Estimated Water Use and 

Availability in the Pawcatuck Basin, 

Southern Rhode Island and 

Southeastern Connecticut, 1995–99

By Emily C. Wild and Mark T. Nimiroski

Prepared in cooperation with the

Rhode Island Water Resources Board 

Scientific Investigations Report 2004-5020

U.S. Department of the Interior 

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

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

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Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Wild, E.C., and Nimiroski, M.T., 2004, Estimated water use and availability in the Pawcatuck Basin, southern Rhode 

Island and southeastern Connecticut, 1995–99: U.S. Geological Survey Scientific Investigations Report 2004-5020, 72 p.
 iii

Contents

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

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

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

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

Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

The Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Pawcatuck Subbasins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Minor Civil Divisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Water Use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

New England Water-Use Data System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Public Water Supply and Interbasin Transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

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

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

Self-Supplied Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Commercial and Industrial Water Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Public-Supply Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Self-Supplied Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Agricultural Water Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Return Flow and Interbasin Transfers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Site-Specific Return Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Aggregate Return Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Interbasin Transfers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Water Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Summer Water Availability by Subbasin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Streamflow Depletion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Water Budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

References Cited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
iv 

Figures

1, 2. Diagram showing: 

1. The modified hydrologic cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. The components of water use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3–5. Maps showing:

3. The Pawcatuck Basin and subbasins, southern Rhode Island and 

southeastern Connecticut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4. Aquifers and selected withdrawal wells for the subbasins in the 

Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

5. Stream-gaging stations and wastewater-treatment facilities associated with 

the Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

6–13. Diagrams showing: 

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

industrial, and agricultural withdrawals for the subbasins in the 

Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

7. Public-supply and self-supplied domestic, commercial, industrial, and 

agricultural water use for the subbasins in the Pawcatuck Basin, 1995–99. . . . . . . . . . 25

8. Wastewater-treatment facilities, Rhode Island Pollutant Discharge 

Elimination System, and self-disposed domestic, commercial, and industrial 

water return flow for the subbasins in the Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . 26

9. Kingston Water District withdrawals, distribution, and estimated water 

uses in the Pawcatuck Basin and basin exports, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . 27

10. United Water of Rhode Island withdrawals, treatment, distributions, 

non-account water use in the Pawcatuck Basin and basin exports, 1995–99 . . . . . . . . 28

11. University of Rhode Island withdrawals, water uses, and estimated exported 

return flow in the Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

12. Richmond Water Supply withdrawals, estimated distributions, and estimated 

water uses in the Pawcatuck Basin, 1995–99. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

13. Westerly Water Department withdrawals, distributions, and estimated water 

uses in the Pawcatuck Basin and basin exports, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . 41

14–16. Diagrams showing:

14. Estimated water availability for June, July, August, and September from 

sand and gravel deposits for the subbasins in the Pawcatuck Basin based 

on the A, 50th percentile; B, 50th percentile minus the 7-day, 10-year flow 

criteria; and C, 50th percentile minus the Aquatic Base Flow criteria . . . . . . . . . . . . . . . 51

15. Estimated water availability for June, July, August, and September from 

till deposits for the subbasins in the Pawcatuck Basin based on the 

A, 50th percentile; B, 50th percentile minus the 7-day, 10-year flow criteria; 

and C, 50th percentile minus the Aquatic Base Flow criteria . . . . . . . . . . . . . . . . . . . . . . . 52

16. Estimated water availability for June, July, August, and September for the 

subbasins in the Pawcatuck Basin based on the A, 50th percentile; B, 50th 

percentile minus the 7-day, 10-year flow criteria; and C, 50th percentile 

minus the Aquatic Base Flow criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

17. Map showing the water-withdrawal to water-availability ratio in A, July; B, August; 

and C, September for the subbasins in the Pawcatuck Basin at the 50th percentile 

minus the 7-day, 10-year flow criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56
 v

18, 19. Graphs showing:

18. Decimal percentage of streamflow depletion simulation during 180 days of 

continuous pumping for Kingston Water District wells 1 and 2, Pawcatuck 

Basin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

19 Decimal percentage of streamflow depletion simulation during 180 days of 

continuous pumping for Westerly Water Department wellfields 1 and 2, and 

well 3, Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .63

Tables

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

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

Basin, southern Rhode Island and southeastern Connecticut. . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

2. Summary of climatological data pertinent to the Pawcatuck Basin. . . . . . . . . . . . . . . . . . . . . . . .9

3. Town land area and land-use area by category in the subbasins of the Pawcatuck

Basin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

4. Land-use area and percent land-use area by water-supply district for the subbasins 

in the Pawcatuck Basin study area and areas outside of the Pawcatuck Basin . . . . . . . . . . .12

5. Surface-water and ground-water drainage areas, the percentage of sand and 

gravel deposits and till deposits, and the ground-water reservoirs for the subbasins 

in the Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

6. Defined subbasins in the Pawcatuck Basin study area in Rhode Island compared 

to the 10-digit and 12-digit hydrologic units from the Natural Resources Conservation

Service, Watershed Boundary Dataset in Rhode Island . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

7. Summary of total land area, land area in the Pawcatuck Basin, total 1990 populations,

total estimated 1995–99 populations, estimated 1995-99 populations in the 

Pawcatuck Basin, and land-use area by category in the Pawcatuck Basin . . . . . . . . . . . . . . .17

8. Water suppliers by subbasins in the Pawcatuck Basin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

9. Minor suppliers by subbasins in the Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

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

Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

11. Estimated water use by town and subbasin in the Pawcatuck Basin, 1995–99. . . . . . . . . . . . .30

12. Consumptive water use by town and subbasin in the Pawcatuck Basin, 1995–99. . . . . . . . . .33

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

the Pawcatuck Basin, 1995–99. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

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

metered return flow by subbasin in the Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . . . . . . . . .38

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

System sites in the Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

16. Return flow from wastewater-treatment facilities within and outside of the 

Pawcatuck Basin, 1995–99 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42

17. Summary of estimated water withdrawals, imports, exports, use, non-account 

water use, consumptive use, and return flow in the Pawcatuck Basin, 1995–99 . . . . . . . . . . .43

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

Pawcatuck Basin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44

19. Summer water availability for selected stream-gaging stations in the Pawcatuck 

Basin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
vi 

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

minus the Aquatic Base Flow of water availability for June, July, August, and 

September in the Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

21. Estimated gross yield of water availability for June, July, August, and September in 

the Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

22. Average water withdrawals for June, July, August, and September in the subbasins 

in the Pawcatuck Basin, 1995–99. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

23. Summary of water withdrawals to availability ratios for June, July, August, and 

September in the Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

24. Monthly water withdrawals and withdrawal to availability ratios for the Chipuxet 

stream-gaging station in the Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

25. Average distance, transmissivity, diffusivity, pumping rate, streamflow-depletion 

rates, and and streamflow of rivers from the Kingston and Westerly publicsupply wells and well fields used in Jenkins analysis in the Pawcatuck Basin. . . . . . . . . . . . 60

26. Average pumping rate and streamflow depletion from selected Kingston and 

Westerly public-supply wells used in Jenkins analysis during June, July, August, 

and September of 1999 in the Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

27. Average streamflow at the Chipuxet River and Pawcatuck River stream-gaging 

stations during June, July, August, and September of 1999 in the Pawcatuck 

Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

28. Pumping rate for 180 days and percent streamflow depletion divided by pumping 

rate from selected public-supply withdrawal wells for the Kingston Water District 

and Westerly Water Department used in Jenkins analysis in 1999 in the 

Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

29. Average water budget by subbasin for the Pawcatuck Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Conversion Factors, Datums, Abbreviations and 

Acronyms 

Temperature is given in degrees Fahrenheit (°F), which can be converted to degrees Celsius (°C) 

by the following equation: 

°C=(°F-32)/1.8

Multiply By To obtain

acre 4,047 square meter (m2)

acre 0.4047 hectare (ha)

foot (ft) 0.3048 meter (m)

foot squared (ft2) 0.3048 meter squared (m2)

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d)

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

mile (mi) 1.609 kilometer (km)

million gallons per day (Mgal/d) 3,785 cubic meters per day (m3/d)

million gallons per day per square mile 

(Mgal/d/mi2)

1,462.1 cubic meter per day per square 

kilometer (m3/d/km2)

square mile (mi2) 12.590 square kilometer (km2)
 vii

Transmissivity: In this report, the unit of transmissivity is foot squared per day (ft2/d).

To convert water use and availability data to cubic feet per second, multiply million gallons per 

day by 1.5466. 

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD88). 

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD83).

7Q10 7-day, 10-year flow

ABF Aquatic Base Flow

FGDC Federal Geographic Data Committee

GIS Geographic Information System

HAP Hunt–Annaquatucket–Pettaquamscutt

HUC Hydrologic Unit Code

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

MAGIC Map and Geographic Information Center

MCD Minor Civil Division

NCDC National Climatic Data Center

NEWUDS New England Water-Use Data System

NHD National Hydrography Dataset

NOAA National Oceanic and Atmospheric Administration

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

SCS Soil Conservation Service

SIC Standard Industrial Classification

STRMDEPL Streamflow depletion computer program

URI University of Rhode Island

USDA United States Department of Agriculture

USEPA United States Environmental Protection Administration

USGS United States Geological Survey

UWRI United Water of Rhode Island

WBD Watershed Boundary Dataset

WSO Weather Station Observatory

WWTF Wastewater-Treatment Facility

Estimated Water Use and Availability in the 

Pawcatuck Basin, Southern Rhode Island and 

Southeastern Connecticut, 1995–99

By Emily C. Wild and Mark T. Nimiroski

Abstract

In 1988, the Pawcatuck Basin (302.4 square miles) in 

southern Rhode Island (245.3 square miles) and southeastern 

Connecticut (57.12 square miles) was defined as a sole-source 

aquifer for 14 towns in southern Rhode Island and 4 towns 

in southeastern Connecticut. To determine water use and 

availability, the six subbasins in the Pawcatuck Basin were 

delineated on the basis of the surface- and ground-water system 

drainage areas. From 1995 through 1999, five major water 

suppliers in the basin withdrew an average of 6.768 million 

gallons per day from the aquifers. The estimated water 

withdrawals from minor water suppliers during the study period 

were 0.099 million gallons per day. Self-supplied domestic, 

industrial, commercial, and agricultural withdrawals from 

the basin averaged 4.386 million gallons per day. Water use 

in the basin averaged 7.401 million gallons per day. The 

average return flow in the basin was 7.855 million gallons 

per day, which included effluent from permitted facilities and 

self-disposed water users.

The PART program, a computerized hydrographseparation application, was used for five selected index streamgaging stations to determine water availability on the basis of 

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

base flow minus the 7-day, 10-year flow criteria, and the base 

flow minus the Aquatic Base Flow criteria at the index stations. 

The differences in the surface- and ground-water system 

drainage areas in the summer were applied to the water 

availability calculated at the index stations and subbasins. 

The base-flow contributions from sand and gravel deposits 

at the index stations were computed for June, July, August, and 

September, and applied to the percentage of surficial deposits at 

each index station. The base-flow contributions were converted 

to a per unit area at the station for the till, and for the sand and 

gravel deposits, and applied to the subbasins. The statistics used 

to estimate the gross yield of base flow, as well as subtracting 

out the two low-flow criteria, resulted in various wateravailability values at each index station, which were present in 

the subbasin after applying the per unit area rates from the index 

station. The results from the Chipuxet and Arcadia streamgaging stations were lowest in September at the 75th and 25th 

percentiles, and August flows were lowest for the summer at the 

50th percentile. For the other three index stations, September 

flows were the lowest for the summer.

Because water withdrawals and use are greater during the 

summer than other times of the year, water availability in June, 

July, August, and September was assessed and compared to 

water withdrawals in the basin and subbasins. The ratios were 

calculated by using the water-availability flow scenarios at the 

75th, 50th, and 25th percentiles for the subbasins, which are 

based on total water available from base-flow contributions 

from till deposits and sand and gravel deposits in the subbasins. 

For the study period, the withdrawals in August were higher 

than the other summer months. The ratios were close to one in 

August for the estimated gross yield and 7-day, 10-year flow 

criterion, and were close to one in September for the estimated 

Aquatic Base Flow criterion water-availability scenarios in the 

Pawcatuck Basin. The closer the ratio is to one, the closer the 

withdrawals are to the estimated water available, and the net 

water available decreases.

To determine the effects of streamflow depletion from 

continuous water withdrawals, the program STRMDEPL was 

used to simulate public wells and well fields at a constant 

pumping rate based on the 1999 summer average for each 

withdrawal, over a period of 180 days. The streamflow 

depletion was 86, 95, 93, 96, and 98 percent at 30 days for 

Kingston wells 1 and 2, Westerly well fields 1 and 2, and well 

3, respectively. 

A long-term hydrologic budget was calculated for the 

Pawcatuck Basin to identify and assess the basin and subbasin 

inflow and outflows. The water withdrawals and return flows 

used in the budget were from 1995 through 1999. For the 

hydrologic budget, it was assumed that inflow equals outflow, 

which resulted in 723.1 million gallons per day in the basin. The 

estimated inflows from precipitation and water return flow were 

99 and 1 percent in the basin, respectively. The estimated 

outflows from evapotranspiration, streamflow, and water 

withdrawals were 43, 56, and 1 percent, respectively.
2 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Introduction

In 1988, the Pawcatuck Basin was designated as a solesource aquifer by the U.S. Environmental Protection Agency 

(USEPA) for the 14 towns in southern Rhode Island and 4 

towns in southeastern Connecticut in the basin (Federal 

Registrar, 1988). Based on data from the U.S. Census Bureau, 

southern Rhode Island had the highest population growth in the 

State, ranging from a 6.3 percent increase in Westerly to a 35 

percent increase in Richmond, from the 1990 population census 

to the 2000 population census (Rhode Island Statewide 

Planning, 2001). Likewise, from 1995 through 1999, the 

estimated population growth was highest in the southern region 

in the State, ranging from a 3 percent increase in Hopkinton and 

Westerly to a 10 percent increase in Richmond (Rhode Island 

Economic Development Corporation, 2001). During the 

study period, there was an increase in the Rhode Island town 

populations in the basin, and an increase in withdrawals from 

the ground-water system. Water availability became a concern 

to the State during the 1999 drought, and further investigation 

was needed to assess water use and availability. During the 

summer of 1999, the average precipitation at the Kingston, RI, 

climatological station for June was only about 0.05 in., 

compared to the 30-year long-term average precipitation 

for June that was 3.936 in. (1971 through 2000). Because 

precipitation is a key component of ground-water infiltration 

(fig. 1), the rain deficiency, a period of little to no recharge, 

resulted in ground-water levels and streamflows dropping 

below the long-term averages throughout Rhode Island.

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

the Rhode Island Water Resources Board (RIWRB), began a 

series of water use and availability projects to better understand 

the relations between the water-use components (fig. 2) and the 

components of the hydrologic cycle (surface and ground water) 

during periods of little to no recharge. The Pawcatuck Basin 

was one of the first areas of concern to the State in the 

assessment of water use and availability because ground water 

is the principal water source for public suppliers and domestic 

users in the basin, (about 61 and 20 percent of the average 

annual water withdrawals, respectively, during the study 

period). The mission of the RIWRB is to serve as a watersourcing agency to ensure future water availability for 

residential growth and economic development for all Rhode 

Islanders (Rhode Island Water Resources Board, 2003).

Purpose and Scope

This report identifies the water-use components and 

assesses water use and availability in the Pawcatuck Basin and 

its six ground-water subbasins for periods of little to no 

recharge. To estimate water use, data were collected for the 

components of water use by ground-water subbasins for the 

towns and systems (supply and disposal) in the Pawcatuck 

Basin. The water withdrawals, users, and dischargers were 

organized and retrieved using the New England Water-Use 

Data System (NEWUDS) for the study period, calendar years 

1995 through 1999. The report presents the results of the 

calculated water availability for the six subbasins with a method 

of determining ground-water discharge during streamflowrecession periods in the summer. To assess the streamflow and 

ground-water interactions, a streamflow-depletion program was 

run on five of the public supply wells and well fields near the 

streams. A basin water budget is presented in this report, and it 

was completed in order to summarize the components of the 

hydrologic cycle based on the long-term period of record and 

selected water-use components for the study period.
Introduction 3

GROUND-WATER INFILTRATION

THE MODIFIED HYDROLOGIC CYCLE

SURFACE WATER

RIVERS AND PONDS

GROUND-WATER DISCHARGE

(BASE FLOW)

SUBSURFACE:

GROUND-WATER AQUIFER

(BEDROCK OR STRATIFIED 

SAND AND GRAVEL)

DIRECT RUNOFF

ATMOSPHERE

LAND SURFACE

PRECIPITATIONPRECIPITATION

EVAPOTRANSPIRATIONEVAPOTRANSPIRATION

Figure 1. The modified hydrologic cycle.
4 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

 Water Use

(Ground Water

and Surface Water)

Water Withdrawals

Water Purification

Non-Account 

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)

Non-Account 

Water Use

Figure 2. The components of water use.
Introduction 5

Previous Investigations

The U.S. Geological Survey has been collecting 

streamflow data through partial and continuous stream-gaging 

stations for the Pawcatuck Basin for over 60 years, and has been 

monitoring ground-water levels for more than 50 years. The 

data collected have been used for numerous hydrologic studies 

in the basin and its subbasins. Many studies have investigated 

the ground-water and surface-water resources and the water 

quality of the Pawcatuck Basin and its subbasins. The 

Pawcatuck is within the Ashaway, Carolina, Coventry Center, 

Hope Valley, Kingston, Oneco, Slocum, Voluntown, Watch 

Hill, and Wickford USGS quadrangles. The USGS has 

published these quadrangles in detailed thematic maps 

describing the surficial and bedrock geology (Feininger, 1962, 

1965a, 1965b, 1965c; Hardwood, 1971a, 1971b; Moore, 1958, 

1959, 1967; Power, 1957, 1959; and Schafer, 1961, 1965, 

1968). In addition, the USGS has published basin studies that 

provide information on hydrologic characteristics of the 

surficial deposits (till and stratified sand and gravel deposits), 

ground-water models, precipitation, and streamflows in the 

Open-File Report, Professional Paper, Water-Resources 

Investigations Report, and Water-Supply Paper series (Allen 

and others, 1966; Barlow and Dickerman, 2001; Cervione and 

others, 1993; Crosby, 1905; DeSimone and Ostiguy, 1999; 

Dickerman, 1984; Dickerman and Ozbilgin, 1985; Dickerman 

and others 1990; Dickerman and others, 1997; Gonthier and 

others, 1974; Johnston and Dickerman, 1985; and Morrissey, 

1989). 

Previous investigations completed in cooperation with the 

Rhode Island Water Resources Board have been published in 

the Geological Bulletin, Ground-Water Map, Hydrologic 

Bulletin, Scientific Contribution and Water Information Series 

Report series. The Geologic Bulletins provide well records, 

lithologic logs, water-quality assessments, hydrologic 

characteristics of the surficial deposits (till and stratified sand 

and gravel deposits), and water-table information, and the 

information is provided by USGS quadrangle (Allen, 1953; 

Allen, 1956; Allen and others, 1963; Bierschenk, 1956; and 

Lang, 1961). Ground-Water Maps provide bedrock contours, 

water-table altitudes, well locations, and till and stratified sand 

and gravel deposits, and the information is provided by USGS 

quadrangle (Bierschenk and Hahn, 1959; Hahn, 1959; Johnson, 

1961a; Johnson, 1961b; Johnson and others, 1960; LaSala and 

Hahn, 1960; Mason and Hahn, 1960; and Randal and others, 

1960). Hydrologic Bulletins describe lithologic logs and 

historical aquifer tests (Lang and others, 1960). The Scientific 

Contribution series reports well records, and information on 

bedrock and surficial deposits (Allen and Jeffords, 1948). 

Water Information Series Reports describe the hydrologic 

characteristics by basin or subbasin (Dickerman, 1976; 

Dickerman and Johnston, 1977; Dickerman and Silva, 1980; 

Dickerman and others, 1989; Dickerman and Bell, 1993; and 

Kliever, 1995). 

In addition to studies pertaining to surficial deposits in 

the basin and subbasins, information has been collected 

and compiled for the water use in the Pawcatuck Basin and 

statewide assessments (Craft and others, 1995; Horn, 2000; 

Horn and Craft, 1991; and Medalie, 1996). Information on 

major public water suppliers has been collected through written 

and oral communication from the Rhode Island Water 

Resources Board and major public water suppliers. The 

suppliers also prepare water-supply management plans that 

are submitted to the Rhode Island Water Resources Board, as 

a part of the State’s Water Supply Systems Management Plan. 

Information on public disposal was collected (oral and written 

communication) from wastewater assessments that have been 

completed and submitted to the Rhode Island Department of 

Environmental Management (RIDEM), Office of Water 

Resources.

Acknowledgments

Original water-use withdrawal and discharge data were 

collected from the public water-supply districts, the RIDEM 

Office of Water Resources, individual wastewater-discharge 

facilities, and the Rhode Island Water Resources Board 

(RIWRB). The authors thank the following individuals for 

assisting in the data-collection process: Henry Meyer, Kingston 

Water District; the late Steve Pucino, University of Rhode 

Island (URI); Paul Corian, Westerly Water Department; Ron 

Richard, Richmond Water Supply System; Stanley Knox, 

United Water of Rhode Island (UWRI); Harold Storrs, 

Stonington Wastewater Facility; Aaron Mello, RIDEM Office 

of Water Resources; Clay Commons, Rhode Island Department 

of Health, Office of Drinking Water Quality; Amanda Aretz, 

Andrew Thorpe, and Carol Gannon, formerly of the U.S. 

Geological Survey; and Dennis Ventetuolo and Tomas 

Smieszek, U.S. Geological Survey.
6 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

The Pawcatuck Basin

The Pawcatuck Basin is in southern Rhode Island and 

southeastern Connecticut (fig. 3). Land area in the basin totals 

approximately 302.4 mi2, approximately 245.3 mi2 of which is 

in Rhode Island and approximately 57.12 mi2 of which is in 

Connecticut. The basin includes 10 Rhode Island towns and 4 

Connecticut towns that are partially within the study area. In 

1990, the basin population was approximately 61,481, and the 

estimated population during the study period was 66,528 

(table 1). The Pawcatuck Basin is mostly hilly, with higher 

altitudes in the northwest. In Rhode Island, the highest altitude 

in the basin is Bald Hill at 629 ft in West Greenwich. The 10 

principal ground-water reservoirs, or aquifers, in the basin are 

the Mink, Chipuxet, Usquepaug–Queen, Beaver–Pasquiset, 

Upper Wood, Lower Wood, Ashaway, Shunock, Bradford, and 

Westerly ground-water reservoirs (fig. 4). Ground-water 

aquifers are defined as areas of stratified sand and gravel 

deposits with a saturated thickness greater than 40 ft. For 

this study, the Pawcatuck Basin has been grouped into six 

subbasins: the Chipuxet, Usquepaug–Queen, Beaver–

Pasquiset, Upper Wood, Lower Wood, and Lower Pawcatuck 

subbasins (fig. 4), and are based on the ground-water drainage 

areas. 

Precipitation and temperature data for the climatological 

station at Kingston, RI, on the University of Rhode Island (URI) 

campus and the Providence WSO climatological station at the 

airport in Warwick, RI, were compiled 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). The total annual precipitation at the Kingston, RI, 

station from 1971 through 2000 was 49.94 in., and the average 

precipitation ranged from 3.308 in. (July) to 4.400 in. (August) 

for the summer. The total annual precipitation at the Kingston 

climatological station for the study period was 53.11 in., and the 

average monthly precipitation ranged from 2.728 in. (July) to 

4.474 in. (September) for the summer. At the Providence WSO 

climatological station in Warwick, RI, the average annual 

precipitation for the 30-year period, 1971 through 2000, was 

46.46 in., and the 30-year average monthly precipitation ranged 

from 3.169 in. (July) to 3.904 in. (August) for the summer. The 

average annual precipitation at Providence WSO for the study 

period was 43.91 in., and the average monthly precipitation 

ranged from 1.978 in. (July) to 4.014 in. (September) for the 

summer. The total annual temperature at the Kingston, RI, 

station from 1971 through 2000 was 49.94°F, and the average 

temperature ranged from 62.72°F (September) to 71.06°F 

(July) for the summer. The average annual temperature at the 

Kingston climatological station for the study period was 

50.91°F, and the average monthly temperatures ranged from 

63.74°F (September) to 71.88°F (July) for the summer. At the 

Providence WSO climatological station in Warwick, RI, the 

average annual temperature for the 30-year period, 1971 

through 2000, was 51.13°F, and the 30-year average monthly 

temperatures ranged from 63.99°F (September) to 73.37°F 

(July) for the summer. The average annual temperature at 

Providence WSO for the study period was 51.84°F, and 

the average monthly temperatures ranged from 64.74°F 

(September) to 74.14°F (July) for the summer. Precipitation 

and temperature data for the climatological stations are 

summarized in table 2.

Land use was calculated by merging the Rhode Island 

Geographic Information Systems (RIGIS) land-use coverages 

and the Connecticut Map and Geographic Information Center 

(MAGIC) coverages with the subbasin-boundary coverages. 

