Evaluation of Impingement Survival on the HydroloxTM Traveling 

Water Screen at the E.F. Barrett Generating Station 

 October 2007 – June 2008 

Final Report 

National Grid 

Environmental Engineering Department 

175 East Old Country Road 

Hicksville, NY 11801 

and 

Intralox 

301 Plantation Road 

Harahan, LA 70123 

Prepared by: 

ASA Analysis & Communication, Inc. 

5 Fairlawn Drive, Suite 205 

Washingtonville, New York 10992 

November 2008 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

i

EXECUTIVE SUMMARY 

In the summer of 2007, a new type of intake screen was installed in one intake forebay at Unit 2 

of the E.F. Barrett Generating Station to test full-scale performance. This screen consists of a 

continuous strand of HydroloxTM engineered polymer screen material that was brick laid in 

modules connected together at the hinges by polymer rods. Fish handling scoops similar to 

modified Ristroph buckets are attached to the base of each screen frame and are designed 

with a low pressure wash to gently return impinged aquatic organisms to the source waterbody 

with minimal injuries. After that, a high pressure spray header directed from behind the screen 

cleans the remaining debris into a separate debris trough. Potential advantages of this screen 

include: 

• Reduced operating and maintenance costs; 

• Improved debris handling characteristics yielding increased plant operating efficiency; 

and, 

• Possible reduced mortality of impinged organisms returned to the source waterbody. 

The other intake forebay at Barrett Unit 2 retained the existing conventional traveling water 

screen for comparison. 

From October 2007 through June 2008, a special study was conducted at Unit 2 to monitoring 

the survival of impinged fish from both the Hydrolox and the conventional traveling screen. 

Monitoring was scheduled weekly whenever either screen was operating. Collections were 

scheduled at night when impingement rates were typically highest. During each sampling 

event, fish were carefully collected from the screenwash discharge screen and classified into 

one of three categories: live, stunned and dead. All live and stunned fish were retained in a 

special holding facility to determine subsequent mortality over 48 hours. 

The results of this study demonstrate that survival of fish impinged on the Hydrolox screen at 

Barrett was generally near the upper bound of estimates reported in other studies and 

consistently equal to or greater than that found on the conventional traveling screen. Relatively 

low survival was only observed for Atlantic menhaden, a species known to be highly susceptible 

to stress-related mortality. However, even for this delicate species, survival from the Hydrolox 

screen was higher than that observed on the conventional screen. With the exception of bay 

anchovy, another known delicate species, no other individuals died after 48-hours of being 

impinged on the Hydrolox screen. These results suggest that impingement survival for these 

other species should also be high and possibly comparable to that observed for the more 

abundance species. This study included a suite of fish species commonly impinged at cooling 

water intakes located in coastal areas of the Northeast. 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

ii

TABLE OF CONTENTS 

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

2. Facility Description................................................................................................... 2

3. Sampling Methods ................................................................................................... 3

4. Results and Discussion............................................................................................ 4

5. Literature Cited....................................................................................................... 12

Appendix A Data Summary 13 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

iii

LIST OF FIGURES 

Figure 1 Characteristics of the HydroloxTM screen installed at the Barrett Generating Station, 

2007. .....................................................................................................................................9

Figure 2 Seasonal distribution of the most abundant species collected in impingement survival 

sampling at Barrett, Oct 2007 - Jun 2008. ..........................................................................10

Figure 3 Length frequency distributions of the most abundant species collected in impingement 

survival sampling at Barrett, Oct 2007 – Jun 2008. ............................................................11
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

iv

LIST OF TABLES 

Table 1 Dates of impingement survival collections and coincident water quality measurements 

at the E.F. Barrett Generating Station, Oct 2007 – Jun 2007. ..............................................6

Table 2 Numbers and length ranges of fish collected in impingement survival monitoring at the 

E.F. Barrett Generating Station, Oct 2007 – Jun 2007. ........................................................7

Table 3 Estimates of extended (48-hour) impingement survival for the ten most abundant 

species collected in impingement survival monitoring at the E.F. Barrett Generating Station, 

Oct 2007 – Jun 2007.............................................................................................................8
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

1 Introduction

1. INTRODUCTION 

The operation of cooling water intake structures is regulated under Section 316(b) of the Clean 

Water Act. This section requires “that the location, design, construction, and capacity of cooling 

water intake structures reflect the best technology available (BTA) for minimizing adverse 

environmental impact” (AEI). Operation of these cooling water intake structures is permitted 

under the National Pollutant Discharge Elimination System (NPDES) administered by the US 

Environmental Protection Agency (USEPA). In New York, the responsibility for the day-to-day 

operation of NPDES has been delegated to the New York State Department of Environmental 

Conservation (NYSDEC), and the requirement for BTA is administered pursuant to regulations 

set forth at 6 NYCRR 704.5. 

