U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2020–5021

Prepared in cooperation with the South Carolina Department of Transportation

Effects of Box Culverts on Stream 

Habitat, Channel Morphology, and Fish 

and Macroinvertebrate Communities at 

Selected Sites in South Carolina, 2016–18
Front cover: Left, Box culvert on Enoree Creek at South Carolina Highway 49, near Cross Anchor, S.C. Photograph by Jeff Riley. 

Right, Sampling crew collecting fish with backpack electrofisher at box culvert Sadler Swamp on SC 122 near St. Matthews, S.C. 

(Left to right: Karen Beaulieu, Steve Walsh, Jeff Riley, Ryan Rasmussen.) Photograph by Alan Cressler, U.S. Geological Survey. 

Back cover: Photographs of box culverts in South Carolina. Photographs by Jeff Riley. 

Top, Tributary to Alison Creek at SC 236, near Clover, S.C. 

Middle, Bishop Branch at SC 49, near Cross Anchor, S.C. 

Bottom, Kennedy Creek at Unites States Highway 176, near Pacolet, S.C.
Effects of Box Culverts on Stream 

Habitat, Channel Morphology, and Fish 

and Macroinvertebrate Communities at 

Selected Sites in South Carolina, 2016–18

By Jeffrey W. Riley, Karen M. Beaulieu, Stephen J. Walsh, and 

Celeste A. Journey

Prepared in cooperation with the South Carolina Department of Transportation

Scientific Investigations Report 2020–5021

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

DAVID BERNHARDT, Secretary

U.S. Geological Survey

James F. Reilly II, Director

U.S. Geological Survey, Reston, Virginia: 2020

For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, 

natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, and publications, visit 

https://store.usgs.gov/.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the 

U.S. Government.

Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials 

as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner.

Suggested citation:

Riley, J.W., Beaulieu, K.M., Walsh, S.J., and Journey, C.A., 2020, Effects of box culverts on stream habitat, 

channel morphology, and fish and macroinvertebrate communities at selected sites in South Carolina, 2016–18: 

U.S. Geological Survey Scientific Investigations Report 2020–5021, 51 p., https://doi.org/ 10.3133/ sir20205021.

ISSN 2328-0328 (online)
iii

Acknowledgments

The complexity of the investigation required interagency cooperation in addition to individual 

contributions. The authors thank the staff of the South Carolina Department of Transportation 

(SCDOT), particularly Jeff Siceloff, Assistant Project Manager; Terry Swygert, Research 

Engineer; and Meredith Heaps, Research Program Manager. This work would not have 

been possible without the field assistance of Andy Caldwell, Jimmy Clark, Kevin Conlon, 

Alan Cressler, Fred Falls, Wladmir Guimaraes, Doug Nagle, and Ryan Rasmussen from the 

U.S. Geological Survey (USGS), to whom we are grateful. The authors also thank USGS 

colleagues James Coles and Alex Covert for their thoughtful reviews and constructive 

suggestions. Additionally, we would like to thank the landowners who allowed us access to 

their property.

v

Contents

Acknowledgments........................................................................................................................................iii

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

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

Purpose and Scope ..............................................................................................................................2

Description of Study Area ...................................................................................................................2

Previous Investigations........................................................................................................................5

Approach and Methods................................................................................................................................5

Site Selection.........................................................................................................................................5

Reach Layout .........................................................................................................................................6

Habitat and Geomorphic Assessments .............................................................................................6

Fish Community Assessments ............................................................................................................8

Macroinvertebrate Community Assessments .................................................................................9

Data Analysis.........................................................................................................................................9

Habitat and Geomorphic Characterization ..............................................................................................10

Geomorphic Channel Units ...............................................................................................................10

Channel Morphology ..........................................................................................................................12

Bed-Sediment Characteristics and Large Woody Debris ............................................................18

Culvert Slope........................................................................................................................................18

Ratio of Culvert Width to Bankfull Width ........................................................................................18

Fish Community Characterization .............................................................................................................21

Macroinvertebrate Community Characterization ...................................................................................31

Role of Culverts in Shaping Channel Morphology, Aquatic Habitat, and 

Biotic Community Structure .........................................................................................................38

Placing Current Geomorphic Settings in Perspective ..................................................................38

Effects of Box Culverts on Habitat and Biotic Communities ........................................................39

Implications for Future Culvert Design and Mitigation .................................................................41

Conclusions...................................................................................................................................................41

References Cited..........................................................................................................................................42

Appendix 1. Macroinvertebrate Metrics and Sample Classifications ............................................47

Reference Cited............................................................................................................................................47

Figures

1. Map showing locations of selected South Carolina Department of 

Transportation (SCDOT) culverts and physiographic provinces in South Carolina ...........3

2. Diagram of reaches, transects, and zones sampled in streams at selected 

culvert sites in South Carolina, 2016–18 ...................................................................................7

3. Annotated photograph showing the channel levels, or elevations, where 

channel morphology measurements were made ....................................................................8

4. Graph showing habitat complexity, as defined by the number of geomorphic 

channel units (GCUs) per reach, at selected culvert sites in South Carolina ..................11

5. Boxplots showing the distribution of channel-full cross-sectional area z-scores 

for upstream and downstream reaches at selected culvert sites in South 

Carolina, 2016–18 ........................................................................................................................13
vi

6. Boxplots showing the distribution of channel-full depth z-scores for upstream 

and downstream reaches at selected culvert sites in South Carolina, 2016–18 .............15

7. Boxplots showing the distribution of channel-full width-to-depth ratio 

for upstream and downstream reaches at selected culvert sites in South 

Carolina, 2016–18 ........................................................................................................................17

8. Graphs showing particle-size cumulative frequency distributions within each 

zone for the 14 Piedmont study sites .......................................................................................19

9. Boxplots showing the distribution of large woody debris volume, aggregated to 

the reach level, at selected culvert locations in South Carolina, 2016–18 ........................20

10. Graph showing the slope of culvert bottom and stream thalweg in upstream 

and downstream reaches at selected culvert sites in South Carolina, 2016–18 .............21

11. Graph showing Shannon-Wiener diversity index values for fish communities 

sampled at selected culvert sites in South Carolina, 2016–18 ............................................24

12. Hierarchical clustering dendrogram of selected culvert sites in South 

Carolina, with upstream and downstream reaches combined, created by 

using group-averaging Bray-Curtis similarities calculated from square-root 

transformed catch per unit effort data for fish samples ......................................................25

13. Two-dimensional (2D) nonmetric multidimensional scaling (nMDS) plot of fish 

catch per unit effort data for selected culvert sites in South Carolina factored 

by physiographic province; upstream and downstream reaches are combined 

for each site .................................................................................................................................26

14. Bar graph showing the taxonomic richness of fish species collected at 

selected culvert sites in South Carolina .................................................................................27

15. Hierarchical clustering dendrogram of downstream (dn) and upstream 

(up) reaches at selected culvert sites in South Carolina, created by using 

group-averaging Bray-Curtis similarities calculated from square-root 

transformed catch per unit effort data for fish samples ......................................................29

16. Two-dimensional (2D) nonmetric multidimensional scaling (nMDS) plot of 

downstream (dn) and upstream (up) reaches for selected culvert sites in South 

Carolina ........................................................................................................................................30

17. Two-dimensional (2D) nonmetric multidimensional scaling (nMDS) plots of 

macroinvertebrate assemblage data for samples collected in four zones at 

selected culvert sites in South Carolina .................................................................................32

18. Hierarchical clustering dendrograms of samples collected in four zones at 

selected culvert sites in South Carolina, created by using group-averaging 

Bray-Curtis similarities calculated from square-root transformed 

macroinvertebrate abundance data ........................................................................................34

Tables

1. Selected culvert sites in South Carolina that were assessed for morphological 

and ecological effects, 2016–18 .................................................................................................4

2. Habitat and geomorphic features measured in streams at selected culvert sites 

in South Carolina, 2016–18; associated method references; and any deviations 

from the cited methods ................................................................................................................7

3. Results of nonparametric tests on habitat complexity measured in upstream 

(US) and downstream (DS) reaches at selected culvert sites in South 

Carolina, 2016–18 ........................................................................................................................12
vii

4. Results of nonparametric tests on mean channel-full cross-sectional area 

z-scores for upstream (US) and downstream (DS) reaches at selected culvert 

sites in South Carolina, 2016–18 ...............................................................................................14

5. Results of nonparametric tests on mean channel-full depth z-scores for 

upstream (US) and downstream (DS) reaches at selected culvert sites in South 

Carolina, 2016–18 ........................................................................................................................16

6. Fish species collected at selected culvert sites in South Carolina, 2016–18, 

physiographic province, number of sites, number of reaches where each 

species was collected, number of specimens, and percent composition of 

total sample .................................................................................................................................22

7. Results of nonparametric tests of fish species richness between downstream 

and upstream reaches by physiographic province ..............................................................28

8. Combinations of mean reach habitat variables that best match the fish 

community structure as measured by Spearman rank correlation test using 

the Bio-Env + Stepwise (BEST) routine in Plymouth Routines in Multivariate 

Ecological Research (PRIMER) ................................................................................................30

9. Combinations of macroinvertebrate metrics that best match the 

macroinvertebrate community structure as measured by Spearman rank 

correlation test using the Bio-Env + Stepwise (BEST) routine in Plymouth 

Routines in Multivariate Ecological Research (PRIMER) ....................................................37

10. Combinations of mean zone habitat variables that best match the 

macroinvertebrate community structure as measured by Spearman rank 

correlation test using the Bio-Env + Stepwise (BEST) routine in Plymouth 

Routines in Multivariate Ecological Research (PRIMER) ....................................................38

Conversion Factors

International System of Units to U.S. customary units

Multiply By To obtain

Length

micrometer (μm) 0.00003937 inch (in.)

millimeter (mm) 0.03937 inch (in.)

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.281 foot (ft)

meter (m) 1.094 yard (yd)

Area

square meter (m2) 10.76 square foot (ft2)

square kilometer (km2) 0.3861 square mile (mi2)

Volume

cubic meter (m3) 35.31 cubic foot (ft3)

cubic meter (m3) 1.308 cubic yard (yd3)

Flow rate

meter per second (m/s) 3.281 foot per second (ft/s)
viii

Datum

Elevation, as used in this report, refers to distance above the vertical datum.

Abbreviations

2D two dimensional

3D three dimensional

ANOSIM analysis of similarities

BEST Bio-Env + Stepwise

C/f catch per unit effort

GCU geomorphic channel unit

LWD large woody debris

nMDS nonmetric multidimensional scaling

PRIMER Plymouth Routines in Multivariate Ecological Research

RI recurrence interval

SCDHEC South Carolina Department of Health and Environmental Control

SCDOT South Carolina Department of Transportation

SIMPROF similarity profile

S–W Shannon-Wiener diversity index

USACE U.S. Army Corps of Engineers

USGS U.S. Geological Survey
Effects of Box Culverts on Stream 

Habitat, Channel Morphology, and 

Fish and Macroinvertebrate Communities 

at Selected Sites in South Carolina, 2016–18

By Jeffrey W. Riley, Karen M. Beaulieu, Stephen J. Walsh, and Celeste A. Journey

Abstract

Much attention has been placed on the role that 

under-roadway culverts may have in inhibiting upstream 

fish movement because of altered hydrology and unsuitable 

conditions for accessing or swimming through the culvert. 

Other culvert effects related to habitat alterations or 

disturbance to macroinvertebrate communities have received 

relatively little attention. Entities responsible for culverts or 

other stream crossing structures are required to follow the 

U.S. Army Corps of Engineers guidelines for compensatory 

mitigation should any disturbance result from an engineering 

activity. One factor considered in the scoring of mitigation 

requirements is culvert length. Except for shading a longer 

length of stream, it is unknown whether longer culverts 

result in greater disturbance to stream habitat or the biotic 

communities than shorter culverts. The U.S. Geological 

Survey, in cooperation with the South Carolina Department 

of Transportation, evaluated the role of culverts in altering 

physical habitat and community structure of fish and 

macroinvertebrates at 20 sites in South Carolina. Culvert sites 

were categorized by length (either greater than 30.5 meters or 

less than or equal to 30.5 meters) and physiographic province 

(Piedmont or Upper Coastal Plain). This study design allowed 

for a regional assessment to determine if culverts may have 

different effects on habitat and biotic communities in different 

physical settings. The results indicated considerable variation 

in physical habitat characteristics within and among the 

culvert sites from all categories. A consistent finding was that 

channel cross-sectional area tended to increase in reaches 

downstream from culverts in the Upper Coastal Plain. The 

primary dimension of change was vertical, that is, incision 

of the streambed. This change, however, did not seem to 

coincide with a deleterious effect on the fish community. 

Increased habitat complexity and greater taxonomic richness 

were observed at most sites with downstream incision. 

Macroinvertebrate communities were highly variable and did 

not tend to cluster along any of the culvert categories, which 

may reflect the variability of microhabitats within each site. 

In contrast, fish communities were largely segregated by 

physiographic province but did not show any other significant 

clustering on the basis of upstream or downstream reach 

or culvert length. Given the small within-group sample 

size, extrapolation of results should be done carefully, 

acknowledging the physiographic and group characteristics.

Introduction

Culverts are ubiquitous features on the modern landscape 

and are especially prevalent where roadways traverse hilly 

topography with numerous low-order streams and swales. In 

South Carolina, there are more than 9,000 culverts of varying 

types and sizes. Research on the ecological effects of culverts 

has been relatively limited, such as studies that evaluated 

the role of substandard culverts in inhibiting fish movement 

because of culvert outlets perched above the streambed, high 

velocities caused by under-sized culverts, and shallow water 

depths (Gibson and others, 2005; Kemp and Williams, 2008; 

Evans and others, 2015; Birnie-Gauvin and others, 2019; 

Johnson and others, 2019). There is a general need for more 

detailed investigation on the effects of culverts on aquatic 

environments to assist agencies charged with assessing and 

mitigating deleterious effects to stream ecosystems from 

engineering activities.

Culverts may affect habitats and associated biota 

directly by interrupting stream connectivity or by altering 

localized stream velocity and hydraulics. An issue that has 

received considerable attention, albeit primarily at bridge 

locations, is contraction scour (Richardson and Richardson, 

1999). Contraction scour results when the natural flow 

area of a stream channel is reduced or constricted and the 

floodplain is blocked by the roadway. This type of scour is 

especially relevant to culverts because they may constrict 

the cross-sectional stream area and, with an immobile bed 

(unlike with bridges), energy may be further increased and 

transferred to the channel below the culvert outlet. The bed 

and banks can be eroded when water exits the culvert with 

excessive velocity, resulting in effects to channel stability, 

aquatic habitat, and associated biota (Merrill and Gregory, 
2 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

2004; Merrill, 2005; Khan and Colbo, 2008). Bouska and 

others (2010) noted that in Kansas prairie streams, bankfull 

depths and width-to-depth ratios were lower upstream from 

box culverts compared to downstream, possibly due to 

culvert-induced scour and incision. In addition to constricting 

the channel, culverts may also be installed with a slope that 

exceeds that of the prevailing streambed. Steep culvert slopes 

can have similar effects as constriction but may be even more 

disruptive because the steeper slope leads to higher water 

velocities, increasing scour potential even during lower flow 

conditions. For both constricted channels and steep culvert 

slopes, instream habitat and biota may be directly affected by 

the increased velocity and associated stream power that can 

erode and transport sediment. Increased energy over a limited 

longitudinal scale may interrupt sediment continuity, large 

wood transport, and general habitat conditions.

The South Carolina Department of Health and 

Environmental Control (SCDHEC) requires that the South 

Carolina Department of Transportation (SCDOT) evaluate the 

potential effects of culvert installations on streams by using 

the U.S. Army Corps of Engineers (USACE) guidelines for 

compensatory mitigation (U.S. Army Corps of Engineers, 

2010). These guidelines set numerical ratings for assessing 

potential effects related to culvert construction and installation. 

One of the factors considered is the culvert length class: 

(1) less than or equal to 30.5 meters (m) or (2) greater than 

30.5 m, with culverts longer than 30.5 m (referred to as 

“pipes”) assigned a higher rating, suggesting greater effects on 

streams. These ratings do not consider additional factors such 

as culvert size, culvert type, or site-specific monitoring data. If 

a stream is affected by culvert installation, then compensatory 

mitigation requires some form of restoration or enhancement 

action that may include stream channel restoration, bank 

stabilization, in-stream habitat recovery, or structure 

removal. Restoration activities are designed to improve 

ecological conditions, including habitat quality, water quality, 

and biological and morphological integrity. The USACE 

assessments, however, provide limited data to quantify the 

actual effects of culverts on the ecological conditions of 

streams and the degree of restoration that would be necessary 

to achieve targeted conditions. Prior to selection of restoration 

strategies, additional assessments would be required to 

understand (1) the changes in geomorphology and habitat of 

the natural streams associated with the construction of culverts 

at highways and roads and (2) the effects of those changes, if 

any, on the biological community within the streams.

Purpose and Scope

The U.S. Geological Survey (USGS), in cooperation 

with the SCDOT, investigated the effects of box culverts on 

stream ecosystems in the Piedmont and Upper Coastal Plain 

of South Carolina from 2016 to 2018. This report describes 

the results of the investigation to provide the SCDOT with 

scientific information to help guide future culvert design 

and mitigation. The objective of this study was to evaluate 

whether culverts alter stream morphology, habitat, and biotic 

communities. Furthermore, the study sought to examine how 

culvert effects, if any, varied by physiographic province and 

culvert length category (as defined by the USACE guidelines 

for compensatory mitigation assessments; U.S. Army Corps of 

Engineers, 2010). Thus, a primary intent of this investigation 

was to evaluate sites by culvert length. We hypothesized that 

long culverts (greater than 30.5 m) may have more adverse 

effects on stream ecology than short culverts (less than or 

equal to 30.5 m) because they disrupt a longer segment of the 

natural stream (U.S. Army Corps of Engineers, 2010). The 

assessment was based on characterization of stream channel 

geomorphology, habitat, and community structure of fish 

and benthic macroinvertebrates collected at 20 culvert sites 

in the Piedmont and Upper Coastal Plain of South Carolina 

(fig. 1, table 1). To assess potential culvert effects, data were 

collected in reaches above and below each culvert. The reach 

upstream from the culvert was considered free of culvert 

influence, whereas the downstream reach was potentially 

affected by the culvert. We examined differences in selected 

variables between upstream and downstream reaches to infer 

possible culvert effects. Because biological data are known 

to display a high degree of spatial and temporal variability 

(Schlosser, 1982; Downes and others, 1993), it was necessary 

to collect replicate samples. Given the study duration, it was 

not possible to collect data over multiple seasons or years at 

individual sites. Instead, spatial replicates were collected and 

used to evaluate culvert effects for each category of culvert 

length and physiographic province.

Description of Study Area

This study focused on the Piedmont and Upper Coastal 

Plain physiographic provinces (which correspond to the 

Piedmont and Southeastern Plains Level III ecoregions, 

respectively; U.S. Environmental Protection Agency, 

2013) of South Carolina (fig. 1). The Piedmont covers 

approximately 38 percent of the State, and the Upper Coastal 

Plain covers about 18 percent. These two provinces differ in 

their topographic, geologic, and biotic characteristics. The 

Piedmont is hilly and dominated by loamy to clayey Ultisol 

soils underlain by metamorphic and, to a lesser degree, 

igneous bedrock. In contrast, the Upper Coastal Plain has 

more subtle topography and sandy to clayey Entisol or Ultisol 

soils underlain by massive, semiconsolidated sand deposits of 

aeolian and marine origin (Swezey and others, 2016). Streams 

in the Piedmont generally have coarse-grained bed material 

and are commonly incised and disconnected from their 

floodplains. Streams in the Upper Coastal Plain are generally 

low gradient with relatively low banks and have less confined 

channels that often are well connected to wide floodplains. 

These streams are dominated by sandy bed material and 

greater amounts of organic debris. These differences in 

landscape and stream characteristics could moderate or 

exacerbate the potential effects of culverts on stream habitat 

and biotic communities.
! ! !

! !

!

! !

!

!

! ! ! !

!

!

!

!

!

!

!

! !

!

!

! !

!

! !

!

! ! !

! !

! !

!

!

! !

!

!

!

!

! !

!

!

! ! !

!

! !

!

! !

!

!

!

!

!

!

! ! !

!

! !

!

!

!

! !

!

!

!

!

! !

! !

! !

! ! ! !

!

!

!

! !

!

!

! ! ! ! !

! !

! !

!

! !

!

!

!

!

!

!

! ! !

!

!

!

! !

!

!

!

! ! !

!

!

! !

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

! !

!

! !

!

!

!

! !

!

!

! !

!

!

!

! !

!

!

!

! !

!

!

!

!

! ! !

!

!

!

!

! ! ! !

!!

!

! !

! !

!! !

!

!

!

!

!

!

!

!

!

!

! !

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! ! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

! ! !

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

! ! !

!

! !

!

!

! !

!

! !

!

!

!

!

!

! !

!

! !

! !

!

!

! !

!

!

!

!

! !

!

!

! !

!

! !

!!

! ! ! !

!

!

!

!

!

!

! !

!

! !

!

!

!

!

! !

!

! !

! !

! !

!

!

!

!

!

!

! ! !

!

!

!

!

!

! !

!

!

!

!

!

!

! !

!

!

!

!

!

!!

!

!!

!

!!!

!

!

!

!

!!

!

!

!

!

!

!!

!

!

!

!

!!!

!

!

!

!

!

!

!

!

!

!!

! !

!!!

!

!

!! !

!

!

!

!!

!

! !

!

!

!

!!!

!

!

!

!

!

!

!

!!

! !!

!

!

!!

!

!

!

!

! !!

!

!!!

!!!

!

!

!

!!!!

!

!

! !

!

!!

!

!

!!

!

!

!

!

!!! !

! !!

!!!

!

!

!

!

!

!

!

! ! !

!

!!!

!

!

!

!!

!

!!!

!! !

!

!

!!

!

!

!!

!

! !

!!

!!

!

!!

!

!!

!!

!

!

!

!

!

! !! !!

!!!

!

!!

!

!

!

!

!

!

!!

!

!

!

!

!!

!!!

!

!!

!!!!

!

!!!

!

!!

!!

!

!

!!

!

!

!

!!

! ! !

!

!

!

!!

!

!!! ! ! !!

!

!

!!

!

!

!

!

!!

!

!!

!

!

! ! !

!

!

!

!

!!!

!!

!!!! !

!

!

!

!!

!!

!!

!

! !

!!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!! ! !

!

!!

! !!

!!

!

!

!!

!

!!!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!!

!

!! !

!

!

!!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!!!!!

! ! ! !!

!

!

!! !

!!

!

!

!

!

!

!

!!!!!

!

!!

!

!

!

!

!

!!!

!

!

!

!!

!

!

!!

!! !

!

! !

!

!

!! !

!!!!

!

!

!!! !!!

!

!

!!!!

!

!

!

!!

!

!

!

! !

!

!!

! !! !

!

!

!

! !

!

!

!!!

!

!

!

!

!

!

!

!

!!!

!

!

!

!!

! ! ! ! ! !!

!

!!

!!

!

