudson River ecosystem, 

consistent with this view. Microscopic plants called “phytoplankton” withdraw nutrients 

from the water to support their growth. The phytoplankton are consumed by microscopic 

invertebrates called “zooplankton” that are, in turn, consumed by small fish such as bay 

anchovy. These smaller fish are then consumed by predatory fish like striped bass. 

Plants and animals that die from causes other than consumption by larger animals fall to 

the bottom of the estuary, where they may be consumed by scavengers (e.g., crabs, sand 

shrimp, and bottom-feeding fish). Ultimately, their tissues are broken down by bacteria 

and fungi. The nutrients released by decomposition are then available for uptake by 

phytoplankton. Figure 1b depicts the influence of entrainment on the Hudson River 

ecosystem, according to the FEIS (p. 54). Entrainment “short-circuits” the trophic 

pyramid by killing small fish, which then return directly to the scavenger/decomposer 

pool rather than being consumed by predators. Predator consumption (and subsequent 

growth) is reduced in direct proportion to the losses caused by entrainment. 

This characterization of ecosystems in terms of a “trophic pyramid” is now 

recognized as a gross oversimplification of reality. In a comprehensive review of 

terrestrial and aquatic food webs, Polis and Strong (1996) stated (p. 815) that “the notion 

that species clearly aggregate into discrete, homogeneous trophic levels is fiction.” 

Rather than being organized into discrete levels, with plants at the base and large 

predators at the top, in real food webs most animals consume organisms from multiple 

trophic levels. Moreover, the food consumed by typical predator species is often derived 

from a combination of plant-based and decomposer-based production, and the species 

consumed change depending on developmental stage and spatial location. The 

characterization of ecosystem structure advocated by Polis and Strong (1996) is 

supported by a wide variety of theoretical and empirical food web studies such as 

Murdoch (1966), Peters (1977), Darnell (1961), Hanski (1987), Baird and Ulanowicz 

1989, Hall and Rafielli (1991), Polis and Holt (1992), Vander Zanden and Vadeboncoeur 

2002, and Thompson et al. 2007. 

The Hudson River ecosystem is consistent with the view of food webs expressed 

by Polis and Strong (1996). Striped bass larvae, for example, feed primarily on small 

invertebrates called “copepods,” (Limburg et al. 1998), which are an important 

component of the zooplankton. Copepods, in turn, feed on both phytoplankton and on 

decomposer microorganisms growing on the surfaces of organic particles suspended in 

the water column. Juvenile striped bass feed on copepods, but also on larger 

invertebrates such as gammarids and chironomids (Gardinier and Hoff, 1982). These 

invertebrates feed on plants and decomposing organic matter, and in addition gammarids 

are active predators on zooplankton and even fish eggs and larvae (Poje et al. 1988). 

Striped bass begin feeding on fish when they reach a length of 76-150 mm, but 

still feed primarily on invertebrates until they reach a length of about 200 mm (Gardinier 

and Hoff, 1982). Other Hudson River fish species similarly feed on a wide variety of 

organisms at different stages of their life cycles. White perch feed primarily on 

invertebrates such as gammarids, but also on fish eggs and larvae and even plants (Bath 

and O’Connor 1985). 
Figure 1. Flows of biomass in an estuary such as the Hudson River, according to the classical “trophic pyramid” the FEIS. Plants are the ultimate source of food for all higher organisms. Small plants (phytoplankton) suspendeconsumed by small invertebrates (zooplankton), which are then consumed by small fish such as bay anchovy. La

striped bass consume bay anchovies. All organisms that die without being consumed by higher organisms are de

organisms such as scavengers (e.g., crabs), bacteria, and fungi. The nutrients released are taken up by plants, to pto support the trophic pyramid. Entrainment “short-circuits” the pyramid, returning entrained organisms directly pool and reducing the food available to predators.

Small Fish

Predators

Zooplankton

Phytoplankton

Scavengers/

Decomposers

Dissolved

Nutrients

Small Fish

Predators

Zooplankton

Phytoplankton

Scavengers/

Decomposers

Dissolved

Nutrients

(a)

no I&E Predators

Zooplankton

Phytoplankton

Scavengers/

Decomposers

Dissolved

Nutrients

Survivors Losses

Reduced predatorabundance caused reduction in prey a

Losses“short-circuto decompopool

(b

with 
1

Juvenile bluefish that enter the Hudson River prey primarily on smaller fish, but 

also consume blue crabs and sand shrimp (Juanes et al. 1995; Buckel and Conover 1997). 

The fish consumed by bluefish include other piscivore species (striped bass), 

planktivorous species (bay anchovy, American shad, and river herring), and benthic 

invertebrate-feeding species (white perch and Atlantic tomcod). 

Figure 2a depicts the flow of biomass according to the more realistic view of the 

Hudson River ecosystem summarized above. In addition to the biomass flow pathways 

shown in Figure 1a, additional flows show the consumption of decomposers by 

zooplankton, and the direct consumption of zooplankton by predatory fish. Figure 2b 

depicts the influence of entrainment on the Hudson River ecosystem, consistent with the 

more complex food web of Figure 2a. Rather than being transferred directly to the 

scavenger/decomposer pool, entrained organisms are available for consumption by 

predators. Fish and invertebrate scavengers that consume entrained organisms are also 

susceptible to predation. Consumption by these organisms retains much of the entrained 

biomass within the food web, greatly reducing the quantity that is lost to decomposers. 

The decomposing organisms themselves may be consumed by invertebrates, even further 

reducing the loss of biomass to the food web. 

Because of the complexity of real food webs, the potential fate of the entrained 

anchovy discussed in the FEIS (p. 54) is actually far more varied, and the impacts much 

lower, than is implied in the FEIS. Since many entrained fish, including fragile species 

such as bay anchovy, are initially alive when returned to the river, the anchovy in 

question could still be consumed by a predator, possibly even the same striped bass that 

would have consumed it had it not been entrained. If not immediately consumed by a 

predator, the anchovy could sink toward the bottom and be consumed by a white perch, 

Atlantic tomcod, or other benthic-feeding fish species, or by a crab or sand shrimp. Any 

of these species would then be capable of performing the anchovy’s function of 

concentrating and distributing nutrients, and could in turn be consumed by a striped bass 

or other predator. If, instead of being consumed, the anchovy were decomposed by 

bacteria and fungi, these microorganisms would themselves be susceptible to grazing by 

invertebrates such as cladocera, copepods, or gammarids, which would in turn be 

available for consumption by striped bass, white perch, bay anchovies, or other fish. Due 

to these complex biomass flow pathways, the effects, if any, of the entrainment of bay 

anchovy and other small fish at the Stations would be diffused throughout the entire 

ecosystem and would be much smaller than implied in the FEIS. 

D.2.4 Influence of cooling water withdrawals on the risk of algal 

blooms 

The FEIS’s concern that algal blooms may be caused by cooling water withdrawals 

is not supported by literature. On pp. 53-54, the FEIS states that losses of small 

planktonic organisms due to entrainment “may be a factor that leads to harmful algal 

blooms.” A paper by Capriulo et al. (2002) is cited in support of this statement. 
Figure 2. Flows of biomass in an estuary according to current ecological science. Most animals are “omnivore

types of organisms at different points in their life cycles. In addition to feeding on fish, striped bass also feed o

scavengers such as crabs and shrimp. Even bacteria and fungi are consumed by zooplankton and other invorganisms are available for consumption both by predators and by other organisms that are in turn consumed by 

of biomass within the food web minimizes any reduction in food available to predators. 

