U.S. Department of the Interior 

U.S. Geological Survey

FISH-COMMUNITY COMPOSITION IN COWANESQUE RIVER 

UPSTREAM AND DOWNSTREAM OF THE COWANESQUE DAM, 

TIOGA COUNTY, PENNSYLVANIA, 1998

by Robin A. Brightbill and Michael D. Bilger

Open-File Report 99-208

prepared in cooperation with the

U.S. ARMY CORPS OF ENGINEERS

Lemoyne, Pennsylvania 

1999
U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

For additional information 

write to:

District Chief

U.S. Geological Survey

840 Market Street

Lemoyne, Pennsylvania 17043-1586

Copies of this report may be 

purchased from:

U.S. Geological Survey 

Branch of Information Services 

Box 25286, Federal Center 

Denver, Colorado 80225-0286
CONTENTS

Page

Abstract....................................................................................1

Introduction ................................................................................ 2

Study methods .............................................................................. 4

Fish sampling ......................................................................... 4

Habitat quantification .................................................................. 4

Data analysis.......................................................................... 4

Fish-community composition.................................................................. 6

Upstream reach ....................................................................... 8

Downstream reach ..................................................................... 8

Summary.................................................................................. 10

References cited ............................................................................ 11

Appendix.................................................................................. 13

ILLUSTRATIONS

1. Map showing site location of reaches sampled for fish communities upstream

and downstream of the Cowanesque Dam, Tioga County, Pa., 1998 ............. 3

TABLES

1. Taxa list, number of individuals, and total and average weights by species for 

fish communities upstream and downstream of Cowanesque Dam, Pa., 

1998 .................................................................... 6

2. IBI score for fish communities upstream and downstream of Cowanesque Dam,

Pa., 1998 ................................................................ 7

3. Habitat assessment upstream and downstream of Cowanesque Dam, Pa., 1998 ....... 7
CONVERSION FACTORS AND ABBREVIATIONS 

Multiply By To obtain

millimeter (mm) 

meter (m) 

kilometer (km)

square meter (m2) 

square kilometer (km2)

gram (g)

degree Fahrenheit (F)

Abbreviated water-quality units used in report:

|lS/cm, microsiemens per centimeter at 25 degrees Celsius

Length

0.03937

3.281

0.3861

Area

10.76

0.3861

Mass

0.03527

Temperature

°F=1.8°C+32

inch

foot

mile

square foot

square mile

ounce, avoirdupois

degree Celsius
Fish-Community Composition

in Cowanesque River Upstream and Downstream

of the Cowanesque Dam, Tioga County, Pennsylvania, 1998

by Robin A. Brightbill and Michael D. Bilger

ABSTRACT

The U.S. Army Corps of Engineers, Baltimore District, has been conducting biological surveys of the 

inflow and outflow streams of Cowanesque Lake since the early 1980's. The objective of these surveys is to 

identify possible detrimental effects as well as benefits of the reservoirs and to better understand the 

aquatic communities in the vicinity of the reservoirs at the present and over time. The U.S. Army Corps of 

Engineers and the U.S. Geological Survey jointly conducted a survey of the fish communities at 

Cowanesque River near Nelson, Pa. (inflow), and Cowanesque River near Lawrenceville, Pa. (outflow), in 

September 1998 to address community differences between reaches. A habitat assessment was conducted 

in accordance with the U.S. Environmental Protection Agency's Rapid Bioassessment Protocols to 

determine any possible habitat influence on fish communities located in these reaches.

The fish communities upstream and downstream of Cowanesque Lake are in good to fair condition; 

the Index of Biotic Integrity (IBI) scores are 4.3 and 3.8, respectively. An IBI developed for Maryland 

streams was used for the assessment because no IBI that is specifically applicable to Pennsylvania or New 

York is available, and the fauna in Maryland is more like that in Pennsylvania and New York than are 

fauna in Ohio and the Midwest, for which IBI's have been established, or the Northeast, where streams are 

species depauperate. The habitat conditions upstream and downstream were sub-optimal. These fish 

communities, however, were different; the Jaccard Coefficient was 0.32, and the Index of Similarity was 

0.48. Upstream, 11 species were collected; 22 were collected downstream. The Shannon Index for the 

upstream sampling site was 2.69 and for the downstream site was 3.36.