!

!

!!

!

!

!

!!

!!

! !!!

!!!!! !! ! !!!

!

!

! !!!!!

!

!!

!

!

!

!

!!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!!

! !!!!!!!!!

!

!

!

!

!

!!!!

!

!

!

!

!!

!

!

!!!!! !

!

!

!!

!

!

!!

!

!!!

!!!!! !

!

!

!!

! !!

! !

!!!

!!

!

!

!

!

!!

!

!

!!

!

!

!

!

!!

!

!

!

!

!!

!

!

!

!

!

!

!

! !

!!!! !!

!

!

!

!!!! ! ! !

!

!

!

!! !

!

!!

!

!

!

!!!

!

!!

!

!!

!

!

!!! !

!

! !

! !

!

! !!

!! ! !

!

!

!

!

!

!

!

!

!

!

! ! !

!

!!

!!

! !

!

!

! !!

!!!

!

!

!!

!

!

!

!

!

!!!

!

!

!

!!!

!

!!

!

! !

!

!

!

!

!

!

! ! ! !

!

!

!

!!

! !

!!!

!

!

!

!!

!

!

!

!

!

! ! !

!

!

!

!!!

!!!

!

!

!

!

! !

!!!!!!

!

!

!!!

!!

!

!!!! ! ! !

!

!

!!

!

!

!

!

!!

! !

!

!

!!!

!

!

!!

! !

!

!

!

!

!

!! !

! !

!

!

!

!

!

!!

!

!!

!!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!!

!

!

!!

!

!! ! !

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !!!!! ! !

!!

!

!

!!

!!!

! !

! !

!

!

!

!

!

!

!

!

!! !!

! !

!

!!!!!!

!

!

!

!

!

!

!

!

!

!

!

!!!!!!

!

!!!

!!! !!

!

! !

!

!

!

!!!

!

!

!

!!

! !!!

!

!!

!

!

!

! !!!

!

! !

!

! !!!! !

!

! ! !!

!

!!

!!!

!

!!

!!

!

! !!!! !

!

!!!! !

!!

!!!!

!

!

!

!

!!

!

!

!

!

!! !

!

!

!

!

!

!

!

! !

!!!

!

!

!!!!

!

! ! !

!

!! !

! !

!

!

!

!

!

!!

!!

!

!

!

!

!

!!

!

!

!

!

!

!

! !

!

!

!

!

!

!!! !

!

! !

!

! ! !!

! !!!

!! !

!

!

! !

!!

!

!!

!

!

!!!

!

!

!

!!

!

!

!

!!

!!!

!

!

! !

!

!

!

!

!

!

! !! !!!!

! !

!!!

! !

!

!

!

!

!!

!!!

!

!!

!

!

!

!

!!!!

!

!

!

!

!

!

!

!

!

!

!

!

! 

! !

!!

!

!

!

!!

! 

!

!

!

!

! !!

!

!

!

!

!

!

!

!

! !

! !

! !

!

!

!

!

!

!

! 

!!

!

!

!!

!

!

!

! ! !

!

!

!

!!

!!

!

! !

!

!

! !

!

!

!

!

!!!

!!

!

! !

!

!

!

!

!

! !

!

! !!

!!!

!!

!

!

!!!

!

!

!

!

!

!

!

!

!!

!!

!

!!

! !!!

!

!

!! !!!!

!

!!

!

! !

!

!!!

!!

!

!

!

!

!!!

! !!

!

!

!

!

!

!

!

!

!

!

!

!

!

! ! !

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!!!

!

!

!!!!!!

!!! !

!!!! !! ! !!!

!

!

!!

!

!!

! ! !!!

!!

!!

!

!! !!

!

!

!! ! ! !

!

!!

!!

!

!

!

!

!

!

!

!

!!

!

! !!

!!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!!!

! !! !! !!

! ! !

!

!

!

!!

!

!

!

!

!

!

!

!!

! !

!

!! !!

!

!!!

!

!

!!

!!!!

!

!

!!! !!! !!!!

!!

! !!

!! !!!!!!!

!

!

!

!! !! ! !

! !!

!

!

!

!

!

!!

!

! !

!

!

!

!

!

!

!

!!

!

!!!!!

!

!

!

!!

!!

!

!

! !

!

!

!!

!

!!

!

!!

!

!!

!

!

!

!

!

!

!!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!! !!

!

!!

!

!

!

!

!

!

! ! !

!

!

!

!

!

!

!

!

!!

!

!

!!!!!

!

!

!

!

!!

!

!

!!

!

!

!

!!

! ! ! !!

!

!

!

!!!!

!

!

!!!!!!

!! !

!

!!!

!

!

!!

!

! !

!!

!!

!

!

!!!!! !

! !

!!

!

!

!!

!

!

!

!

!

!

!

!!

!

!

!

!

!!!!

!

!

!

!

!

!

!

!!

!

!

!

!

!!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!!!

! !!

!

!

!

!!

!

!!!!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!!

!!

!

!!

!

!!

!

!! ! ! !

!

!

!

!

!

!!

!

!!

!

!!

!

!

!!!!!!

!

!

!

!

!

!

!

!

!

!

!

! !

!!!!!!

!

!

!

!

!!

!

!

!

!!

!

!!

!!!!

!

!

!

!

!!!!!

!

!

!

!!

!

!

!

!

!

!

!!!!!!!

!

!

!

!

! ! !

!!

!

!

!

!

!

!

!!

!!!!

!

!

!

!

!

!

!

!

!

! !!

! !!

!

!!!

! ! !

!

!!

!! !

!

!

! ! ! !

!!!

!

!!! !!

! !

!

!

!! !

!! !! !!

!

!

! !!

! ! !

!

!

!

!!

! !!!

!

!

!

!

!

!

!

!

!!

!

!

!! !! !!

!

!

!

!!

!

!!!

!!

! !!

! !

!

!

!

!

!

!

!

!

!

!

!!

! !

!

!

!!

!

! ! ! ! !

!

!

!

!!

!

!

!

!

!!

!

!

!!

!

!

!!!!!

!!!

!!

!

!

!

!!

!!

!!

!

!

!

!

!! !

!!

!!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!!

!

!

!!! !!!!!!

!!!!!!

!

!!

!

!

!

!

!!

!

!

!

!

!

!!

!

!!!

! ! !! !!

!

!

!

!!!

!

!!

!

!

!

!

!

!

!!

!

!

!

!!

!

!

!

!

!

!! !

!!!!!

! !

! !

!

!!

!!!!

!

!

!!!!

!

!! ! ! ! !

!!

!

!

!

!

!

!

!!!!

!!!

!

!

!

!

!!

!

!!!

!

!

!

! ! ! ! !

!

!

!

!

!

!

!

!

!!

!!!

!!!

!

!

! ! !

!

!

!

!

!!

!

! !

!!!

!

!

! !!

!!!

!!

!!!

!

!

!!!

!!!!!!!!!

!

!

!

!

!

!

! !

!

!

!

!

!!

!!

!!

!

!

!

!!

!

!

!

!!

!

!

!

! !

!

!

!

!

!

!

!

! !

!!!

!!

!!

!!

!

!

!!!! !

!

!!

!

!

! ! !!

!!!

!

!!

!

!

!

!

!

!

!!!!!

!

!!!

!

! !

!

!

!

!

!

!!!

!

!

!

!

!

!

!!

!

! ! !!

!

! !

!

!

!

!!!!

!

!

!!!

!

!!

!

!

!!

!!

!

!!

!

!

!

!

!

!

!

!

!!! !

!!!!!

!

!

!!

!

!

!

!!

!!!

!!!

!

!

!

!

!

!

!

!

!!!!!!

!!

!!

!

!! !

!! !

!

!

!

!

!!

! !!!!

!

!

!!

!!! !

!

!!!!!!

!

!!!

!

!

!

!

!

!

!

!

!

!

!!

!

! !

!

!

!

!

!

!!!!!

!!!!!!

!

!

!!!!

! ! !

! !

!!

!

!

!

!!

!!

!

!

!

!!!

!!!

!

!!

!

!

!!! !

! ! ! !! ! ! !

!!!!!

!

!! ! ! !!

!

!

!!

!

!

!!

!

!

!!

!

!

!

! !!!! !

!

!

!

!!!

!!!

!

!

!

!

!

!

!!

!!

!

!

!

!!

!

!!!!!

!

!!!!!!!! !!!!!!!!!!!!!!!

!

!

!

!

!

!!!!

!!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!!

!!

!

!

!

!!

!

!

!

!!

!!!!!!!!!

!!

!

!

!!

!

!

!

!

!!!

!!!!! !

!! !!

!

! !

!! !

!!

!!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!!!!!

!

!!!!

!!

!

!

! !

!!!!

!

!!!!

!

!!!

!!

!! !!!!!!!

!! !!!!

!!!

!!

!!

!

!!!

!

!

!

!

!

!!!

!!! !!!

!

!

!!

!

!!!

!

!

!

!!!!!

!!!!

!

!

!

!

!

!!

!

!!

!!

!!

!!!

!!

!

!

!

!!

!

!

!

!

!

!!

!!

!!

! !!

!

!! ! !! !!!!!! !

!!

!

!

!!!

!!

!

!!

!

!

!

!!

!!!

!!

!!

!!

!

!

!

! !

!

!

!

!!!!

!

!!

!

!

!

!

!!

!

!!!

!

!

!!

!!

!

!

!

!

!

!

!

!

!!

!!

!

!

!!!

!

!

!

!

!

!

!!

!

!!

!

!

!

!

!!

!

!

!!

!

!!!

!!!

!

!!

!!

!

!

!

!

!

!

!!

!

!

!!

!!

!!

! !!!!!!!!!!!

!!!!!

!

!

!!

!

!!!!!

!!!!!!!! !

!!

!

!

!!

!!

!

!

!

!

!!!!

!!!!!!!!!!! !!! !

!

!

!!

!

!

!

!

!

! !!!

!!

!!!

! ! !!!

!

!

!!

!!!!!

!

!

!! !

!!

!

!

!

!

!

!

!

!

!!

!

!

!!

!!!

!

!

!!

!

!!

!!

!!

!

!

!

!!!

!!!!

!!

!! ! !! !!

!

!

!!!!!

! !

!!

!!

!!

!

!!

!

!

!!

!

!!

!!

!

!

!

!!!

!

!

!

!

!

!!

!!

!

!!!!!!!

!

!!!

!

!

!

!

!!

!!!!!

!!! !

! !

!

!!

!

!!

!

!

!

!

!!!

!

!

!

!

! !

!!

!

!

!

!

!!

! !

!

!! !!!

!

!

!

!

! ! !

!

!

!

!

!

! !! !!!!

!

!

! !

!

! ! !! !!

!!

!

!

!

!!!

!

!

!

!

!

!!!

!

!!!

!

!

!

!

!

!!!

!

!!

!

!

!

!

!

!!!!

!

!

!

!

!!

!

!!!!!

!

!

!

!!

!

! ! !! !!

! !

! !

!

!

! !! !

!

!

!

!

!

!!! !

!

!

!!

!

!

!

!

!!

!

!

!!!

!!

!

!!!

!!! !

!

!!!

!

!

!!

!

!

!!

!!

!

!!! !

!

!!!!

!

!!

!! !!!!!

!

!

!

!

!!!

!

!!

!!!

!

!

!

!

!

!

!

!!!!

!!

!

!

!

!!!!!!

!

!

!

!

!

!

!

!

!

!!

!

!!!

!

! !! !

!

!

!

!!

!

!!

!

!!

!

!

!

!!

!

!

!

!

!!

!

!

! !

!!!

!

!

!!

!

!

!!

!

!

!

!

!!!

!

!

!!

!!!

!!

! !

!

!

!!

!!!

!

!

!

!

!!

!

!!!

!

!

!

!!

!

!!

!

!

!

! !

!!

!

!

!

!

!

!

!!

!

!

!

!

!!

!

!

!

!!!

!

!

!

!

!

! !!!

!

!!!!!!!

!

!!

!! !

!

!

!!!!

!!!

!

!

!! !!!!

! !

!!!

!

!!!! !!!

!

!!!

!!

!

!

!

!

!

!!

!!

!

!!

!!

!

!

!!!

!

!

! !

!!

!

!!

!!!!

!

!!

!

!!!

!

!

!

!

!

!

!

!

!

!

!!

!!

!

!

!

!

!!

!

!!

!

!

!

!

!

!!

!

!!!

!

!

!

!

!!!

!

!!

!

!

!!!

!!

!

!

!!

!!!

!!!

!

! !

!!!!

!

!

!

!

!

!

!

!

!

!

!!!

!!!

!

!

!

!

!

!

!

!

!!!

!

!!!! !

!

!

!

!

!

!

!!

!!!

!

!

!

!!

!

!

!

!

!

!!

!

!!

!

!

!

!

!!!

!

!!!

!!

!!! !

!

! ! !

!! !

!

!

!

!

! !

!

!

!! !!

!

!

!

!!!!!

!

!!

!

!

!

!

! !

! ! ! !

!

!

!!! !

! ! !

!

!

!

!

!

!

!

!!!

!

!!

! !

!

!!

!!!

!

!!!

!!!

!!

!

!!

!

!

!

!

!

!!

!!

!!

!

!

!

!

!!

!

!

!!

!

!

!

!

!!

!!

!

!

!

!!!

!

! !!!!

!!!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!!

!

!!

! ! !

!

!

!!

!!

!!! !

!!!

!

!!! !! !

!

!

! !

!

!

!

!

!

! !! !!!!!

!

!

!

!

!

!

!

!!!

!!

!! !!! !!

!!!!!!

!

!!!

!!

!

!

!

!

!!!!!

!

!

!

!!

!

!!

!

!

!!

!!

!!

!

!

!

!

!

!

!

!

!

!!

!

!!

!

!

!

!

!

!

! !!!!!!!!!!!!

!

!

!

! !

!

!!!

! !

!!

!

!

!

!

!

!!!

!

! !!!

!!

!

!

!

!

!

!!!!

!

!

!!!! !!!

!

!

!

!

!

!

!

! !

!

!

!

! !! !!!!! !! !!

!

!!

!

! !

!

! !

!! ! !

! ! !!! !!! !!

!! !

! !! !! 

!

!

!

!

!

!

!

!

!!

!

!

!

! !

!!!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!!

!!

!

! !

!

!

!

!

!

!

!

! !

!

!

!

!!!

!

!

!

!

!

!

!

!

!

!

!

! !!!! !

!

!!

!

!

!

!

!!

!

!

!!

!

!

!

!

!

!

!

!!

!

!

!

!!!

!

!!

!

!

!

!

!

!!!!!!!

!

!

!!

!

!

!

!

!!!

!

!!

!

!

!

!!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!!

!

!

!! !

!

!

!!!

!!!!! !

!!! !

!

!

!!!

!!

!!

!

!

!

!

!!

!!!

!!!!

!

!!

!!

!

!

! !

!

!!

!

!

!

!!!

!!!!

! !

!!!!!!!

!

!

!

!

!!

!

!

!!!!!!!

!!

!

!

!

!

!

!

!

!

!

!

!!! !

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

! !!

!!

!!

!!

!!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!!!! !

! !

!!

!

!

!

!

!!

!

!

!

!

!

!!

!

!!!

!

!

!!!

!!

!!

!

!

!

!

!!!

!

!

!!!!!!!!!

! !

! !

!

!

!

!!

!

! ! !

!

! !

!

!!!!!!!!!!

!

!

!

!

!!

!

!

!!

!!!!!!!

!

! !

! ! !

!!!!!!! !!!

!!!!

!!

!

!

!!

!

! !!!

!

!

!!!!!!!!

!

!

!!!!!

!

!

!

!!

!

!

!

!

!

!!

!!!!!

!!!

!

!!!

!! !!!

!

!!!!!!

!

!

!

!

!

!

!

!

!

!

!

!!

!!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!!

!

!

!!

!

!

!

!

!

!

!

!!

!

!

!

!!

!

! !

!!

!!

!

!

!!

!

!!

!

!

!

!

!!

!

!

!

!

!

!

! !

!!

!

!

!!!

!

!!

! !

!! !

!

!

!

!

!

!

!

!

!

!

!

!

!

! !!

!

!

!

!

! !!!! ! !!!! ! !!!!

! !!!!! ! !!! 

! !!

!

!

! !

!!!!!! 

!

!!

!!!

! ! ! !!! !!!

!

! ! !!!!

! !

! !! ! !!!!! !

!!!

!

!

!

!!

!

!

!

! ! ! !!! !!

! ! !

!!

!

!

!!

!

!

!

!

!

! !

!!!

!!

!

!

!

!

!

!

! !!!

!

! ! !

!

!

!!

!

!

!!!

!!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

! !!! !

!

!

!

!!!

!

!

!

!

!

!

! !! !

!

!

!

!!

!

! ! !

!

!

!

!

!

!!!!!

!!

!

!!

!

!!!

!

!

!

!

!

!!!!! !!

!

!

!

!

!!

!

!!

! !

!

!!!

!

!

!

!

!! !

!

!

!

!

!!

!

!!

!

!

!

!

!

!

!!

!

!

!

!

!!

!!

! !!

!!!!

!

!

!

!

!!

! !!

!

!

!

!!

!

!

!

!

!

!

!

!

!

! !!! !

!

!

*

82° 81° 80° 

34°33°

Physiographic province

PiedmontUpper Coastal PlainMiddle Coastal PlainLower Coastal Plain

SCDOT culvertStudy culverts

Long (greater than 30.5 meters)Short (less than or equal to 30.5 meters)

#

#

#

#

#

#

#

#

EXPLANATION

cowbr

bluebr

enoree

drycrk

sadler

timscrk

taylorcr

t2rockcr

centercr

indiancr

trueblue

millersfk

beaverdam

trib4hole

t2taylorcr

trib2payne

lilhogskin

bigpinetree

trib2allison

tinker

NORTH CAROLINA

GEORGIA

SOUTH CAROLINA

0 

0 

35°

Base modified from U.S. Geological Survey digital data, 1:2,000,000 scale, 1972

Figure 1. Map showing locations of selected South Carolina Department of Transportation (SCDOT) culverts and physSouth Carolina.
4 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Table 1. Selected culvert sites in South Carolina that were assessed for morphological and ecological effects, 2016–18.

[Culvert length classes: short, less than or equal to 30.5 meters; long, greater than 30.5 meters. USGS, U.S. Geological Survey; km2, square kilometer; US, 

United States; SC, South Carolina; I, Interstate]

USGS station number USGS station name Site 

identification

Physiographic 

province

Culvert 

length class

Drainage area 

(km2)

340427082131900 Beaverdam Branch on US 221, near 

Bradley, SC

beaverdam Piedmont Short 13.36

345132081212000 Blue Branch on SC 322, near York, 

SC

bluebr Piedmont Short 5.46

335324081452100 Dry Creek on SC 193, near Saluda, 

SC

drycrk Piedmont Short 12.28

340537081394100 Indian Creek on SC 194, near Saluda, 

SC

indiancr Piedmont Short 18.23

342050082243600 Little Hogskin Creek on SC 20, near 

Due West, SC

lilhogskin Piedmont Short 4.20

350632081155500 Tributary to Allison Creek on SC 236, 

near Clover, SC

trib2allison Piedmont Short 2.85

344024082135600 Tributary to Payne Branch on SC 418, 

near Fountain Inn, SC

trib2payne Piedmont Short 2.38

341438080596000 Center Creek on I-77, near Ridgeway, 

SC

centercr Piedmont Long 11.60

343654081541500 Enoree Creek on SC 49, near Cross 

Anchor, SC

enoree Piedmont Long 4.56

342916081513800 Millers Fork Creek on SC 72, near 

Clinton, SC

millersfk Piedmont Long 2.15

345347080592900 Taylor Creek on I-77, near Rock Hill, 

SC

taylorcr Piedmont Long 8.00

345009081581300 Tims Creek on I-26, near Moore, SC timscrk Piedmont Long 4.77

343953081014400 Tributary to Rock Creek on I-77 near 

Richberg, SC

t2rockcr Piedmont Long 2.12

345207081001200 Tributary to Taylor Creek on I-77, 

near Rock Hill, SC

t2taylorcr Piedmont Long 3.39

342115080285500 Big Pine Tree Creek on US 1, near 

Cassatt, SC

bigpinetree Upper Coastal Plain Short 14.17

342652080313400 Cow Branch on Lockhart Road, near 

Westville, SC

cowbr Upper Coastal Plain Short 10.83

333722080495800 Sadler Swamp on SC 122, near St. 

Matthews, SC

sadler Upper Coastal Plain Short 8.75

332418081304100 Tinker Creek on SC 781, near White 

Pond, SC

tinker Upper Coastal Plain Short 11.06

333521080440800 Tributary to Four-Hole Swamp on US 

176, near Cameron, SC

trib4hole Upper Coastal Plain Short 3.83

334250080423900 True Blue Creek on True Blue Road, 

near Singleton, SC

trueblue Upper Coastal Plain Short 6.27
Approach and Methods 5

Previous Investigations

It is difficult to extrapolate findings from other studies 

of culvert effects on stream ecosystems to the present study 

because of past land-use disturbances. Researchers in other 

States (for example, Ohio [Tumeo and Pavlick, 2011], Texas 

[Cleveland and others, 2013], and Minnesota [Zytkovicz and 

Murtada, 2017]) have investigated different approaches to 

culvert design and the possible implications to stream systems, 

but the physical landscape settings are different from the 

present study area. Historical agricultural practices over much 

of the southern Piedmont led to greatly altered stream systems, 

many of which have deeply incised channels that are filled in 

with fine sediment (Trimble 1974; Jackson and others, 2005; 

Voli and others, 2013). Such incised channels have greater 

volumetric capacity and experience fewer overbank flows 

than unaltered streams; therefore, high-flow conditions disturb 

stream channels more frequently because the hydraulic energy 

is constrained within the channel. These factors make the 

current study an important contribution to better understand 

how, if at all, box culverts may affect channel stability, habitat, 

and biotic communities in these previously altered systems.

The influence of culverts on benthic macroinvertebrates 

and nongame fish species has received relatively little 

scientific study. A consistent finding from two studies was that 

disturbance to the macroinvertebrate community tended to 

be localized and was likely driven by altered habitat adjacent 

to the culvert (Khan and Colbo, 2008; Peterson, 2010). It is 

important to note that these two studies focused on streams 

that have coarse-grained bed sediments and disturbance led 

to relatively small changes in bed-material size. In streams 

of the southeastern United States, disturbance often results 

in copious amounts of sand and silt becoming the dominant 

bed material; this substrate is not suitable for many sensitive 

taxa. We are unaware of any studies on southeastern Piedmont 

streams that have investigated how macroinvertebrate 

communities may differ in relation to culvert proximity. 

The negative effects of fine sediment on macroinvertebrate 

communities, however, have been documented in many 

studies (Waters, 1995; Wood and Armitage, 1997; Kaller 

and Hartman, 2004; Jones and others, 2012; Gieswein and 

others, 2019).