Small Fish

Predators

Zooplankton

Phytoplankton

Scavengers/

Decomposers

Dissolved

Nutrients

(a)

no I&E

Small Fish

Predators

Zooplankton

Phytoplankton

Scavengers/

Decomposers

Dissolved

Nutrients

(a)

no I&E

Predators

Zooplankton

Phytoplankton

Scavengers/

Decomposers

Dissolved

Nutrients

Survivors Losses

Prey reddirect coentraineabundanand scav

wi

Predators

Zooplankton

Phytoplankton

Scavengers/

Decomposers

Dissolved

Nutrients

Survivors Losses

Prey reddirect coentraineabundanand scav

wi
2

This paper does not, in fact, discuss either entrainment or algal blooms. Instead, it 

focuses on the influence of enhanced nutrient inputs on western Long Island Sound, and 

in particular on alternative explanations for the fact that increased nutrient inputs have led 

to increased production of phytoplankton (free-floating algae) and zooplankton, but not to 

increased production of fish. The authors conclude that the excess production of 

planktonic algae and zooplankton is being diverted to microbial decomposition and 

production of ctenophores (gelatinous, predatory organisms related to jellyfish) rather 

than to production of fish. This paper clearly does not support the statement made in the 

FEIS. 

For the effect hypothesized in the FEIS to occur, it would have to be the case that the 

productivity of planktonic algae in the Hudson River was limited at least in part by the 

grazing activities of zooplankton and fish larvae entrained at the Stations. Reduced 

abundance of these grazers could then, according to this hypothesis, result in increased 

production of algae, including the kinds of algae responsible for harmful blooms. 

However, it has long been known that phytoplankton production in the lower Hudson 

River estuary, where the Stations are located, is limited by light penetration and by the 

flushing of suspended phytoplankton out of the river (Moran and Limburg 1986, Gladden 

et al. 1988). Miller and St. John (2006) confirmed through a modeling study that primary 

production in the lower Hudson is limited by light penetration and by flushing. Since 

production is limited by these abiotic factors, removal of grazers by entrainment should 

not lead to increased production of planktonic algae. 

D.2.5 Influence of entrainment on the quantity of organisms present 

within the water column 

The FEIS states broad, unsupported conclusions about the types of organisms that 

are entrained at the Stations. According to p. 54 of the FEIS, cooling water withdrawals 

by Indian Point and other power plants reduce the quantity of organisms present within 

the water column, a process termed “draw-down.” This statement is supported by 

citations to a report from HydroQual (1999). Figures taken from that report show the 

probabilities that particles (e.g., fish eggs or larvae) released into the river at various 

locations will be entrained at a power plant within 7 days following release. Figure 3-7, 

on p. 55 of the FEIS, shows that under low-flow conditions Indian Point can entrain 

particles from locations between RM 20 and RM 70. Figure 3-8, on p. 56 of the FEIS, 

shows that under high-flow conditions particles originating between RM 25 and RM 100 

can be entrained. The FEIS concludes from these figures that drawdown due to cooling 

water withdrawals “dramatically reduces food availability within the ecosystem, and, 

thus, survivability of multiple species over significant stretches of the Hudson River.” 

The FEIS does not explicitly state the kinds of organisms to which this statement 

refers. If it is intended to apply to all organisms, then it conflicts with the conclusions of 

the Nuclear Regulatory Commission (“NRC”) staff in the Draft Supplemental 

Environmental Impact Statement (“DSEIS”) for IP2 and IP3 (USNRC 2009). The 

DSEIS states on p. 4-4 that entrainment of phytoplankton and zooplankton “has never 
3

been found to be a problem at operating nuclear power plants and is not expected to be a 

problem during the license renewal term.” 

As applied only to early life stages of fish, the conclusion stated in the FEIS is 

also invalid, for two reasons. First, as is clearly shown in the two figures cited, the 

probability that any particular particle will be entrained at Indian Point never exceeds 

15%, even at the locations in the immediate vicinity of the plant, and only during low 

flow conditions. Under high flow conditions the maximum probability of entrainment is 

less than 10% in the vicinity of the plant. Second, as discussed in Section D.2.3, 

entrainment does not remove any biomass from the river. Since all biomass is returned to 

the river, there is no reduction in the quantity of organisms present. Even those 

organisms killed or injured by entrainment still are available as food for other organisms. 

If the “drawdown” hypothesized in the FEIS actually occurred, there should be an 

observable reduction in the abundance of entrainable life stages of fish in the river 

regions from which cooling water is withdrawn, as compared to adjacent regions. In fact, 

the available data for the Hudson River provide no evidence for any such reductions. 

Figure V-115 of the DEIS plots the spatial patterns in abundance, taxonomic richness, 

and diversity of larval fish in the Hudson River over the years 1974-1997. None of these 

metrics shows any observable decline in region 4, where the Stations are located, 

compared to adjacent regions 3 and 5. 

D.2.6 Conclusion 

 

 The discussion of ecosystem-level effects on pp. 51-54 of the FEIS is not based 

on any analyses of the biological data available for the Hudson River, or on a realistic 

description of how cooling water withdrawals at a power plant might interact with the 

populations and communities present in the Hudson River. Instead, it is based on invalid 

comparisons and simplistic hypotheses, together with a misleading characterization of 

power plant operations. 

 Power plant cooling systems do not actively seek out specific fish species or large 

concentrations of fish, and do not hunt fish until populations are depleted. Cooling water 

withdrawals at the Stations do not physically alter fish habitat and do not reduce the 

ability of the habitat to support fish. Water withdrawals and consequent entrainment of 

fish cease whenever pumps are shut down, and do not resume until pumps are restarted. 

Even when pumps are operating and water is withdrawn, all of the water and entrained 

organisms are returned to the river, with no evidence of any “drawdown” of organisms in 

the vicinity of Indian Point. 

 The conclusions reached in the FEIS are conjectural and inconsistent with the 

available scientific facts. There is no evidence that any of the effects discussed in the 

FEIS have actually occurred in the Hudson River, and much evidence that any such 

effects, even if they do occur, are immeasurably small. 
4

D.3 References 

Baird, D., and R. L. Ulanowicz. 1989. The seasonal dynamics of the Chesapeake Bay 

ecosystem. Ecological Monographs 59:329-364. 

Bath, D. W., and J. M. O’Connor. 1985. Food preferences of white perch in the Hudson 

River estuary. New York Fish and Game Journal 32:63-70. 

Buckel , J.A., and D. O. Conover. 1997. Movements, feeding period, and daily ration of 

piscivorous young-of-the-year bluefish Pomatomus saltatrix in the Hudson River estuary. 

Fishery Bulletin 95:665-679. 

Capriulo, G. M., G. Smith, R. Troy, G. H. Wikfors, J. Pellet, and C. Yarish. 2002. The 

planktonic food web structure of a temperate zone estuary, and its alteration due to 

eutrophication. Hydrobiologia 475/476:263-333. 

Daniels, R. A., K. E. Limburg, R. E. Schmidt, D. L. Strayer, and R. C. Chambers. 2005. 

Changes in fish assemblages of the tidal Hudson River, New York. Transactions of the 

American Fisheries Society Symposium 45:471-503. 

Darnell, R. M. 1961. Trophic spectrum of an estuarine community, based on studies of 

Lake Ponchartrain, Louisiana. Ecology 42:553-568. 

Daskalov, G. M. 2002. Overfishing drives a trophic cascade in the Black Sea. Marine 

Ecology Progress Series 225:53-63. 

Dayton, P. K., S. Thrush, and F. C. Coleman. 2002. Ecological effects of fishing in 

marine ecosystems of the United States. Prepared for the Pew Oceans Commission. 

Gardinier, M. and T.B. Hoff. 1982. Diet of striped bass in the Hudson River estuary. 

New York Fish and Game Journal. 29:152-165. 

Gladden, J. B., F. R. Cantelmo, J. M. Croom, and R. Shapot. 1988. Evaluation of the 

Hudson River ecosystem in relation to the dynamics of fish populations. American 

Fisheries Society Monograph 4:37-52. 

Hall, S. J., and D. Rafielli 1991. Food-web patterns: Lessons from a species-rich web. 

Journal of Animal Ecology 60:823-841. 

Hanski, I. 1987. Plankton that don’t obey the rules. Trends in Ecology and Evolution 

2:350-351. 

Henderson, P. A., and R. M. Seaby. 2000. Technical comments on the Draft 

Environmental Impact Statement for the State Pollutant Discharge Elimination System 

Permit Renewal for Bowline Point 1&2 Indian Point 2&3 and Roseton 1&2 steam 

generating stations. Pisces Conservation, Ltd. 
5

HydroQual, Inc. 1999. Modeling the entrainment of passive particlesinto Hudson River 

power plants. Prepared for Orange and Rockland Utilities, February, 1999. 

