Assessment of Habitat and Streamflow 

Requirements For Habitat Protection, 

Usquepaug–Queen River, Rhode Island, 

1999–2000

By DAVID S. ARMSTRONG and GENE W. PARKER

Open-File Report 02-438

In cooperation with the

RHODE ISLAND DEPARTMENT OF 

ENVIRONMENTAL MANAGEMENT

Northborough, Massachusetts

2003
For additional information write to:

Chief, Massachusetts-Rhode Island District

U.S. Geological Survey

10 Bearfoot Road

Northborough, Massachusetts 01532

or visit our Web site at

http://ma.water.usgs.gov

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does 

not imply endorsement by the U.S. Government.

Copies of this report can be purchased from:

U.S. Geological Survey

Branch of Information Services

Box 25286

Denver, CO 80225-0286

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director
Contents III

CONTENTS

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

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

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

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

Previous Studies.......................................................................................................................................... 6

Acknowledgments....................................................................................................................................... 6

Study Methods...................................................................................................................................................... 6

Habitat Assessment ..................................................................................................................................... 6

Stream-Temperature Assessment................................................................................................................ 7

Fish-Community Assessment...................................................................................................................... 8

Determination of Streamflow Requirements for Habitat Protection........................................................... 9

Methods Based on Streamflow Records ............................................................................................ 9

Indicators of Hydrologic Alteration and Range of Variability Approach ................................ 9

Tennant Method........................................................................................................................ 10

New England Aquatic-Base-Flow Method............................................................................... 10

Methods Based on Physical and Hydraulic Characteristics............................................................... 11

Wetted-Perimeter Method......................................................................................................... 12

R2Cross Method ....................................................................................................................... 14

Characterization of Stream Habitat, Temperature, and Fish Communities ......................................................... 15

Habitat Assessments.................................................................................................................................... 16

Usquepaug River near Usquepaug (Site U3), South Kingstown ....................................................... 16

Usquepaug River near Laurel Lane (Site U2), South Kingstown...................................................... 16

Usquepaug River at Route 138 (Site U1), South Kingstown............................................................. 18

Queen River near Kingston Road (Site Q8), Exeter .......................................................................... 20

Queen River at Liberty Road (Site Q7), Exeter ................................................................................. 20

Queen River near Dawley Road (Site Q6), Exeter ............................................................................ 21

Queen River at Dawley Road (Site Q5), Exeter ................................................................................ 22

Queen River near New School Land Road (Site Q4), Exeter............................................................ 23

Queen River at William Reynolds Road (Site Q3), Exeter................................................................ 24

Queen River near William Reynolds Road (Site Q2), Exeter............................................................ 25

Locke Brook at Mail Road (Site L1), Exeter ..................................................................................... 26

Fisherville Brook at Liberty Church Road (Site F2), Exeter ............................................................. 27

Fisherville Brook near Pardon Joslin Road (Site F1), Exeter............................................................ 28

Summary of Habitat Variability with Flow ....................................................................................... 28

Stream Temperature.................................................................................................................................... 30

Fish-Community Assessment...................................................................................................................... 34
IV Contents

Streamflow Requirements for Habitat Protection ................................................................................................ 37

Indicators of Hydrologic Alteration and Range of Variability Approach................................................... 38

Tennant Method .......................................................................................................................................... 43

New England Aquatic-Base-Flow Method ................................................................................................. 45

Wetted-Perimeter Method........................................................................................................................... 45

R2Cross Method.......................................................................................................................................... 47

Comparison of Streamflow Requirements and Methods ..................................................................................... 48

Suggestions for Further Study.............................................................................................................................. 52

Summary and Conclusions................................................................................................................................... 53

References Cited .................................................................................................................................................. 55

Appendix 1 Study-site Descriptions and Documentation of Input and Calibration Data for 

HEC-RAS and WinXSPro Models ...................................................................................................................... 61

1. Site U2, Usquepaug River near Laurel Lane, Richmond/South Kingstown, Rhode Island.................... 61

2. Site U1, Usquepaug River at Route 138, Richmond/South Kingstown, Rhode Island .......................... 62

3. Site Q5, Queen River near Dawley Road, Exeter, Rhode Island............................................................ 64

4. Site Q3, Queen River near William Reynolds Road, Exeter, Rhode Island ........................................... 66

5. Site L1, Locke Brook at Mail Road, Exeter, Rhode Island..................................................................... 67

6. Site F2, Fisherville Brook at Liberty Church Road, Exeter, Rhode Island............................................. 68

7. Site F1, Fisherville Brook near Pardon Joslin Road, Exeter, Rhode Island............................................ 69
Figures V

FIGURES

Figure 1. Map showing location of towns, drainage network, impoundments, gaging stations, and

habitat-assessment sites, Usquepaug–Queen River Basin, Rhode Island.......................................... 3

Figure 2. Hydrograph showing daily mean discharge, water years 1999–2000, and median of daily 

mean discharge for the period of record for the Usquepaug River at Usquepaug gaging 

station (01117420) ............................................................................................................................. 5

Figure 3. Diagram showing example of (A) a stream-channel cross section and graph showing 

(B) the relation between wetted perimeter and discharge.................................................................. 13

Figure 4. Photographs showing habitat features on the Usquepaug River, near Usquepaug (Site U3) 

South Kingstown: (A) bend pool and exposed sandbar, upstream view, and (B) submerged 

aquatic vegetation and overhanging vegetation, downstream view................................................... 18

Figure 5. Photographs showing habitat features on the Usquepaug River near Laurel Lane (Site U2), 

South Kingstown: (A) riffle-and-run habitat, upstream view, and (B) woody debris, 

downstream view ............................................................................................................................... 18

Figure 6. Photographs showing habitat features on the Usquepaug River at Route 138 (Site U1), 

South Kingstown: (A) riffle habitat, downstream view, and (B) riffle habitat, upstream view......... 19

Figure 7. Photographs showing habitat features on the Queen River near Kingston Road (Site Q8), 

Exeter: (A) vegetated sand bars, upstream view, and (B) overhanging vegetation and deep 

pool, downstream view ...................................................................................................................... 20

Figure 8. Photographs showing habitat features on the Queen River at Liberty Road (Site Q7), 

Exeter: (A) vegetated sand bars, upstream view, and (B) shallow stream margins, 

downstream view ............................................................................................................................... 21

Figure 9. Photographs showing habitat features on the Queen River near Dawley Road (Site Q6), 

Exeter: (A) undercut trees, downstream view, and (B) submerged aquatic vegetation, 

downstream view ............................................................................................................................... 22

Figure 10. Photographs showing habitat features on the Queen River at Dawley Road (Site Q5), 

Exeter: (A) riffle, upstream view, and (B) left bank showing loss of stream margin habitat 

at low flows, downstream view ......................................................................................................... 23

Figure 11. Photographs showing habitat features on the Queen River near School Land Road 

(Site Q4), Exeter: (A) shallow water, upstream view, and (B) loss of habitat at stream 

margins, upstream view ..................................................................................................................... 24

Figure 12. Photographs showing habitat features on the Queen River at William Reynolds Road 

(Site Q3), Exeter: (A) riffle with rectangular cross section during low flow, downstream 

view, and (B) loss of stream-margin habitat, upstream view............................................................. 25

Figure 13. Photographs showing habitat features on the Queen River near William Reynolds Road 

(Site Q2), Exeter: (A) woody debris, upstream view, and (B) loss of stream-margin habitat ........... 26

Figure 14. Photographs showing habitat features on Locke Brook at Mail Road (Site L1), Exeter: 

(A) riffle, upstream view, and (B) riffle, downstream view............................................................... 27

Figure 15. Photographs showing habitat features on Fisherville Brook at Liberty Church Road 

(Site F2), Exeter: (A) riffle, downstream view, and (B) riffle, downstream view ............................. 28
VI Figures

Figure 16. Photographs showing habitat features on Fisherville Brook near Pardon Joslin Road, 

(Site F1), Exeter: (A) woody debris, downstream view, and (B) run, upstream view ....................... 29

Figure 17. Graphs showing stream temperature in the Usquepaug–Queen River, June to September 

2000: (A) Queen River at Route 102, Exeter, (B) Queen River at William Reynolds 

Road, Exeter, (C) Fisherville Brook at Liberty Church Road, Exeter, (D) Queen River at 

Dawley Road, Exeter, (E) Queen River at Liberty Road, Exeter, (F) Locke Brook at Mail 

Road, Exeter, (G) Usquepaug River at Route 138, South Kingstown, and (H) Usquepaug 

River at Route 2, South Kingstown ................................................................................................... 31

Figure 18. Pie charts showing fish species habitat-use classifications for the Usquepaug–Queen River: 

(A) mainstem sites, 1998–2000, and (B) tributary sites, 1998–2000................................................. 36

Figure 19. Pie charts showing target fish communities for the: (A) Quinebaug River, Massachusetts, and 

(B) Ipswich River, Massachusetts...................................................................................................... 37

Figure 20. Boxplot showing distribution of monthly mean flow, Usquepaug River near Usquepaug, 

gaging station (01117420) ................................................................................................................. 38

Figure 21. Boxplot showing distribution of monthly mean flow for August for 11 gaging stations in 

southern New England....................................................................................................................... 46

Figure 22. Boxplot showing distribution of median Wetted-Perimeter and R2Cross streamflow 

requirements for seven riffle sites on the Usquepaug–Queen River and the average 

distribution of the monthly mean flow during summer for the Beaver River (01117468), 

Branch River (01111500), and Wood River (01117800) gaging stations, Rhode Island, 

and the Indian Head River (01105730), Massachusetts..................................................................... 49

Figure 23. Graph showing median Wetted-Perimeter and R2Cross streamflow requirements, and daily

mean streamflows at the Usquepaug River gaging station (01117420), between May and 

September during dry, normal, and wet years: (A) dry years, 1994 and 1999, (B) normal 

years, 1978 and 1988, and (C) wet years, 1996 and 2000 ................................................................. 51

Figure 24. Graph showing flow-duration curve for the Usquepaug River near Usquepaug, gaging 

station (01117420), 1958–2000 ......................................................................................................... 52
Tables VII

TABLES

Table 1. Range of Variability Approach: flow statistics for characterization of hydrologic variation............ 10

Table 2. Relations between aquatic-habitat condition and mean annual flow described by the 

Tennant method for small streams..................................................................................................... 11

Table 3. Seasonal New England Aquatic-Base-Flow default streamflow requirements ................................. 11

Table 4. R2Cross criteria for hydraulic parameters for protection of aquatic habitat ..................................... 14

Table 5. Location and description of stations for habitat assessments, determination of streamflow 

requirements, temperature dataloggers, and fish sampling in the Usquepaug–Queen River 

Basin, Rhode Island ........................................................................................................................... 17

Table 6. Number of each species and percent of total number of fish collected in the mainstem and 

tributaries of the Usquepaug–Queen River, by the U.S. Environmental Protection Agency 

New England Regional Laboratory in 2000 and the Rhode Island Division of Fish and 

Wildlife in 1998 ................................................................................................................................. 35

Table 7. Scientific names and habitat-use classifications of fish in the Usquepaug–Queen River 

Basin .................................................................................................................................................. 36

Table 8. Hydrologic data for the 1976 to 2000 period for the gaging station Usquepaug River near

Usquepaug (01117420)...................................................................................................................... 39

Table 9. Hydrologic data for the 1976 to 2000 period for the gaging station Beaver River near

Usquepaug (01117468)...................................................................................................................... 41

Table 10. Hydrologic data for the 1976 to 2000 period for the gaging station Wood River near 

Arcadia (01117800) ........................................................................................................................... 42

Table 11. Summer streamflow requirements determined by the Tennant method for the gaging station 

Usquepaug River near Usquepaug (01117420) ................................................................................. 44

Table 12. Streamflow requirements determined by the Tennant Method for 16 gaging stations in 

southern New England....................................................................................................................... 44

Table 13. Streamflow requirements computed by Wetted-Perimeter and R2Cross methods for seven 

riffle study sites, Usquepaug–Queen River ....................................................................................... 47

Table 1.1. Hydraulic criteria simulated by WinXSPRO for the Usquepaug River near Laurel Lane, 

Richmond/South Kingstown.............................................................................................................. 62

Table 1.2. Hydraulic criteria simulated by WinXSPRO for the Usquepaug River at Route 138, 

upstream section, Richmond/South Kingstown................................................................................. 63

Table 1.3. Hydraulic criteria simulated by WinXSPRO for the Usquepaug River at Route 138, 

downstream section, Richmond/South Kingstown............................................................................ 64

Table 1.4. Hydraulic criteria simulated by HEC-RAS for the Queen River near Dawley Road, Exeter ........... 65

Table 1.5. Hydraulic criteria simulated by WinXSPRO for the Queen River near William Reynolds

Road, Exeter....................................................................................................................................... 66

Table 1.6. Hydraulic criteria simulated by WinXSPRO for Locke Brook at Mail Road, Exeter....................... 67

Table 1.7. Hydraulic criteria simulated by WinXSPRO for Fisherville Brook at Liberty Church 

Road, Exeter....................................................................................................................................... 68

Table 1.8. Hydraulic criteria simulated by WinXSPRO for Fisherville Brook near Pardon Joslin Road, 

Exeter ................................................................................................................................................. 69
VIII Conversion Factors, Vertical Datum, and Acronyms 

CONVERSION FACTORS, VERTICAL DATUM, AND 

ACRONYMS

CONVERSION FACTORS

Temperature in degrees Celsius (°C) can be converted to degrees Fahrenheit (°F) as follows:

°F = (1.8 x °C) + 32

Temperature in degrees Fahrenheit (°F) can be converted to degrees Celsius (°C) as follows:

°C = (°F – 32) ÷ 1.8

VERTICAL DATUM

Sea Level: In this report, “sea level” refers to the National Geodetic Vertical Datum of 1929 (NGVD 

of 1929)—a geodetic datum derived from a general adjustment of the first-order level nets of the 

United States and Canada, formerly called Sea Level Datum of 1929.

Multiply By To obtain

cubic feet per second (ft3/s) 0.02832 cubic meter per second

cubic feet per second per square mile (ft3/s/mi2) 0.01093 cubic meter per second per square kilometer

foot (ft) 0.3048 meter

foot per second (ft/s) 0.3048 meter per second

inch (in.) 2.54 centimeter

inch (in.) 25.4 millimeter

mile (mi) 1.609 kilometer

square feet (ft2) 0.0929 square meter

square mile (mi2) 259 hectare

ACRONYMS

ABF Aquatic Base Flow

FD Fluvial Dependent

FS Fluvial Specialist

IHA Indicators of Hydrologic 

Alteration

HEC-RAS [U.S. Army Corps of 

Engineers] Hydrologic 

Engineering Center—River 

Analysis System

HSPF Hydrologic Simulation 

Program–Fortran

MG Macrohabitat Generalist

RBP [U.S. Environmental 

Protection Agency] Rapid 

Bioassessment Protocol

RIDEM Rhode Island Department of 

Environmental Management

RIDFW Rhode Island [Department of 

Environmental Management] 

Division of Fish and Wildlife

RVA Range of Variability Approach

TNC The Nature Conservancy

TU Trout Unlimited

USFWS U.S. Fish and Wildlife Service

USEPA U.S. Environmental Protection 

Agency

USGS U.S. Geological Survey

WPWA Wood-Pawcatuck Watershed 

Association

WUSG [Pawcatuck Watershed Partnership] 

Water Use Stakeholders Group
Abstract 1

Assessment of Habitat and Streamflow 

Requirements for Habitat Protection, 

Usquepaug–Queen River, Rhode Island, 

1999–2000

By David S. Armstrong and Gene W. Parker

ABSTRACT

The relations among stream habitat and 

hydrologic conditions were investigated in the 

Usquepaug–Queen River Basin in southern Rhode 

Island. Habitats were assessed at 13 sites on the 

mainstem and tributaries from July 1999 to 

September 2000. Channel types are predominantly 

low-gradient glides, pools, and runs that have a 

sand and gravel streambed and a forest or shrub 

riparian zone. Along the stream margins, 

overhanging brush, undercut banks supported by 

roots, and downed trees create cover; within the 

channel, submerged aquatic vegetation and woody 

debris create cover. These habitat features 

decrease in quality and availability with declining 

streamflows, and features along stream margins 

generally become unavailable once streamflows 

drop to the point at which water recedes from the 

stream banks. Riffles are less common, but were 

identified as critical habitat areas because they are 

among the first to exhibit habitat losses or become 

unavailable during low-flow periods.

Stream-temperature data were collected 

at eight sites during summer 2000 to indicate the 

suitability of those reaches for cold-water fish 

communities. Data indicate stream temperatures 

provide suitable habitat for cold-water species in 

the Fisherville and Locke Brook tributaries and 

in the mainstem Queen River downstream of 

the confluence with Fisherville Brook. Stream 

temperatures in the Usquepaug River downstream 

from Glen Rock Reservoir are about 6°F warmer 

than in the Queen River upstream from the 

impoundment. These warmer temperatures may 

make habitat in the Usquepaug River marginal 

for cold-water species. 

Fish-community composition was 

determined from samples collected at seven sites 

on tributaries and at three sites on the mainstem 

Usquepaug–Queen River. Classification of the fish 

into habitat-use groups and comparison to target 

fish communities developed for the Quinebaug 

and Ipswich Rivers indicated that the sampled 

reaches of the Usquepaug–Queen River contained 

most of the riverine fish species that would have 

been expected to occur in this area. 

Streamflow records from the gaging station 

Usquepaug River near Usquepaug were used to 

(1) determine streamflow requirements for habitat 

protection by use of the Tennant method, and 

(2) define a flow regime that mimics the river's 

natural flow regime by use of the Range of 

Variability Approach. The Tennant streamflow 

requirement, defined as 30 percent of the mean 

annual flow, was 0.64 cubic feet per second per 

square mile (ft3/s/mi2). This requirement should 

be considered an initial estimate because flows 

measured at the Usquepaug River gaging station 

are reduced by water withdrawals upstream from 

the gage. The streamflow requirements may need 

to be revised once a watershed-scale precipitationrunoff model of the Usquepaug River is complete 

and a simulation of streamflows without water 

withdrawals has been determined.
2 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Streamflow requirements for habitat 

protection were also determined at seven riffle 

sites by use of the Wetted-Perimeter and R2Cross 

methods. Two of these sites were on the mainstem 

Usquepaug River, one was on the mainstem 

Queen River, and four were on tributaries and 

the headwaters of the Queen River. Median 

streamflow requirements for habitat protection 

for these sites were 0.41 (ft3/s)/mi2, determined by 

the Wetted-Perimeter method and 0.72 ft3/s/mi2, 

determined by the R2Cross method. 

INTRODUCTION

During the summer, when streamflows are 

naturally low and the demand for water is high, water 

users in the Pawcatuck River Basin in southwestern 

Rhode Island and southeastern Connecticut are in 

competition for a limited supply of water. Federal, 

State, and local agencies as well as private citizen 

groups and other water-use organizations are 

concerned that reduced streamflows created by water 

withdrawals could cause a loss of aquatic habitat and 

reductions in habitat quality needed to support the 

biological integrity of the Pawcatuck River system. 

In recognition that the quantity and quality of 

water may not be sufficient to meet all needs and 

interests, and that solutions to competing water needs 

will require cooperation among many stakeholders, 

the Pawcatuck Watershed Partnership Water Use 

Stakeholders Group (WUSG) was formed in 1997. 

The group consists of representatives from State and 

Federal environmental agencies, municipal water 

suppliers, universities, nonprofit environmental 

advocacy and conservation organizations, farmers, and 

other individuals. The WUSG determined that a 

subbasin of the Pawcatuck River Basin, the 

Usquepaug–Queen River Basin, could serve as a pilot 

area in which to focus data collection and modeling 

efforts. The U.S. Geological Survey (USGS) in 

cooperation with the Rhode Island Department of 

Environmental Management (RIDEM), began a habitat 

assessment of the Usquepaug–Queen River in June 

1999. The goals of this effort were to understand 

aquatic-habitat availability under various streamflow 

conditions and to determine the streamflows needed for 

habitat protection in the Usquepaug–Queen River. An 

additional goal was to coordinate habitat assessments 

with an ongoing watershed-modeling project for the 

Usquepaug–Queen River Basin that is being developed 

by the USGS in cooperation with the Rhode Island 

Water Resources Board. Once the effects of water 

withdrawals on streamflows are modeled, the 

combined USGS efforts will provide a better 

understanding of the effects of water withdrawals on 

stream habitat.

Purpose and Scope

This report describes the stream habitats, 

summer water temperatures, and fish communities of 

the Usquepaug–Queen River, and determines 

streamflows necessary to maintain aquatic habitat in 

the Usquepaug–Queen River for the summer period. 

The study area includes the mainstem and tributaries of 

the Usquepaug–Queen River upstream from Route 2 in 

South Kingstown. The report describes results of 

assessments of stream habitat, fish communities, and 

stream temperature conducted in 1999 and 2000 for the 

Usquepaug–Queen River and its tributaries, and 

compares streamflow requirements determined by 

means of the Tennant, Wetted-Perimeter, and R2Cross 

methods to flow-management targets developed by 

means of the Range of Variability Approach (RVA). 

Streamflow requirements were determined at seven 

riffle sites: three on the mainstem Usquepaug–Queen 

River, and four on the Fisherville Brook and Locke 

Brook tributaries, and in the headwaters of the Queen 

River. 

Description of the Study Area

The Usquepaug–Queen River, a tributary to the 

Pawcatuck River, is entirely within southern Rhode 

Island (fig. 1). The Usquepaug–Queen River Basin is 

bounded by the Beaver River Basin to the west, 

the Big River and Hunt Basins to the north, the 

Cocumcussoc, Annaquatucket, and Mattatuxet 

Coastal Basins to the East, and the Chipuxet Basin 

to the south. The study area includes all of the 

Queen River Basin and that portion of the Usquepaug 

River Basin between the river's origin at the outfall of 

Glen Rock Reservoir, in Usquepaug, RI, and the 

USGS streamflow-gaging station on the Usquepaug 

River upstream from Route 2 (station 01117420). 
Introduction 3

EAST GREENWICH WEST GREENWICH

NORTH

KINGSTOWN

EXETER

RICHMOND

SOUTH KINGSTOWN

01117468

011173545

01117370

01117410

01117350

01117420

Q1

F1

F2 Q2

Q4

Q5

Q6

Q7

L1

Q8

U1

U2

U3

Q3

41o30'

41o

37'30"

71o

37'30" 71o

32'30"

1 2 MILES

0 1 2 KILOMETERS

0 Base from U.S. Geological Survey

Hope Valley, R.I., 1:24000, photorevision as of 1970,

Kingston, R.I., 1:24000, photorevision as of 1970,

Slocum, R.I., 1:24000, photorevision as of 1970

Polyconic projection. 1927 North American datum

Usquepau g River

Glen Rock Brook

She mr a n Brook

Locke Brook

Sodom B roo k

Fisherville Brook

Queen River Queens Fort Brook

Rive r

Queen

Beaver Rive r

Chickasheen Brook

Chipuxet River

Church Rd.

Liberty 

William 

2

138

102

Reynolds Rd.

Glen Rock Reservoir 

0 10 MILES

0 10 KILOMETERS

RHODE ISLAND

SOUND

41o45'

71o

45' 71o30'

41o

30'

42o

00'

Rhode Island

STUDY

AREA

Mail Rd.

Liberty Rd.

EXPLANATION

BASIN BOUNDARY

SUBBASIN BOUNDARY

GAGING STATION

AND NUMBER

HABITAT-ASSESSMENT

SITE AND NUMBER

Q1

01117370

Figure 1. Location of towns, drainage network, impoundments, gaging stations, and habitat-assessment sites, Usquepaug–Queen 

River Basin, Rhode Island.
4 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

The gaging station is 1.2 mi upstream of the 

Chickasheen River and about 2.1 mi upstream from 

the confluence of the Usquepaug River with the 

Pawcatuck River. The study area is approximately 

10 mi long and about 5 mi wide, and encompasses a 

36 mi2 area. Most of the study area is in Washington 

County, with a small area of the northern part of the 

basin in Kent County. The study area comprises parts 

of six towns, including most of the town of Exeter, and 

parts of the towns of Richmond, West Greenwich, East 

Greenwich, North Kingstown, and South Kingstown. 

The drainage basin of the Usquepaug–Queen 

River is within the coastal lowland physiographic 

province of New England (Denny, 1982). The basin is 

characterized by low, rolling hills separated by flat 

valleys. Maximum relief in the river basin is about 

460 ft. The Usquepaug–Queen River Valley trends 

northeast-southwest. Tributary valleys generally lie 

between northwest-trending ridges on the northwest 

side of the valley, and southeast-trending ridges on the 

southeast side of the valley. The ridges are formed by 

bedrock overlain by as much as 60 ft of glacial till 

(Dickerman and others, 1997). Glacial till generally is 

a compact, nonsorted mixture of sand, silt, clay, and 

stones. The low permeability of till and steep slopes in 

till areas reduce the amount of infiltration and groundwater storage and cause rapid runoff of surface water 

during storms. A bedrock valley beneath the 

Usquepaug–Queen River and Fisherville–Sodom 

tributary is filled with glacial stratified deposits 

consisting of up to 122 ft of coarse-grained deposits of 

sand and gravel, and fine-grained deposits of very fine 

sand, silt, and clay (Dickerman and others, 1997). Sand 

and gravel deposits form the major aquifers in the 

basin, and ground-water discharge from these aquifers 

to the streams maintains base flow between 

precipitation events. Tributary streams that drain areas 

of sand and gravel deposits, such as those along the 

mainstem Queen River and Fisherville Brook, tend to 

have higher base flow than streams draining areas of 

till, such as the headwaters of the Queen River.

Based on meteorological data from 1961–90 

from Kingston, RI, the mean annual temperature in the 

Usquepaug–Queen Basin is 49.3°F. Deep ground-water 

temperatures in the region are about the same 

temperature as the mean annual temperature (Lapham, 

1989). The minimum monthly-mean temperature is 

27.7°F in January, and the maximum monthly-mean 

temperature is 70.5°F in July. Annual precipitation in 

southern Rhode Island averages approximately 48 in., 

and is distributed rather uniformly throughout the year 

(Johnston, 1986). The minimum monthly precipitation 

is about 3.3 in. in July, and the maximum monthly 

precipitation is about 5.3 in. in November. Average 

monthly precipitation in the remaining 10 months 

ranges between 3.7 and 4.6 in. Annual snowfall 

averages approximately 20 in. Average annual runoff is 

about 28 in. and is highest from December through 

May and lowest from June through November.

The USGS operates two permanent streamgaging stations in the study area (fig. 1). The upstream 

gage on the Queen River at Liberty Road at Liberty 

(station number 01117370) has a drainage area of 

19.1 mi2, and has been in operation since 1998. The 

downstream gage on the Usquepaug River near 

Usquepaug (station number 01117420) has a drainage 

area of 36.1 mi2, and has been in continual operation 

since 1974 (Socolow and others, 1999). The USGS has 

also operated two additional stream gaging stations 

(station numbers 011173545 and 01117410) on the 

Queen and Usquepaug Rivers on a temporary basis to 

collect hydrologic data for use in a watershed model 

(Socolow and others, 2001). A ground-water 

investigation of the basin (Dickerman and others, 1997) 

showed that the surface-water and ground-water 

divides do not coincide for part of the Queens Fort 

Brook subbasin and that the subsurface drainage area to 

the Usquepaug gaging station is about 33 mi2. The 

surface drainage area of 36.1 mi2 is used throughout 

this report to normalize flows by drainage area. The 

mean annual discharge at the Usquepaug gaging station 

is 76.8 ft3/s. Discharge at these sites, however, is 

affected by water withdrawals upstream of the gaging 

stations.

