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Post-Impingement Fish Survival 

at Huntley Steam Station 

Winter and Fall 

1999 

FINAL REPORT 

Preparedfor: .. 

Niagura Mohawk Power Corporution 

300 Erie Boulevard West 

Syracuse, NY 13202 

Prepared by: 

Beak ConsultantsIncorporated 

I40Rotech Drive 

Laneaster, NY 14086 

April 10, 2000 
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1.0 INTRODUCTION 

1.1 Background 

Beak Consaltants Incorporated (Beak) was retained by Niagara Mohawk Power Corporation 

(NMPC) to -evaluate -._ the swival of fish impinged on newly installed through-flow Ristroph-type

traveling screens-at its Huntley Steam Station. These screens were engineered by NMPC and 

manufactured by Brackett Green Incorporated. The screening system was designed to maximize 

the survival of impinged fish for their return to the Niagara River, in accordance with Clean 

Water Act Section 316(b) requirements that the intake structure reflect the best technology 

available (BTA) for minimizing adverse environmental impact. This report presents methods 

and results for impingement survival testing conducted in January 1999 for NMPC and in 

October 1999 for NRG Huntley Power, LLC, who assumed ownership of the station in June 

1999. 

The study objectives were to: 1) evaluate the effectiveness of a low-pressure spray wash system 

for the removal of fish from the screens; 2) investigate the influence of sample collection and 

handling on the survival of impinged fish; 3) estimate the post-impingement survival of 

commonly impinged species; and 4) determine ways to optimize post-impingement survival. 

1.2 Huntley Station Description 

The Huntley Steam Station (Huntley) is located on the Niagara River in the Town of Tonawanda, 

New York. Huntley is coal-fired and has four units rated for a total of 760 megawatts (Mw). 

Five new “Ristroph-type” through-flow traveling screens were installed in the screenhouse that 

services Units 67 and 68. The new screens replaced four older, conventional traveling screens. 

Physical characteristics of the new screening system are described in Table 1. 

NRG Huntley L.L.C. 1 Beak Consultants hcorporated 

April 10,2000 File: Huntley-report-final.doc 
Circulating system water enters the plant perpendicular to the Niagara River through an intake 

structure located along a bulkheaded shoreline. Water travels under a skimmer wall and enters a 

common forebay before passing through five sets of bar racks. There is one traveling screen 

located 12 A behind each set of bar racks. The traveling screens fit into slots approximately 11 ft 

wide and 20 ft deep. Each screen is made of rectangular frames (basket sections) connected to 

form an endl&s belt. Each basket section is covered with 118-inch by %-inch “smooth tex” 

woven stainless steel cloth and has an attached hydraulically-designed fish bucket at the bottom 

to collect fish as the buckets ascend. As the screen buckets overturn at the top of the traveling 

screen, their contents are washed into a fish return trough by two inside and two outside lowpressure’spray wash headers. The screen is then subjected to a high-pressure spray wash, which 

forces remaining debris into a debris trough. The fish and debris troughs run parallel to all five 

screens troughs (fish trough above the debris trough) before combining into a single 18-inch 

diameter pipe, which discharges into the Niagara River approximately 350 �tdownstream of the 

intake. 

NRG Huntley L.L.C. 2 Beak Consultants Incorporated 

April 10,2000 File: Huntley-report-finaLdoc 
3.0 RESULTS AND DISCUSSION 

3.1 Low-Pressure Spray System Efficiency Testing 

Recovery rates for marked centrarchids ranged from 88% to 100% (Table 2). Based on testing at 

Screen #5, the best results (100% recovery) came with spray pressures of 1.5 and 5 psi. Testing 

at Screen #5 also showed that nearly all fish missed by the fish return trough were collected in 

the debris trough. For Screens #6 through #9, recovery rates from the fish return trough 

approached loo%, with the exception of Screen #7 (88%). 

At Huntley, the lower inside and outside spray nozzles of most screens are directly opposed. The 

lower inside spray wash on Screen #7 was aimed slightly above the lower outside spray and 

appeared to have weaker pressure. The pressure differential andor orientation of the lower 

outside spray may explain the lower collection efficiency at Screen #7, if they are forcing fish 

between the flap seal and the descending screen. 

For the test conducted on Screen #6 using dead emerald shiners, only 37% of the fish released 

were recovered in the fish return trough (Table 3). The remainder of the fish were collected in 

the debris trough for a combined efficiency of 100%. 

