U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2012–5144

Prepared in cooperation with the 

New York City Department of Environmental Protection

Preliminary Assessment of Water Chemistry

Related to Groundwater Flooding in 

Wawarsing, New York, 2009–11
Cover. A, U.S. Geological Survey scientist sampling a domestic well in Wawarsing, New York. B, Basement flooding in Wawarsing, New York. 

C, U.S. Geological Survey scientists logging a domestic well in Wawarsing, New York. D, Basement pumpage discharging to a flooded street in 

Wawarsing, New York.

A

C

B

D
Preliminary Assessment of Water 

Chemistry Related to Groundwater Flooding 

in Wawarsing, New York, 2009–11

By Craig J. Brown, David A. Eckhardt, Frederick Stumm, and Anthony Chu

Prepared in cooperation with the 

New York City Department of Environmental Protection

Scientific Investigations Report 2012–5144

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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Suggested citation:

Brown, C.J., Eckhardt, D.A., Stumm, Frederick, and Chu, Anthony, 2012, Preliminary assessment of water chemistry 

related to groundwater flooding in Wawarsing, New York, 2009–11: U.S. Geological Survey Scientific Investigations 

Report 2012–5144, 36 p. (Also available at http://pubs.usgs.gov/sir/2012/5144/.)
iii

Acknowledgments

The authors would like to thank Ira Stern and William Richardson of the New York City 

Department of Environmental Protection, Bureau of the Grahamsville Region, Western 

Operations Division, for providing data and information and for granting access to the Rondout 

mixing chamber. In addition, the authors would like to thank the residents of the town of 

Wawarsing, New York, for allowing access to collect samples from wells and springs on their 

properties and for providing information related to flooding. Thanks are extended to the town of 

Wawarsing for granting access to monitoring sites at Lippman Park and to James Rodden, Jr., 

of the Ulster County Health Department, who provided water-quality data on homeowner wells. 

Special thanks are extended to Paul Heisig, U.S. Geological Survey New York Water Science 

Center, for providing technical support and establishing part of the groundwater network.
THIS PAGE INTENTIONALLY LEFT BLANK
v

Contents

Acknowledgments........................................................................................................................................iii

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

Introduction.....................................................................................................................................................1

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

Description of Study Area ...................................................................................................................2

Previous Investigations........................................................................................................................3

Methods of Data Collection and Analysis .................................................................................................3

Design of Monitoring Network ...........................................................................................................3

Collection and Analysis of Water Samples ......................................................................................3

Quality Assurance...............................................................................................................................10

Hydrogeologic Setting.................................................................................................................................10

Geology.................................................................................................................................................10

Bedrock .......................................................................................................................................10

Unconsolidated Deposits .........................................................................................................11

Hydrology .............................................................................................................................................11

Water-Quality Monitoring Sites...............................................................................................11

Rondout Reservoir and the Rondout–West Branch Water Tunnel....................................11

Hydrologic Effects of Temporary Rondout–West Branch Water Tunnel Shutdowns.....16

Water Sources and Chemistry...................................................................................................................16

Sources of Water................................................................................................................................17

Major Constituents and Nutrients....................................................................................................17

Redox Conditions ................................................................................................................................17

Trace Constituents..............................................................................................................................20

Stable Isotopes....................................................................................................................................20

Groundwater Age................................................................................................................................21

Summary and Conclusions.........................................................................................................................22

References Cited..........................................................................................................................................23
vi

Figures

1. Map showing Wawarsing study area, including Port Jervis Trough (Kingston to 

Port Jervis), four reservoirs (Cannonsville, Pepacton, Neversink, and Rondout), 

Delaware Aqueduct, Roundout Reservoir sampling site 01366400 at the influent to 

Rondout–West Branch Tunnel, and Kensico Reservoir, in Westchester County, 

New York ........................................................................................................................................4