 Streamflows in the Usquepaug–Queen River are 

typically lowest in August and September. For the 

1974–99 period, the medians of monthly mean flows 

for August and September at the Usquepaug gaging 

station (01117420) were about 28.4 and 22.3 ft3/s, 

respectively. The daily mean discharge for water years 

1999 and 2000 and the range of daily flows for the 

period of record are shown in fig. 2. Stream discharges 

were low during 1999, the first year of this study, 

because of drought conditions. Annual high water 

typically occurs between Feburary and April, though 

peak floods also occur in August or September because 

of hurricanes. Flooding is infrequent in the basin
Introduction 5

because of the large number of ponds and reservoirs, 

extensive wetlands, highly permeable soils, and low 

stream gradients (Johnston, 1986). 

There are two large and a number of small 

impoundments in the Usquepaug–Queen River Basin. 

The farthest downstream of these, Glen Rock 

Reservoir, impounds the Queen River at Usquepaug, 

RI. A dam and mill have existed at or near this site 

since colonial times. The present dam is about 10 ft 

high and impounds water upstream for about a mile. 

Flows from the impoundment spill over a low-head 

dam and down a small canal near a gristmill. The 

second large impoundment, in the headwaters of Locke 

Brook, is formed by a 20-ft tall earthen dam. A smalldiameter (< 6 in.) pipe at the base of the dam provides a 

constant flow to Locke Brook. Several small dams and 

ponds are located on Fisherville, Sodom, Locke, and 

Glen Rock Brooks, and in the Queen River headwaters.

The Usquepaug–Queen River Basin is 

characterized by rural land use. Approximately 90 to 

95 percent of the basin is forested (Dickerman and 

others, 1997). The remainder of the basin is wetland, 

agricultural (primarily turf farming with some areas of 

row and vegetable crops, nurseries, and pasture), 

recreational (golf courses), commercial, and mediumto-low-density residential land. For most of its length, 

the Usquepaug–Queen River has a wide and relatively 

undisturbed riparian corridor; development, 

agriculture, or golf courses border the river in only a 

few locations. 

The Usquepaug–Queen River is an important 

natural resource for southern Rhode Island, and 

portions of the River are considered to be among the 

most pristine and least disturbed rivers in the State of 

Rhode Island (The Nature Conservancy, 2001). Several 

large parcels of land in the basin have been preserved 

by the Rhode Island Audubon Society, The Nature 

Conservancy, and by private landowners. The river 

provides unique habitat for a diversity of fauna, 

including a naturally-reproducing population of brook 

trout, one of the greatest concentrations of freshwater 

mussels in Rhode Island, and several dragonfly species 

1

10

100

1,000

ON D J FM AM J J A S ON D J F MAM J J A S

25th percentile of daily mean discharge for period of record

50th percentile of daily mean discharge for period of record

75th percentile of daily mean discharge for period of record

Daily mean discharge for water years 1999–2000 (October to September)

MONTHS

USQUEPAUG RIVER NEAR USQUEPAUG, RI 01117420

EXPLANATION

DISCHARGE, IN CUBIC FEET PER SECOND

MEAN DISCHARGES

WATER YEAR 1999 WATER YEAR 2000

Mean

50th

75th

25th

Figure 2. Daily mean discharge, water years 1999–2000, and median of daily mean discharge for the period of record for the 

Usquepaug River at Usquepaug gaging station (01117420), Rhode Island.
6 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

that rely upon cold-water riverine habitat and are listed 

by the Rhode Island Natural Heritage Program as 

species of concern (The Nature Conservancy, 2001; 

Pawcatuck Watershed Partnership, 1998). 

The Usquepaug–Queen River Basin is also an 

important source of water for agriculture, domestic 

water supply, and recreation. Currently, water is not 

imported or exported out of the basin. The predominant 

water withdrawals are surface-water withdrawals for 

agricultural and golf-course irrigation. Private water 

supplies are obtained from wells. There are no active 

centralized wastewater-treatment plants in the basin; a 

wastewater-treatment site at the site of the former Ladd 

School was shut down in 1995. Changes in land and 

water use related to development within the basin, the 

conversion of surface-water withdrawals to groundwater withdrawals, and a potential wastewatertreatment facility at the site of the former Ladd School 

could alter habitat, streamflow and water-quality 

conditions from those observed during this study. 

Previous Studies

Hydrologic and hydrogeologic information for 

the Basin is available from earlier studies that include 

part or all of the Usquepaug–Queen River Basin. 

Kliever (1995) provides information on ground-water 

levels and ground-water quality, surface-water flows, 

and surface-water quality in the Usquepaug River 

Basin. Dickerman and others (1997) describe the 

hydrogeology, water quality, and ground-water 

development alternatives in the Usquepaug–Queen 

Basin. 

Acknowledgments

The authors are grateful to the RIDEM Office of 

Water Resources, U.S. Environmental Protection 

Agency (USEPA), Pawcatuck Watershed Partnership 

WUSG, RIDEM Division of Fish and Wildlife 

(RIDFW), USEPA New England Regional Lab, Rhode 

Island Watershed Watch, and other public agencies, 

private organizations, and individuals who provided 

assistance, guidance and information during the study. 

Particular thanks are given to volunteers, including 

members of the Audubon Society of Rhode Island, 

Wood-Pawcatuck Watershed Association (WPWA), RI 

Trout Unlimited (TU), The Nature Conservancy 

(TNC), RIDEM, USEPA, and other individuals who 

provided field assistance with habitat assessments 

during this study. The cooperation of public and private 

landowners, who granted permission to access and 

sample the Usquepaug–Queen River and its tributaries, 

is appreciated. 

STUDY METHODS

This report provides (1) descriptions of stream 

habitat and habitat availability at different streamflows; 

(2) data showing stream temperatures collected at 

eight sites during summer 2000; (3) data collected 

between 1998 and 2000 showing fish community 

composition for mainstem and tributaries sites; 

(4) flow-management targets determined by means of 

the RVA and statistical summaries of the streamflow 

regimes of the Usquepaug–Queen River in comparison 

with streamflow regimes in nearby rivers in Rhode 

Island, Connecticut, and Massachusetts; and 

(5) determinations of streamflow requirements for 

habitat protection by use of the Tennant, Aquatic-BaseFlow (ABF), Wetted-Perimeter, and R2Cross methods. 

These descriptions and statistical summaries can be 

used by water managers to guide the determination of 

appropriate streamflows for the protection of stream 

habitat.

Habitat Assessment

A reconnaissance of the mainstem and selected 

tributaries of the Usquepaug–Queen River Basin was 

conducted to identify stream macrohabitats and to 

determine accessibility of potential sampling sites. The 

river can be subdivided into macrohabitats created by 

the combination of discrete channel geomorphic units 

with different types of valley geomorphology and 

riparian vegetation. Channel geomorphic units are 

homogeneous areas of a channel that differ in slope, 

water velocity, turbulence, flow-control structures, 

depth, and substrate characteristics from adjacent 

habitats. In general, riffles have steep gradients, fast 

flow velocities, shallow water depths, coarse-grained 

substrates (gravel, cobble, boulder), and turbulent 

surface flows that commonly contain small standing 

waves or white water. Runs have moderate gradients, 

moderate flow velocities and depths, a variety of 

substrates (sand and gravel), and somewhat turbulent 
Study Methods 7

but unbroken surfaces. Glides have low gradients and 

velocities, variable depths, fine-grained substrates (fine 

gravel, sand, organic detritus), and smooth surfaces. 

Pools have low gradients, moderate to deep water 

depths, fine-grained substrates (sand, silt, organic 

detritus), and slow velocities that are barely detectable 

or do not show at the surface. Impoundments are large 

pools behind artificial dams or beaver dams. Channel 

geomorphic units can be further subdivided into finer 

levels, such as log-enhanced or rootwad-, boulder-, 

or bedrock-formed lateral scour pools (Bain and 

Stevenson, 1999), but this level of classification is not 

used in this report. 

For this study the Usquepaug–Queen mainstem 

was defined to include the Usquepaug River from 

Route 2 to Glen Rock Reservoir and the Queen River 

from Glen Rock Reservoir to the mouth of Fisherville 

Brook. The portion of the Queen River upstream of 

the mouth of Fisherville Brook was considered to 

be a tributary to the mainstem Queen River. Habitatassessment study sites were selected to represent 

the different habitats available in the mainstem and 

tributaries, and to determine streamflow requirements 

for habitat protection. The most intensive datacollection efforts were focused on riffle reaches. Riffle 

reaches were targeted as critical areas for investigation 

of streamflow-habitat relations and for determination 

of streamflow requirements for habitat protection 

because of their sensitivity to low flows. During 

declining flows, riffles are among the first reaches to 

show habitat losses or to develop fish-passage 

problems. 

Multiple visits were made to study sites by 

volunteer and USGS teams to document habitat 

availability and quality at different flows. Most visits, 

however, were made in summer during periods of low 

flow. USEPA rapid-bioassessment protocols (RBP) 

(Barbour and others, 1999) were used to evaluate and 

document stream-habitat quality within each study 

reach. Volunteers were trained in 1999 and 2000 in the 

use of the RBP. Volunteers were provided with RBP 

manuals, data sheets, and digital cameras, along with 

habitat assessment, wading, and safety equipment. The 

WPWA and Rhode Island Watershed Watch assisted 

with the coordination of volunteer sampling activities 

and the storage of data and photos collected by the 

volunteers. Multiple habitat assessments were 

conducted at two study sites for the purposes of quality 

assurance.

The RBP scores stream-habitat quality by use of 

10 metrics that rate general categories of stream habitat 

for low-gradient streams: available cover, channel 

substrate, pool variability, sediment deposition, 

channel-flow status, channel alteration, channel 

sinuosity, bank stability, bank-vegetation protection, 

and riparian-zone width (Barbour and others, 1999). 

The RBP uses different metrics for high and low 

gradient reaches of streams. For high-gradient reaches, 

velocity/depth regime, embeddedness, and frequency 

of riffles are substituted for pool variability, channel 

substrate, and channel sinuosity, respectively (Barbour 

and others, 1999). Because of the moderate gradient 

of the Usquepaug–Queen and the predominance 

of coarse-sand and fine-gravel substrate, habitat 

assessments were completed for sites by use of RBP 

habitat-assessment field-data sheets that combined 

metrics for low-gradient and high-gradient streams. 

Each RBP metric is scored numerically between 0 and 

20; scores from 0 to 5 are considered poor habitat, 

scores from 6 to 10 indicate marginal habitat, scores 

from 11 to 15 indicate suboptimal habitat, and scores 

from 16 to 20 indicate optimal habitat. If each metric is 

rated with an optimum score of 20, the total score 

would be 200. Scores of 160 to 200 are considered 

optimal, 110 to 159 suboptimal, 60 to 109 marginal, 

and < 60 poor. The scores for three of the ten metrics 

(available cover, velocity/depth regime, and channelflow status) are dependent on the flow at the time the 

survey is made; therefore 30 percent of the total score 

is related to streamflow. Because a portion of the total 

score reflects features independent of flow, such as 

width of the riparian zone, the minimum scores are 

never zero, even if the river has no flow or is dry.

Stream-Temperature Assessment

Most methods for determining minimum 

streamflows for habitat protection are based on the 

assumption that summer low flow and habitat 

availability are limiting criteria for aquatic life. Other 

criteria affected by low flows, however, such as stream 

temperature and percent saturation of dissolved 

oxygen, can also be limiting factors that define suitable 

habitat. Water temperature is very important for the 

health and survival of native fish. Temperature regimes 

can influence migration, egg maturation, spawning, 
8 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

incubation success, growth, the ability to compete for 

food and avoid predators, and resistance to parasites, 

diseases and pollutants (Armour, 1991).

To assess the suitability of summer stream 

temperatures for cold-water fish species, streamtemperature data were collected at eight sites on the 

Usquepaug–Queen River during the summer of 2000. 

Temperature data were collected at half-hour intervals 

with Onset Computer StowAway TidbiT dataloggers. 

To protect the dataloggers and to reduce the effects of 

direct sunlight and ground-water discharge on recorded 

temperatures, dataloggers were installed at the bases of 

staff gages inside short lengths of perforated PVC pipe 

and slightly above the streambed. A quality-assurance 

test of the dataloggers was completed upon removal of 

the dataloggers from the river. The test, made with a 

National Institute of Standards and Technology 

certified thermometer, showed the temperatures to be 

accurate, and variability between dataloggers to be less 

than 1°F. 

For this report, the suitability of stream 

temperatures in the Usquepaug–Queen River for 

cold-water fish were indicated only through 

comparison of summer daily stream temperatures to 

critical and optimum ranges for brook trout (Elliot, 

1994), and by comparison of 7-day moving averages 

to temperature criteria for maximum weekly 

average temperatures (MWAT), and short-term maxima 

(STM) for juvenile and adult brook trout (Armour, 

1991). Temperature criteria for water-quality standards 

are generally applied for time-averaged characteristics 

of temperature such as the warmest 7-day average of 

daily maximum and mean temperature. Trout also 

respond to other temperature variables, however, 

such as maximum daily temperatures, mean daily 

temperatures, mean monthly temperatures, minimum 

diel fluctuations (difference between daily maximum 

and minimum temperatures), and cumulative thermal 

history (Sullivan and others, 2000). Because watertemperature tolerance varies between species and 

life stages, a complete assessment of the suitability 

of stream temperatures in the Usquepaug–Queen 

River for cold-water fish would include the streamtemperature requirements for different life-history 

stages (embryo/alevin, juvenile, adult) and activities 

(incubation, rearing, migration, spawning) for different 

cold-water species, and would also consider other 

important temperature-related factors, such as diurnal 

temperature fluctuations and the connectivity of 

cold-water refugia. 

Fish-Community Assessment

Fish-community data were acquired from recent 

fish sampling conducted by the RIDFW during 1998, 

and by the New England Regional Laboratory of the 

USEPA during 2000. The 1998 RIDFW data include 

12 samples from tributary and Queen River headwater 

streams, and 3 samples from the Usquepaug–Queen 

River mainstem. The 2000 USEPA data include only 

three samples, one each from the Queen River 

headwaters, the mainstem Queen River, and the 

mainstem Usquepaug River. Fish were sampled by 

electrofishing with direct current (DC) backpack units. 

Backpack shockers are best used in small or shallow 

streams. Backpack electrofishing was appropriate for 

sampling most reaches of the Usquepaug–Queen River 

and its tributaries during summer low flows. Backpack 

electroshockers could not be used for deeper habitats 

such as impoundments, flow-through ponds, and some 

of the deeper pools, and these reaches were not 

sampled. 

Fish were classified into three macrohabitat 

classes on the basis of their habitat use: macrohabitat 

generalists (MG), fluvial dependents (FD), and fluvial 

specialists (FS) (Bain and Knight, 1996; Bain and 

Mexler, 2000). Macrohabitat generalists, such as 

pumpkinseed and redfin pickerel, are fish species or 

size classes that use a broad range of habitat; they 

include species commonly found in lakes, reservoirs, 

and streams, and can complete their life cycle in any of 

these systems. Fluvial dependents, such as white 

suckers, require access to streams or flowing-water 

habitats for a specific life stage, but otherwise 

commonly are found in lakes and reservoirs or ponded 

habitats. Fluvial specialists, such as brook trout and 

fallfish, almost always are reported as present in 

streams or rivers and require flowing-water habitats 

throughout their life cycle (Bain and Travnichek, 

1996).

A modification of habitat classifications was 

developed by M.B. Bain (U.S. Geological Survey, 

written commun., 2000) to accommodate regional 

differences in habitat requirements. Habitat 

classifications for four species (fallfish, creekchub 

suckers, long-nose dace, brook trout) were changed 

from macrohabitat generalists to fluvial dependents or 

fluvial specialists. American eel, a catadromous fish 

that requires access to stream habitats for a portion of 

its life cycle, was classified as a macrohabitat generalist 

for the purposes of this report because it occupies a 
Study Methods 9

wide range of habitats during the portion of its life 

cycle in freshwater streams. Stocked fish, including 

Atlantic salmon and brown trout, were not included in 

the fish-community analysis. Young-of-the-year were 

included in the analysis because length-distribution 

data that could be used to separate out young-of-theyear were not available.

Determination of Streamflow

Requirements for Habitat 

Protection

A diagnostic method and four standard-setting 

methods (Instream Flow Council, 2002) were used for 

determination of streamflow requirements for habitat 

protection. The diagnostic method is the Range of 

Variability Approach (RVA) (Richter and others, 1997). 

The standard-setting methods include two office 

methods, the Tennant method (Tennant, 1976), and the 

New England Aquatic-Base-Flow (ABF) method (U.S. 

Fish and Wildlife Service, 1981; Lang, 1999); and two 

field-based methods, the Wetted-Perimeter method 

(Nelsen, 1984; Leathe and Nelson, 1986; Lohr, 1993), 

and the R2Cross method (Espegren, 1996, 1998; 

Nehring, 1979).

Methods Based on Streamflow Records

The RVA, Tennant, and New England AquaticBase-Flow methods use statistical measures of 

discharge-time series values to determine streamflow 

requirements, and require long-term records from a 

gaging station. In general, these methods should be 

applied to gaged sites only if unregulated flow data are 

available, and can be applied to ungaged sites only by 

regionalizing flow statistics at gaged sites or by 

simulating natural flows (that is, simulating 

streamflows without water withdrawals). Streamflow 

data from the Usquepaug River near Usquepaug stream 

gaging station (01117420) were used in the RVA, 

Tennant and ABF methods in this report. The 

streamflows at this gaging station are affected by 

upstream water withdrawals, but they are used in this 

report to provide an initial estimate that would provide 

a lower limit for the flow requirements determined by 

those methods. The USGS is currently developing a 

precipitation-runoff model based on the Hydrologic 

Simulation Program—FORTRAN (HSPF) program for 

analysis of the effects of water withdrawals on 

streamflow. Once the model is completed, streamflows 

without withdrawals can be simulated for the 

Usquepaug gaging station and for other locations in the 

basin; target streamflows determined by the RVA and 

streamflow requirements determined by the Tennant 

and ABF methods can then be recalculated. It is likely 

that the streamflow requirements calculated on the 

basis of simulated flows without withdrawals will be 

slightly higher than those determined from the 

historical record.

Indicators of Hydrologic Alteration and

Range of Variability Approach

Current strategies for managing, maintaining, or 

restoring riverine fishery and aquatic wildlife resources 

and processes (Poff and others, 1998; Instream Flow 

Council, 2002) suggest that the native biodiversity and 

integrity of river ecosystems can be sustained by 

maintenance of the natural pattern of flow variability 

that created that diversity. The Indicators of Hydrologic 

Alteration (IHA) and RVA methods (Richter and 

others, 1996; 1997) were developed by the Nature 

Conservancy to assess the range of variation of 

discharge for a river and to define flow targets for river 

ecosystem management. 

The IHA method characterizes the range of 

variation of discharge at a site by using a suite of 33 

hydrologic statistics. Half of these statistics measure 

the central tendancy of the magnitude or rate of change 

of flow, and half focus on the magnitude, duration, 

timing, and frequency of extreme events. The statistics 

are divided into five general groups (table 1). Flow 

statistics such as monthly means are measures of the 

magnitude of flow and are general measures of the 

availability of habitat attributes such as wetted area, 

depth, or habitat volume. Flow statistics for the 

minimum and maximum average discharge for a given 

number of consecutive days (n-day flow statistics) are 

measures of the magnitude and duration of particular 

flow and provide measures of environmental stress and 

disturbance. The timing of lowest and highest flows 

throughout the year can provide a measure of seasonal 

disturbance or stress. The frequency and duration of 

time over which a specific flow exists may determine 

whether a particular life-cycle phase can be completed 

or the degree to which stressful effects such as 

dessication can accumulate. The rate and frequency of 

change in flow may be related to the stranding of 

certain organisms along the water's edge or in pools 

(Richter and others, 1996).
10 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

In this report, the IHA is used to describe the 

range of variation of streamflows at the gaging station 

on the Usquepaug–Queen River at Usquepaug 

(01117420). The flow regime in the Usquepaug–Queen 

is mostly unaffected by water withdrawals during fall, 

winter, and spring (October to May). Streamflows in 

summer (June to September), however, are reduced 

because of water withdrawals upstream of the 

Usquepaug gaging station. Because of these 

withdrawals, and to compare flows in the Usquepaug–

Queen River to flows of nearby rivers, the IHA flow 

statistics for the Usquepaug River near Usquepaug 

gaging station (01117420) are compared to those 

determined from streamflow data from nearby rivers in 

Rhode Island, Connecticut, and Massachusetts. 

Richter and others (1997) developed an adaptivemanagement approach, known as the RVA. The RVA 

defines flow targets for river-ecosystem management 

for each of 33 flow statistics determined by means of 

the IHA. Richter and others (1997) defined these flow 

targets as either 1 standard deviation from the mean 

flow or the range between the 25th and 75th percentiles 

(the interquartile range, or IQR) of the mean flow. 

Because hydrologic data often depart from a normal 

distribution, the IQR was used as the measure of flow 

variability for this report. Different ranges could be 

used to define flow targets; for example, a recent 

release of the IHA software uses the 33rd and 66th 

percentiles to define a more narrow flow-target range 

for the RVA (Smyth Scientific Software, v. 5.0.0 Beta 

Build 3, written commun., 2002).

Tennant Method

The Tennant method bases its streamflow 

requirements on the observation that aquatic habitat 

conditions are similar in streams carrying the same 

proportion of the mean annual flow (QMA). The 

method establishes streamflow requirements by means 

of a predetermined percentage of the mean annual 

flow (Tennant, 1976), and associates aquatic habitat 

conditions with different percentages of mean annual 

flow (table 2). The Tennant method is less sensitive to 

summer water withdrawals than methods that use lowflow statistics to determine streamflow requirements, 

because the Tennant streamflow requirements are 

derived from the mean annual-flow statistic which is 

largely determined by high flows. 

The Tennant method has different criteria for 

winter (October–March) and summer (April–

September) flow periods. Minimum streamflows for 

small streams during summer are established by the 

Tennant method by use of the 40-, 30-, and 10-percent 

QMA (Annear and Conder, 1984), which represent 

good, fair, and poor habitat conditions, respectively, 

according to Tennant. At 30 percent of the QMA, most 

of the stream substrate is submerged, but at 10 percent 

of the QMA, half or more of the stream substrate can be 

exposed (Tennant, 1976). The 30-percent QMA value 

is often used to determine minimum streamflow 

requirements in summer. A modification of the Tennant 

method, used in the Canadian Atlantic Provinces, 

designates 25 percent of the QMA as the minimum 

streamflow requirement in summer (Dunbar and 

others, 1998). 

New England Aquatic-Base-Flow Method

The ABF method sets default streamflow 

requirements for use in regulated rivers, rivers that have 

a drainage area of less than 50 mi2, ungaged rivers, or 

rivers that have streamflow gaging stations that have a 

period of record of less than 25 years or that have poorquality records. The ABF-method default streamflow 

requirements are 0.5 ft3/s/mi2 for summer, 1.0 ft3/s/mi2

Table 1. Range of Variability Approach: flow statistics for 

characterization of hydrologic variation

[Source: Richter and others, 1996]

Hydrologic attribute Statistical parameter

The magnitude of monthly 

discharge 

Mean monthly discharge for each 

month.

The magnitude and duration 

of annual extreme 

discharge 

Annual minimum and maximum 

for 1-, 3-, 7-, 30-, and 90-day 

periods; number of zero-flow 

days; 7-day minimum flow 

divided by mean flow for year.

The timing of annual 

extreme discharge 

Julian date of the annual 

minimum and maximum daily 

flow.

The frequency and duration 

of high and low flow 

Number of low-flow and highflow pulses per year; mean 

duration of low-flow and highflow pulses.

The rate and frequency of 

hydrographic change

Means of all positive and 

negative flow differences 

between consecutive daily 

means; number of flow rises 

and falls.
Study Methods 11

for fall and winter, and 4.0 ft3/s/mi2 for spring (table 3). 

For free-flowing, unregulated rivers that have a 

drainage area of greater than 50 mi2, and that have 

streamflow gaging stations with good-to-excellent 

quality records and a period of record of greater than 

25 years, the ABF uses data from streamflow gaging 

stations to determine streamflow requirements. For 

these rivers, summer streamflow requirements are 

determined from the median of monthly mean flow for 

August (August median flow), fall and winter 

streamflow requirements are determined from the 

February median flow, and spring streamflow 

requirements are determined from the April and May 

median flows. August is assumed to represent the 

month of greatest stress for aquatic organisms because 

of the combination of low flows and high temperatures. 

The U.S. Fish and Wildlife Service (USFWS) 

calculates the ABF August-median flow statistic as the 

median of the monthly mean flows for August over the 

period of record (U.S. Fish and Wildlife Service, 1981; 

Lang, 1999). To make this calculation, a monthly mean 

flow statistic is first determined for each year by 

averaging the 31 daily mean flows in the month of 

August; then these monthly mean values (one for each 

year of the period of record) are combined and ranked, 

and the median value is taken. An August-median flow 

statistic can also be calculated as the median of the 

daily mean flows for all August days over the period of 

record (Charles Ritz Associates, 1987; Ries, 1997). To 

make this calculation, the 31 daily mean flows for 

August for each year are combined with the daily mean 

flows from all other August days (31 for each year of 

the period of record) and ranked, and the median value 

is taken. Consequently, "August median flow" statistics 

calculated as the median of the monthly mean flows for 

August and the median of the August daily mean flows 

are not equivalent. The USFWS method of calculating 

an August median flow statistic was designed to 

identify resource-conservative flows. Medians 

calculated from monthly mean streamflows tend to be 

higher than those calculated from daily mean 

streamflows because a small number of storms skew 

the monthly mean values upward, and the effects of 

land and water use tend to skew the daily mean values 

downward (Lang, 1999). 

Methods Based on Physical and 

Hydraulic Characteristics

The R2Cross and Wetted-Perimeter methods 

require site-specific physical and hydrological data at 

a riffle cross section. Field-data collection for the 

Wetted-Perimeter and R2Cross analyses included 

surveys of stream-channel cross sections and watersurface slopes, and field determinations of bankfull 

elevations. Several cross sections were surveyed within 

the riffles. The distance between the cross sections 

was about one channel width. Staff gages were 

installed on trees or bridge abutments to provide 

vertical control for surveying cross-section profiles and 

water-surface elevations. Landscape nails about 1 ft 

in length were installed in the streambed at multiple 

cross sections. Surveys of staff gages, bed-nails, cross 

sections and water levels were made with a laser 

theodolite. Levels were run independently at each 

site and were not surveyed to sea level. Sites were 

revisited to measure discharge and water-surface 

elevations over the nails. 

Table 2. Relations between aquatic-habitat condition and mean annual 

flow described by the Tennant method for small streams

[Source: Tennant, 1976. QMA, mean annual flow; <, less than]

Aquatic-habitat

condition for

small streams

Percentage of QMA, 

April–September

Percentage of QMA, 

October–March

Flushing flows 200 200

Optimum range 60–100 60–100

Outstanding 60 40

Excellent 50 30

Good 40 20

Fair 30 10

Poor 10 10

Severe degradation <10 <10

Table 3. Seasonal New England Aquatic-Base-Flow default streamflow 

requirements

[Source: U.S. Fish and Wildlife Service, 1981. ft3/s/mi2, cubic foot per 

second per square mile]

Season

(months) Period

Instantaneous

streamflow

(ft3/s/mi2)

Summer (mid-June to 

mid-October)

low flow 0.5

Fall/Winter (mid-October

to March)

spawning and 

incubation 

1.0

Spring (April to mid-June) spawning and 

incubation 

4.0
12 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Application of the Wetted-Perimeter and 

R2Cross methods requires development of a stagedischarge relation for a riffle and determination of 

hydraulic parameters (mean depth, mean velocity, 

and wetted perimeter) for a range of flows. Stage, 

discharge, Manning’s n, and water-surface slopes were 

used in Manning’s equation to develop stage-discharge 

relations for the surveyed riffle cross sections. 