Upstream of the reservoir, the bottom substrate was bedrock, cobble, and boulder. The geomorphic 

channel unit of the reach was riffle and pool. The fish species collected upstream are typical of streams 

with bedrock and boulders. The boulders are used for cover and protection. Downstream of the reservoir, 

the bottom substrate was cobble and gravel, and the geomorphic channel unit also was riffle and pool. 

Vegetation and woody snags provided a diversity of cover for the fish. The species collected downstream 

are typical of those found in lakes and in slower, deeper waters of rivers with aquatic vegetation. 

Upstream and downstream, the habitats are different. These differences are reflected by the fish 

communities present in the two reaches. The influence of the dam on these communities cannot be fully 

addressed without historical data but the reaches have different habitat and fish-community composition.
INTRODUCTION

Biological surveys of streams in the vicinity of selected reservoirs were initiated in 1982 by the 

Baltimore District, U.S. Army Corps of Engineers (COE). The principal objectives of the surveys are to 

identify possible detrimental effects as well as benefits of the reservoirs, add to a database that was 

developed for monitoring the composition, abundance, diversity, and distribution of fishes over time, and 

provide a better understanding of the aquatic resources in the vicinity of the reservoirs.

The present study was a joint effort between the COE and the U.S. Geological Survey (USGS). An 

assessment of the habitat suitability for sustaining fish communities also was included in this study. The 

fish communities were sampled to determine community composition and to document any differences 

between the communities upstream and downstream of the reservoir.

Reaches were selected to correspond with existing COE macroinvertebrate reaches and previously 

sampled fish-community reaches. Each reach included a proportional representation of the available 

geomorphologic units for the stream. Two reaches, one upstream and one downstream of Cowanesque 

Dam, which was constructed in 1973 for the purpose of flood control (Ward, 1976), were chosen for the 

fish-community study (fig. 1). Release from the dam is through multilevel outlet works and over the 

spillway when flood levels are reached (Ward, 1976).

The upstream reach, Cowanesque River near Nelson, Pa. (latitude/longitude = 41°58'25"/77°14'44"), 

begins at the falls that flow into the reservoir and extends upstream 203 m (666 ft). The falls are a barrier 

that likely prevent fish migration from the reservoir into the upstream reach. The area sampled was 

approximately 2,934 m2 (31,687 ft2). The drainage area is 640 Ion2 (247 mi2). The geomorphic channel unit 

is riffle and pool. The reach bottom material is bedrock, cobble, and boulder. At the time of sampling, 

approximately 50 percent of the streambed appeared exposed following drought conditions. The left bank 

rises steeply; the flood plain is vegetated with a few trees and grasses. The right bank is a linear, gravel 

shoal that transitions into a thin riparian zone. The pH was 7.1, temperature was 21°C, and specific 

conductance was 403 uS/cm.

The downstream reach, Cowanesque River near Lawrenceville, Pa. (latitude/longitude = 

42000'07"/77°07'35"), is 150 m (495 ft) downstream of the State Route 15 bridge outside of Lawrenceville, 

Pa., and extends 150 m (495 ft) upstream ending below the bridge. The approximate area sampled was 

4,150 m2 (44,820 ft2). The drainage area is 744 km2 (299 mi2). The geomorphic channel unit is riffle and 

pool. Substrate in the reach is cobble and gravel. None of the streambed was exposed. The left side of the 

stream is mostly riffle; towards the top of the reach is a pooled area under the bridge. The right side of the 

stream has woody snags, algal beds, and aquatic vegetation. The banks are vegetated with trees and 

grasses. The pH was 6.7, temperature 19°C, and specific conductance was 206 uS/cm.
77° 15'00"

42° 00' 00"41° 57'30"

_ 

NEW YORK 

PENNSYLVANIA

EXPLANATION

SURVEYED STREAM REACH

77° 07' 30"

Lawrence

LOCATION OF STUDY AREA

0

0

1 2 MILES

1 2 KILOMETERS

PENNSYLVANIA

Figure 1 . Site location of reaches sampled for fish communities upstream and downstream of the Cowanesque Dam, Tioga County, Pa., 1998.
STUDY METHODS

The fish communities at the inflow and outflow of Cowanesque Lake were surveyed on September 

15 and 16,1998. These communities were characterized by the total number of species collected and the 

relative abundance of each species. Habitat was assessed and related to the fish communities found in 

each reach.