In contrast to benthic macroinvertebrates, fish generally 

are more mobile and better able to avoid disturbances 

associated with localized habitat alterations from 

culvert-induced scour. A concern with fish is their ability to 

move through culverts to allow for colonization, dispersal, 

and gene flow (Anderson and others, 2012). Research in this 

regard has focused mainly on the swimming abilities of adult 

salmonids and, in limited cases, native or protected species 

(Benton and others, 2008; Norman and others, 2009; Bouska 

and Paukert, 2010). In Great Plains streams, physical factors 

that influenced the passage of small fish through culverts were 

water velocity; suitable depth; culvert slope, length, width; and 

perch height that limited migration of target species (Bouska 

and Paukert, 2010). Perch height, or “perching” refers to a 

situation where the bottom of the culvert is above (at a higher 

elevation) the bed of the stream. This can lead to a sharp step 

in the longitudinal profile that may be a barrier for fish and 

other aquatic species. Most studies of culvert effects on fish 

have focused on the requirements of specific groups or species 

and have rarely considered entire community assemblages. 

However, ensuring no net loss of ecosystem function (U.S. 

Army Corps of Engineers, 2010) resulting from in-stream 

engineering activities requires an understanding of potential 

effects to the biotic community composition to effectively 

characterize and mitigate impairments.

Approach and Methods

We compared geomorphology, habitat characteristics, 

and community assemblages from the upstream reach to those 

from the downstream reach at each site to infer possible effects 

of culverts. This approach assumed that upstream reaches were 

relatively free from the influence of culverts and were suitable 

as controls to compare to downstream reaches; however, some 

culverts may also alter upstream habitat conditions.

An ideal approach for assessing the effects of a given 

activity is to collect pre- and post-disturbance data from 

disturbed and control sites that can then be evaluated in a 

before-after-control-impact analysis framework (Smokorowski 

and Randall, 2017). This approach often is not attainable 

because ecological impairment frequently is studied long after 

a structure or process was put in place, which is the case for 

the current study. Therefore, we collected spatial replicates 

of “control-impact,” where the difference in geomorphic and 

biotic conditions between upstream and downstream reaches 

could be evaluated to infer the possible effects of culvert 

presence and whether there is variation by culvert category 

(physiographic province or culvert length). Thus, we examined 

metrics intended to detect differences between upstream and 

downstream geomorphic and biotic community characteristics.

Site Selection

Culvert locations were provided by the SCDOT, and 

additional locations were identified by intersecting the 

USGS high-resolution National Hydrography Dataset 

(U.S. Geological Survey, 2016) with a South Carolina 

roads digital data layer (http://info2.scdot.org/sites/GIS/

SitePages/default.aspx; accessed July 7, 2017) by using 

ArcGIS 10.3 software. The drainage area above each culvert 

was determined by using the USGS National Elevation 

Dataset (U.S. Geological Survey, 2017) 1-arc-second 

digital elevation data and ArcGIS 10.3 software. Sites were 

considered for further evaluation if the drainage area was less 

than 25.9 square kilometers and landcover was minimally 

disturbed (50–100 percent forest, 0–25 percent agriculture, 

and 0–10 percent urban), based on the 2011 National Land 

Cover Dataset (U.S. Geological Survey, 2014). The initial 
6 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

intent of the study was to select five long and five short 

culverts from both the Upper Coastal Plain and Piedmont 

physiographic provinces (n=20) to achieve a balanced design 

for data collection. This design would allow for an assessment 

of differences in ecological and geomorphic conditions on 

the basis of culvert length and physiographic province. The 

initial criteria, however, limited the number of potential sites 

to 20 (out of more than 9,000). During field reconnaissance, 

we found that several of these sites were immediately 

downstream from impoundments or were located on swamps. 

Furthermore, of these 20 culverts, only 3 were longer than 

30.5 m. After removing all constraints except culvert type 

(box culvert), five long culverts suitable for study still could 

not be found in the Upper Coastal Plain. Therefore, the design 

was altered to focus on short culverts in the Upper Coastal 

Plain and Piedmont, allowing for a regional comparison of 

short culverts, and to focus on long culverts in the Piedmont 

to evaluate the role of culvert length on biotic communities 

and stream geomorphology in the Piedmont physiographic 

province only.

After an initial geographic information system 

(GIS)-based screening, field reconnaissance was completed 

to evaluate local-scale conditions. The primary focus was to 

identify site-specific conditions that may limit or confound the 

ability to isolate culvert effects. For example, some streams 

in the Upper Coastal Plain are characterized as swamp-like 

and have multiple channels. When a berm is built across the 

floodplain for a road bed and a culvert is installed, the once 

multichannel stream is constrained into a single-channel 

passage under the road that continues on the downstream 

side. Although constraining the stream in this manner is 

related to the culvert, it is not caused by the interaction of 

stream flow and culvert design but rather by confining the 

once broad floodplain. An alternative explanation could be 

that the transition from multiple channels to a single channel 

represents a natural change in channel form due to local valley 

constrictions or other natural factors, and engineers exploit 

this location to reduce design and construction costs associated 

with crossing multiple channels. Regardless of cause, this 

difference in channel form makes it difficult to effectively 

compare conditions upstream, where there are multiple 

channels and substantial areas for overbank flow and energy 

dissipation, to conditions downstream from the culvert, where 

there is often a single channel. Therefore, only sites that had 

a single confined channel above and below the culvert were 

included in the study.

Reach Layout

Field assessments were completed at two scales, by 

reach and by zone. Fish community, habitat, and geomorphic 

characterizations were assessed at the reach scale: one 

reach above and one reach below the culvert. Reaches were 

100 m long, except at the site centercr, where reach length 

was 120 m. Habitat and geomorphic characteristics were 

assessed along transects crossing the channels. Transects 

were numbered from downstream (transect 1) to upstream 

(transect 22). In general, data were evaluated by comparing 

upstream (assumed to be free of culvert influence) to 

downstream (potentially affected by culvert) to assess 

whether box culverts may lead to changes in stream channel 

morphology, aquatic habitat, or community structure.

Benthic macroinvertebrates and particle-size distributions 

were sampled in four discrete zones that varied by proximity 

to the culvert (fig. 2). Zones were 20 m long and were situated 

adjacent to both ends of the culvert and at both ends of the 

reach. Zone 1 was at the top of the reach (transects 20–22) 

and was designated the “background zone.” This zone was 

assumed to be free of culvert influence. Zone 2 was adjacent 

to the upstream side of the culvert (transects 12–14) and 

was called the “upstream impact zone.” This zone was used 

to evaluate any localized effects upstream from the culvert. 

Next was zone 3, the “downstream impact zone,” which was 

adjacent to the downstream side of the culvert (transects 9–11) 

and used to evaluate any localized effects downstream from 

the culvert. Zone 4 was the “recovery zone,” which was at the 

most downstream end of the reach (transects 1–3) and was 

used to evaluate whether any culvert effects were localized 

or persistent. Macroinvertebrate and particle-size data were 

compared among the zones, with primary interest in how the 

zones adjacent to the culvert compared to those farther away. 

Possible differences were examined by culvert length class and 

physiographic province.

Habitat and Geomorphic Assessments

Habitat and geomorphic features were assessed to 

characterize aquatic habitat, including morphology of the 

stream channel, channel-bed sediment-size distributions, 

canopy closure, in-stream habitat features, large woody debris 

(LWD), macrobedforms (geomorphic channel units [GCUs]), 

and streambed slope (table 2). The general reach layout and 

assessment procedures are described in Fitzpatrick and others 

(1998) and McDonald and others (2018). Modifications of the 

referenced methods primarily relate to reach layout and are 

indicated in table 2.

In addition to characterizing habitat and stream channel 

morphology, detailed culvert measurements were made 

to evaluate the size of the culvert in relation to the stream 

channel, which could affect local hydraulics and aquatic 

habitat. Culvert slopes were also measured and compared to 

streambed slopes to evaluate possible deviations that could 

alter local velocity, associated stream power, and scour (Abt 

and others, 1985).
Approach and Methods 7

100 meters 100 meters

Upstream reach

Flow

Downstream reach

Background (1)

Upstream

impact (2)

Downstream

impact (3)

Recovery (4)

20 meters 20 meters 20 meters

20 meters

Culvert

Figure 2. Diagram of reaches, transects, and zones sampled in streams at selected culvert sites in 

South Carolina, 2016–18. Dashed lines represent transects where habitat and geomorphic characteristics 

were assessed. Transects were numbered from downstream (transect 1) to upstream (transect 22). 

Macroinvertebrates were collected and bed sediment was characterized in four 20-meter zones. Zone 1 is 

the background zone, assumed to be relatively free from culvert effects. Zone 2 is the upstream impact zone, 

immediately upstream from the culvert. Zone 3 is the downstream impact zone, immediately downstream from 

the culvert. Zone 4 is the recovery zone, at the downstream end of the reach.

Table 2. Habitat and geomorphic features measured in streams at selected culvert sites in South Carolina, 2016–18; associated 

method references; and any deviations from the cited methods.

[NA, not applicable; GCU, geomorphic channel unit]

Habitat/geomorphic 

variable Method reference Description or modification to referenced methods

Bankfull depth Fitzpatrick and others (1998) NA

Bankfull width Fitzpatrick and others (1998) NA

Bankfull cross-sectional 

area

NA Product of mean bankfull depth and bankfull width

Canopy closure Fitzpatrick and others (1998) Only facing upstream and downstream at each transect

Channel-full depth McDonald and others (2018) NA

Channel-full width McDonald and others (2018) NA

Channel-full crosssectional areaNA Product of mean channel-full depth and channel-full 

width

Flow velocity Fitzpatrick and others (1998) Thalweg velocity only

GCU count and length Fitzpatrick and others (1998) NA

Large woody debris 

volume

McDonald and others (2018) Product of total length and mean diameter

Bed-sediment particle size Wolman (1954); Fitzpatrick and others (1998); 

McDonald and others (2018)

Particles measured from the active channel only

Thalweg slope Fitzpatrick and others (1998) NA

Wetted depth Fitzpatrick and others (1998) NA

Wetted width Fitzpatrick and others (1998) NA

Wetted cross-sectional area NA Product of mean wetted depth and wetted width
8 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Channel morphology was assessed at three elevations: 

wetted, bankfull, and channel-full (incised channel top) levels 

(fig. 3). Wetted channel dimensions were based on water 

levels measured during site visits when habitat variables were 

measured. Bankfull dimensions were based on morphological 

indicators, where present, and extrapolated where indicators 

were inadequately defined (Wolman and Leopold, 1957; 

Harman, 2000). Bankfull dimensions had the greatest 

uncertainty because indicators were deficient or nonexistent 

at some sites, especially in many incised channels. Lastly, 

channel-full dimensions were measured at the top of the first 

surface above the bankfull elevation (terrace), where water 

would begin to spill out of a defined channel. In channels that 

were not incised and had an intact floodplain, bankfull and 

channel-full elevation were the same.

Bed sediments were sampled by using the pebble count 

approach originally described by Wolman (1954), with 

deviations presented in table 2. Particle-size data were used 

to evaluate the distribution of grain sizes in the zones where 

macroinvertebrates were collected, and data were summarized 

to the reach and zone level. Selected particle-size percentiles 

were calculated for comparison between reaches and across 

strata (Kondolf and Wolman, 1993). The median diameter 

(D50) describes the central tendency; the 16th-percentile 

diameter (D16) describes the fine tail (lower portion) of the 

distribution, and the 84th-percentile diameter (D84) describes 

the coarse tail (upper portion) of the distribution. The subscript 

represents the percentage of particles with diameter finer than 

the given value. For example, if D16 is equal to12 millimeters 

(mm), then 16 percent of the sampled particles had diameter 

less than or equal to 12 mm. Percentiles were calculated after 

removing observations of bedrock, which does not have a 

defined diameter. Instead, the number of bedrock encounters 

was recorded for each zone.

Large woody debris (Gregory and others, 2003; Wohl, 

2017) was measured and classified following the techniques 

described in McDonald and others (2018). This method uses 

a census approach where all LWD greater than 1 m in length 

and greater than or equal to 0.10 m in diameter was included 

in the assessment. These data were converted to volume, 

assuming each piece of wood could be approximated as a 

cylinder. The values were then aggregated to the reach and 

zone levels to allow for comparison among reaches, within 

and between sites.

Fish Community Assessments

Fish communities were assessed in two 100-m reaches 

at each site, one reach downstream from the culvert and one 

reach upstream from the culvert (fig. 2). Sampling methods 

generally followed South Carolina Department of Natural 

Resources standard operating procedures (Scott and others, 

2009). Block nets were placed at the upper limits of each 

reach. A Smith-Root LR–20B battery-powered backpack 

electrofishing unit was used to make a single upstream pass 

through each sampling reach. Collected fish were identified 

to species, and total length (in millimeters) was measured for 

up to 30 individuals of each species. Vouchered specimens 

were fixed in 10 percent formalin, transferred to ethanol for 

preservation, and cataloged in the Florida Museum of Natural 

History fish collection. Fish data were stored in the USGS 

BioData Retrieval System and are publicly accessible (U.S. 

Geological Survey, 2019).

Wetted width

Active channel width

Bankfull width

Channel-full width

Figure 3. Annotated photograph showing the 

channel levels, or elevations, where channel 

morphology measurements were made. Figure 

modified from McDonald and others (2018). 
Approach and Methods 9

Macroinvertebrate Community Assessments

Benthic macroinvertebrate samples were collected 

in the four 20-m sampling zones at each site (fig. 2). The 

composited sample compromised 10 subsamples collected 

from all available habitats within a zone. Each habitat type 

was sampled in proportion to its occurrence for a timed 

duration of 30 seconds per subsample. This collection 

procedure approximates the Timed-Qualitative Multiple 

Habitat Sampling Protocol of the South Carolina Department 

of Health and Environmental Control (South Carolina 

Department of Health and Environmental Control, 2017). 

A D-frame dip net (500-micrometer [μm] mesh) was used 

to sample undercut banks, leaf packs, and streambeds. For 

woody snags and large cobbles (128–256 mm), the material 

was lightly brushed and visually inspected. The samples 

were sieved through a 500-μm sieve, and large organic and 

inorganic material was visually inspected and removed. The 

remaining material was transferred to a 1-liter bottle and 

preserved with 10 percent buffered formalin. Samples were 

shipped to Pennington & Associates, Inc., in Cookeville, 

Tennessee, where macroinvertebrates were identified to 

the lowest practicable taxonomic level (Pennington, 2016). 

Macroinvertebrate data were stored in the USGS BioData 

Retrieval System and are publicly accessible (U.S. Geological 

Survey, 2019).

Data Analysis

Initially, all habitat and biological data were screened 

by using summary statistics, simple correlations, bivariate 

plots, and boxplots to compare data within sites and within 

and among culvert categories. This preliminary data analysis 

allowed for the examination of distributions, detection of 

outliers, and identification of possible associations between 

variables. Further statistical tests used two approaches: 

(1) comparisons of reach-level and culvert-category-level 

summaries (averages) with the use of nonparametric statistical 

tests and (2) comparisons of community compositions with 

the use of multivariate permutation tests. Pairwise comparison 

tests were used for all habitat and geomorphic data and the 

fish community metrics (for example, the Shannon-Wiener 

diversity index). For pairwise comparisons, the reach or zone 

averages of variables of interest were used to test for statistical 

significance. Because of the small sample size and large 

variability of measured habitat features, statistical tests used 

a significance level (α) of 0.10. This significance threshold 

was used because the chance of Type II error can increase 

substantially when sample size is small (Kish, 1959; Kim, 

2015). Furthermore, given the low within-group sample sizes, 

nonparametric tests were used to avoid the assumptions of 

normality that are difficult to verify with small samples. To 

examine differences within sites (that is, differences between 

upstream and downstream reaches) a paired-sample Wilcoxon 

signed-rank test was used to test the null hypothesis that 

the distribution of paired differences is symmetrical around 

zero (Ott and Longnecker, 2001). When comparing between 

the different categories (for example, short Upper Coastal 

Plain culverts versus short Piedmont culverts), a Wilcoxon 

rank-sum test was used to test for a shift in distribution of 

ranks between two samples. Before running statistical tests, 

the morphological data were converted to z-scores (Ott and 

Longnecker, 2001) to determine how individual transect 

measurements deviated from the site-level average. This 

rescaling approach reduces the effect of absolute magnitude 

on statistical analysis because all observations represent the 

number of standard deviations from the respective site-level 

average. All pairwise statistical analyses were conducted 

using the software R (R Core Team, 2017), and the Wilcoxon 

signed-rank tests used implementations in the coin package 

(Hothorn and others, 2008). To test for longitudinal differences 

in channel constriction or widening (ratio of channel width 

to culvert width) that may be related to culvert proximity, a 

Kruskal-Wallis test was used. This analysis tested the null 

hypothesis that data from each transect are from the same 

distribution.

For fish community data, the catch per unit effort (C/f) 

was calculated for sample comparison (Hubert and Fabrizio, 

2007). For macroinvertebrate community data, species that 

occurred in less than 2 percent of the samples were eliminated. 

Ambiguities in the taxonomic assemblage were resolved by 

distributing the abundance of ambiguous individuals among 

those identified to lower taxonomic levels according to the 

relative abundance of those identified to the lowest level by 

using the Invertebrate Data Analysis System (Cuffney and 

Brightbill, 2011). This approach maximizes taxa abundance 

without affecting the taxa richness and is one of the methods 

suggested by Cuffney and others (2007).

For both fish and macroinvertebrates, the assemblage 

data were square-root transformed and a Bray-Curtis 

similarity matrix was calculated by using Plymouth Routines 

in Multivariate Ecological Research (PRIMER) software 

(PRIMER v7; Clarke and Gorley, 2015). A square-root 

transformation is a mild adjustment of quantitative data to 

reduce the influence or dominance of very abundant species. 

Several routines in the PRIMER software were used to 

evaluate the biological community data. A one-way analysis of 

similarities (ANOSIM) test was performed to assess statistical 

differences between zones within each category. Nonmetric 

multidimensional scaling (nMDS) plots produced an 

ordination based on resemblance matrices in two-dimensional 

(2D) and three-dimensional (3D) space; samples that plot 

near each other are more similar than samples that plot far 

away. In conjunction with nMDS, hierarchical cluster analysis 

(CLUSTER) with similarity profile analysis (SIMPROF; 

with 999 permutations) tests identified statistically significant 

groupings of samples with similar biological community 

composition. Whereas nMDS plots provide a qualitative 

view of how samples plot relative to each other, CLUSTER 

with SIMPROF provides statistically significant groupings 

of samples.
10 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Associations between biological community structure 

and abiotic and biotic variables were explored by using 

the Bio-Env + Stepwise (BEST) routine in PRIMER. The 

BEST routine determines which variable or combination of 

variables explains the variation in the biological community. 

Draftsman plots were examined to eliminate correlated 

abiotic (habitat) variables. Then, the agreement between the 

biological community was compared with the variable matrix 

(Euclidean matrix for habitat variables or Bray-Curtis matrix 

for macroinvertebrate metrics) by using a Spearman rank 

correlation coefficient.

The Shannon-Wiener diversity index, Simpson’s 

diversity index, and Pielou’s evenness are metrics commonly 

calculated for biological communities. These diversity indices 

provide more information about community composition than 

taxonomic richness alone. The Shannon-Wiener index is the 

ratio of the number of species to their importance values in 

the community. Simpson’s diversity index is a measure of 

both taxonomic richness and the relative abundance of each 

species and is therefore an indicator of dominance. Pielou’s 

evenness is a measure of how evenly species are distributed in 

the community.

Habitat and Geomorphic 

Characterization

Overall, geomorphic and habitat characteristics were 

highly variable regardless of culvert length or physiographic 

province, possibly due to the influence of site-specific 

factors masking or overriding potential culvert effects. The 

following sections focus on a subset of the geomorphic and 

habitat characteristics to evaluate changes to broad-scale 

habitat, channel morphology, LWD, and bed-sediment 

texture. Where differences were observed, statistical tests 

were performed to evaluate the strength of the relation. The 

habitat and geomorphic data used in this report are available at 

https://doi.org/10.5066/P9VD9AYY (Riley and Walsh, 2019).

Geomorphic Channel Units

Across all sites, runs were the most prevalent GCU, 

accounting for an average of 75 percent of the reach length, 

followed by riffles (15 percent), and pools (10 percent). A 

greater prevalence of riffles was observed in the Piedmont 

(mean = 20 percent of reach length) than in the Upper Coastal 

Plain (mean = 2 percent of reach length). Upper Coastal 

Plain riffles were formed by woody debris, and their temporal 

persistence likely is shorter than that of the rock-dominated 

riffles in the Piedmont. Although there were differences in 

the proportions of GCUs between physiographic provinces, 

as expected, no substantial or significant differences were 

observed between the long or short culverts within the 

Piedmont.

The number of GCUs encountered within a reach 

served as an indicator of habitat complexity. In five of the 

six Upper Coastal Plain sites, habitat complexity was greater 

downstream from the culvert, as indicated by a greater number 

of GCUs in downstream reaches (fig. 4). A paired-sample 

Wilcoxon signed-rank test indicated a significant difference 

in channel complexity between upstream and downstream 

reaches in the Upper Coastal Plain (table 3); however, this 

pattern was not observed for Piedmont sites of either culvert 

length class. Comparing the difference in the number of GCUs 

from upstream to downstream reaches between regions, for 

short culverts only, indicated that Upper Coastal Plain sites 

generally had a greater difference in habitat complexity 

between upstream and downstream (fig. 4). On average, 

the Upper Coastal Plain sites had four more GCUs in the 

downstream reach than in the upstream reach, whereas the 

Piedmont sites (short culverts) had, on average, one fewer 

GCU in the downstream reach. The results from a Wilcoxon 

rank-sum test indicated a significant difference in distributions 

between regions. The estimated median difference (or shift 

parameter) of 3.00 does not necessarily have an ecologically 

meaningful interpretation. Rather, the positive estimate simply 

indicates that Piedmont sites collectively did not show the 

degree of channel complexity increase from upstream to 

downstream that was observed at the Upper Coastal Plain 

sites. A comparison between short and long culverts in 

the Piedmont indicated no significant differences between 

upstream and downstream channel complexity.
Habitat and Geomorphic Characterization 11

Piedmont long Piedmont short Upper Coastal Plain short

5

0

10

15

Number of GCUs

centercr

enoree

millersfk

t2rockcr

t2taylorcr

taylorcr

timscrk

bluebr

drycrk

indiancr

lilhogskin

beaverdam

trib2allison

trib2payne

cowbr

sadler

tinker

trib4hole

trueblue

bigpinetree

Site identification

Downstream reach

Upstream reach

EXPLANATION

Figure 4. Graph showing habitat complexity, as defined by the number of geomorphic channel units (GCUs) per reach, at 

selected culvert sites in South Carolina. Each panel represents a combination of physiographic province and culvert length 

class: Piedmont long culverts, Piedmont short culverts, and Upper Coastal Plain short culverts.
12 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Channel Morphology

Channel morphology was assessed at three elevations: 

wetted, bankfull, and channel-full levels (fig. 3). The 

assessment of culvert effects, however, focused only on 

channel-full characteristics because the variability in water 

level between sites affected wetted dimensions and because 

of the uncertainty associated with delineation of bankfull 

dimensions in many of the incised streams. To evaluate 

differences in gross channel morphology (width, depth, 

cross-sectional area), data were normalized as previously 

described. Transect data were then summarized to the reach 

scale to evaluate differences in average channel characteristics 

between upstream and downstream reaches. Cross-sectional 

area was the primary metric for evaluating changes in 

channel morphology. This variable represents gross changes 

in morphology without considering the dimension (lateral 

or vertical) of adjustments, which may change over time in 

response to a reoccurring perturbation (in the sense of channel 

evolution models; Simon, 1989). In general, channel-full area 

was variable at the Piedmont sites, and there was no consistent 

trend between upstream and downstream reaches for long or 

short culverts (fig. 5). At five of the six Upper Coastal Plain 

sites, mean channel-full area increased downstream from 

the culvert (mean difference of 2.16 square meters [m2]), 

which differed significantly from the short culvert sites in 

the Piedmont (mean difference of 0.10 m2) (table 4). The 

Wilcoxon rank-sum test indicated that the distribution in the 

Upper Coastal Plain was shifted 0.98 unit (approximately 

one standard deviation) compared to Piedmont sites. Like 

the analysis of GCUs, the positive value (shifted to the right 

of zero) indicates that the difference between upstream and 

downstream channel-full area is greater at Upper Coastal Plain 

sites than at Piedmont sites.