2. Map showing monitoring sites at a lake (Lippman Lake), springs, unconsolidated 

monitoring and supply wells, and bedrock supply wells in Wawarsing, Ulster County, 

New York ........................................................................................................................................6

3. A. Map showing locations of wells and surface-water sites; Rondout–West Branch 

Tunnel geology; and water-inflow rates documented during tunnel construction in 

the Wawarsing study area, Ulster County, New York. B. Cross section of geology 

observed during New York City Board of Water Supply test borings and Rondout–

West Branch Tunnel construction from A to A’ within the study area, Town of 

Wawarsing, Ulster County, New York .....................................................................................14

4. Piper diagram showing the percentage of total equivalents of major cations and 

anions in surface-water and groundwater samples collected from a lake, springs, 

and wells in Wawarsing and for the Rondout Reservoir at the influent to the Rondout–

West Branch Tunnel in Lackawack, Ulster County, New York, 2009–11............................18

5. Diagram showing saturation indexes for calcite and gypsum in surface-water and 

groundwater samples collected from a lake, springs, and wells in the study area, 

Wawarsing, New York, and for the Rondout Reservoir at the influent to the Rondout–

West Branch (RWB) Tunnel in Lackawack, Ulster County, New York, 2009–11...............19

Tables

1. Data on the sampling-site locations and construction of wells in the Wawarsing 

study area, and for the Rondout Reservoir at the influent to the Rondout–West 

Branch Tunnel in Lackawack, Ulster County, New York, 2009–11........................................8

2. Classes of water-quality chemical characteristics and constituents measured in 

water samples from a lake, springs, and wells in the Wawarsing study area, and for 

the Rondout Reservoir at the influent to the Rondout–West Branch Tunnel in 

Lackawack, Ulster County, New York, 2009–11 .......................................................................9

3. General chemical characteristics, concentrations of major elements and nutrients, 

saturation indexes, and percent charge balance error in surface-water and 

groundwater samples from a lake, springs, and wells in the Wawarsing study area, 

and for the Rondout Reservoir at the influent to the Rondout–West Branch Tunnel in 

Lackawack, Ulster County, New York, 2009–11 .....................................................................28

4. Concentrations of dissolved gases and age tracers, redox properties, and apparent 

age of surface-water and groundwater samples from a lake, springs, and wells in 

the Wawarsing study area, and for the Rondout Reservoir at the influent to the 

Rondout–West Branch Tunnel in Lackawack, Ulster County, New York, 2009–11 ..........30

5. Dissolved concentrations of trace elements and stable-isotope ratios in surfacewater and groundwater samples from a lake, springs, and wells in the Wawarsing 

study area, and for the Rondout Reservoir at the influent to the Rondout–West 

Branch Tunnel in Lackawack, Ulster County, New York, 2009–11......................................34
vii

Conversion Factors, Datum, and Abbreviations

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2

) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

gallon (gal) 0.003785 cubic meter (m3

)

Flow rate

gallon per minute (gal/min) 0.06309 liter per second (L/s)

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

/d)

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

/s)

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

Inch/Pound to SI

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

 °F=(1.8×°C)+32

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

(NAVD 88) or the National Geodetic Vertical Datum of 1929 (NGVD 29).

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

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

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25°C).

Concentrations of chemical constituents in water are given either in parts per trillion by volume 

(pptv), milligrams per liter (mg/L), picograms per liter (pg/L), molarity, or moles per liter (mol/L),

milligrams per kilogram (mg/kg), picomoles per kilogram (pmol/kg), or femtomoles per kilogram 

(femtomol/kg), cubic centimeters per liter at standard temperature and pressure (cm3