Jackson, J.B.C., M. X. Kirby, W. H. Berger, K. A. Bjorndal, L. W. Botsford, B. J. 

Bourque, R. H. Bradbury, R. Cooke, J. Erlandson, J. A. Estes, T. P. Hughes, S. Kidwell, 

C. B. Lange, H. S. Lenihan, J. M. Pandolfi, C. H. Peterson, R. S. Steneck, M. J. Tegner, 

and R. R. Warner. 2001. Historical overfishing and the recent collapse of coastal 

ecosytems. Science 293:629-638. 

Juanes, F., R. E. Marks, K. A. McKown, and D. O. Conover. 1993. Predation by age-0 

bluefish on age-0 anadromous fishes in the Hudson River estuary. Transactions of the 

American Fisheries Society 122:348-356. 

Limburg, K. E., M. L. Pace, and K. K. Arend. 1998. Growth, mortality, and recruitment 

of larval Morone spp. in relation to food availability and temperature in the Hudson 

River. Fishery Bulletin 97:80-91. 

Lindeman, R. L. 1942. The trophic-dynamic aspect of ecology. Ecology 23:399-417. 

Miller, R. L., and J. P. St. John. 2006. Modeling primary production in the lower Hudson 

River estuary. pp. 140-156 in Levinton, J. S., and J. R. Waldman (eds.) The Hudson River 

Estuary. Cambridge University Press, New York. 

Miller, D., J. Ladd, and W. C. Nieder. 2006. Channel morphology in the Hudson River 

estuary: Historical changes and opportunities for restoration. pp. 29-38 in Waldman, J., 

K. Limburg, and D. Strayer (eds.) Hudson River Fishes and their Environment. 

American Fisheries Society Symposium 51. 

Moran, M. A., and K. E. Limburg. 1986. The Hudson River ecosystem. Pp. 6-49 in 

Limburg, K. E., M. A. Moran, and W. H. McDowell (eds.) The Hudson River Ecosystem. 

Springer-Verlag, New York. 

Murdoch, W. W. 1966. “Community structure, population control, and competition” – a 

critique. The American Naturalist 100:219-226. 

Myers, R. A., and B. Worm. 2003. Rapid worldwide depletion of predatory fish 

communities. Nature 423:280-283. 

Peters, R. H. 1977. The unpredictable problem of tropho-dynamics. Environmental 

Biology of Fishes 2:97-101. 

Pew Oceans Commission. 2003. America’s living oceans: Charting a course for change. 

Poje, G. V., S. A. Riordan, and J. M. O’Connor. 1988. Food habits of the amphipod 

Gammarus tigrinus in the Hudson River and the effects of diet upon its growth and 
6

reproduction. Pp. 255-270 in C. L. Smith (ed.) Fisheries Research in the Hudson River. 

State University of New York Press, Albany, NY. 

Polis, G. A., and R. D. Holt. 1992. Intraguild predation: The dynamics of complex 

trophic interactions. Trends in Ecology and Evolution 7:151-154. 

Polis, G. A., and D. R. Strong. 1996. Food web complexity and community dynamics. 

The American Naturalist 147:813-846. 

Schmidt, R. E., and S. Cooper. 1996. A catalog of barriers to upstream movement of 

migratory fishes in Hudson River tributaries. Final report to the Hudson River 

Foundation, New York, NY. 

Squires, D. F. 1992. Quantifying anthropogenic shoreline modification of the Hudson 

River estuary from European contact to modern time. Coastal Management 20:343-354. 

Steele, J. H., and M. Schumacher. 2000. Ecosystem structure before fishing. Fisheries 

Research 44:201-205. 

Thompson, R. M., M. Hemberg, B. M. Starzomski, and J. B. Shurin. 2007. Trophic levels 

and trophic tangles: The prevalence of omnivory in real food webs. Ecology 88:612-617. 

U.S. Nuclear Regulatory Commission (USNRC). 2009. Generic environmental impact 

statement for license renewal of nuclear plants. Supplement 38. Regarding Indian Point 

Nuclear Generating Unit Nos. 2 and 3. Draft report for comment. 

Vander Zanden, M. J., and Y. Vadeboncoeur. 2002. Fishes as integrators of pelagic and 

benthic food webs in lakes. Ecology 83:2152-2161. 
7 

Attachment D-1 

Supplemental Analyses to Address 

Concerns Regarding 

Validity of CMR Estimates as Measures of Risk to Entrainment, 

Emigration of YOY Striped Bass from the Hudson River, and 

Dynamics of the Bay Anchovy YOY Population in the Hudson River 

Prepared by 

AKRF, Inc. 

Hanover, Maryland 

12/29/09 
8 

CMR Estimates 

 In the AEI Report, estimates of CMRs from the DEIS are used as measures of the 

relative risk of entrainment. 

 Concerns Raised in the ESSA Review 

 ESSA’s review of the DEIS included a critique of the CMR estimates presented in 

the DEIS. They concluded that the CMR estimates, although appropriate measures in 

principal, were unreliable measures of entrainment effects due to details of the method of 

estimation (ESSA 2000, page iv): 

“The shift to accounting for the effects of outages or partial flow 

reductions based on units which reflect the indicator of concern (CMR) is 

a useful and laudable method. Our review however suggests concern with 

several aspects of the proposal and supporting analyses: 

Our review suggests concern with the estimation of entrainment 

which serves as the fundamental basis for the CMR data on which 

the FPP system is based. Specifically, there is considerable 

uncertainty in forecast CMRs due to applications of W parameter 

values from a period with different species distributions and 

possibly different intake rates. Until this concern can be clearly 

resolved, the entrainment estimates for the 1991 to 1997 data series 

(on which the FPP system is based) should be viewed with 

skepticism.” 

 For each entrainable life stage, the W-ratio (W parameter) represents the ratio of 

density in the vicinity to the intake to the overall density in the region adjacent to a power 

plant. For the DEIS, estimates of W-ratios were calculated using the available 

entrainment data (1981-1987). ESSA speculated that a shift in habitat quality (from the 

1980’s to the 1990’s) had caused a shift in nearshore distribution patterns of entrainable 

life stages, and therefore, they concluded the estimated W-ratios could not be used to 

estimate CMRs for the 1990’s. ESSA provided no evidence that a shift in nearshore 

distribution patterns had occurred. Nevertheless, they based a major conclusion of their 

review on that speculation, claiming observed changes in CMR estimates were due to 

biases introduced by shifts in nearshore distribution patterns (ESSA 2000, page 18): 

“As discussed in the beginning of this section, the entrainment estimates 

published in the DEIS suggest a curious decline in the estimation of 

entrainment during the 1990s. If, for example, the habitat change in the 

Hudson River caused a shift to a more inshore distribution of larvae, the 

effect would be relatively lower densities in the areas sampled by the LRS. 
9 

Since inshore densities are predicted from the offshore densities using 

1980s-based regression equations, an overall reduction in predicted larval 

density would result. When combined with a constant value of W (also 

determined during the 1980s) the effect could be to predict reduced 

entrainment at a time when it was actually increasing. This raises 

fundamental concerns regarding estimates of entrainment during the 1990s 

and the prediction of future entrainment with the current model.” (ESSA 

2000, page 18) 

 ESSA did not conduct an analysis of field data to corroborate their conclusion that 

a shift in nearshore distribution patterns was the cause for the lower CMR estimates 

during the 1990’s, nor did they consider alternative hypotheses (e.g., interannual 

variability in freshwater flow rates that affect longitudinal distribution patterns of larvae 

in the River) to explain the lower CMR estimates in the 1990’s. 