Land-use area was used as a tool to aggregate commercial, 

industrial, and agricultural water-use estimates into the 

applicable towns, subbasins, and basin (table 3). For the 

Pawcatuck Basin, the total land-use area for commercial, 

industrial, and agricultural was 1.219 mi2, 1.137 mi2, and 

25.98 mi2, respectively. The commercial land-use area ranged 

from 0.060 mi2 in the Lower Wood subbasin to 0.666 mi2 in the 

Lower Pawcatuck subbasin. The industrial land-use area ranged 

from 0.011 mi2 in the Usquepaug–Queen subbasin to 0.779 mi2

in the Lower Pawcatuck subbasin. The agricultural land-use 

area ranged from 2.008 mi2 in the Beaver–Pasquiset subbasin to 

8.239 mi2 in the Lower Pawcatuck subbasin. For water-supply 

districts, land-use area was used to aggregate the water-use 

categories by basin and subbasin (table 4). The total land-use 

area by public-supply district for commercial, industrial, 

and agricultural was 0.646 mi2, 0.143 mi2, and 1.416 mi2, 

respectively, within the Pawcatuck Basin. The commercial 

land-use area ranged from 0.006 mi2 to 0.536 mi2, for the 

United Water of Rhode Island (UWRI) and Westerly Water 

Department service areas in the Pawcatuck Basin, respectively. 

The industrial land-use area ranged from 0.022 mi2 to 

0.097 mi2, for the Richmond Water Supply and Westerly Water 

Department service areas in the Pawcatuck Basin, respectively. 

The agricultural land-use area ranged from 0.116 mi2 to 

0.841mi2, for the Richmond Water Supply and Westerly Water 

Department service areas in the Pawcatuck Basin, respectively. 
The Pawcatuck Basin 7

0 1 2 MILES

0 1 2 KILOMETERS

Glen Rock

 Reservoir

WINDHAM

NEW LONDON

KENT

WASHINGTON

COVENTRY

FOSTER

SCITUATE

CRANSTON

WARWICK

WEST

WARWICK

EAST

GREENWICH

PRESTON

GRISWOLD

VOLUNTOWN

NORTH

STONINGTON

STONINGTON

WESTERLY CHARLESTOWN

NARRAGANSETT

TRIBAL

LAND

RICHMOND

HOPKINTON

SOUTH

KINGSTOWN

West

Kingston

NORTH

KINGSTOWN

EXETER

WEST

GREENWICH

STERLING

Westerly

Pawcatuck Village

NARRAGANSETT

Kingston

PLAINFIELD

BROOKLYN KILLINGLY

71O55' 71O

30'

41O40'

41O20'

Shunock River

Meadow 

 Brook

Qu e e ns Fort Brook

River

Flat

Green Fall River

Wyassup Brook

Chickasheen R.

Worden

Pond

Wood River

Mink R.

PawcatuckRiv er

Wood

River

Beaver

River

Chipuxet R.

Block Island Sound

Rhode

Island

Sound

Little Narragansett Bay

Pasquiset R.

Usquepaug

R.

Narragansett Bay

Queen

River

LOWER WOOD

UPPER WOOD

PAWTUXET 

BASIN 

CHIPUXET

NARRAGANSETT BAY 

DRAINAGE BASIN

USQUEPAUGQUEEN

LOWER PAWCATUCK

BEAVER - PASQUISET

SOUTH COASTAL DRAINAGE BASIN

PAWCATUCK BASIN

QUINEBAUG BASIN

RHODE ISLAND INDEX MAP

map area shown

MASSACHUSETTS

RHODE ISLAND

71o15'

42o

00'

71o

45'

0 10 20 MILES

0 10 20 KILOMETERS

Block Island, RI

CONNECTICUT

Narragansett Bay

41o30'

Rhode Island 

Sound

Block Island 

Sound

Long Island Sound

CONN

RI

EXPLANATION

MAJOR BASIN

PAWCATUCK STUDY AREA BASIN

SUBBASINS WITHIN PAWCATUCK BASIN

Base from U.S. Geological Survey, Connecticut MAGIC, and Rhode Island GIS data sets

Rhode Island state plane, 5176 fipzone

Horizontal datum is NAD 83

Source map scale 1:300,000

Figure 3. The Pawcatuck Basin and subbasins, southern Rhode Island and southeastern Connecticut.
8 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

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

disposal populations in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99.

[All towns are in Rhode Island unless otherwise noted. Total populations in Rhode Island 1990: From Rhode Island Geographic Information System (1991). 

Estimated 1995–99 population: From the Rhode Island Economic Development Corporation (2000). Total populations in Connecticut from 1990 are from the 

University of Connecticut Center for Geographic Information and Analysis (2000). Estimated 1995–99 population from the Connecticut Department of Health 

(1995, 1996, 1997, 1998, and 1999). --, not applicable]

Towns

Population Estimated 1995–99 population

1990 Estimated

1995–99

Supply Disposal

Public Self Public Self

Chipuxet Subbasin

Charlestown 239 264 34 230 28 236

Exeter 812 880 92 788 57 823

North Kingstown 668 728 596 132 7 721

Richmond 266 330 14 316 -- 330

South Kingstown 9,505 10,188 7,193 2,995 5,985 4,203

Subbasin total 11,490 12,390 7,929 4,461 6,077 6,313

Usquepaug–Queen Subbasin

East Greenwich 37 38 24 14 2 36

Exeter 2,866 3,107 164 2,943 92 3,015

North Kingstown 133 145 131 14 9 136

Richmond 652 808 78 730 -- 808

South Kingstown 434 465 15 450 -- 465

West Greenwich 212 240 -- 240 -- 240

Subbasin total 4,334 4,803 412 4,391 103 4,700

Beaver–Pasquiset Subbasin

Charlestown 1,403 1,553 162 1,391 135 1,418

Exeter 266 288 2 286 -- 288

Richmond 1,880 2,330 178 2,152 -- 2,330

South Kingstown 27 29 13 16 3 26

Subbasin total 3,576 4,200 355 3,845 138 4,062

Upper Wood Subbasin

Coventry 64 67 1 66 -- 67

Exeter 1,049 1,138 136 1,002 39 1,099

Hopkinton 1,938 2,189 150 2,039 108 2,081

North Stonington, CT -- -- -- -- -- --

Richmond 902 1,118 110 1,008 -- 1,118

Sterling, CT 380 444 45 399 70 374

Voluntown, CT 190 203 24 179 8 195

West Greewich 1,103 1,246 63 1,183 34 1,212

Subbasin total 5,626 6,405 529 5,876 259 6,146

Lower Wood Subbasin

Charlestown 1,223 1,354 40 1,314 6 1,348

Hopkinton 1,460 1,650 233 1,417 110 1,540

North Stonington, CT -- -- -- -- -- --

Richmond 1,650 2,045 123 1,922 -- 2,045

Voluntown, CT -- -- -- -- -- --

Subbasin total 4,333 5,049 396 4,653 116 4,933
The Pawcatuck Basin 9

Lower Pawcatuck Subbasin

Charlestown 946 1,047 92 955 18 1,029

Hopkinton 3,473 3,924 337 3,587 125 3,799

North Stonington, CT 3,611 3,617 876 2,741 102 3,515

Stonington, CT 5,007 4,864 4,480 384 3,187 1,677

Voluntown, CT 194 207 2 205 -- 207

Westerly 18,891 20,022 19,371 651 12,862 7,160

Subbasin total 32,122 33,681 25,158 8,523 16,294 17,387

Pawcatuck Basin

Basin total 61,481 66,528 34,779 31,749 22,987 43,541

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

disposal populations in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99.—Continued

[All towns are in Rhode Island unless otherwise noted. Total populations in Rhode Island 1990: From Rhode Island Geographic Information System (1991). 

Estimated 1995–99 population: From the Rhode Island Economic Development Corporation (2000). Total populations in Connecticut from 1990 are from the 

University of Connecticut Center for Geographic Information and Analysis (2000). Estimated 1995–99 population from the Connecticut Department of Health 

(1995, 1996, 1997, 1998, and 1999). --, not applicable]

Towns

Population Estimated 1995–99 population

1990 Estimated

1995–99

Supply Disposal

Public Self Public Self

Table 2. Summary of climatological data pertinent to the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut.

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

1971–2000. WSO, weather station observatory; °F, degrees Fahrenheit; in., inch]

Climatological station Period of record Average temperature (°F)

June July August September Annual 

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 WSO Airport, 

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

Climatological station Period of record Average precipitation (in.) Annual total

(in.) June July August September

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 WSO Airport, 

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
10 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

0 1 2 MILES

0 1 2 KILOMETERS

WINDHAM

NEW LONDON

KENT

WASHINGTON

COVENTRY

FOSTER SCITUATE

CRANSTON

WEST WARWICK

WARWICK

EAST

GREENWICH

PRESTON

GRISWOLD

VOLUNTOWN

NORTH

STONINGTON

STONINGTON

WESTERLY CHARLESTOWN

NARRAGANSETT

TRIBAL LAND

RICHMOND

HOPKINTON

SOUTH

KINGSTOWN

NORTH

KINGSTOWN

EXETER

WEST

GREENWICH

STERLING

NARRAGANSETT

PLAINFIELD

BROOKLYN KILLINGLY

CONN

RI

71O55' 71O

30'

41O40'

41O20'

LOWER WOOD

UPPER WOOD

CHIPUXET

USQUEPAUGQUEEN

LOWER PAWCATUCK

BEAVER - PASQUISET

PAWTUXET 

BASIN NARRAGANSETT BAY 

DRAINAGE BASIN

SOUTH COASTAL DRAINAGE BASIN

PAWCATUCK BASIN

QUINEBAUG BASIN

V

U

T

W

S

M-O

P-R

G-H C-F

L

I-K

A,B

Upper Wood Aquifer

Lower Wood Aquifer

Usquepaug-Queen

Aquifer

Ashaway Aquifer

Westerly Aquifer

Bradford Aquifer

Chipuxet Aquifer

Mink Aquifer

Beaver-Pasquiset Aquifer

Shunock Aquifer

CONN

RI

Base from U.S. Geological Survey, Connecticut MAGIC, and Rhode Island GIS data sets

Rhode Island state plane, 5176 fipzone

Horizontal datum is NAD 83

Source map scale 1:300,000

Sand and gravel

Till and bedrock

Area where ground water drains east to the Hunt-AnnaquatucketPettaquamscutt (HAP) stream-aquifer system, which is part of the Narragansett Bay Drainage Basin

Ground-water 

aquifer (reservoir)

HYDROGEOLOGY WELLS

Major public-supply well 

and identifier–see table 8

for well and well field

Subbasins within descriptions Pawcatuck Basin

Major basin

Pawcatuck study area

Minor public-supply well

X

HYDROLOGIC BOUNDARY

EXPLANATION

Figure 4. Aquifers and selected withdrawal wells for the subbasins in the Pawcatuck Basin, southern Rhode Island and 

southeastern Connecticut, 1995–99.
The Pawcatuck Basin 11

Table 3. Town land area and land-use area by category in the subbasins of the Pawcatuck Basin, southern Rhode Island and 

southeastern Connecticut.

[Land-use areas were estimated by using the coverage from the Rhode Island Geographic Information System, 1995a. All towns are in Rhode Island unless 

otherwise noted. mi2, square mile; <0.001, values not included in town and subbasin totals; <, actual value is less than value shown; --, not applicable]

Towns

Land

area

(mi2)

Land-use area by category (mi2)

CommercialIndustrialAgricultural

Chipuxet Subbasin

Charlestown 1.040 -- -- 0.046

Exeter 6.723 0.025 0.019 .712

North Kingstown 3.057 .001 .014 1.051

Richmond 1.919 .009 -- .709

South Kingstown 24.19 .084 .088 2.685

Subbasin total 36.93 0.119 0.121 5.203

Usquepaug–Queen Subbasin

East Greenwich 0.096 -- -- --

Exeter 24.21 0.046 0.003 2.838

North Kingstown .318 .016 -- .129

Richmond 4.503 .006 -- .350

South Kingstown 3.599 .002 -- .726

West Greenwich 3.374 -- .008 .118

Subbasin total 36.10 0.070 0.011 4.161

Beaver–Pasquiset Subbasin

Charlestown 6.782 0.059 0.033 0.498

Exeter 2.334 .043 -- .110

Richmond 13.16 .013 .016 1.400

South Kingstown .190 -- -- --

Subbasin total 22.47 0.115 0.049 2.008

Upper Wood Subbasin

Coventry 0.872 -- -- <0.001

Exeter 20.18 0.018 0.019 .590

Hopkinton 13.45 .033 .022 .938

North Stonington, CT .003 -- -- --

Upper Wood Subbasin—Continued

Richmond 6.543 0.098 0.039 0.286

Sterling, CT 5.819 -- -- .517

Voluntown, CT 3.365 -- .007 .159

West Greenwich 22.75 .040 .018 .965

Subbasin total 72.98 0.189 0.105 3.455

Lower Wood Subbasin

Charlestown 8.633 0.004 0.033 0.379

Hopkinton 13.14 .011 .011 1.022

North Stonington, CT .007 -- -- --

Richmond 14.62 .045 .028 1.516

Voluntown, CT .017 -- -- --

Subbasin total 36.42 0.060 0.072 2.917

Lower Pawcatuck Subbasin

Charlestown 8.692 0.007 -- 0.106

Hopkinton 17.55 .117 0.032 1.832

North Stonington, CT 38.28 -- .530 4.322

Stonington, CT 5.125 -- .082 .537

Voluntown, CT 4.504 -- .021 .082

Westerly 23.30 .542 .114 1.360

Subbasin total 97.45 0.666 0.779 8.239

Pawcatuck Basin

Basin total 302.4 1.219 1.137 25.98

Towns

Land

area

(mi2

)

Land-use area by category (mi2)

CommercialIndustrialAgricultural

i
12 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Table 4. Land-use area and percent land-use area by water-supply district for the subbasins in the Pawcatuck Basin study area and 

areas outside of the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut.

[Land-use areas for the water-supply districts were estimated from coverages from the Rhode Island Geographic Information System, 1995a,b. mi2, square mile; 

--, not applicable]

Water supplier Subbasin of well 

withdrawal

Land-use area by category in the

Pawcatuck Basin (mi2)

Land-use area by category outside of the 

Pawcatuck Basin (mi2)

Commercial Industrial Agricultural Commercial Industrial Agricultural

Kingston Water District Chipuxet 0.024 0.024 0.126 0.031 0.031 0.082

United Water of Rhode Island Chipuxet .006 -- .333 .441 .067 1.095

Richmond Water Supply Upper Wood .080 .022 .116 -- -- --

Westerly Water Division Lower Pawcatuck .536 .097 .841 .154 -- .224

Water supplier Subbasin of well 

withdrawal 

Percent land use in the

Pawcatuck Basin

Percent land use outside of the 

Pawcatuck Basin

Commercial Industrial Agricultural Commercial Industrial Agricultural

Kingston Water District Chipuxet 44 44 60 56 56 40

United Water of Rhode Island Chipuxet 1 -- 23 99 100 77

Richmond Water Supply Upper Wood 100 100 100 -- -- --

Westerly Water Division Lower Pawcatuck 78 100 79 22 -- 21

Pawcatuck Subbasins

Because this study is based on the water availability in the 

sand and gravel aquifers, the USGS delineated the six subbasins 

of the Pawcatuck Basin based on the surface-water drainage 

areas contributing to the stratified sand and gravel deposits, 

and areas contributing to the upland till deposits (table 5). 

Barlow and Dickerman (2001) found that portions of the 

ground-water boundary differs from the surface-water 

boundary in the Chipuxet and Usquepaug–Queen subbasins. 

In these portions, the surface water drains to the Pawcatuck 

Basin, whereas the ground water drains to the Hunt–

Annaquatucket–Pettaquamscutt stream-aquifer system. 

The differences in the land area and surficial deposits within 

the subbasins are presented in table 5. During a concurrent 

study in the Usquepaug–Queen subbasin, it was estimated 

that approximately 25 percent of the water within the 

subbasin drains to the Pawcatuck Basin during the wet 

season (P.J. Zarriello, oral commun., 2003). The groundwater flow boundary, therefore, was used for determining 

water availability for the summer in the Chipuxet and 

Usquepaug–Queen subbasins (table 5). Based on the surfacewater drainage boundaries, approximately 37.1 percent of the 

Pawcatuck Basin is stratified sand and gravel deposits. Based 

on the ground-water boundaries, approximately 36.9 percent 

of the Pawcatuck Basin is stratified sand and gravel deposits 

(table 5). Among the sand and gravel deposits, the areas of 

saturated thickness that are greater 40 ft are referred to as 

ground-water reservoirs, or aquifers (table 5). 

The USGS subbasin boundaries delineated for this study 

area differ from the cataloging units defined by the Watershed 

Boundary Dataset (WBD) delineations from the Natural 

Resources Conservation Service (NRCS). Naming conventions 

are another difference in the comparison between the 

Pawcatuck Basin study subbasins and the 10-digit and 12-digit 

cataloging units. Land area and naming convention 

comparisons are presented in table 6. The WBD spatial data 

primarily define the surface water features, and delineations are 

defined by using the criteria recommended by the Federal 

Geographic Data Committee (FGDC) in 2002. Additional 

information regarding the FGDC definitions, process, and 

current progress can be found at the FGDC Web site: ftp://ftpfc.sc.egov/NCGC/products/watershed/hu-standards.doc/.
The Pawcatuck Basin 13

1The difference between the surface-water and ground-water drainage areas in the Usquepaug–-Queen subbasin is 3.03 mi2, where the surficial geology is 

1.28 mi2 sand and gravel deposits, and 1.75 mi2 till deposits (P.M. Barlow, U.S. Geological Survey, oral commun., 2003).

2The difference between the surface-water and ground-water drainage areas in the Chipuxet subbasin is 0.95 mi2, where the surficial geology is 

0.80 mi2 sand and gravel deposits, and 0.15 mi2 till deposits (P.M. Barlow, U.S. Geological Survey, oral commun., 2003).

Table 5. Surface-water and ground-water drainage areas, the percentage of sand and gravel deposits and till deposits, and the 

ground-water reservoirs for the subbasins in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut.

[Ground-water reservoir, or aquifer, is the area of stratified sand and gravel deposits with a saturated thickness of at least 40 feet. mi2, square miles]

Subbasin

Surface-water drainage areas Ground-water drainage areas Ground-water 

reservoir

(aquifer) area

(mi2)

Land area

(mi2)

Percent

sand and

gravel deposits

Percent

till deposits

Land area

(mi2)

Percent

sand and

gravel deposits

Percent

till deposits

Chipuxet1 36.93 59.4 40.6 35.98 58.7 41.3 4.256

Usquepaug–Queen2 36.10 34.2 65.8 33.07 33.5 66.5 2.612

Beaver–Pasquiset 22.47 44.4 55.6 22.47 44.4 55.6 1.630

Upper Wood 72.98 26.2 73.8 72.98 26.2 73.8 1.757

Lower Wood 36.42 47.5 52.5 36.42 47.5 52.5 4.075

Lower Pawcatuck 97.45 32.2 67.8 97.45 32.2 67.8 3.912

Basin total 302.4 37.1 62.9 302.4 36.9 63.1 18.24

Table 6. Defined subbasins in the Pawcatuck Basin study area in Rhode Island compared to the 10-digit and 12-digit hydrologic units 

from the Natural Resources Conservation Service, Watershed Boundary Dataset in Rhode Island.

[The total land area in Rhode Island, 309.1 mi2, for the Watershed Boundary Dataset for the Pawcatuck Basin 8-digit (01090005) hydrologic unit includes the 

South Coastal Drainage Basin, 56.40 mi2, and Block Island, 7.752 mi2, which are outside of the study area. mi2, square mile]

Pawcatuck Basin study area in 

Rhode Island Watershed Boundary Dataset for Pawcatuck Basin in Rhode Island

Subbasins

Drainage

areas

(mi2)

 10-digit 

hydrologic unit Number 

Drainage

areas

(mi2)

 12-digit 

hydrologic unit Number 

Drainage

areas

(mi2)

Chipuxet

Usquepaug–Queen 

Beaver–Pasquiset 

Upper Wood 

Lower Wood 

Lower Pawcatuck

36.93

36.10

22.47

63.80

36.40

49.50

Wood River 0109000501 79.70 Upper Wood River 010900050101 52.61

Lower Wood River 010900050102 27.09

Upper Pawcatuck 

River

0109000502 153.3 Chipuxet River 010900050201 25.79

Queen River 010900050202 36.63

Beaver River 010900050203 12.50

Upper Pawcatuck River 010900050204 21.61

Pawcatuck mainstem 010900050205 56.82

Lower Pawcatuck 

River

0109000503 12.52 Ashaway River 010900050301 4.729

Total Pawcatuck Basin 

study area in Rhode 

Island .............................

Lower Pawcatuck River 010900050303 7.792

Total 10-digit hydrologic 

245.2 unit........................................ 245.5 Total 12-digit hydrologic unit .............. 245.6
14 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

The Chipuxet subbasin (36.93 mi2 drainage area) is in the 

eastern section of the Pawcatuck Basin in Rhode Island. Towns 

in the subbasin include Charlestown, Exeter, North Kingstown, 

Richmond, and South Kingstown (fig. 3). Land areas and landuse areas by category are summarized in tables 3 and 4. The 

Chipuxet River (considered the head of the Pawcatuck Basin) 

flows southwestward before it flows into the main stem of the 

Pawcatuck River. The Mink and Chipuxet Rivers flow into 

Worden Pond in South Kingstown, at which point the river is 

defined as the Pawcatuck River. The Mink and Chipuxet 

aquifers are ground-water sources for water suppliers in the 

subbasin (fig. 4); the Kingston Water District and University of 

Rhode Island (URI) withdraw from the Chipuxet aquifer, and 

United Water of Rhode Island (UWRI) withdraws from the 

Mink aquifer. The subbasin is 59 percent sand and gravel; 

however, included in this scenario is the 8.77 mi2 (24 percent) 

of wetlands in the subbasin. There is one continuous streamgaging station in the subbasin, the Chipuxet River at West 

Kingston, RI (station 01117350), with more than 27 years 

of surface-water data (fig. 5). The extent of sand and gravel 

deposits upstream of the stream-gaging station is 43 percent. In 

a small section in the northern area of the Chipuxet subbasin, 

the surface- and ground-water drainage boundaries do not 

overlap (fig. 3); the surface water drains to the Pawcatuck River 

to the southwest, and the ground water in approximately 

0.95 mi2 of the area in the subbasin discharges to the Hunt–

Annaquatucket–Pettaquamscutt (HAP) aquifer system to the 

northeast (Barlow and Dickerman, 2001). The area of the 

ground-water drainage boundary discharging to the HAP is 

approximately 0.80 mi2 sand and gravel deposits and 0.15 mi2

till. This difference is addressed in this report for determining 

water availability during the summer because the amount of 

ground-water discharge available at the Chipuxet streamgaging station was based on the amount of sand and gravel 

deposits and till deposits within the ground-water drainage 

boundary.

Because the Chipuxet subbasin is an area of concern to 

State and local municipalities, further analysis of water use and 

availability was completed in the area upstream of the Chipuxet 

stream-gaging station (fig. 5). In addition to assessing the 

defined subbasins, water withdrawals and water availability 

were calculated for the area upstream of the station. In 

particular, an assessment was made to determine the net 

availability in this specific area—the ratio of water withdrawals 

to the water available at the Chipuxet stream-gaging station for 

June, July, August, and September. This assessment will be 

discussed in more detail in other sections of this report. 

The Usquepaug–Queen subbasin (36.10 mi2 drainage 

area) is in the northeastern section of the Pawcatuck Basin 

in Rhode Island. The towns in the subbasin include East 

Greenwich, Exeter, North Kingstown, Richmond, South 

Kingstown, and West Greenwich (fig. 3). Land areas and landuse areas by category are summarized in tables 3 and 4. The 

Queen River flows south to Glen Rock Reservoir, and the 

Usquepaug River flows south from Glen Rock Reservoir to its 

confluence with the Pawcatuck River. The Usquepaug–Queen 

aquifer (fig. 4) is the primary source of ground water for the 

self-supplied water users within the subbasin. Approximately 

34 percent of the subbasin is stratified sand and gravel deposits. 

There are two continuous stream-gaging stations in the 

subbasin (fig. 5), the Queen River at Liberty Road at Liberty, RI 

(station 01117370), which has 4 years of surface-water data 

(water years 1999–2002); and the Usquepaug River near 

Usquepaug, RI (station 01117420), which has more than 

26 years of surface-water data. For this study, the Usquepaug 

stream-gaging station defines the subbasin confluence with 

the main stem of the Pawcatuck River. In a small section in 

the northern portion of the Usquepaug–Queen subbasin, 

the surface- and ground-water drainage boundaries do not 

overlap; the surface water drains to the Pawcatuck River to the 

southwest, and approximately 3.03 mi2 of the ground water in 

the subbasin discharges to the HAP aquifer system to the east 

(Barlow and Dickerman, 2001), as illustrated in figure 3. The 

area of the ground-water drainage boundary that discharges to 

the HAP is approximately 1.28 mi2 sand and gravel deposits 

and 1.75 mi2 till. This difference is addressed in this report for 

determining water availability during the summer because the 

amount of ground-water discharge available at the Usquepaug 

River stream-gaging station was based on the amount of sand 

and gravel deposits within the ground-water drainage boundary.