STP/L), or 

picoCuries per liter (pCi/L).
viii

> greater than

< less than

Abbreviations

δ delta

E estimated concentration

IAP/Ksp ratio of ion activity product to solubility product coefficient

MCL maximum contaminant levels

MRL minimum reporting level

MVT Mississippi Valley Type

MWL meteoric water line

NAWQA National Water Quality Assessment Program

NOAA National Oceanic and Atmospheric Administration

NWQL National Water Quality Laboratory

NWS National Weather Service

NYC New York City

NYCDEP New York City Department of Environmental Protection

RWB Rondout–West Branch

TEAP terminal electron-accepting processes

USGS U.S. Geological Survey

VCDT Vienna Canyon Diablo Troilite

VOC volatile organic compound

VPDB Vienna Pee Dee Belemnite

VSMOW Vienna Standard Mean Ocean Water

Ag silver

Ar argon

As arsenic

B boron

Ba barium

Be beryllium

Br- bromide

Ca calcium

Cd cadmium

CH4 methane

CFCs chlorofluorocarbons

Co cobalt

CO2 carbon dioxide

Cr chromium

Cu copper

DIC dissolved inorganic carbon
ix

DO dissolved oxygen

E. coli Escherichia coli F- fluoride

Fe iron H hydrogen 2H deuterium 3H tritium H2

S, HS

- hydrogen sulfide species

He helium

HNO

3 nitric acid

K potassium

Li lithium

Mb molybdenum

Mg magnesium

Mn manganese

N, N

2 nitrogen

Na sodium

NH

4

+ ammonium

Ni nickel

NO

2

- nitrite

NO

3

- nitrate

O

2 oxygen

P phosphorus

Pb lead

PO

4

2- phosphate

S sulfur

Se selenium

SF

6 sulfur hexafluoride

SO

4

2

- sulfate

SiO

2 silica

Sr strontium

Tl thallium U uranium V vanadium

Zn zinc
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Preliminary Assessment of Water Chemistry Related to 

Groundwater Flooding in Wawarsing, New York, 2009–11

By Craig J. Brown, David A. Eckhardt, Frederick Stumm, and Anthony Chu

Abstract

Water-quality samples collected in an area prone to 

groundwater flooding in Wawarsing, New York, were analyzed 

and assessed to better understand the hydrologic system and 

to aid in the assessment of contributing water sources. Above 

average rainfall over the past decade, and the presence of a 

pressurized water tunnel that passes about 700 feet beneath 

Wawarsing, could both contribute to groundwater flooding. 

Water samples were collected from surface-water bodies, 

springs, and wells and analyzed for major and trace inorganic 

constituents, dissolved gases, age tracers, and stable isotopes. 

Distinct differences in chemistry exist between tunnel water 

and groundwater in unconsolidated deposits and in bedrock, 

and among groundwater samples collected from some bedrock 

wells during high head pressure and low head pressure of the 

Rondout–West Branch Tunnel. Samples from bedrock wells 

generally had relatively higher concentrations of sulfate 

(SO4

2-), strontium (Sr), barium (Ba), and lower concentrations of calcium (Ca) and bicarbonate (HCO3

-

), as compared 

to unconsolidated wells. Differences in stable-isotope ratios 

among oxygen-18 to oxygen-16 (δ18O), hydrogen-2 to 

hydrogen-1 (δ2

H), sulfur-34 to sulfur-32 (δ34S) of SO4

2-, Sr-87 

to Sr-86 (87Sr/86Sr), and C-13 to C-12 (δ13C) of dissolved 

inorganic carbon (DIC) indicate a potential for distinguishing water in the Delaware–West Branch Tunnel from native 

groundwater. For example, 87Sr/86Sr ratios were more depleted 

in groundwater samples from most bedrock wells, as compared to samples from surface-water sources, springs, and 

wells screened in unconsolidated deposits in the study area.