 In addition to their primary concern regarding W-ratios, ESSA identified three 

potential sources of uncertainty in input parameter estimates required for the CMR 

calculations: 

 

1) Relative probability of capture (“RPC”) 

2) Unsampled areas 

3) Through-plant mortality 

Each of these identified potential sources of uncertainty was due to limitations in 

available data. For the RPC estimates, species-specific data were not available for all 

RIS. Similarly, the available data on through-plant mortality did not support species- and 

plant-specific estimates for all RIS and all plants addressed in the DEIS. Regarding 

unsampled areas, ESSA stated, “We recognize the difficulty in obtaining a complete field 

data set, and the methods described in the DEIS to provide a complete data set for 

analysis are not unreasonable.” Nevertheless, they still listed unsampled areas as one of 

the “more obvious sources of error.” 

 For each of these potential sources of uncertainty, ESSA provided a narrative 

discussion of the basis for their concern. However, they did not provide any assessment 

of the likely magnitude of uncertainty or bias that might be introduced by each potential 

source, nor of the magnitude of uncertainty or bias that might be introduced collectively 

by all potential sources. 

 New Analyses Confirming Validity of CMR Estimates for Use in AEI Report 

 Nearshore-Offshore Spatial Distribution Patterns 

 An empirical assessment of nearshore-offshore spatial distribution patterns in the 

vicinity of the Station was conducted to address ESSA’s speculation that the apparent 

decline in CMR estimates beginning in 1990 was due to a shift in the nearshore-offshore 
10 

spatial distribution pattern of larvae, which caused CMR estimates to be biased low. If 

there had been a shift in the spatial distribution of entrainable life stages towards the 

nearshore areas after the 1980’s, then the abundance in the nearshore areas should have 

increased relative to the abundance in the offshore areas. For each year from the 1980’s 

and 1990’s post yolk-sac larvae (“PYSL”) abundance in each sampling stratum (i.e., 

channel, bottom, and shoal) of the Indian Point Region was estimated based on stratumspecific PYSL density estimates from the Longitudinal River Survey (“LRS”) and 

estimates of the volume of water in each stratum (ASAAC, 2007). The channel and 

bottom strata are those offshore portions of the river where water depths are greater than 

20 feet. The shoal stratum consists of the nearshore portion of the river where water 

depths are between 10 feet and 20 feet. The portion of the river where water depths are 

less than 10 feet is referred to as the shorezone, and is not sampled by the LRS. The 

shorezone contains less than 3% of the river volume in the Indian Point Region, and the 

shoal stratum contains less than 6% of the river volume in the Indian Point Region 

(ASAAC, 2007, table 2-11). 

 Abundance in the shoal stratum was used as an indicator of relative abundance in 

nearshore areas (because sampling was not conducted in the shorezone), and abundance 

in the channel and bottom strata were used as indicators of relative abundance in the 

offshore areas. For each species and year, the ratio of abundance in the shoal stratum to 

the combined abundance in the channel and bottom strata was used as a measure of 

nearshore-offshore distribution pattern: 

channel channel s y bottom bottom s y

shoal shoal s y

offshore s y

nearshore s y

s y v D v D

v D

A

A

r

, , , ,

, ,

, ,

, ,

, ˆ

ˆ ˆ   

where 

s y r , ˆ is the estimated nearshore-offshore abundance ratio, 

vshoal is the volume of the shoal stratum in the Indian Point Region 

vchannel is the volume of the channel stratum in the Indian Point Region 

vbottom is the volume of the bottom stratum in the Indian Point Region 

Dshoal,s,y is the average PYSL density in the shoal stratum of the Indian 

Point Region for species, s, in year, y, 

Dchannel,s, y is the average PYSL density in the channel stratum of the Indian 

Point Region for species, s, in year, y, 

Dbottom,s,y is the average PYSL density in the bottom stratum of the Indian 

Point Region for species, s, in year, y, 

Estimates of average PYSL density were based on ichthyoplankton sampling in weeks 18 

through 26 (the weeks consistently sampled in all years). 
11 

 The average ratio for the earlier period of years (1981-1987), and approximate 

95% confidence limits for the average ratio were computed as: 





1987

1981

, 1 , ˆ 7

1 ˆ

y

s period s y r r

   , 1 , 1 ˆ 1.96 ˆ s period s period Confidence Limits  r   se r

where 

    , 1 , 1 ˆ var ˆ s period s period se r  r

and 

     

 

 

   



































 

1987

1981

2

, ,

, ,

2

, ,

2 , ,

, 1 , ˆ

ˆ var

ˆ

ˆ var ˆ 49

1

var ˆ

y offshore s y

offshore s y

nearshore s y

nearshore s y

s period s y

A

A

A

A

r  r

Parallel equations were used for the later period of years (1988-1997). 

 The estimated average ratio decreased from the earlier period of years to the later 

period of years for half of the species of interest (American shad, bay anchovy and river 

herring), and increased for half of the species of interest (Atlantic tomcod, striped bass 

and white perch). However, no changes in the estimated average ratio were statistically 

significant (Table D-1-1) for any species (based on overlapping 95% confidence limits). 

These results support the conclusion that there was no systematic shift in the nearshoreoffshore spatial distribution of entrainable larvae, as speculated by ESSA. 

 CMR as Metric of Risk to Entrainment 

 To address the overall validity of the CMR estimates as measures of risk to 

entrainment, an assessment was conducted to determine whether the CMR estimates were 

well correlated with a simple, empirical predictor of entrainment risk based on larval 

location in the river and on Indian Point cooling water withdrawal rates. The empirical 

predictor did not include the three inputs to the CMR estimates that ESSA criticized, i.e., 

RPC, unsampled areas adjustments, and through-plant mortality. 

 For each species, the empirical assessment examined the relationship between: 

1) Estimates of CMR 

2) The proportion of larvae in the river that occurred in Regions 3, 4 and 5 

3) Cooling water flow rates at Indian Point. 

The relationship was examined separately for each species, s, with the following logistic 

regression model: 
12 

  CMRs y Ps y Fs y logit ,   0  1 ,   2 ,

or 

  Ps y Fs y s y

e

CMR 0 1 , 2 , 1

1 ,      

where 

CMRs,y is the CMR estimate for species, s, in year, y, 

Ps,y is an estimate of the proportion of larvae in the river during the 

period of entrainment vulnerability that were in Regions 

3,4 and 5 during year, y, and 

Fs,y is the average monthly cooling water flow rate at Indian Point 

during the period of entrainment vulnerability during year, 

y . 

 The logit transformation was used for the regression because it kept the CMR 

estimates bounded by 0 and 1, while allowing the linear combination of explanatory 

variables to be unbounded. The variable, Ps,y was calculated as a weighted average of the 

proportion in Regions 3, 4 and 5, where the weights represented the relative amount of 

water withdrawn by the Stations from each of the three regions (from Table X-15, 

Appendix VI-I-B, DEIS). The Stations’ flow data from May and June were used to 

represent the period of entrainment vulnerability for American shad, river herring, striped 

bass and white perch; data from April were used for Atlantic tomcod (data from 

ichthyoplankton sampling were not available from earlier months in most years); and data 

from June and July were used for bay anchovy. 

 Results from the regression analyses were highly significant for all species and 

are summarized in Tables D-1-2 and D-1-3. Plots of predicted versus observed values 

from these regressions are presented in Figures D-1-1 to D-1-6. These results show that 

uncertainties in the input parameters identified by ESSA (which were excluded from this 

empirical assessment) did not materially affect the overall patterns of CMR’s as 

indicators of risk to entrainment. Furthermore, there is no indication that the relationship 

between CMR estimates from the DEIS and the key factors affecting risk to entrainment 

(i.e., proportion of larval population in Regions 3, 4 and 5, and Indian Point cooling water 

flow rate) changed beginning in 1991. This result provides additional support for the 

conclusion that any apparent declines in CMR estimates in the 1990’s were simply due to 

inter-annual variability in naturally occurring longitudinal distribution patterns and in 

cooling water flow rates at the Station. 
13 

Striped Bass Indices of Abundance 

 The AEI Report uses indices of striped bass larval abundance from the LRS and 

indices of striped bass juvenile abundance from the Beach Seine Survey (“BSS”) to 

examine the relationship between striped bass larval abundance and resulting juvenile 

abundance. 