The Beaver–Pasquiset subbasin (22.47 mi2 drainage area) 

is in the eastern section of the Pawcatuck Basin in Rhode Island. 

The towns in the subbasin include Charlestown, Exeter, 

Richmond, and South Kingstown (fig. 3). Land areas and landuse areas by category are summarized in tables 3 and 4. The 

Beaver River flows south, and the Pasquiset River flows north 

into the Pawcatuck River, approximately in the center of the 

subbasin. The Beaver–Pasquiset aquifer (fig. 4) is the groundwater source for self-supplied water users in the subbasin. There 

is one continuous stream-gaging station (fig. 5), the Beaver 

River near Usquepaug, RI (station 01117468), which has more 

than 26 years of surface-water data. The surficial deposits are 

approximately 44 percent sand and gravel in the subbasin, and 

are approximately 26 percent sand and gravel in the area 

upstream of the stream-gaging station 01117468. 
The Pawcatuck Basin 15

0 1 2 MILES

0 1 2 KILOMETERS

Glen Rock

 Reservoir

WINDHAM

NEW LONDON

KENT

WASHINGTON

COVENTRY

FOSTER SCITUATE

CRANSTON

WEST WARWICK

WARWICK

EAST

GREENWICH

PRESTON

GRISWOLD

VOLUNTOWN

NORTH

STONINGTON

STONINGTON

WESTERLY CHARLESTOWN

NARRAGANSETT

TRIBAL

LAND

RICHMOND

HOPKINTON

SOUTH

KINGSTOWN

West

Kingston

NORTH

KINGSTOWN

EXETER

WEST

GREENWICH

STERLING

Westerly

Pawcatuck Village

NARRAGANSETT

Kingston

PLAINFIELD

BROOKLYN KILLINGLY

CONN

RI

71O55' 71O

30'

41O40'

41O20'

Shunock River

Meadow 

 Brook

Qu e e ns Fort Brook

River

Flat

Green Fall River

Wyassup Brook

Chickasheen R.

Worden

Pond

Wood River

W

Mink R. ood

River

Beaver

River

Chipuxet R.

Block Island Sound

Rhode

Island

Sound Little Narragansett Bay

Pasquiset R.

Narragansett Bay

Usquepaug

R. Queen

River

Pawcatuck River

LOWER WOOD

UPPER WOOD

PAWTUXET 

BASIN 

CHIPUXET

NARRAGANSETT BAY 

DRAINAGE BASIN

USQUEPAUGQUEEN

LOWER PAWCATUCK BEAVER - PASQUISET

SOUTH COASTAL DRAINAGE BASIN

PAWCATUCK BASIN

QUINEBAUG BASIN

01117800

01118000

01118500

01117500

01117420

01117350

01117468

5

7

South

Kingstown

Regional

WWTF

discharge

NarragansettScarborough

WWTF

discharge Westerly

WWTF

discharge Stonington

WWTF

discharge

Ladd

School

8

6

4

3

8

10

9

11

2

1

CONN

RI

Base from U.S. Geological Survey, Connecticut MAGIC, and Rhode Island GIS data sets

Rhode Island state plane, 5176 fipzone

Horizontal datum is NAD 83

Source map scale 1:300,000

EXPLANATION

2

STREAM-GAGING STATION AND NUMBER

RHODE ISLAND POLLUTANT DISCHARGE

SYSTEM (RIPDES) SITE AND

NUMBER—See table 15

WASTEWATER-TREATMENT 

FACILITY (WWTF) DISCHARGE

01117800

MAJOR BASIN BOUNDARY

STUDY AREA BOUNDARY

SUBBASINS WITHIN 

PAWCATUCK BASIN

Figure 5. Stream-gaging stations and wastewater-treatment facilities associated with the Pawcatuck Basin, southern 

Rhode Island and southeastern Connecticut, 1995–99.
16 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

The Upper Wood subbasin (72.98 mi2 drainage area) is in 

the northwestern section of the Pawcatuck Basin in Rhode 

Island (63.79 mi2 drainage area) and Connecticut (9.187 mi2

drainage area). The Rhode Island towns in the subbasin include 

Coventry, Exeter, Hopkinton, Richmond, and West Greenwich 

(fig. 3). Connecticut towns include North Stonington, Sterling, 

and Voluntown. Land areas and land-use areas by category are 

summarized in tables 3 and 4. The Upper Wood River flows 

southeasterly from Connecticut into Rhode Island. The Upper 

Wood aquifer (fig. 4) is the source for some self-supplied water 

users and the Richmond Water Supply District. The subbasin is 

in Rhode Island (88 percent) and Connecticut (12 percent), and 

the surficial deposits are approximately 26 percent sand and 

gravel. There are two continuous stream-gaging stations in the 

subbasin (fig. 5), Wood River at Arcadia, RI (station 

01117800), and Wood River at Hope Valley, RI (station 

01118000), with more than 35 and 59 years of data, 

respectively. The surficial deposits in the area upstream of the 

Arcadia stream-gaging station are approximately 28 percent 

sand and gravel. The surficial deposits in the area upstream of 

the Hope Valley stream-gaging station are approximately 26 

percent sand and gravel. 

The Lower Wood subbasin (36.42 mi2 drainage area) is in 

the western section of the Pawcatuck Basin in Rhode Island 

(36.40 mi2 drainage area) and Connecticut (0.024 mi2 drainage 

area). The Rhode Island towns in the subbasin are Charlestown, 

Hopkinton, and Richmond, and the Connecticut towns in the 

subbasin are North Stonington and Voluntown (fig. 3). Land 

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

3 and 4. The stream-gaging station at Hope Valley defines the 

split between the Upper and Lower Wood subbasins (fig. 4). 

The Lower Wood River continues to flow south, but 

encompasses Meadow Brook from the east before the 

confluence with the Pawcatuck River in Alton, RI. The water 

withdrawals in the Lower Wood aquifer (fig. 4) are from selfsupplied entities. The surficial deposits in the subbasin are 48 

percent sand and gravel. The area draining to the Pawcatuck 

River at Wood River Junction (station 01117500) is 100 mi2; 

this station is the only continuous stream-gaging station in the 

subbasin (fig. 5). More than 60 years of surface-water data are 

available for the station. Approximately 47 percent of the 

drainage area at the stream-gaging station is sand and gravel 

deposits. 

The Lower Pawcatuck subbasin (97.45 mi2 drainage area) 

is in the southwestern section of the Pawcatuck Basin in Rhode 

Island (49.54 mi2 drainage area) and Connecticut (47.91 mi2

drainage area). The subbasin includes the towns of 

Charlestown, Hopkinton, and Westerly in Rhode Island, and 

North Stonington, Stonington, and Voluntown in Connecticut 

(fig. 3). Land areas and land-use areas by category are 

summarized in tables 3 and 4. The Green Fall River, Wyassup 

Brook, and Shunock River flow southeasterly into the 

Pawcatuck River, which flows southwesterly into Long Island 

Sound. The Ashaway, Shunock, Bradford, and Westerly 

aquifers (fig. 4) are the defined ground-water sources in the 

Lower Pawcatuck subbasin. The Lower Pawcatuck subbasin is 

approximately 32 percent sand and gravel deposits. The 

continuous stream-gaging station in the subbasin (fig. 5), 

Pawcatuck River at Westerly, RI (station 01118500), has more 

than 62 years of surface-water data. The surficial deposits are 

approximately 37 percent sand and gravel for the area upstream 

of the Westerly stream-gaging station.

Minor Civil Divisions

The U.S. Census Bureau classifies towns and cities into 

minor civil divisions (MCDs). The 14 MCDs in the study area 

include Charlestown, Coventry, East Greenwich, Exeter, 

Hopkinton, North Kingstown, Richmond, South Kingstown, 

West Greenwich, and Westerly in Rhode Island, and North 

Stonington, Sterling, Stonington, and Voluntown in 

Connecticut. The study area also includes part of the 

Narragansett Tribal Land in the southeastern section of 

Charlestown. The town of Narragansett is in the Narragansett 

Bay Drainage Basin, but is included in sections of this report to 

account for interbasin transfers. Polygons within the towns 

were assigned population densities in the GIS coverages by 

using Census Bureau TIGER data available through the Rhode 

Island Geographic Information System (RIGIS) and the 

Connecticut Map and Geographic Information Center 

(MAGIC). These 1990 population coverages were merged with 

the USGS basin and subbasin coverage to determine the 

population in the Pawcatuck Basin, and in the subbasins (table 

1). Also, the town land area by basin and subbasin was 

determined by overlaying town boundaries and basin-boundary 

coverages. The ratio of the 1990 to 1995 through 1999 

populations for towns by subbasins is the increase (or decrease) 

of the town population. To estimate the 1995 through 1999 

town populations on public- and self-water supplies and publicand self-wastewater disposals, the population ratio was 

multiplied by the 1990 population on private wells and the 1990 

population on public-wastewater collection (table 1) that were 

available through RIGIS and the Connecticut MAGIC. Publicwater 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. For this 

report, public suppliers were categorized into major public 

suppliers that have a system of distribution, and minor suppliers 

that have closed systems. 

The town of Charlestown is in south central Rhode Island 

(fig. 3). The total land area is 37.63 mi2, of which 25.1 mi2 is in 

the Pawcatuck Basin (table 7). The estimated total town 

population for the study period was 7,062, and the estimated 

town population in the basin for the study period was 4,218 

(table 7). Charlestown also includes the Narragansett Tribal 

Land, which comprises 1,400 acres in the southeastern section 

of the town (Narragansett Indian Tribe, 2002). Charlestown has 

no major public-water supply or wastewater-collection 

facilities, and only one minor water supplier that serves a small 

population. 
The Pawcatuck Basin 17

Table 7. Summary of total land area, land area in the Pawcatuck Basin, total 1990 populations, total estimated 1995–99 populations, 

estimated 1995–99 populations in the Pawcatuck Basin, and land-use area by category in the Pawcatuck Basin, southern Rhode Island 

and southeastern Connecticut.

[All towns are in Rhode Island unless otherwise noted. Total populations: Rhode Island 1990—From Rhode Island Geographic Information System (1991). 

Estimated 1995–99—From the Rhode Island Economic Development Corporation (2000); Connecticut 1990—From the University of Connecticut Center for 

Geographic Information and Analysis (2000). Estimated 1995–99—From the Connecticut Department of Health (1995, 1996, 1997, 1998, 1999). Land-use area 

by category: Rhode Island—Estimated by using the coverage from the Rhode Island Geographic Information System (1995a); Connecticut—Estimated from 

the Map and Geographic Information Center (1990a, 1990b, 1990c, 1990d). mi2, square mile; --, not applicable]

Towns

Total land 

area

(mi2)

Land area in

the Pawcatuck 

Basin

(mi2)

Total populations Estimated 

1995–99 

population in

the Pawcatuck 

Basin

Total land-use area by category (mi2)

1990 Estimated

1995–99

CommercialIndustrialAgricultural

Charlestown 37.63 25.53 6,381 7,062 4,218 0.302 0.066 1.439

Coventry 62.45 .873 31,081 32,523 67 .627 .355 2.392

East Greenwich 16.25 .095 11,807 12,120 38 .349 .195 .924

Exeter 58.39 53.41 5,472 5,932 5,413 .140 .042 4.451

Hopkinton 44.10 44.10 6,871 7,763 7,763 .162 .065 3.791

North Kingstown 43.42 3.374 23,774 25,906 873 .788 1.676 3.133

North Stonington, CT 54.94 38.29 4,884 4,892 3,617 .536 .536 5.105

Richmond 40.74 40.74 5,350 6,631 6,631 .172 .082 4.262

South Kingstown 60.85 27.98 24,632 26,401 10,682 .490 .155 7.666

Sterling, CT 27.31 5.819 2,357 2,755 444 -- -- 2.229

Stonington, CT 38.70 5.125 16,919 16,435 4,864 1.426 1.426 3.110

Voluntown, CT 39.78 7.886 2,113 2,252 410 .092 .092 1.778

West Greenwich 51.22 26.13 3,501 3,956 1,486 .227 .064 1.865

Westerly 29.51 22.91 21,603 22,896 20,022 .696 .114 1.584

The town of Coventry is in central Rhode Island (fig. 3). 

The total land area is 62.45 mi2, of which 0.873 mi2 is in the 

Pawcatuck Basin (table 7). The estimated total town population 

for the study period was 32,523, and the estimated town 

population in the basin for the study period was 67 (table 7). 

Although the Kent County Water Authority supplies water to a 

section of Coventry in the Pawtuxet Basin, the portion of the 

town in the Pawcatuck Basin is self-supplied. Likewise, the 

wastewater-collection area for the town of Coventry is outside 

of the Pawcatuck Basin. 

The town of East Greenwich is in central Rhode Island 

(fig. 3). The total land area is 16.25 mi2, of which 0.095 mi2 is 

in the Pawcatuck Basin (table 7). The estimated total town 

population for the study period was 12,120, and the estimated 

town population in the basin for the study period was 38 

(table 7). The Kent County Water Authority supplies water to 

all of East Greenwich, and the East Greenwich WastewaterTreatment Facility (WWTF) collects wastewater for the 

community.

The town of Exeter is in south central Rhode Island 

(fig. 3). The total land area is 58.39 mi2, of which 53.41 mi2 is 

in the Pawcatuck Basin (table 7). The estimated total town 

population for the study period was 5,932, and the estimated 

town population in the basin for the study period was 5,413 

(table 7). There are no major public water suppliers in Exeter. 

The Ladd School, however, a minor public-water supplier and 

wastewater-treatment facility, was in operation for 5 months 

(from January through May of 1995) during the study period. 

The facility is currently (2004) owned by the Rhode Island 

Economic Development Corporation (RIEDC) and is 

undeveloped. Three minor public-water suppliers serve 

small populations in the basin. 

The town of Hopkinton is in southwestern Rhode Island 

(fig. 3). The total land area is 44.10 mi2, all of which is located 

in the Pawcatuck Basin (table 7). The estimated population for 

the study period was 7,763 (tables 7). Hopkinton has no public 

water-supply system, although a small portion of the town is 

served by the Richmond Water Supply District, and four minor 

public-water suppliers serve small populations. Likewise, the 

town has no local wastewater collection. 

The town of Narragansett is in south central Rhode Island 

(fig. 3). The town is not located in the Pawcatuck Basin, but is 

included in this study to account for interbasin transfers. The 

estimated total population for the study period was 15,777. The 

Narragansett Water Department supplies the town through 

wholesale and retail water purchases from UWRI, which 

withdraws its water from the Pawcatuck Basin. Wastewater is 

collected from the town by the Narragansett WWTF, in the 

locality of Scarborough, and by the South Kingstown Regional 

WWTF. 
18 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

The town of North Kingstown is in central Rhode Island 

(fig. 3). The total land area is 43.42 mi2, of which 3.374 mi2 

is in the Pawcatuck Basin (table 7). The estimated total town 

population for the study period was 25,906, and the estimated 

town population in the basin for the study period was 873 

(table 7). The North Kingstown Water District serves 

approximately 94 percent of the town. There is no public 

wastewater collection in North Kingstown. A private 

wastewater-treatment facility serves the Quonset Point 

establishment, formerly a U.S. Navy Air Station, which is 

currently (2004) owned and operated by the RIEDC. 

The town of Richmond is in southwestern Rhode Island 

(fig. 3). The total land area is 40.74 mi2 and it is all within the 

Pawcatuck Basin (table 7). The estimated total town population 

for the study period was 6,631 (table 7). The Richmond Water 

Supply District serves populations of the town in the Upper 

Wood subbasin of the Pawcatuck Basin, and serves a small 

section of the town of Hopkinton. Richmond has no public 

wastewater collection. One minor water supplier serves a small 

population in the basin. 

The town of South Kingstown is in south-central Rhode 

Island (fig. 3). The total land area is 60.85 mi2, of which 

27.98 mi2 is in the Pawcatuck Basin (table 7). The estimated 

total town population for the study period was 26,401, and the 

estimated town population in the basin for the study period was 

10,682 (table 7). 

Four major water suppliers withdraw and serve the town 

of South Kingstown: URI, Kingston Water District, UWRI, 

and South Kingstown Water Department. Located in the 

northwestern portion of South Kingstown, all of URI at 

Kingston is in the Pawcatuck Basin, and supplies the residential 

community and campus facilities. Approximately 10,000 to 

13,000 people are supplied at URI from September to May, and 

3,000 to 7,000 are supplied from June through August. The 

Kingston Water District supplies the rest of the locality in 

the Pawcatuck Basin, as well as areas outside of the basin. 

Northeastern sections of South Kingstown (Wakefield and 

Peace Dale) are also supplied by a private water utility, UWRI, 

which withdraws water from the Pawcatuck Basin. In addition, 

UWRI distributes retail water to the town and sells water 

wholesale to the South Kingstown Water Department and to the 

Narragansett Water Department. The total average population 

of the towns served by UWRI during the study period was 

18,000. Along the coast, in the southern part of the town, the 

South Kingstown Water Department withdraws and distributes 

water outside of the Pawcatuck Basin. These withdrawals are 

not included in the remainder of this report; however, the 

Narragansett Water Department purchases from UWRI are 

included as exports from the Pawcatuck Basin. The South 

Kingstown Regional WWTF serves the town and some sections 

of Narragansett. Wastewater collected within the Kingston 

Water District and the URI service area is exported to the South 

Kingstown Regional WWTF located outside of the study area. 

One minor water supplier serves a small population in the basin. 

The town of West Greenwich is in central Rhode Island 

(fig. 3). The total land area is 51.22 mi2, of which 26.13 mi2 

is in the Pawcatuck Basin (table 7). The estimated total town 

population for the study period was 3,956, and the estimated 

town population in the basin for the study period was 1,486 

(table 7). The Kent County Water Authority serves part of the 

town of West Greenwich that is not in the basin; therefore, the 

Kent County Water Authority service area is not included in this 

report. Likewise, a small area outside of the basin is served by 

the West Warwick Regional WWTF. One minor water supplier 

serves a small population in the basin.

The town of Westerly is in southwestern Rhode Island 

(fig. 3). The total land area is 29.51 mi2, of which 22.91 mi2

is in the Pawcatuck Basin (table 7). The estimated total town 

population for the study period was 22,896, and the estimated 

town population in the basin for the study period was 20,022 for 

the study period (table 7). The Westerly Water Department 

serves the town and the village of Pawcatuck in Stonington, CT. 

The Westerly wastewater facility serves only the town. 

The town of North Stonington is in southeastern 

Connecticut (fig. 3). The total land area is 54.94 mi2, of which 

38.29 mi2 is in the Pawcatuck Basin (table 7). The estimated 

total town population for the study period was 4,892, and the 

estimated town population in the basin for the study period was 

3,617 (table 7). There are no major water-supply or wastewatercollection systems in the portion of the town in the basin.
Water Use 19

The town of Sterling is in eastern Connecticut (fig. 3). 

The total land area is 27.31 mi2, of which 5.819 mi2 is in the 

Pawcatuck Basin (table 7). The estimated total town population 

for the study period was 2,755, and the estimated town 

population in the basin for the study period was 444 (table 7). 

There are no major water-supply or wastewater-collection 

systems in the part of the town in the basin.

The town of Stonington is in southeastern Connecticut 

(fig. 3). The total land area is 38.70 mi2, of which 5.125 mi2

is in the Pawcatuck Basin (table 7). The estimated total town 

population for the study period was 16,435, and the estimated 

town population in the basin for the study period was 4,864 

(table 7). The Stonington village of Pawcatuck is in the basin. 

As previously mentioned, the town of Westerly Water 

Department serves the village of Pawcatuck. The Southern 

Connecticut Water Authority also supplies water to Stonington 

in areas outside of the basin. The Stonington Water Pollution 

Control Authority has three collection and treatment facilities 

in the town: Stonington-Borough, Stonington-Mystic, and 

Stonington-Pawcatuck. The Stonington-Pawcatuck facility is 

the only facility in the town whose service area and discharge is 

in the Pawcatuck Basin.

The town of Voluntown is in eastern Connecticut (fig. 3). 

The total land area is 39.78 mi2, of which 7.886 mi2 is in the 

Pawcatuck Basin (table 7). The estimated total town population 

for the study period was 2,252, and the estimated town 

population in the basin for the study period was 410 (table 7). 

There are no major public water supplies or WWTFs in 

Voluntown. The majority of the town land area, 70 percent, 

is the Pachaug State Forest. 

Water Use

Water-use data for the Pawcatuck Basin and subbasins 

were organized by using the New England Water-Use Data 

System (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. 2). During 

the study period, data were categorized as either self- or publicsupplied withdrawals from ground water. Conveyance losses 

are an example of non-account water use (which is unmetered) 

in public-supply systems, and include leaks, system flushing, 

and fire-hydrant uses within the systems. The non-account 

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- and self-supplied users. The public-water supply and 

self-supplied domestic, industrial, and commercial withdrawals 

were from ground water. Consumptive water use is 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 

surface-water body. Return flow to ground water or surface 

water includes site-specific discharges, permitted dischargers, 

and aggregate dischargers, which are self-disposed within the 

town, basin, and subbasins. Water withdrawals, water use, 

consumptive use, and return flow were calculated for each 

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

New England Water-Use Data System

The data entered into NEWUDS consist of site-specific 

and aggregate water withdrawals, uses, and discharges in the 

Pawcatuck Basin and its subbasins. When available, monthly, 

quarterly, and yearly metered (or reported) data were entered 

from original source and converted to common units (Mgal/d) 

for comparison of the data. Unmetered water withdrawals, uses, 

and discharges were calculated by methods used to estimate 

water use by category (domestic, industrial, commercial, and 

agricultural). The database was used as a tool to track the water 

withdrawn from the Pawcatuck Basin and subbasins. The 

database was queried to obtain the average water use for the 

study period, and the results are in the tables of this report. For 

quality-assurance purposes, NEWUDS allows the data 

compiler to indicate the original data source, rate units, and 

method of rate determined within the database. Documentation 

describing database development and how to use the database 

are presented in the reports by Tessler (2002) and Horn (2003), 

respectively.
20 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Public-Water Supply and Interbasin Transfers

Public-water suppliers are defined as suppliers serving 

more than 25 people or having 15 service connections yearround. For this report, public suppliers were categorized 

into major public suppliers (table 8) that have a system of 

distribution, and minor suppliers that have closed systems. 

Five major public-water suppliers serve the Pawcatuck Basin: 

Kingston Water District, UWRI, URI, Richmond Water Supply 

District, and the Westerly Water Department, which supply the 

domestic, commercial, industrial, and agricultural sectors. 

Thirteen minor water suppliers serve small public populations, 

such as nursing homes, condominium associations, and mobile 

home parks (table 9). All estimated public-water supply 

withdrawals, and self-supplied withdrawals, by town and 

subbasin, are listed in table 10. The total water withdrawals, 

use, and return flow from public and self supplies by town and 

subbasin are summarized in figures 6, 7, and 8.

The Kingston Water District supplies the domestic, 

industrial, commercial, and agricultural water users in the 

locality of Kingston. The average withdrawals for the study 

period were 0.444 Mgal/d from the Chipuxet aquifer 

in the Chipuxet subbasin, water use in the subbasin was 

approximately 0.362 Mgal/d, and the interbasin transfers 

(export) to the South Coastal Drainage Basin and West 

Narragansett Bay Drainage Basin were approximately 

0.082 Mgal/d. The Kingston Water District accounts for 10 

percent of the total withdrawals in the Chipuxet subbasin and 

4 percent of the total withdrawals in the Pawcatuck Basin. 

The water withdrawals and distributions are summarized in 

figure 9 and table 8.

The UWRI system includes the Tuckertown (four 

wells) and Howland (two wells) well fields that are in the 

Chipuxet subbasin. This supply system withdrew an average 

of 2.603 Mgal/d during the study period from the Mink aquifer. 

UWRI withdrew 62 percent of the total withdrawals in the 

Chipuxet subbasin and 23 percent of the total withdrawals in the 

basin. The withdrawals and distributions are summarized in 

figures 7 and 10 and table 8 for the UWRI system.

URI supplies the student residents and other school uses 

from the Chipuxet subbasin. During the study period, URI 

withdrew approximately 0.440 Mgal/d from the Chipuxet 

aquifer. URI withdrew 10 percent of the total withdrawals in the 

Chipuxet subbasin and 4 percent of the total withdrawals in the 

Pawcatuck Basin. The withdrawals, use, and exports are 

summarized in figure 11 and table 8 for the URI water supply. 

The major water supplier that withdrew the least amount of 

water in the basin was the Richmond Water Supply. Richmond 

Water Supply withdrew an average of 0.045 Mgal/d during the 

study period from the Upper Wood aquifer in the Upper Wood 

subbasin. The Richmond Water Supply withdrew 6 percent of 

the total withdrawals in the Upper Wood subbasin and 0.4 

percent of the total withdrawals in the basin. The withdrawals 

and uses are summarized in figure 12 and table 8 for the watersupply system. 

The largest major water supplier in the Pawcatuck Basin 

is the Westerly Water Department, in the Lower Pawcatuck 

subbasin. This supplier withdrew an average of 3.236 Mgal/d 

during the study period. The Westerly Water Department 

withdrew 75 percent of the total withdrawals in the Lower 

Pawcatuck subbasin and 29 percent of the total withdrawals in 

the Pawcatuck Basin. The water withdrawals and use are 

summarized in figure 13 and table 8 for the Westerly Water 

Department. 

