Specific Conductance Measurements in Central and Western 

New York Streams—A Retrospective Characterization

Ketchumville Branch of Nanticoke Creek, near Maine, N.Y.

Introduction

U.S. Geological Survey (USGS) Data Rescue Program 

funds were used to recover data from paper records for 

139 streamgages across central and western New York State; 

6,133 different streamflow measurement forms, collected 

between 1970–80, contained field water-quality measurements. 

The water-quality data were entered, reviewed, and uploaded 

into the USGS National Water Information System. In total, 

4,285 unique site visits were added to the database. The new 

values represent baseline water quality from which to measure 

change and will lead to a comparison of water-quality change 

over the last 40 years and into the future. Specific conductance 

was one of the measured properties and represents a simple way 

to determine if ambient inorganic water quality has been altered 

by anthropogenic (road salt runoff, wastewater discharges, or 

natural gas development) or natural sources.

The objective of this report is to describe ambient specific 

conductance characteristics of surface water across the central 

and western part of New York. This report presents median 

specific conductance of stream discharge for the period 1970–80 

and a description of the relation between specific conductance 

and concentrations of total dissolved solids (TDS) retrieved 

from the USGS National Water Information System (NWIS) 

database from 1955 to present. The data descriptions provide 

a baseline of surface-water specific conductance data that can 

used for comparison to current and future measurements in 

New York streams.

U.S. Department of the Interior

U.S. Geological Survey

Open-File Report 2012–1174 

September 2012
2

Synopsis of Regional Specific Conductance Data

Specific conductance, measured in microsiemens per 

centimeter (μS/cm) at 25 degrees Celsius (°C), hereafter 

referred to as specific conductance, is a standardized measure 

of the ability of water to conduct an electric current and 

is related to the amount of ions (atoms with negative and 

positive charges) in the water. A similar related measurement 

is the amount of TDS in water, measured in milligrams per 

liter (mg/L). While a specific conductance measurement 

can be made using a simple, hand-held meter and probe, the 

measurement of TDS requires a water sample be collected and 

sent to a laboratory where a specified volume of filtered water is 

evaporated, and the amount of solids left behind is then weighed 

and reported. In either case, these measurements determine the 

general inorganic (ionic) quality of the water.

The USGS in New York has collected surface-waterquality data since the 1950s; however, consistent and reliable 

water-quality information has only been retained in electronic 

databases since the late 1960s. In the 1970s, USGS hydrologists 

measured specific conductance as part of their visits to USGS 

streamgages across the United States. At the Ithaca office of the 

USGS New York Water Science Center, specific conductance 

data were collected at 119 streamgages between 1970 and 

1980 for most streamgages in central and western New York 

(fig. 1); the Troy office of the USGS New York Water Science 

Center provided data from an additional 20 streamgages 

from the Delaware River Basin in New York for this report. 

These data were not collected regularly at all streamgages for 

the entire 10-year period because measurement meters were 

usually shared within the office and were susceptible to extreme 

outdoor temperature and battery failure. Furthermore, the 

results from these data were never transferred from the field 

notes to an electronic database system until recently through the 

USGS Data Rescue Program (Wippich, 2012). This program 

seeks to identify and preserve science data and information at 

Lake Ontario

Lake Erie

NEW YORK

PENNSYLVANIA

NEW YORK

NEW JERSEY

SUSQUEHANNA

RIVER BASIN

HUDSON

RIVER BASIN

DELAWARE RIVER BASIN

OSWEGO

RIVER

BASIN

GENESEE

RIVER

BASIN

BLACK

RIVER BASIN

ST. LAWRENCE RIVER BASIN

 LAKE

ONTARIO

EAST

LAKE ONTARIO CENTRAL

LAKE ONTARIO WEST

LAKE

ERIE

BASIN

ALLEGENY

RIVER BASIN

Syracuse

Rochester

Buffalo

Binghamton

CANADA

80° 79° 78° 77° 76° 75° 74°

44°

43°

42°

41°

EXPLANATION

Streamstats watershed boundary

State boundary

County boundary

City

River basin boundary

Monitoring site - Susquehanna River Basin Commission

Monitoring site - U.S. Geological Survey

Specific Conductance Monitoring Site

0 25 50 MILES

0 25 50 KILOMETERS

ST. LAWRENCE RIVER BASIN

Base from U.S. Geological Survey,

digital data, 1983, 1:100,000

Universal Transverse Mercator projection,

Zone 18, NAD 83

Figure 1. Locations of the watersheds of seven major river basins in New York where specific conductance measurements were 

collected between 1970–80 and where current (2012) near-real-time specific conductance streamgages are in operation in New York. 

