Estimated Water Use and Availability in the 

East Narragansett Bay Study Area, 

Rhode Island, 1995–99

By Emily C. Wild

Prepared in cooperation with the Rhode Island Water Resources Board

Scientific Investigations Report 2007–5168

U.S. Department of the Interior

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

DIRK KEMPTHORNE, Secretary

U.S. Geological Survey

Mark D. Myers, Director

U.S. Geological Survey, Reston, Virginia: 2007

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Suggested citation:

Wild, E.C., 2007, Estimated water use and availability in the East Narragansett Bay study area: U.S. Geological Survey 

Scientific Investigations Report 2007–5168, 51 p.
iii

Contents

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

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

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

Previous Investigations........................................................................................................................2

The East Narragansett Bay Study Area ............................................................................................6

Climate ....................................................................................................................................................7

Land Use ................................................................................................................................................7

Study-Area Regions and Minor Civil Divisions ..............................................................................10

Northeastern Narragansett Region ........................................................................................13

Southeastern Narragansett Region ........................................................................................15

East Narragansett Islands Region ..........................................................................................15

Water Use .....................................................................................................................................................16

New England Water-Use Data System ...........................................................................................18

Public Water Supply and Potable-Water Interbasin Transfers ...................................................18

Domestic Water Use ..........................................................................................................................29

Public-Supply Use .....................................................................................................................29

Self-Supply Use ..........................................................................................................................29

Commercial and Industrial Water Use ............................................................................................29

Public-Supply Use .....................................................................................................................29

Self-Supply Use ..........................................................................................................................31

Agricultural Water Use ......................................................................................................................31

Return Flow and Wastewater Interbasin Transfers ......................................................................33

Site-Specific Return Flow .........................................................................................................33

Return Flow from Wastewater-Treatment Facilities ...........................................................34

Septic-System Return Flow ......................................................................................................35

Interbasin Transfers of Wastewater .......................................................................................35

Water-Use Summary ..........................................................................................................................36

Water Availability .........................................................................................................................................37

Summer Ground-Water Availability at Selected Index Stations .................................................37

Summer Water Availability in the Regions .....................................................................................39

Water Budget ......................................................................................................................................42

Summary........................................................................................................................................................45

Acknowledgments .......................................................................................................................................46

Selected References ...................................................................................................................................46

Glossary .........................................................................................................................................................50
iv

Figures

1. Map showing the East Narragansett Bay study area and regions, eastern Rhode 

Island, and the contiguous basins in Massachusetts ............................................................3

2–3. Diagrams showing—

2. The modified hydrologic cycle...........................................................................................4

3. The components of water use ...........................................................................................5

4–5. Maps showing—

4. Surface-water reservoirs, stream-gaging stations, and wastewater-treatmentplants associated with the East Narragansett Bay study area, eastern Rhode 

Island and southeastern Massachusetts, 1995–99 ......................................................12

5. Surficial geology and selected withdrawal wells for the regions in the East

Narragansett Bay study area, eastern Rhode Island, 1995–99 ..................................14

6–8. Graphs showing—

6. Public-supply withdrawals, and self-supply domestic, commercial, industrial, 

and agricultural withdrawals for the regions in the East Narragansett Bay study 

area, eastern Rhode Island, 1995–99 ..............................................................................16

7. Public-supply and self-supply domestic, commercial, industrial, and agriculturalwater use for the regions in the East Narragansett Bay study area, eastern 

Rhode Island, 1995–99 .......................................................................................................17

8. Wastewater-treatment facilities, Rhode Island Pollutant Discharge Elimination

System, and self-disposed domestic, commercial, and industrial water return 

flow for the regions in the East Narragansett Bay study area, eastern Rhode 

Island, 1995–99....................................................................................................................17

9. Map showing Rhode Island water-supply districts in the East Narragansett Bay 

study area, 1995–99 ....................................................................................................................19

10–14. Diagrams showing—

10. Bristol County Water Authority withdrawals, imports, treatment, distributions, and 

estimated water uses in the East Narragansett Bay study area, eastern Rhode 

Island, 1995–99....................................................................................................................23

11. East Providence Water District imports, wholesale purchases, distributions, and

estimated water uses in the East Narragansett Bay study area, eastern Rhode

Island, 1995–99....................................................................................................................25

12. North Tiverton Fire District imports, wholesale purchases, distributions, and

estimated water uses in the East Narragansett Bay study area, eastern Rhode

Island, 1995–99....................................................................................................................26

13. Stone Bridge Fire District withdrawals, distributions, and estimated water uses 

in the East Narragansett Bay study area, 1995–99.......................................................27

14. Newport Water Works withdrawals, distributions, and estimated water uses

in the East Narragansett Bay study area and basin exports, 1995–99......................28

15–17. Graphs showing—

15. Water-level altitudes for Little Compton well 142, 1992–2004.....................................39

16. Water-level altitudes for Portsmouth well 551, 1992–2004..........................................40

17. Water-level altitudes for Tiverton well 274, 1992–2004 ................................................40

18. Maps showing the water withdrawal-to-water-availability ratio for (A ) July, (B ) 

August, and (C ) September for the regions in the East Narragansett Bay study area at 

the 50th percentile for the 7-day, 10-year low-flow scenario .............................................42
v

Tables

1. Total town populations by region for 1990, estimated populations for 1995–99, and

estimated public- and self-supply and public- and self-disposal populations in the

East Narragansett Bay study area, eastern Rhode Island, 1995–99 ....................................6

2. Summary of climatological data pertinent to the East Narragansett Bay study area,

eastern Rhode Island ...................................................................................................................7

3. Town land area and land-use area by category in the regions of the East

Narragansett Bay study area, eastern Rhode Island, 1995–99.............................................8

4. Land-use areas by category for towns and public water suppliers in the regions of

the East Narragansett Bay study area, eastern Rhode Island, 1995–99 .............................9

5. Land-use areas by category for the public water suppliers in the East Narragansett

Bay study area, eastern Rhode Island, 1995–99....................................................................10

6. Defined 10-digit and 12-digit cataloging units in the Watershed Boundary Dataset

and in the East Narragansett Bay study area in Rhode Island...........................................11

7. Public-supply withdrawals in the East Narragansett Bay study area, eastern 

Rhode Island, 1995–99................................................................................................................20

8. Public water-supply imports and wholesale purchases to the East Narragansett

Bay study area, eastern Rhode Island, 1995–99....................................................................21

9. Minor public suppliers by region in the East Narragansett Bay study area, eastern

Rhode Island, 1995–99................................................................................................................21

10. Ground-water and surface-water withdrawals by town and region in the East

Narragansett Bay study area, eastern Rhode Island, 1995–99...........................................22

11. Estimated water use by town and region in the East Narragansett Bay study area,

eastern Rhode Island, 1995–99.................................................................................................30

12. Consumptive water use by town and region in the East Narragansett Bay study area, 

eastern Rhode Island, 1995–99.................................................................................................30

13. Estimated water use per 2-digit Standard Industrial Classification code by town in

the East Narragansett Bay study area, eastern Rhode Island, 1995–99 ...........................32

14. Estimated public- and self-disposed domestic, commercial, and industrial, and total

self-disposed wastewater by region in the East Narragansett Bay study area, eastern 

Rhode Island, 1995–99................................................................................................................33

15. Return flows by region for the Rhode Island Pollutant Discharge Elimination System

sites in the East Narragansett Bay study area, eastern Rhode Island, 1995–99..............34

16. Return flows to Narragansett Bay from wastewater-treatment facilities that are in

the study area and serve towns in and outside of the East Narragansett Bay study

area, eastern Rhode Island, 1995–99.......................................................................................35

17. Summary of estimated water withdrawals, imports, exports, use, nonaccount

water use, consumptive use, and return flow in the East Narragansett Bay study

area, eastern Rhode Island, 1995–99.......................................................................................36

18. U.S. Geological Survey stream-gaging stations and minimum streamflows used in

the analysis of water availability in the East Narragansett Bay study area, eastern

Rhode Island................................................................................................................................38

19. Summer water availability from base flows for the selected index stream-gaging

stations used in the water-availability analysis for the East Narragansett Bay study

area, Rhode Island......................................................................................................................38

20. Estimated gross yield, gross yield for the 7-day, 10-year low flow, and gross yield for 

the Aquatic Base Flow from ground water and surface-water reservoirs in June, July, 

August, and September in the East Narragansett Bay study area, Rhode Island...........41
vi

Conversion Factors, Datums, and Abbreviations

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

square foot (ft2) 0.09290 square meter (m2)

square inch (in2) 6.452 square centimeter (cm2

)

square mile (mi2) 2.590 square kilometer (km2) 

Volume

million gallons (Mgal) 3,785 cubic meter (m3)

Flow rate

gallon per day (gal/d) 0.003785 cubic meter per day (m3/d)

million gallons per day (Mgal/d) 0.04381 cubic meters per second (m3/s)

million gallons per day per square

mile [(Mgal/d)/mi2]

1,461 cubic meter per day per square

kilometer [(m3/d)/km2]

inch per hour (in/h) 0.0254 meter per hour (m/h)

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

°C=(°F-32)/1.8

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 

1929 (NGVD 29).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

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

To convert water-use data to cubic feet per second, multiply million gallons per day by 1.5466.

21. Average public- and self-supply withdrawals in June, July, August, and September

in the regions of the East Narragansett Bay study area, eastern Rhode Island,

1995–99 .........................................................................................................................................43

22. Estimated withdrawal-to-availability ratios for June, July, August, and September in 

the East Narragansett Bay study area, eastern Rhode Island............................................43

23. Average long-term water budget by region for the East Narragansett Bay study area, 

eastern Rhode Island .................................................................................................................44
vii

ABBREVIATIONS and ACRONYMS

7Q10 7-day, 10-year low flow

ABF Aquatic Base Flow

CFR Code of Federal Regulations

CSO Combined sewer overflow

FGDC Federal Geographic Data Committee

HUC hydrologic unit code

IWR-MAIN Institute of Water Resources, Municipal and Industrial Needs System

MCD minor civil division

NCDC National Climatic Data Center

NEWUDS New England Water-Use Data System

NRCS Natural Resources Conservation Service

RIDEM Rhode Island Department of Environmental Management

RIEDC Rhode Island Economic Development Corporation

RIGIS Rhode Island Geographic Information System

RIPDES Rhode Island Pollutant Discharge Elimination System

RIWRB Rhode Island Water Resources Board

SCS Soil Conservation Service

SIC Standard Industrial Classification

TIGER Topologically Integrated Geographic Coding and Referencing

USDA U. S. Department of Agriculture

USEPA U. S. Environmental Protection Administration

USGS U. S. Geological Survey

WBD Watershed Boundary Dataset

WSO weather-station observatory

WWTF wastewater-treatment facility

Abstract

Water availability became a concern in Rhode Island 

during a drought in 1999, and further investigation was needed 

to assess the current demands on the hydrologic system from 

withdrawals during periods of little to no precipitation. The 

low ground-water levels and streamflows measured in Rhode 

Island prompted initiation of a series of studies on water 

use and availability in each major drainage area in Rhode 

Island for the period 1995–99. The investigation of the East 

Narragansett Bay area is the last of these studies. The East 

Narragansett Bay study area (130.9 square miles) includes 

small sections of the Ten Mile and Westport River Basins in 

Rhode Island. The area was divided into three regions (islands 

and contiguous land areas separated by the bay) within each of 

which the freshwater water use and availability were assessed.

During the study period from 1995 through 1999, three 

major public water suppliers in the study area withdrew 

7.601 million gallons per day (Mgal/d) from ground-water 

and surface-water reservoirs. The estimated water withdrawals 

by minor public water suppliers during the study period 

were 0.063 Mgal/d. Total self-supply domestic, industrial, 

commercial, and agricultural withdrawals from the study 

area averaged 1.891 Mgal/d. Total water use in the study 

area averaged 16.48 Mgal/d, of which about 8.750 Mgal/d 

was imported from other basins. The average return flow to 

freshwater within the basin was 2.591 Mgal/d, which included 

effluent from permitted facilities and septic systems. The 

average return flow to saltwater (Narragansett Bay) outside of 

the basin was about 45.21 Mgal/d and included discharges by 

permitted facilities (wastewater-treatment plants and Rhode 

Island Pollutant Discharge Elimination Systems). 

The PART program, a computerized hydrographseparation application, was used for the data collected at two 

selected index stream-gaging stations in the East Narragansett 

Bay study area to determine water availability on the basis of 

the 75th, 50th, and 25th percentiles of the total base flow; the 

base flow for the 7-day, 10-year low-flow scenario; and the 

base flow for the Aquatic Base Flow scenario for both stations. 

Base flows in the study area were lowest in September for the 

75th, 50th, and 25th percentiles. The safe yields determined 

for the surface-water reservoirs (14.10 Mgal/d) were added 

to the estimated available ground water (gross yield) in the 

Southeastern Narragansett and East Narragansett Islands 

regions to give the total available water. 

The water availability in the study area at the 50th 

percentile ranged from 33.18 Mgal/d in September to 

94.62 Mgal/d in June, water availability for the 7-day, 

10-year low-flow scenario at the 50th percentile ranged 

from 21.87 Mgal/d in September to 83.03 Mgal/d in 

June, and water availability for the Aquatic Base Flow 

scenario at the 50th percentile ranged from 14.10 Mgal/d 

in August and September to 65.48 Mgal/d in June. 

Because water withdrawals and use are greater during 

the summer than at other times of the year, water availability 

in June, July, August, and September was compared to water 

withdrawals in the three regions. For the study period, the 

withdrawals in July were higher than in the other summer 

months. For the 50th percentile, the ratios of water withdrawn 

to water available were close to one in August for the 

estimated basic and Aquatic Base Flow scenarios and in 

September for the estimated 7-day, 10-year low-flow scenario. 

For the 25th percentile, the ratios were close to one in August 

for the estimated basic and for the 7-day, 10-year low-flow 

scenario, and were close to one in July for the estimated 

Aquatic Base Flow scenario. 

A long-term water budget was calculated for the East 

Narragansett Bay study area to identify and assess inflows and 

outflows by region. The water withdrawals and return flows 

used in the budget were from 1995 through 1999. Total inflow 

and outflow were calculated separately for each region. Inflow 

was assumed to equal outflow; the total water budget was 

292.1 Mgal/d for the study area. Precipitation and return flow 

were 99 and less than 1 percent of the total estimated inflow 

to the study area, respectively. Evapotranspiration, streamflow, 

and water withdrawals were 47, 49, and 3 percent of the total 

outflow from the study area, respectively. 

Estimated Water Use and Availability in the East 

Narragansett Bay Study Area, Rhode Island, 1995–99

By Emily C. Wild
2 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Introduction

Water availability became a concern to the State of 

Rhode Island during a drought in 1999, and an investigation 

was needed to assess water use and availability in the state, 

including the East Narragansett Bay area (fig. 1). The area, 

which consists of islands and parts of major areas separated 

by the bay, was divided into three regions within each of 

which freshwater water use and availability were assessed. 

The Northeastern Narragansett region consists of the towns 

Barrington, Bristol, East Providence, and Warren; the 

Southeastern Narragansett region consists of the towns Little 

Compton and Tiverton; and the East Narragansett Islands 

region consists of the towns Middletown, Newport, and 

Portsmouth. The entire area of each town is included in the 

study area. 

During the summer of 1999, the average precipitation for 

the Kingston, Rhode Island, climatological station for June 

was only about 0.05 in., compared to the 30-year (1971–2000) 

long-term average precipitation of 3.936 in. for June. Because 

precipitation is a key component of surface-water runoff and 

ground-water infiltration (fig. 2), the rain deficiency caused a 

period of little to no recharge. As a result, ground-water levels 

and streamflows dropped below their long-term averages 

throughout Rhode Island.

To address water-use and availability concerns in 

Rhode Island, the U.S. Geological Survey (USGS), in 

cooperation with the Rhode Island Water Resources Board 

(RIWRB), began a series of nine water-use and availability 

investigations in different basins or areas for the calendar 

years 1995–1999. The RIWRB serves as a water-sourcing 

agency to ensure future water availability for residential 

growth and economic development for all Rhode Islanders 

(Rhode Island Water Resources Board, 2003). The purpose 

of the studies was to determine the relations between 

the components of the hydrologic cycle (fig. 2) and the 

water-use components (fig. 3) during periods of little to no 

recharge. The East Narragansett Bay area may present less 

concern than other areas to the State of Rhode Island in the 

assessment of water use and availability, however, because 

surface-water withdrawals and wholesale water purchases 

from outside the study area were the predominant water 

sources for public suppliers during the study period. The 

results of this study and additional studies of other basins in 

or adjacent to Rhode Island will be used to compare water 

demands to water availability for times of little to no recharge, 

particularly during June, July, August, and September. 

Purpose and Scope

This report identifies the water-use components and 

assesses the water use and availability in the three coastal 

areas (regions) of the East Narragansett Bay study area for 

calendar years 1995–1999. To estimate water use, data on 

water withdrawals, use, and discharges were collected for 

the towns in the study area. These data were organized and 

retrieved by using the New England Water-Use Data System 

(NEWUDS). The methods used to estimate the ground-water 

availability for the three regions are described for streamflowrecession periods in the summer. The concept of safe yield, 

defined by the Rhode Island Water Resources Board (2008) 

as “a substantial withdrawal that can be continuously supplied 

from a surface-water-supply source without adverse effects 

throughout a critical dry period with a 1-percent chance of 

occurrence, or one [a dry period] that is equivalent to the 

drought of record, whichever is more severe.” Previously 

determined safe yields were used to determine the surface 

water available from reservoirs, and these values were added 

to the estimated ground water available to determine the 

total water available (or the total gross yield). Finally, the 

report presents a study-area water budget. It summarizes the 

components of the hydrologic cycle for the long-term period 

of record for the index stream-gaging station for each region 

and selected water-use components for the study period. 

