Publications—Scientific Investigations Report 2006–5154

Estimated Water Use and Availability in the Pawtuxet and Quinebaug River Basins, Rhode Island, 1995–99

Prepared in cooperation with the Rhode Island Water Resources Board

By Emily C. Wild, and Mark T. Nimiroski

U.S. Geological Survey Scientific Investigations Report 2006–5154


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Abstract

Water availability became a concern in Rhode Island during a drought in 1999, and an investigation was needed to assess demands on the hydrologic system from withdrawals during periods of little to no precipitation. The low water levels during the drought prompted the U.S. Geological Survey and the Rhode Island Water Resources Board to begin a series of studies on water use and availability in each drainage area in Rhode Island for 1995–99. The study area for this report, which includes the Pawtuxet River Basin in central Rhode Island (231.6 square miles) and the Quinebaug River Basin in western Rhode Island (60.97 square miles), was delineated as the surface-water drainage areas of these basins.

During the study period from 1995 through 1999, two major water suppliers withdrew an average of 71.86 million gallons per day (Mgal/d) from the Pawtuxet River Basin; of this amount, about 35.98 Mgal/d of potable water were exported to other basins in Rhode Island. The estimated water withdrawals from minor water suppliers were 0.026 Mgal/d in the Pawtuxet River Basin and 0.003 Mgal/d in the Quinebaug River Basin. Total self-supply withdrawals were 2.173 Mgal/d in the Pawtuxet River Basin and 0.360 Mgal/d in the Quinebaug River Basin, which has no public water supply. Total water use averaged 18.07 Mgal/d in the Pawtuxet River Basin and 0.363 Mgal/d in the Quinebaug River Basin. Total return flow in the Pawtuxet River Basin was 30.64 Mgal/d, which included about 12.28 Mgal/d that were imported from other basins in Rhode Island. Total return flow was 0.283 Mgal/d in the Quinebaug River Basin.

During times of little to no recharge in the form of precipitation, the surface- and ground-water flows are from storage primarily in the stratified sand and gravel deposits; water also flows through the till deposits, but at a slower rate. The ground water discharging to the streams during times of little to no recharge from precipitation is referred to as base flow. The PART program, a computerized hydrograph-separation application, was used to analyze the data collected at two selected index stream-gaging stations to determine water availability on the basis of the 75th, 50th, and 25th percentiles of the total base flow; the base flow for the 7-day, 10-year low-flow scenario; and the base flow for the Aquatic Base Flow scenario for both stations. The index stream-gaging stations used in the analysis were the Branch River at Forestdale, Rhode Island (period of record 1957–1999) and the Nooseneck River at Nooseneck, Rhode Island (period of record 1964–1980). A regression equation was used to estimate unknown base-flow contributions from sand and gravel deposits at the two stations. The base-flow contributions from sand and gravel deposits and till deposits at the index stations were computed for June, July, August, and September within the periods of record, and divided by the area of each type of surficial deposit at each index station. These months were selected because they define a period when there is usually an increased demand for water and little to no precipitation. The base flows at the stream-gaging station Branch River at Forestdale, Rhode Island were lowest in August at the 75th, 50th, and 25th percentiles (29.67, 21.48, and 13.30 Mgal/d, respectively). The base flows at the stream-gaging station Nooseneck River at Nooseneck, Rhode Island were lowest in September at the 75th percentile (3.551 Mgal/d) and lowest in August at the 50th and 25th percentiles (2.554 and 1.811 Mgal/d).

The base flows per unit area for the index stations were multiplied by the areas of sand and gravel and till in the study-area subbasins to determine the amount of available water for each scenario. The water availability in the Pawtuxet River Basin at the 50th percentile ranged from 126.5 Mgal/d in August to 204.7 Mgal/d in June, and the total gross water availability for the 7-day, 10-year low-flow scenario at the 50th percentile ranged from 112.2 Mgal/d in August to 190.4 Mgal/d in June. The Scituate Reservoir safe yield was 83 Mgal/d in all scenarios. Water availability in the Quinebaug River Basin ranged from 13.94 Mgal/d in August to 30.53 Mgal/d in June at the 50th percentile. The total gross water availability for the 7-day, 10-year low-flow scenario at the 50th percentile ranged from 14.26 Mgal/d in August to 42.69 Mgal/d in June.

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 compared to water withdrawals in the basin and subbasins. The ratios of water withdrawn to water available were calculated for the 75th, 50th, and 25th percentiles for the subbasins; the closer the ratio is to 1, the closer the withdrawals are to the estimated water available, and the less net water is available. Withdrawals in July were higher than in the other summer months in both basins. In the Pawtuxet River Basin, the ratios were close to 1 in July for the estimated gross yield (from sand and gravel and from till and from the Scituate Reservoir safe yield), 7-day, 10-year low-flow scenario, and Aquatic Base Flow scenario at the 75th percentile and inAugust for all three scenarios atthe 50th and 25th percentiles. In the Quinebaug River Basin, the ratios were close to 1 in August for the estimated gross yield; 7-day, 10-year low-flow scenario; and Aquatic Base Flow scenario.