Concerns Raised in the ESSA Review 

 The ESSA review challenged the validity of the BSS and NYSDEC’s beach seine 

survey (“JSB”) as providing valid measures of striped bass juvenile abundance. They 

concluded that: 

“In summary, the indices of abundance of juveniles (BSS, JSB, WLI-0 

indices) ... each pertain to a portion of recruitment present in a specific 

habitat. As such, they would not be expected to produce reliable indices of 

abundance of recruitment for the entire Hudson River striped bass 

population.” (ESSA 2000, page 23) 

ESSA did not mention that the Atlantic States Marine Fisheries Commission relies on 

juvenile striped bass indices from the JSB along with juvenile indices from Maryland’s 

and New Jersey’s beach seine surveys to conduct their Atlantic coast striped bass stock 

assessments. The ASMFC’s striped bass stock assessments are the basis for striped bass 

management on the Atlantic coast. 

 ESSA’s claim apparently was based on their belief that age-0 striped bass were 

emigrating from the Hudson River at faster rates since 1988 than in prior years: 

“Changes in the water quality of the Hudson River could have affected the 

reliability of the BSS and JSB as indices of year-class strength. NY harbor 

water quality improvements due in part to sewage treatment in the lower 

Hudson River from RM 20 down to RM 0 in recent years have opened a 

window allowing access to the Long Island habitat (NYSDEC comm.). 

The BSS and JSB may be fine estimates of juvenile densities in the beach 

zones for which they were designed, but fail completely to index yearclass strength because of variable residence time and emigration from the 

sampling area (i.e., more recruitment could have occurred post-1988 than 

actually measured). Thus BSS and JSB may be significantly 

underestimated in recent years.” (Deriso, et.al. 2000, page 3) 

ESSA supported this contention by citing age-0 striped bass data collected by NYSDEC 

in Western Long Island Sound (“WLI-0”): 

“[BSS and JSB] measure juvenile density in the lower Hudson River 

beach seine habitat. The existence of the WLI-0 index indicates that 
14 

neither of the first two indices measure abundance of the entire yearclass.” 

These statements suggest that ESSA found an upward trend in abundance indices from 

the WLI-0 Survey starting after 1988 that could not be explained by changes in the inRiver abundance of age-0 striped bass. 

New Analyses Confirming Validity of BSS Indices of Abundance for Use in 

AEI Report 

 Subsequent to ESSA’s review of the DEIS, Dunning et.al. (2006a) documented 

the presence of striped bass larvae in the East River, and demonstrated that striped bass 

larvae from the lower Hudson River could be passively transported, by tidal currents, to 

the East River and Western Long Island Sound. They found that 12% or more of striped 

bass larvae in the Battery Region of the Hudson River would be transported by tidal 

currents to the upper East River/Western Long Island Sound Region. They also found 

that the abundance of striped bass larvae in the East River was correlated with the 

abundance of larvae in the Battery Region, which in turn was correlated with freshwater 

flow rates in the Hudson River. These results suggest that small age-0 striped bass 

collected by the WLI-0 survey likely were Hudson River fish transported through the 

East River as larvae. 

 To address the question of whether increases in striped bass age-0 abundance 

indices from the WLI-0 Survey since 1988 were due to increases in the emigration rate 

from the Hudson River, the relationship between: 

1) WLI-0 age-0 striped bass abundance indices (from J.B. Socrates, 2005), and 

2) Striped bass larval abundance in the Hudson River, and Hudson River 

freshwater flow when striped bass larvae are abundant. 

The relationship was examined with the following non-linear regression model: 

  GJune y WLI y Ly

1 ,

0 exp   

where 

WLI,y is the WLI-0 abundance index for July through October for striped 

bass in year, y, 

Ly is the Hudson River striped bass post yolk sac larval abundance 

index for year, y, and 

GJune,y is the monthly freshwater flow (measured by USGS at Green 

Island) for June in year, y. 
15 

In this model, the abundance of juvenile striped bass in Western Long Island Sound in 

each year is directly proportional to the striped bass post yolk sac larvae abundance in the 

Hudson River in that year. The proportionality depends only on the freshwater flow rate 

in June of that year. The exponential term allows the relationship between freshwater 

flow rate and the proportionality to be non-linear. 

 Results from this regression analyses were highly significant and are summarized 

in Table D-1-4. Plots of predicted versus observed values from the regression are 

presented in Figures D-1-7a and D-1-7b. These results clearly indicate that the 

abundance of age-0 striped bass in Western Long Island Sound can be adequately 

predicted from the abundance pattern of larval striped bass in the Hudson River and the 

level of freshwater flow in June. Furthermore, there is no indication of a change in 

emigration rate, unrelated to changes in freshwater flow, since 1988 (Figure D-1-8). Any 

apparent upward trend in abundance of age-0 striped bass in Western Long Island Sound 

can be explained by changes in larval abundance and freshwater flow rates in the Hudson 

River. 

 The results from this analysis together with the findings of the Dunning et.al. 

(2006) study, and the reliance by the ASMFC on beach seine survey indices of 

abundance for striped bass for the purpose of managing the Atlantic coast striped bass 

stock, provide confirmation that the BSS indices of striped bass juvenile abundance are 

valid measures of striped bass juvenile abundance as used in the AEI Report. 

Bay Anchovy Abundance Trends 

 The AEI Report concluded that entrainment of bay anchovy at Indian Point could 

be rejected as an explanation for long-term trends in the abundance of age-0 bay anchovy 

in the Hudson River. The AEI Report also concluded that predation by striped bass was a 

likely explanation for trends in abundance of age-0 bay anchovy. 

 Concerns Raised in the ESSA Review 

 ESSA’s review of the DEIS included a critique of the discussion of factors 

affecting bay anchovy abundance in the Hudson River, including striped bass predation: 

“Predation by PYSL and YOY striped bass should be one of the major 

influences on the abundance of YOY bay anchovy in the Hudson River.” 

“The PYSL index for striped bass ranged from 1.48 to 15.40 during the 

period from 1988 through 1997 and the regression was statistically 

significant (p-0.010). The predation hypothesis explained about 60% of 

the variation in the abundance of YOY bay anchovy (R2 = 0.580).” (page 

V-115, DEIS) 
16 

ESSA’s critique also addressed Hudson River immigration/emigration of the midAtlantic coastal stock of bay anchovy: 

“Bay anchovy are part of a coastal population that spawns not only in the 

Hudson River but in many other parts of the Hudson-Raritan estuary 

complex. ... the abundance of anchovy within the river may change 

continually, due to movements of anchovy into and out of the estuary.” 

(page V-116, DEIS) 

ESSA dismissed these claims in the DEIS, citing shortcomings in the underlying 

analyses. Regarding striped bass predation, ESSA concluded: 

“We found the analysis difficult to follow and unconvincing. ... For 

example, it does not present the underlying model, discuss the statistical 

uncertainty of the data, cite relevant literature, or refer to any previous 

DEIS work that might lend support to the approach taken (e.g., previous 

technical workshops).” (page 8, Parnell and Marmorek, 2000) 

Regarding bay anchovy immigration/emigration, ESSA concluded: 

“We find the methods and results tenuous and feel the results do not 

support the discussion in Chapter V-G. Chapter V-G also assumes that 

entrainment of bay anchovy is offset by immigration from a larger coastal 

stock, but presents no evidence that supports this assumption.” (page 1, 

Parnell and Marmorek, 2000) 

 ESSA’s review of the DEIS also included a critique of an analysis of striped bass 

predation on bay anchovy conducted by Dr. Kenneth Rose (Appendix VI-4-D, DEIS). 

Again, ESSA dismissed the conclusions of this analysis, citing shortcomings of the 

analysis: 

“We find the results of bay anchovy population (production forgone) 

modeling to be speculative for several reasons. ... The DEIS analysis 

greatly overestimates the predatory demand of striped bass and bluefish 

by: 1) using an incorrect striped bass age-structure, 2) applying the highest 

observed values for the contribution of bay anchovy to the diet of striped 

bass, and 3) estimating river-wide abundance of striped bass and bluefish 

using near-shore striped bass and bluefish densities and river-wide 

volume. The analysis of entrainment effects on the daily biomass of bay 

anchovy attempts to address the dynamic changes in entrainment and 

predators’ requirements missed in the analysis of predatory demand. 