Field observations, particularly at the Upper Coastal 

Plain sites, as well as exploratory plots, indicated that 

channel-full depths were often greater downstream from 

the culverts (fig. 6). The results of a Wilcoxon signed-rank 

test showed a significant difference in the average depth 

between upstream and downstream reaches in the Upper 

Coastal Plain (table 5); however, no significant differences 

between upstream and downstream reaches were observed 

for Piedmont sites of either culvert length class (table 5). The 

difference in average depth between upstream and downstream 

reaches was significantly different across physiographic 

provinces (short culverts only), with the Upper Coastal Plain 

shifted to the right, indicating a greater difference in depth 

between the upstream and downstream reaches than in the 

Piedmont. Although differences were significant, they were 

not of substantial magnitude, with an average increase in 

depth of 0.17 m in Upper Coastal Plain downstream reaches 

and −0.12 m in Piedmont downstream reaches. The negative 

value indicates that, on average, the Piedmont downstream 

reaches were shallower than upstream reaches. No significant 

differences were observed between the culvert length classes 

for the Piedmont sites.

Table 3. Results of nonparametric tests on habitat complexity measured in upstream (US) and downstream (DS) reaches at selected 

culvert sites in South Carolina, 2016–18.

[Habitat complexity is defined as the number of geomorphic channel units per reach. CI, confidence interval]

Comparison Number of 

observations1

Upper 90% 

CI

Lower 90% 

CI p-value Pseudo-median/difference in location2

Wilcoxon signed-rank test

DS versus US complexity—Upper Coastal Plain 

short culverts

6/6 7.00 1.00 30.06 4.00

DS versus US complexity—Piedmont short 

culverts

7/7 4.00 −4.50 1 1.86e−05

DS versus US complexity—Piedmont long 

culverts

7/7 2.99 −1.50 1 2.49e−05

Wilcoxon rank-sum test

Difference in DS and US reach complexity—

Upper Coastal Plain short culverts versus 

Piedmont short culverts

6/7 8.99 0.99 30.09 3.00

Difference in DS and US reach complexity—

Piedmont long culverts versus short culverts

7/7 4.99 −3.00 0.95 −4.94e−05

1Number of observations in each group in the comparison.

2Pseudo-median for the Wilcoxon signed-rank test and difference in location for Wilcoxon rank-sum test. These values represent the approximate median of 

the differences between groups.

3Significant at the 90-percent confidence level.
Habitat and Geomorphic Characterization 13

Site identification

Piedmont long Piedmont short Upper Coastal Plain short

Channel−full cross−sectional area z−score

centercr

enoree

millersfk

t2rockcr

t2taylorcr

taylorcr

timscrk

bluebr

drycrk

indiancr

lilhogskin

beaverdam

trib2allison

trib2payne

cowbr

sadler

tinker

trib4hole

trueblue

bigpinetree

−2

−3

−1

0

2

3

4

1

EXPLANATION

1.5 times the interquartile range

above the box

>1.5 times the interquartile range

beyond either end of the box 

75th percentile

1.5 times the interquartile range

below the box

25th percentile

Downstream reach

Upstream reach

Median (50th percentile)

Interquartile

range

Figure 5. Boxplots showing the distribution of channel-full cross-sectional area z-scores for upstream and downstream 

reaches at selected culvert sites in South Carolina, 2016–18. Each panel represents a combination of physiographic province 

and culvert length class: Piedmont long culverts, Piedmont short culverts, and Upper Coastal Plain short culverts.
14 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

The width-to-depth ratio was also evaluated as an 

indicator of changes in channel shape between upstream and 

downstream reaches (fig. 7). This variable can indicate 

which dimension may be dominating the change in crosssectional area. Large values indicate a relatively wide and 

shallow channel, whereas small values indicate a relatively 

narrow and deep channel. Upper Coastal Plain sites had a 

reduced mean channel-full width-to-depth ratio downstream 

from the culvert, indicating a deeper and (or) narrower 

channel shape, at five of the six sites. The Piedmont sites 

were highly variable; at five of the seven short culverts, 

channels were deeper and (or) narrower downstream, but the 

opposite effect was observed at the long culverts (channels 

were wider and [or] shallower downstream at five of the seven 

sites). Wilcoxon rank tests, however, showed no significant 

differences in width-to-depth ratios within or among any of 

the strata. This result was unexpected given the differences 

in cross-sectional area and depth in the Upper Coastal Plain 

and indicates that any channel enlargement was not consistent 

in one dimension and included both lateral and vertical 

adjustments.

Table 4. Results of nonparametric tests on mean channel-full cross-sectional area z-scores for upstream (US) and downstream (DS) 

reaches at selected culvert sites in South Carolina, 2016–18.

[CI, confidence interval]

Comparison Number of 

observations1

Upper 90% 

CI

Lower 90% 

CI p-value Pseudo-median/difference in location2

Wilcoxon signed-rank test

DS versus US mean channel-full cross-sectional 

area z-score—Upper Coastal Plain short 

culverts

6/6 1.73 0.23 30.06 0.82

DS versus US mean channel-full cross-sectional 

area z-score—Piedmont short culverts

7/7 0.45 −0.49 0.81 −0.01

DS versus US mean channel-full cross-sectional 

area z-score—Piedmont long culverts

7/7 1.07 −0.17 0.29 0.32

Wilcoxon rank-sum test

Difference in DS and US mean channel-full 

cross-sectional area z-score—Upper Coastal 

Plain short culverts versus Piedmont short 

culverts

6/7 1.42 0.22 30.03 0.98

Difference in DS and US mean cross-sectional 

area channel-full z-score—Piedmont long 

culverts versus short culverts

7/7 0.96 −0.36 0.56 0.35

1Number of observations in each group in the comparison.

2Pseudo-median for the Wilcoxon signed-rank test and difference in location for the Wilcoxon rank-sum test. These values represent the approximate median 

of the differences between groups.

3Significant at the 90-percent confidence level.
Habitat and Geomorphic Characterization 15

Piedmont long Piedmont short Upper Coastal Plain short

Site identification

centercr

enoree

Millersfk

t2rockcr

t2taylorcr

taylorcr

timscrk

bluebr

drycrk

indiancr

lilhogskin

beaverdam

trib2allison

trib2payne

cowbr

sadler

tinker

trib4hole

trueblue

bigpinetree

Channel−full depth z−score −2

−3

−4

−1

0

2

3

1

EXPLANATION

1.5 times the interquartile range

above the box

>1.5 times the interquartile range

beyond either end of the box 

75th percentile

1.5 times the interquartile range

below the box

25th percentile

Downstream reach

Upstream reach

Median (50th percentile)

Interquartile

range

Figure 6. Boxplots showing the distribution of channel-full depth z-scores for upstream and downstream reaches at selected 

culvert sites in South Carolina, 2016–18. Each panel represents a combination of physiographic province and culvert length 

class: Piedmont long culverts, Piedmont short culverts, and Upper Coastal Plain short culverts.
16 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Table 5. Results of nonparametric tests on mean channel-full depth z-scores for upstream (US) and downstream (DS) reaches at 

selected culvert sites in South Carolina, 2016–18.

[CI, confidence interval]

Comparison Number of 

observations1

Upper 90% 

CI

Lower 90% 

CI p-value Pseudo-median/difference in location2

Wilcoxon signed-rank test

DS versus US mean channel-full depth 

z-score—Upper Coastal Plain short culverts

6/6 1.70 0.16 30.06 1.15

DS versus US mean channel-full depth 

z-score—Piedmont short culverts

7/7 0.39 −0.80 0.47 −0.28

DS versus US mean channel-full depth 

z-score—Piedmont long culverts

7/7 1.21 −0.41 0.38 0.50

Wilcoxon rank-sum test

Difference in DS and US mean channel-full 

depth z-score—Upper Coastal Plain short 

culverts versus Piedmont short culverts

6/7 2.07 0.37 30.05 1.40

Difference in DS and US mean channel-full 

depth z-score—Piedmont long culverts versus 

short culverts

7/7 0.96 −0.36 0.56 0.35

1Number of observations in each group in the comparison.

2Pseudo-median for the Wilcoxon signed-rank test and difference in location for the Wilcoxon rank-sum test. These values represent the approximate median 

of the differences between groups.

3Significant at the 90-percent confidence level.
Habitat and Geomorphic Characterization 17

Piedmont long Piedmont short Upper Coastal Plain short

Site identification

centercr

enoree

millersfk

t2rockcr

t2taylorcr

taylorcr

timscrk

bluebr

drycrk

indiancr

lilhogskin

beaverdam

trib2allison

trib2payne

cowbr

sadler

tinker

trib4hole

trueblue

bigpinetree

Width-to-depth ratio

7.5

5.0

2.5

0

10.0

17.5

22.5

15.0

12.5

20.0

EXPLANATION

1.5 times the interquartile range

above the box

>1.5 times the interquartile range

beyond either end of the box 

75th percentile

1.5 times the interquartile range

below the box

25th percentile

Downstream reach

Upstream reach

Median (50th percentile)

Interquartile

range

Figure 7. Boxplots showing the distribution of channel-full width-to-depth ratio for upstream and downstream reaches at 

selected culvert sites in South Carolina, 2016–18. Each panel represents a combination of physiographic province and culvert 

length class: Piedmont long culverts, Piedmont short culverts, and Upper Coastal Plain short culverts.
18 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Bed-Sediment Characteristics and Large Woody 

Debris

Pebble counts were conducted in the four sampling zones 

(fig. 2) at each Piedmont site to determine the distributional 

characteristics of the bed sediment in the areas where 

macroinvertebrates were collected. Bed-sediment particle 

sizes in the Upper Coastal Plain were not analyzed because of 

the dominance of sand and finer bed material. Median particle 

size (D50) from the 14 Piedmont sites ranged from 1 mm (the 

value assigned to sand and finer material), which was observed 

at multiple sites and zones, to 50.5 mm in the background 

zone at the site taylorcr. There were no clear trends between 

zones (that is, proximity to the culvert) and median particle 

size at any of the sites, regardless of culvert length (fig. 8). 

The prevalence of bedrock encountered during pebble counts 

was also evaluated. The greatest prevalence of bedrock was 

observed in the background zone at the site millersfk, which 

was 48 percent bedrock. Bedrock was not encountered at 

several sites. There were no observed patterns in bedrock 

prevalence related to zone or culvert length. Large woody 

debris also varied across reaches and sites and did not show 

any distinct trends between upstream or downstream reaches, 

by physiographic province or culvert length class (fig. 9).

Culvert Slope

Only 4 of the 20 sites had culvert slopes greater than 

2 percent, and they were distributed equally among long and 

short culverts, with only 1 site in the Upper Coastal Plain 

(fig. 10). Of these four sites (t2rockcr, millersfk, bigpinetree, 

trib2payne), t2rockcr had the greatest slope and perch height, 

as well as the greatest apparent effects downstream from 

the culvert. A consistent observation among these sites was 

that the culverts retained little to no sediment. Other sites 

that had culvert slopes less than 1 percent, however, also did 

not retain sediment, indicating that culvert slope is not the 

sole determinant of sediment retention. Furthermore, culvert 

slope was not a good indicator of culvert perching. Perching 

was observed at the culverts with the steepest slopes, as 

well as at culverts with slopes less than the streambed slope 

(for example, the site enoree). The observation of perching 

at culverts with low slopes could be the result of headward 

migration of a knickpoint (a part of a channel where there is a 

sharp change in slope) that was halted by the erosion-resistant 

culvert.

Ratio of Culvert Width to Bankfull Width

The ratio of culvert width to bankfull width at each 

transect was assessed to evaluate if constriction (or over 

widening) resulted in systematic changes in channel 

morphology. The ratio of culvert width to bankfull width at 

each transect was inconsistent at most sites. Across all sites, 

Kruskal-Wallis tests suggested no significant differences based 

on transect distance from the culvert. There were exceptions, 

such as the site t2rockcr, where the channel was three to 

five times wider than the culvert at transects 10 and 11, just 

downstream from the culvert. There were other differences 

that were substantial but not necessarily related to water 

flowing through the culvert. For example, at the sites bluebr 

and trib2payne, the bankfull width just upstream from the 

culvert (transect 12) was much wider than the culvert opening. 

Presumably, the widening was related to an acute approach 

angle, where the culvert was installed in a slight bend that led 

to bank erosion adjacent to the culvert wing wall on the cut 

bank side and subsequent channel enlargement. The culverts 

were narrower than the bankfull width at 11 sites and wider at 

9 sites. The greatest deviations were at site indiancr, where the 

culvert was 1.68 times wider than the mean bankfull width, 

and site trib2payne, where the culvert constricted flows to 

about one-half (0.47 percent) of the mean bankfull width. 

At several sites where multiple culvert boxes were present, 

sediment had accumulated in the secondary box to a level 

above the bankfull elevation, concentrating the flow to a 

single box for that flow level and below. This concentration 

of flow could lead to greater erosion during a small range of 

events, whereas lower frequency but high-magnitude events 

would contribute flow to the area in the second box above 

the sediment surface. Although the above results indicate 

a slightly greater prevalence of culvert opening widths 

that are narrower than bankfull widths, the morphological 

data characterizing the reach transects do not suggest that 

contemporaneous contraction scour is a widespread issue at 

the study sites.
Habitat and Geomorphic Characterization 19

Particle diameter, in millimeters

1 10 100 1,000

1 10 100 1,000

1 10 100 1,000

1 10 100 1,000

Particle diameter, in millimeters

0

25

50

75

100

0

25

50

75

100

0

25

50

75

100

0

25

50

75

100

Cumulative percent finer than

centercr beaverdam bluebr

Piedmont long Piedmont short

drycrk

enoree

indiancr

lilhogskin

millersfk t2rockcr

t2taylorcr trib2allison

trib2payne

taylorcr

timscrk

EXPLANATION

Zone

 Background (1)

 Upstream impact (2)

 Downstream impact (3)

 Recovery (4)

Figure 8. Graphs showing particle-size cumulative frequency distributions within each zone for the 14 Piedmont study sites. Zone 1 

is the background zone (at the upstream end of the reach, assumed to be relatively free from culvert effects). Zone 2 is the upstream 

impact zone (immediately upstream from the culvert). Zone 3 is the downstream impact zone (immediately downstream from the 

culvert). Zone 4 is the recovery zone (at the downstream end of the reach). Vertical lines at the 1-millimeter mark indicate that all bed 

particles in that zone were sand or finer material; some lines are obscured where all particles were sand or finer in more than one zone.
20 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

0

5

10

15

20

Reach

Downstream Upstream Downstream Upstream Downstream Upstream

Large woody debris volume, in cubic meters

Piedmont long Piedmont short Upper Coastal Plain short

EXPLANATION

1.5 times the interquartile range

above the box

>1.5 times the interquartile range

beyond either end of the box 

75th percentile

1.5 times the interquartile range

below the box

25th percentile

Downstream reach

Upstream reach

Median (50th percentile) 

Interquartile

range

Figure 9. Boxplots showing the distribution of large woody debris volume, aggregated to the reach 

level, at selected culvert locations in South Carolina, 2016–18. Each panel represents a combination 

of physiographic province and culvert length class: Piedmont long culverts, Piedmont short culverts, 

and Upper Coastal Plain short culverts.
Fish Community Characterization 21

Fish Community Characterization

A total of 3,968 fish specimens were collected, 

representing 44 species in 21 genera and 10 families (table 6). 

Of the total individuals caught, 82.2 percent were represented 

by 10 species: 5 species of minnows (family Cyprinidae), 

3 species of sunfishes (family Centrarchidae), and 1 species 

each of suckers (family Catostomidae) and mosquitofish 

(family Poeciliidae). The remaining 34 species ranged from 

0.03 to 1.66 percent of the total sample (number of individuals 

of each species ranging from 1 to 66). Because more sites 

were sampled in the Piedmont (14) than in the Upper Coastal 

Plain (6), more fish specimens were captured in the Piedmont 

than in the Upper Coastal Plain (3,142 and 826 fish specimens, 

respectively).

A prominent geographic separation was apparent for 26 

of the species, with 15 captured only at sites in the Piedmont 

physiographic province and 11 captured only at sites in the 

Upper Coastal Plain; 18 species were common to both the 

Piedmont and the Upper Coastal Plain (table 6). Of the 10 

most abundant fish species, 5 were collected in only one 

physiographic province; 4 of these species were confined to 

the Piedmont (the percent composition of total number of fish 

caught from both physiographic provinces is in parentheses): 

Nocomis leptocephalus (15.93 percent), Notropis lutipinnis

(5.92 percent), Lepomis cyanellus (5.65 percent), and Notropis 

chlorocephalus (3.05 percent). The sixth most common 

species, Pteronotropis stonei (5.80 percent) was found only in 

the Upper Coastal Plain. The second to fourth most abundant 

species were collected in both physiographic provinces: 

Lepomis auritus (15.47 percent), Semotilus atromaculatus

(14.79 percent), and Lepomis macrochirus (7.69 percent)—

all were collected in greater numbers in the Piedmont, 

partly because more sites were sampled and that province 

presumably had greater habitat suitability than the Upper 

Coastal Plain. The other 2 species represented among the 

10 most abundant were also collected in both physiographic 

provinces: Gambusia holbrooki (5.22 percent) and Erimyzon 

oblongus (2.67 percent)—more individuals of both species 

were collected in the Piedmont because they were present 

in many stream reaches and were found at a few reaches in 

especially high abundance.

Piedmont long Piedmont short Upper Coastal Plain short

Site identification

centercr

drycrk

enoree

millersfk

t2rockcr

t2taylorcr

taylorcr

timscrk

bluebr

indiancr

lilhogskin

beaverdam

trib2allison

trib2payne

cowbr

sadler

tinker

trib4hole

trueblue

bigpinetree

0

0.010

0.005

0.015

0.025

0.020

0.030

Slope

Upstream reach

Culvert

Downstream reach

EXPLANATION

Figure 10. Graph showing the slope of culvert bottom and stream thalweg in upstream and downstream reaches at selected 

culvert sites in South Carolina, 2016–18. Each panel represents a combination of physiographic province and culvert length 

class: Piedmont long culverts, Piedmont short culverts, and Upper Coastal Plain short culverts.
22 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Table 6. Fish species collected at selected culvert sites in South Carolina, 2016–18, physiographic province, number of sites, number 

of reaches where each species was collected, number of specimens, and percent composition of total sample.

[Shading indicates the 10 most abundant species, which represent 82.2 percent of all fish captured. x, species captured in that physiographic province; —, not 

applicable or species not captured in that physiographic province]

Species Common name

Upper 

Coastal 

Plain

Piedmont No. of

sites

No. of 

reaches

No. of 

specimens

Percent 

composition

Family Anguillidae

Anguilla rostrata American eel x — 1 2 19 0.48

Family Cyprinidae

Clinostomus funduloides Rosyside dace — x 2 3 51 1.29

Hybognathus regius Eastern silvery minnow — x 1 2 5 0.13

Hybopsis hypsinotus Highback chub — x 3 5 59 1.49

Hybopsis rubrifrons Rosyface chub — x 2 3 12 0.30

Nocomis leptocephalus Bluehead chub — x 11 20 632 15.93

Notemigonus crysoleucas Golden shiner x x 5 6 30 0.76

Notropis chlorocephalus Greenhead shiner — x 4 8 121 3.05

Notropis cummingsae Dusky shiner — x 2 2 4 0.10

Notropis hudsonius Spottail shiner — x 2 2 6 0.15

Notropis lutipinnis Yellowfin shiner — x 2 4 235 5.92

Notropis petersoni Coastal shiner x x 3 3 19 0.48

Notropis procne Swallowtail shiner — x 1 1 3 0.08

Pteronotropis stonei Lowland shiner x — 4 7 230 5.80

Semotilus atromaculatus Creek chub x x 11 20 587 14.79

Family Catostomidae

Erimyzon oblongus Creek chubsucker x x 10 15 106 2.67

Erimyzon sucetta Lake chubsucker x — 1 1 1 0.03

Family Ictaluridae

Ameiurus brunneus Snail bullhead x x 4 5 8 0.20

Ameiurus natalis Yellow bullhead x x 13 16 37 0.93

Ameiurus nebulosus Brown bullhead x x 3 5 10 0.25

Noturus gyrinus Tadpole madtom x — 1 1 2 0.05

Noturus insignis Margined madtom x x 5 9 39 0.98

Family Esocidae

Esox americanus Grass pickerel x x 7 13 63 1.59

Esox niger Chain pickerel x — 1 2 11 0.28

Family Aphredoderidae

Aphredoderus sayanus Pirate perch x x 7 10 36 0.91

Family Fundulidae

Fundulus lineolatus Lined topminnow x — 1 2 10 0.25

Family Poeciliidae

Gambusia holbrooki Eastern mosquitofish x x 9 15 207 5.22

Family Centrarchidae

Acantharchus pomotis Mud sunfish x — 1 1 1 0.03

Enneacanthus chaetodon Blackbanded sunfish x — 1 1 6 0.15

Enneacanthus gloriosus Bluespotted sunfish x — 2 2 8 0.20

Lepomis auritus Redbreast sunfish x x 18 33 614 15.47
Fish Community Characterization 23

The occurrence of fish species among sites and reaches 

was highly variable. The number of sites where a species was 

collected ranged from 1 to 18 and averaged 4.5 (table 6). Ten 

species were found at a single site; half of those were collected 

in both upstream and downstream reaches, and the other 

half were collected in only one reach. Of the total 44 species 

collected, 32 were found at no more than five sites and 

9 species were found at only one or two sites. Each species 

was collected in at least 1 reach and at most 33 reaches; 

28 species were found in 6 reaches or fewer.