Previous Investigations

The USGS has been monitoring ground-water levels 

for about 15 years (as of 2007) in the East Narragansett 

Bay study area in Rhode Island. Historically, there was one 

continuous stream-gaging station in the study area at which 

discharge data were collected from 1940 through 1987. Few 

studies have described the ground-water and surface-water 

resources in the East Narragansett Bay area. The study area 

includes parts of the Bristol, East Providence, Fall River, 

Newport, Providence, Prudence Island, Sakonnet Point, and 

Tiverton USGS quadrangles. The USGS has published these 

quadrangles in detailed thematic maps that describe the 

bedrock geology (Lyons, 1977; Moore, 1975; Pollock, 1964; 

Quinn, 1959; Quinn and Springer, 1954) and surficial geology 

(Smith, 1955, 1956). Several previous ground-water investigations were completed by the USGS in cooperation with 

the RIWRB (Allen and Blackhall, 1950; Allen and Gorman, 

1959; Bierschenk, 1954, 1959; and Schiner, 1964a, 1964b). 
Introduction 3

NORTH

KINGSTOWN

SOUTH

KINGSTOWN EXETER

NARRAGANSETT

NEWPORT

JAMESTOWN

MIDDLETOWN

LITTLE

COMPTON

PORTSMOUTH

PORTSMOUTH

TIVERTON

WESTPORT

DARTMOUTH

BRISTOL

GOSNOLD

NEW

BEDFORD

FAIRHAVEN

ACUSHNET

ROCHESTER

FALL RIVER

FREETOWN

DIGHTON BERKLEY

LAKEVILLE

TAUNTON

RAYNHAM

BRIDGEWATER

MIDDLEBOROUGH

HALIFAX

EASTON EAST

BRIDGEWATER HANSON

FOXBOROUGH

MANSFIELD

ATTLEBOROUGH

NORTH

ATTLEBOROUGH

NORTON

REHOBOTH

PAWTUCKET

CENTRAL FALLS

CUMBERLAND

WOONSOCKETBELLINGHAM BLACKSTONE

FRANKLIN WRENTHAM

PLAINVILLE

NORTH

SMITHFIELD

SMITHFIELD LINCOLN

NORTH

PROVIDENCE

EAST

PROVIDENCE

PROVIDENCE JOHNSTON

SEEKONK

CRANSTON SWANSEA

WARREN

BARRINGTON

SOMERSET WARWICK

WEST 

WARWICK

EAST

GREENWICH

NARRAGANSETT 

BAY BASIN

WESTPORT

 BASIN

TEN MILE

BASIN

NARRAGANSETT 

BAY BASIN

Moshassuck

River

Woonasquatucket River

Blackstone

River

Pawtuxet

River

Hunt

Providence River

River

Pettaquamscutt River

Ten Mile River

Taunton River

Wading River

Threemile River

Taunton River

Assawompset

Pond

Sakonnet River

East Passage

N

A

R

R

A

G

A

N

S

E

T

T

B

A

Y

B U Z Z A R D S B A Y

MOUNT HOPE GREENWICH BAY BAY

RHODE ISLAND SOUND

POINT

JUDITH

AQUIDNECK

ISLAND

CONANICUT

ISLAND

PRUDENCE

ISLAND

PATIENCE

ISLAND HOG

ISLAND

MASSACHUSETTS

RHODE ISLAND

EXPLANATION

Study-area regions

 Northeastern

 Southeastern

 East Narragansett Islands

Basin boundary (10-digit HUC)

Climatological station

 with rain gage 

4

95

138

195

295

Base map from U.S. Geological Survey, 1983, 1:24,000

Polyconic projection, (NAD 83)

5 MILES

5 KILOMETERS

0

0

2.5

71o30' 71o

15' 71o

41o30'

41o

45'

42o

41o45'

71o45' 71o30'

41o30'

42o00'

0 10 Mi

0 10 Km

RHODE ISLAND

SOUND

Rhode STUDY AREA

Island

Figure 1. The East Narragansett Bay study area and regions, eastern Rhode Island, and the contiguous 

basins in Massachusetts.
4 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

GROUND-WATER INFILTRATION

THE MODIFIED HYDROLOGIC CYCLE

SURFACE WATER

RIVERS AND PONDS

GROUND-WATER DISCHARGE

(BASE FLOW)

SUBSURFACE:

GROUND-WATER AQUIFER

(BEDROCK, STRATIFIED 

SAND AND GRAVEL, OR TILL)

DIRECT RUNOFF

ATMOSPHERE

LAND SURFACE

PRECIPITATIONPRECIPITATION

EVAPOTRANSPIRATIONEVAPOTRANSPIRATION

Figure 2. The modified hydrologic cycle.
Introduction 5

Figure 3. The components of water use.

 

(Ground Water

and Surface Water)

Water Withdrawals

Water Purification

Nonaccount 

Water Use

Water Distribution

Inflow and

Infiltration

 Wastewater 

Collection

WastewaterTreatment

Facility

(Ground Water

and Surface Water)

Return Flow

Consumptive 

Use (Domestic, Industrial,

Commercial, and 

Agricultural)

Nonaccount 

Water Use

Water Use
6 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

In addition, information on water use has been 

collected and compiled in methodological and statewide 

studies (Craft and others, 1995; Horn, 2000; Horn and 

Craft, 1991; and Medalie, 1996). The public water suppliers 

are required to submit Water-Supply Management Plans to 

the RIWRB as a part of the state’s Water Supply Systems 

Management Plan program. That information was used in this 

study and in recent publications on water use and availability 

(Barlow, 2003; Wild and Nimiroski, 2004, 2005; and 

Nimiroski and Wild, 2005). 

The East Narragansett Bay Study Area

The East Narragansett Bay study area is in eastern 

Rhode Island (fig. 1). Land area in the study area totals about 

130.9 mi2, of which about 21.29 mi2 is in the Westport River 

drainage area, and 3.668 mi2 of which about is in the Ten 

Mile River drainage area. The study area includes nine Rhode 

Island towns. In 1990, the study-area population was about 

179,800, and the estimated population during the study period 

was about 175,000 (table 1). Withdrawal data from public 

suppliers for Massachusetts municipalities for the years 1995 

and 1998 were not available, and therefore water-use and 

availability assessments for Massachusetts were not included 

in the study. 

Water use and availability were assessed separately for 

the three regions of the East Narragansett Bay (Northeastern 

Narragansett, Southeastern Narragansett, and Eastern 

Narragansett Islands) because the regions in the area of 

the investigation are separated along the bay and coast by 

saltwater (fig. 1). Prudence, Patience, and Hog Islands were 

included in the Eastern Narragansett Islands region. The 

bay and coastal drainage areas are unique because there is 

little relief and there are multiple areas of direct runoff to 

the bay and ocean. Because of these characteristics, there 

is limited surface-water data collection for these areas. The 

USGS, however, has been collecting ground-water levels 

from observation wells in Little Compton and Portsmouth 

since 1992. The water levels for the wells were analyzed 

only to illustrate the fluctuations of the water table during the 

droughts in 1999 and 2002 and were not part of this study. 

Table 1. Total town populations by region for 1990, estimated populations for 1995–99, and estimated public- and self-supply and 

public- and self-disposal populations in the East Narragansett Bay study area, eastern Rhode Island, 1995–99. 

[Total 1990 populations in Rhode Island from Rhode Island Geographic Information System (1991). Estimated 1995–99 population from the Rhode Island 

Economic Development Corporation (2001).]

City/town Population Estimated 1995–99 population

1990 Estimated

1995–99

Supply Disposal

Public Self Public Self

Northeastern Narragansett region

Barrington 15,847 15,728 14,909 819 15,619 109

Bristol 21,600 21,984 18,877 3,107 19,468 2,516

East Providence 50,375 48,173 48,053 120 46,844 1,329

Warren 11,384 11,369 9,845 1,524 10,028 1,341

Region total 99,206 97,254 91,684 5,570 91,959 5,295

Southeastern Narragansett region

Little Compton 3,335 3,343 88 3,255 53 3,290

Tiverton 14,315 14,194 8,501 5,693 877 13,317

Region total 17,650 17,537 8,589 8,948 930 16,607

 East Narragansett Islands region

Middletown 17,751 18,970 15,837 3,133 16,543 2,427

Newport 28,343 24,536 24,528 8 24,073 463

Portsmouth 16,853 16,721 16,114 607 2,729 13,992

Region total 62,947 60,227 56,479 3,748 43,345 16,882

Study-area total 179,803 175,018 156,752 18,266 136,234 38,784
Introduction 7

Climate

Precipitation and temperature data for the climatological 

station at Kingston, Rhode Island on the University of Rhode 

Island campus and the Providence Weather Station Observatory (WSO) climatological station for the airport in Warwick, 

Rhode Island were compiled by using the monthly and annual 

summaries published in the series “Climatological Data New 

England” from the National Climatic Data Center (NCDC) 

of the National Oceanic and Atmospheric Administration 

(NOAA). In addition, the precipitation data for the climatological station at Taunton, Massachusetts were included because 

of the proximity of the station to the study area (table 2). 

Summary precipitation data are presented in order to 

establish the differences in precipitation along the state and 

coastal areas and the differences between the long-term 

precipitation and the precipitation during the study period 

(table 2). During the study period, the average monthly precipitation ranged from 2.728 in. (July) to 4.474 in. (September) 

for the summer months (June-September) at the Kingston climatological station. At the climatological station in Taunton, 

Massachusetts, the average monthly precipitation ranged from 

2.808 in. (August) to 4.010 in. (September) for the summer. 

Precipitation and temperature data for the climatological stations are summarized in table 2. 

Land Use 

Land use was tabulated, by town, from the Rhode 

Island Geographic Information Systems (RIGIS) land-use 

coverages (table 3). For water-supply districts, the municipality land-use area was used to aggregate the water-use 

categories by town and defined regions in the study area 

(table 4). The total commercial, industrial, and agricultural 

land-use areas were 3.493 mi2, 1.827 mi2, and 8.517 mi2, 

respectively, within the East Narragansett Bay study area 

(table 5). The commercial land-use area for the publicsupply districts ranged from 0.083 mi2 to 1.074 mi2 for 

the Stone Bridge Fire District and East Providence Water 

Department service areas in the East Narragansett Bay study 

area, respectively. The industrial land-use area ranged from 

0.049 mi2 for the North Tiverton Fire District to 0.750 mi2

for the East Providence Water Department service areas 

in the East Narragansett Bay study area, and there was no 

industrial land-use area within the Stone Bridge Fire District 

and Tiverton Water District. The agricultural land-use area 

ranged from 0.103 mi2 for the Stone Bridge Fire District 

to 4.033 mi2 for the Portsmouth Water and Fire District 

service areas in the East Narragansett Bay study area. 

Table 2. Summary of climatological data pertinent to the East Narragansett Bay study area, eastern Rhode Island.

[Climatological data from monthly and annual summaries from the National Climate Data Center of the National Oceanic and Atmospheric Administration, 

1971–2000. MA, Massachusetts; RI, Rhode Island; WSO, weather station observatory; °F, degrees Fahrenheit; in., inches] 

Climatological station Period of record

[study period]

June July August September Annual 

Average temperature (°F)

Kingston, RI 1971–2000 65.63 71.06 69.91 62.72 49.94

[1995–99] 66.50 71.88 70.32 63.74 50.91

Providence Airport WSO, 

Warwick, RI

1971–2000 67.65 73.37 71.88 63.99 51.13

[1995–99] 68.20 74.14 72.08 64.74 51.84

Average total monthly precipitation (in.)

Taunton, MA 1971–2000 3.414 3.960 3.967 4.033 48.44

[1995–99] 3.806 3.312 2.808 4.010 48.84

Kingston, RI 1971–2000 3.936 3.308 4.400 4.163 51.79

[1995–99] 4.106 2.728 4.356 4.474 53.11

Providence Airport WSO, 

Warwick, RI

1971–2000 3.382 3.169 3.904 3.704 46.46

[1995–99] 3.414 1.978 3.190 4.014 43.91
8 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Table 3. Town land area and land-use area by category in the regions of the East Narragansett Bay study area, eastern Rhode Island, 

1995–99. 

[Land-use areas were estimated by using the coverage from the Rhode Island Geographic Information System, 1995a. mi2, square miles] 

City/town Land area (mi2) Land-use area by category (mi2

)

Commercial Industrial Agricultural

Northeastern Narragansett region

Barrington 8.519 0.178 0.019 0.491

Bristol 9.502 .272 .209 1.087

East Providence 13.70 1.075 .749 .186

Warren 6.120 .247 .147 1.320

Region total 37.84 1.772 1.124 3.084

Southeastern Narragansett region

Little Compton 22.05 0.094 0.000 5.696

Tiverton 30.00 .486 .049 3.802

Region total 52.05 0.580 0.049 9.498

East Narragansett Islands region

Middletown 12.50 0.695 0.276 3.496

Newport 7.445 .387 .115 .229

Portsmouth 21.10 .316 .318 4.643

Region total 41.05 1.398 0.709 8.368

Study-area total 130.94 3.750 1.882 20.95
Introduction 9

Table 4. Land-use areas by category for towns and public water suppliers in the regions of the East Narragansett Bay study area, 

eastern Rhode Island, 1995–99. 

[Land-use areas for the water suppliers were estimated by using the coverages from the Rhode Island Geographic Information System (1995a,b). mi2, square 

miles; --, not applicable]

City/town Water suppliers

Total land area in 

water-supply district

(mi2)

Land-use area by category in the East Narragansett 

Bay study area

 (mi2)

Commercial Industrial Agricultural

Northeastern Narragansett region

Barrington Bristol County Water Authority1 8.455 0.179 0.019 0.480

Bristol Bristol County Water Authority1 7.807 .272 .209 .701

East Providence East Providence Water Department1 13.65 1.074 .750 .186

Warren Bristol County Water Authority1 3.834 .240 .144 .467

Southeastern Narragansett region

Little Compton -- -- -- -- --

Tiverton North Tiverton Fire District2 2.685 0.191 0.049 0.114

Stone Bridge Fire District2 2.553 .083 .000 .103

Tiverton Fire District2 1.382 .101 .000 .171

Tiverton total 6.620 0.375 0.049 0.388

East Narragansett Islands region

Middletown Newport Water Works 7.916 0.678 0.276 1.682

Portsmouth Water and Fire District .302 .000 .000 .180

Middletown total 8.218 0.678 0.276 1.862

Newport Newport Water Works 6.846 .360 .115 .225

Portsmouth Newport Water Works 1.437 .029 .019 .355

Portsmouth Water and Fire District 13.39 .286 .246 3.853

Portsmouth total 14.83 0.315 0.265 4.208

Study-area total 70.26 3.493 1.827 8.517

1 Wholesale purchase from the Providence Water Supply Board.

2 These districts are in Tiverton, Rhode Island.
10 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Study-Area Regions and Minor Civil Divisions

The East Narragansett Bay study area differs from study 

areas based on river basins within the state because this 

study area incorporates the remaining individual land areas 

next to the bay and in more than one major drainage basin. 

The three regions (Northeastern Narragansett, Southeastern 

Narragansett, and East Narragansett Islands regions) are 

separated from each other by the saltwater body of Narragansett Bay and were individually assessed for freshwater use and 

availability for this study. In addition, the East Narragansett 

Islands region comprises several independent islands that were 

analyzed together for this region analysis. 

The USGS boundaries for this study were based on 

the availability of freshwater, whereas the other boundaries 

defined by the Watershed Boundary Dataset (WBD) from 

the Natural Resources Conservation Service (NRCS) are 

presented for comparison for the state and local agencies that 

are analyzing several aspects of land-use area by watersheds 

(table 6, fig. 4). The differences exist because the NRCS 

defined the land-area boundaries for this study area on the 

basis of surface-water drainage to saltwater, but the purpose 

of this study was to evaluate freshwater. The WBD was 

developed by using the standards for delineation established 

by the Federal Geographic Data Committee (FGDC) in 

2002. The study area is part of the Narragansett Bay USGS 

8-digit Hydrologic Unit Code area (HUC) and the Cape 

Cod USGS 8-digit HUC area, as well as several 10-digit 

(5 subwatersheds) and 12-digit (13 subwatersheds) cataloging 

units defined by the NRCS basin coverage. A specific example 

of the WBD coverages and the study area definitions is evident 

for Aquidneck Island. Aquidneck Island (officially known as 

Rhode Island, according to the USGS maps), was divided into 

five 12-digit WBD cataloging units, the Upper East Passage 

(010900040907), the Lower East Passage (010900040909), 

the Coastal Aquidneck (010900040911), the Sakonnet River 

(010900040910) and the Mt. Hope Bay (010900040905) 

(fig. 4). Because of these differences, the study area was 

grouped differently by the three regions and apportioned by 

towns for the assessment (table 6). 

The 1990 U.S. Census Bureau’s Topologically Integrated 

Geographic Coding and Referencing (TIGER) data, entered 

into RIGIS, was used to estimate total populations of towns or 

cities (called minor civil divisions (MCDs) by the U.S. Census 

Bureau) by adding the census tracts by town. Total region 

populations were calculated by adding town populations by 

region. Total town-population data compiled by the Rhode 

Island Economic Development Corporation (RIEDC) (2001) 

for the study period (1995–99) were averaged to give the total 

average town population and added by region to give total 

average region population.