A long-term water budget was calculated for 1941 through 1999 to identify and assess the basin and subbasin inflow and outflows for the Pawtuxet and Quinebaug River Basins. The water withdrawals and return flows used in the budget were from 1995 through 1999. Inflow was assumed to be equal to outflow; total inflows and outflows were 574.9 Mgal/d in the Pawtuxet River Basin and 148.4 Mgal/d in the Quinebaug River Basin. Precipitation and return flow were 95 and 5 percent of the estimated inflows to the Pawtuxet River Basin, respectively. Precipitation was 100 percent of the estimated inflow to the Quinebaug River Basin; return flow was less than 1 percent of the inflow. Evapotranspiration, streamflow, and water withdrawals were 46, 41, and 13 percent, respectively, of the estimated outflows in the Pawtuxet River Basin. Evapotranspiration and streamflow were 49 and 51 percent, respectively, of the estimated outflows in the Quinebaug River Basin. Water withdrawals were less than 1 percent of outflows in the Quinebaug River Basin.

Contents

Abstract

Introduction

Purpose and Scope

Previous Investigations

Climatological Setting

The Pawtuxet River Basin

Land Use

Pawtuxet River Subbasins

Minor Civil Divisions

The Quinebaug River Basin

Estimated Water Use

New England Water-Use Data System

Public Water Supply and Interbasin Transfers

Domestic Water Use

Public-Supply Use in the Pawtuxet and Quinebaug River Basins

Self-Supply Use in the Pawtuxet and Quinebaug River Basins

Commercial and Industrial Water Use

Public-Supply Use in the Pawtuxet River Basin

Self-Supply Use in the Pawtuxet and Quinebaug River Basins

Agricultural Water Use

Return Flow and Interbasin Transfers

Site-Specific Return Flow in the Pawtuxet River Basin

Aggregate Return Flow in the Pawtuxet and Quinebaug River Basins

Interbasin Transfers in the Pawtuxet River Basin

Estimated Water Availability in the Summer

Pawtuxet River Basin

Quinebaug River Basin

Water Budget

Pawtuxet River Basin

Quinebaug River Basin

Summary

Acknowledgments

Selected References

Glossary

Figures

1. Map showing towns and climatological stations in the Pawtuxet River Basin, central Rhode Island, and Quinebaug River Basin, western Rhode Island

2–3. Diagrams showing:

2. The hydrologic cycle

3. The components of water use

4–10. Maps showing

4. Subbasins in the Pawtuxet and Quinebaug River Basins

5. Aquifers and selected production wells for the subbasins in the Pawtuxet and Quinebaug River Basins

6. The 8-, 10-, and 12-digit Watershed Boundary Dataset delineations for the Pawtuxet and Quinebaug River Basins

7. Scituate Reservoir Complex subbasin with selected partial-record stream-gaging stations and surficial deposits, Pawtuxet River Basin

8. Stream-gaging stations, Rhode Island Pollutant Discharge Elimination System sites, and wastewater-treatment plants associated with the Pawtuxet and Quinebaug River Basins

9. The Quinebaug River Basin in western Rhode Island, northeastern Connecticut, and south-central Massachusetts

10. Public water-supply districts associated with the Pawtuxet River Basin and in the northern Narragansett Bay area, Rhode Island

11–16. Diagrams showing:

11. Johnston Water District interconnections, purchases, distribution, exports, and estimated water uses in the Pawtuxet River Basin, 1995–99

12. Kent County Water Authority withdrawals, interconnections, purchases, distribution, exports, and estimated water uses, central Rhode Island, 1995–99

13. Providence Water Supply Board A, withdrawals, interconnections, distribution, and estimated water uses, central Rhode Island; and B, retail distribution, exports, and estimated water uses, 1995–99

14. Warwick Water Department interconnections, purchases, distribution, exports, and estimated water uses, central Rhode Island, 1995–99

15. Public-supply withdrawals and estimated exports from the Pawtuxet River Basin, 1995–99

16. Estimated public wastewater collection, discharge, and estimated exports from the Pawtuxet River Basin, 1995–99

17–18. Graphs showing:

17. Estimated water availability for June, July, August, and September from sand and gravel deposits for the subbasins in the Pawtuxet and Quinebaug River Basins for the A, 50th percentile; B, 50th percentile for the 7-day, 10-year low-flow scenario; and C, 50th percentile for the Aquatic Base Flow scenario

18. Estimated water availability for June, July, August, and September from till deposits for the subbasins in the Pawtuxet and Quinebaug River Basins for the A, 50th percentile; B, 50th percentile for the 7-day, 10-year low-flow scenario; and C, 50th percentile for the Aquatic Base Flow scenario