These cooling water intake structures have been traditionally protected by vertical traveling 

water screens composed of a continuous band of steel mesh screening. The purpose of these 

screens is to prevent the passage of debris and aquatic organisms into the cooling water 

system along with the cooling water flow. This debris and entrapped aquatic organisms are 

then washed off of these screens by high-pressure water jets and collected in wash water 

sluices. The entrapment of aquatic organisms against these intake screens is a process called 

impingement. While this debris and impinged organisms at many steam-electric facilities are 

returned to the source waterbody, the process of impingement can result in the mortality of 

some aquatic organisms. This mortality from impingement is one of the issues addressed under 

§316(b). 

HydroloxTM is a product line of engineered polymer water screens developed by Intralox LLC, 

the inventor and the world’s largest manufacturer of modular plastic belting. Intralox developed 

a new Hydrolox intake screen design which offered several potential advantages to operators of 

cooling water intake structures at steam-electric generating facilities. These potential 

advantages include: 

• Reduced operating and maintenance costs; 

• Improved debris handling characteristics yielding increased plant operating efficiency; and, 

• Possible reduced mortality of impinged organisms returned to the source waterbody. 

While there is considerable practical experience with HydroloxTM screens at water diversions for 

irrigation, there is relatively little practical experience to address these potential advantages at 

cooling water intake structures. While laboratory studies have demonstrated that impingement 

mortality can be high, these controlled studies do not address the range of species and 

environmental conditions typically found at cooling water intake structures. 

In the summer of 2007, National Grid and Intralox installed a HydroloxTM intake screen at the 

E.F. Barrett Generating Station to test full-scale performance. This report presents the results 

of an impingement survival study that was conducted at this screen from October 2007 through 

June 2008. Data from this study was used to estimate the survival rate of those fish species 

impinged on the Hydrolox screen during the study period. In addition, survival of fish impinged 

on a conventional traveling water screen located at the same unit was studied for comparison 

purposes. This study was jointly funded by National Grid and Intralox. 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

2 Facility Description

2. FACILITY DESCRIPTION 

E. F. Barrett Power Station is a steam-electric generating facility that is owned and operated by 

National Grid. The Station is located at Island Park, Long Island, New York in Hempstead Bay, 

approximately 2.5 miles inland of the southern Long Island coast and about 20 miles east of 

New York City (Figure 1). The Station consists of two steam-electric units which utilize a noncontact, once-through cooling water system. Units 1 and 2 began operation in 1956 and 1963, 

respectively. Each unit has a design capacity of 181 MW and a design flow of 228 cfs (102,000 

gpm). 

This study was conducted at Barrett Unit 2. This unit is protected by trash racks, a curtain wall, 

and coarse screens and has two intake bays about 14.0 ft wide with an invert of El. -12.5 ft (all 

elevations in this report are based on the plant datum in which 0.0 ft is equal to the mean low 

water level). A curtain wall, located at the face of each screenbay extends down to El. -1.0 ft 

providing an 11.5 ft opening for water to enter the intake. The trash racks, which are used to 

prevent large debris from entering the intake and damaging the circulating water pumps, are 

located about 2 ft downstream of the intake. In addition to the trash racks and coarse water 

screens, each intake bay has a traveling water screen located about 24 ft downstream from the 

bar rack. 

For this study, a single Hydrolox Screen with fish protection features was installed in one of the 

two intake forebays at Barrett Unit 2. This screen consists of a continuous strand of Hydrolox 

engineered polymer screen material (Figure 2a). The screen material is comprised of brick laid 

engineered polymer modules connected together at the hinges by polymer rods. This screen 

material is designed to operate over multiple head sprockets and a stationary shoe located in 

the foot section of a steel frame. A steel frame supports the head shaft, motor, and the screen 

components. 