Age-tracer data provided useful information on pathways 

of the groundwater-flow system, but were limited by inherent 

problems with dissolved gases in bedrock wells. The sulfur 

hexafluoride (SF6

) and (or) chlorofluorocarbons (CFCs) 

apparent recharge years of most water samples from wells 

screened in unconsolidated deposits and springs ranged 

from 2003 to 2010 (current) and indicate short flow paths 

from the point of groundwater recharge. All but three of the 

samples from bedrock wells had interference problems with 

dissolved gases, mainly caused by excess air from degassing 

of hydrogen sulfide and methane. The SF6

 and (or) CFC 

apparent recharge years of samples from three of the bedrock 

wells ranged from the 1940s to the early 2000s; the sample 

with the early 2000s recharge year was from a flowing artesian 

well that was chemically similar to water samples collected at 

the influent to the tunnel at Rondout Reservoir and the most 

hydraulically responsive to water tunnel pressure compared to 

other bedrock wells. 

Data described in this report can be used, together with 

hydrogeologic data, to improve the understanding of source 

waters and groundwater-flow patterns and pathways, and to 

help assess the mixing of different source waters in water 

samples. Differences in stable isotope ratios, major and trace 

constituent concentrations, saturation indexes, tritium concentrations, and apparent groundwater ages will be used to 

estimate the proportion of water that originates from Rondout–

West Branch Tunnel leakage.

Introduction

Groundwater flooding of streets and residential basements during fall 2008 in the Rondout Valley near the town of 

Wawarsing, Ulster County, New York, prompted the New York 

City Department of Environmental Protection (NYCDEP) to 

ask the U.S. Geological Survey (USGS) to characterize the 

groundwater-flow system of the area. Precipitation records 

indicate that above average rainfall over much of the past two 

decades, particularly over the past decade, has aggravated 

flooding problems (Stumm and others, 2012). Additionally, a 

segment of the Rondout–West Branch (RWB) Tunnel, which 

is an underground concrete-lined structure that passes about 

700 feet (ft) beneath Wawarsing and carries pressurized 

water through from the Catskill Mountains to New York City 

(NYC), is leaking and also could be contributing to groundwater flooding (Stumm and others, 2012). This 44-mile (mi) long, 

13.5-ft diameter water tunnel between the Rondout Reservoir 

and the Catskill Aqueduct carries about one-half of the NYC 

water supply and has a capacity of about 1.03 billion gallons 

per day (gal/d) (New York City Department of Environmental 

Protection, 2010). One of the two primary areas of leakage 

along the RWB Tunnel is beneath Wawarsing; during construction of the RWB Tunnel, this section of bedrock beneath 

the Rondout Valley was observed to be highly faulted and 
2 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

weathered, had over 9,000 gallons per minute (gal/min) of 

inflow, and required over 20,000 bags of concrete and steel 

reinforcements to stabilize the bedrock. The total estimated 

leakage out of the RWB Tunnel is 15 to 35 million gallons per 

day (Mgal/d) (James Canale, New York City Department of 

Environmental Protection, written commun., 2011; DiNapoli, 

2007). In 2003 and 2009, an autonomous underwater vehicle 

was used to inspect the interior of the RWB Tunnel and 

recorded 8,200 linear feet of cracking throughout the tunnel 

(James Canale, New York City Department of Environmental 

Protection, written commun., 2011). Most of the cracking was 

observed in the sections of the tunnel that are within the limestone units underlying Roseton and Wawarsing, N.Y.

Water-chemistry data were interpreted with hydrogeologic data, which are detailed in a companion report (Stumm 

and others, 2012), to help identify and distinguish between 

water sources that may contribute to the groundwater flooding observed in Wawarsing. Inorganic constituents, stable 

isotopes, and age tracers in groundwater and springs are 

useful indicators of different sources of water, including 

surface water or anthropogenic sources, as well as geochemical processes in different parts of the aquifer system. Waterchemistry data were interpreted with hydrogeologic data, 

which are detailed in a companion report (Stumm and others, 

2012), to help identify and distinguish between water sources 

that may contribute to the groundwater flooding observed 

in Wawarsing.