Manning's equation is:

,

where

Stage-discharge relations and hydraulic 

parameters were determined for this report primarily by 

application of Manning’s equation to a single cross 

section by means of WinXSPRO (U.S. Department 

of Agriculture, 1998). Measurement of discharge 

and water-surface slope at low flow were used in 

Manning’s equation to determine an initial value for 

channel roughness (n). The water-surface slope was 

then used as a boundary condition and Manning’s n

was varied to calibrate the model to the water levels 

for the measured discharges. Channel roughness was 

varied linearly between the calibrated value and a 

roughness value at bankfull flow that was estimated by 

comparison of the stream channel to photographs in 

Barnes (1967) and Hicks and Mason (1991). Stream 

slope was varied for low and high flows between 

values measured at the riffle cross section, and a more 

general water-surface slope measured over a longer 

reach of the stream. For each cross section, staging 

tables were developed showing stage, mean depth, 

mean velocity, and wetted perimeter for each 

discharge. The staging tables were used to construct 

graphs for determination of streamflow requirements 

by use of the Wetted-Perimeter method, and to 

determine streamflow requirements for habitat 

protection on the basis of the R2Cross hydraulic 

criteria.

One requirement for application of Manning’s 

equation is a condition of uniform flow. Conditions that 

tend to disrupt uniform flow include bends in the 

stream course, changes in cross-section geometry, 

obstructions to flow caused by large roughness 

elements (sand bars, boulders, woody debris), or other 

channel features that cause convergence, divergence, 

acceleration, or deceleration of flow (U.S. Department 

of Agriculture, 1998). These non-uniform flow 

conditions can be evaluated if flows are gradually 

varying by use of one-dimensional, steady state, stepbackwater, water-surface-profile models such as HEC2, HEC-RAS, or WSPRO. These flow models use 

multiple cross sections, and can be used to identify 

backwater effects not accounted for by single-section 

applications of Manning’s equation. To compare 

differences between different flow models, hydraulic 

parameters were determined for two sites by use of 

Manning’s equation, with WinXSPro (U.S. Department 

of Agriculture, 1998) and by use of the U.S. Army 

Corps of Engineers' River Analysis System (HECRAS; Brunner, 2001). 

Wetted-Perimeter Method

The Wetted-Perimeter method is based on the 

assumption that there is a direct relation between the 

wetted perimeter in a riffle and fish habitat in streams 

(Annear and Conder, 1984; Lohr, 1993). The wetted 

perimeter of a stream, the width of the streambed and 

stream banks in contact with water for an individual 

cross section, is used as a measure of the availability 

of aquatic habitat over a range of discharges (Annear 

and Conder, 1984; Nelsen, 1984). Use of the 

Wetted-Perimeter method to determine streamflow 

requirements requires a plot of the relation between 

wetted perimeter and discharge (fig. 3). The streamflow 

required for habitat protection is usually chosen as 

the point of maximum curvature in this relation. 

On a stream cross section, this point theoretically 

corresponds to the break in slope at the bottom of a 

stream bank (toe-of-bank) where the water surface 

recedes from the stream banks as flows decrease, or 

rises up the banks as flows increase.

Q is discharge, in ft3/s,

1.486 is the conversion factor for use with English 

units,

n is the Manning's roughness coefficient,

A is the cross-sectional area of the channel, in ft2,

R is the hydraulic radius, in ft, and

S is the energy gradient, which was 

approximated by the friction slope, (Sf), in 

ft/ft.

Q ( ) 1.486 ⁄ n A R0.67S

0.50 =
Study Methods 13

B.

A.

WETTED PERIMETER, IN FEET

10

11

12

13

14

15

16

17

18

19

20

Break in slope

TOTAL DISCHARGE, IN CUBIC FEET PER SECOND

0 1 2 3 4 5 6 7 8 9 10

River surface

STATION, IN FEET

ELEVATION,

IN FEET

498

499

500

501

502

503

504

4,995 5,000 5,005 5,010 5,015 5,020 5,025 5,030

Wetted perimeter

Toe of bank Toe of bank

Top of bank Top of bank

Figure 3. Diagram showing example of (A) a stream-channel cross section and graph showing 

(B) the relation between wetted perimeter and discharge.
14 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Stream-channel geometry varies considerably, 

and the effectiveness of the Wetted-Perimeter method 

can be highly dependent upon the cross sections 

selected in the field. The break in slope in plots of 

wetted perimeter versus discharge is most distinct for 

channels that have sharp breaks in slope between the 

streambed and streambanks; water levels that rise 

above the bottom of the bank cause smaller rates of 

increase in wetted perimeter, and water levels that fall 

below the bottom of the bank cause larger rates of 

decrease in wetted perimeter. In practice, many 

conditions contribute to multiple breaks in slope or the 

lack of a distinct break point in the wetted-perimeterto-discharge relation. Multiple break points can 

correspond to water rising over distinct features of the 

channel such as bars, boulders, or an irregular channel 

bed or banks. Less well-defined break points may also 

be a function of the number, density, and location of 

points surveyed along a cross section. 

For this study, the most detailed cross sections 

were surveyed at the upstream ends of riffles that 

served as hydraulic controls. Hydraulic controls are 

sections or reaches of the channel, such as riffles, 

which eliminate the effects of downstream conditions 

on the velocity and depth of flow upstream of the 

section. Care was taken to survey points along the cross 

section where the slope of the streambeds or banks 

changed. When well-defined, the break in slope at the 

bottom of a stream bank was surveyed to identify the 

elevation that corresponds to a fully-wetted channel 

bed. These elevations were used to aid in establishment 

of streamflow requirements during analysis of those 

cases where break points were multiple or could not be 

clearly discerned. 

R2Cross Method

The R2Cross method requires selection of a 

critical area of the stream, such as a riffle, and assumes 

that a discharge chosen to maintain habitat in the riffle 

is sufficient to maintain fish habitat in nearby pools 

and runs for most life stages of fish and aquatic 

invertebrates (Nehring, 1979). The streamflow required 

for habitat protection in a riffle is determined from the 

flow that meets criteria for three hydraulic parameters: 

mean depth, percent of bankfull1 wetted perimeter, and 

average velocity (table 4). The depth criterion requires 

a mean depth that is at least 1/100 of the stream-top 

width, and has a lower limit of 0.2 ft. The wettedperimeter criterion requires a wetted perimeter that is at 

least 50 percent of the bankfull wetted perimeter for 

streams less than 50 ft in width, a percentage equal to 

the top width (to the nearest ft) for streams between 50 

and 60 ft in width, or 70 percent of the bankfull wetted 

perimeter for streams greater than 60 ft in width. The 

velocity criterion requires an average velocity of at 

least one foot per second (G. Espegren, Colorado Water 

Conservation Board, written commun., 2001). 

The hydraulic criteria used in R2Cross were 

developed in Colorado to quantify the amount of 

streamflow required to "preserve the natural 

environment to a reasonable degree" (Espegren, 1996). 

The R2Cross method has been found to produce 

biologic flow recommendations that are very similar to 

those determined by more data-intensive techniques 

such as the Instream Flow Incremental Methodology 

(Nehring, 1979; Colorado Water Conservation Board, 

2001).

To account for seasonal streamflow variability, 

the R2Cross method establishes different streamflow 

requirements for the summer and winter seasons. 

Streamflow recommendations in Colorado are based 

upon the streamflow that meets three hydraulic criteria 

in summer, and two of three hydraulic criteria in 

winter. In Colorado, however, flows are generally 

higher in spring and summer (April–August), because 

of snowmelt runoff, and lower in late summer, fall, and 

winter (September–March). In Rhode Island, flows are

Table 4. R2Cross criteria for hydraulic parameters for protection of 

aquatic habitat

[Source: Espegren, 1996. ft, foot; ft/s, foot per second; >, actual value is 

greater than or equal to the value shown]

Stream-top 

width

(ft)

Mean

depth 

(ft)

Percentage of 

bankfull 

wetted perimeter

(percent)

Mean

velocity

(ft/s)

1–20 0.2 50 1.0

21–40 0.2–0.4 50 1.0

41–60 0.4–0.6 50–60 1.0

61–100 0.6–1.0 > 70 1.0

________________ 1The term “bankfull discharge” is used in this report to refer to the ordinary high-water line defined by MacBroom (1998) as the level 

along the bank that separates the predominantly aquatic and terrestrial areas. This level is evident from scour marks, soils, stain lines, and 

changes in vegetation due to the prolonged presence of water.
Characterization of Stream Habitat, Temperature, and Fish Communities 15

generally lowest in midsummer and early fall (July–

September). For this study, R2Cross streamflow 

recommendations were established at flows that meet 

all three hydraulic criteria. Use of three hydraulic 

criteria will result in more conservative streamflow 

requirements from this method than use of two of three 

criteria (Annear and Conder, 1984). However, unlike 

mountain-runoff streams in Colorado, streams in 

Rhode Island have additional stresses during summer 

months that are linked to low streamflows, such as high 

stream temperatures and low dissolved-oxygen 

concentrations. The habitat quality corresponding to 

the streamflows that meet two of three R2Cross 

hydraulic criteria or that meet lower hydraulic criteria 

would need additional evaluation before being adopted 

for use in Rhode Island.

CHARACTERIZATION OF STREAM

HABITAT, TEMPERATURE, AND

FISH COMMUNITIES

The Usquepaug–Queen River can be broadly 

described as a small-order, low-gradient river. The 

mainstem portion of the river, between Route 2 and the 

confluence with Fisherville Brook, is a low-gradient 

stream that flows over a sand and gravel streambed 

through forested areas and shrub wetlands. The 

headwaters and tributaries of the river generally have a 

higher gradient and coarser bed materials than the 

mainstem, and flow through forested areas. 

 The topographic relief of the mainstem 

Usquepaug–Queen River leads to a predominance of 

low-gradient glide-and-pool habitat that has slow water 

velocities and smooth, unbroken water surfaces. The 

type of cover in this habitat is closely related to the type 

of riparian vegetation along the channel and the degree 

of canopy closure. In forested reaches where riparian 

vegetation is mostly trees and shrubs, the stream is 

typically shaded, and cover is created by woody debris 

in the channel, and by overhanging shrubs, undercut 

banks, and exposed roots along the stream margins. In 

wetland reaches where riparian vegetation is mostly 

shrubs, grass, sedge, and herbaceous vegetation, or 

wider reaches where the stream canopy is mostly open 

to sunlight, cover is created by submerged aquatic 

vegetation in the channel and by overhanging shrubs 

and emergent aquatic vegetation along the stream 

margins. 

The Usquepaug River between Routes 2 and 138 

is mostly forested glide-and-pool habitat. Downed trees 

and woody debris are common and can create narrow 

runs where trees partially block the channel or deep 

scour pools if the current is directed down into the 

streambed. The reach contains several small riffles that 

have formed where the river flows over material that 

has been eroded from a deep scour hole, where a 

narrowing of the valley has constricted the channel, or 

where the river has meandered near the sides of the 

valley and eroded into coarser substrate. Because the 

overall stream gradient is relatively low, and the drop in 

elevation over these riffles tends to be small, most 

riffles are present only during low-flow periods, and 

become fast, shallow runs when the riffles are 

submerged beneath moderate or high flows. 

The largest riffle reach on the mainstem 

Usquepaug River is between Route 138 and the Glen 

Rock Reservoir Dam in South Kingstown. Like many 

of the larger riffles in New England streams, this reach 

appears to have alterations to the channel that probably 

were caused by activities associated with the operation 

of mills. Accordingly, the channel appears to be 

straightened, and the banks are hardened with riprap. 

The Glen Rock Reservoir Dam is about 10 ft 

high, and creates an impoundment that extends 

upstream for more than a mile. The mainstem Queen 

River upstream of Glen Rock Reservoir flows mostly 

through low-gradient wetlands. Like the Usquepaug 

River, the Queen River is mostly glide-and-pool 

habitat, and the primary cover features are submerged 

aquatic vegetation and overhanging shrubs where the 

river is wide or where riparian vegetation is dominantly 

shrubs, grass, sedge, and herbaceous vegetation; and 

woody debris, undercut banks and exposed roots where 

the river passes through forested reaches. Two features 

found in the Queen River that are not common in the 

Usquepaug River are mid-channel sand bars covered 

with submerged or emergent aquatic vegetation, and 

islands and multiple channels created by channel 

avulsions. There are no large riffles in this segment, 

although there are several smaller riffles and runs that 

have gravel-and-cobble substrates.

The tributaries and headwater portions of the 

Queen River commonly have more riffle and run 

habitats than the mainstem. Fisherville and Locke 

Brooks have long reaches with moderate gradients that 

are predominantly riffle and pool habitats. Some 

reaches in the tributaries and headwaters contain glideand-pool habitat. These reaches typically are near the 
16 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

confluences of tributaries with the mainstem, where the 

tributaries extend into the lower-gradient Queen River 

Valley, or where they pass through isolated wetland 

reaches.

Habitat Assessments

Thirteen river reaches were selected to represent 

different habitats of the Usquepaug–Queen River 

and for investigation of streamflow-habitat relations. 

Seven of the sites were on the mainstems of the 

Usquepaug and Queen Rivers, and six were on the 

Fisherville and Locke Brook tributaries and in the 

Queen River headwaters (fig. 1). The river reaches 

were each about 11 channel widths in length. The 13 

sites are composed of 7 sites that include riffle habitat, 

and 6 sites that are predominantly run habitat. Some of 

the run sites become riffles at very low flows. The riffle 

sites included four on the mainstem Usquepaug–Queen 

River (U2, U1, Q6, and Q5) and three on tributary or 

headwater streams (Q3, L1, F2). The run sites included 

three on the mainstem (U3, Q8, Q7,) and three on 

tributaries or headwater streams (Q4, Q2, F1). Six of 

the riffle sites were considered to be critical and were 

also used for determination of streamflow requirements 

for habitat protection (table 5). 

Usquepaug River near Usquepaug 

(Site U3), South Kingstown

This reach is upstream of Route 2, between the 

USGS gaging station and a pull-off on the north side of 

Route 2. The drainage area to the study site is 36.1 mi2

and the river channel averages about 30 to 40 ft wide. 

The study reach is within a meandering, low-gradient 

segment of the river that is predominantly glide-andpool habitat with a sand streambed. The channel 

appears unaltered except near the bridge and where the 

river meanders close to the embankment along Route 2. 

The study reach is mostly glide, pool, and run habitats 

with a forest and shrub riparian area that partially 

shades the channel. A few patches of open canopy 

allow sunlight to penetrate to the streambed and 

facilitate growth of submerged aquatic vegetation. The 

river has numerous meanders, many of which have 

large pools on the outsides of bends. Some of these 

pools are 3 to 4 ft deep, even during periods of low 

flow. Cover in glide-and-pool habitat is mostly 

provided by downed trees, woody debris, overhanging 

shrubs, and submerged aquatic vegetation. The 

streambed through most of the reach is sand, except for 

one run, about one channel width in length, that has a 

streambed of gravel and cobbles embedded in sand. 

As water levels decline, habitat losses first 

appear along the margins of sandbars located on the 

insides of meander bends; however, moderate water 

depths remain in the pools along the outsides of the 

meander bends. During very low flows, the run 

becomes a riffle, and water depths become quite 

shallow. During extreme low flows, the edge of water 

pulls away from the banks, and woody debris and 

vegetated sandbars provides minimal or no cover 

because of shallow water conditions (fig. 4).

Usquepaug River near Laurel Lane 

(Site U2), South Kingstown

This reach is downstream of Route 138, adjacent 

to the Laurel Lanes Golf Course and about 1,100 ft 

northwest of the end of Laurel Lane. The drainage area 

to the study site is 34.0 mi2 and the river channel within 

the study reach averages about 30 to 40 ft wide. The 

study reach extends from an access road adjacent to the 

southern end of the Laurel Lanes Golf Course driving 

range to a small riffle adjacent to the northern end of 

the driving range. The study site is within a meandering 

low-gradient segment of the river that is predominantly 

glide-and-pool habitat with a sand streambed. The 

study reach includes one short riffle-and-run about one 

channel width in length. Stream velocity is mostly slow 

and depths vary throughout the reach. The channel and 

riparian zones are unaltered. The streambed is mostly 

coarse sand, except for the riffle, which has a boulder, 

cobble, and gravel streambed. The riparian vegetation 

is predominantly forest, and the channel is mostly 

shaded by trees, overhanging shrubs, and vines. Cover 

features in glides and pools are mostly provided by 

woody debris, undercut banks, overhanging shrubs, and 

deep water. Cover features in the riffle-and-run are 

provided by pockets of slower velocity water adjacent 

to boulders. An oxbow along the left bank is 

disconnected from the main channel during moderate 

and low flows. The oxbow is mostly filled with soft 

sediment and held shallow standing water during the 

early summer of 2000.
Characterization of Stream Habitat, Temperature, and Fish Communities 17

 Habitat quality was assessed by the USGS using 

the low-gradient RBP on September 13, 2000, at an 

estimated discharge of 25 ft3/s (0.74 ft3/s/mi2). The 

habitat in the reach received a score of 179. Habitat 

scores were optimal in all categories except for channel 

sinuosity, which scored suboptimal. 

Most of the habitat features in this reach are 

along the stream margins. On the outsides of meander 

bends, overhanging brush provides habitat during all 

but extreme low flows. A few deep pools on meander 

bends and beneath accumulations of woody debris may 

maintain depths of about 3 to 4 ft, even during low 

Table 5. Location and description of stations for habitat assessments, determination of streamflow requirements, temperature dataloggers, and fish 

sampling in the Usquepaug–Queen River Basin, Rhode Island

[USGS Habitat Site ID: First letter of stream name and downstream order along identified stream. Latitude is in degrees, minutes, seconds. X, activity at 

station. ID, identifier; USEPA, U.S. Environmental Protection Agency; USGS, U.S. Geological Survey; mi2, square mile]

USGS

Habitat

site ID

Station name and location

Drainage 

area

(mi2)

Latitude

o ‘ “

Longitude o ‘ “

Habitat 

assessment

Streamflow 

requirement

Temperture 

datalogger

USEPA

fish 

sampling

U3 Usquepaug River near Usquepaug, upstream of USGS 

stream-gaging station (01117420), adjacent to pulloff along north side of Route 2

36.1 41 28 36 71 36 19 X X

U2 Usquepaug River near Laurel Lane, south of 

Usquepaug, adjacent to driving range

34.0 X X X

U1 Usquepaug River at Route 138, at Usquepaug, 

between Route 138 and Old Usquepaug Road

32.8 41 30 09 71 36 30 X X X

Q8 Queen River, near Kingston Road, northeast of 

Usquepaug, adjacent to field on Eppley Audubon 

Sanctuary, 0.8 mile downstream of Liberty Road

21.2 41 31 49 71 34 44 X

Q7 Queen River at Liberty Road at Liberty, downstream 

of USGS stream-gaging station (0117370)

19.1 41 32 20 71 34 09 X X

Q6 Queen River near Dawley Road northeast of Liberty, 

0.5 mile downstream of Dawley Road

18.6 41 32 37 71 33 52 X

Q5 Queen River near Dawley Road, northeast of Liberty, 

650 feet downstream of Dawley Road

18.4 41 32 55 71 34 40 X X X X

Q4 Queen River near School Land Road, southwest of 

Exeter, 0.4 mile downstream of William Reynolds 

Road, adjacent to former Ladd School pumphouse

4.22 41 33 25 71 32 59 X X X

Q3 Queen River at William Reynolds Road, southwest of 

Exeter, downstream of William Reynolds Road

3.75 41 33 45 71 32 54 X X X

Q2 Queen River near William Reynolds Road, southwest 

of Exeter, 1,400 feet upstream of William Reynolds 

Road

3.69 41 33 57 71 32 51 X

Q1 Queen River at Route 102 west of Exeter 2.80 41 34 43 71 32 37 X

L1 Locke Brook at Mail Road, west of Liberty

downstream of Mail Road

4.37 41 32 14 71 35 17 X X X

F2 Fisherville Brook at Liberty Church Road, 400 feet 

downstream of Liberty Church Road

8.14 41 33 51 71 33 54 X X X

F1 Fisherville Brook near Pardon Joslin Road northwest 

of Exeter, 0.3 mile downstream of Pardon Joslin 

Road, downstream of impoundment on the Rhode 

Island Audubon Society Fisherville Refuge

4.0 41 35 07 71 34 15 X X
18 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

flows. Once streamflows decline to enough for the edge 

of water to pull away from the stream banks, available 

habitat decreases greatly. In shallow reaches between 

bends, woody debris becomes exposed at low flows 

and may provide only minimal habitat despite spanning 

most of the channel. Streamflows that provide a fullywetted channel across the riffle would provide 

sufficient depth for fish passage (fig. 5). At discharges 

near 15 ft3/s the channel would be fully wetted, and all 

pools would contain water, but there would be almost 

no depth at the channel margins. At some locations, the 

streambed would be exposed along the margins, and 

overhanging shrubs would extend over shallow water 

or a dry streambed. Most undercut banks would be dry 

and many roots would be exposed. 

Usquepaug River at Route 138 

(Site U1), South Kingstown

This reach is about 400 ft upstream of State 

Route 138, and downstream of Old Usquepaug Road 

in South Kingstown. The drainage area to the site is 

32.8 mi2. The study reach is within a high-gradient 

segment that is mainly riffle-and-run habitat 

A. Bend pool and exposed sandbar, upstream view

B. Submerged aquatic vegetation and overhanging 

vegetation, downstream view

A. Riffle and run habitat, upstream view

B. Woody debris, downstream view

Figure 4. Habitat features on the Usquepaug River, near Usquepaug (Site 

U3) South Kingstown, Rhode Island: (A) bend pool and exposed sandbar, 

upstream view, and (B) submerged aquatic vegetation and overhanging 

vegetation, downstream view.

Figure 5. Habitat features on the Usquepaug River near Laurel Lane (Site 

U2), South Kingstown, Rhode Island: (A) riffle-and-run habitat, upstream 

view, and (B) woody debris, downstream view.
Characterization of Stream Habitat, Temperature, and Fish Communities 19

downstream of Glen Rock Reservoir (fig. 6). The 

channel has a uniform cross section and is 25 to 35 ft 

wide. The river channel between Old Usquepaug Road 

and Route 138 is mostly straight, with a slight bend to 

the left. The channel may have been straightened, and 

the banks altered as part of a long history of mills and 

settlement at this location. However, none of the 

channel alterations appear to be recent. There is a stone 

wall along the right bank just downstream of Old 

Usquepaug Road and also upstream of the Route 138 

bridge. The right bank has been reinforced with boulder 

riprap over most of its length, and the riprap is mostly 

covered with vines and shrubs. In the downstream 

portion of the reach, the riparian area on the right bank 

is maintained as lawn up to the edge of the bank. The 

left bank appears less altered. The upper portion of the 

study reach is predominantly riffle-and-run habitat, and 

the lower end of the reach upstream of the Route 138 

bridge is run-and-pool habitat. Stream velocities are 

mostly fast throughout the reach. Depths are shallow 

(less than 1.5 ft at discharges up to about 40 ft3/s) 

between the left bank and the center of the channel, 

and are deepest adjacent to the riprap along the right 

bank. The streambed is boulder, cobble, and gravel, 

along with broken rock, brick, and other debris. The 

streambed contains little sand and may be sedimentstarved because of the impoundment upstream. Cover 

features in the riffle are provided by overhanging 

shrubs, a turbulent stream surface, and velocity shelters 

behind boulders, woody debris, and riprap. There are 

only minor amounts of woody debris and aquatic 

vegetation in the channel. The river is forested along 

the left bank, but a partially open canopy on the right 

bank and the north-south orientation of the river 

allow sunlight to reach the stream in the afternoon. 

Streamflow over the low-head dam upstream 

contributes warm water to the reach during the summer.

Habitat quality was assessed by volunteers 

and USGS teams using the high-gradient RBP on 

December 12, 1999, at a discharge of 53 ft3/s 

(1.62 ft3/s/mi2), and again on September, 21, 2000, at a 

discharge of 34 ft3/s (1.04 ft3/s/mi2) . The habitat in the 

reach received scores of 160 and 166, respectively. 

Habitat scores were mostly in the optimal range, with 

suboptimal scores related to channel alterations and the 

lack of deep-pool and slow-shallow habitat. 

Pocket water (velocity shelters) behind cobbles 

and boulders in the steambed and behind riprap along 

the right bank provide the most habitat structure in this 

reach. At discharges near 15 to 20 ft3/s the channel is 

fully wetted. There is flow over most cobbles in the 

riffle, and the tops of a few boulders are exposed. 

Overhanging shrubs extend over shallow water, and 

all pools contain water. At discharges near 10 ft3/s 

the channel remains fully wetted, and velocities are 

lower. Slightly more of the boulder tops are exposed. 

Edgewater habitats along left bank are shallower than 

those along the riprap on the right bank. Because the 

channel is mostly rectangular or trapezoidal in cross 

section, shallow conditions develop throughout the 

reach as flows decline, and a decrease in water depth to 

the top of the cobbles exposes substrate throughout the 

A. Riffle habitat, downstream view

B. Riffle habitat, upstream view

Figure 6. Habitat features on the Usquepaug River at Route 138 (Site U1), 

South Kingstown, Rhode Island: (A) riffle habitat, downstream view, and 

(B) riffle habitat, upstream view.
20 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

reach. Because of the flat streambed across the section, 

possibly created by channel alterations, low discharges 

of about 1 to 2 ft3/s will wet the channel to the bottom 

of the bank identified in the field. However, water 

depths are extremely shallow at this low discharge 

value and are below the depth of the top of the cobbles 

and boulders in the streambed.

Queen River near Kingston 

Road (Site Q8), Exeter

This reach is about 0.8 mi downstream of Liberty 

Road and about 0.4 mi upstream of the confluence of 

the Queen River and Locke Brook. The drainage area 

to the study reach is 21.2 mi2. The study site is about 

400 ft long. The river is about 30 to 40 ft wide within 

the study reach. The channel and riparian zones are 

unaltered. The study site is within a meandering, lowgradient segment of the river that is primarily glideand-pool habitat with a sand streambed. The riparian 

vegetation in the reach is mostly shrubs, with some 

habitat patchiness created by areas where there are 

trees on the stream bank or that have a higher 

percentage of trees or grass and other herbaceous 

vegetation. Stream velocity is slow and depths are 

mostly deep; the streambed is mostly soft sand. The 

remains of an old beaver dam and house were found in 

the upstream portion of the study reach. Silt and 

organic soil along the banks likely were deposited 

when there was a beaver pond at the site, and a small 

oxbow along the right bank may have been formed by 

flows bypassing the former beaver dam. Cover is 

provided by deep pools and a proliferation of 

submerged, floating, and emergent aquatic vegetation 

in shallower areas. Overhanging shrubs and vines and 

woody debris provide habitat along the stream banks 

(fig. 7). 

Habitat quality was assessed by the USGS using 

the RBP on August 8, 2000, at a discharge of 28 ft3/s 

(1.32 ft3/s/mi2), and the reach received a habitat score 

of 168. Habitat scores were optimal in all categories 

except for suboptimal scores associated with sediment 

deposition and a lack of pool variability.

Because of the low gradient, the stream channel 

tends to remain wetted bank-to-bank at low flows. 