Major river basins are outlined and named, while smaller watersheds are variously colored.
3

risk of loss due to obsolescence of media or formats, or from 

their storage environment, or both. The goal of this program 

is to make the unique USGS information accessible and 

available to the broadest possible audience and allow for new 

data interpretations that were never intended by the original 

collector. Since the 1980s, all water-quality data collected by 

the USGS have been entered directly into the NWIS database.

This report presents results of specific conductance data 

collected during water years1 1970 through 1980 at streamgages 

in central and western New York. Specific conductance 

data from NWIS were also used to verify the quality of data 

collected in the 1970s and to determine the relation between 

specific conductance and concentrations of total dissolved 

solids in New York streams when data for both properties were 

collected concurrently.

Specific Conductance Data by Streamgage

Stream discharge measurement field sheets for central and 

western New York beginning in the 1970 water year are stored 

in the files of the Ithaca office of the USGS New York Water 

Science Center. Field sheets were retrieved and the pertinent 

data transferred for water years 1970 through 1980 to electronic 

spreadsheets for inclusion into the NWIS database. Specific 

conductance data for a total of 139 watersheds (fig. 1) were 

retrieved and entered into the NWIS system (U.S. Geological 

Survey, undated). The data were analyzed to determine the 

range of specific conductance, data variability, and possible 

temporal trends over the period of record for each streamgage.

1

Water year—The water year begins in October of the previous calendar 

year through September of the year of record, for example, water year 1970 is 

October 1, 1969, through September 30, 1970.

At all streamgages, annual variability in specific 

conductance was noted to usually fall within one order of 

magnitude of the median specific conductance for each 

streamgage. This range in values could be attributed to either 

change in the volume of stream flow and (or) seasonal effects, 

such as dissolved road salt runoff entering the stream. In 

this study, the median value of specific conductance at each 

streamgage for the period of record (1970–80) was used as a 

means to compare specific conductance between streamgages in 

central and western New York.

NWIS Data by Major River Basin

In New York, data for more than 12,000 individual surfacewater and groundwater sites are stored in the New York portion 

of the NWIS database; the surface-water records go back to 

the early 1950s. Data for all streamgages in New York State 

were initially queried, and streamgages in the lower Hudson 

River Basin and on Long Island were eliminated due to the 

possible influence of tidal sea water on specific conductance. 

Approximately 44,000 individual data points representing 

1,858 streamgages were then queried to select a representative 

specific conductance value for each streamgage within 10 New 

York river basins (Allegheny, Black, Delaware, Genesee, upper 

Hudson, Lake Erie (direct drainage), Lake Ontario (direct 

drainage), Oswego, St. Lawrence, and Susquehanna Rivers 

Basins; fig. 2). The number of streamgages selected for each 

drainage basin varied from as few as 71 in the Lake Erie directdrainage basin to 488 streamgages in the upper Hudson River 

basin. The resulting box and whisker plots (fig. 2) show the 

range of values by basin as well as the median value; the basin 

median values were used as a means to verify the median values 

of the streamgage data within each basin for the 1970s.