Thirteen minor water suppliers serve the Pawcatuck Basin 

(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, and 70 gal/d/person in Connecticut) determined by 

Korzendorfer and Horn (1995). The total estimated water 

withdrawals in the basin for minor suppliers was 0.099 Mgal/d. 

Estimated water withdrawals for the subbasins ranged from 

0.005 Mgal/d (Beaver–Pasquiset subbasin) to 0.025 Mgal/d 

(Lower Wood subbasin). Estimated water withdrawals for 

the individual minor suppliers ranged from 0.004 Mgal/d to 

0.013 Mgal/d. 

Three systems transfer public-supply water out of the 

Pawcatuck Basin. The Kingston Water District exports about 

0.082 Mgal/d to the South Coastal and West Narragansett Bay 

Drainage Basins from the Chipuxet subbasin in the Pawcatuck 

Basin. The UWRI system distributes water within the South 

Coastal Drainage Basin, the West Narragansett Bay Drainage 

Basin, and the Pawcatuck Basin. Wholesale distributions from 

the UWRI system are exported to the South Kingstown and 

Narragansett Water Departments, whose service areas are in the 

South Coastal Drainage Basin and West Narragansett Bay 

Drainage Basin. The 1995 through 1999 average amount of 

wholesale water purchased by South Kingstown from UWRI 

was 0.040 Mgal/d. The 1995 through 1999 average amount of 

wholesale water purchased by the Narragansett Water 

Department from UWRI was 0.633 Mgal/d. The total exports 

from these two wholesale purchases was 0.673 Mgal/d from the 

Chipuxet subbasin of the Pawcatuck Basin. Parts of the 

Westerly Water Department retail service area are in the South 

Coastal Drainage Basin, and approximately 0.288 Mgal/d were 

exported out of the Lower Pawcatuck subbasin of the 

Pawcatuck Basin. 
Water Use 21

Table 8. Major public-water suppliers by subbasins in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut.[Usquepaug–Queen, Beaver–Pasquiset, and Lower Wood subbasins have no major public-water suppliers. Reference letter: Identifer used in figure 4. All towns/cities assumed to be in Rhode Island unless 

otherwise noted. Aquifer type: SG, sand and gravel. Mgal/d, million gallons per day; --, not applicable]

 Major public-water supplier Reference letter Town (locality) Well field and well description (Mgal/d) Aquifer Water withdrawals 1995–99 (Mgal/d) Type Name

Chipuxet Subbasin

Kingston Water Department A South Kingstown (Kingston) Well 1 SG Chipuxet 0.137

B South Kingstown (Kingston) Well 2 SG Chipuxet .307

Total ........................................................................................................................................................................................................................................................ 0.444

United Water of Rhode Island C South Kingstown (Wakefield) Tuckertown well field: well 1 SG Mink .012

D South Kingstown (Wakefield) Tuckertown well field: well 2 SG Mink .297E South Kingstown (Wakefield) Tuckertown well field: well 3 SG Mink .010F South Kingstown (Wakefield) Tuckertown well field: well 4 SG Mink .398G South Kingstown (Wakefield) Howland well field: well 5 SG Mink .839H South Kingstown (Wakefield) Howland well field: well 6 SG Mink 1.047

Total ........................................................................................................................................................................................................................................................ 2.603

University of Rhode Island I, J, K South Kingstown (Kingston) Well field: well 2, well 3, and well 4 SG Chipuxet .440

Subbasin Total......................................................................................................................................................................................................................................... 3.487

Upper Wood Subbasin

Richmond Water Supply L Richmond Well 1 SG Upper Wood 0.045

Well 2 (backup only) SG Upper Wood --

Subbasin total.......................................................................................................................................................................................................................................... 0.045

Lower Pawcatuck Subbasin

Westerly Water Department M, N, O Westerly Well field 1: well 1A, well 1B, well 1C SG Westerly 0.845

P, Q, R Westerly Well field 2: well 2A, well 2B, well 2C SG Westerly 1.081S Westerly Well 3 SG Westerly .432T Westerly Bradford Well II SG Bradford .270U Westerly Bradford Well III SG Bradford .281V Westerly Crandall well SG Bradford .327W Stonington, CT (Pawcatuck) Noyes Avenue well (backup only) SG Westerly --

Subbasin total.......................................................................................................................................................................................................................................... 3.236

Pawcatuck Basin

Basin total................................................................................................................................................................................................................................................ 6.768
22 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

1Ladd School facility did not withdraw after May 1995.

Table 9. Minor public-water suppliers by subbasins in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut.

[Coefficient used for minor-supplier population is 67 gal/d/person. BD, bedrock well; DG, dug well; SG, sand and gravel well; gal/d/person, gallons per day per 

person; Mgal/d, million gallons per day]

Minor public-water supplier Town Type of well(s)

Estimated 1995–99

Population

Water withdrawals

and use

(Mgal/d)

Chipuxet Subbasin

Allen Health Center South Kingstown SG and BD 175 0.012

Split Rock Exeter BD and DG 140 .009

Usquepaug–Queen Subbasin

Hillesdale Mobile Home Park Richmond BD 200 0.013

Ladd School1 Exeter SG 60 .004

Shady Acres Rest Home Exeter BD 77 .005

Beaver–Pasquiset Subbasin

Shannock Water Association Richmond BD 75 0.005

Upper Wood Subbasin

Camp E-Hun-Tee West Greenwich BD 65 0.004

Mobile Village Park Exeter BD 150 .010

Lower Wood Subbasin

Canonchet Cliffs I Hopkinton BD 63 0.004

Canonchet Cliffs II Hopkinton BD 59 .004

Indian Cedar Mobile Home Park Charlestown BD 140 .009

Lindhbrook Greene Condo Hopkinton SG 120 .008

Lower Pawcatuck Subbasin

Bethal Village Water Association Hopkinton BD 180 0.012

Pawcatuck Basin

Total................................................................................................................................................... 1,504 0.099
Water Use 23

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

CHIPUXET

RIVER

SUBBASIN

 USQUEPAUGQUEEN RIVER

SUBBASIN

BEAVERPASQUISET

RIVER

SUBBASIN

UPPER WOOD

RIVER

SUBBASIN

 LOWER WOOD

RIVER

SUBBASIN

 LOWER

PAWCATUCK

RIVER

SUBBASIN

SUBBASINS OF THE PAWCATUCK BASIN

WATER WITHDRAWALS,

 IN MILLION GALLONS PER DAY

Public-Supply Withdrawals

Self-Supplied Domestic

Self-Supplied Commercial

Self-Supplied Industrial

Self-Supplied Agricultural

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

subbasins in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99. 
24 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Table 10. Ground-water and surface-water withdrawals by town and subbasin in the Pawcatuck Basin, southern Rhode Island and 

southeastern Connecticut, 1995–99.

[Public-supply, domestic, commercial, and industrial water withdrawals are from ground water (wells). For agriculture, irrigation-water withdrawals 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 on public supply. All towns 

are in Rhode Island unless otherwise noted. Mgal/d, million gallons per day; <0.001, values not included in town and subbasin totals; <, actual value is less than 

value shown; --, not applicable]

Towns

Public-supply

withdrawals

(Mgal/d)

Self-supply withdrawals (Mgal/d) Total

Domestic (Mgal/d) Commercial Industrial Agricultural

Chipuxet Subbasin

Charlestown -- 0.016 -- -- 0.002 0.018

Exeter 0.009 .056 0.003 0.011 .033 .112

North Kingstown -- .009 <.001 .002 .041 .052

Richmond -- .022 .001 -- .027 .050

South Kingstown 3.496 .213 .065 .102 .104 3.980

Subbasin total 3.505 0.316 0.069 0.115 0.207 4.212

Usquepaug–Queen Subbasin

East Greenwich -- 0.001 -- -- <0.001 0.001

Exeter 0.009 .209 0.006 0.002 .190 .416

North Kingstown -- .001 .004 -- .005 .010

Richmond .013 .052 .001 -- .014 .080

South Kingstown -- .032 .002 -- .098 .132

West Greenwich -- .017 -- .017 .001 .035

Subbasin total 0.022 0.312 0.013 0.019 0.308 0.674

Beaver–Pasquiset Subbasin

Charlestown -- 0.099 0.003 0.002 0.019 0.123

Exeter -- .020 .005 -- .004 .029

Richmond 0.005 .153 .001 .027 .124 .310

South Kingstown -- .001 -- -- -- .001

Subbasin total 0.005 0.273 0.009 0.029 0.147 0.463

Upper Wood Subbasin

Coventry -- 0.005 -- -- <0.001 0.005

Exeter 0.010 .071 0.002 0.011 .023 .117

Hopkinton -- .145 <.001 .016 .036 .197

North Stonington, CT -- -- -- -- -- --

Richmond .045 .072 .011 .067 .081 .276

Sterling, CT -- .030 -- -- .003 .033

Voluntown, CT -- .013 -- <.001 .001 .014

West Greewich .004 .084 <.001 .038 .011 .137

Subbasin total 0.059 0.420 0.013 0.132 0.155 0.779

Lower Wood Subbasin

Charlestown 0.009 0.093 <0.001 0.002 0.015 0.119

Hopkinton .016 .101 <.001 .008 .182 .307

North Stonington, CT -- -- -- -- -- --

Richmond -- .136 .005 .047 .205 .393

Voluntown, CT -- -- -- <.001 <.001 <.001

Subbasin total 0.025 0.330 0.005 0.057 0.402 0.819
Water Use 25

Lower Pawcatuck Subbasin

Charlestown -- 0.068 <0.001 -- 0.004 0.072

Hopkinton 0.012 .255 .001 0.024 .071 .363

North Stonington, CT -- .206 -- .013 .015 .234

Stonington, CT -- .029 -- .001 .003 .033

Voluntown, CT -- .015 -- <.001 .003 .018

Westerly 3.236 .046 .109 .139 .053 3.583

Subbasin total 3.248 0.619 0.110 0.177 0.149 4.303

Pawcatuck Basin

Basin total 6.864 2.270 0.219 0.529 1.368 11.25

Table 10. Ground-water and surface-water withdrawals by town and subbasin in the Pawcatuck Basin, southern Rhode Island and 

southeastern Connecticut, 1995–99.—Continued

[Public-supply, domestic, commercial, and industrial water withdrawals are from ground water (wells). For agriculture, irrigation-water withdrawals 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 on public supply. All towns 

are in Rhode Island unless otherwise noted. Mgal/d, million gallons per day; <0.001, values not included in town and subbasin totals; <, actual value is less than 

value shown; --, not applicable]

Towns

Public-supply

withdrawals

(Mgal/d)

Self-supply withdrawals (Mgal/d) Total

Domestic Commercial Industrial Agricultural (Mgal/d)

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

CHIPUXET

RIVER

SUBBASIN

 USQUEPAUGQUEEN RIVER

SUBBASIN

BEAVERPASQUISET

RIVER

SUBBASIN

UPPER WOOD

RIVER

SUBBASIN

 LOWER WOOD

RIVER

SUBBASIN

 LOWER

PAWCATUCK

RIVER

SUBBASIN

SUBBASINS OF THE PAWCATUCK RIVER BASIN

WATER USE, 

IN MILLION GALLONS PER DAY 

Public-Supply Domestic

Self-Supplied Domestic

Public-Supply Commercial

Self-Supplied Commercial

Public-Supply Industrial

Self-Supplied Industrial

Public-Supply Agricultural

Self-Supplied Agricultural

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

the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99. 
26 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

CHIPUXET

RIVER

SUBBASIN

 USQUEPAUGQUEEN RIVER

SUBBASIN

BEAVERPASQUISET

RIVER

SUBBASIN

UPPER WOOD

RIVER

SUBBASIN

 LOWER

WOOD RIVER

SUBBASIN

 LOWER

PAWCATUCK

RIVER

SUBBASIN

SUBBASINS OF THE PAWCATUCK RIVER SUBBASIN

WATER RETURN FLOW,

IN MILLION GALLONS PER DAY

Self-Disposed Domestic

Self-Disposed Commercial

Self-Disposed Industrial

Rhode Island Pollutant Discharge Elimination System

Wastewater-Treatment Facilities

Figure 8. Wastewater-treatment facilities, Rhode Island Pollutant Discharge Elimination System, and self-disposed 

domestic, commercial, and industrial water return flow for the subbasins in the Pawcatuck Basin, southern Rhode Island 

and southeastern Connecticut, 1995–99. 
Water Use 27

KINGSTON WATER

DISTRICT WITHDRAWALS

WELL 1 -- 0.137 Mgal/d

WELL 2 -- 0.307 Mgal/d

KINGSTON DISTRIBUTION

0.444 Mgal/d

EXPORT TO COASTAL AND

NARRAGANSETT BAY

DRAINAGE BASINS

0.082 Mgal/d

ESTIMATED AGRICULTURAL

WATER USE

0.092 Mgal/d

ESTIMATED COMMERCIAL

WATER USE

0.009 Mgal/d

NON-ACCOUNT 

WATER USE

0.018 Mgal/d

ESTIMATED DOMESTIC

WATER USE

0.235 Mgal/d

ESTIMATED INDUSTRIAL

WATER USE

0.008 Mgal/d

Pawcatuck Basin

EXPLANATION

Basin Export

Mgal/d Million Gallons Per Day

Figure 9. Kingston Water District withdrawals, distribution, and estimated water uses in the Pawcatuck Basin and basin exports, 

southern Rhode Island, 1995–99.
28 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99 Well 1 - 0.012 Mgal/d Well 2 - 0.297 Mgal/d Well 3 - 0.010 Mgal/d Well 4 - 0.398 Mgal/d Well 5 - 0.839 Mgal/d Well 6 - 1.047 Mgal/d 0.717 Mgal/d HOWLAND TREATMENT 1.902 Mgal/d NON-ACCOUNT WATER USE RETAIL DISTRIBUTION 1.745 Mgal/d DOMESTIC DISTRIBUTIONS COMMERCIAL DISTRIBUTIONS 0.491 Mgal/d 1.056 Mgal/d INDUSTRIAL DISTRIBUTION 0.053 Mgal/d 0.674 Mgal/d GOVERNMENT DISTRIBUTION 0.145 Mgal/d 0.199 Mgal/d SOUTH KINGSTOWN DISTRIBUTION 0.040 Mgal/d NARRAGANSETT DISTRIBUTION 0.633 Mgal/d Pawcatuck Basin Basin Import/Export NON-ACCOUNT 0.001 Mgal/d 0.016 Mgal/d 2.618 Mgal/d TUCKERTOWN WELL FIELD WATER USE WHOLESALE DISTRIBUTION TUCKERTOWN TREATMENT NON-ACCOUNT WATER USE UNITED WATER OF RHODE ISLAND DISTRIBUTION HOWLAND WELL FIELD EXPLANATION Mgal/d Million Gallons Per Day Figure 10. United Water of Rhode Island withdrawals, treatment, distributions, non-account water use in the Pawcatuck Basin and basin exports, southern Rhode Island, 1995–99. 
Water Use 29

UNIVERSITY OF RHODE

ISLAND WITHDRAWAL

WELLS

0.440 Mgal/d

UNIVERSITY OF RHODE

ISLAND WATER USE

0.440 Mgal/d

Pawcatuck Basin

Basin Export

CONSUMPTIVE

WATER USE

0.044 Mgal/d

ESTIMATED

RETURN FLOW

0.396 Mgal/d

EXPLANATION

Mgal/d Million Gallons Per Day

Figure 11. University of Rhode Island withdrawals, water uses, and estimated exported return flow in the 

Pawcatuck Basin, southern Rhode Island, 1995–99. 

Domestic Water Use

Domestic water use is the amount of water used by 

residential populations either served by public water supplies or 

self-supplied users on private wells. The domestic water-use 

category includes the public-water-supply deliveries to users 

within the political or hydrologic boundaries in the study area. 

Domestic withdrawals were estimated from the census 

coverages available through RIGIS and Connecticut MAGIC. 

The coverage has the 1990 populations that are self-supplied. 

The coverages then were separated by subbasin. To obtain the 

populations on public-water supplies, the self-supplied 

populations were subtracted from the total population in the 

subbasins. 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-supplied 

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

domestic water use, which were based on the 1990 National 

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

Public-Supply Use

Because the water suppliers provide information on 

populations served within towns rather than subbasins, a 

Geographic Information System (GIS) was used to estimate 

subbasin populations on public supply by merging the 1990 

census blocks that have the domestic populations on private 

wells with the subbasin coverage. The 1990 population that 

supplies its own water was subtracted from the total population 

for each subbasin. The ratio of the 1990 to 1995 through 1999 

populations was applied in each subbasin to obtain the 

populations on public-supply and self-supplied water by 

subbasin for each town (table 1). Because limited withdrawal 

data are available for the 13 minor public suppliers in the basin, 

the water-use coefficient was applied to populations served for 

each entity (Korzendorfer and Horn, 1995). 

Public-supply water use in the subbasins ranged from 

0.024 Mgal/d (Beaver–Pasquiset subbasin) to 1.809 Mgal/d 

(Lower Pawcatuck subbasin) for domestic users. The estimated 

domestic uses of publicly supplied water by town are listed in 

table 11 and illustrated in figure 7. 

Self-Supplied Use

Domestic use of self-supplied water was calculated by 

merging the basin coverages with the U.S. Census 1990 

population coverages obtained through RIGIS and Connecticut 

MAGIC. The 1990 census blocks have the population using 

private wells. The 1995 through 1999 population using selfsupplied water for each subbasin was estimated from the 1990 

population and 1995 through 1999 ratio of growth within each 

subbasin (table 1). Domestic-water withdrawals and use in the 

subbasins ranged from 0.273 Mgal/d (Beaver–Pasquiset 

subbasin) to 0.619 Mgal/d (Lower Pawcatuck subbasin) for 

self-supplied users (figs. 6 and 7, tables 10 and 11). 
30 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

.

Table 11. Estimated water use by town and subbasin in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 

1995–99.

[All towns are in Rhode Island unless otherwise noted. Mgal/d, million gallons per day; <0.001, values not included in town and subbasin totals; <, actual value is 

less than value shown; --, not applicable]

Town

Domestic supply

(Mgal/d)

Commercial supply

(Mgal/d)

Industrial supply

(Mgal/d)

Agricultural supply

(Mgal/d) Total

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

Chipuxet Subbasin

Charlestown 0.002 0.016 -- -- -- -- -- 0.002 0.020

Exeter .006 .056 -- 0.003 -- 0.011 -- .033 .109

North Kingstown .040 .009 -- <.001 -- .002 -- .041 .092

Richmond .001 .022 -- .001 -- -- -- .027 .051

South Kingstown .482 .213 0.023 .065 0.053 .102 0.092 .104 1.134

Subbasin total 0.531 0.316 0.023 0.069 0.053 0.115 0.092 0.207 1.406

Usquepaug–Queen Subbasin

East Greenwich 0.002 0.001 -- -- -- -- -- <0.001 0.003

Exeter .011 .209 -- 0.006 -- 0.002 -- .190 .418

North Kingstown .009 .001 -- .004 -- -- -- .005 .019

Richmond .005 .052 -- .001 -- -- -- .014 .072

South Kingstown .001 .032 -- .002 -- -- -- .098 .133

West Greenwich -- .017 -- -- -- .017 -- .001 .035

Subbasin total 0.028 0.312 -- 0.013 -- 0.019 -- 0.308 0.680

Beaver–Pasquiset Subbasin

Charlestown 0.011 0.099 -- 0.003 -- 0.002 -- 0.019 0.134

Exeter -- .020 -- .005 -- -- -- .004 .029

Richmond .012 .153 -- .001 -- .027 -- .124 .317

South Kingstown .001 .001 -- -- -- -- -- -- .002

Subbasin total 0.024 0.273 -- 0.009 -- 0.029 -- 0.147 0.482

Upper Wood Subbasin

Coventry <0.001 0.005 -- -- -- -- -- <0.001 0.005

Exeter .009 .071 -- 0.002 -- 0.011 -- .023 .116

Hopkinton .010 .145 0.001 <.001 -- .016 -- .036 .208

North Stonington, CT -- -- -- -- -- -- -- -- --

Richmond .009 .072 .027 .011 0.001 .067 -- .081 .268

Sterling, CT .003 .030 -- -- -- -- -- .003 .036

Voluntown, CT .002 .013 -- -- -- <.001 -- .001 .016

West Greewich .004 .084 -- <.001 -- .038 -- .011 .137

Subbasin total 0.037 0.420 0.028 0.013 0.001 0.132 -- 0.155 0.786
Water Use 31

Lower Wood Subbasin

Charlestown 0.003 0.093 -- <0.001 -- 0.002 -- 0.015 0.113

Hopkinton .016 .101 -- <.001 -- .008 -- .182 .307

North Stonington, CT -- -- -- -- -- -- -- -- --

Richmond .008 .136 -- .005 -- .047 -- .205 .401

Voluntown, CT -- -- -- -- -- <.001 -- <.001 <.001

Subbasin total 0.027 0.330 -- 0.005 -- 0.057 -- 0.402 0.821

Lower Pawcatuck Subbasin

Charlestown 0.006 0.068 -- <0.001 -- -- -- 0.004 0.078

Hopkinton .023 .255 -- .001 -- 0.024 -- .071 .374

North Stonington, CT .059 .206 -- -- -- .013 -- .015 .293

Stonington, CT .323 .029 -- -- -- .001 -- .003 .356

Voluntown, CT <.001 .015 -- -- -- <.001 -- .003 .018

Westerly 1.398 .046 0.323 0.109 0.039 .139 -- .053 2.107

Subbasin total 1.809 0.619 0.323 0.110 0.039 0.177 -- 0.149 3.226

Pawcatuck Basin

Basin total 2.456 2.270 0.374 0.219 0.093 0.529 0.092 1.368 7.401

Table 11. Estimated water use by town and subbasin in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 

1995–99.—Continued

[All towns are in Rhode Island unless otherwise noted. Mgal/d, million gallons per day; <0.001, values not included in town and subbasin totals; <, actual value is 

less than value shown; --, not applicable]

Town

Domestic supply

(Mgal/d)

Commercial supply

(Mgal/d)

Industrial supply

(Mgal/d)

Agricultural supply

(Mgal/d) Total

(Mgal/d) Public Self Public Self Public Self Public Self
32 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

RICHMOND

WATER SUPPLY 

WELL 1 -- 0.045 Mgal/d

WELL 2 -- Backup only 

(not active during the 

study period)

ESTIMATED DOMESTIC

WATER USE

0.009 Mgal/d

ESTIMATED INDUSTRIAL

WATER USE

0.001 Mgal/d

ESTIMATED COMMERCIAL

WATER USE

0.027 Mgal/d

ESTIMATED COMMERCIAL

WATER USE

0.001 Mgal/d

ESTIMATED DOMESTIC

WATER USE

0.005 Mgal/d

Pawcatuck Basin

Basin Export

ESTIMATED DISTRIBUTION

TO RICHMOND

0.037 Mgal/d

ESTIMATED DISTRIBUTION

TO HOPKINTON

0.006 Mgal/d

NON-ACCOUNT

WATER USE

0.001 Mgal/d

EXPLANATION

Mgal/d Million Gallons Per Day

Figure 12. Richmond Water Supply withdrawals, estimated distributions, and estimated water uses in the Pawcatuck Basin, 

southern Rhode Island, 1995–99. 

Commercial and Industrial Water Use

Limited data are available on commercial and industrial 

water use from public-water supply and self-supplied systems, 

because withdrawals and use for these water-use categories 

(figs. 6 and 7) are not regulated in Rhode Island. Commercial 

and industrial water-use estimates, therefore, were derived from 

the total water calculated and divided by basin and subbasin for 

each town based on the land-use type. Commercial and 

industrial consumptive water use (table 12) is assumed to be 10 

percent of the total water use (Solley and others, 1998).
Water Use 33

Table 12. Consumptive water use by town and subbasin in the Pawcatuck Basin, southern Rhode Island and southeastern 

Connecticut, 1995–99.