Fish Sampling

A Coffelt Mark-10 backpack electroshocker incorporating pulsed direct current was used to collect 

fish at each sampling reach. Both reaches were wadable. A five person crew was used in both reaches. The 

backpack electroshocker, an electrode, and a net was carried by one person. The other individuals on the 

crew netted the fish and put them in buckets. The upstream reach was covered with a single pass of 

4,406 seconds. To cover the downstream reach, two passes were conducted, requiring 5,244 seconds to 

complete. All passes were conducted in an upstream direction.

After each pass, the fish were placed in rubber tubs with aerators, sorted, and identified to species 

using texts to confirm identifications (Page and Burr, 1991). A maximum of 25 individuals per species were 

weighed (grams), measured for total and standard lengths (millimeters), and examined for external 

anomalies (Meador and others, 1993). After 25 individuals of a species were weighed and measured, the 

remaining fish were counted and mass weighed to the nearest gram. A summary of the fish data can be 

found in the Appendix. A few specimens were put in 10-percent buffered formaldehyde for a voucher 

collection and verification in the USGS laboratory in Lemoyne, Pa. At the downstream reach, the fish from 

the first pass were placed in a live cage away from the reach being shocked to protect these fish from 

further trauma. After both passes were completed, the fish not retained for voucher specimens were 

released back into the river.

Habitat Quantification

Habitat assessment was conducted according to the Rapid Bioassessment Protocols (RBP) (Barbour 

and others, 1997). The riffle and run prevalence data form was used. Twelve criteria were used to assess 

the quality of the fish habitat. Each criterion is rated on a score of 1 to 20. These scores were summed for a 

total habitat score. An average was then calculated and assessment was made on this averaged score. A 

score of 0-5 is poor, 6-10 is marginal, 11-15 is suboptimal, and 16-20 is optimal (Klemm and Lazorchak, 

1995). A reach with a higher habitat score should, theoretically, support a healthier fish community than a 

reach with a lower habitat score.

Data Analysis

The numbers of fish and their weights were totaled by species. The catch-per-unit-effort (CPUE) was 

calculated by dividing the number of fish collected by the total electroshocking time (Nielsen and Johnson, 

1983). CPUE was used to compare the number of fish collected at each reach for the amount of time used 

for the effort. A higher CPUE would show more fish in an area than a lower CPUE. The reach with the 

lower CPUE is typically considered to be more impaired than a reach with a higher CPUE (Nielsen and 

Johnson, 1983).
Four indices were generated to further assess the health of the fish communities found in these 

reaches. The Shannon Index (H') is a value that combines species richness and evenness where >3.99 can 

be considered non-impacted; 3.00-3.99, slightly impacted; 2.00-2.99, moderately impacted; and <2.00, 

severely impacted (Bode and others, 1993). This calculation gives one estimate of the health of the entire 

fish community in each reach. A Jaccard Coefficient of Similarity and an Index of Similarity (Klemm and 

others, 1990) measure community similarity using the species present in both reaches and those found 

only in one reach or the other. These index scores can range between 0.0 and 1.0, reaching 1.0 as the 

similarities between reaches increases (Plafkin and others, 1989). The fourth index is an Index of Biotic 

Integrity (IBI). The Maryland IBI for non-coastal streams (Roth and others, 1997) was used because 

Pennsylvania and New York do not have an IBI currently in place. The IBI score is used to measure the 

health of a fish community, taking into consideration the number of native species, feeding habits of the 

species present, and their tolerance or intolerance to water pollution and sediment. The first two metrics 

for the IBI, number of native species and number of benthic species, are adjusted for watershed areas using 

the formula in Roth and others (1997). A numeric scale where 1.0-1.9 is very poor, 2.0-2.9 is poor, 3.0-3.9 is 

fair, and 4.0-5.0 is good (Roth and others, 1997) is used to show the health of the community. These indices, 

in combination with the CPUE, are used to show any differences between the fish communities in the 

reaches surveyed, to determine if the fish communities show any impairment, and to aid in assessing if 

differences seen in the communities are related to the impoundment.

