Impingement Monitoring at Manchester Street Station 2005 

Prepared for 

Dominion Energy Manchester Street, Inc. 

Providence, Rhode Island 

by 

Normandeau Associates, Inc. 

Falmouth, Massachusetts 

March 28, 2006 
Table of Contents

 Page

Summary 1 

Introduction 1 

Methods 2 

Results 

 Fish 

 Annual Impingement 5 

 High vs Low-pressure Collections 11 

 Multi-year Impingement Comparisons 12 

 Impingement rates vs flow and temperature 13 

Invertebrates 16 

Literature Cited 17 

Appendix 

Figures

 Page

 1. Schematic of the Providence River showing Manchester Street Station and 

 approximate location of high and low-pressure screen-wash return lines. 4 

 2. Percent of total for numerically dominant species of fish impinged on the 

 Manchester Street intake screens, 2005. 5 

 3. Estimated monthly impingement totals for Atlantic menhaden Atlantic herring, 

 winter flounder, Atlantic silverside, white perch, cunner, tautog, and total fish, 

 Manchester Street Station, 2005. Solid lines indicate the percent of total taken 

 each month for 1992, 1993, 1996-2004 pooled. 22-23 

 4. Length-frequency data for Atlantic menhaden (a), winter flounder January-April (b), 

 May-August (c), and September-December (d) impinged on the Manchester 

 Street intake screens, 2005. 24 

 5. Length-frequency data for Atlantic herring (a), silver hake (b), white perch (c), 

 and Atlantic tomcod (d) impinged on the Manchester Street intake screens, 2005. 25 
Figures (continued) 

 Page

 6. Percent of the annual total collected in high and low-pressure fish return lines 

 for numerically dominant fish plus "all others", 2005. 27 

 7. Percent of total number of fish impinged at Manchester Street Station which 

 were found in the low-pressure return line for selected numerically dominant 

 fish, 1996-2005. 27 

 8. Percent of total collected in the Manchester Street Station low-pressure return 

 line by month for Atlantic menhaden (top) and Atlantic silverside, 2005. Bars 

 indicate percent by month for pooled collections from 1995-2004. 28 

 

 9. Percent of total collected in the Manchester Street Station low-pressure return 

 line by month for winter flounder (top) and tautog, 2005. Bars 

 indicate percent by month for pooled collections from 1995-2004. 29 

10. Estimated annual totals for 19 species of fish plus total fish impinged on the 

 Manchester Street intake screens, 1975-2005 (1980, 1994, 1995 excluded, 

 see text). The geometric mean over the 1975-1993, 1996-2004 time series 

 is shown by a horizontal line in each case. 30-34 

11. Relationship between numbers of fish impinged (loge) and flow (top) and 

 water temperature, all species combined, Manchester Street Station, 2005. 35 

12. Relationship between numbers of fish impinged (loge) and station intake 

 flow (top) and numbers of fish impinged (loge) and water temperature, all 

 species combined, Manchester Street Station, 1992-2005. 36 

13. Comparison of loge annual number impinged at Manchester Street Station 

 and Brayton Point Station, Atlantic menhaden and weakfish, 1975-2005. 37 

14. Annual totals for four numerically dominant species of macroinvertebrates, 

 Manchester Street intake screens, 1992, 1993, 1996-2005. 38 
 Normandeau Associates, Inc.

 Tables

 Page

 1. Total estimated numbers impinged by species, Manchester Street Station, 

 2005. Standard scores for 2005, comparable totals for 1992 through 2004 

 as well as the long-term mean (1975-1993, 1996-2004) are also shown 

 (see footnotes). 39 

 2. Estimated numbers of fish impinged on the Manchester Street intake 

 screens by species and month, January-December 2005. 40 

 3. Mean numbers of fish impinged per million gallons of through-plant 

 flow, Manchester Street Station, January-December 2005. 41 

 4. Total estimated monthly catch for numerically dominant finfish and 

 ‘all others’ partitioned by low and high-pressure wash systems, 

 Manchester Street Station, January-December 2005. 42 

 5. Estimated numbers of fish impinged on the Manchester Street Station 

 revolving screens January-December by species, 1975-2005 (1980 

 excluded). 43-47 

 6. Correlation coefficients between numbers of fish (all species) impinged 

 at Manchester Street Station in 24-hour periods, water temperature 

 and intake flow, 1992-2005. 48-49 

 7. Estimated numbers of invertebrates impinged on the Manchester Street 

 intake screens by species and month, 1992-2005. New screen and wash 

 system installed October 1994-mid-July 1995. No data available for 

 that period. 50-56 

 Appendix

 1. Hydrographic and operational data recorded at Manchester Street Station 

 January-December 2005. 
 Normandeau Associates, Inc.

1

Summary

 Impingement sampling at Manchester Street Station in 2005 covered the tenth full year of 

station operation since the facility was repowered and the intake screens and wash system were 

modified to include low-pressure sprays, Ristroph screens, and a fish-return system. Collections 

were completed weekly year-round, each sample consisting of one 24-hour continuous 

screenwash period. A total of 46 species was represented in the year’s catch. Atlantic 

menhaden, Atlantic herring, winter flounder, and Atlantic silverside accounted for 98% of the 

number of fish impinged. Numbers of fish collected in the high and low-pressure return systems 

were enumerated separately to examine system efficiency. Consistent with 1995 through 2004

results, collections clearly showed that the majority of impinged fish were returned to the 

Providence River via the low-pressure wash system and were therefore not subjected to the highpressure sprays required to effectively remove impinged debris. 

 The overall 2005 total of 409,247 impinged fish, ranked fourth over the 29-year time 

series. The 2005 totals for impinged Atlantic herring and winter flounder ranked first, and 

Atlantic menhaden fourth over the 29-year. Pooling data for the 1995-2005 time-period 

suggested that 48% of the variation in numbers impinged could be explained by water 

temperature. Clearly, the major variations in numbers impinged remain unexplained and may 

perhaps be attributed to random and non-random movements of individual fish and fish schools 

coupled with natural seasonality and variation in population size. Collections of macroinvertebrates at Manchester Street in 2005 were dominated by seven-spine bay shrimp (n = 

5,695) and blue crab (n = 883). Annual totals for these species have been highly variable over 

the twelve complete sampling years. 

Introduction

 Impingement sampling at Manchester Street Station has been conducted since 1975 with 

the exception of 1980 when an impingement survival study was completed. Currently 

impingement sampling represents one phase of a biological monitoring program, which includes 

phytoplankton, periphyton, zooplankton, and ichthyoplankton sampling as required by RIPDES 

Permit No. RI0000434. The expanded study program resulted from the repowering of 

Manchester Street Station, which was completed in 1995. During the October 1994 through 

mid-July 1995 period the intake screens were replaced with new, continuously-operating 

Ristroph-type screens including high and low-pressure wash systems with separate return lines. 

The low-pressure return line, consisting of 12-inch reinforced fiberglass pipe, transports fish 

from the screen house to the hurricane barrier entrance. The high-pressure wash line traverses 

the intake channel to return impinged organisms to the river above the hurricane barrier. 

 This report summarizes results of finfish and macro-invertebrate sampling from January 

through December 2005, the tenth complete year with the new intake screen system. Where 

appropriate, attention is focused on the Representative Important Species (RIS) covered in the 

316 Demonstration for the repowering project (NEC and NEP 1990) including conversion to 

equivalent adults in cases where young fish were impinged. The RIS are listed below. 
2 

 Normandeau Associates, Inc.

Alewife/blueback herring Atlantic silverside 

 Atlantic menhaden Striped bass 

 Atlantic herring Black sea bass 

 Bay anchovy Weakfish 

 Rainbow smelt Tautog 

 Silver hake Winter flounder 

 Mummichog 

Methods

 Impingement sampling was conducted following the regime begun in April 19921. One 

24-hour collection was completed weekly by directing high and low-pressure wash waters 

(Figure 1) to separate 4 ft x 4 ft partially submerged holding pens. The intake system consists of 

five circulating water pumps each with trash racks and a traveling screen in front. Any time a 

pump is in operation, its traveling screen operates continuously. After a minimum of 24 hours 

the pens were hauled and the catch processed. On rare occasions (July 11 and July 18 for 

example), during periods of high impingement, the 24-hour sampling interval was shortened to 

increase survival. 

 All fish were identified to the lowest taxon possible, counted, and measured to the nearest 

millimeter in total length (TL). With large collections a minimum of 25 individuals was 

measured. Invertebrates large enough to be regularly impinged on the 3/8-inch intake screens 

were also identified and counted. Numbers of fish and invertebrates impinged per 24 hours were 

determined from the sampling interval, an extrapolated total then being obtained for the week by 

multiplying by seven. Estimated weekly totals were summed to provide monthly and annual 

totals. Hours of operation for each circulating water pump were obtained from the station log 

and used to estimate numbers impinged per million gallons (MG) of water circulated by the 

plant. 

 Where appropriate for representative important species, numbers of young fish were 

converted to older individuals using survival values obtained from the literature, the equivalent 

adult (EA) procedure. This allowed potential impingement losses to be equated to marketable 

and/or spawning-age fish which in turn can be compared with landings or spawning stock 

biomass where those data are available. Adjustments were made where possible to account for 

impingement survival. Assessment of that variable was completed at Manchester Street in early 

1997 (MRI 1997). Since numbers of fish potentially lost to impingement were relatively low 

following the EA procedure, no effort was made to compare them with landings or stock size 

data in this report. Impingement losses are assessed in conjunction with entrainment losses in 

the Ichthyoplankton Entrainment Monitoring at Manchester Street report (see MRI 2006). 

 

1

Prior to April 1992, collections were made by alternately rotating one or two of the five screens at one time through 

a complete revolution and removing any impinged fish by hand from the front face of the screens. Screens were 

typically washed every eight hours, the weekly sampling generally occurring 3-4 hours after a 0700 wash 
 Normandeau Associates, Inc.

3

 Before and after each 24-hour impingement sampling period hydrographic measurements 

were taken in the Manchester Street intake using either a YSI 600XL or Hydrolab Surveyor III. 

Measurements taken at the surface and 3-ft depth intervals to bottom included water temperature 

(±0.1 C), salinity (±0.1 ‰), pH (±0.1), and dissolved oxygen (±0.1 mg/l). 

 Hydrographic instruments were calibrated weekly using standard buffer solutions of pH 

7.0, and 10.0 for pH, a KCl solution of 0.42 N for conductivity, and the atmosphere for dissolved 

oxygen. Although factory set, temperature was checked with a certified thermometer and the 

data adjusted as required. 
 Normandeau Associates, Inc.

5

Results

Fish

Annual Impingement

 

 A total of 46 fish species were recorded in the 2005 Manchester Street Station 

impingement collections. Atlantic menhaden (Brevoortia tyrannus), Atlantic herring (Clupea 

harengus), winter flounder (Pseudopleuronectes americanus), and Atlantic silverside (Menidia

menidia) accounted for 47, 42, 7 and 2%, respectively, of the number of fish impinged (Figure 

2). There were two occasions when sample times for low-pressure wash collections were less 

than 24 hours due to the Providence River being frozen. When the river was frozen, the 

impingement collection pen could not be set at the end of the low-pressure pipe since a boat is 

required to access that point. As an alternative sampling method a small net was placed in the 

low-pressure fish return sluiceway inside the screen house. The net could only be set for short 

periods of time ranging from 8 to 20 hours to prevent the net from clogging with debris, blocking 

the sluiceway, and overflowing. 

 

Manchester Street Screens

Fish Impingement 2005

Atlantic Menhaden 47.5%

Atlantic Herring 41.8%

Winter Flounder 7.3%

Atlantic Silverside 1.5%

42 Remaining species 2.0%

Figure 2. Percent of total for numerically dominant species of fish impinged on the Manchester Street 

intake screens, 2005 
6 

 Normandeau Associates, Inc.

 Atlantic menhaden dominated the 2005 catch with an estimated annual impingement total 

of 194,189 fish (Table 1). They were collected in January, February and August through 

November (Figure 3, Table 2). In October alone 54% of the annual total of menhaden was 

impinged, yielding an impingement rate of 141 fish per hour, which is equivalent to 627 fish per 

million gallons of through-plant flow (Table 3). Over the year, total lengths ranged from 38 to 

300 mm with a mean of 67 mm [standard error (s.e.) = 1.49, n = 411; Figure 4a]. Individuals 

less than 100 mm in length, representing 93% of the total, were assumed to be young-of-theyear; those greater than or equal to 100 and less than 190, representing 5%, were assumed to be 

age 1, and those greater than 190 were assumed to age 2 +, accounting for 2%. 

 Numbers of young menhaden impinged were converted to equivalent age 2 fish, the age 

at which they enter the Narragansett Bay fishery (Durbin et al. 1983). The Atlantic States 

Marine Fisheries Commission (ASMFC 2004) provided an estimated annual instantaneous 

natural mortality rate (M) of 4.3 for young-of-the-year or age 0 fish and 0.98 for age 1 fish. Since 

the age 0 fish were impinged at various times during the year M = 4.3 was divided by 12 to 

estimate a monthly mortality rate. The monthly rate was applied for the number of months 

remaining between the time a young fish was impinged and its next birthday, which was 

assumed to be June 1. Assuming no fishing mortality (F) prior to age 2 so that Z or total 

instantaneous mortality = M, the natural mortality rate, an annual survival rate of 37.5% (s = e-z) 

was applied to the equivalent age 1 impingement total plus any age 1 fish impinged to estimate 

numbers of age 2 fish. Results of the post-impingement survival study (MRI 1997) confirmed the 

well-known fact that menhaden are impingement sensitive (see for example Tatham et al. 1978), 

an average of only 1.9% surviving 48-hour holding periods at Manchester Street Station. With 

such a low survival rate no further adjustment was made to the numbers impinged. The potential 

loss of an estimated 180,965 age 0, and 9,457 age 1 menhaden in 2005 plus the 3,779 age 2+ fish 

impinged would be equivalent to the loss of 6.650 age 2 fish to the local fishery. Assuming a 

weight of 0.6 pound for age 2 fish (ASMFC 2004), 6,650 menhaden would weigh 3,990 pounds. 