Using dead rainbow smelt, the recovery rates for juveniles (75-95 mm) from Screens #5, #6, and 

#9 were 63, 42 and 52%, respectively (Table 3). The recovery rates for adults (130-140 m) 

from Screens #5, #6, and #9 were 98, 86 and 88%, respectively. The combined collection 

efficiency for the fish and debris troughs at Screens #5 and #6 were 89 to LOO. 

Simultaneous collections of live, “naturally impinged fish” fiom the fish return and debris 

troughs downstream of Screens #5 and #6 showed that 83% of the emerald shiners and 91% of 

the juvenile and adult rainbow smelt were collected from the fish return trough (Table 4). These 

NRG Huntley L.L.C. 9 Beak ConsultantsIncorporated 

April 10,2000 File: fIuntleyreport-&aI.doc 
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high recovery rates in the fish return trough were in contrast to the 37% recovery of emerald 

shiners and 42 to 63% recovery of juvenile rainbow smelt during tests using marked dead fish 

releases (Table 3). Therefore, better collection efficiency may be expected for live fish than for 

dead fish. 

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I Detailed t6st results are presented in Appendix Tables A-2 through A-4. 

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3.2 Collection and Handling Mortality Testing 

I During testing on January 20, 1999, none of the 49 golden shiners (handling controls) or 36 

golden shiners (holding controls) held for 24 hr died (Table 6). Therefore, no.__adjustments to 

impingement mortality estimates would be necessary to account for the effects of handling or I ..-_-_ 

holding. 

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1 3.3 Post Impingement Survivai 

I January Survival 

During January testing, a total of 6,120 fish and 14 species were collected for survival evaluation 

during five nights of sampling (Table 6). Targeted species included 3,418 rainbow smelt, 2,201 

emerald shiners, 315 juvenile gizzard, 30 'alewife and three adult gizzard shad. An additional 

6,364 fish were collected but not evaluated �or extended survival. 

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I Rainbow smelt was the most abundant species collected. Fish tested ranged in length ftom 56 to 

140 rnm (Appendix Table �3-1). There was a bimodal length frequency distribution, separating 

smelt into two size groups (approximating juveniles and adults) at about 100 inm. Overall, 

impingement survival for rainbow smelt was 84.2% (Table 7). The ratio of juveniles (<lo0 mm) 

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to adults (>lo0 mm) occurring within the measured fish classified as initially dead or stressed, 

dead or stressed at 24 hr, and alive at 24 hr was applied to the total number of fish (measured and 

Nl2G Huntley L.L.C. 10 Beak Consultants Incorporated 

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unmeasured) in each of these three categories to estimate initial and extended survival of juvenile 

and adult rainbow smelt. By this method, the extended survival for juvenile and adult rainbow 

smelt was estimated to be 74.4% and 94.3%, respectively (Table 7). 

Emerald shiner was the second most abundant species collected. Fish tested ranged in length 

from 48 to -105m in a relatively uniform size distribution (Appendix Table B-2). Impingement 

survival for emerald shiners was 97.5% (Table 6). 

Juvenile gizzard shad was the third most abundant species collected. Fish tested ranged in length 

fiom 86 to 193 rnm (Appendix Table B-3). Overall, impingement survival for juvenile gizzard 

shad was 5.1% and initial survival was 14.9% (Table 6). Only three adult gizzard shad were 

collected, ranging in length f7om 262 to 289 m. All three were severely stressed at the time of 

collection, and their survival was considered to be zero. The low survival for gizzard shad could 

be a result of cold water temperature, which at the time of the study was near O°C. Gizzard shad 

in the Niagara River are at the northern limits of their geographic range (Smith 1985) and may 

have been thermally stressed prior to impingement. 

Alewife were not abundant, and only 30 specimens were collected, ranging in length from 89 to 

204 mm (Appendix Table B-4). Of these 30 fish, four were dead and 26 were stressed at the time 

of collection (Table 6). Since initially stressed fish were treated as being dead for this testing, 

the initial and overall mortality was considered to be 100% for alewife. As with the gizzard 

shad, the low survival could be related to water temperature. Alewife are at the northern limit of 

their range in the Niagara River and Lake Erie, and typically move to deep water to avoid cold 

winter temperatures (Smith 1985). In laboratory experiments, adult alewife fiom Lake Michigan 

lost orientation and ceased feeding and schooling at temperatures between 2.0 and 2.8 "C (35.5­

37'F) (Colby 2971). Water temperatures during testing were near 0"C (Appendix C). 

