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Sources of Sodium and Chloride in the Scituate Reservoir Drainage Basin, Rhode Island

Water-Resources Investigations Report 02-4149

By Mark T. Nimiroski and Marcus C. Waldron

The Scituate Reservoir system is the principal drinking-water supply for more than 60 percent of the population of Rhode Island. Sodium concentrations in the reservoir have been increasing slowly in recent years despite the long-term (12 years) use of a reduced-sodium deicing agent on State-maintained highways in the reservoir drainage basin. This report identifies the major sources of sodium and chloride in the drainage basin, and assesses the relative contribution of each source to the total amounts of these constituents that entered the basin from October 1999 through September 2000 (Water Year 2000).

Findings

CONTENTS

Introduction
Description of the Scituate Reservoir Drainage Basin 
Sodium and Chloride Enter the Scituate Reservoir Drainage Basin from Multiple Sources
Deicing Activities Contributed More Sodium and Chloride to the Drainage Basin During Water Year 2000 Than Any Other Source 
Tributary-Stream Concentrations of Sodium and Chloride Are Directly Related to the Densities of State-Maintained Roads in the Stream Drainage Areas
Sodium Concentrations in Tributary Streams Did Not Decrease Following a State-Mandated Reduction in the Rate of Sodium Applied to State-Maintained Roads in the Drainage Basins
Summary and Conclusions
References Cited

MORE INFORMATION BOXES

Quantifying Sources of Sodium and Chloride 
Precipitation
Road-Salt Applications
Other Deicing Activities
Septic-System Leachate
Geologic Weathering

FIGURES

  1. Location and hydrography of the Scituate Reservoir drainage basin, Rhode Island.

  2. Potential sources and transport pathways of sodium and chloride in the Scituate Reservoir drainage basin, Rhode Island.

  3. Locations of Providence Water Supply Board water-quality-monitoring stations sampled from 1983 to 2000 in relation to (A) State and local roads, and (B) subbasin boundaries in the Scituate Reservoir drainage basin, Rhode Island.

  4. Relations between median stream-sodium concentrations during 19832000, and the density of State-maintained and locally maintained roads in 31 subbasins of the Scituate Reservoir drainage basin, Rhode Island

  5. Relations between median stream-chloride concentrations during 19832000, and the density of State-maintained and locally maintained roads in 31 subbasins of the Scituate Reservoir drainage basin, Rhode Island.

  6. Relations between median stream-sodium concentrations and the density of State-maintained roads in 3 subbasins of the Scituate Reservoir drainage basin, Rhode Island, during the periods 198389 and 19902000.

TABLE

  1. Major sources of sodium and chloride in the Scituate Reservoir drainage basin, Rhode Island, October 1999 through September 2000

AVAILABILITY

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PDF version of report  2,7MB

The citation for this report, in USGS format, is as follows:

Nimiroski, M.T. and Waldron, M.C., Sources of Sodium and Chloride in the Scituate Reservoir Drainage Basin, Rhode Island: U.S. Geological Survey Water-Resources Investigations Report 02-4149, 16 p.

For more information about USGS activities in Massachusetts-Rhode Island District, visit the USGS Massachusetts-Rhode Island Home Page.



U.S. Department of the Interior, U.S. Geological Survey
Persistent URL: http://pubs.water.usgs.gov/wri024149
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Last modified: Friday, September 16 2005, 04:22:46 PM
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