Fish handling scoops similar to modified Ristroph buckets are attached to the base of each 

screen frame (Figure 2b). These scoops are designed to hold water and provide a relatively 

turbulence free zone that minimizes injuries to the impinged aquatic life. When the screen is 

operated, the scoops are lifted out of the water flow with the captured aquatic organisms. As 

the screen travels over the head sprockets, a low pressure spray header gently washes the 

organisms from the scoops and deposits them into a fish trough for return to the source 

waterbody (Figure 2c). Above the deck of the intake structure, the screen housing is angled 

backward to facilitate gentle removal of the aquatic life from the fish scoops into the fish trough. 

After that, a high pressure spray header directed from behind the screen cleans the remaining 

debris as the screen descends downwards along the return path. This debris is washed into a 

separate debris trough. 

The other intake forebay retained the existing conventional traveling water screen, which 

incorporates screen panels of 1/4 x 1 inch vertical opening, smooth-tex mesh. Fish and debris 

are removed from this conventional screen by a high-pressure front spraywash and returned to 

the source water body via a combined fish and debris sluice. Both screens were operated 

continuously during the impingement survival sampling. 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

3 Sampling Methods

3. SAMPLING METHODS 

For this study, the impingement collection systems at Barrett Unit 2 were modified to insure all the 

fish impinged were retained in adequate water to minimize collection stress. This collection 

system consisted of three devices. First, an aluminum collection basket with 5/16-inch mesh 

drains was inserted into the fish sluice of the Hydrolox screen. Second, a custom-fitted soft net 

with 1⁄4-inch mesh was inserted into the Hydrolox debris sluice. This net had a frame that locked 

into the sluice as it transitioned from the stainless sluice to the concrete below deck sluice. Third, 

the standard fish collection basket at the conventional screen was modified with an aluminum 

insert to hold 4 inches of water. 

Sampling was generally conducted weekly unless plant operations or lack of fish precluded 

collections. On each sampling date, both intake traveling screens were operated continuously. 

Sampling focused on an eight hour period from about 8:00 pm to 4:00 am as this was 

demonstrated to be the period of highest impingement rates based on earlier monitoring studies. 

Prior to each collection, all the sluices were checked for debris buildup and cleaned as 

necessary. The Hydrolox fish sluice collection basket was then installed first and the Hydrolox 

debris sluice net was installed next. At least 2 minutes later, the basket for the conventional 

screen was installed. This order was important as it started at the most upstream point and 

continued downstream in the screen washwater system. 

Each collection device was checked on an hourly or shorter interval and all fish collected were 

carefully removed and classified into one of three initial mortality categories: live, stunned, or 

dead. All live and stunned fish were then placed in the 5-gallon holding containers that were then 

placed in the 350-gal water trough of the latent effects monitoring facility. This holding facility was 

supplied with a continuous flow of water from the wash water header at the unit 2 intake. 

All specimens retained in this holding facility were maintained in separate holding containers by 

collection interval and multiple containers were used to minimize the potential for predation. All 

retained fish were checked at the completion of 24 and 48 hours after collection to determine 

condition (live, stunned1

, and dead) and all dead fish were removed at each check. All dead fish 

and all fish remaining at the end of the test period were identified to species, counted, and 

measured. In addition, water quality parameters (water temperature, salinity, dissolved oxygen, 

and ammonia) were monitored at each check to ensure adequate holding conditions. 

 

1

 For the purposes of calculating impingement survival at each time interval, any fish classified as stunned at that time 

were included with those dead. However, is some cases, these stunned fish recovered resulting in higher estimates of 

survival in subsequent time periods. 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

4 Results and Discussion

4. RESULTS AND DISCUSSION 

Generally, impingement survival sampling was conducted at Barrett whenever the Unit 2 cooling 

water pump behind each screen type was operating. As a result, impingement survival sampling 

was conducted using the Hydrolox screen on 27 dates over the period 20 October 2007 through 

16 June 2008 (Table 1). Survival sampling from the conventional screen was conducted on 16 

dates over the period 19 November 2007 through 21 April 2008. Over this period, mean water 

temperatures ranged from a low of 3.0 °C in January to more than 22 °C in mid-June. At the 

same time, mean dissolved oxygen concentrations ranged from 4.9 mg/l in late October to more 

than 10 mg/l during January and February. On all dates, dissolved oxygen concentrations were 

sufficiently high so as to not adversely affect impingement survival. Conductivity exhibited little 

variation across the study period. 