Public water suppliers are defined by the U.S. 

Environmental Protection Agency (USEPA) as suppliers 

serving more than 25 people or having 15 service connections 

year round (Code of Federal Regulations (CFR), title 40, 

part 141, section 2, 1996). To estimate the 1995–99 town 

populations on public water and self-supplies and public 

wastewater and self-disposal, population ratios were 

calculated on the basis of the data obtained by merging the 

1990 populations on private wells and the 1990 populations 

on public wastewater collection that were available 

through RIGIS (1991) by overlaying town boundaries. 

Table 5. Land-use areas by category for the public water suppliers in the East Narragansett Bay study area, eastern Rhode Island, 

1995–99. 

[Land-use areas for the water suppliers were estimated by using the coverages from the Rhode Island Geographic Information System (1995a,b). mi2, 

square miles]

 Water suppliers

Total land area in water-supply 

district

(mi2)

Land-use area by category in the 

East Narragansett Bay study area

 (mi2)

Commercial Industrial Agricultural

Bristol County Water Authority1 20.10 0.691 0.372 1.648

East Providence Water Department1 13.65 1.074 .750 .186

North Tiverton Fire District2 2.685 .191 .049 .114

Stone Bridge Fire District2 2.553 .083 .000 .103

Tiverton Fire District2 1.382 .101 .000 .171

Newport Water Works 16.20 1.067 .410 2.262

Portsmouth Water and Fire District 13.69 .286 .246 4.033

Water-supplier totals 70.26 3.493 1.827 8.517

1 Wholesale purchases from the Providence Water Supply Board.

2 These districts are in Tiverton, Rhode Island.
Introduction 11

Table 6. Defined 10-digit and 12-digit cataloging units in the Watershed Boundary Dataset and in the East Narragansett Bay study area in Rhode Island.[The total land area for the study area is 130.94 mi2. Differences between the NRCS WBD and previous coverages are the results of delineating the islands and shorelines. HUC, hydrologic unit code; --, not applicable]

Watershed Boundary Dataset for Narragansett Bay in Rhode Island 12-digit cataloging units in the East Narragansett Bay study area

10-digit cataloging units 12-digit cataloging units

Name

Land 

within 

study area 

(mi2)

 Name Number 

Drainage 

area 

(mi2)

 Name Number 

Drainage 

area 

(mi2)

Rhode Island Sound–Gooseberry Neck to Sakonnet Point1 0109000205 21.64 Westport River–Noquochoke Lake to mouth

Rhode Island Sound–Richmond Pond to Sakonnet Point

 010900020502

 010900020503

 6.812

14.82

Westport River–Noquochoke Lake to mouthRhode Island Sound–Richmond Pond to Sakonnet Point

 6.812

14.82

Ten Mile River2 0109000404 6.850 Ten Mile River 010900040401 6.850 Ten Mile River 3.660

Palmer River2 0109000407 12.21 Palmer River 010900040701 2.196 Palmer River 2.196

Barrington and Warren Rivers 010900040702 10.01 Barrington and Warren Rivers 10.01

Lower Taunton River2 0109000408 6.165 Quequechan River 010900040803 6.163 Quequechan River 6.163

Narragansett Bay2 0109000409 196.7 Seekonk and Providence Rivers 010900040901 24.40 Seekonk and Providence Rivers 11.10

Upper Narragansett Bay 010900040902 9.864 Upper Narragansett Bay 2.767

Greenwich Bay 010900040903 21.17 Greenwich Bay --

Hunt River 010900040904 24.48 Hunt River --Mount Hope Bay 010900040905 10.71 Mount Hope Bay 5.851

Upper West Passage 010900040906 8.146 Upper West Passage --Upper East Passage 010900040907 14.58 Upper East Passage 11.53

Lower West Passage 010900040908 27.04 Lower West Passage --

Lower East Passage 010900040909 11.02 Lower East Passage 6.222Sakonnet River 010900040910 35.81 Sakonnet River 35.81

Coastal Aquidneck 010900040911 9.505 Coastal Aquidneck 9.505

Total for the Watershed Boundary Dataset 10-digit cataloging units

 243.6 Total for the Watershed Boundary Dataset 

12-digit cataloging units 

 243.6 Study-area total 126.45

1Cape Cod 8-digit HUC.2Narragansett 8-digit HUC.
12 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

40901

40701

40401

40902

40906

40907

40910

40911

40909

40905

40803

20502

20503

40702

Kickemuit 

Reservoir

Lawton

Valley

Reservoir

Sisson

Pond

Green

End

Pond

Easton

Pond

Anawan

 Reservoir

Shad

Factory

Pond

Swansea

Reservoir

Kickemuit 

Reservoir North

Watuppa 

Pond

Stafford

Pond

St. 

Mary's

Pond

Nonquit

Pond

Harold E.

Watson

Reservoir

Gardiner

Pond

Nelson

Pond

A

B

C

D

E

BERKLEY

DIGHTON

River

Providence River

Sakonnet River

B U Z Z A R D S B A Y

MOUNT 

HOPE

BAY GREENWICH BAY

AQUIDNECK

ISLAND

CONANICUT

ISLAND

PRUDENCE

ISLAND

PATIENCE

ISLAND

HOG

ISLAND

01109403

01106000

1

1

2

3

4

5

6

7

8

9

RHODE ISLAND SOUND

Taunton River

RHODE ISLAND

MASSACHUSETTS

71o15'

41o30'

41o

45'

71o

5 MILES

5 KILOMETERS

0

0

2.5

Base map from U.S. Geological Survey, 1983, 1:24,000

Polyconic projection, (NAD 83)

EXPLANATION

Study-area regions

 Northeastern

 Southeastern

 East Narragansett Islands

Stream-gaging

 station and number

Rhode Island

 pollutant discharge

 elimination system

 site (RIPDES) and

 reference number—

 See table 15

A

01109403

1

Wastewater-treatment 

 plant and reference letter—See table 16

Twelve-digit hydrologic 

 unit code boundary (last five

 digits shown in purple) 0109000 40401

Figure 4. Surface-water reservoirs, stream-gaging stations, and wastewater-treatment plants associated with the 

East Narragansett Bay study area, eastern Rhode Island and southeastern Massachusetts, 1995–99.
Introduction 13

The resultant ratios of the populations of the towns on 

private wells (self-supply) and wastewater collection (public 

disposal) to the total 1990 populations were applied to 

the total 1995–99 populations to determine the 1995–99 

populations on self-supply and 1995–99 populations on 

public disposal (table 1). The 1995–99 populations on public 

supply and self-disposal were determined by subtracting 

the 1995–99 populations on self-supply and 1995–99 

populations on public disposal, respectively, from the total 

1995–99 population of the town (table 1). This calculation 

was based on the assumption that the ratios remained the 

same from 1990 to the period 1995–99. Public suppliers 

were categorized into major public water suppliers that have 

a system of distribution and minor public water suppliers 

that have closed systems. Minor public water suppliers 

withdraw and use the water on a common property that 

serves a specific residential population, for example, nursing 

homes, condominium associations, and mobile home parks.

Northeastern Narragansett Region

The Northeastern Narragansett region (37.84 mi2) is 

in the northeastern section of the East Narragansett Bay in 

Rhode Island along the Massachusetts border. Towns in the 

region include Barrington, Bristol, East Providence, and 

Warren (fig. 1). Land areas and land-use areas by category 

are summarized in table 3. The border with Massachusetts 

is defined by the Ten Mile River and Runnins River in East 

Providence. The region has several saltwater streams and 

ponds that drain into the bay; these streams and ponds include 

the Hundred Acre Cove, Barrington River, Palmer River, 

Warren River, and Kickemuit River. The surficial deposits in 

the region are 63 percent sand and gravel (fig. 5).

The town of Barrington is on the northern part of the Narragansett Bay in eastern Rhode Island (fig. 1). The total land 

area is 8.519 mi2 (table 3), of which about 6 percent is in the 

Palmer River 12-digit WBD cataloging unit, about 40 percent 

is in the Barrington and Warren Rivers 12-digit WBD cataloging unit, about 43 percent is in the Seekonk and Providence 

Rivers 12-digit WBD cataloging unit, and about 11 percent is 

in the Upper Narragansett Bay 12-digit WBD cataloging unit. 

The estimated total town population for the study period was 

15,728 (table 1). Barrington is in the Bristol County Water 

Authority service area (table 4). The town is in the wastewatercollection area for the East Providence Wastewater-Treatment 

Facility that discharges to the bay. 

The town of Bristol is on the northern part of the 

Narragansett Bay in eastern Rhode Island (fig. 1). The total 

land area is 9.502 mi2 (table 3), of which 9 percent is in the 

Barrington and Warren Rivers 12-digit WBD cataloging 

unit, 57 percent is in the Upper Narragansett Bay and Upper 

East Passage 12-digit WBD cataloging units, and 34 percent 

is in the Mount Hope Bay 12-digit WBD cataloging unit. 

The estimated total town population for the study period 

was 21,984 (table 1). Bristol is in the Bristol County Water 

Authority service area (table 4). The town has a wastewatercollection facility that discharges to the bay, the Bristol 

Wastewater-Treatment Facility.

The City of East Providence is on the northern part of 

the Narragansett Bay in eastern Rhode Island (fig. 1). The 

total land area is 13.70 mi2 (table 3), of which about 7 percent 

is in the Ten Mile River 12-digit WBD cataloging unit, 

about 53 percent is in the Seekonk and Providence Rivers 

12-digit WBD cataloging unit, and about 20 percent is in 

the Barrington and Warren Rivers 12-digit WBD cataloging 

unit. The estimated town population for the study period was 

48,173 (table 1). The East Providence Water Department 

supplies water to the residents of the town. Wastewater is 

collected in the town by the East Providence WastewaterTreatment Facility and the Narragansett Bay Commission’s 

facility at Bucklin Point in East Providence. 

The town of Warren is on the northern part of the 

Narragansett Bay in eastern Rhode Island (fig. 1). The total 

land area is 6.120 mi2 (table 3), of which about 27 percent 

is in the Palmer River 12-digit WBD cataloging unit, about 

13 percent is in the Barrington and Warren Rivers 12-digit 

WBD cataloging unit, and about 60 percent is in the Mount 

Hope Bay 12-digit WBD cataloging unit. The estimated total 

town population for the study period was 11,369 (table 1). 

Wastewater is collected in the town by the Warren WastewaterTreatment Facility.
14 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

NORTH

KINGSTOWN

River

Providence River

Pettaquamscutt River

Taunton River

Sakonnet River

N

A

R

R

A

G

A

N

S

E

T

T

B

A

Y

RHODE ISLAND SOUND

B U Z Z A R D S B A Y

MOUNT

HOPE

BAY

GREENWICH

 BAY

TIW-274

LTW-142

POW-551

NARRAGANSETT

NEWPORT

JAMESTOWN

MIDDLETOWN

LITTLE

COMPTON

PORTSMOUTH

TIVERTON WESTPORT

DARTMOUTH

BRISTOL

FALL RIVER

FREETOWN

DIGHTON BERKLEY

LAKEVILLE

REHOBOTH

PAWTUCKET

EAST

PROVIDENCE

PROVIDENCE

SEEKONK

SWANSEA

WARREN

BARRINGTON

SOMERSET

WARWICK

WARWICK

PORTSMOUTH

195

95

138

AQUIDNECK

ISLAND

CONANICUT

ISLAND

PRUDENCE

ISLAND

PATIENCE

ISLAND

HOG

ISLAND

EXPLANATION

Sand and gravel

Till and bedrock

Community well

U.S. Geological

 Survey well

 and identifier

TIW-274

Study-area regions

 Northeastern

 Southeastern

 East Narragansett Islands

Base map from U.S. Geological Survey, 1983, 1:24,000

Polyconic projection, (NAD 83)

71o15'

41o

30'

41o

45'

71o

5 MILES

5 KILOMETERS

0

0

2.5

RHODE ISLAND

MASSACHUSETTS

East Passage

Figure 5. Surficial geology and selected withdrawal wells for the regions in the East Narragansett Bay study area, 

eastern Rhode Island, 1995–99.
Introduction 15

Southeastern Narragansett Region

The Southeastern Narragansett region (52.05 mi2) is 

in the southeastern section of the East Narragansett Bay in 

Rhode Island. The towns in the region include Little Compton and Tiverton (fig. 1). Land areas and land-use areas by 

category are summarized in tables 3 and 4. There are several 

small brooks that drain into the Atlantic Ocean from Little 

Compton—Adamsville Brook, Cold Brook, Sisson Brook, 

Dundery Brook, as well as some unnamed brooks. In Tiverton, 

there are a few small brooks that drain into what is referred to 

as the Sakonnet River, which is the area in Narragansett Bay 

between Aquidneck Island and the towns of Little Compton 

and Tiverton. About 8 percent of the region is thin (less than 

40 ft thick) stratified sand and gravel deposits (fig. 5). There is 

one discontinued stream-gaging stations in the region (fig. 4), 

Adamsville Brook at Adamsville, Rhode Island (station 

01106000), where the USGS collected surface-water data from 

1940 through 1987.

The town of Little Compton is on the southern part of the 

southeastern Narragansett Bay (fig. 1). The total land area is 

22.05 mi2 (table 3), of which about 3 percent is in the Westport River-Noquochoke Lake to mouth 12-digit WBD cataloging unit, about 64 percent is in the Rhode Island SoundRichmond Pond to Sakonnet Point 12-digit WBD cataloging 

unit, and about 33 percent is in the Sakonnet River 12-digit 

WBD cataloging unit. The estimated total town population for 

the study period was 3,343 (table 1). There are no major water 

suppliers in the town, and no wastewater-treatment facilities.

The town of Tiverton is on the northern part of the 

southeastern Narragansett Bay in Rhode Island (fig. 1). The 

total land area is 30.00 mi2 (table 3), of which about 20 

percent is in the Westport River-Noquochoke Lake to mouth 

12-digit WBD cataloging unit, about 2 percent is in the Rhode 

Island Sound-Richmond Pond to Sakonnet Point 12-digit 

WBD cataloging unit, about 20 percent is in the Quequechan 

River 12-digit WBD cataloging unit, about 7 percent is in the 

Mount Hope Bay 12-digit WBD cataloging unit, and about 

51 percent is in the Sakonnet River 12-digit WBD cataloging 

unit. The estimated town population for the study period was 

14,194 (table 1). There are three major public water suppliers 

in Tiverton: the North Tiverton Fire District, the Stone Bridge 

Fire District, and the Tiverton Fire District. Three minor public water suppliers serve small populations in the town.

East Narragansett Islands Region

The East Narragansett Islands region (41.05 mi2) is in the 

center of Narragansett Bay in Rhode Island. The towns in the 

region include Middletown, Newport, and Portsmouth (fig. 1). 

Land areas and land-use areas by category are summarized in 

tables 3 and 4. The region area has minimal sand and gravel 

deposits that compose about 5 percent of the total glacial 

deposits (fig. 5). Because the glacial deposits on the islands 

are thin and the area is flat, small brooks drain into the East 

Passage that runs between Aquidneck and Prudence and 

Conanicut Islands and into the Sakonnet River along the east 

side of Aquidneck Island. 

The city of Newport is on the southern part of Aquidneck 

Island in the eastern part of Narragansett Bay in Rhode 

Island (fig. 1). The city includes Goat Island, Rose Island, 

and Coasters Harbor Island, which are in the center of 

Narragansett Bay in Rhode Island. Forty-seven percent of the 

city’s land area is in the Lower East Passage 12-digit WBD 

cataloging unit, and 53 percent is in the Coastal Aquidneck 

12-digit WBD cataloging unit. The total land area is 7.445 mi2

(table 3). The estimated total population for the study period 

was 24,536 (table 1). The Newport Water Works supplies the 

city’s public water, and the Newport Wastewater-Treatment 

Facility serves the city for the collection of wastewater. The 

service area includes one retail customer, the U.S. Navy, 

which is on Coasters Harbor Island in the East Passage. 

Portsmouth occupies the northern part of Aquidneck 

Island, and the town includes Patience Island, Prudence Island, 

Hope Island, and Hog Island, which are in the center of Narragansett Bay in Rhode Island (fig. 1). The total land area is 

21.10 mi2 (table 3), of which 6 percent is in the Mount Hope 

Bay12-digit HUC, 60 percent is in the Upper West Passage, 

Upper East Passage, and Lower East Passage 12-digit WBD 

cataloging units, 33 percent is in the Sakonnet River 12-digit 

WBD cataloging unit, and 1 percent is in the Coastal Aquidneck 12-digit WBD cataloging unit. The estimated town population for the study period was 16,721 (table 1). The area of 

Portsmouth on Aquidneck Island is served by the Portsmouth 

Water and Fire District and the Newport Water Works’s public 

water-supply systems (table 4). The only other area with a 

service area and resource for public supply is on Prudence 

Island, where the Prudence Island Utility, a minor public water 

supplier, serves residents and commercial customers for this 

part of Portsmouth. 