 Atlantic herring, with an estimated annual impingement total of 170,912 fish, ranked 

second in 2005 (Table 1). They were only present in collections in January and from June 

through August, with the July catch of 128,390 accounting for 75% of the annual total (Figure 3, 

Table 2). In 1996, 1998, 2000 and 2004, when herring were also abundant, they were similarly 

impinged during the late spring and summer. That pattern is consistent with their life history in 

that young fish resulting from late summer and autumn spawning on offshore banks form large 

aggregations in coastal waters the following spring and summer (Overholtz 2000). Total lengths 

in 2005 ranged from 53 to 207 mm with a mean of 90 mm (s.e. = 1.29, n = 135, Figure 4b). 

Atlantic herring spawn inshore and offshore in the spring, summer, or fall (see for example 

Bigelow and Schroeder 1953, Clayton et al. 1978, Collette and Klein-MacPhee 2002) so it can be 

difficult to assign young fish to year classes or cohorts based solely on total length. Individuals 

less than 100 mm impinged primarily in July 2005 were assumed to be age 0 fish surviving from 

fall spawning in 2004. Those between 100 and 200 mm impinged during the summer were 

likely age 1 fish from summer and autumn 2004. Since herring enter the fishery as sardines at 

age 1 and 50% of the stock matures at age 3 (Anthony and Waring 1980, Fogarty and Clark 

1983, NOAA 1998), the numbers impinged were converted to these two age classes. A natural 

mortality rate of 18.1% per year (instantaneous mortality rate, M = 0.20, NOAA 1998, Overholtz 

2000) was used. All impinged herring were assumed to have died upon return to the river based 
 Normandeau Associates, Inc.

7

on an overall impingement survival rate of only 4% (n = 26, MRI 1997). Based on these figures 

the estimated loss of herring to impingement in 2005 would be equivalent to the loss of 106,830 

age 1 fish. Applying an annual survival rate of 0.819 to the young fish resulted in an estimated 

equivalent loss of 71,601 age 3 adult fish. 

 Winter flounder ranked third with an annual estimated impingement total of 29,942 fish, 

accounting for 7% of the year’s fish total. While flounder were impinged throughout the year, 

numbers were greatest in March (18,495 fish) accounting for 62% of the species’ total (Figure 3, 

Table 2). Pooling results from past seasons indicated that January, February, and July normally 

showed the greatest winter flounder impingement (Figure 3). Following length-at-age data from 

Howell et al. (1992), Gibson (1993a), and Witherell and Burnett (1993) along with young-of-theyear length data from beach seine length frequencies in Mount Hope Bay and its tributaries 

(Dominion Energy Brayton Point LLC 2005, PG&E Generating and MRI 1999), the vast 

majority of fish were immature (Figure 4). In March, when flounder were most numerous in 

impingement collections, age 0 fish, those less than 160 mm, dominated the collections. A few 

age 1 fish, members of the 2003 year class, ranging from about 160 to 260 mm TL, were also 

taken from January to April. Partitioning the year’s catch into age classes based on length, 67% 

of the total was classified as age 0, 30% as age 1, and 3% age 2 (Figure 4). 

 Results of the post-impingement survival study (MRI 1997) indicated that latent youngof-the-year winter flounder survival is 95% among individuals returned to the river via the lowpressure system, 92% among those subjected to the high-pressure system. Only 10% of the 

flounder collected during the survival study were age 1 and 2 fish (n = 54); while sample size 

was small, a 100% latent survival rate was recorded. Conservatively applying survival rates of 95 

and 92% to all flounder estimated to have been returned to the river by the low (13,774) and 

high-pressure systems (16,149), respectively, provided an estimated 2005 loss of 1,981 fish. 

 Annual survival rates for winter flounder of 0.054% for age 0, 0.2996% for age 1, and 

0.4035% for age 2 were applied to the impingement totals to estimate the equivalent number of 

adult fish (age 3) potentially lost to the local population. Age 3 corresponds to the age at which 

both 50% of the population reaches reproductive maturity and recruitment to the fishery occurs 

(Gibson 1989a; NOAA 1998). Survival rates for age 0, 1 and 2 individuals were derived by 

averaging values reported by Gibson (1993b) and Rose et al. (1996). Since annual survival rates 

are for the entire life stage, assuming an April 1 birthday, survival rates were generated for each 

month. All age 0 fish were aged to their first April birthday using monthly survival data and 

then annual rates were applied for all fish until age 3. Based on these data, the 2005 

impingement total adjusted for impingement survival would be equivalent to 636 age 3 fish. 

 Atlantic silversides ranked third over the year as a whole with an estimated annual 

impingement total of 6,145 fish in 2005 accounting for 2 % of the annual total. Individuals were 

impinged in all months except April thru July, with the February catch (4,135 fish) accounting 

for 67% of the year’s total (Figure 3). Two length frequencies (January–June and JulyDecember)were generated to determine what year classes were represented in the catch. Total 

length-frequency data indicated that silversides taken in 2005 were primarily members of the 

2004 year class (Conover 1979; Figure 6a, 6b). Young-of-the-year fish under 50-mm total 

length are rarely impinged but, because they fit through the intake screens, are susceptible to 
8 

 Normandeau Associates, Inc.

entrainment. Results from the impingement survival study completed at Manchester Street (MRI 

1997) suggested that latent survival rates of 28% and 17% were obtained for the low-pressure 

and high-pressure return lines, respectively. These data assume no sub-lethal impingement 

effects occurred after fish returned to the river, such as increased loss from predation or declines 

in feeding and growth rates leading to greater overall mortality rates. 

 Atlantic silversides mature at age 1 and spawn from late April through June (Conover and 

Kynard 1984). Over the course of their first (and typically only) winter, mortality can reach 99% 

(Conover 1979). Many of those remaining in the spring die during the spawning season (Bayliff 

1950, Conover and Ross 1982). Based on these data equivalent adults resulting from 

impingement losses were calculated as follows: Half the fish collected during January and 

February was assumed to survive to the beginning of the April 1 spawning season had 

impingement not occurred. All fish impinged from March through August were assumed to be 

adults and fish impinged from September through December were assumed to survive late fall 

and winter at a rate of 25%. These rates are considered conservative particularly for the small 

number of adults that survive until the fall of their second year since they are unlikely to survive 

to spawn a second time. These assumed rates were applied to the number impinged each month 

after adjusting for impingement survival. Applying these survival rates to the 3,624 silversides 

returned via the low-pressure line and 2,519 returned via the high-pressure line would reduce the 

potential estimated 2005 losses to 2,352 equivalent adult fish. 

 Ten species from the RIS list were not among the numerical dominants in the 2004 

impingement collections. These included silver hake, (Merluccius bilinearis) tautog (Tautoga 

onitis), alewife (Alosa pseudoharengus), weakfish (Cynoscion regalis), mummichog (Fundulus 

heteroclitus), rainbow smelt (Osmerus mordax), black sea bass (Centropristis striata), blueback 

herring (Alosa aestivalis), striped bass (Morone saxatilis), and bay anchovy (Anchoa mitchilli). 

Each of these species except bay anchovy was represented in the 2005 collections although there 

were only 13 mummichogs, six rainbow smelt, three black sea bass, one blueback herring and 

one striped bass collected. These fish provided estimated annual impingement totals of 104, 39, 

20, 8 and 7, respectively. The rainbow smelt ranged between 101 and 120 mm and were 

impinged in December. The black sea bass were young-of-the-year ranging between 77 and 110 

mm and were sampled in November and December. The single striped bass impinged in 

December was 358 mm suggesting it was an age 3 fish (see for example Setzler et al. 1980). 

 Silver hake were impinged from January through March and in December producing an 

estimated annual impingement total of 1,536 fish. They were impinged primarily in February 

(1,323 fish; Table 2). Individuals ranged from 67 to 140 mm in length with a mean of 101 mm 

(s.e. = 1.72, n = 76). Referring to information provided by Almeida (1987) and Helser (1996), 

fish around 100 mm TL impinged in winter were probably nearing the end of their first year. 

Silver hake between 100 and 150 mm were age 2 fish. Silver hake at age 2 enter the commercial 

fishery and 50% of those are mature (Almeida and Anderson 1978, NOAA 1998). Based on this, 

the number of juveniles potentially lost to impingement was converted to a number of equivalent 

age 2 fish. An annual survival rate of 0.67 obtained from Almeida and Anderson (1978) and 

Helser et al. (1996) produced an estimated loss of 1,223 age 2 fish. Since only five silver hake 

were taken during the impingement survival study and each one either died or was injured 
 Normandeau Associates, Inc.

9

following 48-hour holding periods, all impinged silver hake were assumed to have died shortly 

after being returned to the river. 

 Tautog were impinged throughout the year with an estimated annual impingement total of 

810 fish. The largest monthly collections were obtained in September and October with 169 and 

191 fish, respectively (Figure 3). Total length measurements indicated that fish ranged from 38 

to 280 mm with an average length of 125 mm (s.e. = 5.96, n = 111). Following Cooper (1967) 

who studied tautog from Rhode Island waters, individuals (male and female lengths averaged) 

reach 62 mm TL at age 1, 131 mm at age 2, 197 mm at age 3, 244 mm at age 4, and 287 mm at 

age 5. Based on Cooper’s data the numbers of tautog impinged at Manchester Street were 

assumed to be distributed as follows: age 0 - 14%, age 1 - 40%, age 2 - 36%, age 3 - 8%, age 4 - 

<1%, and age 5 - <1%. Tautog were not well represented during the impingement survival study 

completed in early 1997 (n = 12). Within that small sample, survival was 100% following 48-

hour holding periods suggesting they are relatively hardy. To be conservative, only half the 

tautog impinged was assumed to have survived once returned to the river. 

 Utilizing otter trawl age-frequency data from Cooper (1967) an annual survival rate of 

0.83527 was calculated for tautog for ages 5 through 22. Although Cooper presented data for 

ages 1 through 4, there is good evidence that these younger age classes are not as susceptible to 

capture as older fish. This is based on the size of younger fish relative to otter trawl mesh sizes 

and the greater movement observed among older fish in comparison to younger fish, which tend 

to remain near the home site (Olla et al. 1974). In the absence of more reliable data, the survival 

rate for ages 5-22 was applied to ages 1-4 as well. The estimated annual survival rate of 0.83527 

was applied in succession to each age group to estimate the number of age 3 and age 6 tautog 

which might have resulted had impingement losses not occurred. These ages were selected 

because tautog mature at about age 3 (Chenoweth 1963) and enter the sport fishery at about age 

6. These conversions result in a potential estimated loss of 249 age 3 or 181 age 6 fish. 

 Alewives were impinged in January, February, May, and August thru December with an 

estimated annual impingement total of 456 fish. Individuals impinged ranged from 50 to 169 

mm in length (mean = 107 mm, s.e. = 6.49, n = 29). Following Clayton et al. (1978), small 

alewives (less than 150 mm) impinged during this time would be age 0 fish. Young fish were 

equated to the number of reproductive age fish that might have survived had impingement not 

occurred. Estimates of annual survival rates between the time they migrate from natural river 

systems (age 0) and age 3 when they begin to return to spawn were obtained from data provided 

by Cole et al. (1978) and Gibson (1989b). The proportion of the number of age 3 fish returning 

to the Parker River system in Massachusetts in 1978 to the number of age 0 fish leaving the same 

system three years earlier was approximately 0.05. From these data, an annual survival rate of 

37% was obtained. Working with the Gilbert Stuart Brook alewife run in North Kingstown, 

Rhode Island, Gibson (1989b) estimated an annual survival rate of 38.2% for later year classes. 

Because the estimates based on Cole et al. (1978) and Gibson (1989b) were remarkably similar, 

these estimates were averaged (mean = 37.6%). This survival rate was applied successively 

beginning at age 1 for all fish collected to obtain an estimate of 79 age 3 alewives potentially lost 

to impingement effects during the year. Only nine river herring were collected during the 

impingement survival study and each of those individuals died during the holding period (MRI 
10 

 Normandeau Associates, Inc.

1997). Therefore alewives and blueback were assumed to experience 100% mortality as a result 

of impingement. 

 Weakfish had an estimated annual impingement total of 269 fish and were present from 

August to December (Table 2). Length-frequency data for 2005 indicated that all fish ranged 

from 65 to 235 mm in length with a mean of 163 mm (s.e. = 7.13, n = 39). Weakfish grow 

rapidly and all individuals were likely members of the 2004 and 2005 year classes (see for 

example Shepard and Grimes 1983, Szedlmayer et al. 1990, Lowerre-Barbieri et al. 1994, 

Lowerre-Barbieri et al. 1995). Gibson (1993c) reported that weakfish partially recruit to the 

fishery at age 1. Only two weakfish were collected during the impingement survival study 

completed at Manchester Street (both were dead when collected). Since they are soft-bodied, the 

species is likely to be impingement sensitive and all impinged in 2005 were assumed to have not 

survived. To be additionally conservative, had they not been impinged, it was assumed that 80% 

of the fish would have survived the winter to reach age 1 when they might have entered the 

fishery. Based on this information an estimated total of 11 fish could have been lost to the 

fishery based on 2005 impingement losses. 