Moderate to deep water depths remain in bend pools, 

even during low flows. As flows decline, water depths 

throughout the reach can become quite shallow over

mid-channel sand bars that have beds of submerged 

aquatic vegetation, but narrow passages between the 

vegetated bars can provide threads of current and 

deeper-water habitat adjacent to the vegetation. 

Queen River at Liberty 

Road (Site Q7), Exeter

This study site is located downstream of the 

Liberty Road bridge over the Queen River in Exeter. 

The drainage area to the site is about 19.1 mi2. The 

study reach begins downstream of the pool adjacent to 

the USGS stream-gaging station at Liberty Road, 

A. Vegetated sand bars, upstream view

B. Overhanging vegetation and deep pool, downstream 

view

Figure 7. Habitat features on the Queen River near Kingston Road (Site 

Q8), Exeter, Rhode Island: (A) vegetated sand bars, upstream view, and (B) 

overhanging vegetation and deep pool, downstream view.
Characterization of Stream Habitat, Temperature, and Fish Communities 21

(01117370), and extends for about 400 ft downstream. 

The study site is within a low-gradient reach of the river 

that is predominantly glide-and-pool habitat. The river 

is about 30 to 40 ft wide. The riparian vegetation is 

forested, and the channel is unaltered. Stream velocities 

through the reach are slow. The reach is mostly straight 

with mid-channel bars creating variable water depths. A 

few meanders provide deeper water in the bend pools. 

The streambed is mostly gravel and coarse sand. 

Cover features in the reach include undercut banks, 

overhanging shrubs, and woody debris. Submerged 

aquatic vegetation grows throughout the reach. Dense 

beds of submerged aquatic vegetation are on several 

large mid-channel bars (fig. 8). 

Habitat quality was assessed by the USGS using 

the RBP on July 29, 1999, at a discharge of 2.4 ft3/s 

(0.13 ft3/s/mi2). The habitat in the reach received a 

score of 159. Metrics for sediment deposition and 

channel sinuosity were scored suboptimal due to the 

presence of large mid-channel sand bars. The reach was 

assessed during a period of low flow. Consequently, 

metrics were scored suboptimal for available cover and 

marginal for channel-flow status. 

Once flows decline enough for the edge of 

water to recede from the banks, most undercut banks, 

overhanging vegetation, and woody debris along 

channel margins can no longer provide habitat. A few 

deeper areas continue to provide some habitat at very 

low flows. At very low flows, water depths are shallow 

throughout the reach and may be only a few tenths of a 

foot deep over mid-channel bars that have dense beds of 

submerged aquatic vegetation. 

Queen River near Dawley 

Road (Site Q6), Exeter

The study site is about 0.5 mi upstream of 

Liberty Road and 0.5 mi downstream of the Dawley 

Road bridge over the Queen River, in Exeter. The study 

site is about 400 ft long. The drainage area to the site is 

18.6 mi2. The study site is within a moderate gradient 

reach of the river and contains a mix of riffle, run, pool, 

and glide habitats. The river is about 20 to 40 ft wide. 

The riparian area is predominantly forested and 

provides partial shade to most of the study reach. The 

stream channel appears unaltered, but there has been 

some clearing of woody debris and fallen trees along 

the banks for canoe passage. Stream velocities and 

depths are variable throughout the main channel. The

streambed is mostly gravel, with sand in pooled areas. 

Cover in the channel is provided by deep water in 

bend pools, long undercut banks, overhanging shrubs, 

woody debris, and submerged aquatic vegetation 

(fig. 9). The stream has undercut the roots of many trees 

throughout the reach, some of which have dropped into 

the channel. The river has a multiple, anastamosing 

channel at some locations, possibly created during 

floods when debris jams diverted flow into the easilyeroded fine gravel and coarse sand streambanks. These 

side channels are 10 to 20 ft in width, hundreds of feet 

in length, and meander horizontally 50 ft or more from 

the main channel. The side channels provide a large 

area of shallow-water habitat. 

A. Vegetated sand bars, upstream view

B. Shallow stream margins, downstream view

Figure 8. Habitat features on the Queen River at Liberty Road (Site Q7), 

Exeter, Rhode Island: (A) vegetated sand bars, upstream view, and (B) 

shallow stream margins, downstream view.
22 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Habitat quality was assessed by volunteers and 

the USGS using the RBP on November 11, 1999, and 

the reach received a habitat score of 176. Habitat 

scores were all in the optimal range except bank 

stability, which was scored suboptimal because of the 

easily eroded banks. 

The diversity of cover features in this reach 

provide habitat throughout a wide range of flows. As 

flows recede to the base of the stream banks, undercut 

bank habitat is lost, and the quality of habitat beneath 

overhanging vegetation declines. Once the water level 

drops enough for the edge of water to pull away from 

the banks, most stream-margin habitat is lost. 

Submerged aquatic vegetation and bend pools, 

however, continue to provide habitat in the main 

channel. There is a large loss of shallow-water habitat 

once flows drop enough for the side channels to 

become disconnected from the main channel. Some 

side channels may not dry completely during low 

flows and may contain shallow, isolated pools, 

possibly fed by ground-water discharge.

Queen River at Dawley 

Road (Site Q5), Exeter

The study site begins about 650 ft downstream 

of the Dawley Road bridge over the Queen River in 

Exeter, and extends for about 400 ft downstream. The 

drainage area to the site is 18.4 mi2. The study site is 

within a low-to-moderate gradient reach of the river 

and contains a mix of habitat types. The river is about 

30 to 40 ft wide. The reach is mostly forested, partially 

shading the channel; although a few sweeping 

meanders have a wider channel and an open canopy. 

The stream channel along the left bank is unaltered. 

Some woody debris and fallen trees have been cleared 

from the channel along the right bank. The study reach 

is predominantly glide-and-pool and slow-run habitat. 

Stream velocities and depths through the reach are 

variable. The reach contains one short riffle about two 

channel widths in length. The streambed is mostly 

coarse sand and fine gravel, with some cobble and 

boulders in the riffle. Cover in the channel is provided 

by moderate depths in bend pools, long undercut 

banks, overhanging shrubs, woody debris, and 

abundant submerged aquatic vegetation (fig. 10). 

Habitat quality was assessed by volunteers and 

the USGS using the RBP on seven different dates in 

1999 and 2000. The average score for the site was 170. 

Scores ranged from 184 on September 21, 2000, at a 

discharge of 18.5 ft3/s (1.00 ft3/s/mi2) to 157 at a 

discharge of 8.8 ft3/s (0.48 ft3/s/mi2) on July 10, 2000. 

Habitat scores were mostly in the optimal range except 

for channel sinuosity which scored suboptimal. 

Metrics for available cover, velocity-depth regime, and 

channel-flow status scored suboptimal during periods 

of low flow.

As flows decline, the quality of shallow-water 

habitat along stream margins decreases. When flows 

reach the base of the bank, undercut bank habitats 

supported by tree roots are among the first cover 

features lost. Once the edge of water pulls away from 

the banks, much of the habitat associated with 

overhanging vegetation and woody debris along the 

channel margins is lost. Beds of submerged aquatic

A. Undercut trees, downstream view

B. Submerged aquatic vegetation, downstream view

Figure 9. Habitat features on the Queen River near Dawley Road (Site 

Q6), Exeter, Rhode Island: (A) undercut trees, downstream view, and (B) 

submerged aquatic vegetation, downstream view.
Characterization of Stream Habitat, Temperature, and Fish Communities 23

vegetation and bend pools can continue to provide 

some mid-channel habitat during low flows. The 

quality of that habitat appears to decrease steadily, 

however, with further decreases in water velocity and 

depth. At discharges near 30–35 ft3/s the channel is 

fully wetted. There is flow over most cobbles and 

boulders in the riffle. Overhanging shrubs in the glides 

and runs extend over shallow water at stream margins 

and undercut banks are partially filled with water. All 

pools contain water, and water depths and velocities 

through submerged aquatic vegetation are adequate to 

provide good habitat. At discharges near 10 ft3/s the 

channel remains close to fully wetted. Some edgewater 

habitats are exposed and most of the undercut banks 

are dry. Cover provided by overhanging vegetation at 

the banks is greatly reduced. The tops of some 

boulders are exposed in the riffle. Water velocity and 

depth are noticably lower in the beds of throughly 

submerged aquatic vegetation. At a discharge of 

about 4 ft3/s the channel is wetted to the left and right 

bottom-of-bank. Water depths at this discharge value 

are shallow and are near the top of the cobbles in the 

streambed. 

Queen River near New School Land 

Road (Site Q4), Exeter

This reach is located about 0.4 mi downstream of 

the William Reynolds Road bridge over the Queen 

River, and about 0.3 mi upstream of the confluence of 

the Queen River and Fisherville Brook. The drainage 

area to the reach is about 4.17 mi2. The study reach is 

200 ft long, has a low to moderate gradient, and is 

located upstream of the abandoned sewage beds and 

adjacent to the pumphouse for the former Ladd School. 

Just downstream of the study site the stream enters 

Bear Swamp, where at some locations it divides into 

multiple channels and can be hard to follow. The 

river is about 10 to 20 ft wide, about half its width 

downstream of the confluence with Fisherville Brook. 

The riparian area is predominantly forested, and the 

stream channel is unaltered. The channel is mostly 

shaded by trees and shrubs. Stream velocities and 

depths through the reach are variable. The channel is 

sinuous, and has small pools in the meanders separated 

by shallow-run habitat between bends. The streambed 

is mostly coarse sand and fine gravel. Cover in the 

channel is provided by overhanging shrubs and sedges, 

woody debris, and moderate depths in bend pools 

(fig. 11).

Habitat quality was assessed by the USGS using 

the RBP on August 8, 2000, at a discharge of 4.71 ft3/s 

(1.13 ft3/s/mi2). The habitat in the reach was scored 

at 158. The reach received suboptimal scores for 

sediment deposition and bank stability because of the 

easily eroded sand stream banks and the presence of 

sand bars. 

Portions of this reach are very shallow during 

periods of low flow. Pools on meander bends may have 

1–2 ft of water, but between pools where the channel 

commonly has a rectangular shape, water depths may 

be only a few tenths of a foot. As flows decline, pools 

can become almost isolated from one another by the

A. Riffle, upstream view

B. Left bank showing loss of stream-margin habitat at low 

flows, downstream view

Figure 10. Habitat features on the Queen River at Dawley Road (Site Q5), 

Exeter, Rhode Island: (A) riffle, upstream view, and (B) left bank showing 

loss of stream-margin habitat at low flows, downstream view.
24 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

shallow intervening water depths. Most habitat features 

are along the stream margins, and little cover remains 

in the channel once the edge of water recedes from the 

stream banks.

Queen River at William Reynolds 

Road (Site Q3), Exeter

This reach is downstream of William Reynolds 

Road in Exeter. The study site is within a reach of the 

river with a low to moderate gradient. The drainage 

area to the site is about 3.75 mi2. The study reach 

contains a mix of riffle, run, and pool habitats in 

approximately equal distribution. The river is about 

20 ft wide. A forested riparian area creates a closed 

canopy that shades the channel throughout most of 

the reach. The study reach is mostly unaltered; 

however, the stream channel may have been 

straightened in the reach immediately downstream of 

the culverts beneath William Reynolds Road. The 

streambed is predominantly coarse sand and gravel 

except for a riffle about 50 ft downstream of William 

Reynolds Road, where the bed is cobble and gravel. 

Stream velocities and depths are variable along the 

reach. Midway through the study reach, two sharp 

meanders have created deep pools along the outside 

and sandbars on the inside of the meander bends. The 

stream banks are sand and gravel, and are undercut 

about a foot into the bank along most of the reach. 

Cover features in the reach are provided by undercut 

banks, bend pools, overhanging vegetation, and woody 

debris (fig. 12). 

Habitat quality was assessed by volunteers using 

the RBP during training sessions on September 14, 

1999, and June 14 and 24, 2000. The mean score 

assigned to the reach by the USGS and volunteer 

groups in September 1999 was 167. The habitat 

assessments were conducted during a period of low 

flow, and metrics for channel-flow status and 

velocity/depth regime were scored suboptimal. 

Streamflows were higher during the assessments made 

on June 14 and 24, 2000, and this was reflected in the 

mean scores which were 181 and 184, respectively. 

Metrics were scored suboptimal for velocity-depth 

regime because of the absence of deep pools. An 

assessment made by the USGS on July 12, 2000, at a 

discharge of about 0.93 ft3/s (0.25 ft3/s/mi2) scored 

172, and velocity/depth regime and channel-flow status 

were scored suboptimal. An additional assessment 

at a discharge of about 7.3 ft3/s (1.9 ft3/s/mi2) on 

September 20, 2000, gave a score of 186. 

As water levels decline, habitat losses are first 

visible in the riffle at the upper end of the study reach. 

Most of the riffle has a rectangular cross section and 

when flows drop to the bottom of the bank, water 

depths become very shallow, and the tops of cobbles 

are exposed. Once substrates are exposed, little depth 

remains in the riffle to provide habitat or fish passage 

between the cobbles. Any woody debris that lies on 

top of the rocky streambed also is exposed at low flow,

A. Shallow water, upstream view

B. Loss of habitat at stream margins, upstream view

Figure 11. Habitat features on the Queen River near School Land Road 

(Site Q4), Exeter, Rhode Island: (A) shallow water, upstream view, and 

(B) loss of habitat at stream margins, upstream view.
Characterization of Stream Habitat, Temperature, and Fish Communities 25

and the undercut banks along the channel become too 

shallow to provide quality habitat, or are dry. In the 

lower end of the study reach, bend pools maintain 

moderate water depths as flows decline, but large 

habitat losses occur in the reaches between pools, 

where the sand and gravel that has been scoured 

out of the pools is deposited. On several occasions in 

1999 small fish that were disturbed by wading were 

observed attempting to swim sideways through water 

about 1 in. deep to try to gain passage to upstream 

pools. At discharges near 6 ft3/s, the tops of small 

boulders are exposed in the riffle, but the undercut 

banks are partly full and the channel is close to fully 

wetted. Some edgewater habitats are exposed, 

particularly in sandbars on the inside of meander 

bends.

Queen River near William Reynolds 

Road (Site Q2), Exeter

This reach is about 0.2 mi upstream of William 

Reynolds Road, and about 1 mi downstream of 

Route 102 in Exeter. The drainage area to the site is 

about 3.69 mi2. The reach is located upstream of a 

small impoundment and downstream of the Exeter 

Country Club. The study site is within a reach of the 

river with a low to moderate gradient. Parts of the 

channel have been altered, although none of these 

alterations appear recent. There is a small constructed 

rock control at the lower end of the reach, and some 

portions of the channel have boulders that appear to 

have been placed along the banks to reduce erosion. 

The river is about 10 to 20 ft wide. The reach is 

predominantly glide-and-run habitat. The stream is 

narrow and the channel is shaded by riparian trees and 

shrubs. The streambed consists of a mix of gravel, 

cobbles, boulders, and coarse sand. Many downed trees 

and pieces of small woody debris are in the channel, 

and the stream banks have exposed roots and are 

undercut by about 0.5 ft throughout the reach. Depths 

and velocities in the stream are variable (fig. 13).

Habitat quality was assessed by volunteer groups 

using the RBP on October 15, 1999, at a discharge 

of about 2.4 ft3/s (0.65 ft3/s/mi2), and again on 

July 14, 2000, at a discharge of about 1.4 ft3/s 

(0.38 ft3/s/mi2). The habitat in the reach was scored at 

168 in October and 161 in July. The reach is relatively 

straight and received suboptimal scores for sediment 

deposition, velocity-depth regime, channel-flow status, 

channel alteration, and frequency of riffles.

Overhanging shrubs and woody debris provide 

most of the habitat throughout the study reach. Once 

flows drop enough for the edge of water to pull away 

from the banks, the undercut banks along the channel 

become dry, and water depths beneath overhanging 

vegetation are very shallow. Because the channel is 

narrow, many of the trees that have fallen into the 

stream bridge the channel. These trees provide 

overhead cover, but are commonly out of the water 

and exposed even at moderate flows.

A. Riffle with rectangular cross section during low flow, 

downstream view

B. Loss of stream-margin habitat, upstream view

Figure 12. Habitat features on the Queen River at William Reynolds Road 

(Site Q3), Exeter, Rhode Island: (A) riffle with rectangular cross section 

during low flow, downstream view, and (B) loss of stream-margin habitat, 

upstream view.
26 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Locke Brook at Mail Road 

(Site L1), Exeter

This reach is downstream of Mail Road in Exeter. 

The drainage area to the site is 4.37 mi2. 

The study site has a moderate gradient and is 

predominantly riffle habitat. The study reach begins 

about 300 ft downstream of the Mail Road bridge, and 

extends about 600 ft downstream to a pool and large 

debris pile at a sharp bend in the river. The upper 

portion of the reach is lined with grass, sedge, and 

shrubs and has an open canopy, and the lower portion 

of the reach is lined with shrubs and trees and has a 

partly closed canopy. The channel and riparian area 

show evidence of alterations. The adjacent farm uses a 

wide, shallow riffle in the upstream portion of the reach 

as a ford for tractors to cross the brook, and the riparian 

area at the upstream end of the reach is mowed for hay 

within a few feet of the stream. The river is 20–30 ft 

wide. The reach is predominantly riffle-and-run habitat 

with a coarse sand, gravel, cobble, and boulder 

streambed. Cover in the upper portion of the reach is 

provided by submerged aquatic vegetation, and by 

velocity shelters behind cobbles and boulders. The 

stream is shallow; low banks and sedge hummocks line 

the channel in the upper portion of the reach. In the 

lower portion of the reach, cover is provided by 

overhanging shrubs, undercut banks, and woody 

debris. There are two shallow pools in meander bends 

at the downstream end of the reach. A drop over the 

downstream end of the culvert under Mail Road creates 

a barrier to upstream fish passage between the study 

reach and the headwaters of Locke Brook 

(fig. 14).

Habitat quality was assessed on three different 

dates between November 1999 and September 2000 

by volunteer and USGS teams using the RBP. Habitat 

quality was assessed by the USGS on July 12, 2000, 

at a discharge of about 3.3 ft3/s (0.76 ft3/s/mi2), and 

received a score of 147. Habitat quality was assessed 

by volunteer teams on July 18, 2000, at a discharge 

of about 3.4 ft3/s (0.78 ft3/s/mi2), and received a score 

of 154. Habitat quality was assessed by the USGS 

and volunteers on August 11, 2000, at a discharge of 

about 4.6 ft3/s (1.05 ft3/s/mi2), and received a score of 

162. Habitat scores were mostly in the optimal range, 

but were marginal to suboptimal for pool variability, 

and suboptimal for channel-flow status and bankvegetation protection. The reach received scores in the 

poor range for riparian vegetative zone width because 

of the removal of vegetation along the stream banks. 

When water levels decline enough for the top of 

the substrate to become exposed, most pocket-water 

habitat is lost throughout the stream channel, and

A. Woody debris, upstream view

B. Loss of stream-margin habitat

Figure 13. Habitat features on the Queen River near William Reynolds 

Road (Site Q2), Exeter, Rhode Island: (A) woody debris, upstream view, and 

(B) loss of stream-margin habitat.
Characterization of Stream Habitat, Temperature, and Fish Communities 27

habitat quality in undercut banks and beneath 

overhanging vegetation is poor. In the upstream 

portions of the reach, the area of shallow-water habitat 

that extends into emergent vegetation along the stream 

margins decreases as water levels decrease. Beds of 

submerged aquatic vegetation provide some habitat at 

low flows, but the quality of that habitat declines as 

water depth decreases. At discharges near 3 ft3/s the 

channel is close to fully wetted, but the tops of cobbles 

and boulders are exposed in the riffle. Some edgewater 

habitats are exposed. The water depths are shallow in 

velocity-shelter habitat downstream of boulders. Water 

velocity remains good through beds of submerged 

aquatic vegetation. 

Fisherville Brook at Liberty Church 

Road (Site F2), Exeter

This reach is about 400 ft downstream of the 

Liberty Church Road bridge over Fisherville Brook in 

Exeter. Drainage area to the site is 8.14 mi2. The site 

begins several hundred feet downstream of the bridge, 

and extends about 200 ft downstream from the point 

where a side channel along the left bank joins the main 

channel. The reach has a moderate gradient and 

includes several riffles. Although the stream channel 

appears to be natural, a side channel on the left bank 

and an old foundation on a hill near the right bank 

indicate that the stream upstream of the reach may 

have been altered historically. The brook in this 

reach is about 20 ft wide and mostly shaded by trees 

and overhanging shrubs along the forested banks. 

The reach is predominantly riffle-and-run habitat 

with a coarse sand, gravel, and cobble streambed. 

Cover in the riffle is provided by turbulent stream 

surfaces and velocity shelters behind cobbles, boulders, 

and woody debris in the channel. Some of the boulders 

are covered with aquatic moss, which provides habitat 

for invertebrates. The streambed also contains some 

metal and other debris. The downstream portion of the 

reach has several shallow pools and one long pool 

which has water depths of about 3 ft during low flow. 

Cover in the pools is mostly provided by water depth, 

overhanging shrubs, woody debris, and undercut banks 

(fig. 15). 

Habitat quality was assessed by volunteer and 

USGS teams using the RBP on November 17, 1999, at 

a discharge of about 12 ft3/s (1.47 ft3/s/mi2). The 

habitat in the reach received a score of 191, one of the 

highest scores assigned during the study. Habitat 

quality was assessed on two other dates and received 

scores of 184 on July 11, 2000, at a discharge of about 

4.8 ft3/s (0.59 ft3/s/mi2), and 190 on September 20, 

2000, at a discharge of about 9.6 ft3/s (1.18 ft3/s/mi2). 

Habitat scores were mostly in the optimal range. 

Metrics for velocity-depth regime and channel-flow 

status were scored suboptimal during July low flows.

A. Riffle, upstream view

B. Riffle, downstream view

Figure 14. Habitat features on Locke Brook at Mail Road (Site L1), Exeter, 

Rhode Island: (A) riffle, upstream view, and (B) riffle, downstream view.
28 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

As water levels drop, the quality of pocket 

water behind cobbles and boulders decreases. Once 

water levels reach the bottom of the banks, most 

undercut bank and exposed root habitat is lost, and 

the tops of boulders become exposed. When water 

levels drop enough for the edge of water to pull away 

from the banks, shelter beneath overhanging shrubs is 

lost in the riffle-and-run portions of the reach. In the 

glide-and-pool portions of the reach, the channels are 

deep and narrow and overhanging shrubs continue to 

provide cover even at extremely low flows. Under 

these conditions, however, the quality of glide-andpool habitat declines because of lowered stream 

velocities. At discharges near 5 ft3/s the channel is 

close to fully wetted. The tops of boulders are exposed 

in the riffle. Some edgewater habitats are exposed, and 

overhanging vegetation at the banks provides some 

cover, but over shallow water. 

Fisherville Brook near Pardon Joslin 

Road (Site F1), Exeter

This reach is about 0.3 mi downstream of Pardon 

Joslin Road, and downstream of an impoundment on 

the Rhode Island Audubon Society Fisherville refuge, 

in Exeter. The drainage area to the site is 4.22 mi2. The 

study site is within a low-gradient reach of the river. 

The channel downstream of the impoundment may 

have been straightened, or otherwise altered because 

of its close proximity to the impoundment. The 

impoundment likely reduces the transport of sediment 

into the reach from upstream. Ground-water seepage 

from the remains of a small canal enters the stream 

from the right bank. The bed of the canal is covered 

with orange iron-bacteria deposits. A stand of mature 

hemlock shades the channel throughout the reach. The 

river is narrow, about 15 ft wide. Woody debris is 

abundant in the channel. The reach consists of 

predominantly low-gradient riffle, run, and pool 

habitats with a coarse sand and gravel streambed. 

Several large boulders (more than 2 ft in diameter) are 

scattered throughout the lower portion of the reach. 

The pools are shallow (less than 1.5 ft) at low flow. 

Cover in the reach is provided primarily by woody 

debris and undercut streambanks (fig. 16). 

Habitat quality was assessed on two different 

dates in 1999 and 2000 by volunteer and USGS teams 

using the RBP. The habitat in the reach received scores 

between 178 and 189. Habitat scores were mostly in 

the optimal range.

Undercut bank and exposed-root habitat is lost 

when water levels drop enough for the edge of the 

stream to recede from the banks. The channel is 

narrow, so woody debris that bridges the channel is 

exposed even at moderate flows. At discharges near 2–

3 ft3/s, water depths are very shallow at the edge of 

water and in the undercut banks, and the streambed on 

the sandbar on the inside bend of the meander is 

exposed.

Summary of Habitat Variability with Flow

Streamflows that provide good habitat in riffles 

also seem to provide good habitat in nearby run and 

glide-and-pool habitats. Habitat in riffle reaches is

A. Riffle, downstream view

B. Riffle, downstream view

Figure 15. Habitat features on Fisherville Brook at Liberty Church Road 

(Site F2), Exeter, Rhode Island: (A) riffle, downstream view, and (B) riffle, 

downstream view.
Characterization of Stream Habitat, Temperature, and Fish Communities 29

provided by localized pockets of moderately deep 

water, velocity shelters behind cobbles and boulders, 

and by overhanging vegetation along stream margins. 

These features provide good habitat at streamflows that 

cover the substrate to depths suitable for fish passage, 

fully wet the channel bed, and provide water depths 

along the edges of the channel that are adequate for 

stream-margin habitat features to be usable. Cover 

features in run and glide habitats are mostly associated 

with the stream margins and banks. These features 

provide good habitat when the streamflow is great 

enough to fully wet the channel bed, and water depths 

along the edges of the channel are adequate for the 

stream-margin habitat features to be usable. In pools 

and low-gradient wetland reaches of the Usquepaug–

Queen River, habitat and cover is provided by stream 

margin habitat and also by submerged and emergent 

aquatic vegetation. Water depth alone provides some 

habitat in pools. Reaches that have a diversity of cover 

features are more likely to maintain some amount of 

cover over a wide range of flows. Most of the sites in 

this study that were unaltered scored relatively high 

using the RBP during periods of moderate flow, 

indicating that these sites represent places that have 

good habitat and could contribute to the health of the 

river were adequate flows maintained. 

In general, habitat availability does not decrease 

uniformly as flows decline. Large areas of habitat can 

become unavailable over a small range of discharge 

as streambeds and stream-margin habitat become 

exposed. Evaluation of stream habitat at different flows 

reveals that each type of channel geomorphic unit 

(riffle, run, glide, or pool) tends to have characteristic 

changes in habitat in response to declining streamflow. 

Although the scale of changes in stage in response to 

declining streamflow is roughly proportional to the 

drainage area of a site, the process by which habitats 

are lost in each type of channel geomorphic unit tends 

to be similar regardless of position within a stream 

system. 

Reaches that have high gradients, such as riffles, 

undergo rapid changes in habitat availability and 

quality as flows decline. Riffles and higher-gradient 

runs that have rectangular or trapezoidal cross sections 

develop shallow water conditions very quickly as 

flows decline, and are among the best locations for 

monitoring the variability of habitat with streamflow. 