When this work began, there was an understanding that a statewide IBI would be available by the 

time data analyses were initiated. Unfortunately, this was not the case. Because the state of New York also 

did not have an IBI in place, the well researched and highly tested model developed by the Maryland 

Biological Stream Survey (MBSS) was selected. The use of regional IBI's has been endorsed by Miller and 

others (1988) and use of regional reference sites by Hughes and others (1986). These studies indicate that 

when geographically specific IBI's or reference conditions are not available, reasonably comparative 

conditions from ecologically similar areas may be used.

Although somewhat geographically distant, the fish faunal assemblages of Maryland were thought 

to better represent the Susquehanna River Basin drainage than the species depauperate northeastern 

region. The Northern Highland ecoregion is common to both the study area and the area where the 

metrics were developed. Many metrics included in all multi-metric scoring systems seem to have 4-5 core 

metrics that explain much of the classification efficiency of the index. The remaining metrics add 

redundancy to insure a strong mathematical signal is developed. For example, 4 of the 12 metrics in the 

original IBI (Karr, 1981) respond to sediment.

The Maryland area where the IBI was developed may not be locally specific, but it does include the 

historical unit of the Susquehanna River drainage. The IBI also includes many sites, covers many species 

collected in the study area, and very importantly is adjusted for basin size. It is the logical alternative to 

use under these conditions.
FISH-COMMUNITY COMPOSITION

A total of 11 species were collected upstream of Cowanesque Lake with a calculated CPUE of 6.7 

(table 1), an H' of 2.69 (table 1), an IBI of 4.3 (table 2), and a habitat score of 151 (table 3). A total of 22 

species were collected downstream with a calculated CPUE of 7.4 (table 1), an H' of 3.36 (table 1), an IBI of 

3.8 (table 2), and a habitat score of 168 (table 3). A Jaccard Coefficient of Similarity of 0.32 and an Index of 

Similarity of 0.48 showed these communities are different. Detailed information about the species is in the 

Appendix. The sculpins were only identified to genus because of the difficulty in differentiating among 

sculpin species in the field.

Table 1. Taxa list, number of individuals, and total and average weights by species for fish communities upstream and 

downstream of Cowanesque Dam, Pa., 1998

[ , not collected in this sample]

Upstream reach

Species name

Central stoneroller, Campostoma anomalum

Spotfin shiner, Cyprinella spiloptera

Common carp, Cyprinus carpio

Cutlips minnow, Exoglossum maxillingua

River chub, Nocomis micropogon

Comely shiner, Notropis amoenus

Spottail shiner, Notropis hudsonius

Bluntnose minnow, Pimephales notatus

Blacknose dace, Rhinichthys atratulus

Longnose dace, Rhinichthys cataractae

Creek chub, Semotilus atromaculatus

Fallfish, Semotilus corporalis

White sucker, Catostomus commersoni

Northern hog sucker, Hypentelium nigricans

Margined madtom, Noturus insignis

Chain pickerel, Esox niger

Sculpin, Cottus spp.