Mummichogs ranged from 55 to 110 mm (mean = 76, s.e. = 7.5) suggesting they ranged 

from young-of-the-year to two-year-old fish (Fritz and Garside 1975, Valiela et al. 1977, Able 

1990). They were most abundant in April when 47% of the estimated annual total of 104 fish 

were impinged. Most mummichogs likely survive impingement at Manchester Street Station 

(93%, n = 29; MRI 1997). Individuals measuring less than 53 mm impinged during the winter 

were assumed to be age 0. Those between 55 and 70 mm impinged during spring were assumed 

to be age 1 and those greater than 100 mm impinged during late winter age 2. An annual 

survival rate of 0.46 was applied to age 1 fish (Meredith 1975 cited in Clayton et al. 1978). 

Following these guidelines and conservatively assuming an impingement survival rate of 75%, 

104 impinged mummichogs would equate to 23 age 2 equivalent adults. 

High vs Low-Pressure Collections

 When repowered, the Manchester Street Station intake screens were fitted with separate 

high and low-pressure fish removal and return systems to maximize impingement survival. The 

impingement survival study completed early in 1997 indicated that, in most cases, fish returned 

to the river via the low-pressure system had a higher probability of survival than those returned 

via the high- pressure system (MRI 1997). 

 Numbers of fish collected in the high and low-pressure return systems in 2005 were 

enumerated separately to examine system efficiency. Extrapolated totals by sampling location 

were examined on an annual basis for the 2005 numerical dominants and all others pooled 

(Figure 6, Table 4). Annual low-pressure return efficiency results are included for those species 

common enough during the ten complete years following repowering (1996-2005) to make 

comparisons (Figure 7). Percent removal by the low-pressure system was also examined on a 

monthly basis where possible for Atlantic herring, winter flounder, Atlantic silverside, tautog, 

and Atlantic menhaden. These species were collected often enough over the course of the year 

to provide at least three separate monthly values (Figures 8 and 9). For each of these species 
 Normandeau Associates, Inc.

11

collections were pooled from the 1995-2004 seasons to provide information on past results. Data 

from July through December 1995 were included since the new screen wash system was 

operational at that time. Monthly percentages based on estimated extrapolated totals of less than 

110 fish were omitted from these figures since those values represent small, actual sample sizes 

of less than 15 fish. 

 Consistent with the late half of July 1995 through 2004 results (MRI 2005), collections 

clearly showed that the majority of impinged fish were returned to the Providence River via the 

low-pressure wash system and were therefore not subjected to the high-pressure sprays required 

to effectively remove impinged debris (Figures 6, 7). Annual 2005 low-pressure return rates 

were highest for cunner (88%). The system was least efficient overall for silver hake (44%). For 

all other species, a combined rate of 71% was recorded. Comparing low-pressure efficiency for 

1996-2005, the ten complete years available, for species collected regularly the time series shows 

percentages to be generally consistent with a range between 55 and 97%. Eight exceptions were 

observed. The 1998 and 2005 values for menhaden (38 and 51%, respectively) appear low 

compared to 1996 to 2004 values, and the 1999 and 2001 values for northern pipefish, 

(Sygnathus fuscus; 34 and 30%, respectively) were low compared to its 1996-2004 efficiency 

percentages (2002 thru 2005 numbers of fish collected were too few to evaluate wash 

efficiency). The 2002, 2003 and 2004 values for Atlantic silverside (20, 30 and 47 %, 

respectively) appear to be low compared to the other 1996 to 2001 values. Lastly, the 2005 

values for winter flounder (46%) were lowest compared to the 1996 to 2004 values. No clear 

explanation is apparent for the lower than expected values although some previous collections 

have coincided with large numbers of leaves and trash with which these fish may have become 

entangled. Entanglement of fish in aquatic vegetation was believed to reduce low-pressure wash 

efficiency at the RESCO facility in Saugus, MA (MRI 1988). 

 The monthly low-pressure efficiency values, where sufficient numbers of fish were 

impinged, indicated that 2005 values were consistent with previous monthly estimates. 

Menhaden values for five months ranged from 16% (February) to 61% (October). Low-pressure 

efficiency values for menhaden appeared low relative to previous seasons (Figure 8). The low 

efficiency for February may be an anomaly due to the short sample times (4 hours) on the lowpressure side due to the Providence River being frozen (see methods). January and December 

were the only months that silversides had a greater than average (based on the pooled data set 

from 1995 – 2004) low-pressure return efficiency (99 and 76%, respectively) in 2005. Winter 

flounder values for ten months ranged from 15% (January) to 99% (August). April, July, August 

and October were the only months to have above average low-pressure return efficiency values 

in 2005 compared with the pooled data from 1995-2004 (Figure 9). Tautog were caught in 

sufficient numbers in September and October (92 and 100%, respectively) to assess the monthly 

low-pressure efficiency. Both values exceeded the pooled data set (Figure 9). 

 
12 

 Normandeau Associates, Inc.

Multi-year Impingement Comparisons

 The number of species represented in the catch in 2005 (46) ranked fifth out of 28 years 

and exceeded the long term mean of 32 species dating back to 19752

. Since repowering, there 

does not appear to be any apparent trends in RIS abundance. 

 Impingement totals by species for 2005 were compared with past data sets. Totals for 

2005 as well as 1992 through 2004 are tabulated together with the geometric mean for the 1975 

through 1993, 1996-2004 time series (Table 1). The 1992 through 2005 sample years are 

tabulated together because the sampling regime changed in 1992 (see Methods). Annual totals 

for 1975 through 2005 appear in Table 5 with the exception of 1980 when an impingement 

survival study replaced the regular abundance program. Although shown, totals for 1994 and 

1995 represent only a portion of the year because the screens were replaced between October 

1994 and mid-July 1995. Estimated annual impingement values for 19 selected species plus all 

species combined are presented in Figure 11 (1994 and 1995 were omitted here). The list of 19 

includes the typical numerical dominants plus any RIS which have been numerically important 

in past years regardless of their rank in 2005. To facilitate comparison of 2005 values with past 

years, standard normal scores or standard deviates (also referred to as Z scores) were computed 

for each species. Standard scores express the degree of departure from the long-term mean in 

terms of the standard deviation (see for example Zar 1974, Chase and Brown 1992, Sokal and 

Rohlf 1995). Since the 28 annual totals (1975-1993, 1996-2004, 1980 excluded) for any given 

species do not conform to the normal distribution in most cases because of occasional high 

values, totals were first log-transformed ln (x + 1). Spot checks (Ryan and Joiner 1976) 

confirmed that this procedure normalized each species' data set except for rarely encountered 

species, i.e. where many years contained zeros (Table 5); in these cases the standard scores are 

recognized as somewhat biased. 

 The annual impingement fish total for all species for 2005 was 409,247, ranking fourth 

over the 29-year time series (Figure 10). Reviewing individual species totals, those impinged in 

particularly high numbers in 2005 (positive standard scores) compared to past years included 

Atlantic menhaden, Atlantic herring, and winter flounder. The 2005 totals for Atlantic herring 

and winter flounder ranked first, and Atlantic menhaden fourth over the 29-years (Figure 11, 

Table 5). 

 Winter flounder’s annual impingement total of 29,942 fish ranked first and was 6.3 times 

the time series mean (4,779 fish, Figure 10). Since the winter flounder impinged were young 

fish, the high numbers suggest that the 2004 and 2005 year classes were relatively strong. 

 Mummichog were impinged in relatively low numbers in 2005 ranking 25th (104 fish, 

34% of their long term mean of 309 fish). American eel (Anguila rostrata) abundance on the 

screens have been declining since 1996 (Figure 10). 

 

2

 construction-shortened 1994 and 1995 seasons were excluded from the mean. 
 Normandeau Associates, Inc.

13

Impingement Rates vs Flow and Temperature

 For each year from 1992 to 2005 total numbers of fish impinged each week were 

compared with intake water temperature (mid-depth readings) and through-plant flow rates 

(Appendix Table 1) to determine if any relationship can be demonstrated among these variables. 

Both temperature and flow have been shown to influence fish impingement rates at other power 

station intake structures (see for example Grimes 1975, Lifton and Storr 1978, Turnpenny 1983, 

Harmon et al. 1999). That impingement might increase as water velocity increases through the 

screens is self-evident. At higher velocities fish are more likely to drift onto the screens and 

once there greater water pressure will make it more difficult to swim away. Impingement often 

increased with declining water temperatures, presumably as a direct result of declining metabolic 

activity. Fish also move to deeper water in winter to escape cold surface waters while intake 

velocity at the face of the screens often increases with depth because the pump intakes are 

located near bottom. 

 Since repowering in 1995, the water temperature and numbers of fish impinged were 

significantly correlated in only 4 out of the past 11 years. Numbers of fish were first logtransformed before Pearson correlation coefficients (r) were calculated. Since some annual data 

sets deviated from normality even following loge transformation, nonparametric Spearman’s 

Rank correlation coefficients (rs) were also calculated (Table 6). A statistically significant 

negative correlation with water temperature was found in 1992, 1993, and 1997. The 

relationship was strongest in 1992 before the intake screens were upgraded (r = -0.695, 

probability, p < 0.001). That season 48% of the variation in numbers impinged could be 

explained by water temperature. The inverse relationship between numbers impinged and water 

temperature during those years supports the postulate that fish are more susceptible to 

impingement during cold-water months when their metabolism, reaction time, and swimming 

ability are at a minimum. For some species overall condition may also be poorer during winter 

when less food is available. High impingement totals for January 2005 was consistent with the 

cold water pattern. 

 The 1998, 1999, and 2001 data sets contrasted with 1992, 1993, and 1997 in that numbers 

impinged and water temperature were positively correlated. The positive relationship between 

water temperature and numbers impinged during those years may be attributable to strong 

positive correlations between temperature and flow; r = 0.755, p = 0.001 in 1998, r = 0.426, p = 

0.002 in 1999, and r = 0.308, p = 0.026 in 2001. Highest mean monthly flow rates in 1998, 

1999, and 2001 occurred in July, August, and September, the warmest time of year. Variation in 

intake flow with season of the year reflects to some extent regional power requirements. In years 

preceding 1998 either no statistically significant correlation between flow and temperature 

(1994, 1996) was found or the relationship was inverse (1993, 1995, 1997), intake flow 

averaging higher during winter. It is also notable that juvenile Atlantic menhaden contributed a 

high percentage of the impingement catch from 1999 to 2005. These fish are most abundant 

inshore during summer and early fall when water temperatures are near their seasonal highs. 

 Statistically significant correlations with intake flow were observed in seven of the 

fourteen years examined - 1992, 1994, 1996, 1997, 1998, 1999 and 2001. In each case the 

relationship was positive suggesting that impingement increases with increasing flow. The 1994 
14 

 Normandeau Associates, Inc.

data set presented the strongest case (r = 0.596, p = 0.001), 36% of the variation in number 

impinged being explained by intake flow. In 2005 there was no apparent correlation between 

flow and loge fish (r = 0.228, p = 0.104). Since neither the log transformed number of fish 

impinged nor station flow were normally distributed, the straight correlation coefficient should 

be viewed with caution. As Figure 12 displays, four flow regimes predominated during the year, 

three of the four with a wide range of impingement rates. While the remaining data show little 

relationship over the range of flows at which the plant operated, the indication is that 

impingement drops off at low flow. 

Year 2002 proved to be only the third, with the exception of the short 1995 season and 

2000, in which neither water temperature (r = 0.240 p = 0.086) nor flow (r = -0.096, p = 0.499) 

were statistically correlated with numbers of fish impinged, inconsistent with previous years. The 

first time no correlation appeared was in 2000. The absence of a relationship with flow in 2000 

and 2002 was likely due, at least in part, to limited range in flow. Over the course of the 

respective years 69% and 48% of the impingement samples were collected under the same 

circulating water flow rate (10.8 million gallons per hour). Reasons for lack of correlation with 

temperature during those two years are not readily apparent but similar results were obtained in 

1994, 1996, and 2000 as well. 

 Data sets from 1995 through 2005 were pooled to encompass years following 

replacement of the intake screens with high and low pressure spray headers, Ristroph-type screen 

panels, and continuous operation. With the pooled data set numbers of fish impinged were 

positively correlated with water temperature (r = 0.110, p = 0.01; Figure 12). However, 

regression analysis indicated that only 2% of the variation in numbers impinged from 1995 - 

2005 could be explained by water temperature. The pooled data set 1995 to 2005 , like the 2005 

data, (Rs = 0.039, p = 0.364) was not normally distributed and the Spearman rank coefficients 

were not statistically significant. The amount of variation in the data is remarkable and reflected 

in the low correlation coefficients. 

 Results of the individual annual analyses as well as the multi-year view indicate that 

much of the variation in numbers of fish impinged remains unexplained. Likely other sources 

include random and non-random movements of individual fish and fish schools coupled with 

natural cycles of seasonal activity and variations in population size. Fish move in and out of the 

intake canal as they forage for food and likely encounter the intake screens as they do so. Other 

individuals no doubt encounter the face of the screens unintentionally as they seek to evade 

predators. The accumulation of debris on the trash racks at both the hurricane barrier and the 

intake itself, in spite of best efforts to minimize it, probably creates areas of increased flow, 

which can lead to additional impingement among individuals that would avoid design flow rates. 

In some locations strong winds associated with significant storm events have been associated 

with high rates of impingement (NUSCO 1987, NAI 1996). No wind effect has been noted at 

the Manchester Street intake, perhaps because it is well protected from all but southerly winds. 

 The large numbers of young-of-the-year menhaden impinged in late summer 1999 to 

2005 extending into the fall and winter of those years reflect to a certain extent the timing 

between the presence of strong year classes of fish susceptible to impingement and high seasonal 

intake flow rates. Menhaden travel in very dense schools and are often attracted both to intake 
 Normandeau Associates, Inc.