However, the analysis assumes that all natural mortality is due to 

predation and this overestimates true predation. For example, the fact that 

spawner immigration is required in the model to avoid population 
17 

extinction may mean that mortality is set too high elsewhere.” (page 22, 

ESSA 2000). 

 Although the ESSA review of the DEIS challenged the claims in the DEIS that 

striped bass predation and immigration/emigration by the mid-Atlantic bay anchovy stock 

were major factors affecting bay anchovy abundance in the Hudson River, ESSA did not 

provide any evidence to refute these claims. 

 New Analyses Regarding Trends in Bay Anchovy Abundance 

 Subsequent to ESSA’s review of the DEIS, Dunning et.al. (2006b) documented 

the presence of bay anchovy eggs and larvae in New York Harbor, the East River, and 

Long Island Sound. They found that the peak abundance of bay anchovy eggs and larvae 

in nearby waterways were about eight times larger than those in the Hudson River. That 

finding clearly supports the proposition that bay anchovy abundance in the Hudson River 

influenced greatly by immigration/emigration by the mid-Atlantic coastal stock. 

 The likely nature of immigration/emigration of the mid-Atlantic coastal stock was 

examined further with an empirical assessment of the relationship between larval 

abundance in the Hudson River and salinity and temperature in the River. The purpose of 

the empirical assessment was to determine whether bay anchovy larval abundance in the 

Hudson River could be predicted by salinity, freshwater flow and temperature. If bay 

anchovy in the Hudson River are only a small fraction of the mid-Atlantic stock, and if 

they enter the Hudson River opportunistically depending on annual salinity, freshwater 

flow and temperature conditions, then larval abundance would be correlated with salinity, 

freshwater flow and temperature. 

 The empirical assessment examined the relationship between: 

1) Bay anchovy index of PYSL abundance, and 

2) Three measures of physical properties of the Hudson River during the spring: 

a) The proportion of the river with salinity greater than 5 ppt during the 

spring (i.e., weeks 18 through 26), 

b) The freshwater flow rate in June, and 

c) The proportion of the river with temperature greater than 75o F during 

the spring (i.e., weeks 18 through 26). 

The relationship was examined with the following log-linear regression model: 

  e PYSLy 0 1RSy 2GJune, y 3RTy log        

where 

PYSLy is the bay anchovy PYSL abundance index for year, y, 
18 

RSy is an estimate of the proportion of the river with salinity greater 

than 5 ppt during the spring (i.e., weeks 18 through 26) in 

year, y, 

GJune,y is the monthly freshwater flow (measured by USGS at Green 

Island) for June in year, y, and

RTy is an estimate of the proportion of the river with temperature 

greater than 75o

F during the spring (i.e., weeks 18 through 

26) in year, y. 

A log-linear model was used to allow for non-linear relationships between the response 

and explanatory variables. The variable, RSy was calculated using the following formula: 

W y

W

W W

R S s

r s

r S s

r s r s W y

W

W W

W y

y

R

r

V

V

R , 12

1

,

12

1

, , , ,

,

*

*

1 max

min

max

min



































































 





























 

 

 

 

 

 



where 

Vr,S is the volume of region r and stratum s, 

r s  S defines the subset of strata that were consistently sampled within 

region r, 

r,s,W , y = 1 if the average salinity in region r, stratum s, week W and year, 

y, was greater than 5 ppt, 

r,s,W , y = 0 otherwise, and 

 *

W , y = 1 if all 12 standard regions and all standard strata (a total of 27 

region-strata combinations) were sampled in week W of 

year y, and 

 *

W , y = 0 otherwise. 

The variable, RTy was calculated using the same method, but with the term, r,s,W , y , 

redefined as: 
19 

r,s,W , y = 1 if the average water temperature in region r, stratum s, week 

W and year, y, was greater than 75o F, 

r,s,W , y = 0 otherwise, and 

 Results from the regression analyses were statistically significant and are 

summarized in Table D-1-5. Plots of predicted versus observed values from these 

regressions are presented in Figures D-1-9a and D-1-9b. These results, together with the 

findings of Dunning et.al. (2006b) support the proposition that bay anchovy in the 

Hudson River are only a small fraction of the mid-Atlantic stock, that enter the Hudson 

River opportunistically depending on annual physical conditions of the Hudson River. 

 An additional analysis was conducted to examine the possible effects of 

entrainment at the Stations and striped bass predation on juvenile abundance of bay 

anchovy. This additional empirical assessment examined of the relationship between: 

1) Bay anchovy juvenile abundance in the Hudson River, and 

2) Four potential predictor variables: 

a) Bay anchovy PYSL abundance, 

b) Extent of the Hudson River occupied by PYSL bay anchovy, 

c) Entrainment at Indian Point (as measured by CMR), and 

d) Striped bass predation pressure (as measured by the striped bass PYSL 

index of abundance). 

This relationship was examined in three steps. First, a base relationship was examined 

that included only PYSL abundance and the extent of the river occupied by PYSL bay 

anchovy as predictor variables. The base relationship was examined with the following 

log-linear regression equation: 

  e y PYSLy Z y JUV 0 1 2 log      

where 

JUVy is the index of abundance of bay anchovy juveniles in year, y, 

based on data from the FSS, and 

Zy is a measure of the extent of the river occupied by PYSL bay 

anchovy. 

A log-linear model was used to allow for non-linear relationships between the response 

and explanatory variables. The variable Zy was computed as an abundance-weighted 

average region number, where the region-specific proportion of the riverwide abundance 
20 

of PYSL was used as the weight for each region. Larger values of Zy indicate the 

distribution of bay anchovy PYSL extended farther upriver. Results from the base 

regression analysis showed that the proportion of the river occupied by PYSL bay 

anchovy was statistically significant, but bay anchovy PYSL abundance per se was not 

statistically significant for predicting juvenile abundance (Table D-1-6). Therefore, the 

term for bay anchovy PYSL abundance was not included in the last two steps of the 

analysis. 

 Next, the potential effect of entrainment at Indian Point was examined by adding 

annual estimates of bay anchovy CMR (CMRy) to the regression equation: 

  e y Z y CMRy JUV 0 1 2 log      

to determine whether the inclusion of entrainment effects improved the ability to predict 

bay anchovy juvenile abundance. If the Stations’ entrainment affected survival from 

PYSL to the juvenile life stage, including a term for entrainment in the regression 

equation should improve the predictions. 

 The third step was to examine the potential effect of striped bass predation by 

adding the striped bass PYSL abundance index (as a measure of striped bass predation) to 

the regression equation: 

  e y Z y Ly JUV 0 1 2 log      

to determine whether the inclusion of striped bass predation effects improved the ability 

to predict bay anchovy juvenile abundance. If striped bass predation affected survival 

from PYSL to the juvenile life stage, including a term for striped bass predation in the 

regression equation should improve the predictions. 

 Results from this series regression analyses are summarized in Tables D-1-6 

through D-1-8. The results from the base regression analysis indicate that juvenile bay 

anchovy abundance depends on how much of the river is occupied by PYSL bay 

anchovy, and that bay anchovy PYSL abundance, per se, is not a good predictor of 

juvenile abundance. This result suggests that in years with high PYSL abundance 

concentrated downriver, juvenile abundance is not likely to be high as well. However, in 

years with similarly high PYSL abundance spread over many regions, juvenile abundance 

is likely to be high. 

 The term for Indian Point entrainment was not statistically significant (p=0.7593), 

indicating that the Stations’ entrainment did not have a significant effect on bay anchovy 

survival from PYSL to the juvenile life stage. However, the term for striped bass 

predation was statistically significant (p=0024), indicating that striped bass predation had 

a significant effect on bay anchovy survival from PYSL to the juvenile life stage. 
21 

Literature Cited 

ASAAC. 2007. 2005 year class report for the Hudson River estuary monitoring 

program. Prepared for Dynegy Roseton L.L.C. 