Middletown is between Newport and Portsmouth on 

Aquidneck Island. The total land area is 12.50 mi2 (table 3), of 

which 18 percent is in the Lower East Passage 12-digit WBD 

cataloging unit, 43 percent is in the Sakonnet 12-digit WBD 

cataloging unit, and 39 percent is in the Coastal Aquidneck 

12-digit WBD cataloging unit. The estimated population for 

the study period was 18,970 (table 1). Middletown is served 

by the Portsmouth Water and Fire District and the Newport 

Water Works’ public water-supply systems (table 4), and the 

Newport Wastewater-Treatment Facility serves the town for 

the collection of wastewater. One minor public water supplier 

serves a small population.
16 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Water Use

The data for the water-use components for the East 

Narragansett Bay study area were organized by using 

NEWUDS. Components of water use include water 

withdrawals, public-supply systems and distributions, 

nonaccount use, water use by category, consumptive water use, 

wastewater-system collections, and return flow (fig. 3). For 

the study period, data were categorized as either public-supply 

withdrawals from ground-water and surface-water systems 

or self-supply withdrawals from the ground-water system 

(fig. 6). Conveyance losses are an example of nonaccount 

water use (which is unmetered) in public-supply systems, and 

include leaks, system flushing, and fire-hydrant use within the 

systems. The nonaccount water use for a public-supply system 

is the total distribution minus the public-supply distributions 

for the water-use categories in the system. Water-use 

categories used in this report are domestic, commercial, 

industrial, and agricultural for public-supply and self-supply 

users (fig. 7). Consumptive water use refers to water removed 

from the environment through uses by humans, livestock, 

production, or evapotranspiration. Wastewater from local and 

regional public-wastewater systems is returned to a surfacewater body. Return flow to ground water or surface water 

includes site-specific permitted discharges and aggregate 

discharges from septic systems, which were assessed by town 

and region for the study area (fig. 8). Water withdrawals, water 

use, consumptive use, and return flow were calculated for each 

region by town for the calendar years during the study period. 

Analyses of the data indicated that more than 50 percent 

of the total water use was from surface-water withdrawals 

(16 percent) and wholesale water purchases (38 percent) from 

outside the basin; these were the predominant water sources 

for public suppliers in the study area during the study period 

from 1995 through 1999. 

0

1

2

3

4

5

6

7

WITHDRAWAL CATEGORY

MILLION GALLONS PER DAY

Northeastern Narragansett Bay region

Southeastern Narragansett Bay region

East Narragansett Islands region

PUBLIC DOMESTIC

SELF

INDUSTRIAL

SELF

COMMERCIAL

SELF

AGRICULTURAL

SELF

Figure 6. Public-supply withdrawals, and self-supply domestic, commercial, industrial, and agricultural 

withdrawals for the regions in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.
Water Use 17

0

1

2

3

4

5

6

7

SUPPLY CATEGORY

MILLION GALLONS PER DAY

Northeastern Narragansett Bay region

Southeastern Narragansett Bay region

East Narragansett Islands region

DOMESTIC COMMERCIAL INDUSTRIAL AGRICULTURAL

PUBLIC SELF PUBLIC SELF PUBLIC SELF PUBLIC SELF

0

1

2

3

4

5

6

7

DISPOSAL CATEGORY

MILLION GALLONS PER DAY

Northeastern Narragansett Bay region

Southeastern Narragansett Bay region

East Narragansett Islands region

DOMESTIC COMMERCIAL INDUSTRIAL

PUBLIC SELF PUBLIC SELF PUBLIC SELF

Figure 7. Public-supply and self-supply domestic, commercial, industrial, and agricultural water use for the regions 

in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.

Figure 8. Wastewater-treatment facilities, Rhode Island Pollutant Discharge Elimination 

System, and self-disposed domestic, commercial, and industrial water return flow for the 

regions in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.
18 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

New England Water-Use Data System

The NEWUDS database was used as a tool to track the 

water withdrawn and used in the East Narragansett Bay study 

area. The database was queried to obtain the average water 

use for the study period, and the results of the analyses are 

in the tables and figures of this report. The data entered into 

the NEWUDS database consist of site-specific and aggregate 

water withdrawals, uses, and discharges. When available, 

monthly, quarterly, and (or) yearly metered (or reported) data 

were entered into the database, and were converted to common 

units (Mgal/d) for comparison. Unmetered water withdrawals, 

uses, and discharges were estimated, by category, by means 

of previously published methods (Wild and Nimiroski, 2004). 

Documentation describing database development and how to 

use the database are presented in the reports by Tessler (2002) 

and Horn (2003), respectively.

Public Water Supply and Potable-Water 

Interbasin Transfers

Public water suppliers were categorized as two types: 

major public suppliers that have a system of distribution (fig. 

9) and minor suppliers that have closed systems. Three major 

public water suppliers withdraw water from the study area: 

Bristol County Water Authority, Stone Bridge Fire District, 

and the Newport Water Works (table 7). Seven major public 

water suppliers, however, serve the study area: Bristol County 

Water Authority, East Providence Water Department, North 

Tiverton Fire District, Stone Bridge Fire District, Tiverton Fire 

District, Newport Water Works, and the Portsmouth Water 

and Fire District, which supply the domestic, commercial, 

industrial, and agricultural sectors (table 8). Five minor public 

water suppliers serve small public populations, such as nursing 

homes, condominium associations, and mobile home parks 

(table 9). The total withdrawals from public water supplies by 

town and region are summarized in table 10. 

For the purpose of this study, potable interbasin transfer 

is water that is conveyed from public water suppliers across 

hydrologic divides or boundaries separating defined study 

areas. The water is an import, or a gain to the basin or region, 

if the water is withdrawn in another basin or region and used 

within the study area. The water is an export, or a loss to the 

basin or region if the water is withdrawn within the study area, 

but used in another basin or defined study area.

The Bristol County Water Authority supplies the 

domestic, industrial, commercial, and agricultural water 

users in the towns of Barrington, Bristol, and Warren. 

The water-supply system for this study includes well 

withdrawals, wholesale purchases from the East Providence 

Water Department, the Providence Water Supply Board, 

and reservoir withdrawals imported to Rhode Island from 

Massachusetts (table 8). The average withdrawals for the 

study period were 0.576 Mgal/d from the Nayatt well field 

in Barrington; however, withdrawals from this well field 

have ceased since the study period. Wholesale water totals 

of 0.280 Mgal/d and 0.311 Mgal/d were purchased from the 

East Providence Water Department and the Providence Water 

Supply Board, respectively (table 8); however, currently 

(2004), the only purchases were from the Providence Water 

Supply Board. A total of 2.618 Mgal/d of surface water 

was imported from the Massachusetts reservoirs; however, 

currently (2004), the Bristol County Water Authority does 

not import water from the Warren Reservoir in Swansea, 

Massachusetts. The Bristol County Water Authority made 

53 percent of the total withdrawals in the region and 6 percent 

of the total withdrawals in the East Narragansett Bay study 

area. The water withdrawals, purchases, and estimated 

distributions are summarized in figure 10.
Water Use 19

Providence River

Pettaquamscutt River

Taunton River Sakonnet River

N

A

R

R

A

G

A

N

S

E

T

T

B A

Y

RHODE ISLAND SOUND

B U Z Z A R D S B A Y

MOUNT

HOPE

GREENWICH BAY

 BAY

Stafford

Pond

NORTH

KINGSTOWN

NARRAGANSETT

NEWPORT

JAMESTOWN

MIDDLETOWN

LITTLE

COMPTON

PORTSMOUTH

PORTSMOUTH TIVERTON

WESTPORT

DARTMOUTH

BRISTOL

FALL RIVER

FREETOWN

BERKLEY

DIGHTON

REHOBOTH

PAWTUCKET

EAST

PROVIDENCE

PROVIDENCE

SEEKONK

SWANSEA

WARREN

BARRINGTON

SOMERSET

WARWICK

WARWICK

AQUIDNECK

ISLAND

CONANICUT

ISLAND

PRUDENCE

ISLAND

PATIENCE

ISLAND

HOG

ISLAND

95

195

138

Tiverton

Fire

District

East

 Providence

Water

Department

Bristol

County

Water

Authority

Portsmouth

Water and

Fire

District

Newport

Water

Works

North

Tiverton

Fire

District

Stone Bridge

Fire District

Base map from U.S. Geological Survey, 1983, 1:24,000

Polyconic projection, NAD 83

71o15'

41o30'

41o

45'

71o

5 MILES

5 KILOMETERS

0

0

2.5

Lawton Valley

Reservoir

Sisson

Pond

Green

End

Pond

Easton

Pond

Anawan

 Reservoir

Shad

Factory

Pond

Swansea

Reservoir

Kickemuit 

Reservoir North

Watuppa 

Pond

St. Mary's

Pond

Nonquit

Pond

Harold E.

Watson

Reservoir

Gardiner

Pond

Nelson

Pond

EXPLANATION

Study-area regions

 Northeastern

 Southeastern

 East Narragansett Islands

RHODE ISLAND

MASSACHUSETTS

Figure 9. Rhode Island water-supply districts in the East Narragansett Bay study area, 1995–99.
20 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Table 7. Public-supply withdrawals in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.

[All towns/cities assumed to be in Rhode Island unless otherwise noted. Mgal, million gallons; Mgal/d, million gallons per day; --, not applicable or data not 

available].

Source City/town

Reservoir characteristics Water

 withdrawals 

1995-99

(Mgal/d)

Safe yield 

(Mgal/d)

Drainage 

area

(mi2)

Surface area 

(mi2)

Storage 

capacity 

(Mgal)

Bristol County Water Authority

Nayatt well field Barrington -- -- -- -- 0.576

Stone Bridge Fire District

Stafford Pond1 Tiverton 1.90 2.10 0.761 16,000 0.976

Newport Water Works

Watson Reservoir2 Little Compton (small part in 

Tiverton)

 -- 3.7 0.131 1,600 --

Nonquit Pond3 Tiverton -- 6.0 .278 562 --

St. Mary’s Pond4 Portsmouth -- .80 .181 245 --

Lawton Valley Reservoir5 Portsmouth -- 1.1 .131 328 --

Sisson Pond6 Portsmouth -- .4 .141 122 --

North and South Easton 

Ponds7

Middletown-Newport line -- 3.75 .402 645 --

Nelson and Gardiner Ponds8 Middletown -- 2.88 .205 377 --

Intake from North and South 

Easton Ponds1

Newport -- -- -- -- 1.949

Lawton Valley Reservoir 

intake5 Portsmouth -- -- -- -- 4.100

Total for Newport Water Works 12.2 18.63 1.924 3,879 6.049

Study-area total 14.10 20.73 2.685 19,879 7.601

1 Stafford Pond safe yield is determined by the City of Fall River’s Watuppa Water Supply Board in Massachusetts.

2 Watson Reservoir is used for storage only, and the usable storage is 1,300 Mgal.

3 Nonquit Pond usable storage is 400 Mgal.

4 St. Mary’s Pond usable storage is 240 Mgal.

5 Lawton Valley Reservoir usable storage is 315 Mgal.

6 Sisson Pond usable storage is 111 Mgal.

7 North and South Easton Ponds usable storage is 527 Mgal.

8 Nelson and Gardiner Ponds usable storage is 353 Mgal.
Water Use 21

Table 9. Minor public suppliers by region in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.

[Coefficient used for minor-supplier population is 67 gal/d/person. All wells are completed in bedrock. Gal/d/person, gallons per day per person; Mgal/d, 

million gallons per day, --, not applicable]

Minor supplier Town

Estimated 1995-99 

Population Water withdrawals and use

 (Mgal/d)

Northeastern Narragansett region

-- -- -- --

Southeastern Narragansett region

Four Seasons Mobile Home Park Tiverton 41 0.003

Heritage Park Tiverton 75 .005

Lawrence Sunset Cove Association Tiverton 39 .003

Total 155 0.011

East Narragansett Islands region

Meadowlark Mobile Home Park Middletown 175 0.012

Prudence Island Utility Corporation Portsmouth (Prudence Island) 600 .040

Total 775 0.052

Study-area total 930 0.063

Table 8. Public water-supply imports and wholesale purchases to the East Narragansett Bay study area, eastern 

Rhode Island, 1995–99.

[All towns/cities assumed to be in Rhode Island unless otherwise noted. Mgal/d, million gallons per day; --, not applicable or data not available]

Water supplier Wholesale water

supplier City/town Description and location of withdrawal source

Imports and(or) wholesale 

purchases 1995-99

(Mgal/d)

Bristol County Water 

Authority1

-- Warren Warren Reservoir, Swansea, 

Massachusetts

2.618

Providence Water Supply 

Board

Scituate Regional distribution from the 

Scituate Reservoir

.311

East Providence Water 

Department

-- Purchase from Providence 

Water Supply Board

.280

East Providence Water 

Department

Providence Water Supply 

Board

-- Purchase from Providence 

Water Supply Board

5.484

North Tiverton Fire District Fall River Water DepartmentFall River, 

Massachusetts

North Watuppa and Copicut 

Reservoirs

.200

Stone Bridge Fire District Tiverton Stafford Pond .134

Portsmouth Water and Fire 

District

Newport Water Works Portsmouth Lawton Valley Reservoir .584

Stone Bridge Fire District Tiverton Stafford Pond .437

Tiverton Fire District2 Stone Bridge Fire District Tiverton Stafford Pond .035

1 Bristol County Water Authority currently (2004) does not use the reservoir for supply. Water is purchased wholesale from the Providence Water 

Supply Board.

2 The North Tiverton Fire District currently (2004) operates the Tiverton system.
22 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Table 10. Ground-water and surface-water withdrawals by town and region in the East Narragansett Bay study area, eastern Rhode 

Island, 1995–99. 

[Public-supply domestic, commercial, and industrial water withdrawals are from ground water (wells). Irrigation-water withdrawals (in the agricultural category) are assumed to be 81 percent from surface water (ponds and rivers) and 13 percent from ground water (wells). Livestock water withdrawals are assumed 

to be 9 percent from surface water and 82 percent from ground water. The remaining 6 percent for irrigation and 9 percent for livestock are estimated to be 

from public supply (Soil Conservation Service, 1993). All values are in Mgal/d, million gallons per day; --, not applicable; <0.001, value not included in totals.]

City/Town Public-supply 

withdrawals

Self-supply withdrawals

Total

Domestic Commercial Industrial Agricultural

 Northeastern Narragansett region

Barrington 0.576 0.058 -- -- 0.022 0.656

Bristol -- .221 -- -- .015 .236

East Providence -- .008 -- -- .062 .070

Warren -- .108 0.001 0.002 .009 .120

Region total 0.576 0.395 0.001 0.002 0.108 1.082

Southeastern Narragansett region

Little Compton -- 0.231 <0.001 0.003 0.046 0.277

Tiverton 0.987 .404 .002 -- .019 1.412

Region total 0.987 0.635 0.002 0.003 0.065 1.692

East Narragansett Islands region

Middletown 0.012 0.222 0.013 0.031 0.036 0.314

Newport 1.949 <.001 .047 .023 .021 2.040

Portsmouth 4.140 .043 <.001 .154 .090 4.427

Region total 6.101 0.265 0.060 0.208 0.147 6.781

Study-area total 7.664 1.295 0.063 0.213 0.320 9.555
Water Use 23

Domestic

2.244 Mgal/d

Commercial

0.926 Mgal/d

Retail distribution

Nonaccount use

Wholesale

Purchases, withdrawals,

 return flows, and distribution

EXPLANATION

Transfers to and from study area

Transfers within study area

Nayatt Well

Field

(Barrington, RI)

0.576 Mgal/d

Warren Reservoir

(Swansea,

Massachusetts)

2.618 Mgal/d

East Providence

Water Department

0.280 Mgal/d

Providence

Water Supply

Board

0.311 Mgal/d

Nonaccount

0.508 Mgal/d

Bristol County Water Authority

Distribution

3.785 Mgal/d

Industrial

0.107 Mgal/d

TOTAL 3.277

Figure 10. Bristol County Water Authority withdrawals, imports, treatment, distributions, and estimated water 

uses in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.
24 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

The East Providence Water Department system only 

purchases water (they do not withdraw water) from the 

Providence Water Supply Board’s Scituate Reservoir in the 

Pawtuxet River Basin. The East Providence supply system 

purchased an average of 5.484 Mgal/d during the study 

period (table 8). As previously discussed, the East Providence 

Water Department sold water to the Bristol County Water 

Authority during the study period. The purchases, wholesales, 

and estimated distributions for the East Providence Water 

Department system are summarized in figure 11.

The North Tiverton Fire District purchased about 

0.200 Mgal/d of water from the Fall River Water Department 

(Watuppa Water Board) as an import to the state and study 

area; and the district purchased about 0.134 Mgal/d of water 

from the Stone Bridge Fire District in Tiverton, Rhode Island 

(table 8). During the study period, the Tiverton Fire District 

served a small area in the study area and purchased about 

0.035 Mgal/d from the Stone Bridge Fire District. Currently, 

however, the Tiverton Fire District’s is operated by the North 

Tiverton Fire District (table 8). The North Tiverton Fire 

District’s wholesale purchases and estimated distributions are 

summarized in figure 12. 

The Stone Bridge Fire District withdrew an average of 

0.976 Mgal/d during the study period from Stafford Pond in 

Tiverton (table 7). As previously discussed, the Stone Bridge 

Fire District sells water wholesale to the North Tiverton Fire 

District and the Tiverton Fire District. In addition, the Stone 

Bridge Fire District sells water to the Portsmouth Water and 

Fire District on Aquidneck Island. The Stone Bridge Fire 

District withdrew 58 percent of its total withdrawals in the 

Southeastern Narragansett region and 10 percent in the study 

area. The surface-water withdrawals and distributions are 

summarized in figure 13.