The values of the Shannon-Wiener diversity index (S–W, 

log10) for fish per reach ranged from 0.16 to 1.04 among all 

sites, excluding the downstream reach at site drycrk, which 

had only one species (fig. 11). At 4 of the 6 Upper Coastal 

Plain sites and 8 of the 14 Piedmont sites, the downstream 

reach S–W value was higher than that of the upstream reach 

(fig. 11). Despite this possible trend, there were no significant 

differences between upstream and downstream S–W values 

across culvert categories, nor were there differences in the 

other diversity metrics examined for fish, Pielou’s evenness 

and Simpson’s diversity (dominance) index, based on 

Wilcoxon signed-rank tests.

A resemblance matrix of fish C/f (catch per unit effort; 

Hubert and Fabrizio, 2007) data was input into PRIMER for 

further analysis. The results of a global ANOSIM analysis 

of this resemblance matrix revealed a significant difference 

among groups (test statistic [R]=0.273; p=0.01). Individual 

pairwise comparisons of the ANOSIM test statistic showed 

significant differences between eight strata (R ranging from 

0.472 to 0.765), but each of these pairwise differences was 

between a reach and culvert length combination of separate 

Upper Coastal Plain and Piedmont sites. A SIMPROF test 

in PRIMER indicated general separation of sites largely 

by physiographic province (fig. 12; test statistic [π]=3.46, 

p=0.01). There was complete separation of Piedmont and 

Upper Coastal Plain sites in the nonmetric multidimensional 

scaling (nMDS) plot with a moderate 2D stress level of 0.15 

(fig. 13); however, there was no organized grouping of the 

fish assemblages among sites within either physiographic 

province. On the basis of the hierarchical cluster analysis, 

the sites beaverdam and drycrk grouped together and were 

separated from all other sites in the Piedmont. Both sites 

centercr and indiancr grouped with Upper Coastal Plain sites. 

Among all Piedmont sites, centercr and indiancr are closest to 

the boundary between the physiographic provinces and thus 

have more fish species in common with the Upper Coastal 

Plain sites.

Table 6. Fish species collected at selected culvert sites in South Carolina, 2016–18, physiographic province, number of sites, number 

of reaches where each species was collected, number of specimens, and percent composition of total sample.—Continued

[Shading indicates the 10 most abundant species, which represent 82.2 percent of all fish captured. x, species captured in that physiographic province; —, not 

applicable or species not captured in that physiographic province]

Species Common name

Upper 

Coastal 

Plain

Piedmont No. of

sites

No. of 

reaches

No. of 

specimens

Percent 

composition

Family Centrarchidae—Continued

Lepomis cyanellus Green sunfish — x 6 10 224 5.65

Lepomis gibbosus Pumpkinseed — x 2 3 33 0.83

Lepomis gulosus Warmouth x x 7 11 66 1.66

Lepomis macrochirus Bluegill x x 13 20 305 7.69

Lepomis marginatus Dollar sunfish x — 3 6 16 0.40

Lepomis microlophus Redear sunfish x x 3 3 11 0.28

Lepomis punctatus Spotted sunfish x — 3 5 31 0.78

Micropterus salmoides Largemouth bass x x 10 14 31 0.78

Family Percidae

Etheostoma collis Carolina darter — x 5 7 18 0.45

Etheostoma fusiforme Swamp darter x x 2 2 2 0.05

Etheostoma hopkinsi Christmas darter — x 2 4 23 0.58

Etheostoma olmstedi Tessellated darter x x 5 6 34 0.86

Etheostoma thalassinum Seagreen darter — x 1 2 2 0.05

Total — 28 32 — — 3,968 100
24 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

0

0.25

0.5

0.75

1.00

1.25

Shannon-Wiener diversity index (log10)

Piedmont long Piedmont short Upper Coastal Plain short

centercr

enoree

millersfk

t2rockcr

t2taylorcr

taylorcr

timscrk

bluebr

drycrk

indiancr

lilhogskin

beaverdam

trib2allison

trib2payne

cowbr

sadler

tinker

trib4hole

trueblue

bigpinetree

Site identification

Downstream reach

Upstream reach

EXPLANATION

Figure 11. Graph showing Shannon-Wiener diversity index values for fish communities sampled at selected culvert sites in 

South Carolina, 2016–18.
Fish Community Characterization 25

0 20 40 60 80 100

Percent similarity

t2taylorcr

t2rockcr

bluebr

trib2allison

millersfk

lilhogskin

timscrk

taylorcr

trib2payne

enoree

drycrk

beaverdam

indiancr

centercr

sadler

trib4hole

tinker

trueblue

cowbr

bigpinetree

Site identification

Physiographic province

 Piedmont

 Upper Coastal Plain

EXPLANATION

Figure 12. Hierarchical clustering dendrogram of selected culvert sites in South Carolina, with 

upstream and downstream reaches combined, created by using group-averaging Bray-Curtis 

similarities calculated from square-root transformed catch per unit effort data for fish samples. 

The vertical dashed line indicates 32-percent resemblance. Black horizontal lines indicate 

significant multivariate structure; there is no evidence from the Plymouth Routines in Multivariate 

Ecological Research (PRIMER) similarity profile (SIMPROF) test to support the detailed clustering 

structure shown by red lines.
26 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Fish species richness at each site (downstream and 

upstream reaches combined) ranged from 4 to 17 and averaged 

10. The most fish species were captured at the sites bigpinetree 

and sadler, 17 species each, and the fewest were captured at 

sites drycrk and millersfk, 4 species each (fig. 14). At 12 sites, 

more species were captured in the downstream reach than 

the upstream reach. At five sites, more species were captured 

upstream from the culvert than downstream, and at three 

sites, an equal number of species was caught in both reaches. 

The largest difference between reaches at a single site was 

observed at site bigpinetree, where 16 fish species were caught 

downstream from the culvert but only 7 were caught upstream. 

The fewest species found in a single reach was at the site 

drycrk, where one species, Gambusia holbrooki, was captured 

in the downstream reach. At all other sites, the difference in 

the number of species between upstream and downstream 

reaches was less than or equal to 3. There was a possible 

trend of more species captured at downstream reaches than 

upstream reaches within both physiographic provinces. For the 

Upper Coastal Plain, four sites had two to nine more species 

downstream from the culvert than upstream, one site had an 

equal number, and one site had one more species upstream 

than downstream. For the Piedmont, 8 of the 14 sites had one 

to three more species downstream than upstream from the 

culvert, 2 sites had an equal number, and 4 sites had two to 

three more species in the upstream reach than downstream. To 

test for possible differences in fish species richness between 

downstream and upstream reaches while factoring in culvert 

length and physiographic province, a series of nonparametric 

comparisons was made by using the difference in number 

of species between test categories (table 7); no significant 

differences were found across all culvert categories.

A SIMPROF test of all fish C/f data in PRIMER with 

downstream and upstream reaches separated revealed general 

clustering similar to that found by the analysis with reaches 

combined for each site (fig. 15; π=3.73, p=0.01). Three 

groups were distinguished at a 26-percent resemblance level 

(see solid horizontal lines bisected by a vertical dashed line 

in fig. 15): (1) sites beaverdam and drycrk; (2) most of the 

Piedmont sites, and; (3) all Upper Coastal Plain sites plus sites 

centercr and indiancr, the two Piedmont sites geographically 

closest to the physiographic province boundary (fig. 1). The 

sites beaverdam and drycrk were distinct from each other 

and all other sites. Eight fish species were collected at site 

beaverdam but only four at site drycrk, and these two sites 

had only a single species in common, Gambusia holbrooki. At 

these two sites, G. holbrooki was much more abundant than 

other species and was more abundant than G. holbrooki at all 

other sites, accounting for why the two sites clustered together. 

There was no support for multivariate structuring among sites 

in the Piedmont, but there was additional structuring within 

the Upper Coastal Plain cluster. At a 30-percent resemblance 

level, the sites bigpinetree, cowbr, trueblue, and tinker formed 

a group separate from a group consisting of sites sadler, 

trib4hole, centercr, and indiancr. Additionally, site sadler was 

distinct from the cluster of sites trib4hole and centercr, and 

site indiancr was distinct from these three sites. The nMDS 

ordination of all reaches and sites allows visualization of the 

seven clusters for which the SIMPROF test demonstrated 

statistical support (fig. 16); however, the nMDS ordination had 

moderately high 2D stress (0.17).

beaverdam

bigpinetree

bluebr

centercr

cowbr

drycrk

enoree

indiancr

lilhogskin millersfk

sadler

t2rockcr

t2taylorcr

taylorcr

timscrk

tinker

trib2allison

trib2payne

trib4hole trueblue

2D stress: 0.15

Physiographic province

 Piedmont

 Upper Coastal Plain

EXPLANATION

Figure 13. Two-dimensional (2D) nonmetric multidimensional scaling (nMDS) plot of fish catch per unit effort data for selected 

culvert sites in South Carolina factored by physiographic province; upstream and downstream reaches are combined for each 

site. Ordination is based on a square-root transformed Bray-Curtis similarity matrix.
Fish Community Characterization 27

A set of 15 habitat variables was used to evaluate possible 

linkages between abiotic factors and the fish assemblage 

groupings identified by the SIMPROF procedure by using 

the constrained (two-way) BEST routine with the Spearman 

rank correlations method in PRIMER. Draftsman plots were 

examined to confirm that the selected habitat variables were 

not correlated with others, and variables were normalized 

prior to ordination. The results of the global BEST analysis 

indicated a general relation between fish communities and 

habitat variables (Spearman rank correlation coefficient 

[ρ]=0.38; p=0.01). Six habitat variables provided the best 

combined correlations to account for the major groupings of 

fish assemblages by site (fig. 12): mean wetted depth, mean 

canopy closure, mean velocity, percentage of riffle habitat, 

percentage of pool habitat, and LWD volume.

To further explore for possible relations between fish 

C/f and habitat variables among sites and reaches, additional 

BEST routines were run for Upper Coastal Plain sites and 

reaches and independently for Piedmont long and short 

culvert sites and reaches. The results of these tests provided 

no statistical support for relating habitat variables to biotic 

assemblages (table 8). The habitat variables that provided the 

best correlations varied considerably among the combinations 

of physiographic province, culvert length, and upstream or 

downstream reach. In terms of accounting for the greatest 

correlation between habitat variables and fish communities, 

mean reach wetted width was the only habitat variable 

common to all combinations of physiographic province, 

culvert length, and reach. Other abiotic parameters common 

to two or more combinations of strata included mean reach 

wetted depth, percent of reach that was either run or pool, 

mean reach velocity, total reach volume of LWD, and 

culvert slope.

0

5

10

15

20

Number of species

Piedmont long Piedmont short Upper Coastal Plain short

centercr

enoree

millersfk

t2rockcr

t2taylorcr

taylorcr

timscrk

bluebr

drycrk

indiancr

lilhogskin

beaverdam

trib2allison

trib2payne

cowbr

sadler

tinker

trib4hole

trueblue

bigpinetree

Site identification

Downstream reach

Upstream reach

Site total

EXPLANATION

Figure 14. Bar graph showing the taxonomic richness of fish species collected at selected culvert sites in South Carolina.
28 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

The restriction of over one-half of the fish species to sites 

within a single physiographic province and the results of the 

SIMPROF and BEST tests confounded multivariate analyses 

to explore trends in the fish community data. In general, 

upstream and downstream reaches for nearly all sites clustered 

together, indicating that reaches at the same site were more 

closely related to each other than to reaches at other sites. The 

sites bigpinetree and trueblue were exceptions. At bigpinetree, 

this result was primarily attributable to the collection of a suite 

of lowland species that were concentrated near the culvert in 

an open-canopy area of the downstream reach where there 

was a thick bed of aquatic macrophytes. The culvert slope 

at bigpinetree was high, potentially limiting movement from 

downstream to upstream. Like bigpinetree, the occurrence 

and abundance of several fish species were notably different 

between the downstream and upstream reaches at site trueblue. 

The site trueblue also had a high culvert slope, shallow water 

depth in the culvert, and a large riprap cascade downstream 

from the culvert, which possibly limited fish movement from 

downstream to upstream.

Table 7. Results of nonparametric tests of fish species richness between downstream and upstream reaches by physiographic 

province.

Comparison Number of observations p-value

Wilcoxon signed-rank test with continuity correction

Upper Coastal Plain short culverts: downstream versus upstream 6/6 0.104

Piedmont short culverts: downstream versus upstream 7/7 0.730

Piedmont long culverts: downstream versus upstream 7/7 0.272

Wilcoxon rank-sum test with continuity correction

Difference in upstream and downstream reaches: Upper Coastal Plain short culverts versus 

Piedmont short culverts

6/7 0.128

Difference in upstream and downstream reaches: Piedmont long culverts versus short culverts 7/7 0.475
Fish Community Characterization 29

0 20 40 60 80 100

Percent similarity

drycrk_up

drycrk_dn

beaverdam_up

beaverdam_dn

timscrk_up

timscrk_dn

trib2payne_dn

taylorcr_up

taylorcr_dn

lilhogskin_up

lilhogskin_dn

t2rockcr_up

t2rockcr_dn

millersfk_up

millersfk_dn

trib2allison_up

trib2allison_dn

trib2payne_up

enoree_up

enoree_dn

t2taylorcr_up

t2taylorcr_dn

bluebr_up

bluebr_dn

indiancr_up

indiancr_dn

centercr_up

centercr_dn

trib4hole_up

trib4hole_dn

sadler_up

sadler_dn

tinker_up

tinker_dn

trueblue_up

cowbr_up

cowbr_dn

trueblue_dn

bigpinetree_dn

bigpinetree_up

Sample identification

Physiographic province

 Piedmont

 Upper Coastal Plain

EXPLANATION

Figure 15. Hierarchical clustering dendrogram of downstream (dn) and upstream (up) reaches at selected culvert sites 

in South Carolina, created by using group-averaging Bray-Curtis similarities calculated from square-root transformed 

catch per unit effort data for fish samples. The vertical dashed line indicates 26-percent resemblance. Black horizontal 

lines indicate significant multivariate structure; there is no evidence from the Plymouth Routines in Multivariate Ecological 

Research (PRIMER) similarity profile (SIMPROF) test to support the detailed clustering structure shown by red lines.
30 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

beaverdam_dn

beaverdam_up

bigpinetree_dn

bigpinetree_up

bluebr_dn

bluebr_up

centercr_dn

centercr_up

cowbr_dn

cowbr_up

drycrk_dn

drycrk_up

enoree_dn

enoree_up indiancr_dn

indiancr_up

lilhogskin_dn

lilhogskin_up

millersfk_dn

millersfk_up

sadler_dn

sadler_up

t2rockcr_dn

t2rockcr_up

t2taylorcr_dn

t2taylorcr_up

taylorcr_dn

taylorcr_up

timscrk_dn

timscrk_up

tinker_dn

tinker_up

trib2allison_dn

trib2allison_up

trib2payne_dn

trib2payne_up

trib4hole_dn

trib4hole_up

trueblue_dn

trueblue_up

2D stress: 0.17

Figure 16. Two-dimensional (2D) nonmetric multidimensional scaling (nMDS) plot of downstream (dn) and 

upstream (up) reaches for selected culvert sites in South Carolina. Ordination is based on group-averaging 

Bray-Curtis similarities calculated from square-root transformed fish catch per unit effort data. The different 

symbols represent the groups for which the Plymouth Routines in Multivariate Ecological Research (PRIMER) 

similarity profile (SIMPROF) test demonstrated statistical support (see fig. 15).

Table 8. Combinations of mean reach habitat variables that best match the fish community structure as measured by Spearman rank 

correlation test using the Bio-Env + Stepwise (BEST) routine in Plymouth Routines in Multivariate Ecological Research (PRIMER).

Physiographic province, 

culvert length, and reach

No. of 

variables Habitat variables Sample statistic (ρ) p-value

Piedmont, long, upstream 5 Wetted width, wetted depth, percent of reach that was run, 

percent of reach that was pool, total reach volume of 

LWD

0.579 0.283

Piedmont, long, downstream 3 Wetted width, velocity, number of GCUs per reach 0.596 0.524

Piedmont, short, upstream 5 Wetted width, canopy closure, channel-full area, culvert 

length, culvert slope

0.702 0.110

Piedmont, short, downstream 5 Wetted width, wetted depth, culvert length, culvert slope, 

total reach volume of LWD

0.755 0.100

Upper Coastal Plain, short, upstream 4 Wetted width, percent of reach that was pool, perch height 

of downstream culvert bottom, culvert slope

0.614 0.680

Upper Coastal Plain, short, downstream5 Wetted width, canopy closure, velocity, percent of reach 

that was run, percent of reach that was riffle

0.804 0.084
Macroinvertebrate Community Characterization 31

Macroinvertebrate Community 

Characterization

A total of 178 macroinvertebrate taxa were identified: 

121 common to both the Piedmont and Upper Coastal Plain 

physiographic provinces, 47 unique to the Piedmont, and 10 

unique to the Upper Coastal Plain. Data were subset into three 

categories: Piedmont long, Piedmont short, and Upper Coastal 

Plain short. A one-way analysis of similarities (ANOSIM) 

test was run to assess possible differences between the four 

sampling zones within each category. For all three categories, 

there were no significant differences (p less than 0.05) between 

zones. The nMDS ordinations for each category (fig. 17A–C) 

had moderate stress values in 2D space (Piedmont long, 0.2; 

Piedmont short, 0.21; Upper Coastal Plain short, 0.23), and 

these stress values improved in 3D space (Piedmont long, 

0.16; Piedmont short, 0.16; Upper Coastal Plain short, 0.15).

Because there was no apparent difference between zones 

within each category, a SIMPROF test was used to evaluate 

macroinvertebrate community similarities among all samples 

and samples within each category. When all macroinvertebrate 

samples were combined, there was no clear separation based 

on physiographic province; therefore, further discussion 

focuses on the three categories. A similarity threshold of 

65 percent was selected because it resulted in three distinct 

groups within each stratum and allowed for consistency in 

discussing patterns within and among categories. The three 

groups within a category are designated “A,” “B,” and “C” 

(from top to bottom, fig. 18A–C).

In the Piedmont long category, there were 10 samples in 

group A, 11 samples in group B, and 7 samples in group C. At 

three sites, three of the four samples were within one group 

and the least similar sample (similarity less than 65 percent) 

was collected adjacent to the culvert (upstream impact zone 

for sites enoree and t2taylorcr; downstream impact zone for 

site millersfk). In the Piedmont short category, there were 

11 samples in group A, 14 samples in group B, and 3 samples 

in group C. At four sites, three of the four samples were within 

one group and the least similar sample (similarity less than 

65 percent) was collected adjacent to the culvert (upstream 

impact zone for site trib2payne; downstream impact zone 

for sites beaverdam, bluebr, and lilhogskin). In the Piedmont 

short category, there were 18 samples in group A, 4 samples 

in group B, and 2 samples in group C. At two sites, three of 

the four samples were within one group and the least similar 

sample (similarity less than 65 percent) was collected adjacent 

to the culvert (downstream impact zone for sites bigpinetree 

and tinker).

For all three categories, most samples were in groups A 

and B (Piedmont long, 75 percent of samples; Piedmont short, 

89 percent; and Upper Coastal Plain short, 92 percent). For 

the Piedmont long and Piedmont short categories, the samples 

in groups A and B were essentially evenly distributed. In the 

Upper Coastal Plain category, 75 percent of the samples were 

in group A, indicating that 75 percent of the macroinvertebrate 

community assemblages in the Upper Coastal Plain were, at 

minimum, 65 percent similar. These results indicate that the 

overall macroinvertebrate community structure for samples 

within a category were more variable, or dissimilar, in the 

Piedmont (both long and short culverts) than in the Upper 

Coastal Plain. Each category had at least two sites where three 

of four samples grouped together (Piedmont long, three sites; 

Piedmont short, four sites; and Upper Coastal Plain short, 

two sites) and the least similar sample (similarity less than 

65 percent) was collected adjacent to the culvert. These results 

suggest that some of the macroinvertebrate communities may 

indeed be affected by culverts. Our study design, however, was 

not optimized to assess site-level differences, so additional 

samples collected over time would be needed to substantiate 

the significance of these relations.

The metrics used for this study were determined by 

assessing culvert-related studies on macroinvertebrate 

communities, comparable to existing biomonitoring 

programs in the southeastern United States. Metric values 

were based on percent abundances, unless otherwise 

indicated (appendix 1, table 1.1). The metrics were used 

to evaluate the macroinvertebrate communities by running 

the BEST procedure in PRIMER, resulting in a metric or 

combination of metrics that had the highest similarity to the 

macroinvertebrate community structure. Results are listed 

by all samples within a category and by each sampling 

zone within a category (table 9). When all samples within a 

category were combined, each category had a combination 

of metrics that were considered highly significant (p less 

than 0.001). Each metric was then individually evaluated by 

using the Wilcoxon rank-sum test to determine if the metric 

was significantly different among the four sampling zones: 

background (zone 1), upstream impact (zone 2), downstream 

impact (zone 3), and recovery (zone 4). Statistical tests failed 

to reject the null hypothesis of any significant difference 

(α=0.10) in distributions between pairs of samples. Among 

the four zones within each category (n=12), variability in the 

macroinvertebrate community structure was explained by a 

combination of metrics in only three zones: five metrics in 

Piedmont long background zone, four metrics in Piedmont 

long upstream impact zone, and six metrics in Upper Coastal 

Plain short recovery zone.
32 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

A. Piedmont long

Transform: Square root

Resemblance: S17 Bray-Curtis similarity

centercr1

centercr2

centercr3

centercr4

enoree1

enoree2

enoree3

enoree4

millersfk1

millersfk2

millersfk3

millersfk4

t2rockcr1

t2rockcr2

t2rockcr3

t2rockcr4

t2taylorcr1

t2taylorcr2

t2taylorcr3

t2taylorcr4

taylorcr1

taylorcr2

taylorcr3

taylorcr4

timscrk1

timscrk2

timscrk3

timscrk4

2D stress: 0.2

Zone

 Background (1)

 Upstream impact (2)

 Downstream impact (3)

 Recovery (4)

EXPLANATION

Figure 17. Two-dimensional (2D) nonmetric multidimensional scaling (nMDS) plots of macroinvertebrate assemblage data for 

samples collected in four zones at selected culvert sites in South Carolina. Ordination is based on a square-root transformed 

Bray-Curtis similarity matrix. A, Piedmont long culverts. B, Piedmont short culverts. C, Upper Coastal Plain short culverts.
Macroinvertebrate Community Characterization 33

Transform: Square root

Resemblance: S17 Bray-Curtis similarity

beaverdam1

beaverdam2

beaverdam3

beaverdam4

bluebr1

bluebr2

bluebr3

bluebr4

drycrk1

drycrk2 drycrk3

drycrk4

indiancr1

indiancr2

indiancr3

indiancr4

lilhogskin1

lilhogskin2

lilhogskin3

lilhogskin4

trib2allison1

trib2allison2

trib2allison3

trib2allison4

trib2payne1

trib2payne2 trib2payne3

trib2payne4

2D stress: 0.21

Zone

 Background (1)

 Upstream impact (2)

 Downstream impact (3)

 Recovery (4)

EXPLANATION

B. Piedmont short

Transform: Square root

Resemblance: S17 Bray-Curtis similarity

bigpinetree1

bigpinetree2

bigpinetree3

bigpinetree4

cowbr1

cowbr2 cowbr3

cowbr4

sadler1

sadler2

sadler3

sadler4

tinker1

tinker2

tinker3

tinker4

trib4hole1

trib4hole2

trib4hole3

trib4hole4

trueblue1

trueblue2

trueblue3

trueblue4

2D stress: 0.23

Zone

 Background (1)

 Upstream impact (2)

 Downstream impact (3)

 Recovery (4)

EXPLANATION

C. Upper Coastal Plain short

Figure 17. —Continued
34 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Transform: Square root

Zone Resemblance: S17 Bray-Curtis similarity

 Background (1)

 Upstream impact (2)

 Downstream impact (3)

 Recovery (4)

EXPLANATION

A. Piedmont long

50 60 70 80 90 100

Percent similarity

centercr4

millersfk3

t2taylorcr1

centercr2

taylorcr1

t2taylorcr3

t2taylorcr4

t2rockcr2

t2rockcr3

t2rockcr1

t2rockcr4

centercr3

enoree2

timscrk3

timscrk1

timscrk2

timscrk4

enoree3

taylorcr2

millersfk2

millersfk4

taylorcr3

millersfk1

t2taylorcr2

enoree4

taylorcr4

centercr1

enoree1

Sample identification

A

B

C

Figure 18. Hierarchical clustering dendrograms of samples collected in four zones at selected culvert sites in 

South Carolina, created by using group-averaging Bray-Curtis similarities calculated from square-root transformed 

macroinvertebrate abundance data. The vertical dashed lines indicate 65-percent resemblance. Black horizontal lines 

indicate significant (p less than 0.05) groups; red lines indicate a lack of significant groups. A, Piedmont long culverts. B, 

Piedmont short culverts. C, Upper Coastal Plain short culverts.
Macroinvertebrate Community Characterization 35

Transform: Square root

Resemblance: S17 Bray-Curtis similarity

Sample identification

Zone

 Background (1)

 Upstream impact (2)

 Downstream impact (3)

 Recovery (4)

EXPLANATION

beaverdam1

beaverdam2

beaverdam4

drycrk3

lilhogskin2

indiancr4

lilhogskin1

trib2allison4

drycrk1

lilhogskin4

bluebr3

trib2allison3

indiancr3

trib2payne4

indiancr2

trib2payne1

trib2payne3

bluebr4

drycrk2

drycrk4

lilhogskin3

bluebr1

bluebr2

indiancr1

trib2allison1

trib2payne2

beaverdam3

trib2allison2

B. Piedmont short

50 60 70 80 90 100

Percent similarity

A

B

C

Figure 18. —Continued
36 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

The AbundTOL metric is the abundance-weighted U.S. 