In 2008, the USGS was tasked by the NYCDEP to 

characterize the hydrogeologic conditions in the Wawarsing 

area and investigate the possible relation between groundwater flooding and leakage from the adjacent RWB Tunnel. 

A companion report (Stumm and others, 2012) describes the 

hydrology of the Wawarsing study area. Together, the reports 

serve as a foundation for understanding the hydrologic system 

and how it is affected by precipitation and pressurized water 

leaking from the RWB Tunnel.

Purpose and Scope

The purposes of this report are to describe the 

collection and analysis of water samples and to present some 

general interpretation of water-chemistry data in order to 

better understand the hydrologic system and to aid in the 

assessment of sources of groundwater flooding in the town 

of Wawarsing, N.Y. The report presents information on the 

hydrogeologic setting, the occurrence and distribution of 

chemical constituents and characteristics, and groundwaterage estimates for groundwater samples in the study area. 

Hydrogeologic data from a companion report (Stumm and 

others, 2012) are used in this analysis. The report presented 

herein describes general water-chemistry characteristics, such 

as oxidation-reduction (redox) conditions, pH, and water types 

at the Rondout Reservoir inflow to the RWB Tunnel, Lippman 

Lake, 4 springs, and 19 wells, including 9 wells screened in 

unconsolidated deposits and 10 wells completed in bedrock. 

A description of the design of the monitoring network and 

methods of data collection and analysis of water-level 

fluctuations are included. The interpretive steps for estimating 

groundwater ages using atmospheric tracers are described, 

along with the distribution of the interpreted groundwater ages 

in selected wells.

The level of interpretation in this report is limited 

because additional information is required for a detailed 

assessment. Information on the geology, hydrogeology, and 

additional water-quality sample analysis in the study area is 

required to assess the sources of water in the aquifer system 

related to flooding.

Description of Study Area

The study area encompasses a 12-square mile (mi2) area 

in Wawarsing, N.Y., that is prone to frequent groundwater 

flooding. A sampling site at Rondout Reservoir at Lackawack 

(station 01366400; fig. 1), where reservoir water enters the 

RWB Tunnel portion of the Delaware Aqueduct was used to 

represent water from the RWB Tunnel. The Rondout Valley 

near the town of Wawarsing, Ulster County, N.Y., is part of 

the Port Jervis Trough, which is a deep, glaciated valley that 

extends about 100 mi southwestward from Kingston through 

Kerhonkson, N.Y., and continues into Pennsylvania. The 

Port Jervis Trough separates the Shawangunk Mountains to 

the east from the Catskill Front (eastern side of the Catskill 

Mountains) to the west (Reynolds, 2007). The valley in 

the study area is underlain by gravel, sand, silt, and clay of 

Pleistocene and Holocene age (Cadwell and others, 1989) and 

bedrock sequences of limestone, sandstone, and shale with 

substantial fracturing and faulting (Dibbell, 1944).

The population of Wawarsing was 13,157, according to 

the 2010 U.S. Census (U.S. Census Bureau, 2010), and land 

use is predominantly residential. Wawarsing lies to the west of 

the Shawangunk Mountains, which are the north-easternmost 

expression of the Valley and Ridge province of the central 

Appalachians. Land-surface altitudes range from about 

270 ft in the flood-prone area in Wawarsing to about 730 ft 

at the “mixing chamber” from the Rondout Reservoir to the 

Delaware Aqueduct (in this report, altitudes are referenced to 

the North American Vertical Datum of 1988, unless otherwise 

specified). The sampling network in Wawarsing and the 

Delaware Aqueduct water sampled in Lackawack are herein 

described as the “study area.”