The largest major water supplier in the East Narragansett 

Bay study area is the Newport Water Works in the East 

Narragansett Islands region. This supplier withdrew an 

average of 6.049 Mgal/d during the study period from a 

series of nine surface-water reservoirs (table 7). About 

0.584 Mgal/d was sold wholesale to the Portsmouth Water and 

Fire District (table 8). The Newport Water Works withdrew 

89 percent of its total withdrawals in the East Narragansett 

Islands region and 63 percent of the total withdrawals in the 

East Narragansett Bay study area. The water withdrawals, 

distributions, and use are summarized in figure 14 for the 

Newport Water Works. 

Five minor public water suppliers serve the East 

Narragansett Bay study area (table 9). Limited data are 

available on these water withdrawals; therefore, water use 

was estimated by applying the water-use coefficient for public 

water supply (67 gal/d/person in Rhode Island) determined by 

Korzendorfer and Horn (1995) to the estimated population on 

public water. The total of the estimated water withdrawn in the 

study area by minor suppliers was 0.063 Mgal/d. Estimated 

water withdrawals for the regions were 0.011 Mgal/d in the 

Southeastern Narragansett region and 0.052 Mgal/d in the East 

Narragansett Islands region; no minor public water suppliers 

were in the Northeastern Narragansett region. Estimated water 

withdrawals for the individual minor suppliers ranged from 

0.003 Mgal/d to 0.040 Mgal/d. 
Water Use 25

Nonaccount use

0.505 Mgal/d

Domestic

3.392 Mgal/d

Commercial

1.139 Mgal/d

Retail distribution

Nonaccount use

Wholesale

EXPLANATION

Transfers to and from study area

Transfers within study area

Providence

Water Supply

Board

5.484 Mgal/d

Bristol County

Water Authority

0.280 Mgal/d

East Providence Water 

Department

Distribution

4.699 Mgal/d

TOTAL 4.699

Industrial

0.168 Mgal/d

Purchases, withdrawals,

 return flows, and distribution

Figure 11. East Providence Water District imports, wholesale purchases, distributions, and estimated water 

uses in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.
26 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Nonaccount use

0.026 Mgal/d

Domestic

0.289 Mgal/d

Commercial

0.011 Mgal/d

Industrial

0.000 Mgal/d

EXPLANATION

Transfers to and from study area

Transfers within study area

TOTAL 0.300

Retail distribution

Nonaccount use

Wholesale

Stone Bridge

Fire District

 0.134 Mgal/d

Nonaccount use

0.008 Mgal/d

North Tiverton Fire District

Distribution

0.326 Mgal/d

Fall River Water

Department

0.200 Mgal/d

Purchases, withdrawals,

 return flows, and distribution

Figure 12. North Tiverton Fire District imports, wholesale purchases, distributions, and estimated water uses in the 

East Narragansett Bay study area, eastern Rhode Island, 1995–99.
Water Use 27

Domestic

0.148 Mgal/d Nonaccount use

0.003 Mgal/d Commercial

0.015 Mgal/d

Nonaccount use

0.138 Mgal/d

Industrial

<0.001 Mgal/d

0.005 Mgal/d

Retail distribution

Nonaccount use

Wholesale

Purchases, withdrawals,

 return flows, and distribution

EXPLANATION

Transfers to and from study area

Transfers within study area

Governmental

TOTAL 0.168

Portsmouth

Water and

Fire District

0.437 Mgal/d

Tiverton Fire 

District 

0.035 Mgal/d

North Tiverton

Fire District

0.134 Mgal/d

Internal use

0.061 Mgal/d Withdrawal from

Stafford Pond

0.976 Mgal/d

East Providence 

Water Department

0.280 Mgal/d

Stone Bridge 

Fire District

Distribution

0.838 Mgal/d

< Less than

Figure 13. Stone Bridge Fire District withdrawals, distributions, and estimated water uses in the East Narragansett Bay 

study area, 1995–99.
28 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

North and South

Easton Ponds

1.949 Mgal/d

Lawton Valley

Reservoir

Intake

4.100 Mgal/d

Portsmouth

Water and 

Fire District

0.584 Mgal/d

Domestic

2.014 Mgal/d

Commercial

1.566 Mgal/d

U.S. Navy

(Commercial

Use)

1.242 Mgal/d

Nonaccount

0.643 Mgal/d

Newport Water Works

Distribution

6.049 Mgal/d

Retail distribution

Nonaccount use

Wholesale

Purchases, withdrawals,

return flows, and distribution

EXPLANATION

Transfers to and from study area

Transfers within study area

TOTAL 4.822

Figure 14. Newport Water Works withdrawals, distributions, and estimated water uses in the East Narragansett 

Bay study area and basin exports, 1995–99.
Water Use 29

Domestic Water Use

Domestic water use is the amount of water used by 

residential populations served either by public supplies or 

by private wells. To calculate the water use for this category, 

population estimates in Rhode Island were multiplied by the 

water-use coefficients 71 gal/d/person for self-supply domestic 

water use and 67 gal/d/person for public-supply domestic 

water use; these coefficients were based on the 1990 National 

water-use compilation (Korzendorfer and Horn, 1995). 

Public-Supply Use

Region populations on public supply were estimated 

by merging the 1990 census-block coverages, which include 

information about the domestic populations on private 

wells, with the town coverages obtained from RIGIS. The 

ratios of 1990 self- and public-supply populations to the 

total 1990 populations were multiplied by the average 

population in the study area for 1995–99 to give the selfand public-supply population for 1995–99 (table1). When 

domestic water-use data (listed as residential in the WaterSupply Management Plans) were available, the domestic 

data were used instead of a calculation based on ratios. 

Because limited withdrawal data are available for the five 

minor public water suppliers in the study area, the wateruse coefficient for domestic public water supply was 

applied to populations served by each minor supplier. 

Public-supply domestic water use was 5.636 Mgal/d in 

the Northeastern Narragansett region; 0.576 Mgal/d in the 

Southeastern Narragansett region; and 3.211 Mgal/d in the 

East Narragansett Islands region for this water-use category. 

The estimated domestic use of public-supply water by town 

and region is listed in table 11 and illustrated in figure 7.

Self-Supply Use

The average population from 1995 through 1999 that 

withdrew self-supply water for each region was estimated 

from the 1990 population and from the ratio of growth for 

1995 through 1999 within each region (table 1). Domestic 

water withdrawals and uses in the regions were 0.395 Mgal/d 

in the Northeastern Narragansett region, 0.635 Mgal/d in the 

Southeastern Narragansett region, and 0.265 Mgal/d in the 

East Narragansett Islands region for this water-use category 

(figs. 6 and 7, tables 10 and 11). 

Commercial and Industrial Water Use

Limited data are available on commercial and industrial 

water use from public- and self-supply systems because 

withdrawals and use for these water-use categories (figs. 6 

and 7) are not regulated in Rhode Island unless the withdrawal 

point is adjacent to a wetland (Rhode Island Department 

of Environmental Management, 2001). Commercial and 

industrial water-use estimates, therefore, were derived from 

the total calculated water use and apportioned for each town 

by the land-use type and water-supply district. Commercial 

and industrial consumptive water use (table 12) is assumed to 

be 10 percent of the total water use (Solley and others, 1998).

Public-Supply Use

Information on the delivery of water to commercial and 

industrial users of public-supply water included metered (or 

reported) and unmetered water-use data. When the data were 

available, the public suppliers provided the delivery volume 

and the number of service connections for commercial and 

industrial water users. In some cases, the suppliers reported 

the commercial and industrial uses together, and in other cases 

the information was not available. Government water use 

is accounted for within the commercial water-use category 

according to the Standard Industrial Classification (SIC) 

codes. For this study, government water use was entered as a 

separate distribution into NEWUDS if the supplier collected 

the data to this level of detail. Because some water-supply 

districts serve one or more towns and regions, the public 

commercial and industrial water uses were apportioned 

by percentages of the land-use areas (table 4). Land-use 

coverages from RIGIS were merged with the water-supply and 

town coverages to obtain the percentage of commercial and 

industrial land use within the supply districts for towns served 

in the East Narragansett Bay study area. Commercial use of 

public-supply water was 2.065 Mgal/d in the Northeastern 

Narragansett region; 0.007 Mgal/d in the Southeastern 

Narragansett region; and 2.820 Mgal/d in the East 

Narragansett Islands region. Industrial use of public-supply 

water was 0.275 Mgal/d in the Northeastern Narragansett 

region; 0.001 Mgal/d in the Southeastern Narragansett 

region. This water-use category was not applicable in the East 

Narragansett Islands region during the period of study. 
30 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Table 11. Estimated water use by town and region in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.

[Mgal/d, million gallons per day; --, not applicable; <0.001, value not included in totals]

City/Town

Domestic supply 

(Mgal/d)

Commercial supply 

(Mgal/d)

Industrial supply

(Mgal/d)

Agricultural supply 

(Mgal/d)

Total water 

use

Public Self Public Self Public Self Public Self (Mgal/d)

 Northeastern Narragansett region

Barrington 1.035 0.058 0.240 -- 0.006 -- -- 0.022 1.361

Bristol .856 .221 .365 -- .060 -- -- .015 1.517

East Providence 3.392 .008 1.139 -- .168 -- -- .062 4.769

Warren .353 .108 .321 0.001 .041 0.002 -- .009 .835

Region total 5.636 0.395 2.065 0.001 0.275 0.002 -- 0.108 8.482

Southeastern Narragansett region

Little Compton 0.006 0.231 -- <0.001 -- 0.003 -- 0.046 0.286

Tiverton .570 .404 0.007 .002 0.001 -- -- .019 1.003

Region total 0.576 0.635 0.007 0.002 0.001 0.003 -- 0.065 1.289

East Narragansett Islands region

Middletown 1.061 0.222 0.994 0.013 -- 0.031 -- 0.036 2.357

Newport 1.070 <.001 1.770 .047 -- .023 -- .021 2.931

Portsmouth 1.080 .043 .056 <.001 -- .154 -- .090 1.423

Region total 3.211 0.265 2.820 0.060 -- 0.208 -- 0.147 6.711

Study-area total 9.423 1.295 4.892 0.063 0.276 0.213 -- 0.320 16.48

Table 12. Consumptive water use by town and region in the East Narragansett Bay study area, eastern Rhode Island, 1995–99.

[All values are in Mgal/d, million gallons per day. --, not applicable; <0.001, value not included in totals] 

City/town

Domestic Commercial Industrial Agricultural Total consumptive 

water use Public Self Public Self Public Self Public Self

 Northeastern Narragansett region

Barrington 0.155 0.009 0.002 -- 0.001 -- -- 0.022 0.189

Bristol .128 .033 .036 -- .006 -- -- .015 .218

East Providence .509 .001 .114 -- .017 -- -- .062 .703

Warren .053 .016 .032 <0.001 .004 <0.001 -- .009 .114

Region total 0.845 0.059 0.184 <0.001 0.028 <0.001 -- 0.108 1.224

Southeastern Narragansett region

Little Compton 0.001 0.035 -- -- -- <0.001 -- 0.046 0.082

Tiverton .086 .061 0.001 <0.001 <0.001 -- -- .019 .167

Region total 0.087 0.096 0.001 <0.001 <0.001 <0.001 -- 0.065 0.249

East Narragansett Islands region

Middletown 0.159 0.033 0.099 0.001 -- 0.003 -- 0.036 0.331

Newport .161 <.001 .177 .005 -- .002 -- .021 .366

Portsmouth .162 .006 .006 -- -- .015 -- .090 .279

Region total 0.482 0.039 0.282 0.006 -- 0.020 -- 0.147 0.976

Study-area total 1.414 0.194 0.467 0.006 0.028 0.020 -- 0.320 2.449
Water Use 31

Self-Supply Use

Self-supply commercial and industrial water-use 

estimates were calculated from the employee counts published 

in the RIEDC’s “Export/Import Directory” (2000a), “High 

Tech Industries in Rhode Island” (1999), and “Major 

Employers in Rhode Island” (2000b). The number of 

employees in the industrial and commercial sectors for each 

Standard Industrial Classification (SIC) code were multiplied 

by the U.S. Army Corp of Engineers’ Institute for Water 

Resources Municipal and Industrial Needs (IWR-MAIN) 

water-use coefficient (in gal/d/person) for each town (table 13) 

as described in Horn (2000). The estimated use by commercial 

and industrial facilities on public water were subtracted from 

the total aggregate use to obtain the estimated total selfsupply use for these categories. The results for commercial 

and industrial withdrawals and use are listed in tables 10 and 

11. Commercial use of self-supply water was 0.001 Mgal/d 

in the Northeastern Narragansett region; 0.002 Mgal/d in the 

Southeastern Narragansett region; and 0.060 Mgal/d in the 

East Narragansett Islands region (figs. 6 and 7). Industrial 

use of self-supply water in the East Narragansett Bay study 

area was 0.002 Mgal/d in the Northeastern Narragansett 

region; 0.003 Mgal/d in the Southeastern Narragansett region; 

and 0.208 Mgal/d in the East Narragansett Islands region. 

Commercial and industrial water use by region and town are 

listed in table 11.

Agricultural Water Use

The estimated agricultural water use (livestock, crop 

irrigation, and golf-course irrigation) for each town was 

obtained from information provided by the U.S. Department 

of Agriculture (USDA) NRCS, formerly the Soil Conservation 

Service (SCS). Nine percent of withdrawals and use for 

livestock were assumed to be from surface water (streams 

and ponds) and 82 percent from ground water (wells); these 

livestock water-use rates were previously estimated in a 

study completed by the SCS (1993). Likewise, eighty-one 

percent of withdrawals and use for irrigation (golf courses and 

crops) were assumed to be from surface water and 13 percent 

from ground water (Soil Conservation Service, 1993). The 

remaining 9 percent of livestock use and 6 percent of irrigation 

use were assumed to be from public-supply distributions. 

The water-use coefficients for each type of livestock 

(Laura Medalie, U.S. Geological Survey, written commun., 

1995) were multiplied by the number of livestock of each type. 

Because the livestock and crop-irrigation data are reported 

in the 1997 Census of Agriculture for the county level (U.S. 

Department of Agriculture, 1997a, b), the estimates were 

disaggregated on the basis of the number of farms in the town 

and the percentage of agricultural land use by town. The 

livestock water-use estimates represent a year-round usage. 

Although it is estimated that 60 percent of livestock water use 

is consumptive and 40 percent is returned to ground water 

(Horn and others, 1994), this distinction was negligible for 

each town in the East Narragansett Bay study area. Thus, 

agricultural water was assumed to be 100 percent consumed 

(table 12) (Horn and others, 1994). Livestock water use is 

minimal in the study area, and accounted for about 6 percent 

of the agricultural water withdrawals during the summer 

and less than one percent of the annual agricultural water 

withdrawals during the study period.

The amount of water needed to irrigate crops was 

estimated for each town in the study area. Irrigated-cropland 

acreage needed to be estimated for each town because it is 

not reported at the town level; irrigated-cropland acreage 

was estimated by multiplying agricultural land-use area (in 

acres) by the ratio of cropland area to agricultural land area 

for the county in which each town is located. The amount of 

water needed to irrigate crops in each town was assumed to be 

about 1 in/week/acre (or 0.143 in/day/acre) minus the average 

monthly rainfall for the study area.

Similarly, the amount of water needed to irrigate golf 

courses was estimated for each town in the study area. This 

was done by compiling a list of golf courses for each town 

and obtaining the total yardages of each golf course from the 

Web sites WorldGolf.com (2002) and GolfCourse.com (2002). 

In turn, the amount of water used to irrigate each golf course 

was estimated by applying a previously published water-use 

coefficient of 0.0116 Mgal/d per 1,000 golf-course yards 

(Laura Medalie, U.S. Geological Survey, written commun., 

2000); this coefficient was developed by using reported golfcourse water-use data. The amount of water needed to irrigate 

golf courses for each town was determined by adding together 

the amounts of water used to irrigate all of the golf courses 

in each town. A similar water-use coefficient has been used 

by others (Wild and Nimiroski, 2004). Most notably, irrigation was done during June, July, and August; therefore, it was 

assumed that crop- and golf-course irrigation was done during 

these months (Soil Conservation Service, 1993). 

Total agricultural water use was determined for each 

town and region by adding together the amounts of water 

used for livestock, crops, and golf courses. The total 

amount of water used for this purpose was calculated to 

be about 0.108 Mgal/d in the Northeastern Narragansett 

region; 0.065 Mgal/d in the Southeastern Narragansett 

region; and 0.147 Mgal/d in the East Narragansett 

Islands region (figs. 6 and 7, tables 10 and 11). 
32 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Table 13. Estimated water use per 2-digit Standard Industrial Classification code by town in the East Narragansett Bay study area, 

eastern Rhode Island, 1995–99.