15

and discharge currents. Once the schools arrive, there appears to be a slight observable pattern to 

numbers impinged. Their abundance in recent years could account for the small amount of 

explained variation in numbers impinged within discrete years as well as the pooled data set. To 

explore this possibility further correlation coefficients were recalculated individually for 1999 

through 2005 after removing menhaden from the data sets. Somewhat surprisingly in each case, 

no relationship was apparent between numbers impinged and temperature or flow (Table 6). 

To explore the possible contribution of population size to numbers impinged total annual 

impingement at Manchester Street was compared with that at Brayton Point Station in the 

northeast corner of Narragansett Bay. Annual totals were available for Brayton Point for each 

year in which they were recorded at Manchester Street through 2004. If fish populations vary 

somewhat uniformly in upper Narragansett Bay in general rather then disproportionately 

between the east and west sections, then numbers impinged might be correlated between both 

power stations assuming no major changes in circulating water use patterns. Non-parametric 

Spearman rank correlation coefficients indicated that numbers impinged were correlated between 

location for Atlantic menhaden (rs = 0.575, p = 0.002), and weakfish (rs = 0.395, p = 0.046; 

Figure 14) but not for alewife (rs = -0.103, p = 0.618), blueback herring (rs = 0.383, p = 0.054), 

white perch (rs = -0.255, p = 0.509), tautog (rs = 0.146, p = 0.476), or winter flounder (rs = -

0.291, p = 0.149). These results suggest that east and west Narragansett Bay carry similar 

population signals for menhaden and weakfish, which are reflected in numbers impinged despite 

the great variation with flow rates. Both species are migratory, utilizing the Bay for spawning 

and nursery area, young-of-the-year accounting for the majority of fish impinged. The 

remaining species which appear to be impinged independently between east and west sides of the 

Bay consist of resident and anadromous species which likely consist of distinct subpopulations. 

Invertebrates

 Macroinvertebrates impinged on the Manchester Street intake screens in 2005 are 

tabulated by month in Table 7. For comparison monthly totals for 1992 through 2004 are 

included since they are the only years during which invertebrates were enumerated from 

impingement collections. Numerical dominants in 2005 included the seven-spine bay shrimp 

(Crangon septemspinosa – 5,695 animals), blue crabs (Callinectes sapidus – 883 animals), lady 

crab (Ovalipes ocellatus – 344 animals) and green crabs (Carcinus maenas – 277 animals). 

These four species accounted for 78, 12, 5 and 4%, respectively, of the year’s invertebrate total. 

Seven-spine bay shrimp were impinged only in March. The majority of the seven-spine bay 

shrimp (>99%) were removed by the low-pressure system. Blue crabs were impinged primarily 

in November. The majority of blue crabs (92%) were returned to the river via the low-pressure 

system in 2005. Lady crabs were sampled from October to December with 72% (254 crabs) 

captured in November. Lady crabs were removed from the screens primarily (91%) by the lowpressure system. Green crabs were sampled in June and from August to December. 

 Impingement of invertebrates has been highly variable over the twelve complete years 

and two incomplete years for which data are available (Figure 14). Blue crabs were uncommon 

in 1992 (37 total), 1993 (70) and 2004 (83), relatively abundant in 1996 (9,098) and 1998 
16 

 Normandeau Associates, Inc.

(8,117), and most abundant in 1999, 2000, and 2001 (15,384, 17,818, 15,110, respectively). 

Blue crab abundance increased in 2005 following three years of steady decline. Bay shrimp 

followed a similar pattern but declined after 1996 (42,708 animals) until 1998 (7,691 animals), 

and then increased in 1999 and 2000 (18,673 and 671,977, respectively). Bay shrimp, after being 

absent from the 2002 collections and relatively low in 2003 (282), were moderately abundant in 

2005 (5,695). Green crabs (Carcinus maenas) were absent from the 1992, 1993 and 2003 

collections, appeared in increasing numbers in the shortened 1994 (5 in 9 months) and 1995 

seasons (3,413 in 6 months), and were relatively abundant in 1997 (5,505) and 1998 (5,456). 

Since 1999, green crabs have not been abundant ranging from 12 in 2004 to 53 in 2000. Lady 

crab numbers varied with no apparent trend. 
 Normandeau Associates, Inc.

17

Literature Cited

Ahrenholz, D.W., W.R. Nelson, and S.P. Eperly. 1987. Population and fishery characteristics of 

Atlantic menhaden, Brevoortia tyrannus. Fishery Bulletin U.S. 85(3):569-600. 

Almeida, F.P. 1987. Stock definition of silver hake in the New England-Middle Atlantic area. 

North American Journal of Fisheries Management. 7(2):169-186 

 and E.D. Anderson. 1978. Status of the southern New England-Middle Atlantic silver hake 

stock - 1978. National Marine Fisheries Laboratory Reference 78-55. 19p. 

Anthony, V.C. and G.T. Waring. 1980. Estimates of herring spawning stock biomass and egg 

production for the Georges Bank-Gulf of Maine region. Northwest Atlantic Fisheries 

Organization. SCR Document 80/IX/135. 38p 

ASMFC (Atlantic States Marine Fisheries Commission). 2004. Atlantic Menhaden Stock 

Assessment Report for Peer Review. Stock Assessment Report No. 04-01 (Supplement) 

of the Atlantic States Marine Fisheries Commission. 160p. 

Bayliff, W.H. Jr. 1950. The life history of the silverside Menidia menidia (Linnaeus). 

Chesapeake Biological Laboratory Publication 90. 30p. 

Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine. Fishery Bulletin 74. 

577p. 

Chase, W. and F. Brown. 1992. General Statistics. Second Edition. John Wiley & Sons, Inc., 

New York. 645p + appendix. 

Chenoweth, S.B. 1963. Spawning and fecundity of the tautog, Tautoga onitis (Linnaeus). M.S. 

Thesis. Graduate School of Oceanography, University of Rhode Island, Kingston. 60p. 

Clayton, G., C. Cole, S. Murawski and J. Parrish. 1978. Common marine fishes of coastal 

Massachusetts. Massachusetts Cooperative Extension Service, Amherst, Mass. 231p. 

Cole, C.F, R.J. Essig, and O.R. Sarrelle. 1978. Biological investigation of the alewife 

population, Parker River, Massachusetts. Final Report (unpublished). National Marine 

Fisheries Service (P.L. 89-304). 

Collette and Klein-MacPhee 2002 

Conover, D.O. 1979. Density, growth, production and fecundity of the Atlantic silverside, 

Menidia menidia (Linnaeus), in a central New England estuary. M.S. Thesis, University 

of Massachusetts, Amherst. 59p. 
18 

 Normandeau Associates, Inc.

 and B.E. Kynard. 1984. Field and laboratory observations of spawning periodicity 

behavior of a northern population of the Atlantic silverside, Menidia menidia (Pisces: 

Atherinidae). Environmental Biology of Fishes 11(3):161-171. 

 and M.R. Ross. 1982. Patterns in seasonal abundance, growth and biomass of the Atlantic 

silverside, Menidia menidia, in a New England estuary. Estuaries 5(4):275-286. 

Cooper, R.A. 1967. Age and growth of the tautog, Tautoga onitis, from Rhode Island. 

Transactions of the American Fisheries Society 96:134-142. 

Dominion Energy Brayton Point LLC 2005 

Durbin, A.G., E.G. Durbin, T.J. Smayda, and P.G. Verity. 1983. Age, size, growth, and 

chemical composition of Atlantic menhaden, Brevoortia tyrannus, from Narragansett 

Bay, Rhode Island. Fisheries Bulletin U.S. 81(1):133-142. 

Fogarty, M.J. and S.H. Clark. 1983. Status of Atlantic herring resources in the Gulf of Maine 

region - 1983. National Marine Fisheries Service, Woods Hole Laboratory Reference 

Document No. 83-46. 33p. 

Fritz, E.S. and E.T. Garside. 1975. Comparison of age composition, growth, and fecundity 

between two populations each of Fundulus heteroclitus and F. diaphanus (Pisces: 

Cyprinodontidae). Canadian Journal of Zoology 53(4):361-369.. 

Gibson, M.R. 1989a. A study and comparison of winter flounder growth rates in several 

northeast Atlantic populations from New Jersey to Newfoundland with emphasis on 

Rhode Island. Rhode Island Division Fish and Wildlife. Res. Ref. Doc. 89/5. 

 1989b. Alewife restoration studies January 1, 1988 to December 31, 1988. R.I. Department 

of Environment Management, Division of Fish and Wildlife. Performance Report, 

Project No. F-26-R-23. 21p. 

 1993a. Stock assessment of winter flounder in Rhode Island, 1992: A report to the RI 

Marine Fisheries Council. Rhode Island Division Fish and Wildlife. Res. Ref. Doc. 

93/1. 

 1993b. Population dynamics of winter flounder in Mount Hope Bay in relation to 

operations at the Brayton Point electric plant. Rhode Island Division Fish and Wildlife. 

Unpublished. 

Grimes, C.B. 1975. Entrapment of fishes on intake water screens at a steam electric generating 

station. Chesapeake Science 16(3):172-177. 
 Normandeau Associates, Inc.

19

Harmon, P.L., D. Mathur, and R.M. Matty, Jr. 1999. Design of CWIS in accordance with fish 

swim speed measurements at Peach Bottom Atomic Power Station. In: Proceedings 

EPRI Power Generation Impacts on Aquatic Resources Conference, Atlanta, GA. 

Helser, T.E. 1996. Growth of silver hake within the U.S. continental shelf ecosystem of the 

northwest Atlantic Ocean. Journal of Fish Biology 48:1059-1073. 

 , E.M. Thunberg, and R.K. Mayo. 1996. An age-structured bioeconomic simulation of 

U.S. silver hake fisheries. North American Journal of Fisheries Management 16:783-

794. 

Howell, P., A. Howe, M. Gibson, and S. Ayvazian. 1992. Fishery management plan for inshore 

stocks of winter flounder, Pleuronectes americanus. Fishery Management Report No. 

21. Atlantic States Marine Fisheries Commission. 138p. 

Lifton, W.S. and J.F. Storr. 1978. The effect of environmental variables on fish impingement. 

p299-311 In Jensen, L.D. (ed.) Fourth National Workshop on Entrainment and 

Impingement. 5 December 1977 Hyatt Regency O'Hare Hotel, Chicago, Il. EA 

Communications, New York. 

Massachusetts Division of Marine Fisheries. 1999. Menhaden management changes coming. 

DMF News p8. 

MRI (Marine Research, Inc.). 1997. Post-impingement survival study Manchester Street Station 

January 1996-February 1997. Prepared for Narragansett Electric Company and New 

England Power Company April 1997. 

 . 1988. Saugus River Biological Monitoring Program Post-operational Summary Report, 

1986-1987. Prepared for Wehran Engineering, Middletown, NY. 

 . 2000. Impingement monitoring at Manchester Street Station 1999. Submitted to U S 

Gen New England, Inc.. 58p + appendix. 

_____. 2006. Ichthyoplankton Entrainment Monitoring at Manchester Street Station, 

Providence, Rhode Island, 2005. Prepared for Dominion Energy Manchester Street, Inc. 

Providence, Rhode Island 

NAI (Normandeau Associates, Inc.). 1996. Seabrook Station 1995 environmental studies in the 

Hampton-Seabrook area. A characterization of environmental conditions during the 

operation of Seabrook Station. Prepared for North Atlantic Energy Service Corporation. 

NEC and NEP (Narragansett Electric Company and New England Power Company). 1990. 

Section 316 Demonstration for the Manchester Street Station Repowering Project. 

Revised May 1990. 
20 

 Normandeau Associates, Inc.

NFSC (Northeast Fisheries Science Center). 1998. 27th Northeast regional stock assessment 

workshop (27th SAW). Northeast Fisheries Science Center Reference Document 98-15. 

NOAA (National Oceanic and Atmospheric Administration). 1998. Status of the fishery 

resources off the northeastern United States for 1998. NOAA Technical Memorandum 

NMFS-NE-115. 149p. 

NUSCO (Northeast Utilities Service Company). 1987. Winter flounder studies. In: Monitoring 

the marine environment of Long Island Sound at Millstone Nuclear Power Station, 

Waterford, Connecticut. Summary of studies prior to Unit 3 operation. 151p. 

Olla, B.L., A.J. Bejda and A.D. Martin. 1974. Daily activity, movements, feeding and seasonal 

occurrence in the tautog, Tautoga onitis. Fisheries Bulletin U.S. 72(1):27-35. 

Overholtz, W. 2000. Atlantic herring - survey status. National Marine Fisheries Service. 

PG&E Generating and Marine Research Inc.(MRI). 1999. Brayton Point Station. 1998 annual 

biological and hydrological report. 

Rose, K.A., J.A. Tyler, R.C. Chambers, G. Klein-MacPhee, and D.J. Danila. 1996. Simulating 

winter flounder population dynamics using coupled individual-based young-of-the-year 

and age-structured adult models. Canadian Journal of Fisheries and Aquatic Sciences 

53(5):1071-1091. 

Ryan, T.A. Jr. and B.L. Joiner. 1976. Normal probability plots and tests for normality. The 

Pennsylvania State University Statistics Department. 19p. Unpublished. 

Setzler, E.M., W.R. Boynton, K.V. Wood, H.H. Zion, L. Lubbers, N.K. Mountford, P. Frere, L. 

Tucker, and J.A. Mihursky. 1980. Synopsis of biological data on striped bass, Morone 

saxatilis (Walbaum). U.S. Department of Commerce. NOAA Technical Report NMFS 

Circular 433. 