[All towns are in Rhode Island unless otherwise noted. Mgal/d, million gallons per day; <0.001, values not included in town and subbasin totals; <, actual value is 

less than value shown; --, not applicable] 

Town/City Domestic (Mgal/d) Commercial (Mgal/d) Industrial

(Mgal/d) Agricultural (Mgal/d) Total 

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

Chipuxet Subbasin

Charlestown <0.001 0.003 -- -- -- -- -- 0.002 0.005

Exeter .001 .009 -- <0.001 -- 0.001 -- .033 .044

North Kingstown <.001 .008 -- <.001 -- <.001 -- .041 .049

Richmond -- .004 -- <.001 -- -- -- .027 .031

South Kingstown .060 .045 0.002 .006 0.005 .010 0.092 .104 .324

Subbasin total 0.061 0.069 0.002 0.006 0.005 0.011 0.092 0.207 0.453

Usquepaug–Queen Subbasin

East Greenwich <0.001 <.0001 -- -- -- -- -- <0.001 <0.001

Exeter .001 .032 -- 0.001 -- <0.001 -- .190 .224

North Kingstown <.001 .001 -- <.001 -- -- -- .005 .006

Richmond -- .009 -- <.001 -- -- -- .014 .023

South Kingstown -- .005 -- <.001 -- -- -- .098 .103

West Greenwich -- .003 -- -- -- .002 -- .001 .006

Subbasin total 0.001 0.050 -- 0.001 -- 0.002 -- 0.308 0.362

Beaver–Pasquiset Subbasin

Charlestown 0.001 0.015 -- <0.001 -- <0.001 -- 0.019 0.035

Exeter -- .003 -- .001 -- -- -- .004 .008

Richmond -- .025 -- <.001 -- .003 -- .124 .152

South Kingstown <.001 <.001 -- -- -- -- -- -- <.001

Subbasin total 0.001 0.043 -- 0.001 -- 0.003 -- 0.147 0.195

Upper Wood Subbasin

Coventry -- 0.001 -- -- -- -- -- <0.001 0.001

Exeter <0.001 .012 -- <0.001 -- 0.001 -- .023 .036

Hopkinton .001 .022 <0.001 <.001 -- .002 -- .036 .061

North Stonington, CT -- -- -- -- -- -- -- -- --

Richmond -- .012 .003 .001 <0.001 .007 -- .081 .104

Sterling, CT .001 .004 -- -- -- -- -- .003 .008

Voluntown, CT <.001 .002 -- -- -- <.001 -- .001 .003

West Greenwich <.001 .013 -- <.001 -- .004 -- .011 .028

Subbasin total 0.002 0.066 0.003 0.001 <0.001 0.014 -- 0.155 0.241

Lower Wood Subbasin

Charlestown <0.001 0.014 -- <0.001 -- <0.001 -- 0.015 0.029

Hopkinton .001 .016 -- <.001 -- .001 -- .182 .200

North Stonington, CT -- -- -- -- -- -- -- -- --

Richmond -- .022 -- .001 -- .005 -- .205 .233

Voluntown, CT -- -- -- -- -- <.001 -- <.001 <.001

Subbasin total 0.001 0.052 -- 0.001 -- 0.006 -- 0.402 0.462
34 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Lower Pawcatuck Subbasin

Charlestown <0.001 0.011 -- <0.001 -- -- -- 0.004 0.015

Hopkinton .001 .040 -- <.001 -- 0.002 -- .071 .114

North Stonington, CT .001 .040 -- -- -- .001 -- .015 .057

Stonington, CT .034 .019 -- -- -- <.001 -- .003 .056

Voluntown, CT -- .002 -- -- -- <.001 -- .003 .005

Westerly .129 .076 0.032 .011 0.004 .014 -- .053 .319

Subbasin total 0.165 0.188 0.032 0.011 0.004 0.017 -- 0.149 0.566

Pawcatuck Basin

Basin total 0.231 0.468 0.037 0.021 0.009 0.053 0.092 1.368 2.279

Table 12. Consumptive water use by town and subbasin in the Pawcatuck Basin, southern Rhode Island and southeastern 

Connecticut, 1995–99.—Continued

[All towns are in Rhode Island unless otherwise noted. Mgal/d, million gallons per day; <0.001, values not included in town and subbasin totals; <, actual value is 

less than value shown; --, not applicable] 

Town/City Domestic (Mgal/d) Commercial (Mgal/d) Industrial

(Mgal/d) Agricultural (Mgal/d) Total 

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

Public-Supply Use

Information on commercial and industrial use of publicsupply 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 have reported the commercial and 

industrial users together, and in other cases the information was 

not available. Governmental 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 district service areas are 

within one or more basins and subbasins, the public-supplied 

commercial and industrial water use were apportioned based on 

land-use area percentages (table 4). Land-use coverages from 

RIGIS were merged with the water-supply, town, and basin 

coverages to obtain the percentage of commercial and industrial 

land use within the supply districts for towns served in the 

Pawcatuck Basin. Commercial use of public-supply water 

ranged from 0 in several subbasins to 0.323 Mgal/d in the 

Lower Pawcatuck subbasin. Industrial use of public-supply 

water ranged from 0 in several subbasins to 0.053 Mgal/d in the 

Chipuxet subbasin.

Self-Supplied Use

Commercial and industrial use of self-supplied water was 

calculated from industrial and commercial directories published 

by the Rhode Island Economic Development Corporation 

(Export/Import Directory, High Tech Industries in Rhode 

Island, and Major Employers in Rhode Island). Commercial 

and industrial water use was estimated for each town by 

identifying the number of employees for the industrial and 

commercial sectors for each SIC code and applying the U.S. 

Army Corp of Engineers’ Institute for Water Resources 

Municipal and Industrial Needs (IWR-MAIN) water-use 

coefficient (in gallons/d/person) for each town (table 13) as 

described in Horn (2000). The estimated commercial and 

industrial entities on public water were subtracted from the total 

aggregate to obtain the estimated total self-supplied use for 

these categories. The results for commercial and industrial 

withdrawals and use are listed in tables 10 and 11. The total 

commercial and industrial water use estimated for a town was 

disaggregated by basin (table 7), and then by subbasin based on 

the industrial and commercial land-use area by town as listed in 

table 3. Commercial use of self-supplied water ranged from 

0.005 Mgal/d (Lower Wood subbasin) to 0.110 Mgal/d in 

the Lower Pawcatuck subbasin (figs. 6 and 7). Industrial 

use of self-supplied water in the Pawcatuck Basin ranged 

from 0.019 Mgal/d in the Usquepaug–Queen subbasin to 

0.177 Mgal/d in the Lower Pawcatuck subbasin (figs. 6 and 7). 

Commercial and industrial water use by subbasin and town are 

listed in table 11.
Water Use 35

Table 13. Estimated water use per 2-digit Standard Industrial Classification code by town in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99.[IWR-MAIN, Institute for Water Resources-Municipal and Industrial Needs; Mgal/d, Million gallons per day; <0.001, values not included in town and subbasin totals; <, actual value is less than value shown; --, not applicable]

2-digit Standard Industrial 

Classification category 

and code

IWRMAIN

coefficient

Estimated water use in Rhode Island towns (Mgal/d) Water use in Connecticut towns (Mgal/d)

Charlestown Coventry Exeter Hopkinton North Kingstown Richmond South Kingstown West Greenwich Westerly North Stonington Sterling Stonington Voluntown

Industrial [20-39]

Food [20] 469 -- -- -- -- 0.011 -- 0.052 -- .006 -- -- 0.002 --Textile mills [22] 315 -- 0.022 -- 0.025 -- 0.137 .008 0.009 .111 -- -- .016 --Finished apparel [23] 13 -- -- -- -- -- -- -- -- -- -- 0.001 -- --Wood, lumber [24] 78 -- -- -- -- .003 -- -- -- -- -- .001 -- --Furniture [25] 30 -- -- -- -- .008 -- -- -- -- -- -- -- --Paper products [26] 863 -- -- -- -- -- -- -- -- -- -- .001 -- --Printing, publishing [27] 42 -- -- -- .001 -- -- -- -- -- -- -- -- --Chemical products [28] 289 -- .102 -- -- .020 -- .003 .068 -- -- -- -- --Petroleum refining [29] 1,045 -- -- -- -- -- -- -- -- -- -- -- -- --Rubber [30] 119 -- -- 0.024 .021 .109 -- -- .003 -- -- -- -- --Leather [31] 148 -- -- -- -- -- -- -- -- -- -- -- -- --Stone, clay, glass, and 

concrete [32]

202 -- -- -- -- -- -- -- -- -- -- -- -- --

Primary metals [33] 178 -- -- -- -- -- -- -- -- .001 -- -- -- --Fabricated metal [34] 95 0.004 -- -- -- .014 -- -- -- -- 0.010 -- -- --Machinery [35] 58 <.001 .009 -- -- .003 .003 -- .058 .012 -- -- -- --Electrical equipment [36] 71 -- -- -- -- .002 -- .110 -- .005 .003 -- .001 --Transportation equipment 

[37]

63 -- -- -- -- .087 -- .001 -- -- -- -- .002 --

Instruments [38] 66 -- .001 -- .001 .030 -- .007 -- -- -- -- -- --Jewelry, precious metals 

[39] 

36 -- .008 -- -- .001 -- -- -- .004 -- -- -- --

Total industrial 

[20-39]

0.004 0.142 0.024 0.048 0.288 0.140 0.181 0.138 0.139 0.013 0.003 0.021 --
36 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99 Commercial [40-97] Transportation, communication, utilities [40-49] 51 -- -- -- -- 0.001 0.006 -- 0.001 0.001 0.003 0.001 0.009 0.001 Wholesale trade [50-51] 58 -- -- -- -- .008 -- -- -- -- .016 .002 .017 .004 Retail trade [52-59] 58 -- 0.034 -- -- .038 .013 0.014 -- .076 .016 .002 .017 .004 Finance, insurance, real estate [60-67] 71 -- -- -- -- -- -- -- -- .028 .003 .001 .011 .001 Services [70-89] 106 0.016 .034 0.017 0.001 .119 -- .365 -- .091 .043 .015 .140 .011 Public administration [91-97] 71 -- -- -- -- .022 -- -- -- -- .005 .001 .021 .001 Total commercial [40-97] 0.016 0.068 0.017 0.001 0.188 0.019 0.379 0.001 0.196 0.086 0.022 0.196 0.022 Table 13. Estimated water use per 2-digit Standard Industrial Classification code by town in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99.—Continued [IWR-MAIN, Institute for Water Resources-Municipal and Industrial Needs; Mgal/d, Million gallons per day; <0.001, values not included in town and subbasin totals; <, actual value is less than value shown; --, not applicable] 2-digit Standard Industrial Classification category and code IWR- MAIN coeffi- cient Estimated water use in Rhode Island towns (Mgal/d) Water use in Connecticut towns (Mgal/d) Charlestown Coventry Exeter Hopkinton North Kingstown Richmond South Kingstown West Greenwich Westerly North Stonington Sterling Stonington Voluntown
Water Use 37

Agricultural Water Use

The estimated agricultural water use (livestock, crop 

irrigation, and golf-course irrigation) was obtained from 

information provided from the Department of Agriculture 

(USDA), Natural Resources Conservation Service (NRCS) 

formerly the Soil Conservation Service (SCS), and the RIDEM 

Division of Agriculture. The estimated value was calculated for 

each town and then disaggregated into the State basins and 

subbasins. Livestock withdrawals and use were assumed to be 

9 percent from surface water (streams and ponds) and 82 

percent from ground water (wells) based on previously 

estimated statewide livestock water use from the former Soil 

Conservation Service (1993), which is now referred to as the 

NRCS. Withdrawals and use for irrigation (golf courses and 

crops) were assumed to be 81 percent from surface water and 13 

percent from ground water, based on previously estimated 

statewide irrigation water use (Soil Conservation Service, 

1993). The remaining 9 percent of livestock use and 6 percent 

of irrigation use is assumed to be from public-supply 

distributions. Consumptive water use for agriculture was 

assumed to be 100 percent (table 11).

Livestock water requirements are also included in 

agricultural water use and include water-use estimates for each 

type of livestock (Laura Medalie, U.S. Geological Survey, 

written commun., 1995) multiplied by the number of livestock. 

Because the livestock and crop-irrigation data are reported 

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

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

disaggregated by town and then basin on the basis of the 

number of farms in the town and the percentage of agricultural 

land use by town and by basin. The livestock water-use 

estimates represent a year-round usage. For this study, 

agricultural water use is assumed to be 100 percent consumed 

based on previous investigations (Horn and others, 1994). 

While it is estimated that 60 percent of livestock water use is 

consumptive, and 40 percent is returned to the ground water 

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

subbasins in the Pawcatuck Basin. Livestock water use is minor 

in the basin, accounting for about 1.6 percent of the agricultural 

water use during the summer and about 3.4 percent of the 

agricultural water use during the study period.

Crop and golf-course irrigation were estimated with a 

method derived by the USGS water-use specialists in Vermont 

and New Hampshire during previous water-use compilations 

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

2000). The percentage of agricultural land-use area for each 

town in the county was estimated on the basis of the agricultural 

land-use area in each town. The town acreage determined was 

subdivided by basin and subbasin. For the resulting acreage of 

crop irrigation for the portions of the towns in the Pawcatuck 

Basin, the coefficient determined by the SCS (1993) for the 

Pawcatuck Basin was applied. Crop acreage irrigated in the 

Pawcatuck Basin was assumed to be turf farming. For irrigated 

acreage for land areas in towns outside of the Pawcatuck Basin, 

it was assumed that 1 in/week/acre of water was needed to 

irrigate crop land, an average of 0.143 in/day/acre. The monthly 

deficiency of water was determined by subtracting the average 

monthly rainfall from the 0.143 in/day/acre needed for crop 

irrigation in the remaining basins in the State. Yardages for the 

golf courses, all of which are in Rhode Island, were collected 

by using the Web sites from WorldGolf.com (2002) and 

GolfCourse.com (2002). The coefficient of 0.0116 Mgal/d per 

1,000 yards (Laura Medalie, U.S. Geological Survey, written 

commun., 2000) was applied to the golf courses for the towns 

in the Pawcatuck Basin. This coefficient used for this study was 

comparable to the metered (or reported) withdrawal data 

summarized for the 2000 water-use compilation for 

Massachusetts, where the average withdrawals were 

approximately 0.0117 Mgal/d per 1,000 yards. According to the 

SCS (1993), most of the irrigation occurred during June, July, 

and August; therefore, it was assumed that crop- and golfcourse-irrigation water was used during these months. A 

concurrent USGS study is presently (2003) collecting data on 

crop and golf-course irrigation; however, the data were 

unavailable at the time of the data collection process for this 

study.

In the Pawcatuck Basin, some agricultural water use 

was from public-supply water. In the Kingston Water District, 

agricultural water use was one of the largest uses, consuming 

an average of 21 percent of the water distributions, and 

0.092 Mgal/d in the basin during the study period (table 11). 

Self-supplied agricultural water use was estimated to 

obtain the self-supplied water use by town and disaggregated by 

basin and subbasin. Self-supplied water withdrawals and use for 

agricultural ranged from 0.147 Mgal/d in the Beaver–Pasquiset 

subbasin to 0.402 Mgal/d in the Lower Wood subbasin (figs. 6 

and 12, tables 10 and 11). 

Return Flow and Interbasin Transfers

In Rhode Island, commercial and industrial dischargers 

are required to report to the RIDEM Office of Water Resources 

the rates of water returned to the environment into surface 

water (usually to rivers) and ground water. The surface-water 

return flow in the Pawcatuck Basin was 4.505 Mgal/d, and 

the estimated ground-water return flow was 3.350 Mgal/d 

(table 14).
38 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Table 14. Estimated public- and self-disposed domestic, commercial, and industrial, and metered return flow by subbasin in the 

Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99.

[All towns are in Rhode Island unless otherwise noted. Public disposal: Wastewater collection to treatment plant. Self-disposal: Inflow to ground water. RIPDES 

and wastewater treatment facilities: Inflow to surface water. RIPDES, Rhode Island Pollution Discharge Elimination System; Mgal/d, million gallons per day; 

<0.001, values not included in town and subbasin totals; <, actual value less than value shown; --, not applicable]

Town

Estimated

domestic disposal

(Mgal/d)

Estimated

commercial disposal

(Mgal/d)

Estimated

industrial disposal

(Mgal/d)

Metered return flow Total

self-disposal

and return flow

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

Wastewatertreatment 

facilities

Chipuxet Subbasin

Charlestown 0.002 0.014 -- -- -- -- -- -- 0.014

Exeter .003 .050 -- 0.003 -- 0.010 -- -- .063

North Kingstown <.001 .044 -- <.001 -- .002 -- -- .046

Richmond -- .020 -- .001 -- -- -- -- .021

South Kingstown .341 .254 0.021 .059 0.053 .092 -- -- .405

Subbasin total 0.346 0.382 0.021 0.063 0.053 0.104 -- -- 0.549

Usquepaug–Queen Subbasin

East Greenwich <0.001 0.002 -- -- -- -- -- -- 0.002

Exeter .005 .182 -- 0.005 -- 0.002 0.003 -- .192

North Kingstown .001 .008 -- .004 -- -- -- -- .012

Richmond -- .049 -- .001 -- -- -- -- .050

South Kingstown -- .028 -- .002 -- -- -- -- .030

West Greenwich -- .015 -- -- -- .015 -- -- .030

Subbasin total 0.006 0.284 -- 0.012 -- 0.017 0.003 -- 0.316

Beaver–Pasquiset Subbasin

Charlestown 0.008 0.086 -- 0.003 -- 0.002 -- -- 0.091

Exeter -- .017 -- .005 -- -- -- -- .022

Richmond -- .141 -- .001 -- .024 0.318 -- .484

South Kingstown <.001 .002 -- -- -- -- -- -- .002

Subbasin total 0.008 0.246 -- 0.009 -- 0.026 0.318 -- 0.599

Upper Wood Subbasin

Coventry -- 0.004 -- -- -- -- -- -- 0.004

Exeter 0.002 .066 -- 0.002 -- 0.010 -- -- .078

Hopkinton .006 .126 -- .001 -- .014 0.005 -- .146

North Stonington, CT -- -- -- -- -- -- -- -- --

Richmond -- .068 -- .034 -- .060 .009 -- .171

Sterling, CT .004 .024 -- -- -- -- -- -- .024

Voluntown, CT <.001 .012 -- -- -- <.001 -- -- .012

West Greenwich .002 .073 -- <.001 -- .034 -- -- .107

Subbasin total 0.014 0.373 -- 0.037 -- 0.118 0.014 -- 0.542
Water Use 39

Lower Wood Subbasin

Charlestown <0.001 0.081 -- <0.001 -- 0.002 0.513 -- 0.596

Hopkinton .006 .093 -- <.001 -- .007 -- -- .100

North Stonington, CT -- -- -- -- -- -- -- -- --

Richmond -- .123 -- .005 -- .042 .243 -- .413

Voluntown, CT -- <.001 -- -- -- <.001 -- -- <.001

Subbasin total 0.006 0.297 -- 0.005 -- 0.051 0.756 -- 1.109

Lower Pawcatuck Subbasin

Charlestown 0.001 0.062 -- <0.001 -- -- -- -- 0.062

Hopkinton .007 0.229 -- .001 -- 0.022 0.564 -- .816

North Stonington, CT .006 .224 -- -- -- .012 -- -- .236

Stonington, CT .195 .107 -- -- -- .001 -- 0.505 .613

Voluntown, CT -- .013 -- -- -- <.001 -- -- .013

Westerly .733 .432 0.291 .098 0.035 .125 .001 2.344 3.000

Subbasin total 0.942 1.067 0.291 0.099 0.035 0.160 0.565 2.849 4.740

Pawcatuck Basin

Basin total 1.322 2.649 0.312 0.225 0.088 0.476 1.656 2.849 7.855

Table 14. Estimated public- and self-disposed domestic, commercial, and industrial, and metered return flow by subbasin in the 

Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99.—Continued

[All towns are in Rhode Island unless otherwise noted. Public disposal: Wastewater collection to treatment plant. Self-disposal: Inflow to ground water. RIPDES 

and wastewater treatment facilities: Inflow to surface water. RIPDES, Rhode Island Pollution Discharge Elimination System; Mgal/d, million gallons per day; 

<0.001, values not included in town and subbasin totals; <, actual value less than value shown; --, not applicable]

Town

Estimated

domestic disposal

(Mgal/d)

Estimated

commercial disposal

(Mgal/d)

Estimated

industrial disposal

(Mgal/d)

Metered return flow Total

self-disposal

and return flow

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

Wastewatertreatment 

facilities

Site-Specific Return Flow

Small systems in Rhode Island that release water back to 

the environment are identified through the RIDEM Rhode 

Island Pollutant Discharge Elimination System (RIPDES), and 

some are required to report their discharges. Return-flow data 

were collected from RIDEM for these small systems in the 

Pawcatuck Basin (table 15). Data from individual treatment 

facilities, for example the wastewater-treatment plants, were 

collected, as recommended by Horn and Craft (1991). 

Discharge pipes dispose of water used during industrial and 

commercial processes (operations), but also include water 

condensation from air-conditioning systems. The total of 

RIPDES discharges in the Pawcatuck Basin was 1.656 Mgal/d, 

and ranged from 0.003 Mgal/d in the Usquepaug–Queen 

subbasin to 0.756 Mgal/d in the Lower Wood subbasin 

(table 15). There were no RIPDES sites in the Chipuxet 

subbasin during the 1995 through 1999 study period. 

Monthly data were collected for public disposal 

wastewater-treatment facilities in or serving the towns in the 

Pawcatuck Basin (table 16). The wastewater-treatment facilities 

serving populations in the Pawcatuck Basin include the South 

Kingstown Wastewater-Treatment Facility, the Stonington 

Wastewater Pollution-Control Facility at Pawcatuck, and the 

Westerly Wastewater-Treatment Facility. The Westerly 

Wastewater-Treatment Facility is within the basin, discharges 

to the Pawcatuck River, and serves the community of Westerly. 

The average discharge for the study period to the Pawcatuck 

River from the Westerly system was 2.344 Mgal/d (table 16). 

The Stonington facility serves the village of Pawcatuck in the 

town of Stonington, CT, and the facility discharged an average 

of 0.505 Mgal/d. The South Kingstown Wastewater-Treatment 

Facility is in the West Narragansett Bay Drainage Basin, and 

accepts wastewater from populations in the Pawcatuck Basin.
40 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Table 15. Return flows by subbasin for the Rhode Island Pollutant Discharge Elimination System sites in the Pawcatuck Basin, southern 

Rhode Island and southeastern Connecticut, 1995–99.

[Reference number: The identifier for the site on figure 5. SIC, Standard Identification Code; WWTF, Wastewater-treatment facility; Mgal/d, Million gallons per 

day; <0.001, values not included in totals; <, actual value less than value shown--, not applicable]

Return-flow site Reference

number

Town

(locality)

Discharge 

permit

number

Receiving water body SIC code

Return flow

1995–99

(Mgal/d)

Chipuxet Subbasin

-- -- -- -- -- -- --

Subbasin total --

Usquepaug–Queen Subbasin

Ladd School WWTF 1 Exeter RI0100081 Queen River Tributary 8211 0.003

Subbasin total 0.003

Beaver–Pasquiset Subbasin

Kenyon Industries, Inc. 2 Richmond (Kenyon) RI000191 Pawcatuck River 2269 0.318

Subbasin total 0.318

Upper Wood Subbasin

Mobil Service Station 3 Richmond RI0090174 Pawcatuck River 7542 0.009

Rhode Island Department of 

Transportation

4 Hopkinton RI0022136 Unnamed Tributary to 

the Wood River

4173 .005

Subbasin total 0.014

Lower Wood Subbasin

0

Carolina Trout Hatchery 5 Charlestown (Carolina) RI0001007 White Brook 0921 0.513

Coastal Plastics 6 Hopkinton (Hope Valley) RI0022080 Wood River 3089 .014

Green Plastics 7 Hopkinton (Hope Valley) RI0001252 Canochet Brook 3081 .229

Subbasin total 0.756

Lower Pawcatuck Subbasin

Ashaway Line and Twine 

Manufacturing Company

8 Hopkinton (Ashaway) RI0021814 Ashaway River 2298 <0.001

Bradford Dye Company 9 Hopkinton (Bradford) RI0000043 Pawcatuck River 2261 .545

The Imperial Home Decor 

Group

10 Hopkinton (Ashaway) RI0020508 Pawcatuck River 5023 .019

Mobil Service Station 11 Westerly RI0022098 Pawcatuck River 7542 .001

Subbasin total 0.565

Pawcatuck Basin

Basin total 1.656
Water Use 41

ESTIMATED DOMESTIC

WATER USE

1.772 Mgal/d

ESTIMATED INDUSTRIAL

WATER USE

0.039 Mgal/d

ESTIMATED COMMERCIAL

WATER USE

0.323 Mgal/d

EXPORTS TO COASTAL

DRAINAGE BASIN

(WESTERLY)

0.288 Mgal/d

WESTERLY WATER

DEPARTMENT

DISTRIBUTION

3.236 Mgal/d

NON-ACCOUNT

WATER USE

0.813 Mgal/d

WELL FIELD 1

0.845 Mgal/d

WELL FIELD 2

1.081 Mgal/d

WELL #3 

0.432 Mgal/d

BRADFORD II WELL

0.270 Mgal/d

BRADFORD III WELL

0.281 Mgal/d

CRANDALL WELL

0.327 Mgal/d

NOYES AVENUE

WELL

(Emergency Only)

Pawcatuck Basin

Basin Export

EXPLANATION

Mgal/d Million Gallons Per Day

Figure 13. Westerly Water Department withdrawals, distributions, and estimated water uses in the Pawcatuck Basin and 

basin exports, southern Rhode Island and southeastern Connecticut, 1995–99.
42 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Table 16. Return flow from wastewater-treatment facilities within and outside of the Pawcatuck Basin, southern Rhode Island and 

southeastern Connecticut, 1995–99.