Deriso, R.B., D.R. Marmorek, and I. Parnell. 2000. Review of the Assessment of Striped 

Bass. Companion Report to a Review of the DEIS for SPDES Permits for three 

Hudson River Generating Stations. Prepared by ESSA Technologies Ltd., 

Vancouver, BC, for NYSDEC, Albany, NY. 6 pp. 

Dunning, D.J., Q.E. Ross, A.F. Blumberg, and D.G. Heimbuch. 2006a. Transport of 

striped bass larvae out of the Lower Hudson estuary. American Fisheries Society 

Symposium 51:273-286. 

Dunning, D.J., Q.E. Ross, M.T. Mattson, and D.G. Heimbuch. 2006b. Distribution and 

abundance of bay anchovy eggs and larvae in the Hudson River and nearby 

waterways. American Fisheries Society Symposium 51:215-226. 

ESSA Technologies Ltd. 2000. Review of the Draft Environmental Impact Statement for 

SPDES Permits for the Bowline Point 1 & 2, Indian Point 2 & 3, and Roseton 1 & 

2 Steam Electric Generating Stations. Prepared for NYSDEC, Albany NY. 31 pp. 

Parnell, I. and D.R. Marmorek. 2000. Review of the Assessment of Bay Anchovy. 

Companion Report to a Review of the DEIS for SPDES Permits for three Hudson 

River Generating Stations. Prepared by ESSA Technologies Ltd., Vancouver, BC, 

for NYSDEC, Albany, NY. 9 pp. 

J.B. Socrates. 2005. An investigation of the movements and growth of the 2003 Hudson 

River year class in Western Long Island bays. A study of the striped bass in the 

marine district of New York State. Annual report for PL89-304, project AFC-29. 
22 

Tables 

Table D-1-1. Results from assessment of ratio of PYSL abundance in offshore (channel 

and bottom strata) and nearshore (shoal stratum) areas of the Indian Point Region 

of the Hudson River. 

Species Average Abundance Ratio 

(nearshore/offshore) 

1980-1989 

Average Abundance Ratio 

(nearshore/offshore) 

1990-1990 

Lower 

95% 

Confidence 

Limit 

Estimate Upper 

95% 

Confidence 

Limit 

Lower 

95% 

Confidence 

Limit 

Estimate Upper 

95% 

Confidence 

Limit 

American 

Shad 

0.095 0.196 0.300 0.033 0.125 0.216 

Atlantic 

Tomcod 

0.001 0.010 0.020 -0.002 0.035 0.071 

Bay 

Anchovy 

0.028 0.084 0.139 0.045 0.055 0.064 

River 

Herring 

0.035 0.149 0.263 0.062 0.096 0.131 

Striped 

Bass 

0.040 0.066 0.092 0.059 0.075 0.091 

White 

Perch 

0.039 0.051 0.063 0.043 0.052 0.061 
23 

Table D-1-2. Results from non-linear regression (response variable = CMRs,y) analyses 

of annual CMR estimates (CMRs,y) with proportion of larval population in regions 

3,4 and 5 (Ps,y), and the Stations’ cooling water flow (Fs,y) as predictor variables. 

Species Overall Regression Individual Parameter Estimates with 

Significance Level [Pr>|t|] 

R2 Pr>F  0

(intercept) 

1

(Ps,y) 

 2

(Fs,y) 

American 

Shad 

0.80 <0.0001 -5.79 

[<0.0001] 

26.48 

[<0.0001] 

5.2x10-6

[0.7907] 

Atlantic 

Tomcod 

0.79 <0.0001 -3.32 

[<0.0001] 

5.60 

[<0.0001] 

2.4x10-5

[<0.0001] 

Bay 

Anchovy 

0.68 <0.0001 -3.64 

[<0.0001] 

1.50 

[0.0060] 

2.5x10-5

[<0.0001] 

River 

Herring 

0.83 <0.0001 -5.80 

[<0.0001] 

31.99 

[<0.0001] 

2.3x10-5

[0.0003] 

Striped Bass 0.60 <0.0001 -4.33 

[<0.0001] 

4.38 

[0.0137] 

2.5x10-5

[0.0002] 

White Perch 0.75 <0.0001 -4.96 

[<0.0001] 

18.60 

[<0.0001] 

2.3x10-5

[0.0001] 
24 

Table D-1-3. Results from linear regression (response variable = logit(CMRs,y)) analyses 

of annual CMR estimates (CMRs,y) with proportion of larval population in regions 

3,4 and 5 (Ps,y), and the Stations’ cooling water flow (Fs,y) as predictor variables. 

Species Overall Regression Individual Parameter Estimates with 

Significance Level [Pr>|t|] 

R2 Pr>F  0

(intercept) 

1

(Ps,y) 

 2

(Fs,y) 

American 

Shad 

0.46 0.0008 -6.92 

[<0.0001] 

36.89 

[0.0004] 

1.5x10-5

[0.2381] 

Atlantic 

Tomcod 

0.76 <0.0001 -3.32 

[<0.0001] 

5.07 

[<0.0001] 

2.5x10-5

[<0.0001] 

Bay 

Anchovy 

0.71 <0.0001 -3.85 

[<0.0001] 

1.71 

[0.0024] 

2.7x10-5

[<0.0001] 

River 

Herring 

0.61 <0.0001 -6.57 

[<0.0001] 

65.25 

[<0.0001] 

1.9x10-5

[0.0871] 

Striped Bass 0.54 <0.0001 -4.43 

[<0.0001] 

3.90 

[0.0266] 

2.8x10-5

[<0.0001] 

White Perch 0.76 <0.0001 -5.38 

[<0.0001] 

22.49 

[<0.0001] 

2.6x10-5

[<0.0001] 
25 

Table D-1-4. Results from regression analysis of annual estimates of striped bass 

juveniles in Western Long Island Sound (WLIy) with striped bass PYSL 

abundance index (Ly) and freshwater flow in June (GJune,y) as predictor variables. 

Overall Regression Individual Parameter Estimates with 

Significance Level [Pr>|t|] 

R2 Pr>F  0

(scaling constant)

1

(GJune,y) 

0.97 <0.0001 4.87x10-12

[<0.0001] 

0.1839 

[<0.0001] 
26 

Table D-1-5. Results from regression analysis of annual estimates of bay anchovy PYSL 

abundance (PYSLy) with proportion of the river with salinity greater than 5 ppt in 

the spring (RSy), freshwater flow in June, and proportion of the river with 

temperature greater than 75o

 F in the spring (RTy) as the predictor variables. 

Response 

Variable 

[Analysis 

Method] 

Overall Regression Individual Parameter Estimates with 

Significance Level [Pr>|t|] 

R2 Pr>F  0

(intercept) 

1

(RSy) 

 2

(GJune,y) 

 3

(RTy) 

ln(PYSLy) 

[Linear 

Regression] 

0.65 <0.0001 17.4437 

[<0.0001] 

12.4662 

[0.0049] 

-8.99x10-5 

[0.0521] 

11.5884 

[0.0040] 

PYSLy 

[Non-Linear 

Regression] 

0.97 <0.0001 19.7984 

[<0.0001] 

3.7096 

[0.1014] 

-0.0001 

[.0209] 

9.1256 

[<0.0001]

Table D-1-6. Results from regression analysis of annual estimates of juvenile bay 

anchovy abundance (JUVy) with bay anchovy PYSL abundance (PYSLy) and 

extent of river occupied by PYSL (Zy) as the predictor variables. 

Response 

Variable 

[Analysis 

Method] 

Overall Regression Individual Parameter Estimates with 

Significance Level [Pr>|t|] 

R2 Pr>F  0

(intercept) 

1

(PYSLy) 

 2

(Zy) 

ln(JUVy) 

[Linear 

Regression] 

0.37 0.0237 18.0424 

[<0.0001] 

-3.15x10-11

[0.7034] 

0.4384 

[0.0077] 

JUVy 

[Non-Linear 

Regression] 

0.46 <0.0001 18.0423 

[<0.0001] 

-3.50x10-11

[0.6238] 

0.4629 

[0.0009] 
27 

Table D-1-7. Results from regression analysis of annual estimates of juvenile bay 

anchovy abundance (JUVy) with the extent of river occupied by bay anchovy 

PYSL (Zy), and the Stations’ entrainment (CMRy) as the predictor variables. 