Ten non-target species were collected, including trout-perch, yellow perch, rock bass, spottail 

shiner, white sucker, white perch, smallmouth bass, bluntnose minnow, darters and redhorse 

sucker. No species were abundant, except for trout-perch. kw $& s ~ I ~(g --~ - -j 

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NRG Huntley L.L.C. 11 

April 10,2000 File: Huntley-report-fmddoc 

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1 October Survival 

During October testing, a total of 3,258 fish and 15 species were collected for survival evaluation 

I during five nights of sampling (Table 8). Sample sizes for targeted species included 1,824 

rainbow smelt, 628 emerald shiners, 183 alewife, and 65 gizzard shad. Other relatively abundant 

I species incfuded spottail shiner (231' fish), rock bass (180 fish), and white bass (127 fish). 

I The extended (24-hr) survival rate for rainbow smelt in October was estimated to be 48.0% 

(Table 8). This rate is lower than the rate (84.2%) derived fiom testing in January for juveniles

I and adults combined, and lower than the juvenile survival (74.6%) in January (Table 7). 

Rainbow smelt in October ranged in length fiom 48 mm to 135 mm (Appendix Table B-5), with 

I a mean length of approximately 65 111111,compared to a mean length of 88 mrn inJanuary. 

1 The estimated survival rate of emerald shiners (97.5%) in October was nearly identical to the rate 

(97.3%) estimated from testing in January. Emerald shiners tested ranged in length from 40 to 

1 100 mm (Appendix Table 3-6). Two other abundant species with high survival in January ,i

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continued to demonstrate high survival rates in October: spottail shiner (97.8%) and rock bass ,-­ ,-," [., $Ji"J 1 .~ (98.9%). .; ,: .: 

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II Most gizzard shad collected and tested in October were juveniles (length fkequency data provided 

in Appendix Table B-7). Their estimated 24-hr survival rate (96.9%) was much improved over 

the 5.1% survival rate recorded for juvenile gizzard shad in January. Water temperatures in the 

intake during testing ranged fiom 11.5 "C to 14 "C. These temperatures were well above the 

temperatures that could cause thermal stress for gizzard shad, thus possibly accounting for the 

higher survival than observed in January. 

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a Alewife, the species targeted for October sampling in order to increase sample sizes, experienced 

an improved 24-hr survival rate of 22.4% for a sample of 183 fish (Table 8), compared to 0% 

1 survival in January for a sample of 30 fish (Table 6). Alewife tested in October ranged in length 

from 79 to 134 mm (Appendix Table B-8) and most likely included young-of-the-year fish. 

I NRG Huntley L.L.C. 12 Beak Consultants Incorporated 

April 10,2000 File: Huntiey-report-final.doc 
Water QualiQ Monitoring and Station Operating Conditions 

Intake temperatures vaned little during each of the two study periods. Water temperatures 

ranged from 0 to 2 "Cin January (Appendix Table C-1) and 11.5 to 14 "Cin October (Appendix 

Table C-3): DO concentrations (Appendix Tables C-1 and C-3) remained at, or near, saturation. J 

All circulaling and service water pumps remained on line during the study (Appendix Tables C-1 

and C-3). Water quality in the extended survival holding tanks was generally the same as at the 

intake (Appendix Tables C-2 and C-4). 

April IO,2000 File: HUntley-report-hal.doc 
4.0 OPTIMIZATION 

The traveling screens as installed at Huntley have incorporated into their designs many fish 

mortality minimizing features, They include: 1) smooth woven wire screen; 2) “Ristr~ph”fish 

buckets wit6 a modified bucket lip to reduce turbulence in the bucket; and 3) separate fish and 

debris spray wash systems. 

Improvements to collection efficiency have the effect of improving fish survival. This assumes 

that fish not captured in either the fish or debris troughs are sent through the cooling system and 

experience mortality. The screens are designed to direct impinged fish into the fish trough in 

order to avoid exposure to the high pressure debris sprays. Collection efficiency results indicate 

few fish are missed by the screens and sent through the plant. Results show that the majority of 

fish are captured in the fish trough, and a high percentage of remaining fish are captured in the 

debris trough. 