Environmental Protection Agency tolerance value calculated 

for each sample (appendix 1, table 1.2). Lenat (1993) created 

classification criteria for the Piedmont and Coastal Plain 

ecoregions and established five classes for AbundTOL values 

as follows: (1) less than or equal to 5.24, excellent; (2) 

5.25–5.95, good; (3) 5.96–6.67, good-fair; (4) 6.68–7.70, fair; 

and (5) greater than or equal to 7.71, poor. In the Piedmont 

long category, six of the seven sites had all samples in one 

class or in two consecutive classes; the exception was site 

trib2taylorcr, which had samples in three classes. Samples 

within sites were generally classified similarly; however, this 

was not the case among sites. For example, three samples at 

site enoree were classified as excellent, whereas three samples 

at site millersfk were fair. Of all the samples in the Piedmont 

long category, two were classified as poor: one sample Sample identification

C. Upper Coastal Plain short

Zone number

 Background (1)

 Upstream impact (2)

 Downstream impact (3)

 Recovery (4)

EXPLANATION

50 60 70 80 90 100

Percent similarity

Transform: Square root

Resemblance: S17 Bray-Curtis similarity

bigpinetree3

trib4hole4

trueblue1

tinker2

tinker1

tinker4

sadler1

sadler3

sadler2

sadler4

trueblue3

trib4hole2

cowbr3

trueblue2

cowbr1

trib4hole3

trueblue4

cowbr2

cowbr4

bigpinetree4

bigpinetree1

bigpinetree2

tinker3

trib4hole1

A

B

C

Figure 18. —Continued
Macroinvertebrate Community Characterization 37

collected at the top of a sampling reach (site millersfk1) and 

one just above a culvert (site t2taylorcr2). In the Piedmont 

short category, three sites had samples in two classes and four 

sites had samples in three classes. Unlike the Piedmont long 

category, two sites (drycrk and trib2payne) had samples in 

nonconsecutive classes without an intermediate classification. 

Piedmont short sites had sample classifications ranging from 

excellent to fair; no samples were classified as poor. The 

Upper Coastal Plain samples and sites scored differently 

than the Piedmont samples and sites. Three Upper Coastal 

Plain sites had all samples in the same class (cowbr, sadler, 

trueblue), and two sites had samples in two consecutive 

classes (bigpinetree and tinker). The only site with samples in 

three classes was trib4hole, which was also the only site that 

had samples classified as fair or good-fair. All other samples in 

the Upper Coastal Plain were either excellent or good.

Habitat variables at the zone level were examined, 

and correlated variables were eliminated after evaluating 

scatter plots. Eight habitat variables were selected to assess 

the macroinvertebrate communities by running the BEST 

procedure in PRIMER, resulting in a habitat variable or 

combination of variables that had the highest similarity to 

the macroinvertebrate community structure. Table 10 lists the 

results by sampling zone in each category. In the Piedmont 

physiographic province, there was only one significant 

relation (p less than 0.001) between habitat variables and the 

macroinvertebrate community. For Piedmont short samples 

collected in the upstream impact zone, the combination of 

canopy closure, channel-full area, mean velocity, and presence 

of bedrock best explained the community structure of those 

samples. In the Upper Coastal Plain short category, there also 

was only one significant relation (p less than 0.03), which 

was for samples collected in the recovery zone and was based 

solely on mean wetted width.

Table 9. Combinations of macroinvertebrate metrics that best match the macroinvertebrate community structure as measured by 

Spearman rank correlation test using the Bio-Env + Stepwise (BEST) routine in Plymouth Routines in Multivariate Ecological Research 

(PRIMER).

[Zone numbers: 1, background; 2, upstream impact; 3, downstream impact; 4, recovery]

Physiographic province, 

culvert length, and zone No. of variables Metrics Sample statistic (ρ) p-value

Piedmont, long, all 2 Abund, Margalef 0.611 0.001

Piedmont, long, 1 5 Abund, Pielou’s evenness, Simpson, Dom1, 

CHp

0.813 0.026

Piedmont, long, 2 4 Abund, Margalef, pOM_abund, CHp 0.804 0.023

Piedmont, long, 3 6 Rich, Margalef, Simpson, pPR_abund, 

pOM_abund, pSH_abund

0.662 0.077

Piedmont, long, 4 2 Rich, pSC_abund 0.651 0.139

Piedmont, short, all 5 AbundTOL, Abund, Margalef, pSH_abund, 

EPT_CHp

0.454 0.001

Piedmont, short, 1 1 pSH_abund 0.477 0.75

Piedmont, short, 2 1 Abund 0.744 0.21

Piedmont, short, 3 1 EPTR 0.564 0.269

Piedmont, short, 4 3 ShannonDiv, EPTR, EPT_CHp 0.847 0.293

Upper Coastal Plain, short, all 2 Abund, CHp 0.531 0.001

Upper Coastal Plain, short, 1 1 pOM_abund 0.639 0.648

Upper Coastal Plain, short, 2 1 EPT_CHp 0.693 0.423

Upper Coastal Plain, short, 3 3 Abund, pOM_abund, CHp 0.65 0.231

Upper Coastal Plain, short, 4 6 Abund, Rich, SimpsonDiv, pSC_abund, 

pSH_abund, EPT_CHp

0.868 0.028
38 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Role of Culverts in Shaping Channel 

Morphology, Aquatic Habitat, and 

Biotic Community Structure

The results of the geomorphic and in-stream habitat 

assessments indicate a high degree of variation within 

most sites, regardless of whether the reach was upstream or 

downstream from the culvert. This result was not entirely 

unexpected. When evaluating a rather short reach of stream, 

many stochastic processes, operating over different spatial and 

temporal scales, combine to make up the observed channel 

form at a particular location and time. If a consistent response 

was driven by culverts, the effect should have been detected 

in the upstream versus downstream analyses. An initial 

hypothesis was that any differences in channel form were 

more likely to be observed in the Piedmont, owing to the hilly 

topography, steeper slopes, and more clay-rich banks that may 

be prone to mass wasting (Simon and Rinaldi, 2006), than in 

the lower gradient and sandy Upper Coastal Plain streams. The 

opposite result, however, was observed. Although the Upper 

Coastal Plain has streams with lower gradients and generally 

greater access to overbank areas to dissipate flow energy, the 

placement of a berm across a once expansive floodplain forces 

naturally occurring low-velocity sheet flow into a narrower 

channel, which contributed to incision downstream from 

the culvert at five of the six sites. It is unknown how these 

findings may apply to pipes or other types of culverts. In a 

study focused on the North Carolina Piedmont, the greatest 

alteration to cross-sectional area was adjacent to pipe and 

arch culverts and sites with box culverts were the least altered 

(Merrill and Gregory, 2004; Merrill, 2005). In the current 

study, the lack of observed changes in the Piedmont could be 

partly due to a singular focus on box culverts but could also 

be somewhat attributed to past land disturbances that caused 

channels to be much larger than would be expected on the 

basis of drainage area and climate (Trimble, 1974; Dunne and 

Leopold, 1978; Doll and others, 2002).

Placing Current Geomorphic Settings in 

Perspective

Historical agricultural activities associated with initial 

European settlement have been implicated in dramatic changes 

to landscapes and aquatic systems across the Piedmont 

(Trimble, 1974; Walter and Merritts, 2008). Trimble (1974)

estimated that the entire southern Piedmont lost approximately 

19 centimeters of topsoil from 1700 to 1970 and that many 

stream channels were filled with sediment as deep as 3 m. 

When these stream channels filled in, the reduced capacity to 

transport water resulted in flooded valley bottoms until the 

streams could cut through the alluvium, once again forming 

a channel. Similarly, Jackson and others (2005) found a 

nearly uniform sediment deposit, 1.65 m thick, overlying a 

buried A horizon (top layer of mineral soil) in the Murder 

Creek watershed (Altamaha River Basin) in the Piedmont 

of Georgia. The absence of detectable culvert effects on 

physical habitat and channel morphology at the current South 

Table 10. Combinations of mean zone habitat variables that best match the macroinvertebrate community structure as measured by 

Spearman rank correlation test using the Bio-Env + Stepwise (BEST) routine in Plymouth Routines in Multivariate Ecological Research 

(PRIMER).

[Zone numbers: 1, background; 2, upstream impact; 3, downstream impact; 4, recovery]

Physiographic province, 

culvert length, and zone No. of variables Habitat variables Sample statistic (ρ) p-value

Piedmont, long, 1 5 Wetted width, canopy closure, velocity, particle 

size of the 84th percentile, bedrock

0.073 0.924

Piedmont, long, 2 2 Wetted width, canopy closure 0.403 0.358

Piedmont, long, 3 3 Wetted depth, velocity, bedrock 0.536 0.107

Piedmont, long, 4 4 Wetted width, velocity, particle size of the 84th 

percentile, bedrock

0.425 0.533

Piedmont, short, 1 1 Velocity 0.07 0.884

Piedmont, short, 2 4 Canopy closure, channel-full area, velocity, 

bedrock

0.926 0.001

Piedmont, short, 3 3 Channel-full area, velocity, bedrock 0.556 0.112

Piedmont, short, 4 3 Canopy closure, channel-full area, velocity 0.508 0.61

Upper Coastal Plain, short, 1 2 Wetted depth, channel-full area 0.368 0.719

Upper Coastal Plain, short, 2 1 Velocity 0.054 0.985

Upper Coastal Plain, short, 3 3 Wetted depth, canopy closure, channel-full area 0.55 0.191

Upper Coastal Plain, short, 4 1 Wetted width 0.786 0.03
Role of Culverts in Shaping Channel Morphology, Aquatic Habitat, and Biotic Community Structure 39

Carolina Piedmont study sites (long and short culverts) could 

be because many culverts were installed after substantial 

channel enlargement had already occurred; therefore, 

only the highest magnitude discharge events place enough 

stress on banks and beds to lead to further morphological 

changes. Incipient floodplain formation, the accumulation 

of sediments and debris that begin to collect and stabilize 

within the channel above the low-flow level, was observed 

at many of the Piedmont sites. On the basis of the channel 

evolution models of Schumm and others (1984) and Simon 

(1989), this observation would indicate that streams are in an 

aggregational phase, leading to an eventual morphology that 

represents a “channel within a channel” and high banks that 

represent terraces.

The South Carolina Piedmont sites can be placed in 

a broader context by comparing observed conditions with 

those derived from empirical relations based on drainage 

area. Bankfull elevation represents the point at which water 

is just contained within the defined channel, and bankfull 

discharge occurs, on average, once every 1.5 years (Dunne and 

Leopold, 1978). Harman and others (1999) found that in rural 

North Carolina Piedmont streams, the bankfull recurrence 

interval (RI) was 1.09–1.8 years. In incised streams, however, 

a channel-filling discharge event does not necessarily 

correspond to this range of RI and may be far less common. 

By using the RI or exceedance probability from streamflow 

records, it is possible to apply hydraulic geometry relations 

to streams in a similar setting to approximate a historical 

bankfull discharge and associated morphology on the basis of 

drainage area (for example, Doll and others, 2002). Assuming 

that hydraulic geometry relations developed for similar 

regions in North Carolina (Harman and others, 1999; Doll and 

others, 2002, 2003) are a fair approximation for the present 

study area, channel cross-sectional area at the South Carolina 

Piedmont sampling sites was, on average, 193 percent greater 

than would be expected for undisturbed streams with the same 

drainage area, thus highlighting the enlargement of channels at 

the Piedmont sites in this study.

Channel enlargement can directly affect stream habitat 

stability and biotic communities. High-energy conditions will 

be more frequent when flows cannot spill out of the channel 

onto the floodplain. This condition can be examined more 

explicitly by computing the maximum potential shear stress 

that would have been placed on the streambed and associated 

habitat and benthic communities during a bankfull flow event, 

assuming undisturbed conditions approximated by hydraulic 

geometry relations (Harman and others, 1999; Doll and 

others, 2002). Shear stress based on the present channel-full 

morphology was, on average, 150 percent greater than 

what would be expected in undisturbed channels where the 

bankfull level represents the top of the channel, demonstrating 

the importance of floodplain connectivity for overbank 

flow and energy dissipation. The large increase in channel 

cross-sectional area, which results in increased energy and 

shear stress for moderate- to low-frequency flow events, could 

explain why no culvert effects were observed in the Piedmont. 

Alternatively, if culverts are adequately sized to allow passage 

of moderate flood discharges, are properly installed with a 

slope similar to that of the streambed, and have buried inverts 

(bottom edge of culvert), then under normal conditions, 

culverts should not affect the continuity of water and sediment 

and, therefore, should not lead to persistent geomorphic or 

habitat alterations.

An additional concern, especially in the Piedmont, is 

that even if a culvert effect was observed, there was some 

uncertainty regarding the disturbance propagation. Were 

changes in morphology downstream from the culvert induced 

by scour because of an undersized or over-sloped culvert, or 

were differences driven by larger-scale adjustment processes, 

such as upstream knickpoint migration? With the present data, 

it is not possible to isolate a sole disturbance, but on the basis 

of culvert characteristics and overall site-level conditions, it 

seems likely that a combination of factors are involved. Many 

of the Piedmont culverts are wider than the stream channels, 

and perching, although not widespread, was observed across 

the range of culvert slopes. These characteristics suggest 

that broad-scale adjustments may be the dominant factor, 

where streams channels are still adjusting to past disturbances 

and stream morphology has yet to reestablish equilibrium 

(Trimble, 1977; Simon, 1989).

Effects of Box Culverts on Habitat and Biotic 

Communities

Although past studies have found that bridges and 

culverts can impede LWD transport (Lassettre and Kondolf, 

2012), we did not find that to be the case in the current 

study. Owing to the headwater nature of most streams in the 

current study, the variability in LWD volume and density 

may simply reflect recruitment variation and have less to do 

with transport mechanisms. Although there were a few sites 

where the culvert obviously interrupted the transport of LWD 

(sites millersfk, indiancr, and centercr), the infrequent flow 

magnitude needed to move LWD in these small headwater 

channels likely has a larger role than the culvert acting as a 

constriction or barrier.

Several studies that evaluated bed-sediment size 

distributions in relation to culverts have reported increased 

fine sediment either immediately below or above the culvert 

compared to adjacent stream reaches (Wellman and others, 

2000; Khan and Colbo, 2008; Peterson, 2010; MacPherson 

and others, 2012). This effect was not observed at the 

Piedmont sites, and the response was highly variable with 

no consistent trend. This result likely reflects the controls of 

local geology and disturbance history, which may influence 

the retention or flushing of fine sediment. Both LWD and 

bed-sediment size are important habitat elements for fish and 

macroinvertebrates, but they showed little correlation in the 

current study.
40 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

A large body of evidence corroborates the myriad effects 

of culverts on fish species and communities (Hotchkiss and 

Frei, 2007; Cocchiglia and others, 2012). At the species or 

population level, much of the focus has been on how culverts 

affect fish movement or disrupt passage, specifically how 

these structures impede dispersal or create unfavorable 

conditions through alteration of habitats, hydrology, and 

fluvial connectivity. Mark-recapture methods are commonly 

applied to assess bidirectional movement of fish through 

culverts (Warren and Pardew, 1998; Huser, 2009; Norman 

and others, 2009; Bouska and Paukert, 2010; Briggs and 

Galarowicz, 2013). Additionally, as in our study, most 

investigations of barriers to fish movement associated with 

roadways involve sampling fish upstream and downstream 

from culverts or other structures. In many studies, the focus 

has been on comparing different types of structures—for 

example, box culverts, bottomless box culverts, pipe culverts, 

bridges, and so on—in terms of how they affect fish movement 

or alter habitat. These studies often include physical habitat 

measurements to ascertain which conditions affect fish passage 

or community composition (Gibson and others, 2005; Bouska 

and others, 2010; MacPherson and others, 2012; Briggs and 

Galarowicz, 2013; Favaro and others, 2014). Other studies 

examined swimming performance or behavior of fish in 

simulated streams (Kemp and Williams, 2008; Johnson and 

others, 2019) or used modeling approaches to evaluate the 

probability of movement or passability (Cote and others, 

2009; Norman and others, 2009; Anderson and others, 2012). 

Despite prevailing evidence in the literature of direct and 

indirect effects of culverts on fish communities, few studies 

have addressed the effects of culvert length, in contrast to 

culvert type or other physical attributes (for example, perched 

or hanging culvert). Using an information-theoretic approach 

based on fish movement in both natural and experimental 

streams, Bouska and Paukert (2010) found that the best model 

to account for the greatest proportion of two species of Great 

Plains cyprinids (Cyprinella lutrensis and Notropis topeka) 

that moved upstream from culverts included decreased culvert 

slope and length, perching, and increased culvert width. Using 

a similar logistic regression approach, Briggs and Galarowicz 

(2013) found that of several variables examined, culvert 

length had the greatest effect on the proportion of the cyprinid 

Semotilus atromaculatus found upstream from culverts in an 

agricultural setting in Michigan.

Like our study, Wellman and others (2000) were unable 

to detect any differences in fish diversity, abundance, or 

richness between streams with culverts and those with 

bridges. Nor could they detect differences between upstream 

and downstream reaches. It is possible that our sample sizes 

were too small and that samples were collected over too 

short of a duration to detect any meaningful differences, 

or the culverts in our study simply might not affect the fish 

communities. Moreover, the dominance of relatively few 

common, widespread species and the low abundance of many 

fish species that were found at a few sites did not allow for 

sufficient numbers to discriminate between sites or reaches, 

with the only notable difference being that communities were 

closely associated with physiographic province.

Unlike fish, some localized effects to the 

macroinvertebrate communities were evident adjacent to the 

culverts, but results were inconsistent and often confounding. 

As demonstrated by the preceding results, there was 

considerable variability. No consistent patterns were observed 

in macroinvertebrate community composition in relation 

to proximity to the culvert, among or between any of the 

categories (fig. 18A–C).

Many studies have assessed how land-use changes 

affect stream biota (Cuffney and others, 2010; Brown and 

others, 2012; Waite and others, 2014). Booth and Jackson 

(1997), Coles and others (2004), and Gregory and Calhoun 

(2007) reported that stream biota responded to low levels of 

development. For the current study, the land-cover criteria 

were initially constrained to minimize natural variation among 

study sites. Under these conditions, suitable study sites were 

unavailable; therefore, land-cover criteria were relaxed to 

meet the study design goal of 20 sites. As a result, responses 

of the macroinvertebrate community to culvert effects may 

have been masked by differences in the amount of watershed 

development between study sites (Booth and Jackson, 1997).

Other culvert studies that were in smaller geographic 

areas with fewer sites that had similar geomorphic and 

habitat (including substrate) conditions reported that culverts 

affected macroinvertebrate communities (Khan and Colbo; 

2008; Peterson, 2010; Lawrence and others, 2014). In 

contrast, our study focused on collecting spatial replicates 

of “control-impact” sites over a large geographic area 

that spanned two physiographic provinces. Although the 

results were inconsistent and confounding, changes in the 

macroinvertebrate communities were detected near the culvert 

at a few sites in the Piedmont (both short and long culverts). 

Additional sampling and site-specific analysis could provide 

further information as to the abiotic variables contributing 

to the observed differences in macroinvertebrate community 

assemblage, yet such a site-specific analysis was beyond 

the scope of this investigation. Nonetheless, this study does 

provide foundational information that could be used to design 

future culvert studies in South Carolina.
Conclusions 41

Historical land-use practices and the channel alteration 

(straightening) that was prevalent with past culvert 

construction make drawing straightforward conclusions 

difficult. At many sites, we noted potentially confounding 

factors such as evidence of historical channel straightening, 

remnants of mill dams, or past beaver activity. The ability to 

link changes in channel morphology and habitat with culvert 

effects alone is confounded by these additional factors that 

likely led to some of the observed variability within and 

among sites. Nonetheless, the data indicate that sites in the 

Upper Coastal Plain showed a consistent geomorphologic 

response of channel incision downstream from culverts at five 

of the six sites; however, this geomorphic alteration was not 

necessarily associated with degraded biological conditions. 

At several sites, it was associated with more diverse habitat 

conditions (fig. 4) and a more diverse fish community (fig. 14).

Implications for Future Culvert Design and 

Mitigation

Although results from the present study are specific to 

box culverts and are based on a small sample size, several 

findings are consistent with previous research and are worth 

highlighting as considerations for future culvert design and 

mitigation. Streams in relatively undisturbed Piedmont and 

Upper Coastal Plain settings often have intact floodplains 

that allow frequent high flows (1- to 2-year RI) to exit the 

channel and spread out, thereby reducing energy and stresses 

applied to the streambed and banks. Flood attenuation is a 

critical function of stream ecosystems to maintain the balance 

of erosion and deposition, which influences the stability 

and productivity of aquatic habitats. In this regard, some 

States (for example, Minnesota and Texas) have studied and 

demonstrated the benefits of floodplain culverts in reducing 

flooding, channel erosion, sedimentation, and maintenance 

costs (Zytkovicz and Murtada, 2017). Analogous to the 

floodplain culvert is the staggered culvert design that has 

been researched in Texas (Cleveland and others, 2013). The 

staggered culvert approach uses a master culvert that handles 

bankfull and low flows in the main channel and additional 

culverts with inverts (culvert lip) at a higher elevation 

that only receive water when flow exits the main channel. 