Once decreases in water depth expose the tops of 

cobble substrate, little depth may remain to provide 

useful habitat or fish passage. Habitat in low-tomoderate gradient reaches, such as glides and lowgradient runs, is mostly associated with channel 

margins. Once water levels recede to the base of the 

stream banks, undercut bank habitat is lost, and the 

quality of habitat beneath overhanging vegetation is 

poor because of shallow water depths. When the edge 

of water recedes from the banks, the habitat provided 

by most cover features, such as woody debris, 

overhanging vegetation, undercut banks, and exposed 

roots, is lost. Large losses of shallow habitat also can 

occur when flows decline far enough for side channels 

to become disconnected from the main channel. Water 

depths in low-gradient reaches, such as pools, 

generally remain deeper than in moderate-to-highgradient reaches. As flows decline, overhanging 

A. Woody debris, downstream view

B. Run, upstream view

Figure 16. Habitat features on Fisherville Brook near Pardon Joslin Road, (Site 

F1), Exeter, Rhode Island: (A) woody debris, downstream view, and 

(B) run, upstream view.
30 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

vegetation on steep banks on the outside bends of pools 

can provide cover long after the edge of water has 

receded from the stream banks in other areas of the 

pool. Other cover features in the channel may provide 

cover even during very low flows. For example, narrow 

passages between beds of aquatic vegetation can 

provide habitat even though adjacent vegetated midchannel bars are exposed; and scour holes beneath or 

adjacent to trees that have fallen into the channel may 

provide moderately deep habitat with some overhead 

cover even when water depths between pools have 

become low enough to isolate the pools. However, 

other factors that are directly or indirectly affected by 

decreasing flows, such as decreased water velocities 

and elevated temperatures, may also act to reduce 

habitat quality during low flows. In general, for reaches 

of all gradients, as flows decline and habitat becomes 

unavailable, the quality of remaining habitat also 

declines. 

Stream Temperature

Water-temperature data were collected at eight 

sites in the Usquepaug–Queen River between June 23 

and September 25, 2000 (table 5). To assess the 

suitability of summer stream temperatures for coldwater fish species, stream temperatures were compared 

to critical and optimum ranges for brook trout and 7-

day moving means of daily maximum stream 

temperatures were compared to maximum weekly 

average temperatures (MWAT) and short-term maxima 

(STM) survival temperatures. Brook trout were 

selected for the comparisons because of state and local 

concerns regarding maintenance of brook trout in the 

Usquepaug–Queen River, and because water 

temperature is the single most important factor limiting 

brook trout populations (Picard, 1995). 

In general, stream temperatures below 68°F are 

considered favorable for brook trout. The upper critical 

range for brook trout is 68–84°F (Elliot, 1994). The 

upper critical range is the temperature range over 

which a significant disturbance in the normal behavior 

of a fish may occur, ranging from cessation of feeding 

to death. Sustained stream temperatures greater than 

77.5°F are generally lethal for brook trout. During 

prolonged warm periods, populations of brook trout 

can exist in thermally marginal streams only if 

sufficient cold-water refugia exist, such as springs or 

pools that receive cool ground-water discharge. The 

distribution and abundance of brook trout in relation to 

temperatures of local coolwater refugia were not 

measured in this study. Stream temperatures recorded 

at the study sites likely represent the overall stream 

temperature, and therefore should be used only to 

provide a general indication of the suitability of 

summer stream temperatures for cold-water fish 

species.

To illustrate differences in stream temperatures 

between the study sites, the seven-day moving mean of 

daily maximum stream temperature was calculated for 

each site and then compared to maximum weekly 

average temperature (MWAT) and short-term maxima 

(STM) survival temperature criteria for brook trout 

(fig. 17).

The maximum temperatures observed were 

80.2 and 79.6°F in the headwaters of the Queen 

River at Route 102 and William Reynolds Road, 

respectively. The 7-day mean of the daily maximum 

stream temperatures at these sites was greater than 

68°F for all but a few days in mid-September. Stream 

temperatures at these sites were in the upper critical 

range for brook trout (over 68°F) for 62 percent of the 

time at the Route 102 site and 53 percent of the 

time at the William Reynolds Road site. The warm 

stream temperatures in the headwaters of the Queen 

River are possibly caused by the combined effects of 

the small extent of sand and gravel aquifer in the 

contributing area to the study sites, the presence of 

several small impoundments, and the removal of 

riparian vegetation from some of the reaches.
Characterization of Stream Habitat, Temperature, and Fish Communities 31

OPTIMUM RANGE

UPPER CRITICAL RANGE

OPTIMUM RANGE

UPPER CRITICAL RANGE

06/23 06/30 07/07 07/14 07/21 07/28 08/04 08/11 08/18 08/25 09/08 09/01 09/15 09/22

B. QUEEN RIVER AT WILLIAM REYNOLDS ROAD

7-DAY MOVING MEAN OF DAILY STREAM TEMPERATURE

MAXIMUM WEEKLY AVERAGE TEMPERATURE (MWAT) FOR 

GROWTH OF JUVENILES AND ADULTS

SHORT-TERM MAXIMUM (STM) SURVIVAL TEMPERATURE

STREAM TEMPERATURE

85

80

75

70

65

60

55

50

TEMPERATURE, IN DEGREES FAHRENHEIT

2000

EXPLANATION

85

80

75

70

65

60

55

50

A. QUEEN RIVER AT ROUTE 102

Figure 17. Stream temperature in the Usquepaug–Queen River, Rhode Island, June to September 

2000: (A) Queen River at Route 102, Exeter, (B) Queen River at William Reynolds Road, Exeter, 

(C) Fisherville Brook at Liberty Church Road, Exeter, (D) Queen River at Dawley Road, Exeter, 

(E) Queen River at Liberty Road, Exeter, (F) Locke Brook at Mail Road, Exeter, (G) Usquepaug River 

at Route 138, South Kingstown, and (H) Usquepaug River at Route 2, South Kingstown.
32 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

OPTIMUM RANGE

UPPER CRITICAL RANGE

85

80

75

70

65

60

55

50

TEMPERATURE, IN DEGREES FAHRENHEIT

QUEEN RIVER AT DAWLEY ROAD

55

50

60

65

70

75

80

85

OPTIMUM RANGE

UPPER CRITICAL RANGE

70

QUEEN RIVER AT LIBERTY ROAD

OPTIMUM RANGE

50

55

60

65

70

75

80

85

FISHERVILLE BROOK AT LIBERTY CHURCH ROAD

UPPER CRITICAL RANGE

C.

D.

E.

06/23 06/30 07/07 07/14 07/21 07/28 08/04 08/11 08/18 08/25 09/08 09/01 09/15 09/22

2000

Figure 17. Stream temperature in the Usquepaug–

Queen River, Rhode Island, June to September 2000: 

(A) Queen River at Route 102, Exeter, (B) Queen River 

at William Reynolds Road, Exeter, (C) Fisherville Brook 

at Liberty Church Road, Exeter, (D) Queen River at 

Dawley Road, Exeter, (E) Queen River at Liberty 

Road, Exeter, (F) Locke Brook at Mail Road, Exeter, 

(G) Usquepaug River at Route 138, South Kingstown, 

and (H) Usquepaug River at Route 2, South 

Kingstown—Continued.
Characterization of Stream Habitat, Temperature, and Fish Communities 33

2000

F.

G.

H.

50

55

60

65

70

75

80

85

OPTIMUM RANGE

UPPER CRITICAL RANGE

TEMPERATURE, IN DEGREES FAHRENHEIT

USQUEPAUG RIVER AT ROUTE 138

50

55

60

65

70

75

80

85

OPTIMUM RANGE

UPPER CRITICAL RANGE

USQUEPAUG RIVER AT ROUTE 2

06/23 06/30 07/07 07/14 07/21 07/28 08/04 08/11 08/18 08/25 09/08 09/01 09/15 09/22

50

55

60

65

70

75

80

85

LOCKE BROOK AT MAIL ROAD

OPTIMUM RANGE

UPPER CRITICAL RANGE

Figure 17. Stream temperature in the Usquepaug–

Queen River, Rhode Island, June to September 2000: 

(A) Queen River at Route 102, Exeter, (B) Queen River 

at William Reynolds Road, Exeter, (C) Fisherville Brook 

at Liberty Church Road, Exeter, (D) Queen River at 

Dawley Road, Exeter, (E) Queen River at Liberty 

Road, Exeter, (F) Locke Brook at Mail Road, Exeter, 

(G) Usquepaug River at Route 138, South Kingstown, 

and (H) Usquepaug River at Route 2, South 

Kingstown—Continued.
34 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

The minimum temperatures observed were 53.2 

and 53.7°F for the mainstem Queen River at Dawley 

Road and at Mail Road, respectively. Stream 

temperatures at these sites were in the upper critical 

range for brook trout (over 68°F) for 22 percent of the 

time at the Dawley Road site and 14 percent of the time 

at the Mail Road site. Most of the time, however, 

stream temperatures in this reach are near the upper 

end of the optimum range of temperatures for brook 

trout, between about 62 and 67°F. The Dawley Road 

site had the greatest range of diel temperatures during 

the study period, about 9.5°F, and averaging about 

6.1°F. Upstream of Dawley Road, the mainstem Queen 

River receives cool-water discharge from Fisherville 

Brook. Downstream of Mail Road, the Queen River 

receives additional cold-water inputs from Locke 

Brook. The cooler stream temperatures in this segment 

of the mainstem Queen River are possibly caused by 

the combined effects of ground-water discharge to the 

stream, shading of the stream channel, and the input of 

cool water from tributaries.

Data collected at the Route 138 study site show 

that water temperatures increase after the water passes 

through Glen Rock Reservoir, creating stream 

temperatures in the Usquepaug River that are marginal 

to poor for brook trout. Water temperatures in the 

Usquepaug River at Route 138 are warmer by about 

6°F in comparison to the mainstem Queen River 

upstream. Stream temperatures at these sites were in 

the upper critical range for brook trout (over 68°F) for 

59 percent of the time at the Route 138 site and 42 

percent of the time at the Route 2 site. The Route 2 site 

had the smallest range of diel temperatures during the 

study period, about 4.7°F, and averaging about 3.3°F. 

Stream temperatures in the Usquepaug River at Route 2 

are slightly lower than those at Route 138 possibly 

because of ground-water inputs to the river and shading 

of the stream channel.

The temperature of stream water can increase as 

the amount of ground water discharging to a stream is 

reduced (Baevsky, 1991; Stark and others, 1994; 

Picard, 1995). Decreased stream discharge also 

results in a smaller thermal mass that would be 

more susceptible to warming from solar radiation. 

Consequently, further reductions in stream discharge 

or increases in ground-water withdrawals could 

increase stream temperatures and thus degrade the 

habitat for brook trout in summer. Although this study 

did not determine how reservoirs and current waterwithdrawal and land-use practices may be affecting 

stream temperatures, the stream temperatures in the 

Usquepaug River and Queen River headwaters were 

marginal for brook trout in the summer of 2000, and 

cold-water fish communities that exist in these reaches 

would appear to have little tolerance for temperature 

increases that could be created by increased surface or 

well-water withdrawals, or the inputs from stormwater 

discharges or impoundment overflows. 

Fish-Community Assessment

Fish data collected by the Rhode Island Division 

of Fisheries and Wildlife in 1998 and the USEPA in 

2000 were combined and then grouped into mainstem 

and tributary datasets for analysis (table 6). The 

mainstem grouping included all samples from the 

Usquepaug River and samples from the Queen River 

downstream of the junction of the Queen River with 

Fisherville Brook. The tributary grouping included all 

samples from tributaries and from the headwaters of 

the Queen River upstream of the junction of the Queen 

River with Fisherville Brook. 

In 1998 and 2000, 811 fish of 18 different 

species were collected at 5 sites on the mainstem. The 

fish communities in the mainstem were dominated by 

Eastern brook trout, redfin pickerel, tesselated darter, 

American eel, white sucker, and fallfish, composing by 

number 25, 17, 15, 10, 9, and 9 percent of the mainstem 

samples, respectively. The remaining 12 species each 

made up less than 5 percent of the total number of fish 

collected. In the tributaries, 1,224 fish of 14 different 

species were collected at 13 sites. Eastern brook trout, 

Atlantic salmon, and fallfish were the most numerous, 

composing by number, 56, 27, and 5 percent of the 

tributary samples, respectively. The remaining 11 

species each made up less than 5 percent of the total 

number of fish collected.

In accordance with habitat-use classifications 

developed by Bain (U.S. Geological Survey, written 

commun., 2000), fish species sampled in the 

Usquepaug–Queen River were divided into one of three 

macrohabitat classes: macrohabitat generalists, fluvial 

dependents, and fluvial specialists (table 7). Atlantic 

salmon, which are stocked, were not included in the 

analysis. The RIDFW and USEPA data did not include 

length-frequency information which could have been 

used to distinguish native from stocked brook trout, so 

all brook trout were included in the analysis. Fish in the 

Usquepaug–Queen River mainstem consisted of 52
Characterization of Stream Habitat, Temperature, and Fish Communities 35

percent fluvial-specialist, 9 percent fluvial-dependent, 

and 39 percent macrohabitat-generalist species 

(fig. 18). Fish in tributaries and headwaters of 

the Queen River consisted of 85 percent fluvialspecialist, 6 percent fluvial-dependent, and 9 percent 

macrohabitat-generalist species.The fish-community 

composition of mainstem rivers typically consists of 

lower percentages of fluvial species than the tributaries 

(M.B. Bain, USGS, oral commun., 2002).

Historical fish data collected between 1962 and 

1965 (Guthrie and others, 1973) were reviewed to 

compare the fish-community composition of the 

Usquepaug–Queen River to recent fish data, collected 

by the Rhode Island Division of Fisheries and Wildlife 

in 1998 and the USEPA in 2000. The comparison 

showed that the 1998–2000 fish collection contained 

five macrohabitat generalist species not collected in 

1962–65 (bluegill, brown bullhead, golden shiner, 

pumpkinseed, and yellow perch) along with one fluvial 

specialist (Atlantic salmon, which is stocked). Brown 

trout (stocked), was the only species present in the 

historical data that was not detected in the 1998 and 

2000 samples. 

Habitat-use classifications for the mainstem 

Usquepaug–Queen fish community were compared to 

habitat-use classifications for target fish communities 

developed for the Quinebaug River (Bain and 

Mexler, 2000), and Ipswich River (Ipswich River 

Fisheries Restoration Task Group, 2002). Target fish 

communities are model fish communities that have 

been defined to be appropriate for a natural river. The 

Quinebaug target fish community can be used as a 

general guide of what is considered a healthy fish 

community for large inland streams and small rivers in

Table 6. Number of each species and percent of total number of fish collected in the mainstem and tributaries of the Usquepaug–Queen River, Rhode 

Island, by the U.S. Environmental Protection Agency New England Regional Laboratory in 2000 and the Rhode Island Division of Fish and Wildlife in 1998

[Mainstem: Usquepaug River and Queen River downstream of Fisherville Brook. Tributaries: Tributaries to the Queen River and the headwaters of the Queen 

River upstream of Fisherville Brook. Species: Species are ranked by percent of total. Percent: Percent of the total number of fish collected for the mainstem 

and for the tributaries for each species]

Species Number collected Percent Species Number collected Percent 

Mainstem Tributaries

Brook Trout 201 25 Brook Trout 686 56

Redfin Pickerel 135 17 Atlantic Salmon 333 27

Tesselated Darter 121 15 Fallfish 60 5

American Eel 77 10 White Sucker 53 4

Fallfish 74 9 Redfin Pickerel 38 3

White Sucker 74 9 Swamp Darter 12 1

Pumpkinseed 34 4 American Eel 11 <1

Atlantic Salmon 30 4 Brown Bullhead 7 <1

Bluegill 15 2 Largemouth Bass 6 <1

Golden Shiner 14 2 Bluegill 6 <1

Yellow Perch 10 1 Golden Shiner 5 <1

Brown Bullhead 5 <1 Banded Sunfish 4 <1

Largemouth Bass 5 <1 Pumpkinseed 2 <1

Chain Pickerel 5 <1 Common Shiner 1 <1

Creek Chubsucker 5 <1 Blacknose Dace 0 0

Banded Sunfish 3 <1 Tesselated Darter 0 0

Blacknose Dace 2 <1 Creek Chubsucker 0 0

Bridal Shiner 1 <1 Chain Pickerel 0 0

Common Shiner 0 <1 Yellow Perch 0 0

Swamp Darter 0 0 Bridal Shiner 0 0

All species 811 100 All species 1,224 100
36 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Southern New England (Bain and Mexler, 2000). The 

Ipswich target fish community is used to show what is 

considered a healthy fish community for a small coastal 

river. Fish in the Quinebaug target fish community 

had a population consisting of 55 percent fluvial 

specialists, 27 percent fluvial dependents, and 18 

percent macrohabitat generalists (fig. 19). Fish in the 

Ipswich target fish community had a population 

consisting of 49 percent fluvial specialists, 19 percent 

fluvial dependents, and 32 percent macrohabitat 

generalists. Although a target fish community for the 

Usquepaug–Queen River has not yet been developed, 

comparisons to the Quinebaug and Ipswich target fish 

communities indicate that, for the sites analyzed in this 

report, the species composition of the mainstem 

Usquepaug–Queen River appears to have percentages 

of fluvial species that are near the ranges that could be 

expected. 

Table 7. Scientific names and habitat-use classifications of fish in the 

Usquepaug–Queen River Basin, Rhode Island

[Macrohabitat: FD, fluvial dependent; FS, fluvial specialist; MG, 

macrohabitat generalist]

Common name Genus Species Macrohabitat

American Eel Anguilla rostrata MG

Atlantic Salmon Salmo salar FS

Banded Sunfish Enneacanthus obesus MG

Blacknose Dace Rhinichthys atratulus FS

Bluegill Lepomis macrochirus MG

Bridle Shiner Notropis bifrenatus MG

Brook Trout Salvelinus fontinalis FS

Brown Bullhead Ameiurus nebulosus MG

Chain Pickerel Esox niger MG

Common Shiner Luxilus cornutus FD

Creek Chubsucker Erimyzon oblongus FS

Fallfish Semotilus corporalis FS

Golden Shiner Notemigonus crysoleucas MG

Largemouth Bass Micropterus salmoides MG

Pumpkinseed Lepomis gibbosus MG

Redfin Pickerel Esox americanus MG

Swamp Darter Etheostoma fusiforme MG

Tesselated Darter Etheostoma olmstedi FS

White Sucker Catostomus commersoni FD

Yellow Perch Perca flavescens MG

A. Usquepaug-Queen River

mainstem sites, 1998–2000

B. Usquepaug-Queen River

tributary sites, 1998–2000

51% 39%

10%

9%

6%

85%

EXPLANATION

MACROHABITAT GENERALIST

FLUVIAL DEPENDENT

FLUVIAL SPECIALIST

% PERCENT OF TOTAL

Figure 18. Fish species habitat-use classifications for the Usquepaug–

Queen River, Rhode Island: (A) mainstem sites, 1998–2000, and 

(B) tributary sites, 1998–2000.
Streamflow Requirements for Habitat Protection 37

STREAMFLOW REQUIREMENTS FOR

HABITAT PROTECTION

One diagnostic and four standard-setting methods 

were used to develop summer streamflow requirements for 

the Usquepaug–Queen River. The RVA, Tennant, and ABF 

methods require streamflow data from gaged sites, whereas 

the Wetted-Perimeter and R2Cross methods require surveys 

of channel cross sections and water-surface slopes at critical 

riffle sites, and simulation of stage, discharge, wettedperimeter, velocity, depth, and other hydraulic criteria used 

for determination of streamflow requirements.

Streamflow requirements were calculated by means 

of the RVA, Tennant, and ABF methods on the basis of flow 

records from the Usquepaug River at Usquepaug gaging 

station (01117420). Comparisons were made to streamflow 

requirements determined from the Wood River near Arcadia 

(01117800) and Beaver River near Usquepaug (01117468) 

gaging stations, and to other gaging stations in southern 

New England. Streamflow requirements were calculated 

by the Wetted-Perimeter and R2Cross methods from field 

measurements at seven riffles (table 5). Three of these sites 

are on the Usquepaug–Queen River mainstem, and four are 

on the Fisherville Brook and Locke Brook tributaries and in 

the Queen River headwaters. The mainstem sites are located 

on the Usquepaug River near Laurel Lanes Golf Course in 

South Kingstown (U2), the Usquepaug River near Route 138 

in South Kingstown (U1), and the Queen River near Dawley 

Road in Exeter (Q5). The tributary sites are located on the 

Queen River at William Reynolds Road (Q3), Fisherville 

Brook near Liberty Church Road (F2), Fisherville Brook 

near Pardon Joslin Road (F1), and Locke Brook near 

Mail Road in Exeter (F1). These sites were chosen for 

determination of streamflow requirements for habitat 

protection because of their sensitivity to low flows. During 

declining flows, these riffles are among the first reaches to 

show habitat losses.

Site descriptions and data used for development and 

calibration of the WinXS Pro and HEC-RAS models are 

given in Appendix 1, along with the hydraulic criteria (stage, 

average depth, average velocity, and percent bank-full wetted 

perimeter) determined by the models for a range of 

discharges. 

A. Quinebaug River

18%

27% 55%

B. Ipswich River

49%

32%

19%

EXPLANATION

MACROHABITAT GENERALIST

FLUVIAL DEPENDENT

FLUVIAL SPECIALIST

% PERCENT OF TOTAL

Figure 19. Target fish communities for the: (A) Quinebaug 

River, Massachusetts, and (B) Ipswich River, 

Massachusetts.
38 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Indicators of Hydrologic Alteration and 

Range of Variability Approach

Results of the IHA analysis from the Usquepaug 

River near Usquepaug gaging station (01117420) 

showing mean-monthly discharge for the period 

1976–2000, normalized to drainage area, are shown in 

figure 20. The pattern of mean-monthly discharge 

shows flows generally increasing from October 

through March or April. Mean monthly flows generally 

decline from March or April through September. The 

low-flow period extends from July through October, 

with the lowest monthly mean in September. 

Streamflows from the Usquepaug River near 

Usquepaug gaging station (01117420) were compared 

to streamflows from two nearby streamflow-gaging 

stations that also are in the Pawcatuck River Basin: 

Beaver River near Usquepaug, RI (01117468), and 

Wood River near Arcadia, RI (01117500). The 

drainage area of the Usquepaug River gage (36.1 mi2) 

is almost equal to the area for the Wood River gage 

(35.2 mi2), but is considerably larger than the area for 

the Beaver River gage (8.87 mi2). The Beaver and 

Wood Rivers have few water withdrawals upstream of 

the gaging stations and represent mostly unregulated 

conditions. Streamflows in the Usquepaug River are 

relatively unregulated in fall, winter, and spring.

OND J FMAMJ J AS

0

1

2

3

4

5

6

7

DISCHARGE, IN CUBIC FEET PER

SECOND PER SQUARE MILE

MONTH

90th percentile

10th percentile

75th percentile

25th percentile

Median

EXPLANATION

PERCENTILE DISTRIBUTION

Figure 20. Distribution of monthly mean flow, Usquepaug River near Usquepaug, Rhode Island, gaging station 

(01117420).
Streamflow Requirements for Habitat Protection 39

The range of variability in monthly mean 

streamflows, annual n-day low-flow statistics, and 

additional measures of flow used by the RVA as flowmanagement targets are given in tables 8, 9, and 10 

for the Usquepaug, Beaver, and Wood River gaging 

stations for the 25-year period from 1976–2000. 

Because of water withdrawals upstream of the 

Usquepaug gaging station between May and October, 

monthly means for the summer months, annual n-day 

low flows, and other low-flow statistics are lower than 

they would be were there no withdrawals. Nonetheless, 

these streamflow statistics can be useful indicators of 

the magnitude of streamflows recommended as flowmanagement targets by the RVA method. Once the 

HSPF model under development for the Usquepaug–

Queen Basin is complete, streamflows representing nowithdrawal conditions in the Usquepaug–Queen River 

can be simulated, and the RVA streamflow statistics can 

be recalculated. The recalculated mean monthly flows 

for the summer months and low-flow statistics for the 

Usquepaug gaging station would be expected to be 

higher than those calculated from current conditions. 

Maintenance of streamflow variability 

throughout the year and between years is important for 

a healthy ecosystem (Poff and others, 1998; Hill and 

others, 1991). Water withdrawals or regulation that 

cause streamflows to be maintained at a minimum level 

over an extended period of time are detrimental to a 

healthy ecosystem (Instream Flow Council, 2002). The 

RVA recommends maintaining flows within a range of 

streamflow that is similar to the natural flow regime of 

the stream. The target range is defined by the 25th to 

75th percentiles for monthly mean flows, and for 

several ecologically relevant flow statistics such as the 

1-, 3-, 7-, 30-, and 90-day annual low-flows (n-day lowflow periods), the number of days that the daily 

discharge is below the 25th percentile, and the number 

of days of zero flow. In the summer months, the 

streamflow at the lower limit of this target range (25th 

percentile) for some of these flow statistics may be 

lower than the streamflow requirements for habitat 

protection determined by standard-setting methods. 

The RVA does not recommend maintaining flows 

exclusively at or near the level of the lower percentile, 

however, and restricts the magnitude, timing, 

frequency, and duration of low flows by requiring 

streamflow to be within the 25th- to 75th-percentile 

range for each of 33 flow statisitics. The ability 

to maintain streamflows within the RVA flowmanagement target ranges would require active and 

coordinated management controls, particularly during 

late summer when flows are naturally low.