[SIC, Standard Industrial Classification; IWR-MAIN, Institute for Water Resources Municipal and Industrial Needs. IWR-MAIN coefficient is in gallons per 

day per person. gal, gallons; Mgal/d, Million gallons per day; --, not applicable; <0.001, value not used in totals]

2-digit SIC category 

and code

IWR-MAIN

coefficient

Estimated water use in city/town (Mgal/d)

Barrington Bristol East Providence

Little 

Compton

Middletown Newport Portsmouth Tiverton Warren

Industrial [20-39]

 Food [20] 469 -- 0.033 0.050 0.003 -- 0.009 -- -- 0.040

 Textile Mills [22] 315 -- .047 .002 -- 0.008 -- 0.003 -- --

 Finished apparel [23] 13 -- <.001 <.001 -- -- <.001 -- -- .001

 Wood, lumber [24] 78 -- -- -- -- -- -- -- -- --

 Furniture [25] 30 -- -- .009 -- -- -- -- -- --

 Paper Products [26] 863 -- .021 .259 -- -- -- -- -- .008

 Printing, Publishing 

[27]

42 -- <.001 .010 -- .002 -- -- -- --

 Chemical Products [28] 289 -- -- .153 -- -- -- -- -- --

 Petroleum Refining [29] 1045 -- -- -- -- -- -- -- -- --

 Rubber [30] 119 -- .034 .041 -- .001 -- -- -- .012

 Leather [31] 148 -- -- -- -- -- .001 -- -- --

 Stone, clay, glass, and 

concrete [32]

202 -- -- -- -- -- .004 -- -- --

 Primary metals [33] 178 -- .001 .006 -- -- -- -- -- --

 Fabricated metal [34] 95 -- .004 .012 -- -- -- .009 -- --

 Machinery [35] 58 -- .010 .008 -- .001 -- .001 -- .006

 Electrical equipment 

[36]

71 -- <.001 .013 -- .003 -- .010 <0.001 --

 Transportation equipment [37]63 -- .018 .035 -- .005 .007 .028 -- .019

 Instruments [38] 66 <0.001 <.001 .020 -- .010 .002 .099 -- --

 Jewelry, precious metals [39] 36 -- <.001 .063 -- <.001 -- .004 <.001 .012

Total Industrial [20-39] <0.001 0.168 0.681 0.003 0.030 0.023 0.154 <0.001 0.098

Commercial [40-97]

Transportation, communication, utilities 

[40-49]

51 0.001 -- -- -- <0.001 0.006 -- -- 0.007

Wholesale trade [50-51] 58 <.001 -- 0.001 -- -- .002 -- -- --

Retail trade [52-59] 58 .009 0.013 .025 -- .077 .059 -- 0.003 .006

Finance, insurance, real 

estate [60-67]

71 -- -- -- -- .027 .026 -- -- --

Services [70-89] 106 .002 .107 .035 <0.001 .414 .368 0.056 .006 .012

Public administration 

[91-97]

71 -- -- .011 -- -- .218 -- -- --

Total Commercial 

[40-97] 

 0.012 0.120 0.072 <0.001 0.518 0.679 0.056 0.009 0.025
Water Use 33

Return Flow and Wastewater Interbasin 

Transfers

In Rhode Island, commercial and industrial dischargers 

are required to report to the Rhode Island Department of 

Environmental Management (RIDEM) Office of Water 

Resources the rates of water returned to the environment. 

These dischargers, referred to as Rhode Island Pollutant 

Discharge Elimination Systems (RIPDES), return wastewater 

to surface water (usually to rivers) or, in some cases, to the 

ground-water system. In addition, local and regional facilities 

that treat wastewater are required to report wastewater 

discharges into rivers in Rhode Island. When reported data 

from dischargers were not available, the return flow was 

estimated. Data were estimated for domestic, commercial, 

and industrial users on septic systems which were assumed to 

return water to the ground. The total surface-water return flow 

in the East Narragansett Bay study area was 0.003 Mgal/d, and 

the total estimated ground-water return flow was 2.587 Mgal/d 

(table 14). Wastewater interbasin transfers are wastewater 

conveyed across hydrologic divides and boundaries between 

defined study areas. The wastewater is an import, or a gain to 

an area if it is collected from another area. Wastewater is an 

export, or a loss to an area, if the wastewater in that area is 

collected, processed, and returned to the environment outside 

of that area.

Site-Specific Return Flow

In Rhode Island, commercial and industrial discharges 

that release water to the environment are identified as sitespecific RIPDES sites, and some are required to report their 

discharges to the RIDEM. Return-flow data were collected 

from the RIDEM for these small discharges in the East 

Narragansett Bay study area (table 15). Discharge pipes 

dispose of water used during industrial and commercial 

processes. The water includes condensation from airconditioning systems; thus, in systems that include air 

conditioning, it is possible for return flow to exceed intake. 

The total of the RIPDES discharges in the East Narragansett 

Bay study area to the rivers was 0.003 Mgal/d from one site 

in Tiverton in the Southeastern Narragansett region (table 15). 

Several other RIPDES sites in towns in the study area 

discharged about 1.544 Mgal/d to the bay (table 15).

Table 14. Estimated public- and self-disposed domestic, commercial, and industrial, and total self-disposed wastewater by region in 

the East Narragansett Bay study area, eastern Rhode Island, 1995–99.

[Public disposal, wastewater collection to treatment plant; self-disposal, inflow to ground; RIPDES, Rhode Island Pollution Discharge Elimination System. 

Mgal/d, million gallons per day; --, not applicable; <0.001, value not included in totals]

City/Town

Estimated 

domestic disposal

 (Mgal/d)

Estimated 

commercial disposal 

(Mgal/d)

Estimated

industrial disposal 

(Mgal/d)

Total 

self-disposal to 

study area

(Mgal/d) Public Self Public Self Public Self

Northeastern Narragansett Region

Barrington 0.890 0.007 0.216 -- 0.005 -- 0.007

Bristol 1.109 .152 .329 -- .054 -- .152

East Providence 2.668 .080 1.025 -- .151 -- .080

Warren .571 .081 .289 .001 .037 .002 .084

Region total 5.237 .320 1.859 .001 .248 .002 .323

Southeastern Narragansett Region

Little Compton .003 .199 -- <.001 -- -- .199

Tiverton .050 .804 .006 .002 .001 -- .809

Region total .053 1.002 .006 .002 .001 1.008

East Narragansett Islands Region

Middletown .942 .146 .895 .012 -- .028 .186

Newport 1.371 .028 1.593 .042 -- .021 .091

Portsmouth .155 .844 .050 <.001 -- .139 .983

Region total 2.468 1.019 2.538 .054 -- .187 1.260

Study-area total 7.759 2.341 4.403 0.057 0.249 0.189 2.591
34 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Return Flow from Wastewater-Treatment 

Facilities 

Monthly data were collected for public-disposal 

wastewater-treatment facilities (WWTFS) in or serving the 

towns in the East Narragansett Bay study area (table 16). 

The WWTFS serving populations in and outside of the East 

Narragansett Bay study area include the Bristol WastewaterTreatment Facility, the East Providence Wastewater-Treatment 

Facility, Narragansett Bay Commission’s facility at Bucklin 

Point (in East Providence), the Newport Wastewater-Treatment 

Facility, and the Warren Wastewater-Treatment Facility. 

All of the wastewater-treatment facilities were in the study 

area, and discharged the wastewater outside of the basin into 

Narragansett Bay. For Bristol, wastewater was collected in the 

study area and processed at the Bristol Wastewater-Treatment 

Facility. About 3.153 Mgal/d of wastewater, however, was 

discharged from the study area to Narragansett Bay during 

the study period. For Barrington and parts of East Providence, 

wastewater collection was in the study area and processed at 

the East Providence Wastewater-Treatment Facility. About 

6.640 Mgal/d of wastewater, however, was discharged from 

the study area to Narragansett Bay from 1995 through 1999. 

The Narragansett Bay Commission’s facility at Bucklin 

Point (in East Providence) is in the study area and received 

wastewater from East Providence in the study area as well as 

from communities outside of the study area. The Bucklin Point 

facility discharged about 23.92 Mgal/d of wastewater from 

the study area to Narragansett Bay during the study period. 

The Newport and Warren Wastewater-Treatment Facilities are 

in the study area, collected wastewater in the study area, and 

discharged about 8.126 and 1.826 Mgal/d, respectively, from 

the study area to Narragansett Bay from 1995 through 1999. 

Table 15. Return flows by region for the Rhode Island Pollutant Discharge Elimination System sites in the East Narragansett Bay 

study area, eastern Rhode Island, 1995–99.

[Reference no. identifies the site on figure 4. The return flow to the study area is assumed to discharge to freshwater, whereas the discharge to Narragansett 

Bay is to saltwater and exported out of the study area. Mgal/d, Million gallons per day; --, not applicable]

Return-flow site Reference no.

City/town 

(Locality)

Discharge-permit

number Receiving-water body

Return flow to 

Narragansett 

Bay

Northeastern Narragansett Region

Chevron Terminal 1 East Providence RI0001325 Providence River 0.259

Mobil Pipe Line Co. 2 East Providence 

(Riverside)

RI0001333 Providence River 1.136

Region total 1.395

Southeastern Narragansett Region

Inland Fuel Terminals, Inc. 3 Tiverton RI0000442 Mount Hope Bay 0.024

Tiverton High School 4 Tiverton RI0100200 Sin and Flesh Brook --1

Region total 0.027

East Narragansett Islands Region

Defense Fuel Depot – U.S. Naval Station 5 Newport RI0020150 Narragansett Bay 0.122

International Manufacturing Services 6 Portsmouth RI0021334 Sakonnet River .001

Mother of Hope Novitiate 

(Freedom Bay Development)

7 Portsmouth RI0020346 Narragansett Bay .001

Portsmouth Middle School 8 Portsmouth RI0100242 Narragansett Bay <.001

Raytheon Corporation 9 Portsmouth RI0000281 Weaver Cove .001

Region total 0.125

Study area total 1.544

1 One RIPDES site in Tiverton discharged 0.003 Mgal/d to a river in the study area.
Water Use 35

Septic-System Return Flow

Return flow from septic systems was estimated for 

domestic, industrial, and commercial water use. Populations 

on public wastewater collection were used to determine the 

populations on septic systems (self-disposed water; table 

1). An estimated 85 percent of the water used by domestic 

populations on septic systems was returned to ground water, 

and therefore 15 percent of the water used was consumed 

(Solley and others, 1998). To calculate the amount of 

domestic self-disposed water, the population was multiplied 

by the water-use coefficient for self-supply water use 

(71 gal/d/person), converted to Mgal/d, and multiplied by 0.85. 

The results for domestic self-disposed water are summarized 

by town and region in table 14 and illustrated by region in 

figure 8. An estimated 90 percent of industrial and commercial 

return flow is disposed to ground water, and the remaining 

10 percent is consumptive water use (Horn, 2000). A summary 

of the consumptive water use for domestic, commercial, 

industrial, and agricultural water users by region is in table 12, 

and a summary of the return flow is in table 14.

Interbasin Transfers of Wastewater

Wastewater collected by the Narragansett Bay 

Commission’s facility at Bucklin Point from East Providence 

(1.685 Mgal/d) and wastewater from outside the Northeast 

Narragansett region (22.235 Mgal/d) is discharged directly to 

the bay. Some East Providence wastewater (5.529 Mgal/d) is 

collected by the East Providence WWTF, which also collects 

wastewater from the town of Barrington (1.11 Mgal/d) and 

discharges all of the water directly to the bay. Two other minor 

WWTFs (Warren and Bristol) in the region collect wastewater 

from the towns of Warren (1.826 Mgal/d) and Bristol (3.153 

Mgal/d). This wastewater is discharged directly into the bay. 

Finally, a total of 8.126 Mgal/d of wastewater—collected from 

municipalities on Aquidneck Island in the East Narragansett 

Islands region—is also discharged directly to the bay. A total 

of about 43.66 Mgal/d of wastewater is disposed into the bay, 

of which 13.30 Mgal/d is collected from the Northeastern 

Narragansett region; the Southeastern Narragansett region 

does not collect or discharge wastewater. 

Table 16. Return flows to Narragansett Bay from wastewater-treatment facilities that are in the study area and serve towns in and 

outside of the East Narragansett Bay study area, eastern Rhode Island, 1995–99.

[Reference letter identifies the site on figure 4. Mgal/d, million gallons per day]

Wastewater-treatment facility Reference 

letter

Dischargepermit 

number

Cities/towns served in 

study area

Cities/towns served 

outside of the study area

Average 

discharge rate 

1995–99

(Mgal/d)

Narragansett Bay Commission 

- Bucklin Point WastewaterTreatment Facility1

A RI0100315 East Providence Central Falls, 

Cumberland, Lincoln, 

Pawtucket, Smithfield

23.92

East Providence WastewaterTreatment Facility2B RI0100048 East Providence, Barrington -- 6.640

Warren Wastewater-Treatment 

Facility3

C RI0100056 Warren -- 1.826

Bristol Wastewater-Treatment 

Facility

D RI0100005 Bristol -- 3.153

Newport Wastewater-Treatment 

Facility4

E RI0100293 Middletown, Newport, U.S. 

Naval Station

 -- 8.126

1 Return flow to Providence River.

2 Return flow to Seekonk River.

3 Return flow to Warren River.

4 Return flow to Newport Harbor.
36 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Water-Use Summary

Within the computed balance of the water withdrawals, 

use by category, nonaccount water, consumptive, and return 

flows, there is a percentage error that is attributed to the 

summation of metered (or reported) and estimated water-use 

components for each category. Public water-supply withdrawals were metered (or reported), for example, and water use 

by region was estimated, and the return flow was metered 

(or reported) and estimated. Similarly, RIPDES data were 

metered (or reported) and the withdrawal and uses were estimated. 

The water withdrawals in the East Narragansett Bay 

study area were 9.555 Mgal/d. A net amount of 8.750 Mgal/d 

of potable water was imported from other study areas:

•	 8.413 Mgal/d was imported to the Northeastern 

Narragansett region;

•	 0.236 Mgal/d of water withdrawn from the 

Southeastern Narragansett region was exported, 

and 0.337 Mgal/d of water was purchased by 

water suppliers in the Southeastern Narragansett region from suppliers outside the region 

(not including nonaccount water); and

•	 0.573 Mgal/d was imported to the East 

Narragansett Islands region from the 

Southeastern Narragansett region.

The estimated total consumptive water use was 2.449 Mgal/d 

in the East Narragansett Bay study area and is considered a 

loss. The results are summarized in table 17. 

The wastewater imports to and exports from the East 

Narragansett Bay study area were calculated from the total categorical water use (domestic, commercial, industrial, and agricultural) minus the consumptive use and minus the total return 

flow. The result is the wastewater imported to (+) or exported 

from (-) the study area. For the East Narragansett Bay study 

area, the total wastewater returned to Narragansett Bay (not 

including water from combined sewer overflow; CSO) was 

11.439 Mgal/d; this total represents all public-disposal wastewater in the study area. As much as 42 percent of wastewater 

discharged from Bucklin Point may be composed of CSO. For 

the entire study area, the total of the imports and exports was a 

net loss of 2.692 Mgal/d. The totals for the regions were a net 

gain of 1.478 Mgal/d for the Northeastern Narragansett region; 

a net loss of 0.268 Mgal/d for the Southeastern Narragansett 

region; and a net loss of 3.902 Mgal/d for the East Narragansett Islands region. The results are summarized in table 17. 

Table 17. Summary of estimated water withdrawals, imports, exports, use, nonaccount water use, consumptive use, and return flow 

in the East Narragansett Bay study area, eastern Rhode Island, 1995–99. 

[Nonaccount water is a loss of water through the system. Consumptive use is an export. Net import and exports are the sum of the potable water and wastewater 

imports and exports and do not include nonaccount and consumptive water uses. All values are in Mgal/d, million gallons per day; <0.001, values not included 

in town and study-area totals; DOM, domestic; COM, commercial; IND, industrial; AG, agricultural; +, potable distribution and wastewater collection imported 

to the study area; -, potable distribution and wastewater collection exported from the study area; --, not applicable]

Region

Total 

water 

withdrawals,

public and 

self

Potable 

water 

imports 

(+) and 

exports (-) 

Total water use, public 

and self 

Consumptive use 

Return flow Wastewater 

imports 

(+) and 

exports (-) 

Net 

imports 

(+) and 

exports (-) 

Use 

(DOM, 

COM, IND, 

AG) 

Nonaccount 

(public 

use)

Surface 

water

Ground 

water

Northeastern 

Narragansett Region

1.082 +8.413 8.482 1.013 1.224 -- 0.323 -6.935 +1.478

Southeastern 

Narragansett Region

1.692 -.236 1.289 .167 .249 0.003 1.005 -.032 -.268

East Narragansett 

Islands Region

6.781 +.573 6.711 .643 .976 -- 1.260 -4.475 -3.902

Study-area total 9.555 +8.750 16.482 1.823 2.449 0.003 2.588 -11.442 -2.692
Water Availability 37

Water Availability

During periods of little or no precipitation, streamflow 

is sustained primarily by inflow from surface-water storage 

(lakes and reservoirs) and from ground-water discharge; direct 

runoff is assumed to be negligible. Water withdrawals are 

commonly higher during the summer, and precipitation and 

ground-water discharge may be lower in the summer than the 

annual average. Therefore, it was important to estimate the 

amount of available water and to compare it to the withdrawals 

in the study area. Water-availability estimates that are made 

from stream base-flow calculations are conservative because 

actual streamflows generally are greater than base flow except 

during periods of no recharge from precipitation. 

Summer Ground-Water Availability at Selected 

Index Stations

During times of little or no recharge in the form of 

precipitation, flows in the surface- and ground-water system 

originate from storage predominantly in the stratified sand 

and gravel deposits; water flows through the till deposits as 

well, but at a slower rate. The ground water discharging to 

streams during times of little or no recharge from precipitation 

is referred to as base flow. Ground-water availability during 

times of little or no precipitation can be estimated on the basis 

of streamflow data collected for selected index stream-gaging 

stations and the computer program PART. Index stations were 

chosen whose upstream areal percentages of sand and gravel 

deposits and till deposits are similar to those in the study area. 