A total of 3,697 fish spanning 33 species were collected during the course of this study; 2,956 

from the Hydrolox screen fish sluice and 741 from the conventional screen (Table 2). No fish 

were collected from the Hydrolox debris sluice demonstrating the success of the Hydrolox screen 

system in separating impinged fish from debris. Most of the fish collected were relatively small 

(<150 mm Total Length (TL)) and likely less than one year old. All but 31 of those collected (1 

percent) were held for extended survival study. Survival results for all species and each screen 

type are presented in Table A-1. Nineteen of the 29 species collected from the Hydrolox screen 

and 16 of 19 species collected from the conventional screen consisted of a total of less than 20 

individuals. Data for these species is considered insufficient for reliable estimates of speciesspecific impingement survival. 

More than 20 individuals for each of ten different species were collected from the Hydrolox screen 

(Table 3). Of these ten species, five (seaboard goby, striped killifish, grubby, tautog and winter 

flounder) exhibited 100 percent survival when impinged on the Hydrolox screen. An additional 

two species (mummichog and northern pipefish) exhibited close to complete survival (> 98 

percent). Atlantic menhaden, a relatively delicate species, exhibited relatively low impingement 

survival (< 7 percent) whereas Atlantic silversides and American sand lance exhibited 

intermediate survival, about 60 and 71 percent, respectively. While numbers of the other species 

collected were insufficient to reliably estimate species-specific survival rates, the fact that 90 of 

the 91 individuals held for 48 hours survived suggest that survival of fish impinged on the 

Hydrolox screen should be high for most of these other species collected. The only mortality was 

a bay anchovy, a species known to be susceptible to impingement stresses. 

Among those three species for which reliable estimates of impingement survival could be 

calculated for both the Hydrolox and conventional screens, survival was substantially and 

significantly higher for the Hydrolox screen for Atlantic silverside (60.3 percent vs. 7.5 percent) 

while slightly higher although not statistically higher for mummichog and Atlantic menhaden (99.4 

percent vs. 96.4 percent and 6.8 percent vs. 0 percent, respectively) (Table 3). 

Most of the individuals of the ten species with sufficient catch to warrant estimation of 

impingement survival were collected from December through March (Figure 3), the period of 

primary impingement at Barrett (ASA 2005). The sole exception to this pattern was northern 

pipefish, which were collected principally in March and April. The seasonal patterns for those 

collected from the Hydrolox screen and from the conventional screen were similar. 

For Atlantic menhaden, grubby, and tautog, most of those collected were juveniles, less than 10 

cm long and likely less than a year old (Figure 4). For winter flounder, most were juveniles 

between 10 and 20 cm long and likely less than 15 months old. The remaining six species are all 

relatively small prey species and those impinged were likely to include a mix of juveniles and 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

5 Results and Discussion

adults. The length frequency distributions were similar for those collected from the Hydrolox 

screen and from the conventional screen. 

The results of this study demonstrate that survival of fish impinged on the Hydrolox screen at 

Barrett was generally near the upper bound of estimates reported in other studies and 

consistently equal to or greater than that found on the conventional traveling screen, albeit that 

such comparisons could be made for only a few species. Relatively low survival was only 

observed for Atlantic menhaden, a species known to be highly susceptible to stress-related 

mortality. However, even for this delicate species, survival from the Hydrolox screen was higher 

than that observed on the conventional screen. With the exception of bay anchovy, another 

known delicate species, no other individuals died after 48-hours of being impinged on the 

Hydrolox screen. These results suggest that impingement survival for these other species should 

also be high and possibly comparable to that observed for the more abundance species. This 

study included a suite of fish species commonly impinged at cooling water intakes located in 

coastal areas of the Northeast. 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

6 Results and Discussion

Table 1 Dates of impingement survival collections and coincident water quality measurements at 

the E.F. Barrett Generating Station, Oct 2007 – Jun 2007. 