Sokal, R.R. and F.J. Rohlf. 1995. Biometry. Third Edition. W.H. Freeman and Company, New 

York. 887p. 

Tatham, T.R., D.L. Thomas, and G.J. Miller. 1978. Survival of fishes and macroinvertebrates 

impinged at Oyster Creek Generating Station. p235-243 In: Jensen, L.D. (Ed). Fourth 

National Workshop on Entrainment and Impingement. Chicago, IL. December 1977. 

Turnpenny, A.W.H. 1983. Multiple regression analysis for forecasting critical fish influxes at 

power station intakes. Journal of Applied Ecology 20:33-42. 

Witherell, D.B. and J. Burnett. 1993. Growth and maturation of winter flounder, Pleuronectes

americanus, in Massachusetts. Fishery Bulletin U.S. 91(4):816-820. 
 Normandeau Associates, Inc.

21

Zar, J.H. 1974. Biostatistical Analysis. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. 

620p. 
North Discharge

Diffuser Box

High Pressure Fish Return

Low Pressure Fish Return

Manchester 

Street Station

Intake 

gate

Intake Canal

Figure 1. Aerial photo of the Providence River showing Manchester Street Station and approximate location of high 

and low-pressure screen-wash return lines.
Figure 3. Estimated monthly impingement totals for Atlantic menhaden, Atlantic herring, Winter flounder, Atlantic silverside, silver hake, cunner, tautog, and total fis

2005. Solid lines indicate the percent of total taken each month for 1992, 1993, 1996-2004 pooled.

Atlantic Menhaden (RIS)

Monthly Estimated Impingement Totals

, , , , ,,, ,

,

,

, ,

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

1

10

100

1,000

10,000

100,000

1,000,000

Number of Fish

010203040506070

Percent Of Total

2005 1992-2004 ,

Atlantic Herring (Monthly Estimated Impingeme

' ' ' 

'

'

'

'

' 

Jan Feb Mar Apr May Jun Jul Aug S

10

100

1,000

10,000

100,000

1,000,000

2005 1992-2004 '

Winter Flounder (RIS)

Monthly Estimated Impingement Totals

,

,

,

,

,

,

,

,

,

, , ,

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

10

100

1,000

10,000

100,000

Numbers of Fish

051015202530

Percent Of Total

2005 1992-2004 ,

Atlantic Silverside 

Monthly Estimated Impingemen

&

& & & & & & & 

Jan Feb Mar Apr May Jun Jul Aug S

1

10

100

1,000

10,000

Numbers of Fish

2005 1992-2004 &
Figure 3. (continued). 

Silver Hake

Monthly Estimated Impingement Totals

'

'

'

'

' ' '

'

' ' '

'

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

10

100

1,000

10,000

010203040

Percent Of Total

2005 1992-2004 '

Cunner

Monthly Estimated Impingemen

,

,

,

,

,

,

,

,

,

Jan Feb Mar Apr May Jun Jul Aug Se

0

4080

120160200240280320360400440480520560600

Numbers Of Fish

2005 1992-2004 ,

Tautog (RIS)

Monthly Estimated Impingement Totals

,

,

,

,

,

,

,

,

,

,

,

,

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

0

50

100150200250300

Numbers Of Fish

051015202530

Percent Of Total

2005 1992-2004 ,

Total Fish

Monthly Estimated Impingemen

,

, , , , , ,

,

Jan Feb Mar Apr May Jun Jul Aug S

100

1,000

10,000

100,000

1,000,000

Number of Fish

2005 1992-2004 ,
Figure 4. Length-frequency data for Atlantic menhaden (a), winter flounder January-April (b), May-August (c), September-Dece

Manchester Street intake screens, 2005.

(d) (c)

(a) (b)

Atlantic Menhaden

Length Frequency

January - December 2005

Manchester Street Screen

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

270

280

290

300

Length Class (mm)

05

101520253035

Percent of Total

Mean = 62(s.e.= 1.49)

n = 411

Winter Flound

Length Frequenc

January - April 20

Manchester Street Screens

30

50

70

90

110

130

150

170

190

210

230

2

Length Class (mm)

05

10152025

Percent of Total

Mea

Winter Flounder

Length Frequency

May - August 2005

Manchester Street Screens

30

50

70

90

110

130

150

170

190

210

230

250

270

290

310

330

Length Class (mm)

05

101520

Percent of Total

Mean = 106 (s.e. = 2.97)

n = 106

Winter Flound

Length Frequenc

September - Decembe

Manchester Street Screens

30

50

70

90

110

130

150

170

190

210

230

Length Class (mm)

05

10152025

Percent of Total

Mea
Figure 5. Length-frequency data for Atlantic silverside January-June (a), July-December (b), Atlantic herring (c), Silver hake (d) im

Street intake screens, 2005.

(d) (c)

(a) (b)

Atlantic Silverside

Length Frequency

January - June 2005

Manchester Street Screens

30 40 50 60 70 80 90 100 110 120 130 140

Length Class (mm)

05

101520253035

Percent of Total

Mean = 84 (s.e.= 1.42)

n = 111

Atlantic Silvers

Length Frequenc

July - December 20

Manchester Street Screens

30 40 50 60 70 80 90 100 110 120 13

Length Class (mm)

0

102030405060

Percent of Total

Mea

Atlantic Herring

Length Frequency

January - December 2005

Manchester Street Screens

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

Length Class (mm)

0

10203040

Percent of Total

Mean = 90 (s.e.= 1.59)

n = 135

Silver Hake

Length Frequenc

January - December 

Manchester Street Screens

30

40

50

60

70

80

90

100

110

Length Class (mm)

05

1015202530

Percent of Total

Me
Figure 7. Percent of total number of fish collected at Manchester Street Station which were found

 in the low pressure return line for selected numerically dominant fish, 1996-2005.

Figure 6. Percent of the annual total collected in high and low-pressure return lines for 

 numerically dominant fish plus "all others", 2005.

Manchester Street Station - 2005

Fish Return System Efficiency

Atlantic Menhaden

Winter Flounder

Atlantic Silverside

Atlantic Herring

Cunner

Tautog

White Perch

Silver Hake

Atlantic Tomcod

All Others

0

20

40

60

80

100

Percent Of Total

HP LP

Manchester Street Station

Low Pressure Efficiency

Atlantic Herring

Winter Flounder

Atlantic Silverside

Tautog

Atlantic Menhaden

Atlantic Tomcod

Northern Pipefish

Cunner

0

20

40

60

80

100

Percent of Total

High/Low 2005
Figure 8. Percent of total collected in the Manchester Street Station low pressure return

 line by month for Atlantic menhaden (top) and Atlantic silverside 2005. Bars

 indicate percent by month for pooled collections from 1995-2004.

Atlantic Menhaden - 2005

Low Pressure Return Efficiency

,

,

,

,

,

,

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

0

20

40

60

80

100

Percent Of Total

, 2005 1995-2004

Atlantic Silverside - 2005

Low Pressure Return Efficiency

,

,

,

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

0

20

40

60

80

100

120

Percent Of Total

, 2005 1995-2004
Figure 9. Percent of total collected in the Manchester Street Station low pressure return lines

 by month for winter flounder (top) and tautog 2005. Bars indicate percent by month 

 percent by month for pooled collections from 1995-2004.

Winter Flounder - 2005

Low Pressure Return Efficiency

,

,

, ,

,

,

,

,

,

,

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

0

20

40

60

80

100

120

Percent Of Total

, 2005 1995-2004

Tautog - 2005

Low Pressure Return Efficiency

,

,

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

0

20

40

60

80

100

Percent Of Total

, 2005 1995-2004
Figure 10. Estimated annual totals for 19 species of fish plus total fish impinged on the Manchester Street intake screens, 1975-2005 (1980, 1994, 1995 exclud

mean over the 1975-2004 times series is shown by a horizontal lin in each case.

Alewife (RIS)

Manchester Street Intake Screens

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

0

300600900

1,2001,5001,8002,1002,4002,7003,0003,3003,600

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

 American Eel 

Manchester Street Intake 

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

Year

0

200400600800

1,0001,2001,4001,600

Number of Fish

Annual Total 1975-1993,1996-2004 G

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

1

10

100

1,000

10,000

100,000

1,000,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

Year

10

100

1,000

10,000

100,000

1,000,000

10,000,000

100,000,000

Number of Fish

Annual Total 1975-1993,1996-2004 Ge
Figure 10. (continued).

Atlantic Silversides (RIS)

Manchester Street Intake Screens

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

10

100

1,000

10,000

100,000

1,000,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

Atlantic Tomco

Manchester Street Intake 

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

19

Year

0

400800

1,2001,6002,0002,4002,8003,200

Number of Fish

Annual Total 1975-1993,1996-2004 Geom

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

0

200400600800

1,0001,2001,4001,600

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1

Year

1

10

100

1,000

10,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geom
Figure 10. (continued).

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

0

500

1,0001,5002,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1

Year

10

100

1,000

10,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geom

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

10

100

1,000

10,000

100,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

19

Year

0

200400600800

1,0001,200

Number of Fish

Annual Total 1975-1993,1996-2004 Geom
Figure 10. (continued).

Silver Hake (RIS)

Manchester Street Intake Screens

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

100

1,000

10,000

100,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1

Year

10

100

1,000

10,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geom

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

0

400800

1,2001,6002,0002,4002,8003,200

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

Weakfish (RIS)

Manchester Street Intake 

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

19

Year

0

400800

1,2001,6002,0002,4002,800

Number of Fish

Annual Total 1975-1993,1996-2004 Geom
Figure 10. (continued).

White Perch

Manchester Street Intake Screens

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

1

10

100

1,000

10,000

Number of Fish

Annual Total 1975-1993,1996-2004 Geometric Mean

Windowpane

Manchester Street Intake 

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

Year

0

500

1,0001,5002,000

Number of Fish

Annual Total 1975-1993,1996-2004 G

Winter Flounder (RIS)

Manchester Street Intake Screens

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

Year

05

10152025

Number of Fish (Thousands)

Annual Total 1975-1993,1996-2004 Geometric Mean

1975

1976

1977

1978

1979

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

Year

1,000

10,000

100,000

1,000,000

10,000,000

100,000,000

Annual Total 1975-1993,1996-2004 G
Figure 11. Relationship between numbers of fish impinged (loge) and flow (top) and water

 temperature, all species combined, Manchester Street Station, 2005.

Manchester Street Station

Fish Impingement vs. Intake Flow - 2005

,

,

,,

, ,

,

,

,

,

,

,,

,

,

,

,

,

, ,

,

,

, ,

,

,

,

,

,

,

,

, ,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

2 4 6 8 10 12 14

Station Flow (MG/Hr)

0

2.1

4.2

6.3

8.4

Loge Total Fish Per 24 Hours

Rs = 0.228

p = 0.104

Manchester Street Station

Fish Impingement vs. Water Temperature - 2005

,

, , ,

, , ,

, ,

,

,

, ,

,

,

,

,

, ,

,

,

, , ,

,

,

,

,

,

,

, ,

,

,

,

,

,

, ,

,

, ,

,

,

,

,

,

,

,

,

1 6 11 16 21

Water Temperature (C)

0

2

4

6

8

10

Loge Total Fish Per 24 Hours

Rs = -0.137

p = 0.346
Figure 12. Relationship between numbers of fish impinged (loge) and flow (top) and water

 temperature, all species combined, Manchester Street Station, 1992-2005.

Manchester Street Station

Fish Impingement vs. Water Temperature - 1995 - 2005

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!!

!

!!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!!

!

!

!

!

!

!

!

!

!

!

!

!

!

0 5 10 15 20 25 30

Water Temperature (C)

0

2

4

6

8

10

12

14

16

Loge Total Fish Per 24 Hours

Rs = 0.039, p = 0.364

Manchester Street Station

Fish Impingement vs. Intake Flow - 1995 - 2005

!

!

!

!

!!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!!

!!

!!

!

!

!

!

!

!

!

!!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

2 4 6 8 10 12 14 16 18 20 22 24

Station Flow (MG/Hr)

0

2

4

6

8

10

12

14

16

Loge Total Fish Per 24 Hours

Rs = -0.010, p = 0.809
Figure 13. Comparison of loge annual number impinged at Manchester Street Station and

Brayton Point Station, Atlantic menhaden and weakfish, 1975-2005.