The study area is underlain by unconsolidated deposits 

of variable thickness, including Pleistocene till and stratified 

drift, and Holocene alluvium. Much of the stratified drift is 

glacial lake silt and clay, which, along with the till, impedes 

infiltration and groundwater flow. The surrounding bedrock 

highlands rise about 150 ft to the west of the valley and about 

300 ft to the east.
Methods of Data Collection and Analysis 3

Previous Investigations

Several studies have focused on the NYC water-supply 

system and, more specifically, the RWB Tunnel. Merguerian 

(2000) described the history of the NYC water-supply 

system. Stumm and others (2012) studied the hydrologic 

effects of temporary shutdowns of the RWB Tunnel on the 

groundwater-flow system in Wawarsing. A drainage study 

(Chadd Hodgkinson, Malcolm Pirnie, written commun., 

2009) indicated that higher than average rainfall and poor 

drainage contributed to flooding of streets and basements in 

the study area.

The surficial and bedrock geology of the study area 

is described in several published reports. Drilling logs for 

wells in the study area were compiled by Frimpter (1970), 

who later characterized the hydrogeologic units in the study 

area (Frimpter, 1972). Reynolds (2007) mapped the surficial 

geology of the southern part of the study area and described 

the major unconsolidated units. Berkey (1911) described the 

unconsolidated deposits, bedrock geology, and possible faults 

within the Rondout Valley. Dibbell (1944) compiled the construction, geology, and hydrology of the RWB Tunnel within 

the study area. Fluhr (1950, 1953) described the results of 

exploration drilling by the NYCDEP in the study area. 

Methods of Data Collection and 

Analysis

The design of the sampling network of surface water, 

springs, monitoring wells, and supply wells; the water-quality 

sampling and analyses; age dating of groundwater; methods 

of quality assurance; and data interpretation are described in 

this section.

Design of Monitoring Network

The monitoring network includes sites for water-level 

measurements and water-quality sampling. The water-level 

monitoring network is discussed in detail by Stumm and 

others (2012) (fig. 2, table 1); water levels were measured 

at 31 sites to help determine the potentiometric surface and 

direction of groundwater flow (Stumm and others, 2012). Most 

of the wells in the monitoring network are used for private or 

public water supply, but monitoring wells were specifically 

drilled in the unconsolidated deposits during 2009–10 to 

monitor water levels and for potential water-quality sampling 

(Stumm and others, 2012). 

Water-quality monitoring includes surface-water sites 

(Rondout Reservoir, Lippman Lake), supply and monitoring wells, and springs (table 1, figs. 1 and 2). The springs 

include two basement sites associated with flooding (U1665 

and U1666), in addition to other springs (U1667, U1668) or 

well points installed at springs or “spring wells” (U1632 and 

U1633) in the hills to the east. The sampled wells include 

both monitoring and domestic and public supply wells in the 

unconsolidated aquifer and domestic and public supply wells 

in fractured bedrock.

Collection and Analysis of Water Samples

Water-quality samples were collected during conditions 

in which (1) basements were flooding in the Wawarsing 

areas and the water tunnel was under typical high-pressure 

conditions, (2) basements were not flooding and the water 

tunnel was under typical high-pressure conditions, and 

(3) basements were not flooding and the water tunnel was 

depressurized for repair work. Sites were sampled for an 

extensive list of constituents, including major ions and trace 

elements, dissolved gases, age tracers, and stable isotopes 

(tables 2–5). Surface-water bodies generally were not 

analyzed for dissolved gases, chlorofluorocarbons (CFCs), 

or sulfur hexafluoride (SF6

), which were used to estimate 

groundwater age, because they are sensitive to atmospheric 

interaction; however, these constituents were analyzed in 

some cases to provide source end members for mixing. Field 

characteristics, which include water temperature, pH, and 

specific conductance, were measured during sample collection 

in accordance with USGS procedures described by Koterba 

and others (1995).

Water was sampled according to protocols by Koterba 

and others (1995). Wells were purged, and field measurements of temperature, specific conductance, pH, turbidity, and 

dissolved oxygen (DO) concentrations were monitored until 

stable. Concentrations of total dissolved sulfides (H2

S plus 

HS-

, herein referred to as “H2S”) and low concentrations of 

DO (less than 1 milligram per liter (mg/L)) were measured 

onsite using colorimetric procedures (HACH Company, 2002). 