[Mgal/d, Million gallons per day] 

Wastewater-treatment facility

Discharge

permit

number

Receiving water body

(subbasin or basin)

Average

discharge

1995–99

(Mgal/d)

Return flow to the Pawcatuck Basin

Stonington Pawcatuck Water Pollution-Control Authority CT0101290 Pawcatuck River (Lower Pawcatuck subbasin) 0.505

Westerly Wastewater-Treatment Facility RI0100064 Pawcatuck River (Lower Pawcatuck subbasin) 2.344

Total 2.849

Return flow outside of the Pawcatuck Basin

South Kingstown Regional Wastewater-Treatment Facility RI0100374 West Narragansett Bay Drainage Basin 2.639

Total 2.639

Aggregate Return Flow

Aggregate return flow 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) (table 1). It was assessed that 

85 percent of the water used by domestic populations on septic 

systems was returned to ground water, based on the estimate 

that 15 percent of the water used was consumed (Solley and 

others, 1998). To estimate the amount of domestic self-disposed 

water, the population was multiplied by the water-use 

coefficient for self-supplied water use (71 gal/d/person), 

converted to Mgal/d, and multiplied by the 85 percent. The 

results for the domestic self-disposed water are summarized 

by town and subbasin in table 14, and illustrated by subbasin 

in figure 13. The other 15 percent of the water was assumed 

to be consumed (table 12). It is estimated that 90 percent of 

industrial and commercial return flow is disposed to ground 

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

A summary of the consumptive water use for domestic, 

commercial, industrial, and agricultural water users by subbasin 

is in table 12, and a summary of the return flow is in table 14. 

Interbasin Transfers

Wastewater collected from South Kingstown and treated at 

the South Kingstown facility was exported from the Pawcatuck 

Basin to the West Narragansett Bay Drainage Basin. Estimated 

populations on public disposal systems (table 1) and estimated 

publicly disposed industrial and commercial water from the 

Kingston Water District, URI, and UWRI (based on 80 percent 

of the water used in the Pawcatuck Basin) were used to 

determine the water exports, which resulted in approximately 

2.487 Mgal/d exported from the basin (table 17). The total 

wastewater disposal from the South Kingstown facility was 

2.639 Mgal/d, which discharges to West Narragansett Bay 

Drainage Basin (table 14). Also, parts of the wastewatercollection areas for Stonington and Westerly are outside of the 

Pawcatuck Basin, and about 2.080 Mgal/d of the wastewater is 

imported to the basin (table 17). Within the balance of the water 

withdrawals, use, unaccounted, 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 are metered (or 

reported), for example, but the use by subbasin is estimated, and 

then the return flow is metered (or reported) and estimated. 

Similarly, RIPDES data are metered (or reported) but the 

withdrawal and use is estimated. 
Water Availability 43

Table 17. Summary of estimated water withdrawals, imports, exports, use, non-account water use, consumptive use, and return flow in 

the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99.

[Non-account: A loss of water through the water-supply system. Consumptive use: A basin export. Net imports and exports: The sum of the potable 

water and wastewater imports and exports; does not include non-account and consumptive water uses. AG, agricultural; COM, commercial; DOM, domestic; 

IND, industrial; Mgal/d, million gallons per day; <0.001, values not included in town and subbasin totals; +, potable distribution and wastewater collection 

imported to subbasin and basin; -, potable distribution and wastewater collection exported from subbasin and basin; <, actual value is less than value shown; 

--, water use not applicable]

Subbasin

Total water 

withdrawals

(Mgal/d)

Potable

water

imports (+)

and

exports (-) 

(Mgal/d)

Total water use, public 

and self (Mgal/d) Consumptive use 

(Mgal/d)

Return flow 

(Mgal/d) Wastewater 

imports (+) and 

exports (-) 

(Mgal/d)

Net

imports (+)

and exports (-) 

(Mgal/d) 

Use 

(DOM, 

COM,

IND, AG)

Nonaccount 

(public use)

Surface 

water

Ground 

water

Chipuxet 4.212 -2.258 1.406 0.548 0.453 -- 0.549 -0.404 -2.662

Usquepaug–Queen .674 +.006 .680 -- .362 0.003 .313 -.002 +.004

Beaver–Pasquiset .463 +.019 .482 -- .195 .318 .281 +.312 +.331

Upper Wood .779 +.008 .786 .001 .241 .014 .528 -.003 +.005

Lower Wood .819 +.002 .821 -- .462 .756 .353 +.750 +.752

Lower Pawcatuck 4.303 -.264 3.226 .813 .566 3.414 1.326 +2.080 +1.816

Pawcatuck Basin total 11.25 -2.487 7.401 1.362 2.279 4.505 3.350 +2.733 +0.246

Water Availability

During periods of little or no precipitation, streamflow is 

mostly from ground-water discharges, base flow, and direct 

run-off is assumed to be negligible. The computerized PART 

method (Rutledge, 1993, 1998) was used to obtain groundwater discharge to the streams during periods of little or no 

precipitation in the summer. Because water withdrawals can be 

higher during the summer, whereas the precipitation and 

ground-water discharge may be lower than average for the year, 

the ratio of the water withdrawals to water availability was 

assessed to determine the net availability of the water 

withdrawals to the hydrologic system during June, July, 

August, and September for the Pawcatuck Basin and subbasins. 

In addition, streamflow-depletion methods were applied to 

selected water-supply wells, and basin and subbasin water 

budgets for the study period were determined.

The water availability during times of little or no 

precipitation can be determined with streamflow data collected 

at the selected index stream-gaging stations. Water-availability 

estimates made from base-flow calculations are conservative 

estimates; actual streamflows are generally greater than 

base flow except for periods of little or no recharge from 

precipitation. In the Pawcatuck Basin, at least one streamgaging station in each subbasin has at least 10 years of data 

(table 18). For the Lower Pawcatuck subbasin, however, the 

Pawcatuck River at Wood River Junction stream-gaging station 

(01117500) in the Lower Wood subbasin was used because of 

the regulation upstream of the Pawcatuck River at Westerly 

stream-gaging station (01118500). In addition to the Wood 

River Junction station, data from four other stream-gaging 

stations were used to determine water availability in the 

Chipuxet, Usquepaug–Queen, Beaver–Pasquiset, and Upper 

Wood subbasins: the Chipuxet River at West Kingston (station 

01117350), Usquepaug River near Usquepaug (station 

01117420), Beaver River near Usquepaug (station 01117468), 

and Wood River near Arcadia (station 01117800), respectively. 

The PART program, a hydrograph-separation application, 

was used at the selected index stations to determine water 

availability based on the 75th, 50th, and 25th percentiles of the 

total base flow, the base flow minus the 7-day, 10-year flow 

(7Q10) criterion at the index station, and the base flow minus 

the Aquatic Base Flow (ABF) criterion at the index station 

(table 19). During the summer, portions of ground water drain 

out of the Pawcatuck Basin upstream of the Chipuxet and 

Usquepaug–Queen stream-gaging stations. For these stations, 

the program was run by using the surface-water drainage area, 

but the ground-water drainage areas were used for the base flow 

at the other stations. The differences in the surface and 

subsurface drainage areas in the summer were applied to the 

water availability calculated at the subbasins (table 5).
44 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Table 18. U.S. Geological Survey stream-gaging stations and minimum streamflows in the Pawcatuck Basin, southern Rhode Island and 

southeastern Connecticut.

[USGS stream-gaging station number: Identifier used in figure 5. Drainage area: Station drainage areas are from Socolow and others (2001). Mean flow: 

Water years are from October to September and may vary from the period of record in the data report. Minimum flows: 7Q10, 7-day, 10-year flow (G.W. Parker, 

U.S. Geological Survey, written commun., 2002); ABF, Aquatic Base Flow, based on the median of the monthly means; USGS, U.S. Geological Survey; Mgal/d, 

million gallons per day]

USGS stream-gagingstation number Station name

Drainage

area

(mi2)

Mean flow 

(Mgal/d)

[water years] 

Minimum flows (Mgal/d)

7Q10

[water years]

ABF

[water years]

01117350 Chipuxet River at West Kingston, RI 9.99 13.71

[1974–2000]

0.957

[1959–2001]

5.994

[1974–2000]

01117420 Usquepaug River near Usquepaug, RI 36.1 49.59

[1975–2000]

3.608

[1959–2002]

18.30

[1975–2000]

01117468 Beaver River near Usquepaug, RI 8.87 13.77

[1975–2000]

1.093

[1976–2002]

4.746

[1975–2000]

01117500 Pawcatuck River at Wood River 

Junction, RI

100 126.7

[1941–2000]

17.07

[1942–2002]

45.45

[1941–2000]

01117800 Wood River near Arcadia, RI 35.2 49.53

[1964–1981; 

1983–2000]

4.209

[1964–1981;

1983–2000]

13.84

[1964–1981;

1983–2000]

01118500 Pawcatuck River at Westerly, RI 295 373.1

[1941–2000]

41.83

[1942–2002]

115.1

[1941–2000]

Contributions of base flow from surficial deposits, till, and 

stratified sand and gravel for the index stations are based on 

previous work by the U.S. Geological Survey. The base-flow 

contributions from sand and gravel deposits at the index stations 

were 67 percent at the Chipuxet stream-gaging station 

(Johnston and Dickerman, 1985), 71 percent at the Usquepaug 

and Wood River Junction stream-gaging stations (Dickerman 

and others, 1997), 52 percent at the Beaver stream-gaging 

station (Gonthier and others, 1974), and 57 percent at the 

Arcadia stream-gaging station (Dickerman and Bell, 1993). The 

base-flow contributions from till deposits at the index stations 

were 33 percent at the Chipuxet stream-gaging station, 29 

percent at the Usquepaug and Wood River Junction streamgaging stations, 48 percent at the Beaver stream-gaging station, 

and 43 percent at the Arcadia stream-gaging station. The two 

contributions for June, July, August, and September were 

applied to the percentage of surficial deposits at each index 

station, and converted into a per unit area rate for the till areas 

and sand and gravel areas in the subbasins. The scenarios used 

to estimate the gross yield of base flow, as well as subtracting 

out the two low-flow criterias, resulted in various watervailability values at each index station, which were present in 

the subbasin after applying the per unit area rates from the index 

station (table 19). 
Water Availability 45

Table 19. Summer water availability for selected stream-gaging stations in the Pawcatuck Basin, southern Rhode Island and 

southeastern Connecticut.

[7Q10, 7-day, 10-year flow; ABF, Aquatic Base Flow, based on the median of the August monthly means; Mgal/d, million gallons per day; --, values less than 

zero and not used]

Summer base 

flow for 

selected index 

stations

Estimated gross yield

(Mgal/d)

Estimated gross yield minus 7Q10 

(Mgal/d)

Estimated gross yield minus ABF 

(Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet Stream-Gaging Station

June 14.01 9.273 6.653 13.04 8.303 5.683 8.020 3.279 0.660

July 8.822 4.918 3.676 7.852 3.948 2.706 2.828 -- --

August 7.123 5.070 3.296 6.153 4.100 2.326 1.130 -- --

September 5.134 4.191 3.012 4.164 3.221 2.043 -- -- --

Usquepaug Stream-Gaging Station

June 44.80 25.68 21.03 41.19 22.07 17.42 26.50 7.383 2.735

July 21.00 15.95 10.85 17.40 12.34 7.242 2.706 -- --

August 17.85 12.80 8.068 14.24 9.189 4.460 -- -- --

September 16.39 11.02 7.570 12.78 7.412 3.962 -- -- --

Beaver Stream-Gaging Station

June 14.94 8.865 7.158 13.84 7.772 6.065 10.19 4.119 2.412

July 6.505 5.121 3.718 5.412 4.028 2.625 1.759 .375 --

August 5.334 3.653 2.399 4.242 2.560 1.306 .588 -- --

September 4.358 3.188 2.160 3.265 2.065 1.067 -- -- --

Arcadia Stream-Gaging Station

June 41.41 28.46 21.42 37.21 24.25 17.22 27.57 14.62 7.582

July 20.38 16.09 11.65 16.18 11.89 7.445 6.546 2.252 --

August 20.73 11.55 9.624 16.52 7.346 5.421 6.891 -- --

September 16.22 11.63 9.179 12.01 7.425 4.977 2.381 -- --

Wood River Junction Stream-Gaging Station

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 -- --
46 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Summer Water Availability by Subbasin

The water-availability estimates from the contributions of 

sand and gravel deposits and till deposits for all the scenarios at 

the 75th, 50th, and 25th percentiles in the Pawcatuck Basin and 

subbasins are presented in table 20. The water-availability 

estimates in July from sand and gravel deposits at the 50th 

percentile for the gross yield were 98.43, Mgal/d and 52.26 

from the till deposits in the Pawcatuck Basin. By using the 7-

day, 10-year low-flow criteria, the water-availability estimates 

in July from sand and gravel deposits at the 50th percentile for 

the gross yield were 72.25 Mgal/d, and 37.56 from the till 

deposits in the Pawcatuck Basin. (Total surficial deposits for the 

subbasins are presented in table 21.) The water availability from 

sand and gravel deposits for June, July, August, and September 

by subbasin at the 50th percentile for the gross yield, 7-day, 

10-year low-flow criteria and Aquatic Base Flow criteria are 

illustrated in figure 14. The water availability from till deposits 

for June, July, August, and September by subbasin at the 50th 

percentile for the gross yield, 7-day, 10-year low-flow and 

Aquatic Base Flow criteria are illustrated in figure 15. 

The water availability from sand and gravel deposits and till 

deposits for June, July, August, and September by subbasin 

at the 50th percentile for the gross yield, 7-day, 10-year lowflow and Aquatic Base Flow criteria are illustrated in figure 16. 

Although the water availabilities were lower in September 

(Chipuxet, Usquepaug–Queen, Beaver–Pasquiset, Lower 

Wood, and Lower Pawcatuck subbasins) and August (Upper 

Wood subbasin) at the 50th percentile for the gross yield, there 

were more withdrawals in July (Chipuxet and Lower 

Pawcatuck subbasins) and August (Usquepaug–Queen, 

Beaver–Pasquiset, Upper Wood, and Lower Wood subbasins) 

than in September in the basin (table 22). The analysis of the 

water withdrawals-to-availabilities resulted in higher ratios in 

July (Chipuxet subbasin) and August (Usquepaug–Queen, 

Beaver–Pasquiset, Upper Wood, Lower Wood, and Lower 

Pawcatuck subbasins). The ratios of water withdrawals to 

availabilities for June, July, August, and September pertaining 

to the basin and subbasins are presented in table 23. The 

variation of the water withdrawal-to-availability ratios in the 

subbasins for July, August, and September are illustrated in 

figure 17. Water-availability estimates and water withdrawal to 

availability ratios were calculated for each subbasin. The 

cumulative withdrawals from upstream subbasins have not been 

accounted for in the water-availability calculations for the 

downstream subbasins. 

In the Chipuxet subbasin, the estimated water 

availability for the gross yield at the 50th percentile ranged from 

17.00 Mgal/d in September to 37.60 Mgal/d in June for the 

contributions from sand and gravel deposits, and ranged 

from 3.698 Mgal/d in September to 8.182 Mgal/d in June 

for the contributions from till deposits (table 20). The water 

availability in the subbasin at the 50th percentile for the 

gross yield ranged from 20.70 Mgal/d in September to 

45.78 Mgal/d in June, and by using the 7Q10 criteria, ranged 

from 15.90 Mgal/d in September to 41.00 Mgal/d in June 

(table 21). The average water withdrawals for the Chipuxet 

subbasin ranged from 4.141 Mgal/d in September to 

5.972 Mgal/d in July for the study period (table 22). The results 

for the ratios for the gross-yield scenario at the 50th percentile 

ranged from 0.109 in June to 0.252 in July, and by using the 

7Q10 criteria, the ratios ranged from 0.121 in June to 0.314 in 

July (table 23).

In the Usquepaug–Queen subbasin, the estimated 

water availability for the gross yield at the 50th percentile 

ranged from 7.824 Mgal/d in September to 18.23 Mgal/d in 

June for the contributions from sand and gravel deposits, and 

ranged from 3.196 Mgal/d in September to 7.447 Mgal/d in 

June for the contributions from till deposits (table 20). The 

water availability in the subbasin at the 50th percentile for 

the gross yield ranged from 11.02 Mgal/d in September to 

25.68 Mgal/d in June, and by using the 7Q10 criteria, ranged 

from 7.411 Mgal/d in September to 22.07 Mgal/d in June 

(table 21).The average water withdrawals for the Usquepaug–

Queen subbasin ranged from 0.521 Mgal/d in September to 

1.421 Mgal/d in August for the study period (table 22). The 

results for the ratios for the gross-yield scenario at the 50th 

percentile ranged from 0.032 in June to 0.111 in August, and by 

using the 7Q10 criteria, the ratios ranged from 0.038 in June to 

0.155 in August (table 23).

In the Beaver–Pasquiset subbasin, the estimated water 

availability for the gross yield at the 50th percentile ranged from 

7.200 Mgal/d in September to 20.02 Mgal/d in June for the 

contributions from sand and gravel deposits, and ranged from 

2.913 Mgal/d in September to 8.102 Mgal/d in June for the 

contributions from till deposits (table 20). The water availability in the subbasin at the 50th percentile for the gross yield 

ranged from 10.11 Mgal/d in September to 28.12 Mgal/d in 

June, and by using the 7Q10 criteria, ranged from 6.647 Mgal/d 

in September to 24.65 Mgal/d in June (table 21).The average 

water withdrawals for the Beaver–Pasquiset subbasin ranged 

from 0.388 Mgal/d in September to 0.831 Mgal/d in August for 

the study period (table 22). The results for the ratios for the 

gross-yield scenario at the 50th percentile ranged from 0.019 in 

June to 0.072 in August, and by using the 7Q10 criteria the 

ratios ranged from 0.022 in June and 0.102 in August (table 23).

In the Upper Wood subbasin, the estimated water 

availability for the gross yield at the 50th percentile ranged 

from 12.80 Mgal/d in August to 31.55 Mgal/d in June for 

the contributions from sand and gravel deposits, and ranged 

from 10.55 Mgal/d in August to 25.99 Mgal/d in June for 

the contributions from till deposits (table 20). The water 

availability in the subbasin at the 50th percentile for the gross 

yield ranged from 23.35 Mgal/d in August to 57.54 Mgal/d in 

June, and by using the 7Q10 criteria, ranged from 14.85 Mgal/d 

in August to 49.04 Mgal/d in June (table 21).The average water 

withdrawals for the Upper Wood subbasin ranged from 

0.702 Mgal/d in September to 1.175 Mgal/d in August for the 

study period (table 22). The results for the ratios for the grossyield scenario at the 50th percentile ranged from 0.015 in June 

to 0.050 in August, and by using the 7Q10 criteria, the ratios 

ranged from 0.018 in June to 0.079 in August (table 23).
Water Availability 47

Table 20. Estimated gross yield, gross yield minus the 7-day, 10-year flow, and gross yield minus the Aquatic Base Flow of water 

availability for June, July, August, and September in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut.

[7Q10, 7-day, 10-year flow; ABF, Aquatic Base Flow; Mgal/d, million gallons per day; --, values at station less than zero and not used]

Subbasin

Estimated gross yield for June 

(Mgal/d) 

Estimated gross yield minus

7Q10 for June (Mgal/d)

Estimated gross yield minus

ABF for June (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Estimated Yields from Sand and Gravel Deposits

Chipuxet subbasin1 56.83 37.60 26.98 52.90 33.67 23.05 32.53 13.30 2.675

Usquepaug–Queen subbasin2 31.81 18.23 14.93 29.25 15.67 12.37 18.82 5.242 1.942

Beaver–Pasquiset subbasin3 33.73 20.02 16.17 31.27 17.55 13.70 23.02 9.303 5.447

Upper Wood subbasin4 45.91 31.55 23.75 41.25 26.89 19.09 30.57 16.21 8.406

Lower Wood subbasin5 30.18 23.63 18.82 25.72 19.17 14.36 18.30 11.75 6.939

Lower Pawcatuck subbasin5 54.77 42.88 34.15 46.68 34.79 26.06 33.21 21.32 12.60

Total estimated yields from 

sand and gravel deposits 

253.2 173.9 134.8 227.1 147.7 108.6 156.4 77.12 38.01

Estimated Yields from Till Deposits

Chipuxet subbasin1 12.37 8.182 5.870 11.51 7.326 5.015 7.076 2.893 0.582

Usquepaug–Queen subbasin2 12.99 7.447 6.100 11.95 6.401 5.053 7.685 2.141 .793

Beaver–Pasquiset subbasin3 13.65 8.102 6.542 12.65 7.103 5.543 9.313 3.764 2.204

Upper Wood subbasin4 37.82 25.99 19.56 33.98 22.15 15.72 25.18 13.35 6.924

Lower Wood subbasin5 12.07 9.448 7.525 10.28 7.664 5.741 7.317 4.698 2.775

Lower Pawcatuck subbasin5 41.76 32.70 26.04 35.59 26.52 19.87 25.32 16.26 9.603

Total estimated yields from 

till deposits 

130.7 91.87 71.64 116.0 77.16 56.94 81.90 43.11 22.88

Estimated gross yields 383.9 265.8 206.4 343.1 224.9 165.5 238.3 120.2 60.89

Subbasin

Estimated gross yield for July 

(Mgal/d) 

Estimated gross yield minus

7Q10 for July (Mgal/d)

Estimated gross yield minus

ABF for July (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Estimated Yields from Sand and Gravel Deposits

Chipuxet subbasin1 35.78 19.94 14.91 31.84 16.01 10.97 11.47 -- --

Usquepaug–Queen subbasin2 14.91 11.33 7.703 12.35 8.763 5.142 1.921 -- --

Beaver–Pasquiset subbasin3 14.69 11.57 8.397 12.22 9.098 5.929 3.972 0.847 --

Upper Wood subbasin4 22.60 17.84 12.91 17.94 13.18 8.254 7.257 2.497 --

Lower Wood subbasin5 17.37 13.41 10.81 12.91 8.951 6.348 5.489 1.532 --

Lower Pawcatuck subbasin5 31.52 24.34 19.62 23.43 16.25 11.52 9.963 2.781 --

Total estimated yields from 

sand and gravel deposits 

136.9 98.43 74.35 110.7 72.25 48.16 40.07 7.657 --

Estimated Yields from Till Deposits

Chipuxet subbasin1 7.784 4.339 3.243 6.928 3.483 2.388 2.495 -- --

Usquepaug–Queen subbasin2 6.091 4.626 3.146 5.045 3.579 2.100 .785 -- --

Beaver–Pasquiset subbasin3 5.945 4.680 3.398 4.946 3.682 2.399 1.607 0.343 --

Upper Wood subbasin4 18.61 14.69 10.64 14.78 10.85 6.798 5.978 2.057 --

Lower Wood subbasin5 6.945 5.363 4.323 5.161 3.579 2.539 2.195 .613 --

Lower Pawcatuck subbasin5 24.04 18.56 14.96 17.86 12.39 8.786 7.597 1.120 --

Total estimated yields from till 

deposits 

69.42 52.26 39.71 54.72 37.56 25.01 20.66 4.133 --

Estimated gross yields 206.3 150.7 114.1 165.4 109.8 73.17 60.73 11.79 --
48 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Table 20. Estimated gross yield, gross yield minus the 7-day, 10-year flow, and gross yield minus the Aquatic Base Flow of water 

availability for June, July, August, and September in the Pawcatuck Basin, southern Rhode Island and southeastern 

Connecticut.—Continued

[7Q10, 7-day, 10-year flow; ABF, Aquatic Base Flow; Mgal/d, million gallons per day; --, values at station less than zero and not used]

Subbasin

Estimated gross yield for August 

(Mgal/d) 

Estimated gross yield minus 7Q10 

for August (Mgal/d)

Estimated gross yield minus ABF 

for August (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Estimated Yields from Sand and Gravel Deposits

Chipuxet subbasin1 28.89 20.56 13.37 24.96 16.63 9.432 4.581 -- --

Usquepaug–Queen subbasin2 12.67 9.086 5.728 10.11 6.524 3.167 -- -- --

Beaver–Pasquiset subbasin3 12.05 8.251 5.418 9.580 5.783 2.950 1.329 -- --

Upper Wood subbasin4 22.98 12.80 10.67 18.32 8.144 6.010 7.640 -- --

Lower Wood subbasin5 16.01 10.99 7.915 11.55 6.531 3.454 4.134 -- --

Lower Pawcatuck subbasin5 29.06 19.95 14.37 20.97 11.85 6.269 7.502 -- --

Total estimated yields from 

sand and gravel deposits 

121.7 81.64 57.47 95.49 55.46 31.28 25.19 -- --

Estimated Yields from Till Deposits

Chipuxet subbasin1 6.285 4.473 2.908 5.429 3.618 2.052 0.997 -- --

Usquepaug–Queen subbasin2 5.177 3.711 2.340 4.131 2.665 1.293 -- -- --

Beaver–Pasquiset subbasin3 4.875 3.339 2.192 3.877 2.340 1.194 .538 -- --

Upper Wood subbasin4 18.93 10.55 8.788 15.09 6.708 4.950 6.293 -- --

Lower Wood subbasin5 6.403 4.396 3.165 4.619 2.612 1.381 1.653 -- --

Lower Pawcatuck subbasin5 22.16 15.21 10.95 15.99 9.038 4.780 5.721 -- --

Total estimated yields from till 

deposits 

63.83 41.68 30.34 49.14 26.98 15.65 15.20 -- --

Estimated gross yields 185.5 123.3 87.81 144.6 82.44 46.93 40.39 -- --
Water Availability 49

1Estimated gross yields based on base flow from the Chipuxet stream-gaging station, 1974 through 2000. 2Estimated gross yields based on base flow from the Usquepaug stream-gaging station, 1975 through 2000. 3Estimated gross yields based on base flow from the Beaver stream-gaging station, 1975 through 2000. 4Estimated gross yields based on base flow from the Arcadia stream-gaging station, 1964 through 1981 and 1983 through 2000. 5Estimated gross yields based on base flow from the Wood River Junction stream-gaging station, 1941 through 2000. 