Potential actions to improve collection efficiency for the low pressure sprays at Huntley are as 

follows. 

The gap between the flap seal and the descending screen should be minimized. We did not 

measure this gap, but the flap seal did not appear to come into close contact with the screen. 

We recommend that the flap seal be adjusted and re-tested. Since collection efficiency is 

already high, only small improvements are necessary. 

Screen # 7 should be examined more closely, particularly the flap seal. 

The lower outside spray nozzles are presently being directed towards the screen. This may 

be forcing fish into the gap between the flap seal and the screen. This row of nozzles should 

be re-directed. 

NRG Huntley L.L.C. 14 Beak Consultants hcorporated 

April 10,2000 File: Huntky_repo~-f~~l.doc 
5.0 SUMMARY 

The spray wash and collection system efficiently removes impinged fish from the traveling 

screen to the fish return trough. The survival tests conducted during this study indicate that a 

large perceniage of the impinged fish are in good condition for return to the river, as reflected by 

their conditfobn within the fish return trough. Modifications made to the traveling screens and 

spray wash system have positively affected the 24-hr, post-impingement survival rate of the fish 

impinged at Huntley. For many species, the 24-hr post impingement survival rates now 

approach or equal 100%. Survival rates also may be underestimated because stressed fish were 

considered to be dead. For these reasons, further refinements in screening system design are not 

likely to produce tangible increases in survival. 

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I NRG Huntley L.L.C. 15 Beak Consultants Incorporated

April 10,2000 File: Huntley-report-fmLdoc 

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Table I. Physical characteristics of the newly installed traveling screens 

at Huntley Steam Station. 

GeneraVSite Data Huntlev Station 

[numberof traveling screens I 1 five 

manufacturer 

operating deck level 

design high water level 

desim low water level 563.0 

fchannel base level I 1 552.9 I 

Hydraulic Data 

screen capacity 

velocity trough mesh 

head loss across mesh 

/total head loss across screen 1 I - I I 4 

lapproach velocity 1 1 <l’lsec 1 

Screen DaIta 

[effective screen width -7 I 9‘7 1/2”

Inumber of basket sections I

lmesh opening size 

mesh material 

mesh diameter 

deuth of water in fish bucket 

1width of water in fish bucket 

number of inside spray headers 

number of outside spray headers 

t 31 1 

1 

1 tW0 

two 

kmnber of spray nozzles per spray header 19/18 

inside spray pressure 5-10 psi 

outside spray pressure I total low pressure water required 

I 5-10 psi 

262-370 gprn 
Table 1. Continued. 

High Pressure Debris Spray System Data 

number of inside spray headers 

number of spray nozzles per spray header 

inside s~ravDressure 

1high Dressure water reauired 1 

Fish,Return System Data 

volume of water supplied to fish trough 

mmox. vol. of water sumlied to fish return 

!method of fish trans~ort I 

(diameterof fish return ube 1 

approximate length of fish return 

approximate velocity 

I9iio/

80 Dsi 

1 256 mm 

615 gpm 

37506 gpm 

gravity 

18” I.D. 
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Table 2. Summary of collection efficiency results using centrarchids 

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I Screen # 5’ 

I Screen # 6 

Screen # 7 

i Screen # 8 

I Screen # 9 

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at the Huntley Station, January 21,1999. 

fish return trough 

spray pressure (psi) spray pressure (psi) 

100% 100% 94% 92% 100% 100% 98% 98% 

98% 100% 

88% NA 

100% NA 

100% NA 

NA = debris trough was inaccessible 

1 HmtcolEF.xls 
Table 3. Summary of collection efficiency results using emerald shiner 

and two sizes of rainbow smelt at the Huntley Station, 

January 23 and 26,1999. 

fsh return trough I 1 fish return & debris troughs I 

rainbow smelt rainbow smelt 

63% 98% 89% 100% 

37% 42% 86% 100% 96% 96% 

52% 88Yo 
Table 4. Numbers of naturally impinged fish collected in the fish and debris 

troughs at the Huntley Station, January 2526,1999. 

number number percent of 

recovered recovered recovered fish 

from fish from debris collected in 

size(mm) trough trough fish trough 

emerald shiner 70-100 104 22 83% 

rainbow smelt 75-140 995 95 91% 

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