Response 

Variable 

[Analysis 

Method] 

Overall Regression Individual Parameter Estimates with 

Significance Level [Pr>|t|] 

R2 Pr>F  0

(intercept) 

1

(Zy) 

 2

(CMRy) 

ln(JUVy) 

[Linear 

Regression] 

0.37 0.0243 18.1220 

[<0.0001] 

0.4294 

[0.0073] 

-0.0070 

[0.7593] 

JUVy 

[Non-Linear 

Regression] 

0.45 <0.0001 18.0210 

[<0.0001] 

0.4558 

[0.0034] 

0.0015 

[0.9418] 

Table D-1-8. Results from regression analysis of annual estimates of juvenile bay 

anchovy abundance (JUVy) with the extent of river occupied by bay anchovy 

PYSL (Zy), and striped bass predation (Ly) as the predictor variables. 

Response 

Variable 

[Analysis 

Method] 

Overall Regression Individual Parameter Estimates with 

Significance Level [Pr>|t|] 

R2 Pr>F  0

(intercept) 

1

(Zy) 

 2

(Ly) 

ln(JUVy) 

[Linear 

Regression] 

0.65 0.0002 18.7277 

[<0.0001] 

0.2769 

[0.0235] 

-0.74x10-10

[0.0024] 

JUVy 

[Non-Linear 

Regression] 

0.57 <0.0001 18.5615 

[<0.0001] 

0.3394 

[0.0061] 

-1.42x10-10

[0.0742] 
28 

Figures 

Figure D-1-1. Results of regression analysis of American shad CMR estimates with 

proportion of PYSL in regions 3,4 and 5; and the Stations’ cooling water flow as 

predictor variables. 

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

American Shad CMR

Prediction Based on

Indian Point Cooling Water Flows and

Proportion of PYSL in Regions 3,4 and 5

CMR Estimate

P

r

e

d

i

c

t

e

d

C

M

R

1975-1990

1991-2002
29 

Figure D-1-2. Results of regression analysis of Atlantic tomcod CMR estimates with 

proportion of PYSL in regions 3,4 and 5; and the Stations’ cooling water flow as 

predictor variables. 

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35

Atlantic Tomcod CMR

Prediction Based on

Indian Point Cooling Water Flows and

Proportion of PYSL in Regions 3,4 and 5

CMR Estimate

P

r

e

d

i

c

t

e

d

C

M

R

1975-1990

1991-2002
30 

Figure D-1-3. Results of regression analysis of bay anchovy CMR estimates with 

proportion of PYSL in regions 3,4 and 5; and the Stations’ cooling water flow as 

predictor variables. 

0.00

0.05

0.10

0.15

0.20

0.25

0.00 0.05 0.10 0.15 0.20 0.25

Bay Anchovy CMR

Prediction Based on

Indian Point Cooling Water Flows and

Proportion of PYSL in Regions 3,4 and 5

CMR Estimate

P

r

e

d

i

c

t

e

d

C

M

R

1975-1990

1991-2002
31 

Figure D-1-4. Results of regression analysis of river herring CMR estimates with 

proportion of PYSL in regions 3,4 and 5; and the Stations’ cooling water flow as 

predictor variables. 

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

River Herring CMR

Prediction Based on

Indian Point Cooling Water Flows and

Proportion of PYSL in Regions 3,4 and 5

CMR Estimate

P

r

e

d

i

c

t

e

d

C

M

R

1975-1990

1991-2002
32 

Figure D-1-5. Results of regression analysis of striped bass CMR estimates with 

proportion of PYSL in regions 3,4 and 5; and the Stations’ cooling water flow as 

predictor variables. 

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20

Striped Bass CMR

Prediction Based on

Indian Point Cooling Water Flows and

Proportion of PYSL in Regions 3,4 and 5

CMR Estimate

P

r

e

d

i

c

t

e

d

C

M

R

1975-1990

1991-2002
33 

Figure D-1-6. Results of regression analysis of white perch CMR estimates with 

proportion of PYSL in regions 3,4 and 5; and the Stations’ cooling water flow as 

predictor variables. 

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18

White Perch CMR

Prediction Based on

Indian Point Cooling Water Flows and

Proportion of PYSL in Regions 3,4 and 5

CMR Estimate

P

r

e

d

i

c

t

e

d

C

M

R

1975-1990

1991-2002
34 

Figure D-1-7a. Results of regression analysis of abundance index for striped bass young 

of year (“YOY”) in Western Long Island Sound with Hudson River striped bass 

PYSL index of abundance and freshwater flow in June as predictor variables. 

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0

WLIS age-0 abundance index

P

r

e

d

i

c

t

e

d

W

L

I

S

a

g

e

-

0

a

b

u

n

d

a

n

c

e

i

n

d

e

x

1984-1988

1989-2004

Striped Bass Juvenile Abundance in

Western Long Island Sound

Prediction Based on

PYSL Abundance and

Freshwater Flow in June
35 

Figure D-1-7a. Results of regression analysis of abundance index for striped bass YOY 

in Western Long Island Sound with Hudson River striped bass PYSL index of 

abundance and freshwater flow in June as predictor variables. Plotted on 

logarithmic scale. 

0.1

1.0

10.0

100.0

0.1 1.0 10.0 100.0

WLIS age-0 abundance index

P

r

e

d

i

c

t

e

d

W

L

I

S

a

g

e

-

0

a

b

u

n

d

a

n

c

e

i

n

d

e

x

1987-1988

1989-2004

Striped Bass Juvenile Abundance in

Western Long Island Sound

(plotted on log scale)

Prediction Based on

PYSL Abundance and

Freshwater Flow in June
36 

Figure D-1-8. Ratio of: 1) index of abundance of YOY striped bass in Western Long 

Island Sound to 2) index of abundance of PYSL striped bass in the Hudson River; 

predicted by freshwater flow in June. Relationship based on results of regression 

analysis depicted in Figure D-1-7. 

0.0

1.0

2.0

3.0

4.0

5.0

6.0

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000 45,000

Green Island Flow in June (cfs)

P

r

e

d

i

c

t

e

d

R

a

t

i

o

o

f

W

L

I

S

/

P

Y

S

L

I

n

d

i

c

e

s

(

x

1

0

9)

1984-1988

1989-2004

Predicted Ratio of 

Juvenile striped bass abundance in WLIS to 

PYSL striped bass abundance in Hudson River

Based on Freshwater Flow in June
37 

Figure D-1-9a. Results of regression analysis of bay anchovy PYSL abundance in the 

Hudson River with salinity, freshwater flow and water temperature as predictor 

variables. 

0.0E+00

1.0E+09

2.0E+09

3.0E+09

4.0E+09

5.0E+09

6.0E+09

0.0E+00 1.0E+09 2.0E+09 3.0E+09 4.0E+09 5.0E+09 6.0E+09

PYSL Index

P

r

e

d

i

c

t

e

d

P

Y

S

L

I

n

d

e

x

1974-1990

1991-2005

Bay Anchovy PYSL Abundance

Prediction Based on

Salinity, Freshwater Flow, and

Water Temperature
38 

Figure D-1-9b. Results of regression analysis of bay anchovy PYSL abundance in the 

Hudson River with salinity, freshwater flow and water temperature as predictor 

variables. Plotted on logarithmic scale. 

12.0

14.0

16.0

18.0

20.0

22.0

24.0

12.0 14.0 16.0 18.0 20.0 22.0 24.0

PYSL Index (loge)

P

r

e

d

i

c

t

e

d

P

Y

S

L

I

n

d

e

x

(

l

o

g

e

)

1974-1990

1991-2005

Bay Anchovy PYSL Abundance

Prediction Based on

Salinity, Freshwater Flow, and

Water Temperature