For the East Narragansett Bay study area, two stream-gaging 

stations were selected for this analysis—the Adamsville Brook 

at Adamsville (station 01106000) and the Pawcatuck River 

at Wood River Junction (station 01117500). The data for Ten 

Mile River at Pawtucket Avenue at East Providence (station 

01109403) were analyzed and are presented for comparison 

to the data for the Pawcatuck station; however, the data for the 

Ten Mile station were not used in this assessment of groundwater availability because of the regulation (multiple wastewater discharges and diversions from reservoirs) upstream of 

the station. These regulations alter flow during periods of little 

or no recharge (Rutledge, 1993, 1998). Drainage areas, mean 

flow, minimum flow statistics, and other data are presented for 

all three stations in table 18. 

The PART program, a hydrograph-separation application 

(Rutledge, 1993, 1998), was applied to the data collected for 

the two selected index stations to determine the 75th, 50th, 

and 25th percentiles of the total base flow (the basic scenario), 

the 75th, 50th, and 25th percentiles of the base flow minus 

the 7-day, 10-year low-flow (the 7Q10 scenario), and the 

75th, 50th, and 25th percentiles of the base flow minus the 

Aquatic Base Flow (the ABF scenario) for the summer months 

(table 19). (See Glossary at the back of the report for definitions of terms.) For each scenario, flows were apportioned 

according to the contributions of base flow from stratified 

sand and gravel and from till deposits upstream of the two 

index stations. The drainage areas of the index stations were 

multiplied by the areal percentages of the sand and gravel 

and till (surficial) deposits to obtain the areas of the surficial 

deposits upstream of the stations. Values of base-flow contributions from the two types of surficial deposits for the Pawcatuck index station were based on previous work by the U.S. 

Geological Survey (Dickerman and others, 1997). The areas 

of sand and gravel deposits and till deposits for each index station were divided into the estimated base flow from each type 

of deposit. The resulting values are base flows per unit area in 

million gallons per day per square mile (Mgal/d/mi2) for the 

two types of deposits upstream of each index station. Finally, 

these base flows per unit area for each type of deposit, each 

index station, and each scenario were multiplied by the area 

of the same type of deposit in the region(s) assigned to that 

index station to give the gross yield, gross yield for 7Q10, and 

gross yield for ABF scenarios; the base flow calculated for the 

three regions is referred to as the gross yield. In regions with 

surface-water reservoirs, the gross yields were added to any 

previously published safe yields from reservoirs to give the 

total amount of water available in each region. It is important 

to note that because data from the Ten Mile station yielded 

higher per-square-mile base-flow values than data from the 

Pawcatuck station for both types of deposits, the values for the 

Ten Mile station were assumed to be affected by regulation 

upstream of the station and thus were not used.
38 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Table 18. U.S. Geological Survey stream-gaging stations and minimum streamflows used in the analysis of water availability in the 

East Narragansett Bay study area, eastern Rhode Island.

[Water years are from October to September and may differ from the period of record in the data report. 7Q10, 7-day, 10-year low flow; ABF, Aquatic base 

flow, based on the median of the monthly means; Mgal/d, million gallons per day; USGS, U.S. Geological Survey; --, data from this station were not applied to 

any region.]

USGS streamgaging-station 

number

Station name Region to which flow 

data were applied

Drainage 

area

(mi2)

Percentage of 

sand and 

gravel 

Mean flow 

(Mgal/d)

[calendar 

years] 

Minimum flows (Mgal/d)

7Q10

[water years]

ABF

[calendar 

years]

01106000 Adamsville Brook at 

Adamsville, RI

Southeastern Narragansett and East 

Narragansett Islands

 8.01 0.7 9.229

[1941–1977]

0.349

 [1941–1978]

 0.779

 [1941–1978]

01109403 Ten Mile River at Pawtucket Avenue at East 

Providence, RI1

-- 53.1 58 66.13

[1987–2002]

8.305

 [1987–2002]

 25.73

 [1987–2002]

01117500 Pawcatuck River at 

Wood River Junction, 

RI

Northeastern Narragansett100 47 126.7

[1941–2000]

17.07

 [1942–2002]

45.45

 [1941–2000]

1Because regulation and diversions upstream of the station affected estimated base flows, the data for this station were not used for estimating water 

availability during the summer months.

Table 19. Summer water availability from base flows for the selected index stream-gaging stations used in the water-availability 

analysis for the East Narragansett Bay study area, Rhode Island

[All values are in Mgal/d, million gallons per day; 75, 50, and 25 are percentiles. 7Q10, 7-day, 10-year low flow; ABF, Aquatic base flow, based on the median 

of the August monthly means; --, values less than zero and not used]

Month 

Estimated base flow 

(Mgal/d)

Estimated base flow minus 7Q10 

(Mgal/d)

Estimated base flow minus 

ABF (Mgal/d)

75 50 25 75 50 25 75 50 25

Adamsville River at Adamsville, RI stream-gaging station1

June 4.921 3.528 2.414 4.572 3.179 2.065 4.142 2.749 1.635

July 1.797 .899 .450 1.448 .549 .100 1.018 .119 --

August 1.662 .584 .180 1.313 .235 -- .883 -- --

September 1.346 .325 .093 .997 -- -- .567 -- --

Ten Mile River at Pawtucket Ave., East Providence, RI stream-gaging station2

June 80.93 53.24 44.31 72.63 44.93 36.01 55.20 27.50 18.58

July 48.24 31.57 23.53 39.94 23.26 15.22 22.51 5.833 --

August 26.80 19.66 14.15 18.50 11.35 11.39 1.068 -- --

September 26.77 19.69 14.92 18.47 11.39 6.619 1.038 -- --

Pawcatuck River at Wood River Junction, RI stream-gaging station3

June 115.5 90.40 72.00 98.40 73.33 54.93 70.02 44.95 26.55

July 66.45 51.32 41.36 49.39 34.25 24.29 21.00 5.862 --

August 61.27 42.06 30.29 44.20 24.99 13.22 15.82 -- --

September 48.53 34.48 24.34 31.46 17.41 7.268 3.081 -- --

1 Base-flow estimates for the station are from the years 1941 through 1977. The drainage area upstream of the station is 8.01 mi2. Because the areal 

percentage of sand and gravel is only 0.7 percent, 100 percent of the base flow was assumed to be from till.

2 Base-flow estimates for the station are from the years 1987 through 2002. The drainage area upstream of the station is 53.1 mi2, of which 58 percent is sand 

and gravel. The contribution to base flow from sand and gravel is about 70 percent.

3 Base-flow estimates for the station are from the years 1941 through 2000. The data have been previously published in Wild and Nimiroski (2004). The 

drainage area upstream of the station is 100 mi2, of which 47 percent is sand and gravel. The contribution to base flow from sand and gravel is about 71 percent.
Water Availability 39

The Pawcatuck River at Wood River Junction streamgaging station was used as the index station for the Northeastern Narragansett region. For this station, it was estimated 

that about 71 percent of the base flow was from sand and 

gravel deposits and 29 percent was from till deposits (Dickerman and others, 1997). The Adamsville Brook stream-gaging 

station was used as the index station for the Southeastern and 

East Narragansett Islands regions. Because the percentage of 

sand and gravel deposits upstream of the Adamsville streamgaging station was less than 1 percent, all of the base flow was 

considered to be from till deposits. In addition to determining 

the water availability from ground water, previously published 

safe-yield values determined for surface-water reservoirs were 

added to the ground water available in the regions where there 

are withdrawals from surface-water reservoirs. 

To illustrate long-term water-table fluctuations, 

figures 15-17 present water levels monitored at three USGS till 

wells in Rhode Island within the study area: Little Compton 

(LTW-142), Portsmouth (POW-551), and Tiverton (TIW-274). 

The wells are completed in different areas and show different 

water-table fluctuations for each well. In turn, these fluctuations demonstrate how ground-water availability can vary 

month to month, year to year, and decade to decade. For more 

information, current and historical data available from surfacewater and ground-water stations in Rhode Island can be 

accessed online from the National Water Information System 

database (http://waterdata.usgs.gov/ri/nwis/nwis).

Summer Water Availability in the Regions

The water-availability estimates for all the tested 

scenarios for the study area and regions are presented in 

table 20. The gross yield at the 50th percentile for the 

basic scenario ranged from 19.08 Mgal/d in September to 

80.52 Mgal/d in June. The gross yield for the 50th percentile 

for the 7Q10 scenario ranged from 7.769 Mgal/d in September 

to 68.93 Mgal/d in June. The safe yields from the surfacewater reservoirs provided in an additional 14.10 Mgal/d, 

and this amount was added to the three gross yields for 

June, July, August, and September to give the total available 

water. The total available water for the basic scenario at the 

50th percentile ranged from 33.18 Mgal/d in September to 

94.62 Mgal/d in June. The total available water for the 7Q10 

Water levels for Little Compton 142 (RILTW-142)

70

75

80

85

90

95

100

DATE WATER LEVEL MEASURED

ALTITUDE OF WATER LEVEL, IN FEET ABOVE NGVD 29

9/1/1992

10/6/1993

11/10/199412/15/1995

1/18/19972/22/19983/29/1999

5/2/20006/6/2001

7/11/2002

8/15/20039/18/2004

Water level

Mean

Median

June and September 1999

June, July, August 2002

Figure 15. Water-level altitudes for Little Compton well 142, 1992–2004. Altitudes as a group are 

accurate within 10 ft. 
40 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Water level

Mean

Median

June, July, August, September 1999

June, July, August, September 2002

Water levels for Tiverton 274 (RITIW-274)

140

142

144

146

148

150

152

154

156

158

160

9/1/1992

1/14/1994

5/29/1995

10/10/1996

2/22/1998

7/7/1999

11/18/2000

4/2/2002

8/15/2003

12/27/2004

ALTITUDE OF WATER LEVEL, IN FEET ABOVE NGVD 29

DATE WATER LEVEL MEASURED

Water levels for Portsmouth 551 (RIPOW-551)

175

180

185

190

195

200

205

210

215

220

225

DATE WATER LEVEL MEASURED

ALTITUDE OF WATER LEVEL, IN FEET ABOVE NGVD 29 

Water level

Mean

Median

June, July, August, September 1999

June, July, August 15, August 28, September 2002

9/1/1992

1/14/1994

5/29/1995

10/10/1996

2/22/1998

7/7/1999

11/18/2000

4/2/2002

8/15/2003

12/27/2004

Figure 16. Water-level altitudes for Portsmouth well 551, 1992–2004. Altitudes of the group are accurate within 1 ft.

Figure 17. Water-level altitudes for Tiverton well 274, 1992–1994. Altitudes of the group are accurate within 5 ft.
Water Availability 41

Table 20. Estimated gross yield, gross yield for the 7-day, 10-year low flow, and gross yield for the Aquatic Base Flow and available water from ground water and surfacewater reservoirs in June, July, August, and September in the East Narragansett Bay study area, Rhode Island.[To calculate the total amount of water available for each scenario and region, add gross yield and safe yield. All values in Mgal/d, million gallons per day; 75, 50, and 25 are percentiles. 7Q10, 7-day, 10-year low flow; ABF, Aquatic Base Flow; --, values at station less than zero and not used]

Region Safe yield

Basic scenario 7Q10 scenario ABF scenario

75 50 25 75 50 25 75 50 25

Estimated gross yield and available water for June

Northeastern Narragansett1 -- 51.52 40.33 32.12 43.90 32.72 24.51 31.24 20.06 11.85Southeastern Narragansett2 31.90 32.46 23.28 15.92 30.17 20.97 13.62 27.32 18.14 10.79

East Narragansett Islands 2 412.20 23.58 16.91 11.57 21.91 15.24 9.898 19.85 13.18 7.837

Total 14.10 107.6 80.52 59.61 95.98 68.93 48.03 78.41 51.38 30.48Total available water 121.70 94.62 73.71 110.10 83.03 62.13 92.51 65.48 44.58

Estimated gross yield and available water for July

Northeastern Narragansett1 -- 29.65 22.90 18.45 22.03 15.28 10.84 9.371 2.615 --

Southeastern Narragansett2 1.90 11.86 5.930 2.965 9.554 3.622 .660 6.717 0.785 --East Narragansett Islands 3 12.20 8.612 4.308 2.154 6.940 2.631 0.479 4.879 0.570 --

Total 14.10 50.12 33.14 23.57 38.52 21.53 11.98 20.97 3.970 --

Total available water 64.22 47.24 37.67 52.62 35.63 26.08 35.07 18.07 14.10

Estimated gross yield and available water for August

Northeastern Narragansett1 -- 27.34 18.76 13.51 19.72 11.15 5.896 7.057 -- --

Southeastern Narragansett2 1.90 10.97 3.852 1.186 8.663 1.551 -- 5.826 -- --East Narragansett Islands 3 12.20 7.968 2.798 0.862 6.293 1.126 -- 4.232 -- --Total 14.10 46.28 25.41 15.56 34.68 13.83 5.896 14.11 -- --Total available water 60.38 39.51 29.66 48.78 27.93 20.00 31.21 14.10 14.10

Estimated gross yield and available water for September

Northeastern Narragansett1 -- 21.65 15.38 10.86 14.04 7.769 3.242 1.375 -- --Southeastern Narragansett2 1.90 8.882 2.146 0.614 6.578 -- -- 3.741 -- --East Narragansett Islands 3 12.20 6.452 1.559 0.446 4.779 -- -- 2.718 -- --Total 14.10 36.98 19.08 11.92 25.40 7.769 3.242 7.834 -- --Total available water 51.08 33.18 26.02 39.50 21.87 17.34 21.93 14.10 14.10

1 Estimated gross yields based on base flow from the Pawcatuck River at Wood River Junction stream-gaging station, from 1941 through 2000.2 Estimated gross yields based on base flow from the Adamsville River stream-gaging station from 1941 through 1980. 3 Safe yield from the Stone Bridge Fire District.4 Safe yield from the Newport Water Works.
42 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

scenario at the 50th percentile ranged from 21.87 Mgal/d in 

September to 83.03 Mgal/d in June (table 20). The most water 

was withdrawn in July and the least in September in the study 

area (table 21). 

To compare the water withdrawals (table 21) to the total 

water available (table 20), the ratios of these two quantities 

were computed for the three scenarios for June, July, 

August, and September for the regions and the entire study 

area (table 22). The closer the ratio of the water withdrawn 

to the estimated water available is to one, the closer the 

withdrawals are to the estimated water available, and the net 

water available is less. The ratios for the basic scenario at the 

50th percentile were highest in August (0.122) and for the 

7Q10 scenario at the 50th percentile in September (0.179). 

The range of the ratios among the regions is shown for July, 

August, and September in figure 18. The ratios for June were 

omitted because they were uniformly low, indicating that the 

amount of available water exceeded the amount withdrawn. 

The cumulative withdrawals from upstream regions have 

not been accounted for in the water-availability ratios for the 

downstream regions. 

Water Budget

Generally, the calculation of a water budget 

includes consideration of all parts of the hydrologic cycle 

(precipitation, evapotranspiration, ground water, and 

streamflow) and the water-use components (withdrawal, 

return flow, interbasin transfer, consumptive use, nonaccount water, and categorical water use). To determine the 

effects that humans have on each region, water budgets were 

calculated by region without considering the amount of water 

imported or exported to and from the region. The water-budget 

components are summarized in table 23.

Precipitation at Kingston, Rhode Island was estimated 

for the period of record for the index stations (table 23). An 

average precipitation of 50.88 in/yr (2.423 Mgal/d/mi2) for the 

period of record 1987–2001 for the Ten Mile River index station was used for the Northeastern Narragansett region; for the 

Southeastern and East Narragansett Islands regions, an average 

precipitation of 45.81 in/yr (2.179 Mgal/d/mi2) for the period 

of record 1941–1977 for the Adamsville station was used. 

MASSACHUSETTS RHODE 

ISLAND

RHODE 

ISLAND

MASSACHUSETTS RHODE 

ISLAND

MASSACHUSETTS

EXPLANATION

Northeastern Southeastern East Narragansett Islands

East Narragansett Bay study regions

A July B August C September

0.114 0.119 0.099

0.373

0.094 0.123 0.130

0.544 0.894

Figure 18. Withdrawal-to-water-availability ratios for (A ) July, (B ) August, and (C ) September for the regions in the East 

Narragansett Bay study area at the 50th percentile for the 7-day, 10-year low-flow scenario.
Water Availability 43

Table 21. Average public- and self-supply withdrawals in June, July, August, and September in the regions of the East Narragansett 

Bay study area, eastern Rhode Island, 1995–99.

[All values are in Mgal/d, million gallons per day]

Regions

Average water withdrawals 1995–99

(Mgal/d)

June July August September

Public Self Public Self Public Self Public Self

Northeastern Narragansett 0.612 0.856 0.636 0.796 0.578 0.791 0.608 0.402

Southeastern Narragansett 1.159 .847 1.186 .875 1.132 .746 1.033 .665

East Narragansett Islands .512 1.074 .590 1.098 .602 .987 .657 .555

Study-area total 2.283 2.777 2.412 2.769 2.312 2.524 2.298 1.622

Table 22. Estimated withdrawal-to-availability ratios for June, July, August, and September in the East Narragansett Bay study area, 

eastern Rhode Island.