Allegheny

 River

 Basin Black

River

Basin

Delaware

 River

 Basin Genesee

 River

 Basin

Upper Hudson

 River Basin

Lake Erie

 Basin

Lake Ontario

 Basin

 Oswego

 River 

 Basin

St. Lawrence

 River Basin

Susquehanna

 River 

 Basin

100

101

102

103

104

105

Specific conductance,

in microsiemens per centimeter at 25 degrees Celcius

EXPLANATION

 (76) Number of streamgages

Individual observations 

above 90th percentile

90th percentile

25th percentile

50th percentile (median)

75th percentile

10th percentile

1,123 

Individual observations 

below 10th percentile

Number of samples

1.677

(264)

1,281

(74)

2,869

(321)

3,240

(108)

1,365

(71)

17,233

(488)

3,206

(115)

11,690

(265)

1.116

(76)

423

(76)

Figure 2. Box plots of specific conductance data at 1,858 streamgages within 10 major river basins in New York, showing numbers 

of streamgages for each basin, median values (red dots), first and third quartile ranges (brackets), and outliers (black dots). The 

Long Island and Hudson River Basins were not included in the study because of possible influence of tidal sea water on specific 

conductance. 
4

As a result of this assessment 

(fig. 2), it was determined that the 

median specific conductance for 

265 streamgages within the Delaware 

River Basin had the lowest (27 μS/cm) 

median specific conductance value of the 

entire study area; specific conductance 

in this study area ranged between 17 

and 424 μS/cm. The greatest median 

specific conductance values were at 

the Lake Onatrio direct drainage basin 

(698 μS/cm with 108 streamgages) and 

the Oswego River Basin (680 μS/cm 

with 321 streamgages) with a range from 

about 30 to more than 22,000 μS/cm. 

Some of the largest specific conductance 

values occurred in basins associated 

with either streamflow within an oil or 

gas development area in the Allegheny 

River Basin or from natural brine 

springs and a former industrial brineprocessing facility in the Onondaga 

Creek watershed (Oswego River 

Basin). Additionally, large specific 

conductance values were associated with 

anthropogenic sources, such as road salt 

runoff or wastewater treatment discharge 

from larger urban areas, such as Buffalo, 

Rochester, and Syracuse, in upstate 

New York.

The intent of compiling the NWIS data was to verify 

the quality of the specific conductance data collected for 

1970 through 1980. While specific conductance data are 

easily collected today using a temperature-compensated 

meter, the 1970s method was more involved and prone to 

measurement error as the water sample was small, placed in a 

small measuring cup for analysis, and the result needed to be 

manually compensated using a field thermometer to the 25°C 

standard. Comparing the median values for each station to those 

of the major river basin data from the NWIS database indicates 

that the two sets of data are comparable.

Comparison of Specific Conductance to Total Dissolved Solids

Concentration of TDS can be used as a surrogate 

constituent for specific conductance, and at times these terms 

have, incorrectly, been used interchangeably. Hem (1985) 

indicated that, for natural waters across the United States, TDS 

can range between 0.55 and 0.75 percent of the value of specific 

conductance. Analysis of 1,858 paired specific conductance 

and TDS data records for New York from the NWIS database 

indicated that the ratio of TDS to specific conductance across 

New York was about 0.63—that is, a specific conductance 

measurement multipled by 0.63 should yield an equivalent 

TDS value. While the scatter of data points (fig. 3) is greater 

at the lower conductance range (less than 1,000 μS/cm), the 

ratio of 0.63 provides a good estimate of the concentration 

of TDS-derived specific conductance measurements at 

New York streamgages (fig. 3, regression equation and 

coefficient of determination (percent variability of TDS to 

specific conductance)).

Retrospective Characterization

The characterization of specific conductance data of 

samples from streams in central and western New York 

collected between 1970 and 1980 provides a baseline from 

which to assess future changes in stream-water quality due to 

anthropogenic sources (road salt runoff, wastewater discharges, 

or natural gas development). The variation in specific 

conductance across watersheds in central and western New York 

is affected by any combination of land use, geology (different 

types of bedrock produce different water quality), inflows from 

population centers [nonpoint sources of specific conductance 

and point sources, such as wastewater-treatment plants or 

industrial discharges], and dilution of base flow by stormwater 

runoff. Using the median specific conductance value takes 

into account these varying factors and best represents specific 

conductance at each streamgage and the watershed upstream 

from the streamgage, as shown in figure 4 for the period 

of record.