Table 8. Hydrologic data for the 1976 to 2000 period for the gaging station on the Usquepaug River near Usquepaug (01117420), 

Rhode Island

Period or condition

Percentile

10th 25th 50th 75th 90th (75-25)/50

Magnitude of monthly mean discharge (cubic feet per second)

October 14.3 21.5 28.8 50.0 69.8 1.0

November 24.0 28.8 57.3 80.7 117.3 .9

December 28.9 54.5 69.4 100.9 190.4 .7

January 45.6 60.7 96.7 128.5 190.1 .7

February 49.0 78.0 123.1 142.0 164.2 .5

March 70.7 94.0 116.4 165.6 230.4 .6

April 67.6 81.3 126.8 183.3 207.7 .8

May 50.3 68.8 88.3 119.2 164.0 .6

June 31.7 36.7 48.4 87.0 168.3 1.0

July 16.2 19.6 29.9 43.4 68.3 .8

August 12.0 16.0 28.4 43.4 55.5 1.0

September 11.4 14.1 21.7 39.1 44.8 1.2
40 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Magnitude and duration of annual discharge conditions 

(cubic feet per second)

1-day minimum 3.5 5.2 11.0 14.0 18.4 0.8

3-day minimum 3.9 5.4 11.7 14.8 19.2 .8

7-day minimum 5.0 6.9 12.6 16.4 20.8 .8

30-day minimum 7.9 10.5 17.1 20.4 26.2 .6

90-day minimum 13.2 16.3 20.7 33.6 38.8 .8

1-day maximum 223.6 270.0 373.0 564.5 664.6 .8

3-day maximum 195.9 227.8 321.3 484.3 597.7 .8

7-day maximum 150.7 194.6 255.7 365.6 455.9 .7

30-day maximum 102.8 144.6 185.3 246.6 278.0 .6

90- day maximum 96.0 111.6 145.5 164.0 209.3 .4

 Zero discharge days 0 0 0 0 0 0

7-day minimum/mean annual 

discharge

.1 .1 .1 .2 .3 1.0

Timing of annual discharge extremes (Julian day)

Date of minimum 1-day discharge 205.6 225.5 254.0 275.0 275.8 0.1

Date of maximum 1-day discharge 10.8 28.5 83.0 111.5 156.0 .2

Frequency and duration of high and low pulses 

Times that daily discharge is less 

than the 25th percentile of daily 

discharge (count)

3.0 5.0 8.0 9.5 11.4 0.6

Days that daily discharge is less than 

the 25th percentile

4.7 6.0 10.0 14.9 20.1 .9

Times that daily discharge is greater 

than the 75th percentile of daily 

discharge (count)

3.0 5.0 9.0 11.0 13.0 .7

Days that daily discharge is greater 

than the 75th percentile

3.2 5.8 11.0 14.0 26.9 .7

Rate and frequency of hydrograph changes

Mean of all positive differences 

between consecutive daily 

discharges (rise rate) 

12.4 15.9 17.7 24.9 31.2 0.5

Mean of all negative differences 

between consecutive daily 

discharges (fall rate)

-13.2 -10.6 -7.9 -7.1 -5.8 -.4

Number of reversals 86.6 92.5 97.0 102.0 104.2 .1

Table 8. Hydrologic data for the 1976 to 2000 period for the gaging station on the Usquepaug River near Usquepaug (01117420), 

Rhode Island—Continued

Period or condition

Percentile

10th 25th 50th 75th 90th (75-25)/50
Streamflow Requirements for Habitat Protection 41

Table 9. Hydrologic data for the 1976 to 2000 period for the gaging station Beaver River near Usquepaug (01117468), Rhode Island

Period or condition

Percentile

10th 25th 50th 75th 90th (75-25)/50

Magnitude of monthly mean discharge (cubic feet per second)

October 3.29 4.7 6.72 12.38 19.16 1.14

November 6.01 7 13.95 24.08 34.62 1.22

December 7.33 13.66 20.11 30.48 50.68 .84

January 11.17 17.56 27.16 33.94 50.41 .6

February 12.78 20.96 31.82 37.93 43.29 .53

March 22.45 26.52 32.94 44.37 57.37 .54

April 20.05 23.55 36.9 46.02 55.77 .61

May 15.25 19.74 24.84 35.37 45.84 .63

June 9.45 11.55 14.53 25.95 45.99 .99

July 4.7 5.8 8.68 12.34 22.03 .75

August 2.72 4.32 7.38 11.43 14.64 .96

September 2.82 3.63 5.92 9.18 11.67 .94

Magnitude and duration of annual discharge conditions 

(cubic feet per second)

1-day minimum 1.36 1.8 2.7 3.1 4.44 0.48

3-day minimum 1.42 1.8 2.7 3.23 4.51 .53

7-day minimum 1.59 2.09 2.91 3.91 4.84 .63

30-day minimum 2.07 2.62 4.23 5.38 6.73 .65

90-day minimum 3.23 4.44 5.82 8.71 10.46 .73

1-day maximum 65.6 77 109 149 236.2 .66

3-day maximum 53.47 67.17 90.67 121.67 178.4 .6

7-day maximum 41.14 51.57 71 93.14 136.17 .59

30-day maximum 29.38 38.73 49 63.1 81.34 .5

90- day maximum 26.09 31.32 39.36 45.12 52.68 .35

 Zero discharge days 0 0 0 0 0 0

7-day minimum/mean annual 

discharge

.08 .1 .13 .2 .28 .79

Timing of annual discharge extremes (Julian day)

Date of minimum 1-day discharge 220.6 247 267 275 279.8 0.08

Date of maximum 1-day discharge 327.2 24.5 71 110.5 155 .23

Frequency and duration of high and low pulses 

Times that daily discharge is less 

than the 25th percentile of daily 

discharge (count)

2.8 6 7 10.5 11.8 0.64

Days that daily discharge is less than 

the 25th percentile

3.79 5.97 8.88 14.58 19.39 .97

Times that daily discharge is greater 

than the 75th percentile of daily 

discharge (count)

4 7 10 12 17 .5

Days that daily discharge is greater 

than the 75th percentile

2.48 4.97 9.5 11.63 18.56 .7
42 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Rate and frequency of hydrograph change

Mean of all positive differences 

between consecutive daily 

discharges (rise rate) 

5 5.89 7.12 8.14 11.53 0.32

Mean of all negative differences 

between consecutive daily 

discharges (fall rate)

-4 -3.11 -2.68 -2.27 -1.84 -.31

Number of reversals 74.6 84 92 102 110.4 .2

Table 9. Hydrologic data for the 1976 to 2000 period for the gaging station Beaver River near Usquepaug (01117468), Rhode Island—Continued

Period or condition

Percentile

10th 25th 50th 75th 90th (75-25)/50

Table 10. Hydrologic data for the 1976 to 2000 period for the gaging station Wood River near Arcadia (01117800), Rhode Island

Period or condition

Percentile

10th 25th 50th 75th 90th (75-25)/50

Magnitude of monthly mean discharge (cubic feet per second)

October 13.1 19.33 29.53 57.96 87.5 1.31

November 29.18 37.37 62.87 95.81 118.73 .93

December 38.4 56.93 78.44 123.12 194.08 .84

January 46.94 66.7 107.76 123.09 196.53 .52

February 56.48 83.45 112.14 145.11 154.84 .55

March 79.94 99.8 129.02 172.19 208.16 .56

April 80.5 85.82 129.97 156.75 224.38 .55

May 55.06 68.4 86.71 118.02 145.65 .57

June 31.1 33.48 45.55 69.14 128.28 .78

July 12.92 17.77 27.81 36.72 60.35 .68

August 9.87 17.43 25.44 50.68 63.08 1.31

September 9.82 16.69 21.77 32.59 44.8 .73

Magnitude and duration of annual discharge conditions 

(cubic feet per second)

1-day minimum 5.05 6.93 8.95 13 16.5 0.68

3-day minimum 5.38 7.49 9.27 14.08 17 .71

7-day minimum 5.73 8.29 10.76 16.39 18.29 .75

30-day minimum 7.16 10.92 14.74 19.71 24.8 .6

90-day minimum 11.67 16.08 25.43 30.85 42.77 .58

1-day maximum 253.5 295 378.5 538.25 719.5 .64

3-day maximum 213.17 258.58 318.17 462.33 598 .64

7-day maximum 162.71 205.61 242.14 375.5 463.57 .7

30-day maximum 119.38 135.43 187.85 226.45 296 .48

90- day maximum 96.22 116.29 147.57 163.29 195.97 .32

 Zero discharge days 0 0 0 0 0 0

7-day minimum/mean annual 

discharge

.08 .1 .16 .19 .24 .61
Streamflow Requirements for Habitat Protection 43

Timing of annual discharge extremes (Julian day)

Date of minimum 1-day discharge 209 224.75 252 273.5 284 0.13

Date of maximum 1-day discharge 351 24.75 70.5 104 124.5 .22

Frequency and duration of high and low pulses 

Times that daily discharge is less 

than the 25th percentile of daily 

discharge (count)

4.5 5 7.5 9 11 0.53

Days that daily discharge is less than 

the 25th percentile

5.61 7.09 10.86 14.94 23.53 .72

Times that daily discharge is greater 

than the 75th percentile of daily 

discharge (count)

3.5 6.25 9.5 12.75 15.5 .68

Days that daily discharge is greater 

than the 75th percentile

3.26 6.19 9.92 13.9 17.94 .78

Rate and frequency of hydrograph changes

Mean of all positive differences 

between consecutive daily 

discharges (rise rate) 

12.44 17.89 21.11 31.34 36.12 .64

Mean of all negative differences 

between consecutive daily 

discharges (fall rate)

-13.02 -10.67 -7.75 -6.83 -4.96 -.5

Number of reversals 82 88 96.5 102 106.5 .15

Table 10. Hydrologic data for the 1976 to 2000 period for the gaging station Wood River near Arcadia (01117800), Rhode Island—Continued

Period or condition

Percentile

10th 25th 50th 75th 90th (75-25)/50

Tennant Method

Streamflow requirements were calculated 

by the Tennant method from streamflow data from 

the gaging station on the Usquepaug River near 

Usquepaug (01117420) for the period 1958–2000. 

The mean annual flow (QMA), the flow statistic used 

by the Tennant method, is 76.7 ft3/s at the Usquepaug 

gage (Socolow and others, 2000). Streamflow 

requirements determined by the Tennant method are 

given in table 11. The 40-, 30-, and 10-percent QMA

values for the Usquepaug River which represent good, 

fair, and poor habitat conditions according to Tennant 

(1976), normalized for drainage area, are 0.85, 0.64, 

and 0.21 ft3/s/mi2, respectively. The 25-percent QMA

value, which is used to determine summer streamflow 

requirements in the Canadian Atlantic Provinces 

(Dunbar and others, 1998), is 0.53 ft3/s/mi2. 

For comparison, Tennant streamflow 

requirements were also determined for 16 nearby 

gaging stations in Rhode Island, Connecticut, and 

Massachusetts with at least 20 years of good record. 

The average 40-, 30-, and 10-percent QMA values 

for these sites were very similar to those determined 

for the Usquepaug River and were 0.80, 0.60, and 

0.20 ft3/s/mi2, respectively. The 25-percent QMA used 

to set streamflow requirements in the Canadian 

Atlantic Provinces averaged 0.50 ft3/s/mi2 (table 12). 

The 40-, 30-, and 10-percent QMA Tennant streamflow 

requirements for the nearby Wood River were almost 

identical to those determined for the Usquepaug River 

and were 0.87, 0.65, and 0.22 ft3/s/mi2. The 40-, 30-, 

and 10-percent Tennant streamflow requirements for 

the nearby Beaver River were slightly higher and were 

0.96, 0.72, and 0.24 ft3/s/mi2, respectively. The latter 

two basins are generally considered to be unregulated. 
44 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Severe 

Table 11. Summer streamflow requirements determined by the Tennant 

method for the gaging station Usquepaug River near Usquepaug 

(01117420), Rhode Island

[QMA, mean annual flow; ft3/s, cubic feet per second; ft3/s/mi2, cubic feet 

per second per square mile; <, less than]

Aquatic-habitat

condition for

small streams

Percentage

of QMA, 

April–September

Streamflow 

requirements

ft3/s ft3/s/mi2

Flushing flows 200 153.4 4.25

Optimum range 60–100 46–76.7 1.28–2.13

Outstanding 60 46 1.28

Excellent 50 38.4 1.06

Good 40 30.7 0.85

Fair 30 23.0 0.64

Poor <10 <7.7 <0.21

Severe degradation <10 <7.7 <0.21

Table 12. Streamflow requirements determined by the Tennant Method for 16 gaging stations in southern New England

[QMA, Mean annual flow; ft3/s, cubic feet per second; ft3/s/mi2, cubic feet per second per square mile; mi2, square mile]

Gaging station

Drainage

area

(mi2)

QMA

(ft3/s)

Period

of record

(years)

QMA

(ft3/s/mi2)

0.4 QMA

(ft3/s/mi2)

0.3 QMA

(ft3/s/mi2)

0.25 QMA

(ft3/s/mi2)

0.1 QMA

(ft3/s/mi2)

Beaver River (01117468) 8.87 21.3 24 2.40 0.96 0.72 0.60 0.24

Wood River near Arcadia (01117800) 35.2 76.7 34 2.18 .87 .65 .54 .22

Wood River near Hope Valley 

(01118000)

72.4 156 58 2.15 .86 .65 .54 .22

Pendleton Hill Brook (01118300) 4.02 8.62 40 2.14 .86 .64 .54 .21

Chipuxet River (01117350) 9.99 21.3 27 2.13 .85 .64 .53 .21

Indian Head River (01105730) 30.3 63.1 33 2.08 .83 .62 .52 .21

Hunt River (01117000) 22.9 46.8 59 2.04 .82 .61 .51 .20

Old Swamp River (01105600) 4.5 9.18 33 2.04 .82 .61 .51 .20

Pawcatuck River at Wood R. Jct 

(01117500)

100 196 58 1.96 .78 .59 .49 .20

Pawcatuck River at Westerly (01118500) 295 577 58 1.96 .78 .59 .49 .20

Branch River (01111500) 91.2 175 59 1.92 .77 .58 .48 .19

Little River (01123000) 30 57 47 1.90 .76 .57 .48 .19

Salmon River (01193500) 100 186 70 1.86 .74 .56 .47 .19

Mount Hope River (01121000) 28.6 52.3 58 1.83 .73 .55 .46 .18

Moshassuck River (01114000) 23.1 40.6 36 1.76 .70 .53 .44 .18

Broad Brook (01184490) 15.5 24.7 38 1.59 .64 .48 .40 .16

Averages 2.00 0.80 0.60 0.50 0.20
Streamflow Requirements for Habitat Protection 45

New England Aquatic-Base-Flow 

Method

Streamflow requirements for the Usquepaug 

River obtained with the ABF method stipulate 

default streamflows of 0.5 ft3/s/mi2 in summer, 

1.0 ft3/s/mi2 in fall and winter, and 4.0 ft3/s/mi2 in 

spring. The ABF method requires these default 

streamflows to be used rather than streamflows 

determined from the ABF median of monthly-mean 

flows for rivers that are regulated and have drainage 

areas of less than 50 mi2. These drainage-area criteria 

and free-flowing requirements were intended to 

provide consistent resource-protective (conservative ) 

results (Lang, 1999). However, even with current levels 

of water withdrawals, the summer streamflows in the 

Usquepaug River are frequently greater than the 

0.5 ft3/s/mi2 ABF default summer-streamflow 

requirement. The median of monthly mean flows for 

August for the Usquepaug River near Usquepaug 

(01117420) gaging station was 28.35 ft3/s, or 0.79 

ft3/s/mi2, for the 1976–2000 period. The high base 

flows in the Usquepaug River are likely caused by large 

amounts of ground-water discharge (Dickerman, 1997) 

from sand and gravel aquifers in the Usquepaug–Queen 

River Basin. 

For purposes of comparison, the medians of 

monthly-mean flows for August were also calculated 

for nearby gaging stations on the Wood and Beaver 

Rivers. These gaging stations were selected because 

they are within the same drainage basin (Pawcatuck 

River Basin), and have minimal to no water 

withdrawals above the gage. Normalized for drainage 

area, the August median streamflow for the 

Usquepaug–Queen River, (0.79 ft3/s/mi2) is similar in 

magnitude to the Beaver River (0.83 ft3/s/mi2) and 

Wood River (0.72 ft3/s/mi2). The Wood River likely 

has a lower median of monthly mean flows for August, 

normalized for drainage area, than the Usquepaug 

River because it has a smaller area of sand and gravel 

as a percentage of drainage area (about 24 percent) 

than the Usquepaug–Queen River Basin (about 35 

percent) (Cervione and others, 1993).

Monthly mean flows for August at the 

Usquepaug River stream-gaging station were also 

compared to those at nearby stream gages in Rhode 

Island, Connecticut, and Massachusetts. A plot of the 

distribution of August mean flow for the 1976–2000 

period for 10 southern New England gaging stations 

(fig. 21) indicates that, even with water withdrawals, 

the Usquepaug River has one of the highest values for 

the median of monthly mean flow for August in 

comparison to nearby streams. Consequently, the 

Usquepaug–Queen River may require higher 

streamflow requirements than nearby rivers to protect 

the habitat provided by its higher baseflows.

Wetted-Perimeter Method

Streamflow requirements were determined by 

the Wetted-Perimeter method for seven riffle sites on 

the Usquepaug–Queen River (table 13). Wetted–

Perimeter streamflow requirements, normalized for 

drainage area, ranged from 0.21 to 0.66 ft3/s/mi2. The 

median streamflow requirement was 0.41 ft3/s/mi2. 

Because channel alterations may change the 

streamflow requirements determined by the WettedPerimeter method, an alternative streamflow 

requirement for habitat protection can be determined 

by averaging only the Wetted-Perimeter results from 

unaltered sites. The Wetted-Perimeter streamflow 

requirements for the three most natural riffle sites were 

0.41 ft3/s/mi2 for the Usquepaug River at Laurel Lanes, 

0.50 ft3/s/mi2 for Fisherville Brook near Liberty 

Church Road, and 0.33 ft3/s/mi2 for Fisherville Brook 

near Pardon Joslin Road. The median of the WettedPerimeter streamflow requirements for these three sites 

is also 0.41 ft3/s/mi2. 
46 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

Streamflow requirements determined by the 

Wetted-Perimeter method often correspond to a water 

level that has just begun to rise up the stream banks (a 

fully-wetted channel bed). To reduce the subjectivity 

that may occur in those cases where the point of 

maximum curvature in the wetted-perimeter-todischarge relation was difficult to determine, 

streamflow requirements were determined from breaks 

in the slope of the wetted-perimeter-discharge curves 

that corresponded to the point where the water level 

reaches the bottom of the stream bank, as determined 

from toe-of-bank elevations identified during site 

surveys. Because of the channel shape at some of the 

study sites, streamflow requirements identified by the 

Wetted-Perimeter method may provide only a minimal 

amount of habitat in some of the riffles. Those sites that 

have flat-bottomed, rectangular or trapezoidal channel 

shapes, such as the Usquepaug River at Route 138, 

Queen River at Dawley Road, and Queen River near 

William Reynolds Road, often have a fully-wetted 

Beaver River, RI

Usquepaug River, RI

Moshassuck River, RI

Hunt River, RI

Old Swamp River, MA

Indian Head River, MA

Wood River, RI

Branch River, RI

Little River, CT

Mount Hope River, CT

Pendleton Brook, CT

0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

DISCHARGE, IN CUBIC FEET PER 

SECOND PER SQUARE MILE

90th percentile

10th percentile

75th percentile

25th percentile

Median

EXPLANATION

PERCENTILE DISTRIBUTION

SITE LOCATION

Figure 21. Distribution of monthly mean flow for August for 11 gaging stations in southern New England.
Streamflow Requirements for Habitat Protection 47

channel bed at very low discharges. Flows estimated by 

the Wetted-Perimeter method for these riffles may not 

necessarily provide water depths at the stream margins 

or within portions of the riffle that are sufficient for 

these areas to provide good habitat conditions for fish. 

R2Cross Method

Streamflow requirements were determined by the 

R2Cross method for seven riffle sites on the 

Usquepaug–Queen River (table 13). R2Cross 

streamflow requirements, normalized for drainage area, 

ranged from 0.28 to 1.86 ft3/s/mi2 (table 13). The 

median streamflow requirement was 0.72 ft3/s/mi2. 

Alterations to channel width can affect the 

streamflow requirements determined by the R2Cross 

method. Streamflow requirements may be higher in 

channels that have been widened, and lower in 

channels that are narrower than the natural channel. 

Because of the scarcity of suitable, unaltered riffle sites 

on the Usquepaug–Queen River, some of the study sites 

were altered sites. Efforts were made to locate cross 

sections at the least altered locations within these 

riffles. The study sites at the Usquepaug River near 

Route 138, Queen River near William Reynolds Road,

Table 13. Streamflow requirements computed by Wetted-Perimeter and 

R2Cross methods for seven riffle study sites, Usquepaug–Queen River, 

Rhode Island

[USGS, U.S. Geological Survey; ft3/s/mi2, cubic feet per second per square 

mile]

USGS 

habitat 

site 

identifier

River and reach

Streamflow 

requirement 

Wetted

perimeter

(ft3/s/mi2)

R2Cross

(ft3/s/mi2)

U2 Usquepaug River near Laurel Lane 0.41 0.28

U1 Usquepaug River at Route 138 .25 .59

Q5 Queen River near Dawley Road .21 1.82

Q3 Queen River near William 

Reynolds Road

.64 1.86

F2 Fisherville Brook at Liberty 

Church Road

.50 .72

F1 Fisherville Brook near Pardon 

Joslin Road

.33 .58

L1 Locke Brook at Mail Road .66 1.31

Mean .43 1.02

Median .41 .72

and Locke Brook near Mail Road sites appear to 

have altered channels that may have affected the 

results of the R2Cross analysis. The study site near 

Route 138 has riprap on the right bank and may have a 

straightened channel because of the historic operation 

of mills at the site. Consequently, the stream channel at 

this site may be not be able to fully adjust its width 

naturally. The riffles at the Queen River near William 

Reynolds Road, and Locke Brook near Mail Road sites 

are immediately downstream of road crossings. The 

channels at these sites may have been widened relative 

to their unaltered channel width, and likely contain 

deposits of coarse-grained substrate that were eroded 

from scour holes downstream of the bridges during 

high flow. R2Cross streamflow requirements calculated 

for these sites may be higher than streamflow 

requirements calculated for unaltered channels. 

Because channel alterations may change the 

streamflow requirements determined by the R2Cross 

method, an alternative streamflow requirement for 

habitat protection can be determined by averaging only 

the R2Cross results from unaltered sites. The R2Cross 

streamflow requirements for the three most natural 

riffle sites were 0.28 ft3/s/mi2 for the Usquepaug River 

at Laurel Lanes, 0.72 ft3/s/mi2 for Fisherville Brook 

near Liberty Church Road, and 0.58 ft3/s/mi2 for 

Fisherville Brook near Pardon Joslin Road. The median 

of the R2Cross streamflow requirements for these three 

sites is 0.58 ft3/s/mi2.

Other sites that may not meet the criteria for 

application of the R2Cross method include riffles 

that have marginal water-surface slopes for application 

of Manning's equation and riffles that are submerged at 

low to moderate flows by backwater from downstream 

controls. The high R2Cross streamflow requirements 

at the Queen River near Dawley Road may be 

attributed to the fact that the gradient of the riffle is 

near or below the recommended limits for application 

of Manning's equation. The riffle becomes a run at low 

to moderate flows and requires a high discharge to 

meet the R2Cross 1 ft/s mean-velocity criterion. 

Backwater conditions created by vegetation in the 

channel may also have affected the water levels in the 

riffle that were used for calibration of the flow model 

for this site. The study sites on the Usquepaug River 

near Laurel Lane and Fisherville Brook near Pardon 

Joslin Road also may become affected by backwater 

conditions at moderate to high flows, however; these 

sites appear to have sufficient gradient to remain riffles 

at the low flows identified as streamflow requirements.
48 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

COMPARISON OF STREAMFLOW

REQUIREMENTS AND METHODS

Streamflow requirements for habitat protection 

were computed by the Tennant, ABF, and RVA 

methods on the basis of flow records from the 

Usquepaug River near Usquepaug stream gaging 

station (01117420) for the period 1976–2000. Flows at 

this gaging station are affected by upstream water 

withdrawals. Streamflow requirements determined 

from these records would likely be lower than those 

determined from natural streamflows or simulated 

streamflows without withdrawals. These preliminary 

values are useful, however, to indicate the magnitude of 

streamflow requirements. Once natural streamflows are 

simulated by the USGS using an HSPF model (G.C. 

Bent, U.S. Geological Survey, written commun., 2002), 

the Tennant, ABF, and RVA streamflow requirements 

can be recalculated for the Usquepaug gaging station 

and also can be computed for other locations in the 

basin such as the riffle sites where the WettedPerimeter and R2Cross methods were applied. 

The streamflow requirements determined by the 

Tennant method for the 40-percent and 30-percent 

QMA, (considered by Tennant to provide good and 

fair summer-habitat conditions) were 0.85 and 

0.64 ft3/s/mi2, respectively. The 0.79 ft3/s/mi2 

streamflow requirement calculated on the basis of the 

ABF median of monthly mean flows is between the 

0.40 and 0.30 QMA Tennant streamflow requirements, 

and thus identifies fair to good habitat conditions, 

according to Tennant (1976).

One advantage of the Tennant method is 

that it is is less sensitive to regulation than other 

methods, because its value is a percentage of a mean 

annual flow statistic that is heavily weighted to 

high flows that are least affected by summer 

withdrawals. In contrast, the ABF method based 

on the median of monthly mean flows for August is 

sensitive to regulation, because the streamflow 

depletion caused by summer water withdrawals is a 

large percentage of August streamflow. Despite 

summer water withdrawals, the median of monthly 

mean flow for August for the Usquepaug gaging 

station was higher than that determined from nine 

nearby gaging stations with virtually unaltered flow 

(fig. 21). This indicates that high summer streamflow 

requirements may be needed in the Usquepaug–Queen 

River to maintain summer low flows within the ranges 

of those that would have occurred naturally. 

The R2Cross and Wetted-Perimeter methods 

require collection of site-specific physical and 

hydraulic data, such as channel geometry, average 

velocity, and mean depth at riffle sites. An advantage 

of the R2Cross and Wetted-Perimeter methods is that 

they are based on field observations and do not require 

data from a streamflow-gaging station, so the flow 

values obtained by these methods can be applied in 

hydrologically disturbed drainage basins and at either 

gaged or ungaged sites. During the site-selection 

process, however, care must be taken to select 

appropriate sites. Well defined riffle habitats that 

extend across the entire channel and that maintain 

hydraulic control over a range of low to moderate 

flows can be difficult to locate, and may be difficult 

to identify at some streamflows. Furthermore, 

differences in channel geometry among riffles can 

create variability in resulting streamflow requirements. 

In particular, alterations to channels can have a direct 

effect on the streamflow recommendations produced 

by these methods. Variability in the streamflow 

requirements calculated by the Wetted-Perimeter and 

R2Cross methods does not necessarily indicate 

inaccuracies in these methods (Annear and Conder, 

1984). The streamflow requirements determined by the 

Wetted-Perimeter and R2Cross methods may differ 

between natural and altered channels, depending 

on the degree and type of alteration to the channel. 

Consequently, streamflow requirements determined 

for natural riffle sites may not be sufficient to protect 

habitat at sites in a widened channel, and flow 

requirements estimated at sites with a narrowed 

channel may not provide sufficient flows for habitat 

protection in unaltered stream reaches. The WettedPerimeter and R2Cross methods, therefore, should not 

be applied indiscriminately.

Summer streamflow requirements for habitat 

protection were computed for seven riffle sites by 

means of the Wetted-Perimeter and R2Cross methods 

(table 13). The median Wetted-Perimeter and R2Cross 

streamflow requirements were 0.41 ft3/s/mi2 and 

0.72 ft3/s/mi2, respectively. If only the unaltered sites 

are considered, the median Wetted-Perimeter and 

R2Cross streamflow requirements are 0.41 and 

0.58 ft3/s/mi2, respectively. R2Cross streamflow 

requirements were higher than Wetted-Perimeter 

streamflow requirements for all but one of the sites. 

R2Cross streamflow requirements tend to be higher 

because the method, as applied in this report, requires 

depth, velocity, and wetted-perimeter criteria to be met, 
Comparison of Streamflow Requirements and Methods 49

whereas Wetted-Perimeter streamflow requirements 

require only that the streambed be wetted to the bottom 

of the bank. 

The streamflow requirements determined 

by the Wetted-Perimeter and R2Cross methods are 

compared in figure 22 to the distribution of monthly 

mean flows for the summer months for four gaging 

stations on streams with mostly unaltered flow for 

the 1976–2000 period: these stations include the 

Beaver River (01117468), Branch River (01111500), 

and Wood River (01117800) gaging stations in 

Rhode Island, and the Indian Head River (01105730) 

in Massachusetts. The R2Cross and Wetted-Perimeter 

streamflow requirements fall within the range of 

flows recommended by the RVA for July, August, 

and September, and are below the recommended 

monthly flow range for portions of June and October. 

Comparison of median streamflow requirements

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

R2Cross

Wetted Perimeter

90th percentile

10th percentile

75th percentile

25th percentile

Median

EXPLANATION

MONTH

JUNE JULY AUGUST SEPTEMBER OCTOBER

PERCENTILE DISTRIBUTION STREAMFLOW REQUIREMENTS

R2

WP

WP 0.41

R2 0.72

Figure 22. Distribution of median Wetted-Perimeter and R2Cross streamflow requirements for seven riffle sites on the 

Usquepaug–Queen River and the average distribution of the monthly mean flow during summer for the Beaver River (01117468), 

Branch River (01111500), and Wood River (01117800) gaging stations, Rhode Island, and the Indian Head River (01105730), 

Massachusetts. 

DISCHARGE, IN CUBIC FEET 

PER SECOND PER SQUARE MILE
50 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

determined by the Wetted-Perimeter and R2Cross 

methods to those determined by the Tennant method 

indicate that R2Cross streamflow requirements would 

provide habitat conditions that were fair to good and 

Wetted-Perimeter streamflow requirements would 

provide habitat conditions that were poor to fair when 

definitions for habitat quality identified by Tennant 

(1976) are used. 

The streamflow requirements for habitat 

protection, determined from the median WettedPerimeter and R2Cross results from unaltered 

sites, were 0.41 and 0.58 ft3/s/mi2, respectively. 