Table 20. Estimated gross yield, gross yield minus the 7-day, 10-year flow, and gross yield minus the Aquatic Base Flow of water 

availability for June, July, August, and September in the Pawcatuck Basin, southern Rhode Island and southeastern 

Connecticut.—Continued

[7Q10, 7-day, 10-year flow; ABF, Aquatic Base Flow; Mgal/d, million gallons per day; --, values at station less than zero and not used]

Subbasin

Estimated gross yield for 

September (Mgal/d) 

Estimated gross yield minus 7Q10 

for September (Mgal/d)

Estimated gross yield minus ABF 

for September (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Estimated Yields from Sand and Gravel Deposits

Chipuxet subbasin1 20.82 17.00 12.22 16.89 13.06 8.283 -- -- --

Usquepaug–Queen subbasin2 11.63 7.824 5.375 9.073 5.262 2.813 -- -- --

Beaver–Pasquiset subbasin3 9.843 7.200 4.878 7.375 4.732 2.410 -- -- --

Upper Wood subbasin4 17.98 12.89 10.18 13.32 8.231 5.517 2.639 -- --

Lower Wood subbasin5 12.68 9.012 6.360 8.222 4.551 1.899 .805 -- --

Lower Pawcatuck subbasin5 23.02 16.36 11.54 14.92 8.259 3.447 1.461 -- --

Total estimated yields from 

sand and gravel deposits 

95.97 70.29 50.55 69.80 44.10 24.37 4.905 -- --

Estimated Yields from Till Deposits

Chipuxet subbasin1 4.530 3.698 2.658 3.674 2.842 1.802 -- -- --

Usquepaug–Queen subbasin2 4.752 3.196 2.195 3.706 2.149 1.149 -- -- --

Beaver–Pasquiset subbasin3 3.983 2.913 1.974 2.984 1.915 .975 -- -- --

Upper Wood subbasin4 14.81 10.62 8.383 10.97 6.780 4.545 2.174 -- --

Lower Wood subbasin5 5.072 3.604 2.543 5.161 3.579 2.539 .322 -- --

Lower Pawcatuck subbasin5 17.55 12.47 8.802 11.38 6.298 2.629 1.114 -- --

Total estimated yields from till 

deposits 

50.70 36.50 26.56 37.88 23.56 13.64 3.610 -- --

Estimated gross yields 146.7 106.8 77.11 107.7 67.66 38.01 8.515 -- --

Table 21. Estimated gross yield of water availability for June, July, August, and September in the Pawcatuck Basin, southern Rhode 

Island and southeastern Connecticut.

[7Q10, 7-day, 10-year; ABF, Aquatic Base Flow; Mgal/d, Million gallons per day; --, values at station less than zero and not used]

Subbasin

Estimated gross yield for June 

(Mgal/d)

Estimated gross yield minus 7Q10 

for June (Mgal/d)

Estimated gross yield minus ABF 

for June (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet subbasin1 69.20 45.78 32.85 64.41 41.00 28.06 39.61 16.19 3.257

Usquepaug–Queen subbasin2 44.80 25.68 21.03 41.20 22.07 17.42 26.50 7.383 2.735

Beaver–Pasquiset subbasin3 47.38 28.12 22.71 43.92 24.65 19.24 32.33 13.07 7.651

Upper Wood subbasin4 83.73 57.54 43.31 75.23 49.04 34.81 55.75 29.56 15.33

Lower Wood subbasin5 42.25 33.08 26.34 36.00 26.83 20.10 25.62 16.45 9.71

Lower Pawcatuck subbasin5 96.53 75.58 60.19 82.27 61.31 45.93 58.53 37.58 22.20

Total estimated yields 383.9 265.8 206.4 343.1 224.9 165.6 238.3 120.2 60.88
50 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

1Estimated gross yields based on base flow from the Chipuxet stream-gaging station, 1974 through 2000.

2Estimated gross yields based on base flow from the Usquepaug stream-gaging station, 1975 through 2000.

3Estimated gross yields based on base flow from the Beaver stream-gaging station, 1975 through 2000.

4Estimated gross yields based on base flow from the Arcadia stream-gaging station, 1964 through 1981 and 1983 through 2000.

5Estimated gross yields based on base flow from the Wood River Junction stream-gaging station, 1941 through 2000.

Table 21. Estimated gross yield of water availability for June, July, August, and September in the Pawcatuck Basin, southern Rhode 

Island and southeastern Connecticut.—Continued

[7Q10, 7-day, 10-year; ABF, Aquatic Base Flow; Mgal/d, Million gallons per day; --, values at station less than zero and not used]

Subbasin

Estimated gross yield for July 

(Mgal/d) 

Estimated gross yield minus 7Q10 

for July (Mgal/d)

Estimated gross yield minus ABF 

for July (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet subbasin1 43.56 24.28 18.15 38.77 19.49 13.36 13.96 -- --

Usquepaug–Queen subbasin2 21.00 15.96 10.85 17.40 12.34 7.242 2.706 -- --

Beaver–Pasquiset subbasin3 20.64 16.25 11.80 17.17 12.78 8.328 5.579 1.190 --

Upper Wood subbasin4 41.21 32.53 23.55 32.72 24.03 15.05 13.24 4.554 --

Lower Wood subbasin5 24.32 18.77 15.13 18.07 12.53 8.887 7.684 2.145 --

Lower Pawcatuck subbasin5 55.56 42.90 34.58 41.29 28.64 20.31 17.56 3.901 --

Total estimated yields 206.3 150.7 114.1 165.4 109.8 73.18 60.73 11.79 --

Subbasin

Estimated gross yield for August 

(Mgal/d) 

Estimated gross yield minus 7Q10 

for August (Mgal/d)

Estimated gross yield minus ABF 

for August (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet subbasin1 35.18 25.03 16.28 30.39 20.25 11.48 5.578 -- --

Usquepaug–Queen subbasin2 17.85 12.80 8.068 14.24 9.189 4.460 -- -- --

Beaver–Pasquiset subbasin3 16.92 11.59 7.610 13.46 8.123 4.144 1.867 -- --

Upper Wood subbasin4 41.91 23.35 19.46 33.41 14.85 10.96 13.93 -- --

Lower Wood subbasin5 22.41 15.39 11.08 16.17 9.143 4.835 5.787 -- --

Lower Pawcatuck subbasin5 51.22 35.16 25.32 36.96 20.89 11.05 13.22 -- --

Total estimated yields 185.5 123.3 87.82 144.6 82.44 46.93 40.38 -- --

Subbasin

Estimated gross yield for 

September

(Mgal/d) 

Estimated gross yield minus 7Q10 

for September (Mgal/d)

Estimated gross yield minus ABF 

for September (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet subbasin1 25.35 20.70 14.88 20.56 15.90 10.08 -- -- --

Usquepaug–Queen subbasin2 16.38 11.02 7.570 12.78 7.411 3.962 -- -- --

Beaver–Pasquiset subbasin3 13.83 10.11 6.852 10.36 6.647 3.385 -- -- --

Upper Wood subbasin4 32.79 23.51 18.56 24.29 15.01 10.06 4.813 -- --

Lower Wood subbasin5 17.75 12.62 8.903 13.38 8.130 4.438 1.127 -- --

Lower Pawcatuck subbasin5 40.57 28.83 20.34 26.30 14.56 6.076 2.575 -- --

Total estimated yields 146.7 106.8 77.10 107.7 67.66 38.00 8.515 -- --
Water Availability 51

0

5

10

15

20

25

30

35

40

45

50

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

0

5

10

15

20

25

30

35

40

45

50

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

WATER AVAILABILITY, MILLION GALLONS PER DAY

JUNE

JULY

AUGUST

SEPTEMBER

0

5

10

15

20

25

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

SUBBASINS OF THE PAWCATUCK BASIN

A.

B.

C.

EXPLANATION

Figure 14. Estimated water availability for June, July, August, and September from sand and gravel 

deposits for the subbasins in the Pawcatuck Basin, southern Rhode Island and southeastern 

Connecticut, based on the A, 50th percentile; B, 50th percentile minus the 7-day, 10-year flow criteria; 

and C, 50th percentile minus the Aquatic Base Flow criteria. 
52 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

0

5

10

15

20

25

30

35

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

0

5

10

15

20

25

30

35

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

WATER AVAILABILITY, MILLION GALLONS PER DAY

JUNE

JULY

AUGUST

SEPTEMBER

0

5

10

15

20

25

30

35

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

SUBBASINS OF THE PAWCATUCK BASIN

A.

B.

C.

EXPLANATION

Figure 15. Estimated water availability for June, July, August, and September from till deposits 

for the subbasins in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 

based on the A, 50th percentile; B, 50th percentile minus the 7-day, 10-year flow criteria; and 

C, 50th percentile minus the Aquatic Base Flow criteria.
Water Availability 53

0

10

20

30

40

50

60

70

80

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

0

10

20

30

40

50

60

70

80

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

WATER AVAILABILITY, MILLION GALLONS PER DAY 0

10

20

30

40

50

60

70

80

CHIPUXET USQUEPAUGQUEEN BEAVERPASQUISET UPPER WOOD LOWER WOOD LOWER

PAWCATUCK

SUBBASINS OF THE PAWCATUCK BASIN

JUNE

JULY

AUGUST

SEPTEMBER

EXPLANATION

B.

A.

C.

Figure 16. Estimated water availability for June, July, August, and September for the subbasins in the 

Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, based on the A, 50th 

percentile; B, 50th percentile minus the 7-day, 10-year flow criteria; and C, 50th percentile minus the 

Aquatic Base Flow criteria.
54 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Table 22. Average water withdrawals for June, July, August, and September in the subbasins in 

the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, 1995–99.

[Mgal/d, million gallons per day]

Subbasins Average water withdrawals 1995–99 (Mgal/d)

June July August September

Chipuxet subbasin 4.976 6.120 5.972 4.141

Usquepaug–Queen subbasin .833 1.144 1.421 .521

Beaver–Pasquiset subbasin .542 .695 .831 .388

Upper Wood subbasin .870 1.041 1.175 .702

Lower Wood subbasin .932 1.155 1.353 .709

Lower Pawcatuck subbasin 5.201 5.975 5.747 4.459

Basin total 13.35 16.13 16.50 10.92

. Table 23. Summary of water withdrawals to availability ratios for June, July, August, and September in the Pawcatuck Basin, southern 

Rhode Island and southeastern Connecticut.

[7Q10, 7-day, 10-year flow; ABF, Aquatic Base Flow; Mgal/d, million gallons per day; --, values at station less than zero and not used]

Subbasins

Ratio for June, estimated gross 

yield (Mgal/d) 

Ratio for June, estimated gross

yield minus 7Q10 (Mgal/d)

Ratio for June, estimated yield

minus ABF (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet subbasin1 0.072 0.109 0.151 0.077 0.121 0.177 0.126 0.307 1.528

Usquepaug–Queen subbasin2 .019 .032 .040 .020 .038 .048 .031 .113 .305

Beaver–Pasquiset subbasin3 .011 .019 .024 .012 .022 .028 .017 .041 .071

Upper Wood subbasin4 .010 .015 .020 .012 .018 .025 .016 .029 .057

Lower Wood subbasin5 .022 .028 .035 .026 .035 .046 .036 .057 .096

Lower Pawcatuck subbasin5 .054 .069 .086 .063 .085 .113 .089 .138 .234

Basin ratios 0.035 0.050 0.065 0.039 0.059 0.081 0.056 0.111 0.219

Subbasin

Ratio for July, estimated gross 

yield (Mgal/d) 

Ratio for July, estimated gross

yield minus 7Q10 (Mgal/d)

Ratio for July, estimated yield

minus ABF (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet subbasin1 0.140 0.252 0.337 0.158 0.314 0.458 0.438 -- --

Usquepaug–Queen subbasin2 .054 .072 .105 .066 .093 .158 .423 -- --

Beaver–Pasquiset subbasin3 .034 .043 .059 .040 .054 .083 .125 0.584 --

Upper Wood subbasin4 .025 .032 .044 .032 .043 .069 .079 .229 --

Lower Wood subbasin5 .047 .062 .076 .064 .092 .130 .150 .538 --

Lower Pawcatuck subbasin5 .108 .139 .173 .145 .209 .294 .340 1.532 --

Basin ratios 0.078 0.107 0.141 0.098 0.147 0.220 0.266 1.368 --
Water Availability 55

1Estimated gross yields based on base flow from the Chipuxet stream-gaging station, 1974 through 2000.

2Estimated gross yields based on base flow from the Usquepaug stream-gaging station, 1975 through 2000.

3Estimated gross yields based on base flow from the Beaver stream-gaging station, 1975 through 2000.

4Estimated gross yields based on base flow from the Arcadia stream-gaging station, 1964 through 1981 and 1983 through 2000.

5Estimated gross yields based on base flow from the Wood River Junction stream-gaging station, 1941 through 2000.

Table 23. Summary of water withdrawals to availability ratios for June, July, August, and September in the Pawcatuck Basin, southern 

Rhode Island and southeastern Connecticut.—Continued

[7Q10, 7-day, 10-year flow; ABF, Aquatic Base Flow; Mgal/d, million gallons per day; --, values at station less than zero and not used]

Subbasin

Ratio for August, estimated gross 

yield (Mgal/d) 

Ratio for August, estimated gross 

yield minus 7Q10 (Mgal/d)

Ratio for August, estimated yield 

minus ABF (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet subbasin1 0.170 0.239 0.367 0.197 0.295 0.520 1.071 -- --

Usquepaug–Queen subbasin2 .080 .111 .176 .100 .155 .319 -- -- --

Beaver–Pasquiset subbasin3 .049 .072 .109 .062 .102 .200 .445 -- --

Upper Wood subbasin4 .028 .050 .060 .035 .079 .107 .084 -- --

Lower Wood subbasin5 .060 .088 .122 .084 .148 .280 .234 -- --

Lower Pawcatuck subbasin5 .112 .163 .227 .155 .275 .520 .435 -- --

Basin ratios 0.089 0.134 0.188 0.114 0.200 0.352 0.409 -- --

Subbasin

Ratio for September, estimated 

gross yield (Mgal/d)

Ratio for September, estimated

gross yield minus 7Q10 (Mgal/d)

Ratio for September, estimated

yield minus ABF (Mgal/d)

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

Chipuxet subbasin1 0.163 0.200 0.278 0.201 0.260 0.411 -- -- --

Usquepaug–Queen subbasin2 .032 .047 .069 .041 .070 .131 -- -- --

Beaver–Pasquiset subbasin3 .028 .038 .057 .037 .058 .115 -- -- --

Upper Wood subbasin4 .021 .030 .038 .029 .047 .070 0.146 -- --

Lower Wood subbasin5 .040 .056 .080 .053 .087 .160 .629 -- --

Lower Pawcatuck subbasin5 .110 .155 .219 .170 .306 .734 1.732 -- --

Basin ratios 0.074 0.102 0.142 0.101 0.161 0.287 1.282 -- --
56 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

A.

CONNECTICU

T

RHODE ISLAND

0 1 2 MILES

0 1 2 KILOMETERS

71O55' 71O

30'

41O40'

41O20'

LOWER WOOD

UPPER WOOD

CHIPUXET

USQUEPAUG-QUEEN

LOWER PAWCATUCK

BEAVER - PASQUISET

JULY WATER WITHDRAWAL TO

WATER AVAILABLE RATIOS

0.314 Chipuxet

0.209 Lower Pawcatuck

0.093 Usquepaug-Queen

0.092 Lower Wood

0.054 Beaver-Pasquiset

0.043 Upper Wood

0.314

0.092

0.209

0.043

0.093

0.054

EXPLANATION

0.205 in area

upstream of

the Chipuxet

station

Figure 17. The water-withdrawal to water-availability ratio in A, July; B, August; and C, September for the subbasins 

in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, at the 50th percentile minus the 7-day, 

10-year flow criteria.
Water Availability 57

B.

CONNECTICU

T

RHODE ISLAND

0 1 2 MILES

0 1 2 KILOMETERS

71O55' 71O

30'

41O40'

41O20'

LOWER WOOD

UPPER WOOD

CHIPUXET

USQUEPAUG-QUEEN

LOWER PAWCATUCK

BEAVER - PASQUISET

AUGUST WATER WITHDRAWAL TO

WATER AVAILABLE RATIOS

0.295 Chipuxet

0.275 Lower Pawcatuck

0.155 Usquepaug-Queen

0.148 Lower Wood

0.102 Beaver-Pasquiset

0.079 Upper Wood

0.295

0.148

0.275

0.079

0.155

0.102

EXPLANATION

0.225 in area

upstream of

the Chipuxet

station

Figure 17—Continued. The water-withdrawal to water-availability ratio in A, July; B, August; and C, September for the 

subbasins in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, at the 50th percentile minus the 

7-day, 10-year flow criteria.
58 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99 CONNECTICU

T

RHODE ISLAND

0 1 2 MILES

0 1 2 KILOMETERS

71O55' 71O

30'

41O40'

41O20'

LOWER WOOD

UPPER WOOD

CHIPUXET

USQUEPAUG-QUEEN

LOWER PAWCATUCK

BEAVER - PASQUISET

SEPTEMBER WATER WITHDRAWAL

TO WATER AVAILABLE RATIOS

0.306 Lower Pawcatuck

0.260 Chipuxet

0.087 Lower Wood

0.070 Usquepaug-Queen

0.058 Beaver-Pasquiset

0.047 Upper Wood

0.260

0.087

0.306

0.047

0.070

0.058

EXPLANATION

0.166 in area

upstream of

the Chipuxet

station

C.

Figure 17—Continued. The water-withdrawal to water-availability ratio in A, July; B, August; and C, September for the 

subbasins in the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut, at the 50th percentile minus 

the 7-day, 10-year flow criteria.
Water Availability 59

In the Lower Wood subbasin, the estimated water 

availability for the gross yield at the 50th percentile ranged 

from 9.012 Mgal/d in September to 23.63 Mgal/d in June 

for the contributions from sand and gravel deposits, and 

ranged from 3.604 Mgal/d in September to 9.448 Mgal/d in 

June for the contributions from till deposits (table 20). The 

water availability in the subbasin at the 50th percentile for 

the gross yield ranged from 12.62 Mgal/d in September to 

33.08 Mgal/d in June, and by using the 7Q10 criteria, ranged 

from 8.130 Mgal/d in September to 26.83 Mgal/d in June 

(table 21).The average water withdrawals for the Lower 

Wood subbasin ranged from 0.709 Mgal/d in September to 

1.353 Mgal/d in August for the study period (table 22). The 

results for the ratios for the gross-yield scenario at the 50th 

percentile ranged from 0.028 in June to 0.088 in August, and by 

using the 7Q10 criteria, the ratios ranged from 0.035 in June to 

0.148 in August (table 23).

In the Lower Pawcatuck subbasin, the estimated 

water availability for the gross yield at the 50th percentile 

ranged from 16.36 Mgal/d in September to 42.88 Mgal/d 

in June for the contributions from sand and gravel deposits, 

and ranged from 12.47 Mgal/d in September to 32.70 Mgal/d 

in June for the contributions from till deposits (table 20). 

The water availability in the subbasin at the 50th percentile 

for the gross yield ranged from 28.83 Mgal/d in September to 

75.58 Mgal/d in June, and by using the 7Q10 criteria, ranged 

from 14.56 Mgal/d in September to 61.31 Mgal/d in June 

(table 21).The average water withdrawals for the Lower 

Pawcatuck subbasin ranged from 4.459 Mgal/d in September to 

5.975 Mgal/d in July for the study period (table 22). The results 

for the ratios for the gross-yield scenario at the 50th percentile 

ranged from 0.069 in June to 0.163 in August, and by using the 

7Q10 criteria, the ratios ranged from 0.085 in June to 0.306 in 

September (table 23).

The Chipuxet subbasin resulted as the area where most of 

the withdrawals were present and where the water withdrawals 

were approaching or passing the estimated water available, 

resulting in higher ratios. Therefore, further analysis was 

conducted on the water withdrawals and availability in the area 

upstream of the Chipuxet stream-gaging station. The summer 

water withdrawals for the study period in this area ranged 

from 0.534 Mgal/d in September to 0.924 Mgal/d in August 

(table 24). The results for the ratios for the gross-yield scenario 

at the 50th percentile ranged from 0.061 in June to 0.182 in 

August, and by using the 7Q10 criteria, the ratios ranged from 

0.068 in June to 0.225 in August (table 24). 

Streamflow Depletion

The streamflow-depletion program (STRMDEPL) 

developed by Barlow (2000) is used to examine the depletion of 

the streams from wells near the streams. The program is based 

on methods and equations from Jenkins (1968); the program is 

for wells where the sediments along the streambank are 

impervious. The Jenkins method was used to assess what effect 

the Kingston Water District wells 1 and 2 had on the Chipuxet 

River, and to assess the effect the Westerly Water Department 

withdrawals at well field 1, well field 2, and well 3 had on the 

Pawcatuck River. The depletions of Chipuxet River flows by 

Kingston Water District wells 1 and 2 were estimated with 

STRMDEPL by using daily withdrawals from the Chipuxet 

aquifer for January 1, 1995, through December 31, 1999. The 

depletions of the Pawcatuck River by the Westerly Water 

Department’s well fields 1 and 2 and well 3 were also estimated 

by using daily withdrawals for October 1, 1997, through 

September 30, 1999 (table 25). The details of the well distances 

to the streams, transmissivities, diffusivities, and comparisons 

to the data for the station near the well are presented in table 25. 

The streamflow depletions for Kingston well 1 and 2, Westerly 

well fields 1 and 2, and well 3 were approximately 96, 98, 101, 

98, and 100 percent of the average daily water withdrawals for 

the periods specified. 

Because the summer of 1999 was drier than other summers 

during the study period, further analysis was completed for the 

streamflow depletions of the Kingston and Westerly withdrawal 

wells. In July of 1999, streamflow depletions for Kingston 

well 1 and 2, Westerly well fields 1 and 2, and well 3 were 

approximately 101, 99, 101, 98, and 99 percent of the average 

daily water withdrawals for the periods specified (table 26). 

Information and results for the well withdrawals, streamflow 

depletion for June, July, August, and September are presented 

in table 26. For comparison to the withdrawals and streamflow 

depletions, streamflows at the Chipuxet and Westerly streamgaging stations were calculated during 1999 and are presented 

in table 27. In addition, a simulation was done to assess the 

streamflow depletion from continuous water withdrawals. In 

the simulation, public well and well fields were simulated at a 

constant pumping rate, based on the 1999 summer average for 

each withdrawal, over a period of 180 days. As a result, the percentages of streamflow depletion were 86 and 95 after 30 days 

of continuous pumping at Kingston wells 1 and 2, respectively, 

as shown in figure 18 and table 28. The percentages of streamflow depletion were 93, 96, and 98 percent after 30 days of 

pumping at Westerly well fields 1 and 2, and well 3, respectively, as shown in figure 19 and table 28. 

Water Budget

The Pawcatuck Basin water budget encompasses the 

hydrologic cycle and the water-use components, inflow and 

outflow to the system. For a water budget, inflow minus outflow 

equals the change in storage in the basin. For this report, longterm water budget was calculated where inflow equals outflow 

in the system. The change in water storage from surface-water 
60 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

bodies and from ground-water aquifers is considered to be 

negligible in this water budget. Inflows to the basin include 

precipitation, streamflow from upstream subbasins, groundwater inflow, and return flow (septic systems, RIPDES, and 

wastewater-treatment facilities). Outflows from the basin 

include evapotranspiration, streamflow out of the subbasins, 

water withdrawals (public supplies and self-supplied domestic, 

commercial, industrial, and agricultural), and ground-water 

underflow. The water budget components are summarized in 

table 29. 

Table 24. Monthly water withdrawals and withdrawal to availability ratios for the Chipuxet stream-gaging station in the Pawcatuck 

Basin, southern Rhode Island and southeastern Connecticut.

[7Q10, 7-day, 10-year flow; ABF, Aquatic Base Flow, based on the median of the August monthly means; Mgal/d, Million gallons per day; --, values at station 

less than zero and not used]

Month

Withdrawals 

upstream of 

Chipuxet station 

(Mgal/d)

Ratio of water withdrawals to availability at the Chipuxet stream-gaging station

 Estimated gross yield Estimated gross yield minus 7Q10 Estimated gross yield minus ABF

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

75th

percentile

50th

percentile

25th

percentile

June 0.569 0.041 0.061 0.085 0.044 0.068 0.100 0.071 0.173 0.862

July .808 .091 .164 .220 .103 .205 .298 .286 -- --

August .924 .130 .182 .280 .150 .225 .397 .818 -- --

September .534 .104 .127 .177 .128 .166 .261 -- -- --

1Average transmissivity from Johnston and Dickerman (1985). Average streamflow depletion from daily withdrawals from Kingston wells near the Chipuxet 

River, 1995 through 1999.

2Average transmissivity from Gonthier and others (1974). Average streamflow depletion from daily withdrawals from Westerly wells near the Pawcatuck 

River, November 1997 through September 1999.