Atlantic Menhaden Impingement

Manchester Street vs Brayton Point

,

,

,

,

,

,

,

,

,

,,

,

,

,,

,,

,

,

,

, ,,

,

,

,

,

,

2 4 6 8 10 12 14 16 18

Manchester Street (loge)

0

2

4

6

8

10

12

14

Brayton Point (loge)

(rs = 0.594, p < 0.05)

Weakfish Impingement

Manchester Street vs Brayton Point

,

,

,

,

, ,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

,

0 2 4 6 8 10

Manchester Street (loge)

0

2

4

6

8

Brayton Point (loge)

(rs = 0.404, p > 0.05)
Figure 14. Annual totals for four numerically dominant species of macroinvertebrates, Manchester Street intake screens, 1992, 1993

Blue Crab

Manchester Street Intake Screens

Screens were not sampled from October 1994 through June 1995

37

298

70

662

9,098

770

8,117

15,38417,81815,109

1,333

297

83

883

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

1

10

100

1,000

10,000

100,000

Seven-spine Bay S

Manchester Street Intake Sc

Screens were not sampled from October 1994 through June 1995

90

5

183

2,799

42,708

17,126

7,691

18,673

671,997

2

1992 1993 1994 1995 1996 1997 1998 1999 2000 2

1

10

100

1,000

10,000

100,000

1,000,000

Green Crab

Manchester Street Intake Screens

Screens were not sampled from October 1994 through June 1995

5

3,413

1,954

5,5055,456

655

53 57

22

12

277

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

1

10

100

1,000

10,000

Lady Crab

Manchester Street Intake Sc

Screens were not sampled from October 1994 through June 1995

4,654

37 42

24,121

61,098

1,689

393 405

21

3

1992 1993 1994 1995 1996 1997 1998 1999 2000 2

10

100

1,000

10,000

100,000
Species 2005 2005 Z Score 2004 2003 2002 2001 2000 1999 1998 1997 1996 1993 

Atlantic menhaden 194,189 0.8887 56,889 56,968 11,642,543 884,212 130,042 9,808,927 979 5,527 71,643 247 15Atlantic herring 170,912 1.9900 29,570 4,157 39 499 24,026 22,667 66,150 1,565 10,708 0 Winter flounder 29,942 1.8538 15,997 11,283 8,850 14,622 3,948 9,716 5,902 13,398 15,360 1,935 1Atlantic silverside 6,145 0.1074 768 5,086 242,786 3,875 1,096 7,317 1,970 58,036 30,712 804 3Silver hake 1,536 0.2717 10,129 27,305 178 626 115 1,421 911 536 154 212 Atlantic tomcod 1,292 0.8357 2,033 696 639 1,178 388 412 896 500 3,087 39 Cunner 1,267 1.1987 821 404 4,192 2,420 674 1,942 756 358 610 0 Tautog 810 0.5852 891 895 1,993 1,449 337 753 1,295 2,075 465 92 White perch 638 0.5274 3,991 3,744 313 2,908 754 2,348 270 6,537 749 2,896 Alewife 456 0.2181 439 406 70 2,601 343 107 102 128 134 0 Weakfish 269 0.4741 0 0 135 246 40 327 2,732 2,451 60 0 Bluegill 186 0.1791 55 266 85 228 94 92 2,118 46 597 0 Bluefish 182 0.9207 0 20 10 7 7 10,454 0 0 17 0 Grubby 169 1.3544 45 39 14 243 13 574 147 314 223 12 Windowpane 151 -0.2052 129 34 0 959 127 119 191 1110 591 38 Oyster toadfish 132 1.2952 272 660 455 419 88 77 67 45 0 0 Mummichog 104 -0.4402 42 164 154 293 144 7 289 605 691 326 Striped searobin 90 0.6464 28 464 38 6,024 76 53 30 19 0 43 Threespine stickleback 88 -0.3185 416 346 110 749 1,703 398 212 800 545 136 Smallmouth flounder 60 1.1675 21 49 35 21 35 159 52 62 109 21 Largemouth bass 58 2.2718 7 7 38 9 0 29 6 0 28 0 Northern pipefish 57 -0.7392 59 7 90 114 176 998 831 719 495 110 American eel 54 -1.6076 134 143 257 174 288 555 559 757 1,364 51 Hogchoker 45 0.1998 65 192 281 41 12 196 238 51 184 12 Butterfish 41 0.2031 7 51 26 70 20 42 99 250 14 0 Rainbow smelt 39 0.7724 13 47 0 42 0 6 24 39 56 0 American shad 38 1.9536 7 0 0 7 0 6 6060Golden shiner 38 3.4407 0 15 0 7 7 0 0 0 26 0 Gizzard shad 34 2.6800 7 51 0 0 50 7 0000Striped killifish 34 -0.2947 7 121 306 101 13 47 26 42 113 37 Summer flounder 31 0.9448 45 26 148 0 7 84 19 40 17 0 Black crappie 24 1.4123 6 7 0 7 0 53 69 070Black sea bass 20 0.8366 6 149 105 3,221 0 6 6 0 42 0 Little skate 15 -0.4686 7 438 0 41 116 41 44 124 418 13 Scup 14 0.4215 68 350 13 56 21 75 62 13 0 0 Yellow perch 11 0 0 0 0 0 0 0000Atlantic cod 10 5.5613 0 0 0 0 0 7 0000Blueback herring 8 -1.4203 339 154 7 13 33 71 578 80 34 0 Crevalle jack 8 0.3958 0 20 0 0 10 96 0 19 0 0 Lookdown 8 2.5751 0 7 0 0 0 0 0 25 0 0 Common carp 7 2.3792 0 0 0 0 0 0 0000Conger eel 7 1.7865 0 0 0 19 0 16 0000Fourspot flounder 7 0.5959 7 7 0 0 38 11 6 0 0 0 Lumpfish 7 0.3897 0 0 7 259 0 37 0 305 0 0 Pumpkinseed 7 1.2441 0 7 0 0 0 7 0 0 22 0 Striped bass 7 0.7021 0 0 34 7 11 8 7 35 15 0 Total 409,247 123,320 114,778 11,903,917 927,760 164,841 9,870,253 87,642 96,576 139,259 7,024 16Grand Total 409,247 123,382 115,619 11,904,170 928,257 165,192 9,870,753 88,014 96,849 139,479 7,151 16

Table 1. Total estimated numbers impinged by species, Manchester Street Station, 2005. Standard scores for 2005, comparable totals for 1992 throas the long-term mean (1975-1993, 1996-2004 are also shown (see footnotes).

* Due to repowering upgrades, sampling in 1994 was only possible through September. Sampling in 1995 began in mid-July once new equipment became functional. These two included in calculation of the time series means.Grand total includes fish taken in other years but were no listed because they were not taken in 2005. Refer to Table 5 for a complete listing.
Table 2. Estimated numbers of fish impinged on the Manchester Street intake screens by species and month, January-December 2005.

Species Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec Total

Alewife 26 14 0 0 19 0 0 7 21 8 6 355 456

American Eel 7 0 0 0 0 0 0 7 7 0 26 7 54

American Shad 0 7 0 0 0 0 0 0 0 0 24 7 38

Atlantic Cod 0 0 0 0 10 0 0 0 0 0 0 0 10

Atlantic Herring 21 0000 42,488 128,390 13 0 0 0 0 170,912

Atlantic Menhaden 36,900 6,034 0000 9 42,989 468 104,906 2,883 0 194,189

Atlantic Silverside 1,768 4,135 35 0 0 0 0 47 21 8 16 115 6,145

Atlantic Tomcod 153 35 106 138 85 15 47 540 20 0 19 134 1,292

Black Crappie 0 0 0 0 0 0 0 0 0 18 6 0 24

Black Sea Bass 0 0 0 0 0 0 0 0 0 0 6 14 20

Blueback Herring 0 0 0 8 0 0 0 00 0 0 0 8

Bluefish 0 0 0 0 0 168 0 0 7 0 0 7 182

Bluegill 0 0 0 82 6 13 0 0 0 49 36 0 186

Butterfish 7 0 0 0 0 0 0 21 0 0 6 7 41

Common Carp 0 0 0 0 0 0 0 00 7 0 0 7

Conger Eel 0 0 0 0 0 0 0 00 0 0 7 7

Crevalle Jack 0 0 0 0 0 0 0 00 0 8 0 8

Cunner 20 7 8 31 114 87 13 564 182 148 67 26 1,267

Fourspot Flounder 0 0 0 0 0 7 0 00 0 0 0 7

Gizzard Shad 21 7 0 0 0 0 0 0 0 6 0 0 34

Golden Shiner 0 0 0 38 0 0 0 0 0 0 0 0 38

Grubby 7 21 84 41 10 6 0 0 0 0 0 0 169

Hogchoker 0 0 0 0 0 0 18 0 20 7 0 0 45

Largemouth Bass 0 0 0 0 0 0 0 0 0 58 0 0 58

Little Skate 7 0 0 8 0 0 0 0 0 0 0 0 15

Lumpfish 0 7 0 0 0 0 0 00 0 0 0 7

Lookdown 0 0 0 0 0 0 0 00 0 8 0 8

Mummichog 0 0 7 49 0 9 7 10 0 0 8 14 104

Northern Pipefish 7 0 14 8 7 0 0 7 0 0 0 14 57

Oyster Toadfish 0 0 0 0 10 23 14 14 14 15 21 21 132

Pumpkinseed 0 0 0 0 0 0 0 00 7 0 0 7

Rainbow Smelt 26 7 6 0 0 0 0 0 0 0 0 0 39

Scup 0 0 0 0 0 0 0 14 0 0 0 0 14

Silver Hake 151 1,323 48 0 0 0 0 0 0 0 0 14 1,536

Smallmouth Flounder 39 0 0 0 0 0 0 0 0 0 0 21 60

Striped Bass 0 0 0 0 0 0 0 00 0 0 7 7

Striped Killifish 0 7 0 0 0 0 0 07 7 6 7 34

Striped Searobin 0 0 0 0 0 0 0 41 0 8 8 33 90

Summer Flounder 0 0 0 0 0 12 0 0 0 6 0 13 31

Tautog 20 47 49 26 38 31 9 87 169 191 71 72 810

Threespine Stickleback 0 48 40 0 0 0 0 0 0 0 0 0 88

Weakfish 0 0 0 0 0 0 0 22 21 19 102 105 269

White Perch 7 35 575 0 0 0 0 0 7 0 0 14 638

Windowpane 7 0 34 31 0 0 0 7 65 0 0 7 151

Winter Flounder 3,290 2,538 18,495 887 476 114 1,112 2,441 314 117 51 107 29,942

Yellow Perch 0 0 0 11 0 0 0 0 0 0 0 0 11

Total Fish 42,484 14,272 19,501 1,358 775 42,973 129,619 46,831 1,343 105,585 3,378 1,128 409,247

Number of Species 19 16 13 13 10 12 9 17 15 18 20 24 46
Table 3. Mean numbers of fish impinged per million gallons of through-plant flow, Manchester Street Station, January -December, 20

Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct NAtlantic Menhaden 266.7750 43.3299 0.0000 0.0000 0.0000 0.0000 0.0473 255.6805 2.8281 627.1177 17.2Atlantic Herring 0.1150 0.0000 0.0000 0.0000 0.0000 267.7883 780.1928 0.0768 0.0000 0.0000 0.0Winter Flounder 23.9413 41.0309 109.9073 5.2803 2.8075 0.6601 6.6245 14.2218 1.8802 0.6943 0.3Atlantic Silverside 5.5234 37.9303 0.2029 0.0000 0.0000 0.0000 0.0000 0.2746 0.1212 0.0445 0.0Silver Hake 0.9920 13.5641 0.2897 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Atlantic Tomcod 0.9364 0.2058 0.6201 0.8115 0.4985 0.1056 0.2776 3.1473 0.1191 0.0000 0.1Cunner 0.1392 0.0413 0.0424 0.1869 0.6698 0.4322 0.0748 3.2914 1.0734 0.8692 0.3Tautog 0.1150 0.3700 0.3032 0.1522 0.2224 0.1464 0.0473 0.5095 0.9981 1.1249 0.4White Perch 0.0383 0.2450 3.5404 0.0000 0.0000 0.0000 0.0000 0.0000 0.0405 0.0000 0.0Alewife 0.1533 0.1624 0.0000 0.0000 0.1108 0.0000 0.0000 0.0393 0.1214 0.0445 0.0Weakfish 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.1298 0.1200 0.1122 0.6Bluefish 0.0000 0.0000 0.0000 0.0000 0.0000 1.3675 0.0000 0.0000 0.0403 0.0000 0.0Bluegill 0.0000 0.0000 0.0000 0.4837 0.0338 0.0718 0.0000 0.0000 0.0000 0.2882 0.2Grubby 0.0383 0.1502 0.4765 0.2462 0.0554 0.0346 0.0000 0.0000 0.0000 0.0000 0.0Windowpane 0.0383 0.0000 0.2028 0.1884 0.0000 0.0000 0.0000 0.0393 0.3917 0.0000 0.0Oyster Toadfish 0.0000 0.0000 0.0000 0.0000 0.0554 0.1713 0.0834 0.0786 0.0805 0.0858 0.1Threespine Stickleback 0.0000 0.3966 0.2473 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Mummichog 0.0000 0.0000 0.0395 0.2946 0.0000 0.0684 0.0374 0.0588 0.0000 0.0000 0.0Striped Searobin 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.2357 0.0000 0.0445 0.0Smallmouth Flounder 0.2300 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Largemouth Bass 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.3448 0.0Northern Pipefish 0.0383 0.0000 0.0763 0.0457 0.0372 0.0000 0.0000 0.0393 0.0000 0.0000 0.0American Eel 0.0383 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0393 0.0386 0.0000 0.1Summer Flounder 0.0000 0.0690 0.0000 0.0000 0.0000 0.0692 0.0000 0.0000 0.0000 0.0758 0.0Rainbow Smelt 0.1839 0.0406 0.0369 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Hogchoker 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0998 0.0000 0.1174 0.0413 0.0Butterfish 0.0383 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.1230 0.0000 0.0000 0.0Golden Shiner 0.0000 0.0000 0.0000 0.2235 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0American Shad 0.0000 0.0406 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.1Gizzard Shad 0.0625 0.0406 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0345 0.0Black Crappie 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.1034 0.0Black Sea Bass 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Striped Killifish 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0390 0.0000 0.0Little Skate 0.0625 0.0000 0.0000 0.0457 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Scup 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0786 0.0000 0.0000 0.0Yellow Perch 0.0000 0.0000 0.0000 0.0593 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Atlantic Cod 0.0000 0.0000 0.0000 0.0000 0.0554 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Crevalle Jack 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Lookdown 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Blueback Herring 0.0000 0.0000 0.0000 0.0457 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Common Carp 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0413 0.0Lumpfish 0.0000 0.0413 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Pumpkinseed 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0413 0.0Conger Eel 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Striped Bass 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0Fourspot Flounder 0.0000 0.0000 0.0000 0.0000 0.0000 0.0373 0.0000 0.0000 0.0000 0.0000 0.0
42

Table 4. Total estimated monthly catch for numerically dominant finfish and 'all others' partitioned by low and

 high-pressure wash systems, Manchester Street Station, January - December 2005.