Water samples collected for analyses of major ions, trace 

elements, nutrients, and stable isotope ratios for 87Sr/86Sr, δ34S 

of SO4

2-, and δ13C of dissolved inorganic carbon (DIC) were 

filtered with a 0.45-micrometer (μm) inline filter. For water 

with low concentrations of SO4

2-, samples were collected on 

an anion-exchange resin column (Carmody and others, 1998). 

Water samples for δ13C of DIC analysis were collected in 

40 milliliter (mL) glass vials, which were preserved with 5 to 

10 milligrams (mg) of copper sulfate and sealed with a Teflon/

silicon septa cap.

Water samples to be analyzed for dissolved gases were 

collected in 160-mL septum bottles (sealed in a large beaker 

under flow of evacuated well water). Dissolved gases (N2

, Ar, 

CO2

, CH4, and O2) were analyzed by gas chromatography after 

extraction from sample headspaces (Busenberg and others, 

1998). The resulting data were used to define recharge temperatures for age dating because the solubility of atmospheric 

tracers varies as a function of temperature and for determining 

concentrations of excess air. Excess air consists of air trapped 

in pores that dissolves in groundwater, typically after a rapid 

rise in the water table. Recharge temperatures were calculated 
4 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

EXPLANATION

Delaware Aqueduct/Roundout–West 

 Branch Tunnel 

Surface-water site

01366400

76°

42°

41°

Cannonsville

Reservoir

Pepacton

Reservoir

Neversink

Reservoir

SULLIVAN

COUNTY

 DELAWARE

COUNTY

Port Jervis

PENNSYLVANIA

NEW YORK

Area of

detail

Base from U.S. Geological Survey Digital Data 1:100,000 series

Lambert Conformal Conic Projection

North American Datum of 1983

0

10

10

20

20

0 30 40

Figure 1. Wawarsing study area, including Port Jervis Trough (Kingston to Port Jervis), four reservoirs (Cannonsville, Pepacton, Neversink, 

and Rondout), Delaware Aqueduct, Roundout Reservoir sampling site 01366400 at the influent to Rondout–West Branch Tunnel, and Kensico 

Reservoir, in Westchester County, New York.
Methods of Data Collection and Analysis 5

74°

Central Park

Neversink Rondout

Reservoir

Kensico

Reservoir

P O R T

J E R V I S

T

R

O

U

G

H

Wawarsing

study area

Roseton

ULSTER

COUNTY

ULLIVAN

ORANGE

COUNTY

WESTCHESTER

COUNTY

ROCKLAND

COUNTY

DUTCHESS

COUNTY

PUTNAM

COUNTY

Kingston

NEW JERSEY

CONNECTICUT

MASSACHUSETTS

NEW YORK

01366400

30 40 50 MILES

50 KILOMETERS

Figure 1. Wawarsing study area, including Port Jervis Trough (Kingston to Port Jervis), four reservoirs (Cannonsville, Pepacton, Neversink, 

and Rondout), Delaware Aqueduct, Roundout Reservoir sampling site 01366400 at the influent to Rondout–West Branch Tunnel, and Kensico 

Reservoir, in Westchester County, New York.—Continued
6 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

#

U1628

U1625

U1645 U1629

U1644

U1626

U1627

U1663

U1637

U1641

U1670

U1673

414550074211101

Lippman Lake

effluent

U1632

U7017

U1665

U1666

U1668

U1651

U1624

U1636

U1649

U1661 U1655

U1648

U1642

U1656 U1638

U1646

U1652

U1657

U1660 U1654

U1639

U1635

U1658

01366807

U1664

U1674

U1672

U1634

U1669

U1671

Ellenville

STATE

ROUTE

2 0 9

H A M L E T B O U N D A R Y

Napanoch Port Ben Road

Honk Lake

Lippman

 Park Lake

41°

46'