Table 25. Average distance, transmissivity, diffusivity, pumping rate, streamflow-depletion rates, and streamflow of rivers from the 

Kingston and Westerly public-supply wells and well fields used in Jenkins analysis in the Pawcatuck Basin in southern Rhode Island.

[Reference letter: Identifier used in figure 4. To convert to million gallons per day, multiply cubic feet per second by 0.646577. d, day; ft, foot; ft2/d, square foot 

per day; ft2/s, square foot per second; ft3/s, cubic foot per second; <, actual value is less than value shown]

Selected public-water

supplier

Public-supply 

wells and (or) 

well fields

Reference

letter

Average

distance

to river

(ft)

Average 

transmissivity

(ft2

/d) Diffusivity

(ft2/s)

Average

pumping

rate

(ft3

/s)

Average

streamflowdepletion

rate

(ft3/s)

 Average

streamflow

(ft3/s)

Lag

time

(d)

Kingston Water District1 Well 1 A 370 21,200 0.8681 0.2127 0.2044 21.44 <1

Well 2 B 120 21,200 .8681 .4748 .4738 21.44 <1

Westerly Water 

Department2

Well field 1 

Well 1A

Well 1B

Well 1D

--

M

N

O

256 

396

133

240

40,000 1.6543 1.3530 1.3674 612.04 <1

Well field 2

Well 2A

Well 2B

Well 2D

--

P

Q

R

161 

215

164

105

40,000 1.6543 1.668 1.668 612.04 <1

Well 3 S 83 40,000 1.6543 .7057 .7070 612.04 <1
Water Availability 61

Table 26. Average pumping rate and streamflow depletion from selected Kingston and Westerly public-supply wells used in Jenkins 

analysis during June, July, August, and September of 1999 in the Pawcatuck Basin, southern Rhode Island.

[Jenkins analysis from Jenkins (1968). Mgal/d, million gallons per day]

Selected

public wells

and well fields

June 1999 (Mgal/d) July 1999 (Mgal/d) August 1999 (Mgal/d) September 1999 (Mgal/d)

Average

pumping

rate

Average

streamflowdepletion

rate 

Average

pumping

rate

Average

streamflowdepletion

rate 

Average

pumping

rate

Average

streamflowdepletion

rate 

Average

pumping

rate

Average

streamflowdepletion

rate 

Kingston Water District

Well 1 0.239 0.230 0.187 0.188 0.187 0.188 0.123 0.134

Well 2 .385 .374 .391 .385 .314 .317 .295 .296

Total 0.624 0.604 0.578 0.574 0.501 0.506 0.419 0.431

Westerly Water Department

Well field 1 1.265 1.239 1.071 1.078 1.028 1.034 0.961 0.978

Well field 2 1.468 1.430 1.641 1.606 1.138 1.155 1.053 1.042

Well 3 .535 .533 .541 .537 .557 .556 .379 .387

Total 3.268 3.201 3.252 3.222 2.723 2.745 2.393 2.407

Table 27. Average streamflow at the Chipuxet River and Pawcatuck River stream-gaging stations during June, July, August, and 

September of 1999 in the Pawcatuck Basin, southern Rhode Island.

[Mgal/d, million gallons per day]

Station

Average streamflow (Mgal/d)

June

1999 

July

1999 

August

1999 

September

1999 

Chipuxet River at West Kingston, RI 7.27 2.84 1.61 3.94

Pawcatuck River at Westerly, RI 148.1 71.83 46.47 161.5

The average precipitation at Kingston, RI, was calculated 

for the period of record reported in the water budget at the index 

stations. For the Chipuxet subbasin, an average precipitation 

of 51.26 in/yr for 1974 through 2000 was applied to the 

subbasin by using 2.442 Mgal/d/mi2. For the Usquepaug–

Queen and Beaver–Pasquiset subbasins, an average 

precipitation of 51.61 in/yr for 1975 through 2000 was applied 

to the subbasin by using 2.458 Mgal/d/mi2. For the Upper 

Wood subbasin, an average precipitation of 50.34 in/yr for 1964 

through 1981 and 1983 through 2000 was applied to the 

subbasin by using 2.399 Mgal/d/mi2. For the Lower Wood and 

Lower Pawcatuck subbasins, an average precipitation of 48.08 

in/yr for 1941 through 2000 was applied to the subbasins by 

using 2.287 Mgal/d/mi2. The Beaver–Pasquiset, Lower Wood, 

and Lower Pawcatuck subbasins have surface-water inflow 

from subbasins upstream. Estimating ground-water inflow was 

considered negligible for this study because of data availability. 

Return flow includes the average disposal of water from septic 

systems from 1995 through 1999, RIPDES, and wastewatertreatment facilities in the subbasins of the Pawcatuck Basin. 

Evapotranspiration was estimated based on the difference 

between the precipitation and outflow at the confluence, which 

was based on the mean annual flow at the index stream-gaging 

station. The outflow of streamflow from each subbasin was 

estimated by using the sum of the inflows minus the 

withdrawals minus evapotranspiration. 
62 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

0 20 40 60 80 100 120 140 160 180

Kingston Water District Well 1

Kingston Water District Well 2

DAYS OF CONTINUOUS PUMPING

DECIMAL PERCENT

Figure 18. Decimal percentage of streamflow depletion simulation during 180 

days of continuous pumping for Kingston Water District wells 1 and 2, Pawcatuck 

Basin, southern Rhode Island. 

Table 28. Pumping rate for 180 days and percent streamflow depletion divided by pumping rate from selected public-supply withdrawal 

wells for the Kingston Water District and Westerly Water Department used in Jenkins analysis in 1999 in the Pawcatuck Basin, southern 

Rhode Island.

[Jenkins analysis from Jenkins (1968). Pumping rate: Based on the average daily pumping rate for June–September 1999. ft3/s, cubic foot per second; Mgal/d, 

million gallons per day] 

Selected wells and 

well fields

Pumping rate Percent streamflow depletion of the water withdrawals

Mgal/d ft3/s 10 days 20 days 30 days 40 days 50 days 60 days 70 days 80 days 90 days

Kingston Water District

Well 1 0.184 0.285 76 83 86 88 89 90 91 91 92

Well 2 .347 .536 92 94 95 96 97 97 97 97 97

Westerly Water Department

well field 1 1.082 1.673 88 91 93 94 95 95 95 96 96

well field 2 1.328 2.054 92 95 96 96 97 97 97 97 97

Well 3 .505 .781 96 97 98 98 98 98 99 99 99
Water Availability 63

0.60

0.65

0.70

0.75

0.80

0.85

0.90

0.95

1.00

0 20 40 60 80 100 120 140 160 180

Westerly Water Department Well Field 1

Westerly Water Department Well Field 2

Westerly Water Department Well 3

DAYS OF CONTINUOUS PUMPING

DECIMAL PERCENT

Figure 19. Decimal percentage of streamflow depletion simulation during 180 

days of continuous pumping for Westerly Water Department well fields 1 and 2, 

and well 3, Pawcatuck Basin, southern Rhode Island and southeastern 

Connecticut. 

For the water budget, it was assumed that inflow equals 

outflow for the subbasins. The total water budget for the 

Chipuxet subbasin was 90.64 Mgal/d. The estimated 

percentages of inflows from precipitation and water return flow 

were 99 and 1 percent, and the estimated percentages of 

outflows from evapotranspiration, streamflow, and water 

withdrawals were 44, 52, and 4 percent in the Chipuxet 

subbasin, respectively. The total water budget for the 

Usquepaug–Queen subbasin was 89.06 Mgal/d. The estimated 

percentages of inflows from precipitation and water return flow 

were 99 and 1 percent, and the estimated percentages of 

outflows from evapotranspiration, streamflow, and water 

withdrawals were 44, 55, and 1 percent in the Usquepaug–

Queen subbasin, respectively. The total water budget for the 

Beaver–Pasquiset subbasin was 152.1 Mgal/d. The estimated 

percentages of inflows from precipitation, streamflow from 

upland subbasins, and water return flow were 36, 63, and 1 

percent, and the estimated percentages of outflows from 

evapotranspiration, streamflow, and water withdrawals were 

13, 86, and 1 percent in the Beaver–Pasquiset subbasin, 

respectively. The total water budget for the Upper Wood 

subbasin was 175.5 Mgal/d. The estimated percentages of 

inflows from precipitation and water return flow were 99 and 1 

percent, and the estimated percentages of outflows from 

evapotranspiration, streamflow, and estimated percentages of 

water withdrawals were 41, 58, and 1 percent in the Upper 

Wood subbasin, respectively. The total water budget for the 

Lower Wood subbasin was 317.9 Mgal/d. The estimated 

percentages of inflows from precipitation, streamflow from 

upland subbasins, and water return flow were 26, 73, and 1 

percent, and the estimated percentages of outflows from 

evapotranspiration, streamflow, and water withdrawals were

12, 88, and 0 percent in the Lower Wood subbasin, respectively. 

The total water budget for the Lower Pawcatuck subbasin was 

507.3 Mgal/d. The estimated percentages of inflows from 

precipitation, streamflow from upland subbasins, and water 

return flow were 44, 55, and 1 percent, and the estimated 

percentages of outflows from evapotranspiration, streamflow, 

and estimated percentages of water withdrawals were 20, 79, 

and 1 percent in the Lower Pawcatuck subbasin, respectively. 
64 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

1 Based on average precipitation (51.26 in/yr) at Kingston, RI, 1974–2000.

2 Based on average precipitation (51.61 in/yr) at Kingston, RI, 1975–2000.

3 Based on average precipitation (50.34 in/yr) at Kingston, RI, 1964–81 and 1983–2000.

4 Based on average precipitation (48.02 in/yr) at Kingston, RI, 1941–2000. 

5 Return flow based on the total return flow from septic, RIPDES, and wastewater-treatment facilities, in the subbasins of the Pawcatuck Basin, 

1995–99. 

6 Evapotranspiration based on the difference between the average precipitation at Kingston, RI, and average monthly flow at the index stream-gaging station 

for the subbasin.

7 Based on average monthly flow per unit area (1.371 Mgal/d/mi2) at the stream-gaging station Chipuxet River at West Kingston, RI, 1974–2000.

8 Based on average monthly flow per unit area (1.374 Mgal/d/mi2) at the stream-gaging station Usquepaug River near Usquepaug, RI, 1975–2000. 

9 Based on average monthly flow per unit area (1.550 Mgal/d/mi2) at the stream-gaging station Beaver River near Usquepaug, RI, 1975–2000. 

10 Based on average monthly flow per unit area (1.405 Mgal/d/mi2) at the stream-gaging station Wood River near Arcadia, RI, 1964–81 and 1983–2000. 

11 Based on average monthly flow per unit area (1.263 Mgal/d/mi2) at the stream-gaging station Pawcatuck River at Wood River Junction, RI, 

1941–2000. 

12 Based on the sum of the inflows minus withdrawals and evapotranspiration.

13 Water-withdrawal types include domestic, commercial, industrial, and agricultural withdrawals by users served by public- and self-supplied water in the 

subbasins of the Pawcatuck Basin, 1995–99.

Table 29. Average water budget by subbasin for the Pawcatuck Basin, southern Rhode Island and southeastern Connecticut.

[RIPDES, Rhode Island Pollution Discharge Elimination System; in/yr, inches per year; Mgal/d, million gallons per day; Mgal/d/mi

2, million gallons per day per 

square mile; mi2, square miles; --, not applicable]

Water-budget component

Rate of flow (Mgal/d)

Chipuxet

subbasin

Usquepaug–

Queen

subbasin

Beaver–

Pasquiset

subbasin

Upper

Wood

subbasin

Lower

Wood

subbasin

Lower

Pawcatuck

subbasin

Pawcatuck

Basin

Estimated Inflow

Precipitation 190.09 288.74 255.31 3175.0 483.26 4222.8 715.2

Streamflow from upstream subbasins -- -- 96.18 -- 233.5 279.8 --

Ground-water inflow -- -- -- -- -- -- --

Return flow5 .549 .316 .599 .542 1.109 4.740 7.855

Total inflow 90.64 89.06 152.1 175.5 317.9 507.3 723.1

Estimated Outflow

Evapotranspiration6 739.51 839.13 920.43 1072.46 1137.27 1199.70 308.5

Streamflow12 46.92 49.26 131.2 102.3 279.8 403.3 403.3

Water withdrawals13 4.212 .674 .463 .779 .819 4.303 11.25

Ground-water underflow -- -- -- -- -- -- --

Total outflow 90.64 89.06 152.1 175.5 317.9 507.3 723.1

Streamflow and Drainage Area

Streamflow per square mile (Mgal/d/mi2) 1.270 1.364 1.374 1.402 1.365 1.334 1.334

Total drainage area at outlet (mi2) 36.93 36.10 95.50 72.98 204.9 302.4 302.4
Summary 65

Summary

 The Pawcatuck Basin (302 square miles) is in southern 

Rhode Island (245.3 square miles) and southeastern 

Connecticut (57.12 square miles). In 1988, the Pawcatuck Basin 

was defined as a sole-source aquifer for 14 towns in southern 

Rhode Island and 4 towns in southeastern Connecticut for 

public-water suppliers and self-supplied populations. 

From the 1990 population census to the 2000 population 

census, population growth of southern Rhode Island ranged 

from a 6.3 percent increase in Westerly to a 35 percent increase 

in Richmond. During the study period, from 1995 through 

1999, the estimated population growth was highest in this same 

region, ranging from a 3-percent increase in Hopkinton and 

Westerly to a 10-percent increase in Richmond. Town 

populations also increased in the basin, and withdrawals 

increased from the ground-water system (sand and gravel 

deposits, ground-water reservoirs, and till deposits). During the 

drought of 1999, a rain deficiency resulted in ground-water 

levels and streamflows dropping below the long-term averages 

throughout Rhode Island. Consequently, the State became 

increasingly concerned about water availability, and further 

investigation was needed to assess water use and availability 

throughout Rhode Island. 

The U.S. Geological Survey, in cooperation with the 

Rhode Island Water Resources Board, began a series of wateruse and availability projects to better understand the relations 

between the water-use components and the components of the 

hydrologic cycle (predominantly surface and ground water) 

during periods of little to no recharge. One of the first areas of 

concern in this assessment was the Pawcatuck Basin because 

ground water is the principal water source for public suppliers 

and domestic users in the basin. 

This report assesses water use and availability in the 

Pawcatuck Basin and in its six ground-water subbasins for 

periods of little to no recharge. Water-use data were collected 

by ground-water subbasins for the towns and systems (supply 

and disposal) in the basin. The New England Water-Use Data 

System was used to organize and retrieve the water withdrawals 

and discharges for different kinds of water use during the study 

period. The report presents the water availability calculated for 

the six subbasins by a method of determining ground-water 

discharge during streamflow-recession periods in the summer. 

To assess the streamflow and ground-water interactions, a 

streamflow-depletion program was run for five of the publicsupply wells and well fields that are near the streams. A basin 

water budget is also presented that summarizes the components 

of the hydrologic cycle on the basis of the long-term period of 

record and selected water-use components for the study period.

The five major water suppliers in the basin withdrew an 

average of 6.768 million gallons per day (Mgal/d) from the 

aquifers in the subbasins during the study period. The estimated 

water withdrawals from minor suppliers during the study period 

were 0.099 Mgal/d. Self-supplied domestic, industrial, 

commercial, and agricultural withdrawals from the basin 

averaged 4.386 Mgal/d. Public-supply and self-supplied 

domestic, commercial, and industrial withdrawals in the basin 

were from ground water. Agricultural withdrawals for irrigation 

were assumed to be from surface water and ground water, based 

on previously published studies. Water use in the basin 

averaged 7.401 Mgal/d from 1995 through 1999. The average 

return flow in the basin was 7.855 Mgal/d, which includes 

effluent from permitted facilities and self-disposed water users.

The computerized PART program, a hydrographseparation application, was used for data at selected index 

stream-gaging stations to determine water availability based on 

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

base flow minus the 7-day, 10-year low-flow (7Q10) criteria at 

the index station, and the base flow minus the Aquatic Base 

Flow (ABF) criteria at the index station. Selected index stations 

for the Chipuxet subbasin, Usquepaug–Queen subbasin, 

Beaver–Pasquiset subbasin, and Upper Wood subbasin were 

the Chipuxet River at West Kingston (station 01117350), 

Usquepaug River near Usquepaug (station 01117420), Beaver 

River near Usquepaug (station 01117468), and Wood River 

near Arcadia (station 01117800), respectively. The Pawcatuck 

River at Wood River Junction stream-gaging station 

(01117500) was used as the index station for the Lower Wood 

and Lower Pawcatuck subbasins. During the summer, portions 

of the ground water drains out of the Pawcatuck Basin in the 

Chipuxet and Usquepaug–Queen subbasins. The differences in 

the surface and subsurface drainage areas in the summer have 

been applied to the water availability calculated at the streamgaging stations and subbasins.
66 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Contributions of base flow from surficial deposits, till, and 

stratified sand and gravel for the index stations are based on 

previous work by the U.S. Geological Survey. The base-flow 

contributions from sand and gravel deposits at the index stations 

were 67 percent at the Chipuxet stream-gaging station, 71 

percent at the Usquepaug and Wood River Junction streamgaging stations, 52 percent at the Beaver stream-gaging station, 

and 57 percent at the Arcadia stream-gaging station. The baseflow contributions from till deposits at the index stations were 

33 percent at the Chipuxet stream-gaging station, 29 percent at 

the Usquepaug and Wood River Junction stream-gaging 

stations, 48 percent at the Beaver stream-gaging station, and 43 

percent at the Arcadia stream-gaging station. The two 

contributions for June, July, August, and September were 

applied to the percentage of surficial deposits at each index 

station, converted into a per unit area rate for the till areas and 

sand and gravel areas in the subbasins. The scenarios used to 

estimate the gross yield of base flow, as well as subtracting out 

the two low-flow criteria resulted in various water-availability 

values at each index station, which were then present in the 

subbasin after applying the per unit area rates from the index 

station. The results at the Chipuxet and Arcadia stream-gaging 

station were lowest in September at the 75th and 25th 

percentiles, while August flows were lowest for the summer at 

the 50th percentile. For the other three index stations, 

September flows were the lowest for the summer. Wateravailability estimates and water-withdrawal to availability 

ratios were calculated for each subbasin. The cumulative 

withdrawals from upstream subbasins have not been accounted 

for in the water-availability calculations for the downstream 

subbasins. 

Because water withdrawals and use are greater during the 

summer than other times in the year, water availability in June, 

July, August, and September was assessed and compared to the 

water withdrawals in the basin and subbasins. The average 

water withdrawals for the Pawcatuck Basin ranged from 

10.92 Mgal/d in September to 16.50 Mgal/d in August for the 

study period. The water availability in the basin at the 50th 

percentile for the gross yield ranged from 106.8 Mgal/d in 

September to 265.8 Mgal/d in June, and by using the 7Q10 

scenario, water availability in the basin ranged from 

67.66 Mgal/d in September to 224.9 Mgal/d in June.

The water withdrawals to availability ratios were 

calculated for June, July, August, and September as an indicator 

of net availability of water in the basin and subbasins. The 

closer the ratio is to one, the closer the withdrawals are to the 

estimated water available. The ratios were calculated by using 

the water-availability scenarios at the 75th, 50th, and 25th 

percentiles for the subbasins and were based on total water 

available from base-flow contributions from till deposits and 

sand and gravel deposits in the subbasins. 

The withdrawals in August for the study period were 

higher than in the other summer months, and the water 

withdrawal-to-availability ratio was closer to one in the 

Pawcatuck Basin. The ratio at the 50th percentile for the basin 

was 0.134 by using the gross-yield scenario, and 0.200 for the 

base flow minus the 7Q10 criteria at the index station. The 

Chipuxet subbasin had the highest water withdrawal-toavailability ratios in all of the selected scenarios and months. 

The results in the subbasin for the ratios in July at the 50th 

percentile were 0.252 for the gross-yield scenario and 0.314 for 

the base flow minus the 7Q10 flow at the index station. 

The Chipuxet subbasin resulted as the area where most of 

the withdrawals were present and where the water withdrawals 

were approaching or passing the estimated water available, 

resulting in higher ratios. Therefore, further analysis was 

conducted on the water withdrawals and availability in the area 

upstream of the Chipuxet stream-gaging station. The summer 

water withdrawals for the study period in this area ranged from 

0.534 Mgal/d in September to 0.924 Mgal/d in August. The 

results for the ratios in August at the 50th percentile were 0.182 

for the gross yield scenario and 0.225 for the base flow minus 

the 7Q10 criteria at the station. 

The depletions of the Chipuxet River flows by Kingston 

Water District wells 1 and 2 were estimated with the program 

STRMDEPL by using daily withdrawals from the Chipuxet 

aquifer for the period January 1, 1995 through December 31, 

1999. The depletions of the Pawcatuck River by the Westerly 

Water Department’s well field 1 and 2 and well 3 were also 

estimated by using daily withdrawals for the period October 1, 

1997 through September 30, 1999. The streamflow depletions 

for Kingston well 1 and 2, Westerly well fields 1 and 2, and well 

3 were approximately 96, 98, 101, 98, and 100 percent, 

respectively, of the average daily water withdrawals for the 

periods specified. To present the effects of streamflow 

depletion from continuous water withdrawals, public well and 

well fields were simulated at a constant pumping rate, based on 

the 1999 summer average for each withdrawal, over a period of 

180 days. As a result, the streamflow depletion was 86, 95, 93, 

96, and 98 percent at 30 days for the Kingston well 1 and 2, 

Westerly well fields 1 and 2, and well 3, respectively. 

A long-term hydrologic budget was calculated for the 

Pawcatuck Basin to identify and assess the basin and subbasin 

inflow and outflows. The water withdrawals and return flows 

used in the budget were from the period of study, 1995 through 

1999. For the hydrologic budget, it was assumed that inflow 

equals outflow, which resulted in 723.1 Mgal/d in the basin. 

The estimated percentages of inflow from precipitation and 

return flow were 99 and 1 percent in the basin, respectively. The 

estimated percentages of outflow from evapotranspiration, 

streamflow, and water withdrawals were 43, 56, and 1 percent 

in the basin, respectively.
References Cited 67

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Glossary 71

Glossary

7-day, 10-year 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) 

Aquatic Base Flow (ABF): Median flow during the month of 

August established by the U.S. Fish and Wildlife Service and 

considered adequate flow to protect indigenous aquatic fauna 

throughout the year. It can be calculated as long as there is: 

“USGS 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 Service, 1981).

Base flow: Streamflow from ground-water discharge.

Commercial water use: Water used 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 of 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.

Distribution: The conveyance of water from a point of 

withdrawal or purification system to a user or other water 

customer.

Domestic water use: Water for household purposes, such as 

drinking, food preparation, bathing, washing, clothes and 

dishes, flushing toilets, and watering lawns and gardens. 

Households include single and multi-family dwellings. Also 

called residential water use. The water may be obtained from a 

public water supply or may be self supplied.

Industrial water use: Water used 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; where the two-digit Standard Industrial 

Classification codes range is 20–39. The water may be obtained 

from a public water supply or may be self supplied. 

Interbasin transfers: Conveyance of water across a drainage 

or river-basin divide.

Interconnections: Links between water-supply districts to 

convey water. These connections can be for wholesale 

distributions or used as water-supply backups. 

Irrigation water use: The artificial application of water on 

lands to assist in the growth of crops or pasture including in 

greenhouses. Irrigation water use may also include application 

of water to maintain vegetative growth in recreational lands 

such as parks and golf courses, including water used for frost 

and freeze protection of crops.

Major water supplier: A public or private system that 

withdraws and distributes water to customers or other suppliers 

for use.

Major user: In Rhode Island, it is defined as a customer that 

uses more than 3 million gallons of water per year.

Minor Civil Division (MCD): A term used by the U.S. Census 

Bureau, general equivalent to a city or town.

Minor water suppliers: Water withdrawn to supply a sitespecific public population, for example, nursing homes, 

condominium complexes, and mobile home parks. 

Non-account water use: The difference between the metered 

(or reported) supply and the metered (or reported) use for a 

specific period of time, which includes water used for fire 

fighting. It comprises authorized and unauthorized water uses. 
72 Estimated Water Use and Availability in the Pawcatuck Basin, Southern Rhode Island and Southeastern Conn., 1995–99

Outfall: Refers to the outlet or structure through which effluent 

is finally discharged into the environment.

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; 1998) to determine the mean rate of ground-water 

discharge.

Public wastewater system: Wastewater collected from users 

or groups of users, conveyed to a wastewater-treatment 

plant, and then released as return flow into the hydrologic 

environment or sent back to users as reclaimed wastewater.

Public water system: Water withdrawn by public and private 

water systems, and then delivered to users or groups of users. 

Public water systems provide water for a variety of uses, such 

as domestic, commercial, industrial, agricultural, and public 

water use.

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: Water return flow from public and 

private wastewater-collection systems.

Public-supplied water: Water distributed to domestic, 

industrial, commercial, agricultural, or other customers by a 

public or private water-supply system.

Return flow: Water that is returned to surface or ground water 

after use or wastewater treatment, and 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. 

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-supplied water: Water withdrawn from a ground- or 

surface-water source by a user and not obtained from a public 

or private 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 from a discharge pipe to 

a river or lake.

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, including 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 other 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 hydrologic system for use, including public-water 

supply, industry, commercial, domestic, irrigation, livestock, 

and thermoelectric power generation water uses.