Atlantic Menhaden Atlantic Silverside Winter Flounder Atlantic Herring

Low High Percent Low High Percent Low High Percent Low High Percent 

Pressure Pressure Low Pressure Pressure Low Pressure Pressure Low Pressure Pressure Low

Jan 10,772 26,128 29.2% 1,749 19 98.9% 492 2,797 15.0% 21 0 100.0%

Feb 981 5,052 16.3% 1,727 2,408 41.8% 958 1,580 37.7% 0 0

Mar 0 0 28 7 80.0% 7,583 10,911 41.0% 0 0

Apr 0 0 0 0 754 133 85.0% 0 0

May 0 0 0 0 126 350 26.5% 0 0

Jun 0 0 0 0 65 37 63.7% 28,908 13,580 68.0%

Jul 8 0 100.0% 0 0 1,018 93 91.6% 115,363 13,025 89.9%

Aug 22,086 20,903 51.4% 7 40 14.9% 2,426 14 99.4% 7 6 53.8%

Sep 148 320 31.6% 13 7 65.0% 160 153 51.1% 0 0

Oct 64,105 40,801 61.1% 8 0 100.0% 98 18 84.5% 0 0

Nov 1,593 1,290 55.3% 5 10 33.3% 15 36 29.4% 0 0

Dec 0 0 87 28 75.7% 79 27 74.5% 0 0

Total 99693 94494 51.3% 3624 2519 59.0% 13774 16149 46.0% 144299 26611 84.4%

Cunner Tautog White Perch Silver Hake

Low High Percent Low High Percent Low High Percent Low High Percent 

Pressure Pressure Low Pressure Pressure Low Pressure Pressure Low Pressure Pressure Low

Jan 7 13 35.0% 14 6 70.0% 0 6 0.0% 101 50 66.9%

Feb 7 0 100.0% 21 26 44.7% 34 0 100.0% 540 782 40.8%

Mar 0 7 0.0% 43 6 87.8% 426 148 74.2% 34 14 70.8%

Apr 31 0 100.0% 26 0 100.0% 0 0 0 0

May 37 76 32.7% 12 26 31.6% 0 0 0 0

Jun 86 0 100.0% 13 12 52.0% 0 0 0 0

Jul 12 0 100.0% 8 0 100.0% 0 0 0 0

Aug 527 37 93.4% 67 20 77.0% 0 0 0 0

Sep 175 7 96.2% 156 13 92.3% 7 0 100.0% 0 0

Oct 148 0 100.0% 191 0 100.0% 0 0 0 0

Nov 66 0 100.0% 63 8 88.7% 0 0 0 0

Dec 19 7 73.1% 64 7 90.1% 13 0 100.0% 6 7 46.2%

Total 1115 147 88.4% 678 124 84.5% 480 154 75.7% 681 853 44.4%

Atlantic Tomcod All Others

Low High Percent Low High Percent 

Pressure Pressure Low Pressure Pressure Low

Jan 101 51 66.4% 75 74 50.3%

Feb 35 0 100.0% 96 20 82.8%

Mar 71 34 67.6% 142 40 78.0%

Apr 137 0 100.0% 235 38 86.1%

May 9 76 10.6% 24 35 40.7%

Jun 6 8 42.9% 42 193 17.9%

Jul 0 47 0.0% 20 17 54.1%

Aug 540 0 100.0% 130 16 89.0%

Sep 20 0 100.0% 94 64 59.5%

Oct 0 0 152 60 71.7%

Nov 19 0 100.0% 176 89 66.4%

Dec 133 0 100.0% 574 65 89.8%

Total 1071 216 83.2% 1760 711 71.2%
Table 5. Estimated numbers of fish impinged on the Manchester Street Station revolving screens January-December by species, 1975-2005 (1980 excluded).

Species 1975 1976 1977 1978 1979 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1 1995 2 

African pompano 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

 Alectis ciliarisAlewife 1,459 518 1,484 491 518 335 817 770 213 1,640 3,498 636 1,113 226 659 197 6 0 150 26  Alosa pseudoharengusAmerican eel 119 168 238 245 707 1,106 718 647 209 187 106 330 103 124 62 324 34 51 24 391  Anguilla rostrataAmerican shad 0 0 0 0 0 0 208 56 0 14 0 0 0 0 0 0 0 0 0 0 

 Alosa sapidissimaAtlantic cod 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Gadus morhuaAtlantic herring 28 28 21 121 0 19 0 46 84 16,515 11 1,948 104 830 288 452 187007 1 Clupea harengusAtlantic mackerel 0 0 0 19 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 0 

 Scomber scombrusAtlantic menhaden 50,630 12,734 24,619 18,876 494 1,285 54 2,147 827 18,831 29,440 1,510 2,344 9,974 2,976 38,836 159,328 247 25 138 7 Brevoortia tyrannusAtlantic moonfish 0 0 0 0 0 0 0 0 0 216 0 0 0 0 0 0 0 0 0 44 

 Selene setapinnisAtlantic silverside 1,305 1,106 21,129 1,854 1,212 12,196 24,583 9,687 97 4,677 4,471 11,273 24,824 14,873 12,365 3,089 3,215 804 1,071 1,528 3 Menidia menidiaAtlantic tomcod 0 14 0 244 247 297 2,359 255 1,367 2,197 329 307 158 36 281 0 15 39 742 348  Microgadus tomcodBanded killifish 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

Fundulus diaphanusBay anchovy 0 98 658 0 308 461 159 585 60 59 0 0 95 1,385 161 350 96 0 0 563  Anchoa mitchilliBlack crappie 0 0 0 0 0 0 0 0 0 0 0 0 54 113 0 0 0 0 0 13 

 Pomoxis nigromaculatusBlack sea bass 0 0 21 0 19 0 0 0 0 0 0 0 0 0 0 0 0 0 0 33  Centropristis striataBlack spotted stickleback 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Gasterosteus wheatlandiBlueback herring 168 70 273 791 492 1,089 7,799 500 301 502 164 233 1,012 164 247 164 0 0 6 110  Alosa aestivalisBluefish 0 0 42 17 73 157 869 810 40 265 30 75 0 128 48 0 0 0 0 7 

 Pomatomus saltatrixBluegill 84 154 287 338 967 492 1,100 224 744 58 89 803 49 254 50 0 69 0 29 70  Lepomis macrochirusBlue runner 0 24 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 50 

 Caranx chrysosBrown bullhead 0 0 0 0 33 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7  Ameiurus nebulosus
Table 5. (continued).

Species 1975 1976 1977 1978 1979 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1 1995 2 

Brown Trout 00000000000000000000

 Salmo truttaButterfish 0 112 112 37 114 90 0 0 52 283 367 0 95 386 48 40 0 0 0 18  Peprilus triacanthusChain pickerel 0 0 0 19 0 0 56 0 0 140000000000

 Esox nigerCommon carp 0 0 0 0 50 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Cyprinus carpioConger eel 0 0 0 0 0 0 0 14 0 0 0 0 0 0 0 0 0 0 0 0  Conger oceanicusCrevalle jack 0 0 21 0 0 112 252 94 0 0 0 0 0 68 0 0 0 0 0 0  Caranx hipposCunner 28 14 168 124 34 51 380 0 0 0 0 0 0 0 51 246 19 0 128 529 

 Tautogolabrus adspersusFourspine stickleback 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 12 0  Apeltes quadracusFourspot flounder 0 14 0 0 0 22 0 48 0 0 0 0 0 42 0 0 19 0 0 0  Paralichthys oblongusGizzard shad 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Dorosoma cepedianumGolden shiner 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Notemigonus crysoleucasGrubby 0 0 0 0 0 0 0 0 0 73 0 88 0 0 0 0 0 12 10 34  Myoxocephalus aenaeusHogchoker 0 0 0 0 17 21 0 0 61 22 1,367 365 577 0 192 388 8 12 0 57  Trinectes maculatusInland silverside 00000000000000000050

 Menidia beryllinaKillifish 14 - - - - - - - - - - - - - - - - - - - -  Fundulus spp.Largemouth bass 0 0 21 19 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

 Micropterus salmoidesLittle skate 14 0 0 17 179 150 124 0 63 795 401 550 394 168 62 0 39 13 3 40  Raja erinaceaLonghorn sculpin 00000000000000000070 Myoxocephalus octodecemspinosusLookdown 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Selene vomerLumpfish 0 0 19 19 17 0 0 0 0 14 0 0 61 0 0 0 0 0 0 0 

 Cyclopterus lumpusMullet 0 0 0 19 0 0 60 0 14000000000000

 Mugil spp.
Table 5. (continued).

Species 1975 1976 1977 1978 1979 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1 1995 2 

Mummichog 1,057 1,160 6,433 4,355 8,479 6,198 60,974 115 0 750 165 683 42 331 482 0 165 326 200 139  Fundulus heteroclitusNorthern kingfish 0 0 0 0 17 0 0 0 0 0 0 0 0 0 48 0 0 0 0 0 

 Menticirrhus saxatilisNorthern pipefish 48 56 56 0 17 41 114 0 48 84 47 73 0 120 234 101 7 110 539 529  Syngnathus fuscusNorthern puffer 00000000000000000000 Sphoeroides maculatusNorthern searobin 0 14 0 0 0 0 0 0 0 0 0 0 0 0 208 0 0 0 0 41 

 Prionotus carolinusOyster toadfish 0 0 0 0 0 0 0 0 0 0 0 0 0 54 0 0 0 0 0 0  Opsanus tauPollock 0 0 0 0 0 49 277 0 0 0 0 0 0 0 0 0 0 0 0 0  Pollachius virensPumpkinseed 0 0 0 0 0 0 140 0 0 0 0 0 0 0 0 0 0 0 21 0  Lepomis gibbosusRainbow smelt 0 28 35 34 644 150 31 0 0 0 0 0 53 78 0 0 0 0 0 11  Osmerus mordaxRed hake 0 294 413 78 1,387 96 620 0 0 87 15 0 51 175 0 0 0 20 0 6 

 Urophycis chussRock gunnel 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

 Pholis gunnellusRound herring 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Etremeus teresSand lance 0 0 0 0 16 17 0 0 0 0 0 0 63 0 0 0 0 0 0 0  Ammodytes sp.Scup 0 0 0 0 0 0 0 0 0 0 0 0 0 0 51 92 672 0 0 7 

 Stenotomus chrysopsSeaboard goby 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

 Gobiosoma ginsburgiSea lamprey 00000000000000000000 Petromyzon morinusSheepshead minnow 00000000000000000000 Cyprinodon variegatusSilver hake 992 3,080 6,272 2,370 11,987 424 2,810 2,263 156 2,900 1,723 508 1,174 1,300 1,522 0 626 212 23 47  Merluccius bilinearisSmallmouth flounder 14 0 0 0 0 0 0 0 0 0 0 68 0 32 0 0 0 21 0 0 

 Etropus microstomusSmooth dogfish 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 6 

 Mustelus canisSpot 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 

 Leiostomus xanthurus
Table 5. (continued).

Species 1975 1976 1977 1978 1979 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1 1995 2 

Spotted hake 28 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Urophycis regiaStriped anchovy 00000000000000000000

 Anchoa hepsetusStriped bass 0 0 0 0 17 0 0 0 0 0 0 0 0 0 0 0 0 0 0 13 

 Morone saxatilisStriped cusk-eel 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 7 0 

 Ophidion marginatumStriped killifish 0 196 762 877 826 1,703 2,589 99 0 89 23 0 369 442 463 0 25 37 25 14  Fundulus majalisStriped searobin 290 14 21 33 36 0 0 0 0 0 150 0 0 0 0 471 718 43 0 0 

 Prionotus evolansSummer flounder 0 0 0 0 0 0 0 0 361 245 0 0 0 0 0 0 0 0 0 0  Paralichthys dentatusTautog 34 56 56 145 6,394 720 1,895 56 95 84 0 316 1,343 495 152 214 20 92 258 445  Tautoga onitisThreespine stickleback 28 98 56 52 3,004 240 51 56 0 716 141 520 2,661 187 75 0 110 136 59 0  Gasterosteus aculeatusWeakfish 1,543 28 1,253 751 42 624 2,470 48 0 49 16 60 0 0 52 464 82 0 0 6 

 Cynoscion regalisWhite crappie 00000000000000000000

 Pomoxis anularisWhite hake 14 28 217 23 417 0 0 0 0 75 0 0 0 0 0 0 0 0 0 0 

 Urophycis tenuisWhite perch 14 0 217 0 130 178 40 312 240 163 11 56 53 137 41 160 392 2,896 232 19  Morone americanaWhite sucker 0 0 0 0 84 44 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Catostomus commersoniWindowpane 129 196 259 208 1,388 817 89 93 81 1,967 673 798 523 1,148 78 163 123 38 65 70  Scophthalmus aquosusWinter flounder 2,381 1,148 1,503 3,017 15,101 3,273 11,207 4,212 1,572 25,340 748 7,106 5,516 2,365 10,823 2,422 1,660 1,935 912 4,295 1 Pleuronectes americanusYellow perch 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0  Perca flavesensTotal 60,421 21,748 66,647 35,193 55,467 32,467 122,845 23,137 6,811 78,911 43,985 28,306 42,768 35,468 32,139 47,610 167,635 7,151 4,566 9,741 13Number of species 22 27 28 29 35 31 29 23 21 31 23 22 24 28 28 17 24 19 26 36 1Due to repowering upgrades sampling in 1994 was only possible through September.2Sampling in 1995 began in mid-July once new equipment became functional.
 Normandeau Associates, Inc. 