The summer streamflow requirements determined 

for the Usquepaug–Queen River by applying the 

30-percent QMA Tennant method and the ABF 

method based on the median of monthly mean 

flows for August to records from the Usquepaug 

gaging station (01117420), were 0.64 ft3/s/mi2 and 

0.79 ft3/s/mi2, respectively. Averaging the results of 

these four methods results in a summer streamflow 

requirement for habitat protection, to one significant 

figure, of about 0.6 ft3/s/mi2 for the Usquepaug–Queen 

River. A streamflow requirement of about 0.6 ft3/s/mi2 

is within the range of RVA flow-management targets 

for the months of July, August, and September, as 

determined for the Usquepaug gaging station and 

four nearby gaging stations with relatively unaltered 

flow. A streamflow of 0.6 ft3/s/mi2 will prevent the 

Usquepaug–Queen River from becoming segmented, 

and will provide habitat not only in the seven study 

riffles, but also throughout the basin. A summer 

streamflow requirement recalculated on the basis 

of natural flows simulated by the HSPF model, in 

combination with a varied flow regime identified 

by the RVA for the remainder of the year, will 

sustain fluvial fish communities and protect the 

stream integrity and natural ecosystem functions of 

unimpounded reaches of the Usquepaug–Queen River.

Standard-setting methods identify seasonal 

streamflow requirements that must sustain fish 

communities not only through the low-flow part 

of the summer (mid-July to mid-September), but also 

through the early (mid-June to mid-July) and late (midSeptember to mid-October) parts of the summer and 

early fall when flows are generally higher. Although 

standard-setting streamflow requirements identify 

flows that provide habitat protection during the 

low-flow part of the summer, it is important to 

recognize that flows will naturally fall below these 

minimum streamflow requirements for some days 

during the low-flow period in late summer (fig. 22). 

Because of the natural variability of streamflow, 

the period of time flows remain below streamflow 

requirements can vary from year to year. For example, 

records for the Usquepaug River gaging station 

(01117420) were screened to select years that had dry, 

normal, and wet summers (fig. 23). Dry, normal, and 

wet summers were defined on the basis of having 90-

day minimum flows close to the 25th, 50th, and 75th 

percentiles for the 90-day minimum flow between 

1976–2000, respectively. In a dry summer, flows could 

fall below a seasonal streamflow requirement of about 

0.6 ft3/s/mi2 for several months, including much of 

July, August, and September (fig. 23A). In a normal 

summer, flows could fall below a seasonal streamflow 

requirement of about 0.6 ft3/s/mi2 for several weeks 

each month, including most periods of base flow 

during July, August, and September (fig. 23B). In a wet 

year, flows could fall below a seasonal streamflow 

requirement of about 0.6 ft3/s/mi2 for several weeks 

(fig. 23C), especially during periods of base flow 

during late summer.

A flow-duration curve was determined for the 

Usquepaug River near Usquepaug stream-gaging 

station (fig. 24). This curve is a cumulative frequency 

curve that shows the percentage of time during which 

specified discharges were equaled or exceeded for an 

average year for the period of record. It also shows the 

integrated effect of various factors that affect runoff, 

such as climate, topography, and geology (Zappia and 

Hayes, 1998). If the discharge on which the flowduration curve is based represents the long-term flow 

conditions of a stream, the curve may be used to 

estimate the percentage of time specified discharges 

will be equaled or exceeded in the future (Searcy, 

1959). For example, the daily mean flow of 76.8 ft3/s is 

equaled or exceeded about 39 percent of the time and a 

discharge of 59.4 ft3/s is exceeded about 50 percent of 

the time (fig. 3). A streamflow requirement of 21.7 

(0.6 ft3/s/mi2) would be equaled or exceeded about 85 

percent of the time. The 55 days during which flows 

may be below the streamflow requirement would not 

necessarily all occur in the summer, but could occur at 

any time during an average year.
Comparison of Streamflow Requirements and Methods 51

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

R2Cross streamflow requirement

Wetted-Perimeter 

streamflow requirement

Daily mean flow, water year 1996

Daily mean flow, water year 2000

MAY JUNE JULY AUGUST SEPTEMBER

WP 0.41

R2 0.72

WP 0.41

R2 0.72

WP 0.41

R2 0.72

MONTH

DISCHARGE, IN CUBIC FEET PER SECOND PER SQUARE MILE 

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

R2Cross streamflow requirement

Wetted-Perimeter streamflow requirement

Daily mean flow, water year 1988

Daily mean flow, water year 1978

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

R2Cross streamflow requirement

Wetted-Perimeter streamflow requirement

Daily mean flow, water year 1999

Daily mean flow, water year 1994

A. Dry Years

B. Normal Years

C. Wet Years

Figure 23. Median Wetted-Perimeter and R2Cross streamflow requirements, and 

daily mean streamflows at the Usquepaug River gaging station (01117420), Rhode 

Island, between May and September during dry, normal, and wet years: (A) dry 

years, 1994 and 1999, (B) normal years, 1978 and 1988, and (C) wet years, 1996 and 

2000.
52 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

SUGGESTIONS FOR FURTHER

STUDY

A determination of an overall streamflow 

requirement for the Usquepaug–Queen River, as 

determined by the Wetted-Perimeter and R2Cross 

methods, would be more robust if a greater number 

of riffle sites were included in the analysis. The 

application of Wetted-Perimeter and R2Cross methods, 

however, is limited by the availability of unaltered riffle 

sites that have appropriate channel geometry for 

application of hydraulic models. Although there are 

additional riffles on tributaries that would be suitable 

for analysis, there are few additional riffle sites on the 

mainstem Usquepaug–Queen River where these 

methods could be applied. The inclusion of more 

tributary sites could bias the results of the overall 

analysis if streamflows, normalized for drainage area, 

differ between upstream and downstream reaches of 

the river. Although the current sample is too small to 

develop a definitive conclusion, the differences 

between the average of the Wetted-Perimeter and 

R2Cross streamflow requirements for the mainstem 

sites (0.59 ft3/s/mi2) and for the tributary sites 

(0.82 ft3/s/mi2) could indicate that higher streamflows, 

normalized for drainage area, may be needed to 

provide habitat protection in riffles in the headwater 

and tributary portions of the river. 

The degree to which an altered flow regime 

departs from a natural flow regime and the resulting 

change in the structure and composition of a stream's 

aquatic community is poorly understood. More 

information is needed regarding the effects on aquatic 

communities when these streamflow requirements are 

met or not met. To assess the effects of changes in 

streamflow on aquatic communities, studies targeting 

the communities dependent upon flow and the habitats 

likely to be affected by flow changes are needed. In a 

0 10 20 30 40 50 60 70 80 90 100

PERCENT CHANCE DISCHARGE EXCEEDED

100

101

102

103

2

3

4

5

6

7

2

3

4

5

6

7

2

3

4

5

6

7

STREAMFLOW, IN CUBIC FEET PER SECOND

Figure 24. Flow-duration curve for the Usquepaug River near Usquepaug, Rhode Island, gaging station 

(01117420), 1958–2000. 
Summary and Conclusions 53

study of the relation between fish assemblages and 

flow in different stream habitats, Aadland (1993) 

concluded that riffle, raceway, and shallow-pool 

habitats were the most sensitive to flow fluctuations. 

Investigations of streamflow and habitat in the 

Usquepaug–Queen River demonstrated that riffles are 

the first channel type to lose substantial habitat as 

discharge decreases; therefore, assessments of fish and 

macroinvertebrate communities in riffles and nearby 

habitats would serve as a useful indicator of the effects 

of flow alterations on stream health. Application of a 

riffle-based approach for determining streamflow 

requirements in Rhode Island requires more 

information about: (1) the natural seasonal variability 

of hydraulic conditions in riffles, (2) how those 

variations relate to conditions in nearby habitats, and 

(3) how fish and macroinvertebrate assemblages 

use those habitats. Long-term monitoring of fish 

populations in rivers where streamflow requirements 

have been established would improve the 

understanding of the relation between streamflow and 

the reproduction, recruitment, growth, and other 

seasonal life-history needs of stream fish (Tyrus, 1990).

Methods for setting a minimum streamflow for 

habitat protection assume that summer low flow and 

habitat availability are limiting criteria for aquatic life. 

The methods compared in this report do not account for 

other flow-related factors that affect the quality of 

stream habitat such as water quality, temperature, or 

impoundment; nor do the methods directly quantify 

biological trade-offs for different flows or seasons. 

Other methods, such as the Instream Flow Incremental 

Methodology (IFIM) (Bovee and others, 1997), which 

was not used in this study, could be applied to account 

for factors other than flow as a limit on aquatic life, or 

to compare the effects of incremental differences in 

flow created by numerous alternative water uses upon 

specific species or life stages of fish or aquatic 

invertebrates.

SUMMARY AND CONCLUSIONS

Stream habitat, fish communities, and hydrologic 

conditions were investigated in the Usquepaug–Queen 

River Basin in southern Rhode Island. Habitats were 

assessed at 13 sites on the mainstem and tributaries 

from July 1999 to September 2000. Study sites were 

revisited by volunteer teams and by USGS personnel to 

document habitat conditions at different flows. Channel 

types are predominantly low-gradient glides, pools, and 

runs that have a sand and gravel streambed and a forest 

or shrub riparian zone. Fish habitat is provided mostly 

by features along the stream margins such as 

overhanging brush, undercut banks supported by roots, 

and woody debris. These habitat features decrease in 

quality and availability with declining streamflows and 

generally become unavailable once streamflows drop to 

the point at which water recedes from the stream banks. 

In low-gradient reaches, submerged aquatic vegetation 

can provide instream habitat once water recedes from 

the stream banks. The quality of that habitat decreases, 

however, as water depths and velocity decrease with 

declining streamflows. Riffles were identified as 

critical habitat areas because they are among the first to 

exhibit habitat losses during low-flow periods.

Stream-temperature data were collected at eight 

sites during summer 2000 to indicate the suitability of 

those reaches for cold-water fish communities. Stream 

temperatures provide cold-water habitat in the 

Fisherville Brook and Locke Brook tributaries and in 

the mainstem of the Queen River downstream of the 

confluence with Fisherville Brook. Warm stream 

temperatures and impoundments may make marginal 

habitat for cold-water species in the headwaters of the 

Queen River and in the Usquepaug River downstream 

from Glen Rock Reservoir. Consequently, cold-water 

fish communities that may exist in these reaches would 

appear to have little tolerance for additional 

temperature changes that could possibly be created by 

increased water withdrawals. 

Recent fish collections were analyzed to 

determine fish-community composition. Fishcommunity composition was determined for 12 sites 

from tributaries and the Queen River headwaters, 

sampled in 1998, and three sites on the mainstem 

Usquepaug–Queen River sampled in 2000. 

Classification of the fish into habitat-use groups and 

comparison of fish in the mainstem Usquepaug–Queen 

River to target fish communities developed for nearby 

streams in New England indicated that the sampled 

reaches of the mainstem Usquepaug–Queen River 

contained riverine fish species in proportions that are 

near the ranges that could be expected. 

Streamflow data from the gaging station 

Usquepaug River near Usquepaug were used to 

determine streamflow requirements by use of the 

Tennant method and New England Aquatic-Base-Flow 
54 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

method based on the median of monthly mean 

flows for August, and to define a flow regime that 

mimics the river's natural flow regime by use of the 

Range of Variability Approach (RVA). Flows at the 

Usquepaug River gaging station are reduced by 

water withdrawals upstream, and preliminary 

results are presented to indicate lower limits for the 

flow requirements determined by those methods. 

Streamflow requirements for habitat protection for the 

Usquepaug River gaging station were 0.64 ft3/s/mi2

for the Tennant method based on 30-percent of the 

Mean Annual Flow (QMA), and 0.79 ft3/s/mi2 for 

the New England Aquatic-Base-Flow method based 

on the median of monthly mean flows for August. 

Despite summer water withdrawals, the median of 

monthly mean flows for August at the Usquepaug 

gaging station was higher than that for nine nearby 

gaging stations that have virtually unaltered flow. 

These high base flows indicate that high summer 

streamflow requirements may be needed in the 

Usquepaug–Queen River to maintain summer low 

flows within the ranges of naturally occurring low 

flows.

Streamflow requirements for habitat 

protection were determined at seven riffle sites, two 

on the mainstem Usquepaug River, one on the 

mainstem Queen River, and four on tributaries and 

the Queen River headwaters. The median streamflow 

requirements for habitat protection for the mainstem 

and tributary sites, were 0.41 ft3/s/mi2 determined 

by the Wetted-Perimeter method, and 0.72 ft3/s/mi2 

determined by the R2Cross method. R2Cross 

streamflow requirements were higher than WettedPerimeter streamflow requirements for most sites. 

Comparison of median streamflow requirements 

determined by the Wetted-Perimeter and R2Cross 

methods to those determined by the Tennant method 

indicate that R2Cross streamflow requirements would 

provide habitat conditions that were fair to good 

and Wetted-Perimeter streamflow requirements would 

provide habitat conditions that were poor to fair when 

definitions for habitat quality identified by Tennant 

are used. 

The R2Cross and Wetted-Perimeter streamflow 

requirements bracket the lower quartiles of monthly 

mean streamflow for July and August at the Usquepaug 

gage, and include much of the interquartile range of 

flows for September. Streamflows recommended by 

these methods, therefore, fall within the range of flows 

recommended by the RVA for the months of July, 

August, and September, and are below the RVA 

recommended monthly flows for portions of June and 

October.

The streamflow requirement for habitat 

protection, determined from results of the median 

Wetted-Perimeter and R2Cross analyses for unaltered 

sites, were 0.41 and 0.58 ft3/s/mi2, respectively. The 

summer streamflow requirements for the Usquepaug–

Queen River determined by applying the 30-percent 

QMA Tennant method and the ABF method based 

on the median of monthly mean flows for August 

to the Usquepaug River gaging station records 

were 0.64 ft3/s/mi2 and 0.79 ft3/s/mi2, respectively. 

Averaging the results of these four methods results 

in a summer streamflow requirement for habitat 

protection for the Usquepaug–Queen River, to one 

significant figure, of about 0.6 ft3/s/mi2. A streamflow 

requirement of about 0.6 ft3/s/mi2 is within the range of 

the RVA flow-management targets for the months 

of July, August, and September, as determined from 

nearby gaging stations with mostly unaltered 

flow. A flow-duration curve for the Usquepaug gage 

(01117420) shows that under current conditions, 

streamflows would be below this flow for 15 percent 

of the time in an average year. A streamflow of 

0.6 ft3/s/mi2 will prevent the Usquepaug–Queen River 

from becoming segmented, and will provide habitat not 

only in the seven study riffles, but also throughout the 

basin. A summer streamflow requirement recalculated 

on the basis of natural flows simulated by the USGS 

using an HSPF model, in combination with a varied 

flow regime identified by the RVA for the remainder of 

the year, will provide habitat to sustain fluvial fish 

communities and protect the stream integrity and 

natural ecosystem functions of unimpounded reaches 

of the Usquepaug–Queen River.
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APPENDIX 1

Study-Site Descriptions and Documentation of Input and 

Calibration Data for HEC-RAS and WinXSPro Models

Appendix 61

APPENDIX 1

STUDY-SITE DESCRIPTIONS AND 

DOCUMENTATION OF INPUT AND 

CALIBRATION DATA FOR HEC-RAS AND 

WINXSPRO MODELS

The Appendix includes study-site descriptions 

and documentation for WINXSPro and HEC-RAS 

models used to simulate hydraulic parameters for 

determination of Wetted-Perimeter and R2Cross 

streamflow requirements for:

1. Site U2, Usquepaug River near Laurel Lane 

2. Site U1, Usquepaug River at Route 138 

3. Site Q5, Queen River near Dawley Road

4. Site Q3, Queen River near William Reynolds Road

5. Site L1, Locke Brook at Mail Road 

6. Site F2, Fisherville Brook at Liberty Church Road

7. Site F1, Fisherville Brook near Pardon Joslin Road

The values in the appendix tables are the output 

data from the models. For some instances, there may be 

small differences between the values in these tables and 

those appearing in the text. For example, the slopes 

reported in the text are the values input into the model. 

These values may differ slightly from the slopes in the 

appendix tables because HEC-RAS adjusts the slope at 

higher discharges. Values reported in the appendix for 

the hydraulic parameters used to determine R2Cross 

streamflow requirements (wetted perimeter, mean 

depth, mean velocity) are from the staging tables 

output by the models. The staging tables were created 

for small incremental differences in discharge. For 

some cases, the hydraulic parameters that met the 

R2Cross criteria fell between successive discharges in 

the staging tables. For these cases, the discharge 

meeting the criteria and reported in the text was 

extrapolated between successive values in the staging 

table. Values in the appendix tables, however, are those 

for the discharge in the staging table where the criteria 

are first met. In all cases differences are very minor. 

1. Site U2, Usquepaug River near Laurel Lane, 

Richmond/South Kingstown, Rhode Island

One cross section was surveyed in this reach. 

The cross section was located at the upstream end of 

the riffle. This section is a hydraulic control and creates 

a glide habitat that extends upstream for a considerable 

distance. The riffle cross section is predominantly 

trapezoidal in shape, with a low bank and flood plain 

on the left side of the channel. The flood plain on the 

right bank is absent, because the river at that location is 

adjacent to a steep bank along the right side of the 

stream valley. 

The stream slope in the riffle was surveyed to 

be 0.004 ft/ft, at a low-flow discharge of 25.8 ft3/s. 

Manning’s equation was used to calculate a roughness 

at this discharge of 0.040. Bankfull elevations were 

determined in the field during surveying and the 

channel roughness at bankfull flow was estimated by 

means of Barnes (1967) and Hicks and Mason (1991) 

to be 0.025. Manning’s equation was applied with 

WinXSPro version 2.0 software (U.S. Department of 

Agriculture, 1998) and calibrated to the measured 

conditions, to develop stage-discharge relations at the 

sites. A bankfull flow of 122 ft3/s was estimated by 

determining the discharge corresponding to a bankfull 

stage identified in the field. Bankfull channel width and 

bankful wetted perimeter at the cross section were 

determined to be 28.28 and 28.98 ft, respectively. 

Hydraulic parameters simulated by WinXSPRO and 

used to determine R2Cross and Wetted Perimeter 

streamflow requirements are shown in table 1.1. 

The R2Cross criteria for determining streamflow 

requirements were an average depth of 0.28 ft, a wetted 

perimeter of 14.49 ft, and an average velocity of 

1.0 ft/s. These criteria were determined from the 

model to be met at a discharge of 9.4 ft3/s, or about 

0.28 ft3/s/mi2. At this discharge the water depth in the 

deepest portion of the cross section was about 0.82, 

and the average depth in the section was 0.43 ft. The 

wetted perimeter was 22 ft, or about 76 percent of 

bankfull wetted perimeter. The R2Cross streamflow 

requirement was determined from the discharge 

corresponding to the mean-velocity criterion of 1.0 ft/s, 

the most limiting R2Cross criterion.

A wetted perimeter-discharge relation was 

determined for the cross section with WinXSPRO. 

Breaks in the wetted perimeter-discharge relation 

were used to identify a discharge of about 14 ft3/s, or 

0.41 ft3/s/mi2. At this discharge, the water depth in the 

deepest part of the cross section and the average depth 

of the section were simulated to be 0.94 and 0.5 ft, 

respectively. The wetted perimeter was estimated to be 

24.9 ft, or about 86 percent of bankfull wetted 

perimeter. The mean velocity for the section was 

estimated to be 1.2 ft/s.
62 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

2. Site U1, Usquepaug River at Route 138, 

Richmond/South Kingstown, Rhode Island

Two cross sections were surveyed in this reach. 

Both cross sections are located within a riffle with 

moderate slope and do not serve as isolated hydraulic 

controls. The channel cross sections are roughly 

trapezoidal in shape, with a low flood plain on the left 

side and riprap on the right bank. Alterations to channel 

geometry, hardening of the streambed, riprap along the 

right bank, and an upstream dam could affect the 

streamflow requirements determined by the R2Cross 

and Wetted-Perimeter methods at this site. 

At the upstream section, the water-surface slope 

was surveyed to be 0.006 ft/ft in the area of the riffle 

and 0.005 ft/ft for the reach. Manning’s equation was 

used to calculate a roughness of about 0.075 for 

discharges between 20 and 30 ft3/s. Bankfull elevations 

were determined in the field during surveying, and the 

roughness at bankfull flow was estimated by means of 

Barnes (1967) and Hicks and Mason (1991) to be 0.05. 

Manning’s equation was applied using WinXSPro 

version 2.0 software (U.S. Department of Agriculture, 

1998) and calibrated to the measured conditions to 

develop stage-discharge relations at the site. Bankfull 

flow at the site was estimated to be 116 ft3/s. Bankfull 

channel width and bankfull wetted perimeter at the 

cross section were determined to be 32.98 and 34.52 ft, 

respectively. Hydraulic parameters simulated by 

WinXSPRO and used to determine R2Cross and 

Wetted-Perimeter streamflow requirements are shown 

in table 1.2. 

The three R2Cross criteria for determining 

streamflow requirements were an average depth of 

0.33 ft, a wetted perimeter of 17.26 ft, and an average 

velocity of 1.0 ft/s. These criteria were determined 

from the model to be met at a discharge of about 

17.0 ft3/s, or about 0.52 ft3/s/mi2. At this discharge, the 

water depth in the deepest portion of the cross section 

was about 0.88, and the average depth in the section 

was 0.59 ft. The wetted perimeter was 30.0 ft, or about 

87 percent of bankfull wetted perimeter. The limiting 

R2Cross criterion was the discharge having a mean 

velocity of 1.0 ft/s. 

A wetted perimeter-discharge relation was 

determined for the cross section with WinXSPRO. 

Because of the section’s flat streambed, possibly 

created by channel alterations, low discharges of about 

0.7 ft3/s will wet the channel to the bottom of the bank 

identified in the field. Depths are extremely shallow at 

this low discharge value, however, and water levels 

are below the top of the cobbles and boulders in the 

streambed. Breaks in the wetted perimeter-discharge 

relation occur at a discharge of about 4.8 ft3/s, or 

0.15 ft3/s/mi2. At this discharge, the depth in the 

deepest part of the cross section and the average depth 

of the section were estimated to be 0.58 and 0.29 ft, 

respectively. The wetted perimeter was estimated to be 

29.34 ft, or about 85 percent of bankfull wetted 

perimeter. The mean velocity for the section was 

estimated to be 0.57 ft/s. 

Table 1.1. Hydraulic criteria simulated by WinXSPRO for the Usquepaug River near Laurel Lane, Richmond/South Kingstown, Rhode Island

[Z, stage; A, area; P, wetted perimeter; W, width; R, hydraulic radius; D, average depth; S, slope; n, Manning's n; V, average velocity; Q, discharge; ft, foot; 

ft3/s, cubic feet per second; ft2, square feet] 

Condition

Hydraulic parameters

Z

(ft)

A

(ft2

)

P

(ft)

W

(ft)

R

(ft)

D

(ft)

S

(ft/ft) n V(ft/s)

Q

(ft3/s)

Meets R2Cross wetted-perimeter criterion 0.43 2.12 14.34 14.16 0.15 0.15 0.004 0.059 0.43 0.92

Meets R2Cross average-depth criterion .60 4.94 18.16 17.95 .27 .28 .004 .055 .69 3.39

Field-identified bottom of bank .72 7.26 21.05 20.81 .34 .35 .003 .052 .84 6.08

Meets R2Cross average-velocity criterion .82 9.39 22.08 21.82 .43 .43 .003 .049 1.00 9.39

Wetted-Perimeter streamflow requirement .94 12.22 24.94 24.66 .49 .50 .003 .046 1.15 14.08

Aquatic-Base-Flow 0.5 ft3/s/mi2 default flow .96 12.71 25.12 24.83 .51 .52 .003 .046 1.19 15.09

Stage of calibration discharge (25.8 ft3/s) 1.12 16.78 26.25 25.91 .64 .65 .003 .042 1.49 24.95

Stage of field-identified bankfull discharge 1.80 35.24 28.98 28.28 1.22 1.25 .003 .025 3.46 121.78
Appendix 63

At the downstream section, the water-surface 

slope was surveyed to be 0.007 ft/ft at a discharge of 

20.6 ft3/s, and 0.006 at a discharge of 32.9 ft3/s. 

Manning’s equation was used to calculate a roughness 

of about 0.08 at a discharge of 20.6 ft3/s. Bankfull 

elevations were determined in the field during 

surveying, and the roughness at bankfull flow was 

estimated by means of Barnes (1967) and Hicks and 

Mason (1991) to be 0.05. Manning’s equation was 

applied with WinXSPro version 2.0 software (U.S. 

Department of Agriculture, 1998) and calibrated to the 

measured conditions to develop stage-discharge 

relations at the site. Bankfull discharge at the site was 

estimated to be about 112 ft3/s. Bankfull channel width 

and bankful wetted perimeter at the cross section were 

determined to be 39.14 and 41.49 ft, respectively. 

Hydraulic parameters simulated by WinXSPRO and 

used to determine R2Cross and Wetted-Perimeter 

streamflow requirements are shown in table 1.3. 

The three R2Cross criteria for determining 

streamflow requirements were an average depth of 

0.39 ft, a wetted perimeter of 20.74 ft, and an average 

velocity of 1.0 ft/s. These criteria were determined 

from the model to be met at a discharge of about 

21.4 ft3/s, or about 0.65 ft3/s/mi2. At this discharge the 

depth in the deepest portion of the cross section was 

about 1.14 ft, and the average depth in the section was 

0.56 ft. The wetted perimeter was 39.24 ft, or about 95 

percent of bankfull wetted perimeter. The limiting 

R2Cross criterion was the discharge having a mean 

velocity of 1.0 ft/s. 

A wetted perimeter-discharge relation was 

determined for the cross section with WinXSPRO. 

Because of the flat streambed across the section, 

possibly created by channel alterations, low discharges 

of about 1.3 ft3/s will wet the channel to the bottom of 

the bank identified in the field. Depths are extremely 

shallow at this low discharge value, however, and are 

below the depth of the top of the cobbles and boulders 

in the streambed. Breaks in the wetted perimeterdischarge relation occur at a discharge of about 

11.4 ft3/s, or 0.35 ft3/s/mi2. At this discharge, the depth 

in the deepest part of the cross section and the average 

depth of the section were estimated to be 0.98 

and 0.41 ft, respectively. The wetted perimeter was 

estimated to be 38.7 ft, or about 93 percent of bankfull 

wetted perimeter. The mean velocity for the section 

was estimated to be 0.75 ft/s. For the R2Cross Method, 

the average of the streamflow requirements for the 

two cross sections was 0.59 ft3/s/mi2. For the WettedPerimeter method, the average of the streamflow 

requirements for the two cross sections was 

0.25 ft3/s/mi2. 