[Results were obtained by dividing the total water withdrawals for each month in table 21 by the total available water in table 20. 75, 50, and 25 are 

percentiles. 7Q10, 7-day, 10-year low flow; ABF, Aquatic Base Flow; --, values at station less than zero and not used]

Region

Basic scenario 7Q10 scenario ABF scenario

75 50 25 75 50 25 75 50 25

June

Northeastern region1 0.028 0.036 0.046 0.033 0.045 0.060 0.047 0.073 0.124

Southeastern region2 .057 .080 .113 .063 .088 .129 .069 .100 .158

East Narragansett 

Islands region2

 .044 .054 .067 .046 .058 .072 .049 .062 .079

Study-area total 0.042 0.053 0.069 0.046 0.061 0.081 0.055 0.077 0.114

July

Northeastern region1 0.048 0.063 0.078 0.065 0.094 0.132 0.153 0.548 --

Southeastern region2 .150 .263 .424 .180 .373 .805 .239 .768 1.085

East Narragansett 

Islands region2

.081 .102 .118 .088 .114 .133 .099 .132 .138

Study-area total 0.081 0.110 0.138 0.098 0.145 0.199 0.148 0.287 0.367

August

Northeastern region1 0.050 0.073 0.101 0.069 0.123 0.232 0.194 -- --

Southeastern region2 .146 .326 .609 .178 .544 .988 .243 .988 .988

East Narragansett 

Islands region2

.079 .106 .122 .086 .119 .130 .097 .130 .130

Study-area total 0.080 0.122 0.163 0.099 0.173 0.242 0.155 0.343 0.343

September

Northeastern region1 0.047 0.066 0.093 0.072 0.130 0.312 0.735 -- --

Southeastern region2 .158 .420 .675 .200 .894 .894 .301 .894 .894

East Narragansett 

Islands region2

.065 .088 .096 .071 .099 .099 .081 .099 .099

Study-area total 0.077 0.118 0.151 0.099 0.179 0.226 0.179 0.278 0.278

1Available water based on base flow from the Pawcatuck River at Wood River Junction stream-gaging station for the period 1941 through 2000. 

2Available water based on the sum of the base flow from the Adamsville River at Adamsville stream-gaging station for the period 1941 through 1980 and the 

safe yield from the surface-water reservoirs.
44 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

Table 23. Average long-term water budget by region for the East Narragansett Bay study area, eastern Rhode Island. 

[All values in Mgal/d, million gallons per day; RIPDES, Rhode Island Pollution Discharge Elimination System; Mgal/d/mi2, million gallons per day per square 

mile; mi2, square miles; in/yr, inches per year]

Water-budget component

Rate of flow

Northeastern 

Narragansett

 region

Southeastern

Narragansett

 region

East Narragansett 

Islands

 region

East Narragansett Bay 

study-area

total

Estimated inflow 

Precipitation 191.69 2113.4 284.45 289.5

Return flow3 .323 1.008 1.260 2.591

Total inflow 92.01 114.4 85.71 292.1

Estimated outflow

Evapotranspiration4 543.48 653.04 641.83 138.4

Outflow7 47.45 59.67 37.10 144.1

Water withdrawals8 1.082 1.692 6.781 9.555

Total outflow 92.01 114.4 85.71 292.1

Streamflow per square mile 1.254 1.146 .904 1.101

Total drainage area at outlet9 37.84 52.05 41.05 130.9

1 Based on average precipitation per unit area (50.88 in/yr, equivalent to 2.423 Mgal/d/mi2) at Kingston, RI, for the period 1987–2001 (data from the National 

Oceanic and Atmospheric Administration, 2002a).

2 Based on average precipitation per unit area (45.81 in/yr, equivalent to 2.179 Mgal/d/mi2) at Kingston, RI, for the period 1941–1977 (data from the National 

Oceanic and Atmospheric Administration, 2002a).

3 Based on the total return flow from septic, RIPDES, and wastewater-treatment facilities in the East Narragansett Bay study area, 1995–99. 

4 Evapotranspiration based on the difference between the average precipitation and average monthly flow at the index stream-gaging station assigned to the 

region.

5 Based on the difference between the average annual precipitation per unit area (2.423 Mgal/d/mi2; data from the National Oceanic and Atmospheric Administration, 2002a) and average annual flow per unit area (1.274 Mgal/d/mi2) at the stream-gaging station Ten Mile River at Pawtucket Ave. at East Providence for 

the period 1987–2001.

6 Based on the difference between the average annual precipitation per unit area (2.179 Mgal/d/mi2; data from the National Oceanic and Atmospheric 

Administration, 2002a) and average annual flow per unit area (1.160 Mgal/d/mi2) at the stream-gaging station Adamsville Brook at Adamsville for the period 

1941–1977. 

7 Based on the sum of the inflows minus the sum of the withdrawals minus evapotranspiration.

8 Water-withdrawal types include domestic, commercial, industrial, and agricultural from public and self-supply.

9 Based on the sum of the regional drainage area and drainage areas upstream of the region. 
Summary 45

Return flow includes the average rate of disposal from septic 

systems and RIPDES sites from 1995 through 1999. Evapotranspiration was estimated as the difference between the precipitation per unit area and the mean annual flow per unit area 

at each of the index stations. The outflow from each region 

was estimated as the sum of the inflows minus the withdrawals 

minus evapotranspiration. 

The total water budget for the Northeastern Narragansett 

region was 92.01 Mgal/d. The estimated inflows from 

precipitation and return flow were 99 and less than 1 percent 

of the total water budget, and the estimated evapotranspiration, 

outflow, and water withdrawals were 47, 52, and 1 percent, 

respectively. The total water budget for the Southeastern 

Narragansett region was 114.4 Mgal/d. The estimated 

inflows from precipitation and return flow were 99 and less 

than 1 percent of the total water budget, and the estimated 

evapotranspiration, outflow, and water withdrawals were 46, 

52, and 1 percent, respectively. The total water budget for the 

East Islands region was 85.71 Mgal/d. The estimated inflows 

from precipitation and return flow were 99 and 1 percent 

of the total water budget, and the estimated outflows from 

evapotranspiration, streamflow, and water withdrawals were 

49, 43, and 8 percent, respectively. Ground-water underflow 

was considered to be negligible in all regions. 

Summary

During a drought in 1999, ground-water levels and 

streamflows dropped below long-term averages throughout 

Rhode Island. Consequently, the State of Rhode Island became 

concerned about water availability, and an investigation was 

needed to assess water use and availability throughout the 

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

with the Rhode Island Water Resources Board (RIWRB), 

completed a series of nine water use and availability 

investigations to describe the relations between the water-use 

and hydrologic-cycle components for surface and ground 

water during periods of little or no recharge. The investigation 

for the East Narragansett Bay study area (130.9 mi2) in eastern 

Rhode Island is described here.

Water use and availability in the three regions of the East 

Narragansett Bay study area were estimated for periods of 

little or no recharge during the period 1995–99. Water-use data 

were collected by public-supply and wastewater-collection 

systems in the study area. Self-supply and other unavailable 

data were estimated by using previously published methods 

and additional methods developed in this study. Water 

availability for the three regions was calculated by a method 

of determining ground-water discharge during streamflowrecession periods in the summer (June–September). A 

basin water budget was also calculated to summarize the 

components of the hydrologic cycle on the basis of the longterm period of record and selected water-use components for 

the study period.

The three major water suppliers in the study area 

withdrew an average of 7.601 Mgal/d from ground water 

and surface water during the study period. The estimated 

water withdrawals from minor suppliers during the study 

period were 0.063 Mgal/d. Public- and self-supply domestic, 

commercial, industrial, and agricultural withdrawals in the 

study area were from ground water and surface water. Selfsupply domestic, industrial, commercial, and agricultural 

withdrawals from the study area totaled 1.891 Mgal/d. Water 

use in the study area averaged 16.48 Mgal/d for 1995–99. The 

average return flow in the study area was 2.591 Mgal/d, which 

included effluent from one permitted facility and self-disposed 

wastewater from septic systems.

Ground-water availability was estimated from output 

from a computer-based hydrograph-separation application. 

Data were collected at selected index stream-gaging stations 

for the 75th, 50th, and 25th percentiles of the total base flow, 

the base flow minus the 7-day, 10-year low-flow (7Q10), 

and the base flow minus the Aquatic Base Flow (ABF). The 

index stations used were the Adamsville Brook at Adamsville 

(01106000) and the Pawcatuck River at Wood River Junction 

station (01117500). Data from the Adamsville station were 

used to compute water availability in the Southeastern 

Narragansett and East Islands regions. Data from the 

Pawcatuck station were used to compute water availability in 

the Northeastern Narragansett region. 

Because water withdrawals and use are greater during 

the summer than other times in the year, water availability at 

the 75th, 50th, and 25th percentiles for June, July, August, 

and September was assessed and compared to the water 

withdrawals in the study area and regions. The average 

water withdrawals for the East Narragansett Bay study area 

ranged from 3.920 Mgal/d in September to 5.181 Mgal/d 

in July for the study period. The total water available from 

ground water and surface water ranged from 51.08 Mgal/d in 

September to 121.7 Mgal/d in June for the 75th percentile; 

from 33.18 Mgal/d in September to 94.62 Mgal/d in June 

for the 50th percentile; and from 26.02 Mgal/d in September 

to 73.71 Mgal/d in June for the 25th percentile. The water 

availability from ground water in the study area for the 50th 

percentile for the basic scenario ranged from 19.08 Mgal/d in 

September to 80.52 Mgal/d in June, and for the 7Q10 scenario 

ranged from 7.769 Mgal/d in September to 68.93 Mgal/d in 

June. The total safe yield for the surface-water reservoirs in 

the study area was 14.1 Mgal/d.

The ratios of water withdrawn to water available were 

calculated for June, July, August, and September as an 

indicator of net water availability within the three individual 

regions and in the study area as a whole. The closer the 

withdrawals are to the estimated water available, the closer 

the ratio is to one. The ratios were calculated for three flow 

scenarios for the 75th, 50th, and 25th percentiles for each 

region. Withdrawals were higher in July than in the other 

summer months.
46 Estimated Water Use and Availability in the East Narragansett Bay Study Area, Rhode Island, 1995–99

A long-term water budget was calculated for the East 

Narragansett Bay study area to identify and assess the study 

area and region inflow and outflows. The water withdrawals 

and return flows used in the budget were from the period 

of study (1995–99). For the water budget, it was assumed 

that inflow equals outflow. The total water budget for the 

study area was 292.1 Mgal/d. The estimated inflows from 

precipitation and return flow were 99 and less than 1 percent 

of the budget, respectively. The estimated outflows from 

evapotranspiration, streamflow, and water withdrawals were 

47, 49, and 3 percent of the budget, respectively.

Acknowledgments

Original water-use withdrawal and discharge data were 

collected from the public water-supply districts; the Office 

of Water Resources of the Rhode Island Department of 

Environmental Management (RIDEM); individual wastewaterdischarge facilities; and the RIWRB. The author thanks the 

following individuals for assisting in the data-collection 

process: Aaron Mello, RIDEM Office of Water Resources; 

Clay Commons, Rhode Island Department of Health, 

Office of Drinking Water Quality; and Tomas Smieszek, 

U.S. Geological Survey. 

Selected References

Allen, W.B., and Blackhall, J.A., 1950, Ground-water 

resources in Bristol, Warren, and Barrington, Rhode Island: 

Rhode Island Port and Industrial Development Commission 

Scientific Contribution 3, 14 p.

Allen, W.B., and Gorman, L.A., 1959, East Providence 

quadrangle, Massachusetts-Rhode Island: Rhode Island 

Water Resources Board Ground-Water Map 4, 1 pl., scale 

1:24,000.

Allen, W.B., and Kinnison, H.B., 1953, The ground-water 

resources of Rhode Island—a reconnaissance and a section 

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Glossary

7-day, 10-year low flow (7Q10): The discharge at the 10-year 

recurrence interval taken from a frequency curve of annual 

values of the lowest mean discharge for 7 consecutive days 

(the 7-day low flow). 

A

Aquatic Base Flow (ABF): As established by the U.S. Fish 

and Wildlife Service, median flow during the month of August 

considered adequate to protect indigenous aquatic fauna 

throughout the year. It can be calculated as long as there are 

USGS stream-gaging data for at least 25 years of unregulated 

flow, and the drainage area at the stream-gaging station is at 

least 50 square miles (U.S. Fish and Wildlife, 1981).

B

Base flow: Streamflow from ground-water discharge.

C

Commercial water use: Water use for transportation; 

wholesale trade; retail trade; finance, insurance, and real 

estate; services; and public administration (the two-digit 

Standard Industrial Classification codes are in the range 

40-97). The water can be from public or self-supply. 

Consumptive use: Water that is removed from the 

environment through evaporation, transpiration, production, or 

consumed by humans or livestock.

Conveyance: Movement of water from one point to another, 

for example, water withdrawals, water distributions, and 

wastewater collection.

D

Distribution: The conveyance of water from a point of 

withdrawal or purification system to a user or other water 

customer.

Domestic water use: Water use for household purposes, 

such as drinking, food preparation, bathing, washing, clothes 

and dishes, flushing toilets, and watering lawns and gardens. 

Households include single and multifamily dwellings. Also 

called residential water use. The water may be obtained from a 

public water supply or may be self-supplied.

I

Industrial water use: Water use for food, tobacco, textile 

mill products, apparel, lumber and wood; furniture; paper; 

printing; chemicals; petroleum; rubber; leather; stone, 

clay, glass, and concrete; primary metal; fabricated metal; 

machinery; electrical equipment; transportation equipment; 

instruments; and jewelry, precious metals; for which the twodigit Standard Industrial Classification code range is 20-39. 

The water may be obtained from a public water supply or may 

be self-supplied. 

Interbasin transfer: Conveyance of water across a drainage 

or river-basin divide.

Interconnection: Link between public-supply districts 

to convey water. These connections can be for wholesale 

distributions or water-supply backups. 

Irrigation water use: The application of water to lands to 

assist in the growth of crops or pasture, including plants in 

greenhouses. Irrigation water use may also include application 

of water to maintain vegetative growth on recreational lands 

such as parks and golf courses and to provide frost and freeze 

protection of crops.

M

Major water supplier: A public or private water supplier 

that withdraws and distributes water to customers or other 

suppliers for use.

Major user: In Rhode Island, a customer that uses more than 

three million gallons of water per year.

Minor Civil Division (MCD): A term used by the U.S. Census 

Bureau, generally equivalent to a city or town.

Minor public water supplier: A site-specific organization 

or population—for example, a nursing home, condominium 

complex, or mobile-home park—that withdraws its 

own water. 

N

Nonaccount water use: The difference between the metered 

(or reported) supply and the metered (or reported) use for a 

specific period of time, which includes periods during which 

water was used for fire fighting. It comprises authorized and 

unauthorized water uses. 
Glossary 51

O

Outfall: The outlet or structure through which effluent is 

finally discharged into the environment.

P

Per capita water use: The average volume of water used per 

person during a standard time period, generally per day. 

PART: A computer program developed by A.T. Rutledge 

(1993 and 1998) to determine the mean rate of ground-water 

discharge.

Public wastewater system: A system that collects 

wastewater from users or groups of users, conveys the water 

to a wastewater-treatment plant, and then releases the water 

as return flow or sends the water back to users as reclaimed 

wastewater.

Public water use: Water supplied from a public water system 

and used for fire fighting, street washing, and municipal parks 

and swimming pools.

Public-disposed water: Wastewater return flow from public 

and private wastewater-collection systems.

Public-supply water: Water distributed to domestic, 

industrial, commercial, agricultural or other customers by a 

publicly or privately owned water-supply system.

R

Return flow: Water that is returned to surface or ground 

water after use or wastewater treatment, and thus becomes 

available for reuse. Return flow can go directly to surface 

water, directly to ground water through an injection well or 

infiltration bed, or indirectly to ground water through a septic 

system. 

S

Self-disposed water: Water returned to the ground (septic 

systems) by a user or group of users that are not on a 

wastewater-collection system. 

Self-supply water: Water withdrawn from a ground- or 

surface-water source by a user and not obtained from a 

publicly or privately owned water-supply system.

Standard Industrial Classification (SIC) code: Four-digit 

codes established by the U.S. Office of Management and 

Budget and used in the classification of establishments by 

type of activity in which they are engaged. The IWR-MAIN 

coefficients for industrial and commercial water use are based 

on the first two digits.

Surface-water return flow: Effluent that flows from a 

discharge pipe to a river or lake.

W

Wastewater: Water that carries wastes from domestic, 

industrial, and commercial consumers; a mixture of water and 

dissolved or suspended solids.

Wastewater treatment: The processing of wastewater for the 

removal or reduction of contained solids or other undesirable 

constituents.

Wastewater-treatment return flow: Water returned to the 

hydrologic system by wastewater-treatment facilities. Also 

referred to as effluent water.

Water purification: The processes that withdrawn water may 

undergo prior to use. Includes chlorination, fluoridation, and 

filtration.

Water supply: All of the processes that are involved in 

obtaining water for the user before use. Includes withdrawal, 

water treatment, and distribution.

Water use: (1) In a restrictive sense, the term refers to 

water that is actually used for a specific purpose, such as for 

domestic use, irrigation, or industrial processing. (2) More 

broadly, water use pertains to human interaction with and 

impact on the hydrologic cycle, and includes elements such as 

water withdrawal, distribution, consumptive use, wastewater 

collection, and return flow.

Withdrawal: The removal of surface water or ground water 

from the natural hydrologic system for uses such as public 

water supply, industry, commerce, domestic use, irrigation, 

livestock, and thermoelectric power generation.