Rock bass, Ambloplites rupestris

Pumpkinseed, Lepomis gibbosus

Smallmouth bass, Micropterus dolomieu

Black crappie, Pomoxis nigromaculatus

Tessellated darter, Etheostoma olmstedi

Banded darter, Etheostoma zonale

Yellow perch, Perca flavescens

Shield darter, Perca peltata

Totals

Total number of species

CPUE (number of individuals per shocking 

time in minutes)

H' (Shannon Index)

Numbers of 

individuals

9

152

2

36

4

55

12

27

10

128

57

492

11

6.7

2.69

Species 

total weight, 

in grams

131

1,060

27

90

9

1,441

1,536

232

113

1,687

92

6,418

Downstream reach

Number of 

individuals

14

1

5

1

1

92

6

46

1

14

111

1

1

3

19

50

1

1

119

27

53

79

646

22

7.4

3.36

Species 

total weight, 

in grams

117

2

6,296

4

3

221

12

231

4

73

30,146

2

22

34

1,190

426

105

21

301

68

428

296

40,002
Table 2. IBI score for fish communities upstream and downstream of Cowanesque Dam, Pa., 1998 

[4.0-5.0, good; 3.0-3.9, fair; 2.0-2.9, poor; 1.0-1.9, very poor (Roth and others, 1997)]

IBI metric 1

Number of native species (adjusted value)

Number of benthic species (adjusted value)

Percent tolerant individuals

Percent abundance of dominant species

Percent generalists, omnivores, and invertivores

Percent insectivores

Number of individuals per square meter

Percent lithophilic spawners

Average IBI score

Upstream reach

5

5

5

5

3

5

1

5

4.3

Downstream reach

5

5

5

5

1

3

1

5

3.8

1 Roth and others, 1997.

Table 3. Habitat assessment upstream and downstream of Cowanesque Dam, Pa., 1998 

[0-5, poor; 6-10, marginal 11-15, suboptimal, 16-20, optimal]

Habitat parameter1

Instream fish cover

Epifaunal substrate

Embeddedness

Velocity/depth regimes

Channel alteration

Sediment deposition

Frequency of riffles

Channel flow status

Condition of banks

Bank vegetative protection

Grazing or other disruptive pressure

Riparian vegetative zone width

Total score

Average score

Upstream reach

11

15

17

17

10

14

15

8

12

12

10

10

151

13

Downstream reach

12

10

15

15

15

15

6

17

18

18

15

12

168

14

1 Klemm and Lazorchak, 1995.
Upstream Reach

The fish community in the reach upstream of the reservoir is in good condition as shown by the IBI. 

The community is moderately impacted according to the H' score. The habitat is suboptimal and of lesser 

quality than the reach downstream of the reservoir. Banks are less stable, which corresponds with the high 

frequency of riffles and higher velocities in the reach (table 3). The species collected in this reach are 

typically found in areas with boulders and little vegetation (Cooper, 1983; Page and Burr, 1991; Rohde and 

others, 1994; Smith, 1985). There is less embeddedness in this reach than downstream, and there is aquatic 

vegetation downstream that is not seen in the upstream reach. Vegetation cannot grow on bedrock and 

areas where little sediment covers the stream bottom.

The dominant species collected in this reach was cutlips minnow. This species is reported to remove 

the eyes of other fish (Smith, 1985; Jenkins and Burkhead, 1994). This behavior seems to be brought on by 

crowding and is a territorial response Qenkins and Burkhead, 1994). Observation of the rock bass and 

smallmouth bass in this reach showed greater than 50 percent of these fish were missing at least one eye. 

Blackspot, parasites, or leeches were observed on 7 of the 11 species in this reach. These anomalies show an 

inconsistent relation with water quality and are therefore recorded but not typically used in assessment of 

water quality when using IBI scores (Simon, 1999).

Cutlips minnow, river chub, and northern hog sucker were collected upstream but not downstream 

of the dam. These species are typical in clear waters with gravel, rubble, and boulder substrate (Rohde and 

others, 1994). The northern hog sucker is considered a clean-stream indicator (Cooper, 1983) and is rarely 

found in areas with heavy siltation, pollution, or channel modification (Smith, 1979; Trautman, 1981). The 

CPUE and the diversity of the upstream reach were lower than that of the reach downstream of the 

reservoir.

Downstream Reach

The fish community in this reach is in fair condition as shown by the IBI. The H' score indicates this 

community is more diverse than the community in the upstream reach and is only slightly impacted. The 

CPUE was higher here than upstream of the reservoir. Twenty-two species were collected in this reach; 14 

of these species were not collected in the upstream reach. The habitat was suboptimal but ranked higher 

than the upstream habitat. The frequency of riffles was the lowest scoring downstream habitat criterion 

(table 3). This reach displayed a variety of habitats, including pooled areas under the bridge and around 

woody snags, and aquatic vegetation along the left edge of water, that were not found upstream.