Table 1.2. Hydraulic criteria simulated by WinXSPRO for the Usquepaug River at Route 138, upstream section, Richmond/South Kingstown, Rhode Island

[Z, stage; A, area; P, wetted perimeter; W, width; R, hydraulic radius; D, average depth; S, slope; n, Manning's n; V, average velocity; Q, discharge; ft, feet; 

ft3/s, cubic feet per second; ft2, square feet]

Condition

Hydraulic parameters

Z

(ft)

A

(ft2

)

P

(ft)

W

(ft)

R

(ft)

D

(ft)

S

(ft/ft)

n V

(ft/s)

Q

(ft3

/s)

 Field-identified bottom of bank 0.25 2.03 13.05 12.90 0.16 0.16 0.006 0.095 0.35 0.71

 Meets R2Cross wetted-perimeter criterion .38 3.82 17.46 17.18 .22 .22 .006 .091 .46 1.74

 Wetted-Perimeter streamflow requirement .58 8.34 29.34 28.75 .28 .29 .006 .085 .57 4.78

 Meets R2Cross average-depth criterion .62 9.49 29.42 28.79 .32 .33 .006 .084 .63 5.99

 Aquatic-Base-Flow 0.5 ft3/s/mi2 default flow .84 15.85 29.90 28.97 .53 .55 .006 .078 .94 14.92

 Meets R2Cross average-velocity criterion .88 17.01 29.99 29.00 .57 .59 .006 .076 1.00 16.98

 Stage of calibration discharge (20.6 ft3/s) .93 18.47 30.16 29.13 .61 .63 .006 .075 1.07 19.72

 Stage of calibration discharge (32.9 ft3/s) 1.15 24.96 31.02 29.87 .80 .84 .005 .069 1.38 34.56

 Stage of field-identified bankfull discharge 1.80 45.26 34.52 32.98 1.31 1.37 .005 .050 2.55 115.51
64 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

3. Site Q5, Queen River near Dawley 

Road, Exeter, Rhode Island

The study site is the first riffle downstream of 

the Dawley Road Bridge. Two cross sections were 

surveyed in this reach. The upstream section was at the 

head of the riffle, and the downstream section was 

about 64 ft downstream, near the tail of the riffle. The 

streambed is primarily cobbles and small boulders. The 

channel cross sections are roughly trapezoidal in shape. 

The stream banks of the upstream section and the left 

bank of the downstream section are steep or vertical 

with slightly undercut banks. The bank on the right 

side of the downstream section is soft sediment and 

wetland vegetation, possibly related to a recent 

migration of the channel. There is a large amount of 

submerged aquatic vegetation throughout the riffle, 

which could create backwater conditions at low flows 

(at the same discharge, the stream stage would be 

higher with vegetation in the channel than without 

vegetation). This riffle becomes a run at low to 

moderate flows and may be a marginal site for 

application of the R2Cross method. 

For evaluation purposes, flows were modelled by 

use of both WinXSPRO and by the U.S. Army Corps 

of Engineers' River Analysis System (HEC-RAS) 

(Brunner, 2001). Only the HEC-RAS results are 

reported. Results from the WinXSPRO model indicated 

that the water-surface slope at the downstream cross 

section was greater than that at the upstream cross 

section; this result indicated that the downstream cross 

section should be used to determine streamflow 

requirements. At discharges in the range of those 

required for habitat protection, however, HEC-RAS 

output showed the water surface at the downstream 

section to be higher than the streambed at the upstream 

section, and also showed the slope of the energygrade line to be steeper for the upstream cross section 

than for the downstream cross section. This indicates 

that the downstream cross section may be in a 

backwater condition at low discharges, and that the 

upstream section should be used for the R2Cross and 

Wetted-Perimeter analysis. 

A one-dimensional, steady-flow, water-surfaceprofile model, HEC-RAS, was used to simulate the 

water-surface profile at this study site. The shape of the 

channel and valley were nearly uniform in the area 

where cross sections were surveyed. Consequently, the 

downstream cross section was used to make a template 

for two cross sections downstream of the surveyed 

area, and surveyed water levels were used to adjust the 

elevation of the templated cross sections. The upstream 

cross section and surveyed water surfaces were used to 

make a template and adjust the elevations of two 

additional cross sections, one between the surveyed 

cross sections, and one upstream of the surveyed cross 

sections. The model was run as subcritical flow, with a 

downstream water-surface slope of 0.000282 ft/ft as a 

Table 1.3. Hydraulic criteria simulated by WinXSPRO for the Usquepaug River at Route 138, downstream section, Richmond/South Kingstown, Rhode 

Island

[Z, stage; A, area; P, wetted perimeter; W, width; R, hydraulic radius; D, average depth; S, slope; n, Manning's n; V, average velocity; Q, discharge; ft, feet; 

ft3/s, cubic feet per second; ft2, square feet]

Condition

Hydraulic parameters

Z

(ft)

A

(ft2)

P

(ft)

W

(ft)

R

(ft)

D

(ft)

S

(ft/ft)

n V

(ft/s)

Q

(ft3/s)

 Field-identified bottom of bank 0.47 3.07 12.99 12.40 0.24 0.25 0.007 0.108 0.44 1.40

 Meets R2Cross wetted-perimeter criterion .70 6.80 21.36 20.30 .32 .34 .007 .098 .58 3.94

 Meets R2Cross average-depth criterion .93 13.35 35.97 34.45 .37 .39 .007 .088 .71 9.48

 Wetted-Perimeter streamflow requirement .98 15.13 38.73 37.12 .39 .41 .007 .085 .75 11.40

 Aquatic-Base-Flow 0.5 ft3/s/mi2 default flow 1.04 17.37 38.91 37.26 .45 .47 .006 .083 .85 14.73

 Stage of calibration discharge (20.6 ft3/s) 1.11 19.98 39.13 37.42 .51 .53 .006 .800 .96 19.22

 Meets R2Cross average-velocity criterion 1.14 21.11 39.24 37.50 .54 .56 .006 .078 1.01 21.35

 Stage of calibration discharge (32.9 ft3/s) 1.33 28.29 39.93 38.02 .71 .74 .006 .070 1.35 38.29

Stage of field-identified bankfull discharge 1.77 45.29 41.49 39.14 1.09 1.16 .006 .050 2.47 112.07
Appendix 65

boundary condition. Manning’s roughness values at the 

upstream cross section were varied between 0.145 at 

low flows to 0.05 at a bankfull discharge of 44 ft3/s. 

Hydraulic information from the HEC-RAS models was 

used to determine relations between discharge and 

other hydraulic parameters used to determine 

streamflow requirements (table 1.4).

The HEC-RAS model was used to produce a 

staging table of average depth, average velocity, and 

percent bankfull wetted perimeter for a range of 

discharges. The three R2Cross criteria for determining 

streamflow requirements were an average depth of 

0.30 ft, a wetted perimeter of 15.8 ft, and an average 

velocity of 1.0 ft/s. The limiting R2Cross criterion was 

the discharge having a mean velocity of 1.0 ft/s. These 

criteria were determined from the model to be met at a 

discharge of 33.5 ft3/s, or about 1.82 ft3/s/mi2. At this 

discharge the depth in the deepest portion of the cross 

section was about 1.47 ft, and the average depth in the 

section was 1.30 ft. The wetted perimeter was 31.3 ft, 

or about 99 percent of bankfull wetted perimeter. The 

R2Cross streamflow requirement determined by 

HEC-RAS (33.5 ft3/s) is within about 17 percent of the 

R2Cross streamflow requirement determined by use of 

the WinXS Pro models (27.9 ft3/s).

The elevation of the bottom-of-bank differed 

by about 0.62 ft between the left and right sides of 

the channel for the upper cross section. A wetted 

perimeter-discharge relation was determined for the 

upper cross section with HEC-RAS. The wetted 

perimeter-discharge relation has a sharp break in slope 

that corresponds to stream stage rising over the bottom 

of the left bank, and a less sharp break in slope that 

corresponds to stream stage rising over the bottom 

of the right bank. Because the channel is virtually 

rectangular in cross section, a very low discharge of 

about 0.2 ft3/s corresponds to the sharp break in slope 

at the bottom of the left bank. A discharge of 3.8 ft3/s 

or about (0.21 ft3/s/mi2) corresponds to the stage equal 

to the average elevation of the left and right bottom-ofbanks. Depths at this discharge are shallow and are 

about at the top of the cobbles and boulders in the 

streambed. At this discharge, the water depth in the 

deepest part of the cross section and the average depth 

of the section were estimated to be 0.38 and 0.35 ft, 

respectively. The wetted perimeter was estimated to be 

28.14 ft, or about 89 percent of bankfull wetted 

perimeter. The mean velocity for the section was 

estimated to be 0.39 ft/s.

Table 1.4. Hydraulic criteria simulated by HEC-RAS for the Queen River near Dawley Road, Exeter, Rhode Island

 [Z, stage; A, area; P, wetted perimeter; W, width; R, hydraulic radius; D, average depth; S, slope; n, Manning's n; V, average velocity; Q, discharge; ft, feet; 

ft3/s, cubic feet per second; ft2, square feet]

Condition

Hydraulic parameters

Z

(ft)

A

(ft2)

P

(ft)

W

(ft)

R

(ft)

D

(ft)

S

(ft/ft)

n V

(ft/s)

Q

(ft3/s)

 Meets R2Cross wetted-perimeter criterion 0.12 0.74 15.85 15.84 0.05 0.05 0.000924 0.145 0.04 0.03

 Lowest field-identified bottom of bank .18 2.02 25.55 25.53 .08 .08 .001509 .143 .07 .15

 Wetted-Perimeter streamflow requirement .20 2.36 25.63 25.59 .09 .09 .001573 .142 .08 .20

 Meets R2Cross average-depth criterion .41 8.08 27.51 27.32 .29 .30 .004322 .134 .32 2.60

 Average field-identified bottom of banks .48 9.84 28.14 27.90 .35 .35 .004738 .132 .39 3.80

 Aquatic-Base-Flow 0.5 ft3/s/mi2 default flow .69 15.57 29.75 29.35 .54 .54 .005238 .123 .58 9.2

 Stage of calibration discharge (7.21 ft3/s) .73 17.26 30.08 29.64 .57 .58 .005202 .122 .61 10.5

 Stage of calibration discharge (15.9 ft3/s) .90 22.09 30.46 29.78 .73 .74 .004800 .115 .72 15.9

 Meets R2Cross average-velocity criterion 1.28 33.48 31.27 29.95 1.07 1.12 .002432 .077 1.00 33.5

 Stage of field-identified bankfull discharge 1.47 39.11 31.67 29.97 1.24 1.30 .001088 .050 1.13 44.0
66 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

4. Site Q3, Queen River near William 

Reynolds Road, Exeter, Rhode Island

Two cross sections were surveyed in the study 

reach, about 100 ft downstream from William 

Reynolds Road. The upper cross section is at the head 

of the riffle, about 15 ft upstream of the downstream 

cross section. The stream has low undercut banks and a 

wide flood plain. The channel cross sections are 

roughly rectangular in shape, and the streambed is 

primarily gravel and cobble. The upper cross section 

was used for the R2Cross analysis.

For evaluation purposes, streamflow 

requirements for habitat protection were determined by 

use of both WinXSPRO and HEC-RAS models. 

Water-surface elevations simulated by the HEC-RAS 

model indicated that the upstream cross section is in 

backwater from the downstream section for most flows. 

Because too few cross sections were surveyed to 

calibrate the HEC-RAS model for the downstream 

cross section within an acceptable level of confidence, 

few water surfaces were surveyed between cross 

sections, and the channel in this reach was too 

heterogeneous to allow templated cross sections to be 

added between surveyed cross sections, the HEC-RAS 

results were not used to determine streamflow 

requirements at this site, and the WinXSPRO results 

are reported.

At the downstream section, the water-surface 

slope was surveyed to be 0.078 ft/ft in the area of the 

riffle and 0.010 ft/ft for the reach. Manning’s equation 

was used to calculate a roughness of about 0.082 at a 

discharge of 1.76 ft3/s. Bankfull elevations were 

determined in the field during surveying and the 

roughness at bankfull flow was estimated by 

means of Barnes (1967) and Hicks and Mason (1991) 

to be 0.040. Manning’s equation was applied with 

WinXSPro version 2.0 software (U.S. Department of 

Agriculture, 1998) and calibrated to the measured 

conditions, to develop stage-discharge relations at 

the site. The bankfull discharge was estimated to be 

about 68 ft3/s. Bankfull channel width and bankful 

wetted perimeter at the cross section were determined 

to be 17.5 and 19.4 ft, respectively. Hydraulic 

parameters simulated by WinXSPRO and used to 

determine R2Cross and Wetted-Perimeter streamflow 

requirements are shown in table 1.5. 

The three R2Cross criteria for determining 

streamflow requirements were an average depth of 

0.20 ft, a wetted perimeter of 9.68 ft, and an average 

velocity of 1.0 ft/s. These criteria were determined 

from the model to be met at a discharge of 6.96 ft3/s, or 

about 1.86 ft3/s/mi2. At this discharge the depth in the 

deepest portion of the cross section was about 0.74 ft, 

and the average depth in the section was 0.43 ft. The 

wetted perimeter was 17.09 ft, or about 88 percent of 

bankfull wetted perimeter. The limiting R2Cross 

criterion was the discharge having a mean velocity of 

1.0 ft/s. 

A wetted perimeter-discharge relation for the 

cross section was determined with WinXSPRO. Breaks 

in the wetted perimeter-discharge relation correspond 

to a fully wetted channel bed at a discharge of about 

2.38 ft3/s, or 0.63 ft3/s/mi2. At this discharge, the

Table 1.5. Hydraulic criteria simulated by WinXSPRO for the Queen River near William Reynolds Road, Exeter, Rhode Island

[Z, stage; A, area; P, wetted perimeter; W, width; R, hydraulic radius; D, average depth; S, slope; n, Manning's n; V, average velocity; Q, discharge; ft, feet; 

ft3/s, cubic feet per second; ft2, square feet]

Condition

Hydraulic parameters

Z

(ft)

A

(ft2)

P

(ft)

W

(ft)

R

(ft)

D

(ft)

S

(ft/ft)

n V

(ft/s)

Q

(ft3/s)

Meets R2Cross wetted-perimeter criterion 0.37 1.34 9.75 9.61 0.14 0.14 0.008 0.089 0.4 0.53

Field-identified bottom of bank .38 1.44 10.16 10.01 .14 .14 .008 .089 .41 .59

Meets R2Cross average-depth criterion .50 3.06 15.80 15.47 .19 .20 .008 .083 .53 1.63

Stage of calibration discharge (1.76 ft3/s) .51 3.21 15.95 15.60 .20 .21 .008 .083 .55 1.77

Aquatic-Base-Flow 0.5 ft3/s/mi2 default flow .53 3.53 16.48 16.09 .21 .22 .008 .082 .58 2.05

Wetted-Perimeter streamflow requirement .55 3.86 16.70 16.28 .23 .24 .008 .081 .62 2.38

Meets R2Cross average-velocity criterion .74 6.96 17.09 16.36 .41 .43 .008 .073 1.00 6.96

Stage of field-identified bankfull discharge 1.52 19.92 19.36 17.48 1.03 1.14 .008 .040 3.40 67.8
Appendix 67

depth in the deepest part of the cross section and the 

average depth of the section were estimated to be 0.55 

and 0.24 ft, respectively. The wetted perimeter was 

estimated to be 16.7 ft, or about 86 percent of bankfull 

wetted perimeter. The mean velocity for the section 

was estimated to be 0.62 ft/s.

5. Site L1, Locke Brook at 

Mail Road, Exeter, Rhode Island

Two cross sections were surveyed in the study 

reach, about 600 ft downstream from Mail Road. The 

downstream cross section was about 25 ft downstream 

of the upstream cross section. The downstream cross 

section, which has a steeper slope than the upstream 

cross section, was selected for R2Cross analysis. The 

stream has high banks, the channel is incised, and the 

flood plain is narrow or nonexistent. The channel cross 

sections are roughly trapezoidal in shape, and the 

streambed is primarily cobbles, small boulders, and 

coarse sand.

At the downstream section, the water-surface 

slope was surveyed to be 0.014 ft/ft in the area of the 

riffle and 0.009 ft/ft for the reach. Manning’s equation 

was used to calculate a roughness of 0.090 at a 

discharge of 3.08 ft3/s. Bankfull elevations were 

determined in the field during surveying and the 

roughness at bankfull flow was estimated by means of 

Barnes (1967) and Hicks and Mason (1991) to be 

0.040. To develop stage-discharge relations at the site, 

Manning’s equation was applied with WinXSPro 

version 2.0 software (U.S. Department of Agriculture, 

1998). The model was calibrated to a discharge 

measurement of 3.08 ft3/s, to within 0.3 percent error. 

Bankfull flow at the site was estimated to be about 55 

ft3/s. Bankfull channel width and bankful wetted 

perimeter at the cross section were determined to be 

about 19.4 and about 20.2 ft, respectively. Hydraulic 

parameters simulated by WinXSPRO and used to 

determine R2Cross and Wetted-Perimeter streamflow 

requirements are shown in table 1.6. 

The three R2Cross criteria for determining 

streamflow requirements were an average depth of 

0.20 ft, a wetted perimeter of 10.1 ft, and an average 

velocity of 1.0 ft/s. These criteria were determined 

from the model to be met at a discharge of 5.72 ft3/s, or 

about 1.3 ft3/s/mi2. At this discharge the depth in the 

deepest portion of the cross section was about 0.66 ft, 

and the average depth in the section was 0.26 ft. The 

wetted perimeter was 15.8 ft, or about 78 percent of 

bankfull wetted perimeter. The limiting R2Cross 

criterion was the discharge having a mean velocity of 

1.0 ft/s. 

A wetted perimeter-discharge relation was 

determined for the cross section with WinXSPRO. 

Breaks in the wetted perimeter-discharge relation occur 

at a discharge of about 2.9 ft3/s, or 0.66 ft3/s/mi2. At 

this discharge, the depth in the deepest part of the cross 

section and the average depth of the section were 

estimated to be 0.51 and 0.25 ft, respectively. The 

wetted perimeter was estimated to be about 15.5 ft, 

Table 1.6. Hydraulic criteria simulated by WinXSPRO for Locke Brook at Mail Road, Exeter, Rhode Island

[Z, stage; A, area; P, wetted perimeter; W, width; R, hydraulic radius; D, average depth; S, slope; n, Manning's n; V, average velocity; Q, discharge; ft, feet; 

ft3/s, cubic feet per second; ft2, square feet]

Condition

Hydraulic parameters

Z

(ft)

A

(ft2

)

P

(ft)

W

(ft)

R

(ft)

D

(ft)

S

(ft/ft)

n V

(ft/s)

Q

(ft3/s)

Field-identified bottom of bank 0.27 0.83 7.04 6.88 0.12 0.12 0.015 0.109 0.40 0.33

Meets R2Cross wetted-perimeter criterion .31 1.17 10.56 10.34 .11 .11 .015 .106 .39 .46

Meets R2Cross average-depth criterion .43 2.67 14.08 13.71 .19 .20 .014 .097 .60 1.61

Aquatic-Base-Flow 0.5 ft3/s/mi2 default flow .47 3.24 14.85 14.43 .22 .22 .014 .095 .67 2.18

Wetted-Perimeter streamflow requirement .51 3.83 15.53 15.06 .25 .25 .014 .092 .75 2.87

Stage of calibration discharge (3.07 ft3/s) .09 .77 3.07 15.16 .25 .26 .014 .091 .77 3.07

Meets R2Cross average-velocity criterion .63 5.71 16.80 16.23 .34 .35 .013 .083 1.00 5.72

Stage of field-identified bankfull discharge 1.24 16.58 20.18 19.37 .82 .86 .010 .040 3.32 54.98
68 Assessment of Habitat and Streamflow Requirements for Habitat Protection, Usquepaug–Queen River, Rhode Island, 1999–2000

or about 76 percent of bankfull wetted perimeter. 

The mean velocity for the section was estimated to be 

0.73 ft/s. 

6. Site F2, Fisherville Brook at Liberty 

Church Road, Exeter, Rhode Island

Two cross sections were surveyed in this reach. 

Both cross sections were within the riffle; however, a 

steeper slope measured for the downstream section and 

identical elevations for the mean annual high-water line 

of both cross sections indicate that the downstream 

section is the controlling section and would be more 

appropriate for application of R2Cross analysis. The 

stream has high banks, the channel is incised, and the 

flood plain is narrow or nonexistent. The channel cross 

sections are roughly trapezoidal in shape, and the 

streambed is primarily cobbles, small boulders, and 

coarse sand.

At the downstream section, the water-surface 

slope was surveyed to be 0.015 ft/ft in the area of the 

riffle. Manning’s equation was used to calculate a 

roughness of about 0.090 at a measured discharge of 

3.61 ft3/s. Bankfull elevations were determined in the 

field during surveying, and the roughness at bankfull 

flow was estimated by means of Barnes (1967) and 

Hicks and Mason (1991) to be 0.036. Manning’s 

equation was applied with WinXSPro version 2.0 

software (U.S. Department of Agriculture, 1998) and 

calibrated to the measured conditions to develop stagedischarge relations at the site. Bankfull flow at the site 

was estimated to be 72.2 ft3/s. Bankfull channel width 

and bankful wetted perimeter at the cross section were 

determined to be 17.46 and 20.01 ft, respectively. 

Hydraulic parameters simulated by WinXSPRO and 

used to determine R2Cross and Wetted Perimeter 

streamflow requirements are shown in table 1.7. 

The three R2Cross criteria for determining 

streamflow requirements were an average depth of 

0.20 ft, a wetted perimeter of 10.0 ft, and an average 

velocity of 1.0 ft/s. These criteria were determined 

from the model to be met at a discharge of 5.84 ft3/s, or 

about 0.73 ft3/s/mi2. At this discharge the depth in the 

deepest portion of the cross section was about 0.66 ft, 

and the average depth in the section was 0.39 ft. The 

wetted perimeter was 16.77 ft, or about 84 percent of 

bankfull wetted perimeter. The limiting R2Cross 

criterion was the discharge having a mean velocity of 

1.0 ft/s. 

A wetted perimeter-discharge relation was 

determined for the cross section with WinXSPRO. 

Breaks in the wetted perimeter-discharge relation 

correspond to discharge of about 4.1 ft3/s, or 

0.5 ft3/s/mi2. At this discharge, the depth in the 

deepest part of the cross section and the average depth 

of the section were estimated to be 0.59 and 0.32 ft, 

respectively. The wetted perimeter was estimated to be

Table 1.7. Hydraulic criteria simulated by WinXSPRO for Fisherville Brook at Liberty Church Road, Exeter, Rhode Island

[Z, stage; A, area; P, wetted perimeter; W, width; R, hydraulic radius; D, average depth; S, slope; n, Manning's n; V, average velocity; Q, discharge; ft, feet; 

ft3/s, cubic feet per second; ft2, square feet]

Condition

Hydraulic parameters

Z

(ft)

A

(ft2)

P

(ft)

W

(ft)

R

(ft)

D

(ft)

S

(ft/ft)

n V

(ft/s)

Q

(ft3/s)

Meets R2Cross wetted-perimeter criterion 0.30 1.03 10.14 9.74 0.10 0.11 0.014 0.106 0.36 0.37

Field-identified bottom of bank .38 1.92 12.76 12.13 .15 .16 .014 .101 .49 .94

Meets R2Cross average-depth criterion .45 2.82 14.43 13.59 .20 .21 .014 .097 .61 1.71

Stage of calibration discharge (3.61 ft3/s) .55 4.26 16.01 14.90 .27 .29 .013 .090 .78 3.33

Aquatic-Base-Flow 0.5 ft3/s/mi2 default flow .59 4.86 16.45 15.24 .30 .32 .013 .088 .86 4.18

Wetted-Perimeter streamflow requirement .59 4.86 16.45 15.24 .30 .32 .013 .088 .86 4.18

Meets R2Cross average-velocity criterion .66 5.93 16.77 15.39 .35 .39 .013 .083 1.01 5.98

Stage of field-identified bankfull discharge 1.42 18.57 20.01 17.46 .93 1.06 .010 .036 3.89 72.22
Appendix 69

16.4 ft, or about 94 percent of bankfull wetted 

perimeter. The mean velocity for the section was 

estimated to be 0.86 ft/s.

7. Site F1, Fisherville Brook near Pardon 

Joslin Road, Exeter, Rhode Island

Two cross sections were surveyed in the study 

reach about 300 ft downstream from a small dam on 

Fisherville Brook. The upper cross section is at the 

head of a riffle, about 20 ft upstream of the downstream 

cross section. The stream in this reach is a series of 

small riffles. The upstream cross section was selected 

for R2Cross analysis because it is a hydraulic control. 

The downstream section, surveyed to calculate slope, 

was determined to be in backwater at low to moderate 

flows; therefore, it was not used in the analysis.

At the upstream section, the water-surface slope 

was surveyed to be 0.011 ft/ft in the area of the riffle. 

Manning’s equation was used to calculate a roughness 

of about 0.055 at a discharge of 1.24 ft3/s. Bankfull 

elevations were determined in the field during 

surveying, and the roughness at bankfull flow was 

estimated by means of Barnes (1967) and Hicks and 

Mason (1991) to be 0.035. Manning’s equation was 

applied with WinXSPro version 2.0 software (U.S. 

Department of Agriculture, 1998) and calibrated to the 

measured conditions, to develop stage-discharge 

relations at the site. Bankfull discharge at the site was 

estimated to be about 20.7 ft3/s. Bankfull channel 

width and bankful wetted perimeter at the cross section 

were determined to be about 15.3 and 15.8 ft, 

respectively. Hydraulic parameters simulated by 

WinXSPRO and used to determine R2Cross and 

Wetted-Perimeter streamflow requirements are shown 

in table 1.8. 

The three R2Cross criteria for determining 

streamflow requirements were an average depth of 

0.20 ft, a wetted perimeter of 7.90 ft, and an average 

velocity of 1.0 ft/s. These criteria were determined 

from the model to be met at a discharge of 2.46 ft3/s, or 

about 0.58 ft3/s/mi2. At this discharge, the depth in the 

deepest portion of the cross section was about 0.35 ft, 

and the average depth in the section was 0.22 ft. The 

wetted perimeter was 11.7 ft, or about 74 percent of 

bankfull wetted perimeter. The limiting R2Cross 

criterion was the discharge having a mean velocity of 

1.0 ft/s. 

A wetted perimeter-discharge relation was 

determined for the cross section with WinXSPRO. 

Breaks in the wetted perimeter-discharge relation occur 

at a discharge of about 1.38 ft3/s, or 0.33 ft3/s/mi2. At 

this discharge, the depth in the deepest part of the cross 

section and the average depth of the section were 

estimated to be 0.28 and 0.15 ft, respectively. The 

wetted perimeter was estimated to be about 11.1 ft, or 

about 70 percent of bankfull wetted perimeter. The 

mean velocity at the wetted-perimeter flow 

requirement was estimated to be 0.81 ft/s.

Table 1.8. Hydraulic criteria simulated by WinXSPRO for Fisherville Brook near Pardon Joslin Road, Exeter, Rhode Island

[Z, stage; A, area; P, wetted perimeter; W, width; R, hydraulic radius; D, average depth; S, slope; n, Manning's n; V, average velocity; Q, discharge; ft, feet; ft2, 

square feet; ft3/s, cubic feet per second]

Condition

Hydraulic parameters

Z

(ft)

A

(ft2)

P

(ft)

W

(ft)

R

(ft)

D

(ft)

S

(ft/ft)

n V

(ft/s)

Q

(ft3/s)

Meets R2Cross wetted-perimeter criterion 0.16 0.57 7.90 7.89 0.07 0.07 0.012 0.058 0.48 0.28

Stage of calibration discharge (1.24 ft3/s) .27 1.60 10.98 10.95 .15 .15 .011 .055 .78 1.24

Field-identified bottom of bank .27 1.60 10.98 10.95 .15 .15 .011 .055 .78 1.24

Wetted-Perimeter streamflow requirement .28 1.71 11.09 11.06 .15 .15 .011 .055 .81 1.38

Aquatic-Base-Flow 0.5 ft3/s/mi2 default flow .32 2.16 11.44 11.38 .19 .19 .100 .540 .92 1.99

Meets R2Cross average-depth criterion .33 2.27 11.53 11.46 .20 .20 .010 .053 .95 2.16

Meets R2Cross average-velocity criterion .35 2.50 11.70 11.62 .21 .22 .010 .053 1.01 2.52

Stage of field-identified bankfull discharge .94 10.55 15.81 15.31 .67 .69 .004 .035 1.96 20.66