Screen Tested Mean Water Quality 

Sample 

Date Hydrolox 

Screen 

Conventional 

Screen 

Water 

Temperature 

(C) 

Dissolved

Oxygen 

(mg/l) 

Mean 

Conductivity

(μS/cm) 

10/30/2007 √ 14.7 4.9 45640 

11/6/2007 √ 12.5 6.0 44800 

11/13/2007 √ 10.3 7.3 44370 

11/19/2007 √ √ 9.0 8.0 46500 

11/26/2007 √ √ 9.1 8.3 45600 

12/3/2007 √ √ 5.4 9.7 44170 

12/10/2007 √ 6.1 8.8 45320 

12/17/2007 √ √ 3.7 9.8 43030 

12/26/2007 √ √ 5.9 8.9 39140 

1/2/2008 √ 4.7 10.4 43770 

1/7/2008 √ √ 4.5 8.5 45880 

1/14/2008 √ √ 6.2 10.3 43770 

1/21/2008 √ √ 3.0 9.6 45450 

1/28/2008 √ √ 3.4 8.8 31850 

2/4/2008 √ √ 5.0 9.6 44540 

2/18/2008 √ 5.3 10.2 40390 

2/25/2008 √ 5.1 10.0 42650 

3/3/2008 √ 5.9 9.8 43250 

3/10/2008 √ 6.0 9.7 43420 

3/17/2008 √ √ 6.5 9.4 44420 

3/24/2008 √ √ 6.7 8.6 43800 

3/31/2008 √ 8.5 8.2 39720 

4/7/2008 √ √ 9.1 7.9 42220 

4/14/2008 √ √ 11.8 7.5 41670 

4/21/2008 √ √ 14.2 5.9 41200 

4/28/2008 √ 14.7 6.7 41760 

6/9/2008 √ 22.5 6.5 43220 

6/16/2008 √ 22.7 6.8 43420 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

7 Results and Discussion

Table 2 Numbers and length ranges of fish collected in impingement survival monitoring at the 

E.F. Barrett Generating Station, Oct 2007 – Jun 2007. 

Hydrolox Screen Conventional Screen 

Common name Number 

Collected

Length Range 

(TL mm) 

Number 

Collected

Length Range 

(TL mm) 

Atlantic silverside 1,605 49-123 531 47-119 

Mummichog 546 34-97 101 42-84 

Atlantic menhaden 195 40-112 45 52-349 

Northern pipefish 122 73-213 2 131-148 

Seaboard goby 115 38-61 16 34-60 

Striped killifish 90 41-100 14 46-92 

Grubby 59 54-109 1 78 

American sand lance 41 102-165 

Tautog 39 46-205 5 56-171 

Winter flounder 39 48-287 

Spotted hake 18 63-87 5 63-103 

Threespine stickleback 16 37-63 

Windowpane 12 29-61 3 49-57 

Lined seahorse 11 61-98 5 72-134 

Sheepshead minnow 8 36-51 4 25-43 

Northern searobin 7 45-421 

Rock gunnel 6 66-153 

Striped searobin 6 57-112 

Cunner 4 52-81 

Gulf Stream flounder 3 45-53 1 41 

Red hake 3 61-251 

Bay anchovy 2 66-80 

Bluefish 2 28-30 

Oyster toadfish 2 52-168 

Butterfish 1 192 

Northern stargazer 1 25 

Striped cusk-eel 1 86 

Weakfish 1 170 1 188 

White perch 1 105 1 115 

Alewife 1 125 

Atlantic croaker 1 45 

Black sea bass 3 42-61 

Feather blenny 1 64 

Total 2,956 741 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

8 Results and Discussion

Table 2 Estimates of extended (48-hour) impingement survival for the ten most abundant species 

collected in impingement survival monitoring at the E.F. Barrett Generating Station, Oct 2007 – 

Jun 2007. 

Hydrolox Screen Conventional Screen 

Species 

Estimated 

Impingement 

Survival 

95 Percent 

Confidence 

Bounds2

Estimated 

Impingement 

Survival 

95 Percent 

Confidence 

Bounds2

Atlantic silverside 60.3 57.9-62.7 7.5 5.5-10.0 

Mummichog 99.4 98.6-99.9 96.4 89.0-99.4 

Atlantic menhaden 6.8 3.9-11.0 0 0.0-8.4 

Northern pipefish 98.3 94.8-99.7 --3 

Seaboard goby 100 97.4-100.0 --3 

Striped killifish 100 96.6-100.0 --3 

Grubby 100 95.4-100.0 --3 

American sand lance 70.7 56.0-82.9 --3 

Tautog 100 92.6-100.0 --3 

Winter flounder 100 92.2-100.0 --3 

 

2

 95 percent exact confidence interval using Bayesian methods 

(http://www.causascientia.org/math_stat/ProportionCI.html). 