Of the 14 species collected exclusively downstream, 5 of these had a relative abundance of 5 percent 

or greater bluntnose minnow, pumpkinseed, banded darter, yellow perch, and shield darter. These 

species are typical near vegetative cover Qenkins and Burkhead, 1994; and Page and Burr, 1991). Bluntnose 

minnow, pumpkinseed, and yellow perch are typical in quiet waters of pools and backwaters Qenkins and 

Burkhead, 1994; Rohde and others, 1994), and yellow perch also are intolerant of pollutants and siltation 

(Rohde and others, 1994). Banded and shield darters are typical of moderate gradient streams with riffles 

and runs, areas without heavy siltation, and around submerged aquatic vegetation (Cooper, 1983; Page 

and Burr, 1991). By regulating flow out of the dams, normal fluctuations of flow and temperature are 

removed in downstream reaches, which promotes the growth of aquatic vegetation (Hynes, 1970) with 

which these fish are commonly associated. Dams also allow for suspended sediment to settle out of the 

water column and improve the clarity of streams downstream (Hynes, 1970). However, little difference 

was seen in embeddedness or sediment deposition between the two reaches (table 3). Of the 14 exclusive 

species, 9 of these species are collected from impoundments as well as streams (Cooper, 1983; Jenkins and 

Burkhead, 1994; Page and Burr, 1991; Rohde and others, 1994; Smith, 1985). Anomalies were observed in 

less than 10 percent of the fish in the downstream reach.
The downstream reach was wider than the upstream reach and no bedrock was present. However, 

there were pools, aquatic vegetation, and woody snags, along with riffle and run areas that provide 

multiple habitats where a greater diversity of fish species survive. The downstream community has a 

lower IBI than upstream, but H' showed the community downstream as being more diverse. More species 

were collected downstream (22) than upstream (11) of the reservoir. This accounts for the higher H' score. 

The lower IBI score of the downstream reach is a consequence of the lower percentage of generalists, 

omnivores, invertivores, and insectivores there. These were the only differences between the IBI scores of 

the reaches.

The Jaccard Coefficient and the Index of Similarity showed the upstream and downstream 

communities are different. Northern hog sucker and yellow perch are suggestive of good water quality; 

one is present upstream and one downstream of the dam. Some species present downstream exhibit a 

preference for pooled rivers and lakes. The reach sampled below the dam had more pooled area than the 

upstream reach where these lake species may be able to exist. Some of these species could be from the 

reservoir and survive in the stream because dams can alter riverine environments and change them to 

lacustrine ones (Jenkins and Burkhead, 1994). A species list of the fish collected in the reservoir would be 

needed to make an accurate assessment.

The downstream reach of the Cowanesque River has more pooled areas than the upstream reach, 

where the water is slower moving and deeper than found in riffle areas. Different species of fish inhabit 

these larger, deeper pools than the riffles. Flow in the downstream reach of the dam is augmented during 

summer months to provide the towns downstream with an adequate drinking water supply (U.S. Army 

Corps of Engineers, website accessed May 4,1999). Water temperature decreases by 2°C from upstream to 

downstream of the dam. The pH was 7.1 upstream and 6.7 downstream. Temperature and pH of the two 

reaches cannot explain the community differences seen. The water-quality property that shows the most 

significant change is specific conductance. The change was from 403 to 206 [iS/cm, upstream and 

downstream, respectively. The differences seen in the fish community appear to be related to the 

previously discussed habitat and not to differences in water quality.

The dam was built to protect the towns downstream from periodic flooding, to augment flow of the 

Cowanesque River, and to provide an adequate water supply for the towns along the river (U.S. Army 

Corps of Engineers, Civil Works Project Information, website accessed May 4,1999). The uniform flow that 

a dam provides is typically not favorable to native fishes that need high spring flows for spawning and can 

survive summer low-flow conditions (Moyle, 1976; Baltz and Moyle, 1993; Strange and others, 1992). The 

drought effects noted in the upstream reach were not noted downstream of the dam because of the flow 

augmentation. It has been documented that the flow from a dam can prevent flooding and drought 

conditions downstream of the dam but cannot affect the upstream reaches of a river (Hynes, 1970).