19. Maps showing the water withdrawal-to-availability ratios in A, June; B, July; C, August; and D, September for the subbasins in the Pawtuxet and Quinebaug River Basins at the 50th percentile for the 7-day, 10-year low-flow scenario

Tables

1. Summary of National Oceanic and Atmospheric Administration climatological stations and data pertinent to the Pawtuxet River Basin, central Rhode Island, and to the Quinebaug River Basin, western Rhode Island, 1995–99

2. Total town populations by subbasin for 1990, estimated populations for 1995–99, and estimated populations on public and self-supply and on public and self-disposal in the Pawtuxet and Quinebaug River Basins, 1995–992. Total town populations by subbasin for 1990, estimated populations for 1995–99, and estimated populations on public and self-supply and on public and self-disposal in the Pawtuxet and Quinebaug River Basins, 1995–99

3. Town land area and land-use area by category in the subbasins of the Pawtuxet and Quinebaug River Basins, 1995–99

4. Land-use area and percentage of land-use area by major public water-supply district for the subbasins in the Pawtuxet River Basin study area and areas outside of the Pawtuxet River Basin, 1995–99

5. Defined subbasins in the Pawtuxet and Quinebaug River Basin study areas compared to the 10-digit and 12-digit Natural Resources Conservation Service Watershed Boundary Dataset (2003)

6. Summary of total town land area, land area in the Pawtuxet and Quinebaug River Basins, total 1990 town populations and estimated 1995–99 populations, and land-use area by category in the Pawtuxet and Quinebaug River Basins

7. Withdrawals by major public water-supply districts in and outside the subbasins of the Pawtuxet River Basin, 1995–99

8. Minor public water suppliers by subbasin in the Pawtuxet and Quinebaug River Basins, 1995–99

9. Ground-water and surface-water withdrawals by town and subbasin in the Pawtuxet and Quinebaug River Basins, 1995–99

10. Average withdrawals and purchases for the Kent County Water Authority for June, July, August, and September, 1995–99

11. Withdrawals, discharges, retail sales, and wholesale purchases for the Providence Water Supply Board system in June, July, August, and September, 1995–99

12. Estimated water use by town and subbasin in the Pawtuxet and Quinebaug River Basins, 1995–99

13. Estimated consumptive water use by town and subbasin in the Pawtuxet and Quinebaug River Basins, 1995–99

14. Estimated water use for each 2-digit Standard Industrial Classification code by town in the Pawtuxet and Quinebaug River Basins, 1995–99

15. Estimated public- and self-disposed domestic, commercial, industrial, and metered return flow by subbasin in the Pawtuxet and Quinebaug River Basins, 1995–99

16. Return flows by subbasin for the Rhode Island Pollutant Discharge Elimination System sites in the Pawtuxet River Basin, 1995–99

17. Return flow from wastewater-treatment facilities within and outside of the Pawtuxet River Basin, 1995–99

18. Summary of estimated water withdrawals, imports, exports, use, consumptive use, and return flow in the Pawtuxet River Basin, 1995–99

19. Summary of estimated water withdrawals, imports, exports, use, consumptive use, and return flow in the Quinebaug River Basin, 1995–99

20. U.S. Geological Survey stream-gaging stations and minimum streamflows used in the analysis of water availability in the Pawtuxet and Quinebaug River Basins, 1995–99

21. Summer gross yields for the index stream-gaging stations used in the water-availability analysis in the Pawtuxet and Quinebaug River Basins

22. Estimated gross yields; gross yields minus the 7-day, 10-year low flow; and gross yields minus the Aquatic Base Flow per unit area for the two index stations used to determine water availability for June, July, August, and September in the Pawtuxet and Quinebaug River Basins

23. Estimated ground-water availability and total availability for June, July, August, and September in the Pawtuxet River Basin, 1995–99

24. Average water withdrawals for June, July, August, and September in the subbasins of the Pawtuxet River Basin, 1995–99

25. Summary of water withdrawal-to-availability ratios for June, July, August, and September in the Pawtuxet River Basin, 1995–99

26. Estimated gross yield; gross yield for the 7-day, 10-year low-flow scenario; and gross yield for the Aquatic Base Flow scenario for June, July, August, and September in the Quinebaug River Basin

27. Average water withdrawals for June, July, August, and September in the towns in the Quinebaug River Basin, 1995–99

28. Summary of water withdrawal-to-availability ratios for June, July, August, and September in the Quinebaug River Basin, 1995–99

29. Average water budget by subbasin for the Pawtuxet River Basin

30. Average water budget for the Quinebaug River Basin


Suggested Citation:

Wild, E.C., and Nimiroski, M.T., 2007, Estimated water use and availability in the Pawtuxet and Quinebaug River Basins, Rhode Island, 1995–99: U.S. Geological Survey Scientific Investigations Report 2006–5154, 68 p.


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