One aspect to be taken into account in determining any 

change in median specific conductance between the 1970s and 

the present (2012) is the increased use of halite (road salt) used 

for winter-time road deicing. The use of road salt for deicing 

began in the 1950s, increased nationally through the 1970s 

and 1980s, and continues into the present, in varying amounts, 

depending on winter weather conditions (fig. 5). Road salt usage 

in New York has likely followed the national trend. Currently 

(2012), New York uses about one million short tons of halite 

each year for deicing purposes (Linberg and others, 2009); this 

is likely the major source of change in specific conductance as 

measured in New York streams during and after the 1970s.

Y = 0.6257X + 0.9568

R2 = 0.9882

N = 1,858 PAIRED

OBSERVATIONS

1

10

100

1,000

10,000

100,000

1 10 100 1,000 10,000 100,000

Total dissolved solids, in milligrams per liter

Specific conductance,

microsiemens per centimeter at 25 degrees Celsius

Figure 3. Comparison of specific conductance and total dissolved solids 

measurements for 1,858 samples where both parameters were collected in surface 

waters of New York. The linear regression relation (represented by the black 

line) and coefficient of determination (R2

) value for those paired data points (blue 

diamonds) are also shown. Data do not include samples from the lower Hudson 

River and streams on Long Island. 
5

Lake Ontario

Lake Erie

NEW YORK

PENNSYLVANIA

NEW YORK

NEW JERSEY

SUSQUEHANNA

RIVER

BASIN

HUDSON

RIVER

BASIN

DELAWARE RIVER BASIN

OSWEGO

RIVER

BASIN

GENESEE

RIVER

BASIN

BLACK

RIVER

BASIN

LAKE

ONTARIO

EAST

LAKE ONTARIO CENTRAL

LAKE ONTARIO WEST

LAKE

ERIE

BASIN

ALLEGENY

RIVER

BASIN

ST. LAWRENCE RIVER BASIN

Syracuse

Rochester

Buffalo

Binghamton

80° 79° 78° 77° 76° 75° 74°

44°

43°

42°

41°

EXPLANATION

101–300 

301–500

501–700

0–100

>900

701–900

No data

StreamStats watershed boundary

State boundary

County boundary

City

Major basin boundary

Median specific conductance, 

in microseimens per centimeter

at 25 degrees Celsius

0 25 50 MILES

0 25 50 KILOMETERS

Base from U.S. Geological Survey,

digital data, 1983, 1:100,000

Universal Transverse Mercator projection,

Zone 18, NAD 83

Figure 4. Ranges of median specific conductance values for 139 watersheds in central and western New York based on specific 

conductance data collected by the U.S. Geological Survey between 1970 and 1980. StreamStats watershed boundaries are from U.S. 

Geological Survey (2011).

Current Specific Conductance Monitoring

Currently (2012), several agencies, including the 

Susquehanna River Basin Commission (SRBC; undated), 

monitor and report specific conductance data in conjunction 

with natural gas development activities. The SRBC has about 

30 water-quality sites in Pennsylvania and 10 in New York, 

which monitor specific conductance and several other waterquality properties (fig. 1). These data are then made available on 

the Internet. The USGS Water Science Center in Pennsylvania 

has also implemented similar specific conductance monitoring 

at 10 streamgages in northern and western Pennsylvania to 

address potentrial changes in stream water quality due to natural 

gas development activities. The USGS Water Science Center in 

New York, in cooperation with the New York State Department 

of Environmental Conservation (NYSDEC), has installed 

similar real-time specific conductance monitoring equipment at 

two steamgages on the Susquehanna River and one streamgage 

on the Delaware River (fig. 1) in areas where natural gas 

development could occur in the near future.

Summary

U.S. Geological Survey (USGS) Data Rescue Program 

funds were used to recover data from paper records for 

139 streamgages across central and western New York State; 

6,133 different streamflow measurement forms, collected 

between 1970–80, contained field water-quality measurements. 

The water-quality data were entered, reviewed, and uploaded 

into the USGS National Water Information System (NWIS). 

In total, 4,285 unique site visits were added to the database. 