The community downstream consists of a greater number of generalist feeding species than are 

found upstream. This is an indication that habitat types are diverse (Halliwell and others, 1999) and can be 

characteristic of degraded habitat (Fausch and others, 1990). More species can inhabit the downstream 

reach because of the variety in habitat types. Only a few fish species can live and reproduce in the riffle 

habitat found in the upstream reach, while in the varied habitats downstream, many more species can live 

and reproduce. The generalist feeding fish species are typically found downstream of dams because dams 

retain the normal energy source of the stream by trapping coarse and fine particulate organic matter in the 

reservoir (Vannote and others, 1980). This energy source is needed for native, specialist species to exist. 

Both the dam and habitat differences can affect the fish-community structure downstream and cause the 

native community, which may have been similar to the upstream community, to be replaced.
Whether or not some habitat features, such as stream width and depth, were always different or 

were changed after the dam was built must still be addressed with comparison to pre-impoundment 

studies of the fish communities and habitat. More in-depth analysis of the historical data may give clues to 

why these communities are different. This comparison is outside the scope of the report.

SUMMARY

Two reaches of the Cowanesque River, which flows in and out of Cowanesque Lake, were studied to 

evaluate the current status of fish communities in the vicinity of the reservoir. The study was conducted to 

determine the similarities and differences in fish communities above and below the reservoir in 1999 and 

to identify any possible effects the dam could have on these communities.

A survey conducted on September 15 and 16,1998, showed the fish communities to be in good 

condition upstream and fair condition downstream of the reservoir based on IBI scores. The downstream 

community had twice as many species as upstream, a higher Shannon Index, and a higher CPUE. The fish 

downstream are more generalist feeders; those upstream are more insectivorous feeders. This would make 

the IBI upstream higher. The other individual IBI metrics were the same for both reaches.

The fish communities in the two reaches surveyed were different according to the Jaccard 

Coefficient and the Index of Similarity. The species downstream are typical in reservoirs and larger, slower 

moving waters and in areas where there is submerged aquatic vegetation. The upstream species are typical 

in faster moving waters and in waters with little or no aquatic vegetation.

Instream habitat differed significantly between the upstream and downstream reaches. The 

geomorphic channel unit upstream of the reservoir is bedrock riffles and cobble, boulder runs; the 

geomorphic channel unit downstream was riffle, run, and pool with a predominantly cobble and gravel 

stream bottom. The downstream reach was wider and other streams flowed into the segment of stream 

between the two reaches. These habitat differences can influence the structure of the fish communities seen 

in the reaches.

Historically, the communities in these reaches may have been different because of naturally 

occurring habitat differences, the falls upstream, and the input from the other streams entering the river 

segment between the two sampling sites. Alternatively, the regulation of the flow from the dam may have 

altered the downstream habitat. This can not be determined from this survey alone.

10
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12
APPENDIX

13
Study Unit: COE

Station Name: Cowanesque River near Nelson, Pa.

Lat/Long: 41 °58'25777°14'44"

County: Tioga

pH: 7.1, Temperature: 21.0°C, Conductance: 403 nS/cm

Investigators: Bilger, Brightbill, Kulp, Pisarski, Barlock

Date of Collection: 09/16/1998

# of Species at Reach: 11

Sampling Gear Code: backpack 

Time/Pass(sec7min.): 4,406/73

Species name

Central stoneroller, Campostoma anomalum

Cutlips minnow, Exoglossum maxillingua

River chub, Nocomis micropogon

Longnose dace, Rhinichthys cataractae

Creek chub, Semotilus atromaculatus

White sucker, Catostomus commersoni

Northern hog sucker, Hypentelium nigricans

Margined madtom, Noturus insignis

Rockbass, Ambloplites rupestris

Smallmouth bass, Micropterus dolomieu

Tessellated darter, Etheostoma olmstedi

Totals for reach:

Total number Percent of 

of fish per total number 

species of fish

9

152

2

36

4

55

12

27

10

128

57

492

1.8

30.8

.4

7.3

1.0

11.2

2.4

5.5

2.0

26.0

11.6

Total weight 

per species 

(grams)

131

1,060

27

90

9

1,441

1,536

232

113

1,687

92

6,418

Percent 

total 

weight

2.0

16.5

.4

1.4

.1

22.5

23.9

3.6

1.8

26.2

1.4

Average 

weight 

(grams)

15

7

14

3

2

26

128

9

11

13

2

Range of 

weights 

(grams)

4-26

1-23

8-19

1-12

1-3

4-186

4-612

2-43

2-49

3-104

1-4

Average 

total length 

(millimeters)

100

79

105

60

49

135

176

83

67

109

51

R

tot

/ 

(m

v 

Reported anomalies: central stoneroller -11% 

blackspot, 12% with fin erosion; creek chub

with blackspot; cutlips minnow - 4% with blackspot, 8% with fin erosion; river chub - 50% with bl

 100% with blackspot; margined madtom - 28% with parasites; rockbass -10% with leeches
Study Unit: COE

Station Name: Cowanesque River near Lawrenceville, Pa.

Lat/Long: 42000'07"/77007'35"

County: Tioga

pH: 6.7, Temperature: 19°C, Conductance: 206 |^S/cm

Investigators: Bilger, Brightbill, Kulp, Pisarski, Barlock

Date of Collection: 09/15/1998

# of Species at Reach: 22

Sampling Gear Code: backpack 

Time/Pass(sec./min.): 5,244/87

Species name

Central stoneroller, Campostoma anomalum

Spotfin shiner, Cyprinella spiloptera

Common carp, Cyprinus carpio

Comely shiner, Notropis amoenus

Spottail shiner, Notropis hudsonius

Bluntnose minnow, Pimephales notatus

Blacknose dace, Rhinichthys atratulus

Longnose dace, Rhinichthys cataractae

Creek chub, Semotilus atromaculatus

Fallfish, Semotilus corporalis

White sucker, Catostomus commersoni

Margined madtom, Noturus insignis

Chain pickerel, Esox niger

Sculpin, Cottus sp.

Rockbass, Ambloplites rupestris

Pumpkinseed, Lepomis gibbosus

Smallmouth bass, Micropterus dolomieu

Black crappie, Pomoxis nigromaculatus

Tessellated darter, Etheostoma olmstedi

Banded darter, Etheostoma zonale

Yellow perch, Percaflavescens

Shield darter, Perca peltata

Totals for reach:

Total number 

of fish per 

species

14

1

5

1

1

92

6

46

1

14

111

1

1

3

19

50

1

1

119

27

53

79

646

Percent of 

total number 

of fish

2.2

.2

.8

.2

.2

14.2

.9

7.1

.2

2.2

17.2

.2

.2

.5

2.9

7.7

.2

.2

18.4

4.2

8.2

12.2

Total weight 

per species 

(grams)

117

2

6,296

4

3

221

12

231

4

73

30,146

2

22

34

1,190

426

105

21

301

68

428

296

40,002

Percent 

total 

weight

0.292

.005

15.7

.010

.007

.552

.030

.577

.010

.182

75.3

.005

.055

.085

2.97

1.06

.262

.052

.752

.170

1.06

.740

Average 

weight 

(grams)

8

2

1,259

4

3

2

2

5

4

5

272

2

22

11

63

9

105

21

3

3

8

4

Range of Average R

weights total length tot

(grams) (millimeters) (m

1-21

2

3-1,709

4

3

1-6

1-4

2-8

4

1-16

5-782

2

22

6-16

23-138

3-21

105

21

2-5

1-4

3-42

3-6

83

66

393

83

70

55

55

79

77

74

304

59

161

91

140

73

204

117

67

44

77

72

Reported anomalies: white sucker - 4% with lesions; pumpkinseed - 4% with leeches