3

 Less than 20 individuals collected hence no survival calculated. 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

9 Results and Discussion

Figure 1 Characteristics of the HydroloxTM screen installed at the Barrett Generating Station, 

2007. 

a) b) 

c) 

Screen 

Low-pressure 

wash High-pressure 

wash 

Debris sluice 

Fish sluice 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OC

10 R

Nov Dec Jan Feb Mar Apr May 

05

1015

0

1020304050

0

1020304050

0

1020304050

0

1020304050

Winter flounder

Tautog

American sand lance

Grubby

 Hydrolox  Conventio

Striped killifish

Nov Dec Jan Feb Mar Apr May Jun

0

20406080

100

0

20406080

100

0

1020304050

0

100200

0

100200300

Seaboard goby

Northern pipefish

Atlantic menhaden

Mummichog

 Hydrolox screen Conventional screen

Atlantic silverside

Figure 2 Seasonal distribution of the most abundant species collected in impingement survival sampling at Barre

2008. 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OC

11 R

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 

0

20406080

 Length (cm)

0

20406080

0

20406080

0

20406080

0

20406080

Winter flounder

Tautog

American sand lance

Grubby

 Hydrolox s Conventio

Striped killifish

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

0

20406080

 Length (cm)

0

20406080

0

20406080

0

20406080

0

20406080

Seaboard goby

Northern pipefish

Atlantic menhaden

Mummichog

 Hydrolox screen Conventional screen

Atlantic silverside

Figure 3 Length frequency distributions of the most abundant species collected in impingement survival sampling – Jun 2008.
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

12 Literature Cited

5. LITERATURE CITED 

ASA 2005. E.F. Barrett Power Station Entrainment and Impingement Monitoring February 2003 

– February 2004. Prepared for KeySpan Energy. 
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

13 Appendix A

APPENDIX A
BARRETT IMPINGEMENT SURVIVAL MONITORING, OCTOBER 2007 - JUNE 2008

14 Appendix A

Table A-1 Results of impingement survival monitoring at the E.F. Barrett Generating Station, Oct 

2006 – Jun 2008. 

 Hydrolox Screen Conventional Screen 

 Initial After 48-hours Initial After 48-hours 

Common name Alive Dead Total Alive Dead Total Alive Dead Total Alive Dead Total

Atlantic silverside 1,538 67 1,605 968 637 1,605 373 158 531 39 481 520

Mummichog 544 2 546 542 3 545 100 1 101 53 2 55

Atlantic menhaden 177 18 195 13 178 191 4 41 45 0 33 33

Northern pipefish 122 0 122 118 2 120 2 0 2 2 0 2

Seaboard goby 115 0 115 113 0 113 15 1 16 5 7 12

Striped killifish 90 0 90 86 0 86 14 0 14 6 0 6

Grubby 59 0 59 59 0 59 1 0 1 1 0 1

American sand lance 41 0 41 29 12 41 0 0

Tautog 39 0 39 38 0 38 5 0 5 5 0 5

Winter flounder 39 0 39 36 0 36 0 0

Spotted hake 18 0 18 18 0 18 5 0 5 3 0 3

Threespine stickleback 16 0 16 16 0 16 0 0

Windowpane 12 0 12 12 0 12 3 0 3 3 0 3

Lined seahorse 11 0 11 10 0 10 5 0 5 4 0 4

Sheepshead minnow 8 0 8 8 0 8 4 0 4 3 0 3

Northern searobin 7 0 7 7 0 7 0 0

Rock gunnel 6 0 6 6 0 6 0 0

Striped searobin 6 0 6 0 0 0

Cunner 4 0 4 4 0 4 0 0

Gulf Stream flounder 3 0 3 3 0 3 1 0 1 1 0 1

Red hake 3 0 3 3 0 3 0 0

Bay anchovy 0 2 2 0 1 1 0 0

Bluefish 2 0 2 0 0 0

Butterfish 1 0 1 1 0 1 0 0

Northern stargazer 1 0 1 0 0 0

Oyster toadfish 1 0 1 0 0 0

Striped cusk-eel 1 0 1 1 0 1 0 0

Weakfish 1 0 1 0 1 0 1 0

White perch 1 0 1 1 0 1 1 0 1 1 0 1

Alewife 0 0 0 1 1 0

Atlantic croaker 0 0 0 1 1 0 1 1

Black sea bass 0 0 3 0 3 3 0 3

Feather blenny 0 0 1 0 1 0

Total 2,866 89 2,955 2,092 833 2,925 538 203 741 129 524 653