Table 6. Correlation coefficients between numbers of fish (all species) impinged at Manchester Street Station in 

24-hour periods, water temperature and intake flow, 1992-2005. For 1999-2005, coefficients were also 

calculated after removing menhaden from the counts. 

 All Species Without Menhaden

 Water Intake Water Intake 

 Temperature Flow Temperature Flow 

1992 Number of fish rs -0.7103 0.2971 Boxed cells indicate statistically 

Log number of fish r -0.6953 0.3041 significant values.

n = 47 

1993 Number of fish rs -0.4613 -0.210 

Log number of fish r -0.4713 -0.187

n = 51 

1994 Number of fish rs -0.185 0.5413

Log number of fish r -0.167 0.5833 

n = 38 

1995 Number of fish rs -0.185 0.5413

Log number of fish r -0.167 0.5833 

n = 24 

1996 Number of fish rs 0.069 0.3341

Log number of fish r 0.085 0.2811 

n = 52 

1997 Number of fish rs -0.4782

 0.5223 

Log number of fish r -0.3862 0.4603 

n = 52 

1998 Number of fish rs 0.161 0.2931 

Log number of fish r 0.2721 0.2961 

n = 53 

1999 Number of fish rs 0.3041

 0.3762 -0.243 0.382

Log number of fish r 0.4152 0.2991 -0.160 0.273 

n = 52 

2000 Number of fish rs 0.009 -0.087 0.167 -0.041

Log number of fish r 0.032 0.139 0.249 -0.137 

n = 48 

2001 Number of fish rs 0.3121

 0.121 -0.071 0.025

Log number of fish r 0.4262 0.250 -0.016 0.061 

n = 52 
 Normandeau Associates, Inc. 

Table 6. (continued). 

 All Species Without Menhaden

 Water Intake Water Intake 

 Temperature Flow Temperature Flow

2002 Number of fish rs 0.084 -0.105 -0.109 -0.040

Log number of fish r 0.240 -0.096 -0.004 0.023 

n = 52 

2003 Number of fish rs 0.146 0.102 -0.109 -0.040

Log number of fish r 0.144 0.2921 -0.004 0.023 

n = 53 

2004 Number of fish rs -0.032 -0.057 -0.209 -0.001

Log number of fish r -0.002 -0.048 -0.004 0.023 

n = 52 

2005 Number of fish rs -0.132 0.228 -0.100 0.143

Log number of fish r -0.082 0.152 0.004 -0.266 

n = 52 

Pooled Number of fish rs 0.039 -0.010 

Log number of fish r 0.1102 0.077 

 n = 490 

1

Significant p < 0.05 ; 2Significant p < 0.01 ; 3Significant p < 0.001 

rs = Spearman rank ; r = Pearson correlation coefficient 
Table 7. Estimated numbers of invertebrates impinged on the Manchester Street intake screens by species and month, 1992-2003. New screen and wash system installed Octob

 No data available for that period.  Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

1992

Blue crab 0 0 0 0 0 6 10 0 0 0 21 

Callinectes sapidus

Lady crab 0 0 0 0 32 70 0 0 19 891 2939  Ovalipes ocellatusMud crab 0 0 0 7 0 0 15 0 0 0 0 

Neopanopeus sayi

Rock crab 0 0 0 7 6 0 0 0 0 0 0 

Cancer irroratus

Marsh grass shrimp 0 0 0 0 0 0 0 0 0 64 0 

Paleomonetes vulgaris

7-spine bay shrimp 0 0 0 7 0 6 14 0 63 0 0 

Crangon septemspinosa

Starfish 0 0 0 0 0 0 0 0 0 0 0 

Asterias forbesi

1993

Blue crab 0 0 0 0 5 14 56 125 98 0 0 

Callinectes sapidus

Horseshoe crab 0 0 0 0 5 5 0 0 0 0 27 

Limulus polyphemus

Lady crab 0 0 0 0 12 7 0 0 0 0 18 

Ovalipes ocellatus

Rock crab 0 0 0 0 0 0 0 0 0 0 0 

Cancer irroratus

Mantis shrimp 0 0 0 0 7 0 0 0 0 0 6  Squilla empusa7-spine bay shrimp 0 0 0 0 5 0 0 0 0 0 0 

Crangon septemspinosa

Starfish 0 0 0 0 0 0 0 0 0 0 0 

Asterias forbesi
Table 7 (continued). 

 Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

1994

Blue crab 5 0 0 0 0 17 13 35 0 

Callinectes sapidus

Green crab 0 0 0 0 5 0 0 0 0 

Carcinus maenas

Lady crab 0 7 0 35 0 0 0 0 0 

Ovalipes ocellatus

Marsh grass shrimp 744 0 0 0 46 0 0 0 172 

Paleomonetes vulgaris

7-spine bay shrimp 0 183 0 0 0 0 0 0 0  Crangon septemspinosaStarfish 34 12 174 0 0 0 0 0 0 

Asterias forbesi

1995

Blue crab 0 0 0 630 0 

Callinectes sapidus

Green crab 609 375 0 40 1898 

Carcinus maenas

Horseshoe crab 0 0 0 0 6 

Limulus polyphemus

Lady crab 7 0 0 261 23428 

Ovalipes ocellatus

Rock crab 0 0 0 7 0 

Cancer irroratus

Spider crab 0 0 0 0 45 

Libinia emerginata

Mantis shrimp 0 0 0 0 8660 

Squilla empusa

7-spine bay shrimp 70 0 0 0 0 

Crangon septemspinosa
Table 7 (continued). 

 Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

1996

Blue crab 0 0 0 0 977 456 1452 1905 1414 2723 171 

Callinectes sapidus

Green crab 0 0 21 86 135 704 591 64 62 35 52 

Carcinus maenas

Horseshoe crab 0 0 0 0 20 5 46 0 0 0 0  Limulus polyphemusLady crab 0 0 0 0 59 35 0 30 4024 31042 25908  Ovalipes ocellatusRock crab 0 0 0 7 0 7 0 0 0 0 0  Cancer irroratus Spider crab 0 0 0 0 0 0 14 0 0 0 6 

Libinia emerginata

Mantis shrimp 0 0 0 0 0 0 0 0 0 103 641 

Squilla empusa

7-spine bay shrimp 15603 9488 6121 8909 2064 247 28 0 0 0 0 

Crangon septemspinosa

1997 

Blue crab 0 0 0 0 39 545 215 353 69 40 0 

Callinectes sapidus

Green crab 40 0 0 0 0 0 0 0 2853 778 1464 

Carcinus maenas

Horseshoe crab 0 0 0 0 0 0 0 0 0 0 6  Limulus polyphemusLady crab 223 12 0 87 169 244 17 42 130 264 476  Ovalipes ocellatusRock crab 0 0 0 0 0 0 17 0 0 0 0 

 Cancer irroratus 

Spider crab 0 0 0 0 0 0 0 0 0 0 6 

Libinia emerginata

Mantis shrimp 0 0 0 0 0 0 0 0 0 0 130 

Squilla empusa

7-spine bay shrimp 3395 318 6332 3060 2059 1298 330 0 334 0 0 

Crangon septemspinosa

Squid 0 0 0 0 0 0 0 7 0 0 0 

Loligo pealii
Table 7 (continued). 

 Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

1998

Blue crab 0 0 0 6 255 0 414 1282 1125 4654 340 

Callinectes sapidus

Green crab 566 115 2179 308 200 12 355 108 195 252 656 

Carcinus maenas

Horseshoe crab 0 0 0 0 0 0 0 0 0 0 0  Limulus polyphemusLady crab 0 0 0 0 80 0 0 0 9 257 35  Ovalipes ocellatusMud crab 0 0 0 0 0 0 0 0 0 0 254 

Neopanopeus sayi

Rock crab 0 14 0 0 0 0 0 7 96 0 0 

 Cancer irroratus 

Spider crab 0 0 0 0 0 0 21 0 0 7 0 

Libinia emerginata

Mantis shrimp 0 0 0 0 0 0 0 0 5 6 67 

Squilla empusa

7-spine bay shrimp 1406 4039 1226 845 140 35 0 0 0 0 0 

Crangon septemspinosa

1999

Blue crab 0 5 0 21 898 941 3914 1053 5574 2119 818 

Callinectes sapidus

Green crab 120 64 74 118 51 65 102 34 0 0 0 

Carcinus maenas

Horseshoe crab 0 0 0 0 0 7 0 0 0 0 7  Limulus polyphemusLady crab 0 0 0 0 0 0 0 0 0 0 345  Ovalipes ocellatusMud crab 0 0 0 46 0 0 0 343 0 0 0 

Neopanopeus sayi
Table 7 (continued). 

 Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

1999 (continued) 

Rock crab 0 0 0 0 11 0 0 0 0 0 0 

 Cancer irroratus 

Spider crab 0 0 0 0 7 0 7 0 0 0 0 

Libinia emerginata

Mantis shrimp 0 0 0 0 0 0 0 0 0 24 117 

Squilla empusa

7-spine bay shrimp 618 16594 1059 239 0 0 163 0 0 0 0 

Crangon septemspinosa

Squid 0 0 0 8 0 0 0 0 0 0 0 

Loligo pealii 

2000

Blue crab 0 0 0 0 12 1408 6306 2766 4254 2852 220 

Callinectes sapidus

Green crab 0 0 0 53 0 0 0 0 0 0 0 

Carcinus maenas

Japanese shore crab 0 0 0 7 0 0 0 0 0 0 0 

Hemigrapsus sanguineus

Horseshoe crab 0 0 7 0 0 0 0 0 0 0 0  Limulus polyphemusLady crab 0 0 0 14 0 0 0 0 0 0 0  Ovalipes ocellatus Mud crab 0 0 0 21 0 0 0 0 0 0 0 

Neopanopeus sayi

Spider crab 0 0 0 0 0 0 7 0 0 0 0 

Libinia emerginata

Mantis shrimp 0 0 0 7 0 0 0 0 0 0 52 

Squilla empusa

7-spine bay shrimp 96950 569295 3487 1580 665 0 0 0 0 0 0 

Crangon septemspinosa

Starfish 0 0 0 14 0 0 0 0 0 0 0 

Asterias forbesi
Table 7 (continued). 

 Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

2001

Blue crab 0 0 0 0 677 1072 6443 6805 0 37 41 

Callinectes sapidus

Green crab 0 0 0 7 0 0 15 0 0 0 35 

Carcinus maenas

Japanese shore crab 0 0 0 53 0 0 15 0 0 0 0 

Hemigrapsus sanguineus

Lady crab 0 0 0 0 0 0 8 0 0 48 198  Ovalipes ocellatus Spider crab 0 0 0 0 0 7 0 0 0 0 0 

Libinia emerginata

Cancer crab 0 14 0 0 0 0 53 0 0 0 0 

Cancer spp. 

Mantis shrimp 0 0 0 0 8 0 0 0 0 0 34 

Squilla empusa

7-spine bay shrimp 20269 689 1783 395 0 260 0 0 0 0 0 

Crangon septemspinosa

2002

Blue crab 0 0 0 0 49 82 388 491 155 168 0 

Callinectes sapidus

Green crab 6 0 0 0 0 15 0 0 0 0 0 

Carcinus maenas

Lady crab 13 0 0 0 0 0 0 0 0 0 0  Ovalipes ocellatus Mantis shrimp 0 0 0 0 0 0 0 0 0 0 1831 

Squilla empusa
Table 7 (continued). 

 Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

2003

Blue crab 0 0 0 0 0 14 0 156 25 102 0 

Callinectes sapidus

Horseshoe crab 0 0 0 0 0 7 0 0 0 0 0  Limulus polyphemusLady crab 0 0 0 0 0 0 0 0 0 28 8  Ovalipes ocellatus Spider crab 0 0 0 0 0 0 0 0 0 7 0 

Libinia emerginata

Cancer crab 0 0 0 0 0 0 0 0 14 15 

Cancer spp. 

Mantis shrimp 0 0 0 0 0 0 0 0 0 7 38 

Squilla empusa

2004

Blue crab 0 0 0 0 0 7 7 0 28 7 34 

Callinectes sapidus

7-spine bay shrimp 0 42,000 0 0 35 0 0 0 0 0 43 

Crangon septemspinosa

Lady crab 0 0 0 0 0 0 0 0 47 772 265  Ovalipes ocellatus Spider crab 0 0 0 0 0 7 0 0 0 0 0 

Libinia emerginata 

Japanese shore crab 0 0 0 0 21 0 0 0 0 0 63 

Hemigrapsus sanguineus

Green crab 0 0 0 0 0 0 0 0 12 0 0 

Carcinus maenas

Cancer crab 0 0 0 14 84 0 0 0 56 0 0 

Cancer spp. 

Mantis shrimp 0 0 0 0 0 0 0 0 52 14 2,813 

Squilla empusa
Table 7 (continued). 

 Species Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov 

2005

Blue crab 0 0 0 0 0 0 0 56 245 109 356 

Callinectes sapidus

Cancer crab 0 0 0 0 0 8 0 0 0 0 5 

Cancer spp. 

Green crab 0 0 14 0 17 0 0 40 80 31 61 

Carcinus maenas

Japanese shore crab 0 0 0 0 0 25 0 0 0 0 0 

Hemigrapsus sanguineus

Lady crab 0 0 0 0 0 0 0 0 0 42 254  Ovalipes ocellatus Mantis shrimp 0 0 0 0 0 0 0 0 0 0 

Squilla empusa

7-spine bay shrimp 0 0 5,695 0 0 0 0 0 0 0 0 

Crangon septemspinosa