The new values represent baseline water quality from which 

to measure change and will lead to a comparison of waterquality change over the last 40 years and into the future. 
6

Specific conductance was one of the measured properties and 

represents a simple way to determine if ambient inorganic 

water quality has been altered by anthropogenic (road salt 

runoff, wastewater discharges, or natural gas development) or 

natural sources.

This report describes ambient specific conductance 

characteristics of surface water across the central and western 

part of New York. This report presents median specific 

conductance of stream discharge for the period 1970–80 and 

a description of the relation between specific conductance 

and concentrations of total dissolved solids (TDS) retrieved 

from the USGS NWIS database from 1955 to present. The 

data descriptions provide a baseline of surface-water specific 

conductance data that can be used for comparison to current 

and future measurements in central and western New York 

streams.

The potential for further change in stream specific 

conductance may be anticipated due to changes in various 

anthropogenic sources, including the ongoing use of road salt 

for deicing and potential natural gas development. Through 

continued monitoring and characterization of water quality, 

including specific conductance monitoring, the effects of 

anthropogenic influences on streams and rivers in New York can 

be documented. Specific conductance will be one of the simpler 

methods that can be used to determine if these anthropogenic 

influences have any additional effect on the water resources of 

New York.

Road salt, in millions of short tons

0

2

4

6

8

10

12

Year

14

16

18

20

22

1950 1954 19861982197819741970196619621958 1990 1994 200620021998

Figure 5. Trend in road salt use in the United States from 1950 

through 2004. Adapted from Transportation Research Board (1991; data 

for 1950–1988) and Mullaney and others (2009; data for 1990–2004).

By William M. Kappel, Gaylen J. Sinclair, James E. Reddy, David A. Eckhardt, M. Peter deVries, and Margaret E. Phillips

References Cited

Hem, J.D., 1985, Study and interpretation of the chemical 

characteristics of natural water: U.S. Geological Survey 

Water-Supply Paper 2254, 263 p.

Linberg, Tim, Lorey, Scott, and Houseal, Brian, 2009, 

Low sodium diet—Curbing New York’s appetite for 

damaging road salt: Elizabethtown, New York, Adirondack 

Council, 40 p., accessed June 19, 2012, at http://www.

adirondackcouncil.org/Road%20Salt%20Report209.pdf.

Mullaney, J.R., Lorenz, D.L., and Arntson, A.D., 

2009, Chloride in groundwater and surface water 

in areas underlain by the glacial aquifer system, 

northern United States: U.S. Geological Survey 

Scientific Investigations Report 2009–5086, 41 p., 

at http://pubs.usgs.gov/sir/2009/5086/pdf/sir2009-5086.pdf.

Susquehanna River Basin Commission, [not dated], Overview: 

Susquehanna River Basin Commission, accessed June 19, 

2012, at http://mdw.srbc.net/remotewaterquality/.

Transportation Research Board, 1991, Highway deicing—

Comparing salt and calcium magnesium acetate: Washington, 

D.C., Transportation Research Board National Research 

Council Special Report 235, 168 p., accessed January 

19, 2012, at http://onlinepubs.trb.org/onlinepubs/sr/

sr235/017–030.pdf.

U.S. Geological Survey, 2011, Welcome to StreamStats: 

U.S. Geological Survey, accessed June 20, 2012, 

at http://water.usgs.gov/osw/streamstats/.

U.S. Geological Survey, [not dated], USGS data for New 

York: U.S. Geological Survey, accessed June 19, 2012, 

at http://waterdata.usgs.gov/ny/nwis/nwis.

Wippich, Carol, 2012, Preserving science for the ages—USGS 

data rescue: U.S. Geological Survey Fact Sheet 2012–3078, 

4 p., at http://pubs.usgs.gov/fs/2012/3078/.

For more information, please contact:

New York Water Science Center

U.S. Geological Survey

30 Brown Road 

Ithaca, New York 14850

Information request:

(518) 285-5602

or visit our Web site at:

http://ny.water.usgs.gov

For more information on the USGS—the Federal source for science 

about the Earth, its natural and living resources, natural hazards, and the 

environment, visit http://www.usgs.gov or call 1–888–ASK–USGS.

For an overview of USGS information products, including maps, imagery, 

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