This design reportedly helps reduce maintenance costs by 

reducing sediment accumulation and allowing a more natural 

sediment transport regime. Another approach that has been 

implemented in Ohio is the use of bankfull embedded culvert 

design (Tumeo and Pavlick, 2011). The rationale is similar 

to that of floodplain culverts in that the first step in design 

is to evaluate the size and characteristics of the natural 

channel and design a culvert that will accommodate similar 

flow. The primary focus is to prevent perching that leads 

to disconnected stream systems and to maintain consistent 

benthic habitat and ecological integrity. The use of floodplain 

culverts or staggered culverts may alleviate, or even reverse, 

incision downstream from culverts, as was observed in the 

Upper Coastal Plain in the present study. It is generally 

accepted that incision occurs when high-flow events are 

funneled through the culvert opening in a deeper, faster, more 

concentrated stream rather than the broad, shallow sheet flow 

that would have occurred prior to berm construction. Although 

these approaches may improve potential issues related to 

morphological adjustments, there is uncertainty regarding 

the biological response that may result from these alternate 

designs because no significant differences in community 

structure were observed in the current study.

Conclusions

The South Carolina Department of Transportation is 

required by the South Carolina Department of Health and 

Environmental Control and the U.S. Army Corps of Engineers 

to mitigate any perceived effects of culvert installation or 

replacement. A key factor in the level of mitigation is the 

length of the culvert. A long culvert would disrupt a longer 

section of natural stream but, if properly sized and installed, 

could have less overall effect on the stream channel stability 

and ecological integrity than a short culvert. In this analysis, 

geomorphic and biotic community structure were evaluated 

at sites with box culverts that varied by length. Although our 

sample size was small, the results did not suggest that culvert 

length influenced geomorphic conditions or community 

structure of fish or macroinvertebrates in the Piedmont region 

of South Carolina. Differences were noted in geomorphic 

conditions in the Upper Coastal Plain in the form of channel 

enlargement, primarily deepening, downstream from the 

culvert at five of the six sites. The prevalence of channel 

enlargement and the possible interaction with culvert length 

and type warrant further study. If this result is found to be 

common across culvert types (pipes, boxes, arches), other 

culvert design methods could be explored that may alleviate or 

reduce the effects.
42 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

References Cited

Abt, S.R., Ruff, J.F., and Doehring, F.K., 1985, Culvert 

slope effects on outlet scour: Journal of Hydraulic 

Engineering, v. 111, no. 10, p. 1363–1367. [Also 

available at https://doi.org/10.1061/(ASCE)0733-

9429(1985)111:10(1363).]

Anderson, G.B., Freeman, M.C., Freeman, B.J., Straight, C.A., 

Hagler, M.M., and Peterson, J.T., 2012, Dealing with 

uncertainty when assessing fish passage through culvert 

road crossings: Environmental Management, v. 50, no. 3, 

p. 462–477. [Also available at https://doi.org/10.1007/

s00267-012-9886-6.]

Benton, P.D., Ensign, W.E., and Freeman, B.J., 2008, The 

effect of road crossings on fish movements in small 

Etowah Basin streams: Southeastern Naturalist, v. 7, no. 2, 

p. 301–310. [Also available at https://doi.org/10.1656/1528-

7092(2008)7[301:TEORCO]2.0.CO;2.]

Birnie-Gauvin, K., Franklin, P., Wilkes, M., and Aarestrup, K., 

2019, Moving beyond fitting fish into equations—

Progressing the fish passage debate in the Anthropocene: 

Aquatic Conservation—Marine and Freshwater 

Ecosystems, v. 29, no. 7, p. 1095–1105, accessed May 5, 

2019, at https://doi.org/10.1002/aqc.2946.

Booth, D.B., and Jackson, C.R., 1997, Urbanization 

of aquatic systems—Degradation thresholds, 

stormwater detection, and the limits of mitigation: 

Journal of the American Water Resources Association, 

v. 33, no. 5, p. 1–20, accessed June 4, 2019, at 

https://doi.org/10.1111/j.1752-1688.1997.tb04126.x.]

Bouska, W.W., Keane, T., and Paukert, C.P., 2010, 

The effects of road crossings on prairie stream 

habitat and function: Journal of Freshwater 

Ecology, v. 25, no. 4, p. 499–506. [Also available at 

https://doi.org/10.1080/02705060.2010.9664398.]

Bouska, W.W., and Paukert, C.P., 2010, Road crossing 

designs and their impact on fish assemblages of Great 

Plains streams: Transactions of the American Fisheries 

Society, v. 139, no. 1, p. 214–222, accessed May 5, 2019, at 

https://doi.org/10.1577/T09-040.1.

Briggs, A.S., and Galarowicz, T.L., 2013, Fish passage 

through culverts in central Michigan warmwater 

streams: North American Journal of Fisheries 

Management, v. 33, no. 3, p. 652–664. [Also available at 

https://doi.org/10.1080/02755947.2013.788589.]

Brown, L.R., May, J.T., Rehn, A.C., Ode, P.R., Waite, I.R., 

and Kennen, J.G., 2012, Predicting biological condition 

in southern California streams: Landscape and Urban 

Planning, v. 108, no. 1, p. 17–27, accessed May 5, 2019, at 

https://doi.org/10.1016/j.landurbplan.2012.07.009.

Clarke, K.R., and Gorley, R.N., 2015, PRIMER v7—User 

manual/tutorial: Devon, United Kingdom, PRIMER-E 

Ltd., 296 p. [Also available at http://updates.primer-e.com/

primer7/manuals/User_manual_v7a.pdf.]

Cleveland, T.G., Strom, K.B., Barnes, W.J., and Dixon. J.V., 

2013, Hydraulic performance of staggered-barrel culverts 

for stream crossings: Federal Highway Administration 

report no. FHWA/TX–13/0–6549–1, prepared by Texas 

Tech University, report no. 0–6549–1, 123 p., accessed 

June 12, 2019, at https://www.depts.ttu.edu/techmrtweb/

reports/complete_reports/0-6549-1.pdf.

Cocchiglia, L., Purcell, P.J., and Kelly-Quinn, M., 2012, 

A critical review of the effects of motorway river-crossing 

construction on the aquatic environment: Freshwater 

Reviews, v. 5, no. 2, p. 141–168. [Also available at 

https://doi.org/10.1608/FRJ-5.2.489.]

Coles, J.F., Cuffney, T.F., McMahon, G., and Beaulieu, K.M., 

2004, The effects of urbanization on the biological, 

physical, and chemical characteristics of coastal 

New England streams: U.S. Geological Survey 

Professional Paper 1695, 58 p., accessed January 2019 at 

https://doi.org/10.3133/pp1695.

Cote, D., Kehler, D.G., Bourne, C., and Wiersma, Y.F., 

2009, A new measure of longitudinal connectivity 

for stream networks: Landscape Ecology, 

v. 24, no. 1, p. 101–113. [Also available at 

https://doi.org/10.1007/s10980-008-9283-y.]

Cuffney, T.F., Bilger, M.B., and Haigler, A.M., 2007, 

Ambiguous taxa—Effects on the characterization and 

interpretation of invertebrate assemblages: Journal of 

the North American Benthological Society, v. 26, no. 2, 

p. 286–307. [Also available at https://doi.org/10.1899/0887-

3593(2007)26[286:ATEOTC]2.0.CO;2.]

Cuffney, T.F., and Brightbill, R.A., 2011, User’s manual for the 

National Water-Quality Assessment Program Invertebrate 

Data Analysis System (IDAS) software, version 5: 

U.S. Geological Survey Techniques and Methods 7–C4, 

126 p. [Also available at https://doi.org/10.3133/tm7C4.]

Cuffney, T.F., Brightbill, R.A., May, J.T., and Waite, I.R., 

2010, Responses of benthic macroinvertebrates to 

environmental changes associated with urbanization 

in nine metropolitan areas: Ecological Applications, 

v. 20, no. 5, p. 1384–1401, [Also available at 

https://doi.org/10.1890/08-1311.1.]
References Cited 43

Doll, B.A., Dobbins, A.D., Spooner, J., Clinton, D.R., and 

Bidelspach, D.A., 2003, Hydraulic geometry relationships 

for rural North Carolina Coastal Plain streams: Raleigh, 

N.C., North Carolina Division of Water Quality, prepared 

by North Carolina Stream Restoration Institute, 319 Grant 

Project No. EW20011, 11 p., accessed March 13, 2019, 

at https://www.bae.ncsu.edu/extension/srp/technicalresources/.

Doll, B.A., Wise-Frederick, D.E., Buckner, C.M., 

Wilkerson, S.D., Harman, W.A., Smith, R.E., and 

Spooner, J., 2002, Hydraulic geometry relationships 

for urban streams throughout the Piedmont of North 

Carolina: Journal of the American Water Resources 

Association, v. 38, no. 3, p. 641–651. [Also available at 

https://doi.org/10.1111/j.1752-1688.2002.tb00986.x.]

Downes, B.J., Lake, P.S., and Schreiber, E.S.G., 

1993, Spatial variation in the distribution of stream 

invertebrates—Implications of patchiness for models 

of community organization: Freshwater Biology, 

v. 30, no. 1, p. 119–132, accessed May 2019 at 

https://doi.org/10.1111/j.1365-2427.1993.tb00793.x.

Dunne, T., and Leopold, L.B., 1978, Water in environmental 

planning: San Francisco, W.H. Freeman, 818 p.

Evans, N.T., Riley, C.W., and Lamberti, G.A., 2015, 

Culvert replacement enhances connectivity of stream 

fish communities in a Michigan drainage network: 

Transactions of the American Fisheries Society, 

v. 144, no. 5, p. 967–976, accessed June 2019 at 

https://doi.org/10.1080/00028487.2015.1054519.

Favaro, C., Moore, J.W., Reynolds, J.D., and Beakes, M.P., 

2014, Potential loss and rehabilitation of stream longitudinal 

connectivity—Fish populations in urban streams with 

culverts: Canadian Journal of Fisheries and Aquatic 

Sciences, v. 71, no. 12, p. 1805–1816. [Also available at 

https://doi.org/10.1139/cjfas-2014-0199.]

Fitzpatrick, F.A., Waite, I.R., D’Arconte, P.J., Meador, M.R., 

Maupin, M.A., and Gurtz, M.E., 1998, Revised methods for 

characterizing stream habitat in the National Water-Quality 

Assessment Program: U.S. Geological Survey 

Water-Resources Investigations Report 98–4052, 67 p. 

[Also available at https://doi.org/10.3133/wri984052.]

Gibson, R.J., Haedrich, R.L., and Wernerheim, C.M., 2005, 

Loss of fish habitat as a consequence of inappropriately 

constructed stream crossings: Fisheries, v. 30, no. 1, 

p. 10–17, accessed May 2019 at https://doi.org/10.1577/

1548-8446(2005)30[10:LOFHAA]2.0.CO;2.

Gieswein, A., Hering, D., and Lorenz, A.W., 2019, 

Development and validation of a macroinvertebrate-based 

biomonitoring tool to assess fine sediment impact 

in small mountain streams: Science of the Total 

Environment, v. 652, p. 1290–1301, accessed May 2019 at 

https://doi.org/10.1016/j.scitotenv.2018.10.180.

Gregory, M.B., and Calhoun, D.L., 2007, Physical, chemical, 

and biological responses of streams to increasing watershed 

urbanization in the Piedmont ecoregion of Georgia 

and Alabama, 2003: U.S. Geological Survey Scientific 

Investigations Report 2006–5101–B, 104 p., accessed 

January 2019 at https://pubs.usgs.gov/sir/2006/5101B.

Gregory, S.V., Boyer, K.L., and Gurnell, A.M., eds., 2003, 

The ecology and management of wood in world rivers: 

American Fisheries Society Symposium 37, 444 p.

Harman, W.A., 2000, Finding bankfull stage in North 

Carolina streams: North Carolina State University 

Extension web page, accessed December 2, 2017, at 

https://content.ces.ncsu.edu/finding-bankfull-stage-in-northcarolina-streams.

Harman, W.A., Jennings, G.D., Patterson, J.M., Clinton, D.R., 

Slate, L.O., Jessup, A.G., Everhart, J.R., and Smith, R.E., 

1999, Bankfull hydraulic geometry relationships for North 

Carolina streams, in Olsen, D.S., and Potyondy, J.P., eds., 

Wildland hydrology—AWRA symposium proceedings, 

Bozeman, Mont., June 30–July 2, 1999: Herndon, Va., 

American Water Resources Association, p. 401–408.

Hotchkiss, R.H., and Frei, C.M., 2007, Design for fish passage 

at roadway-stream crossings—Synthesis report: McLean, 

Va., Federal Highway Administration report no. FHWA–

HI–07–033, variously paged.

Hothorn, T., Hornik, K., van de Wiel, M.A., and Zeileis, A., 

2008, Implementing a class of permutation tests—

The coin package: Journal of Statistical Software, 

v. 28, no. 8, p. 1–23, accessed December 2018 at 

https://doi.org/10.18637/jss.v028.i08.

Hubert, W.A., and Fabrizio, M.C., 2007, Relative abundance 

and catch per unit effort, chap. 7 of Guy, C.S., and 

Brown, M.L., eds., Analysis and interpretation of freshwater 

fisheries data: Bethesda, Md., American Fisheries Society, 

p. 279–325.

Huser, D., 2009, Local effects of culverts on habitat features 

and fish assemblages in Blue Ridge streams: Chattanooga, 

Tenn., University of Tennessee at Chattanooga, unpub. 

M.S. thesis, 62 p.
44 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

Jackson, C.R., Martin, J.K., Leigh, D.S., and West, L.T., 

2005, A southeastern Piedmont watershed sediment 

budget—Evidence for a multi-millennial agricultural 

legacy: Journal of Soil and Water Conservation, 

v. 60, no. 6, p. 298–310. [Also available at 

http://www.jswconline.org/content/60/6/298.abstract.]

Johnson, K., Wait, L.E., Monk, S.K., Rader, R., 

Hotchkiss, R.H., and Belk, M.C., 2019, Effects of 

substrate on movement patterns and behavior of stream 

fish through culverts—An experimental approach: 

Sustainability, v. 11, no. 2, 13 p., accessed June 2019 at 

https://doi.org/10.3390/su11020470.

Jones, J.I., Murphy, J.F., Collins, A.L., Sear, D.A., Naden, P.S., 

and Armitage, P.D., 2012, The impact of fine sediment on 

macro-invertebrates: River Research and Applications, 

v. 28, no. 8, p. 1055–1071, accessed May 2019 at 

https://doi.org/10.1002/rra.1516.

Kaller, M.D., and Hartman, K.J., 2004, Evidence of a 

threshold level of fine sediment accumulation for altering 

benthic macroinvertebrate communities: Hydrobiologia, 

v. 518, no. 1–3, p. 95–104, accessed May 2019 at 

https://doi.org/10.1023/B:HYDR.0000025059.82197.35.

Kemp, P.S., and Williams, J.G., 2008, Response of migrating 

Chinook salmon (Oncorhynchus tshawytscha) smolts to 

in-stream structure associated with culverts: River Research 

and Applications, v. 24, no. 5, p. 571–579. [Also available 

at https://doi.org/10.1002/rra.1140.]

Khan, B., and Colbo, M.H., 2008, The impact of physical 

disturbance on stream communities—Lessons from road 

culverts: Hydrobiologia, v. 600, no. 1, p. 229–235, accessed 

August 2016 at https://doi.org/10.1007/s10750-007-9236-5.

Kim, J., 2015. How to choose the level of significance—A 

pedagogical note: Munich Personal RePEc Archive 

paper no. 66373, 13 p., accessed August 30, 2019, at 

https://mpra.ub.uni-muenchen.de/66373/.

Kish, L., 1959, Some statistical problems in research 

design: American Sociological Review, v. 24, 

no. 3, p. 328–338, accessed August 30, 2019, at 

https://doi.org/10.2307/2089381.

Kondolf, G.M., and Wolman, M.G., 1993, The sizes 

of salmonid spawning gravels: Water Resources 

Research, v. 29, no. 7, p. 2275–2285. [Also available at 

https://doi.org/10.1029/93WR00402.]

Lassettre, N.S., and Kondolf, G.M., 2012, Large woody debris 

in urban stream channels—Redefining the problem: River 

Research and Applications, v. 28, no. 9, p. 1477–1487, 

accessed May 2019 at https://doi.org/10.1002/rra.1538.

Lawrence, J.E., Cover, M.R., May, C.L., and Resh, V.H., 

2014, Replacement of culvert styles has minimal 

impact on benthic macroinvertebrates in forested, 

mountainous streams of Northern California: 

Limnologica, v. 47, p. 7–20, accessed May 2019 at 

https://doi.org/10.1016/j.limno.2014.02.002.

Lenat, D.R., 1993, A biotic index for the southeastern United 

States—Derivation and list of tolerance values, with criteria 

for assigning water-quality ratings: Journal of the North 

American Benthological Society, v. 12, no. 3, p. 279–290, 

accessed March 2019 at https://doi.org/10.2307/1467463.

MacPherson, L.M., Sullivan, M.G., Foote, A.L., and 

Stevens, C.E., 2012, Effects of culverts on stream 

fish assemblages in the Alberta foothills: North 

American Journal of Fisheries Management, 

v. 32, no. 3, p. 480–490, accessed June 2019 at 

https://doi.org/10.1080/02755947.2012.686004.

McDonald, J.M., Starkey, E.N., Gregory, M.B., and Riley, J., 

2018, Wadeable stream reach-scale field data collection—

Version 1.0: Athens, Ga., National Park Service, Southeast 

Coast Network Standard Operating Procedure NPS/SECN/

SORP 1.2.16, 26 p.

Merrill, M.A., 2005, The effects of culverts and bridges on 

stream geomorphology: Raleigh, N.C., North Carolina State 

University, unpub. M.S. thesis, 153 p.

Merrill, M.A., and Gregory, J., 2004, The effects of culverts 

and bridges on stream geomorphology, chap. 1 of

Levine, J.F., Eads, C.B., Cope, W.G., Humphries, L.F., 

Bringolf, R.B., Lazaro, P.R., Shea, D., Vander Pluym, J., 

Eggleston, D., Merril, M.A., Gregory, J., and Bogan, A.E., 

A comparison of the impacts of culverts versus bridges 

on stream habitat and aquatic fauna: Federal Highway 

Administration report no. FHWA/NC/2006–15, prepared 

by North Carolina State University and North Carolina 

Museum of Natural Sciences, 420 p.

Norman, J.R., Hagler, M.M., Freeman, M.C., and 

Freeman, B.J., 2009, Application of a multistate model 

to estimate culvert effects on movement of small 

fishes: Transactions of the American Fisheries Society, 

v. 138, no. 4, p. 826–838, accessed March 2019 at 

https://doi.org/10.1577/T08-156.1.

Ott, R.L., and Longnecker, M., 2001, An introduction to 

statistical methods and data analysis (5th ed.): Pacific 

Grove, Calif., Duxbury Press, 1,152 p.

Pennington, W., 2016, Standard operating procedures 

for processing, identification, and enumeration of 

invertebrate samples: Cookeville, Tenn., Pennington and 

Associates, Inc., 24 p.
References Cited 45

Peterson, T., 2010, The effect of road culverts on the benthic 

macroinvertebrate community in wadeable lotic ecosystems: 

PSU [Portland State University] McNair Scholars Online 

Journal, v. 4, no. 1, article no. 8, 23 p., accessed June 2016 

at https://doi.org/10.15760/mcnair.2010.52.

R Core Team, 2017, R—A language and environment 

for statistical computing, version 3.4.3. R Foundation 

for Statistical Computing software release, accessed 

December 2018, at https://www.R-project.org/.

Richardson, E.V., and Richardson, J.R., 1999, Determining 

contraction scour, in Richardson, E.V., and Lagasse, P.F., 

eds., Stream stability and scour at highway bridges—Water 

resources engineering—Compendium of stream stability 

and scour papers presented at conferences sponsored by 

the Water Resources Engineering (Hydraulics) Division 

of the American Society of Civil Engineers: Reston, Va., 

American Society of Civil Engineers, p. 483–491.

Riley, J.W., and Walsh, S.J., 2019, Stream habitat and 

geomorphic characteristics above and below culverts at 

selected sites in South Carolina (2017): U.S. Geological 

Survey data release, https://doi.org/10.5066/P9VD9AYY.

Schlosser, I.J., 1982, Fish community structure and function 

along two habitat gradients in a headwater stream: 

Ecological Monographs, v. 52, no. 4, p. 395–414, accessed 

July 9, 2019, at https://doi.org/10.2307/2937352.

Schumm, S.A., Harvey, M.D., and Watson, C.C., 1984, Incised 

Channels—Morphology, Dynamics and Control: Littleton, 

Colo., Water Resources Publications, 200 p. 

Scott, M., Rose, L., Marion, C.A., Kubach, K.M., 

Thomason, C., and Price, J., 2009, The South Carolina 

Stream Assessment standard operating procedures: 

Columbia, S.C., South Carolina Department of Natural 

Resources, 49 p.

Simon, A., 1989, A model of channel response in 

disturbed alluvial channels: Earth Surface Processes 

and Landforms, v. 14, no. 1, p. 11–26. [Also available at 

https://doi.org/10.1002/esp.3290140103.]

Simon, A., and Rinaldi, M., 2006, Disturbance, stream 

incision, and channel evolution—The roles of 

excess transport capacity and boundary materials 

in controlling channel response: Geomorphology, 

v. 79, nos. 3–4, p. 361–383, accessed June 3, 2019, at 

https://doi.org/10.1016/j.geomorph.2006.06.037.

Smokorowski, K.E., and Randall, R.G., 2017, Cautions 

on using the Before-After-Control-Impact design in 

environmental effects monitoring programs: Facets, 

v. 2, p. 212–232, accessed December 12, 2018, at 

https://doi.org/10.1139/facets-2016-0058.

South Carolina Department of Health and Environmental 

Control, 2017, Standard operating and quality control 

procedures for macroinvertebrate sampling: Columbia, S.C. 

South Carolina Department of Health and Environmental 

Control, Technical Report No. 0914–17, 19 p.

Swezey, C.S., Fitzwater, B.A., Whittecar, G.R., Mahan, S.A., 

Garrity, C.P., Gonzalez, W.B.A., and Dobbs, K.M., 2016, 

The Carolina Sandhills—Quaternary eolian sand sheets 

and dunes along the updip margin of the Atlantic Coastal 

Plain province, southeastern United States: Quaternary 

Research, v. 86, no. 3, p. 271–286, accessed May 2, 2019, at 

https://doi.org/10.1016/j.yqres.2016.08.007.

Trimble, S.W., 1974, Man-induced soil erosion on the southern 

Piedmont, 1700–1970: Ankeny, Iowa, Soil Conservation 

Society of America, 180 p.

Trimble, S.W., 1977, The fallacy of stream equilibrium in 

contemporary denudation studies: American Journal of 

Science, v. 277, no. 7, p. 876–887, accessed July 9, 2019, at 

https://doi.org/10.2475/ajs.277.7.876.

Tumeo, M.A., and Pavlick, J., 2011, Study of bankfull culvert 

design effectiveness: Columbus, Ohio, Ohio Department 

of Transportation, prepared by Cleveland State University 

under contract no. 134465, 58 p., accessed June 1, 

2019, at https://rosap.ntl.bts.gov/view/dot/20619/dot_

20619_DS1.pdf.

U.S. Army Corps of Engineers, 2010, Guidelines for 

preparing a compensatory mitigation plan: Charleston, 

S.C., U.S. Army Corps of Engineers, 18 p., 8 app., accessed 

September 30, 2017, at https://www.sac.usace.army.mil/

Portals/43/docs/regulatory/Guidelines_for_Preparing_a_

Compensatory_Mitigation_Planf.pdf.

U.S. Environmental Protection Agency, 2013, Level III 

ecoregions of the continental United States: Corvallis, 

Oreg., U.S. Environmental Protection Agency, 1 sheet, scale 

1:7,500,000, accessed May 2, 2019, at https://www.epa.gov/

eco-research/level-iii-and-iv-ecoregions-continentalunited-states.

U.S. Geological Survey, 2014, NLCD 2011 land 

cover conterminous United States: U.S. Geological 

Survey dataset.

U.S. Geological Survey, 2016, National Hydrography 

Dataset (NHD) best resolution for 20160905 State or 

Territory shapefile model version 2.2.1: U.S. Geological 

Survey dataset.

U.S. Geological Survey, 2017, 1 arc-second digital elevation 

models (DEMs)—USGS National Map 3DEP downloadable 

data collection: U.S. Geological Survey dataset.
46 Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities

U.S. Geological Survey, 2019, BioData—aquatic 

bioassessment data for the Nation : U.S. Geological 

Survey database, accessed April 2018 at 

https://doi.org/10.5066/F77W698B.

Voli, M.T., Wegmann, K.W., Bohnenstiehl, D.R., Leithold, E., 

Osburn, C.L., and Polyakov, V., 2013, Fingerprinting the 

sources of suspended sediment delivery to a large municipal 

drinking water reservoir—Falls Lake, Neuse River, 

North Carolina, USA: Journal of Soils and Sediments, 

v. 13, no. 10, p. 1692–1707, accessed July 2019 at 

https://doi.org/10.1007/s11368-013-0758-3.

Waite, I.R., Kennen, J.G., May, J.T., Brown, L.R., 

Cuffney, T.F., Jones, K.A., and Orlando, J.L., 2014, Stream 

macroinvertebrate response models for bioassessment 

metrics—Addressing the issue of spatial scale: PLoS One, 

v. 9, no. 3, article no. e90944, 21 p., accessed May 2019 at 

https://doi.org/10.1371/journal.pone.0090944.

Walter, R.C., and Merritts, D.J., 2008, Natural streams 

and the legacy of water-powered mills: Science, 

v. 319, no. 5861, p. 299–304, accessed June 3, 2019, at 

https://doi.org/10.1126/science.1151716.

Warren, M.L., Jr., and Pardew, M.G., 1998, Road crossings as 

barriers to small-stream fish movement: Transactions of the 

American Fisheries Society, v. 127, no. 4, p. 637–644. [Also 

available at https://doi.org/10.1577/1548-8659(1998)127<0

637:RCABTS>2.0.CO;2.]

Waters, T.F., ed., 1995, Sediment in streams—Sources, 

biological effects, and control: Bethesda, Md., American 

Fisheries Society Monograph 7, 251 p.

Wellman, J.C., Combs, D.L., and Cook, S.B., 2000, 

Long-term impacts of bridge and culvert construction 

or replacement on fish communities and sediment 

characteristics of streams: Journal of Freshwater Ecology, 

v. 15, no. 3, p. 317–328, accessed July 12, 2019, at 

https://doi.org/10.1080/02705060.2000.9663750.

Wohl, E., 2017, Bridging the gaps—An overview 

of wood across time and space in diverse rivers: 

Geomorphology, v. 279, p. 3–26. [Also available at 

https://doi.org/10.1016/j.geomorph.2016.04.014.]

Wolman, M.G., 1954, A method for sampling coarse river-bed 

material: Eos, Transactions, American Geophysical 

Union, v. 35, no. 6, p. 951–956. [Also available at 

https://doi.org/10.1029/TR035i006p00951.]

Wolman, M.G., and Leopold, L.B., 1957, River flood plains—

Some observations on their formation: U.S. Geological 

Survey Professional Paper 282–C, 23 p. [Also available at 

https://doi.org/10.3133/pp282C.]

Wood, P.J., and Armitage, P.D., 1997, Biological effects of 

fine sediment in the lotic environment: Environmental 

Management, v. 21, no. 2, p. 203–217, accessed May 2019 

at https://doi.org/10.1007/s002679900019.

Zytkovicz, K., and Murtada, S., 2017, Floodplain culvert 

fact sheet: Saint Paul, Minn., Minnesota Department 

of Natural Resources, 2 p., accessed April 25, 2019, at 

https://files.dnr.state.mn.us/eco/streamhab/geomorphology/

floodplain-culvert-factsheet.pdf.
Appendix 1. Macroinvertebrate Metrics and Sample Classifications 47

Appendix 1. Macroinvertebrate Metrics and Sample Classifications

This appendix contains two tables related to the 

macroinvertebrate sample results. Specifically, table 1.1

defines metrics that were calculated and evaluated for use in 

data analysis for the report. Table 1.2 contains the values for 

each metric described in table 1.1, for each sample.

Reference Cited

Lenat, D.R., 1993, A biotic index for the southeastern United 

States—Derivation and list of tolerance values, with criteria 

for assigning water-quality ratings: Journal of the North 

American Benthological Society, v. 12, no. 3, p. 279–290, 

accessed March 2019 at https://doi.org/10.2307/1467463.

Table 1.1. Macroinvertebrate metric descriptions.

[EPA, U.S. Environmental Protection Agency; EPT, Ephemeroptera, Plecoptera, Tricoptera (mayflies, stoneflies, caddisflies)]

Metric Description

Abund Total number of organisms in the sample

Rich Total richness (number of nonambiguous taxa)

AbundTOL Abundance-weighted EPA tolerance value for sample

EPTR Richness composed of EPT

EPTp Percent of total abundance composed of EPT

EPT_CHp Ratio of EPT to Chironomidae midge abundance

CHp Percent of total abundance composed of Chironomidae midges

pPR_abund Percent of total abundance composed of predators

pOM_abund Percent of total abundance composed of omnivores

pCG_abund Percent of total abundance composed of collector gatherers

pFC_abund Percent of total abundance composed of filtering collectors

pSC_abund Percent of total abundance composed of scrapers

pSH_abund Percent of total abundance composed of shredders

Dom1 Percentage of total abundance represented by the most abundant taxa

Margalef Margalef’s Diversity

Pielou’s evenness Pielou’s evenness

ShannonDiv Shannon’s diversity

SimpsonDiv Simpson’s diversity
Table 1.2. Macroinvertebrate metrics for samples collected at selected culvert sites in South Carolina, 2016–18. [Metric descriptions are provided in table 1.1. Classes were defined by Lenat (1993) and are based on AbundTOL values] Sample identifica- tion Abund Rich Abund- TOL Class EPTR EPTp EPT_ CHp CHp pPR_ abund pOM_ abund pCG_ abund pFC_ abund pSC_ abund pSH_ abund Dom1 Margalef Pie

eve

Piedmont long culverts centercr1 3,881 18 7.35 Fair 0 0 0 20.87 4.77 1.56 46.02 11.17 31.72 4.77 35.74 2.06 0

centercr2 5,760 24 6.98 Fair 1 0.56 0.0002 61.11 11.39 5.06 34.81 22.78 24.68 1.27 21.11 2.66 0centercr3 1,103 35 7.05 Fair 2 4.35 0.0070 56.21 15.82 7.96 25.25 17.49 27.11 6.39 18.68 4.85 0centercr4 3,837 27 6.86 Fair 2 1.67 0.0009 49.44 16.08 2.07 30.09 37.07 14.70 0 18.35 3.15 0enoree1 1,722 39 3.36 Excellent 13 62.02 0.2061 17.48 13.29 0.80 67.93 7.74 6.28 3.94 25.38 5.10 0enoree2 834 41 5.34 Good 10 26.86 0.0574 56.12 32.10 2.05 35.17 9.59 7.42 13.68 9.59 5.95 0enoree3 4,205 38 4.06 Excellent 8 48.11 0.0354 32.37 13.04 2.75 54.77 19.16 2.06 8.23 33.48 4.43 0enoree4 1,210 30 4.72 Excellent 8 20.66 0.0249 68.60 46.67 2.86 20.95 11.43 3.81 14.29 15.70 4.09 0millersfk1 1,720 19 8.29 Poor 0 0 0 25.29 11.79 8.23 64.52 4.78 0 10.68 29.36 2.42 0millersfk2 2,893 18 7.53 Fair 0 0 0 23.92 12.87 8.47 55.23 4.24 0 19.19 23.89 2.13 0millersfk3 10,859 18 7.73 Fair 0 0 0 17.40 11.37 2.28 63.63 2.28 0 20.44 54.33 1.83 0millersfk4 3,040 24 6.76 Fair 1 0.66 0.0005 42.11 7.23 0 42.17 3.61 0 46.99 25.00 2.87 0t2rockcr1 1,496 42 6.05 Good- fair 7 21.39 0.0270 52.94 20.77 3.80 20.72 33.94 0 20.77 11.76 5.61 0t2rockcr2 668 39 6.02 Good- fair 7 11.38 0.0327 52.10 7.25 15.94 17.39 30.43 0 28.99 13.17 5.84 0t2rockcr3 796 39 6.16 Good- fair 6 29.65 0.0720 51.76 6.98 5.67 36.76 16.86 0 33.73 23.62 5.69 0t2rockcr4 1,608 40 6.18 Good- fair 8 7.96 0.0070 71.14 10.62 10.62 19.80 19.94 4.59 34.43 17.91 5.28 0t2taylorcr1 3,104 22 6.16 Good- fair 3 3.61 0.0035 33.51 15.67 10.07 43.28 19.40 0 11.57 49.48 2.61 0t2taylorcr2 1,515 20 7.87 Poor 0 0 0 49.24 12.17 3.37 50.19 27.34 0 6.93 28.84 2.59 0t2taylorcr3 5,344 18 6.68 Fair 2 4.79 0.0028 31.74 12.75 0.67 41.61 26.85 0.67 17.45 59.88 1.98 0t2taylorcr4 6,440 14 6.73 Fair 1 1.24 0.0010 19.25 21.11 2.13 49.47 15.78 0 11.51 73.91 1.48 0taylorcr1 7,383 22 5.94 Good 3 2.32 0.0016 20.24 22.94 17.43 16.51 25.69 14.68 2.75 33.52 2.36 0taylorcr2 2,736 24 5.88 Good 3 7.02 0.0084 30.41 12.75 8.28 25.64 16.28 34.33 2.71 51.46 2.91 0taylorcr3 1,879 24 6.04 Goodfair 5 3.99 0.0059 35.82 22.13 5.74 40.98 20.49 9.02 1.64 37.47 3.05 0taylorcr4 1,022 30 6.32 Goodfair 3 4.11 0.0073 55.19 15.32 12.90 32.26 25.81 8.87 4.84 22.41 4.18 0
Table 1.2. Macroinvertebrate metrics for samples collected at selected culvert sites in South Carolina, 2016–18.—Continued[Metric descriptions are provided in table 1.1. Classes were defined by Lenat (1993) and are based on AbundTOL values]

Sample 

identification Abund Rich Abund- TOL Class EPTR EPTp EPT_ CHp CHp pPR_ abund pOM_ abund pCG_ abund pFC_ abund pSC_ abund pSH_ abund Dom1 Margalef Pie

eve

Piedmont long culverts—Continued

timscrk1 308 33 5.53 Good 4 4.22 0.0227 60.39 13.29 1.27 39.87 12.03 0.63 32.91 12.01 5.58 0timscrk2 606 33 5.37 Good 2 2.48 0.0073 56.27 7.26 2.89 33.83 7.26 0.74 48.02 21.78 4.99 0timscrk3 1,288 35 5.37 Good 4 3.11 0.0038 63.98 14.79 6.34 48.59 23.94 2.82 3.52 22.98 4.75 0timscrk4 578 40 5.39 Good 2 2.77 0.0093 51.38 15.52 2.59 52.59 16.38 0.86 12.07 9.34 6.13 0

Piedmont short culverts

beaverdam1 542 31 5.79 Good 4 2.95 0.0063 86.53 8.74 2.14 34.17 15.92 1.17 37.86 33.95 4.77 0beaverdam2 330 44 6.40 Good- fair 5 10.91 0.0718 46.06 21.33 13.33 38.00 22.67 0 4.67 10.91 7.41 0beaverdam3 870 34 6.11 Good- fair 4 12.64 0.0269 54.02 11.54 14.10 42.31 14.74 4.49 12.82 13.22 4.88 0beaverdam4 210 38 6.80 Fair 4 6.67 0.0623 50.95 10.66 19.29 29.95 19.29 1.02 19.80 16.67 6.92 0bluebr1 1,900 30 6.36 Goodfair 3 12.63 0.0100 66.32 8.88 15.38 7.69 60.95 5.33 1.78 49.47 3.84 0bluebr2 1,240 39 6.20 Goodfair 4 18.06 0.0443 32.90 21.11 11.11 32.22 24.44 8.89 2.22 26.45 5.33 0bluebr3 6,208 23 5.91 Good 4 3.61 0.0019 31.44 5.71 8.57 31.43 50.00 2.86 1.43 60.31 2.52 0bluebr4 1,940 27 7.47 Fair 2 9.79 0.0090 56.19 17.61 10.23 37.50 19.89 6.25 8.52 30.93 3.43 0drycrk1 2,541 37 5.90 Good 5 21.25 0.0202 41.36 13.76 2.31 39.66 16.67 14.37 13.23 13.42 4.59 0drycrk2 712 22 6.70 Fair 1 1.12 0.0088 17.98 20.51 0 25.64 12.82 38.46 2.56 21.35 3.20 0drycrk3 2,826 26 6.96 Fair 1 3.26 0.0059 19.64 23.49 1.58 17.23 9.35 42.09 1.58 26.04 3.15 0drycrk4 900 28 6.90 Fair 3 4.44 0.0143 34.44 15.87 0 23.81 30.16 28.57 1.59 12.22 3.97 0indiancr1 5,417 25 6.33 Goodfair 3 3.93 0.0010 71.42 9.00 2.12 5.83 72.46 8.47 2.12 64.98 2.79 0indiancr2 7,246 27 6.82 Fair 1 1.09 0.0006 24.43 4.34 1.45 39.11 25.38 26.09 3.63 20.66 2.93 0indiancr3 4,321 19 7.13 Fair 1 3.70 0.0029 29.62 1.60 6.44 43.54 17.75 30.66 0 17.29 2.15 0indiancr4 4,455 23 6.32 Goodfair 4 7.79 0.0044 39.51 3.12 4.35 41.58 35.44 3.73 11.78 23.34 2.62 0lilhogskin1 2,658 32 6.36 Good- fair 2 3.20 0.0015 79.23 10.30 0.64 41.29 23.28 10.30 14.20 12.87 3.93 0
Table 1.2. Macroinvertebrate metrics for samples collected at selected culvert sites in South Carolina, 2016–18.—Continued [Metric descriptions are provided in table 1.1. Classes were defined by Lenat (1993) and are based on AbundTOL values] Sample identifica- tion Abund Rich Abund- TOL Class EPTR EPTp EPT_ CHp CHp pPR_ abund pOM_ abund pCG_ abund pFC_ abund pSC_ abund pSH_ abund Dom1 Margalef Pie

eve

Piedmont short culverts—Continued lilhog- skin2 3,504 31 6.64 Good- fair 3 1.83 0.0007 76.71 10.31 1.55 25.77 24.74 21.13 15.46 15.07 3.68 0

lilhog- skin3 1,005 28 5.06 Good 5 4.18 0.0053 77.91 5.50 0.57 24.40 27.49 0.57 41.47 19.10 3.91 0lilhog- skin4 1,760 39 6.14 Good- fair 5 4.55 0.0036 72.73 15.97 1.39 27.08 30.56 7.64 17.36 12.50 5.08 0trib2alli- son1 1,416 33 3.76 Excellent 6 11.86 0.0141 59.32 22.67 4.00 41.35 11.99 3.31 16.68 23.73 4.41 0trib2alli- son2 1,637 38 4.03 Excellent 10 16.43 0.0156 64.57 32.23 4.13 45.45 4.13 2.48 11.57 38.42 5.00 0trib2alli- son3 1,630 41 6.00 Good- fair 3 4.91 0.0040 74.85 15.20 0 60.00 14.40 0 10.40 20.86 5.41 0trib2alli- son4 1,280 38 5.44 Good 4 6.25 0.0063 78.13 8.84 2.76 65.75 6.08 2.21 14.36 21.25 5.17 0trib-2payne1 1,740 43 5.03 Excellent 9 20.34 0.0239 49.02 12.66 28.48 35.44 21.52 1.27 0.63 7.99 5.63 0trib-2payne2 1,224 37 6.24 Good- fair 4 3.27 0.0035 76.47 7.14 18.75 38.39 25.00 1.79 8.93 16.34 5.06 0trib-2payne3 2,272 33 5.21 Excellent 4 23.94 0.0238 44.37 5.59 35.20 34.08 23.46 0.56 1.12 17.61 4.14 0trib-2payne4 1,980 39 6.42 Good- fair 8 16.16 0.0207 39.39 12.64 25.82 24.18 31.32 1.10 4.95 30.81 5.01 0

Upper Coastal Plain short culverts bigpine- tree1 1,863 30 5.69 Good 5 20.77 0.0230 48.58 25.89 0.87 33.94 37.49 0 1.81 12.88 3.85 0

bigpine- tree2 1,540 40 5.61 Good 7 11.04 0.0107 66.88 31.71 5.69 22.76 37.40 0.81 1.63 16.23 5.31 0bigpine- tree3 2,849 24 5.25 Good 3 4.39 0.0070 21.94 11.97 0 5.36 76.72 2.64 3.31 66.76 2.89 0bigpinetree4 2,157 34 4.78 Excellent 4 20.40 0.0149 63.56 31.49 1.39 39.97 21.46 0.70 4.99 12.98 4.30 0cowbr1 2,416 37 5.10 Excellent 6 9.27 0.0055 70.20 25.44 3.51 32.46 29.82 7.02 1.75 19.87 4.62 0cowbr2 1,910 33 5.03 Excellent 7 15.71 0.0143 57.59 22.58 10.32 23.87 27.10 14.19 1.94 17.28 4.24 0
Table 1.2. Macroinvertebrate metrics for samples collected at selected culvert sites in South Carolina, 2016–18.—Continued[Metric descriptions are provided in table 1.1. Classes were defined by Lenat (1993) and are based on AbundTOL values]

Sample 

identification Abund Rich Abund- TOL Class EPTR EPTp EPT_ CHp CHp pPR_ abund pOM_ abund pCG_ abund pFC_ abund pSC_ abund pSH_ abund Dom1 Margalef Pie

eve

Upper Coastal Plain short culverts—Continued

cowbr3 3,380 29 4.59 Excellent 4 7.69 0.0029 78.11 31.54 4.62 32.31 23.85 4.62 2.31 16.57 3.45 0cowbr4 1,392 30 4.85 Excellent 5 11.49 0.0138 59.77 17.29 6.77 33.08 33.83 8.27 0.75 22.41 4.01 0sadler1 4,484 31 4.55 Excellent 5 6.53 0.0018 80.95 4.60 7.78 31.18 16.22 1.29 38.92 35.68 3.57 0sadler2 2,101 26 5.06 Excellent 4 9.14 0.0063 69.54 1.38 7.49 27.93 25.12 7.49 30.59 26.18 3.27 0sadler3 5,150 35 5.12 Excellent 4 4.66 0.0011 81.32 3.81 8.12 27.55 25.91 6.50 28.10 26.93 3.98 0sadler4 3,460 41 5.18 Excellent 6 8.09 0.0037 63.01 7.97 13.77 16.67 34.78 7.25 18.84 13.87 4.91 0tinker1 1,264 37 5.09 Excellent 7 29.11 0.0758 30.38 5.43 3.26 71.20 17.39 2.17 0.54 10.13 5.04 0tinker2 1,124 41 5.29 Good 10 14.23 0.0262 48.31 8.97 2.97 59.48 16.08 12.5 0 22.51 5.69 0tinker3 1,820 43 5.50 Good 8 37.91 0.0665 31.32 8.42 5.26 50.53 27.37 4.21 4.21 13.19 5.60 0tinker4 1,144 45 5.40 Good 6 13.29 0.0198 58.74 8.20 2.98 20.88 54.49 13.44 0 8.39 6.25 0trib4hole1 1,990 24 6.67 Goodfair 1 2.51 0.0015 82.41 4.82 1.20 37.35 9.64 0 46.99 60.80 3.03 0trib4hole2 4,586 21 7.21 Fair 0 0 0 79.28 5.02 1.04 48.48 16.19 21.21 8.05 45.20 2.37 0trib4hole3 1,980 23 6.80 Fair 0 0 0 82.83 3.28 1.64 59.02 29.51 1.64 3.28 43.94 2.90 0trib4hole4 10,023 25 5.76 Good 3 2.13 0.0003 67.55 0 0 45.95 37.84 0 16.22 25.01 2.61 0trueblue1 640 28 5.65 Good 4 3.75 0.0105 55.63 7.80 14.18 25.53 41.13 9.93 0.71 23.75 4.18 0trueblue2 3,820 30 5.82 Good 1 1.05 0.0003 80.10 14.69 16.95 12.43 46.33 8.47 1.13 33.51 3.52 0trueblue3 3,480 18 5.87 Good 0 0 0 86.21 8.82 17.65 28.24 44.71 0.59 0 29.89 2.08 0trueblue4 1,800 25 5.48 Good 2 1.67 0.0015 60 6.06 6.67 15.15 56.97 13.94 1.21 36.11 3.20 0

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20205021

For more information concerning the research in this report, contact

Director, South Atlantic Water Science Center U.S. Geological Survey 

720 Gracern Road

Stephenson Center, Suite 129 Columbia, SC 29210 https://www.usgs.gov/centers/sa-water

Publishing support provided by the U.S. Geological Survey 

Science Publishing Network, Reston and Sacramento 

Publishing Service Centers
Riley and others—Effects of Box Culverts on Stream Habitat, Channel Morphology, and Fish and Macroinvertebrate Communities—SIR 2020–5021

ISSN 2328-0328 (online)

https://doi.org/10.3133/sir20205021