41°

44'

74°22'

Base from U.S. Geological Survey Digital Data 1:100,000 series

Lambert Conformal Conic Projection

North American Datum of 1983

Figure 2. Monitoring sites at a lake (Lippman Lake), springs, unconsolidated monitoring and supply wells, and bedrock supply wells in 

Wawarsing, Ulster County, New York. (Location is shown in figure 1)
Methods of Data Collection and Analysis 7

EXPLANATION

U1638 Unconsolidated domestic supply well and identifier

Unconsolidated monitoring well and identifier U1636

Unconsolidated public supply well and identifier U1673

Bedrock domestic supply well and identifier U1647

Bedrock public supply well and identifier U1640

Spring or well installed at spring. 

U1629

Surface-water site and identifier 01366807

U1628

U1647

U1631

U3772

U1633

U1667

U1653

U1044

U1630

U1643

U1650

U1640

U1659

U1662

U4862

Kerhonkson

FOORDMOR E RO A D

ROUTE 44

Rondout

Cre e k

RONDOUT - WEST BRANCH TUNNEL

74°20' 74°18'

0 0.5 1 MILES

0 0.5 1 KILOMETERS

Identifier in red denotes site that was sampled 

 for water quality

Figure 2. Monitoring sites at a lake (Lippman Lake), springs, unconsolidated monitoring and supply wells, and bedrock supply wells in 

Wawarsing, Ulster County, New York. (Location is shown in figure 1)—Continued
8 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Table 1. Data on the sampling-site locations and construction of wells in the Wawarsing study area, and for the Rondout Reservoir at 

the influent to the Rondout–West Branch Tunnel in Lackawack, Ulster County, New York, 2009–11.

[NAVD 88, North American Vertical Datum of 1988; DSW, domestic supply well; RWB, Rondout–West Branch Tunnel; --, no data; NA, not applicable; 

MW, monitoring well; CSW, community supply well; NCSW, non-community supply well; SPR, spring; SW, surface water; datum of gage is North American 

Vertical Datum of 1988]

Well 

identifier

Well 

or site 

type

Depth 

(feet)

Land surface altitude 

(feet above 

NAVD 88)

Aquiferscreened 

well type

Summary description

U1625 DSW 275 278.4 Bedrock Flowing artesian well 1,820 feet from the RWB tunnel, extremely high 

transmissivity; large, rapid water-level response to tunnel.

U1626 DSW 10 275.7 Unconsolidated Located 1,460 feet from the RWB tunnel. The hydrograph at this well 

responds well to rainfall events and also to tunnel leakage.

U1627 DSW 15 279.3 Unconsolidated Responds well to rainfall events and also to tunnel leakage; tunnel 

(1,460 feet away) leakage inflows were estimated to have caused a 

0.5 to 1 foot increase in water levels.

U1628 DSW 200 275.7 Bedrock Near the tunnel trace and appears to be drilled within the Esopus Shale.

U1629 NCSW 118 300.1 Bedrock Located 945 feet from RWB tunnel; moderately transmissive fracture network; with tunnel depressurization, water levels at U1628 

dropped 5 to 6 feet, with delay of 48 hours.

U1630 DSW -- 266.1 Bedrock Artesian flowing domestic bedrock well in the north-central part of the 

valley, where an upward flow gradient of 6.8 feet was recorded.

U1631 DSW -- 262.5 Bedrock Flowing artesian well about 1,820 feet from the RWB tunnel; groundwater discharges from well at about 70 gallons per minute.

U1632 MW -- -- Unconsolidated These spring wells discharge from the upper slopes of a hilly deltaic 

deposit during seasonal (spring) periods of high precipitation and 

appear to result from a perched aquifer.

U1633 MW -- -- Unconsolidated

U1667 SPR NA -- --

U1668 SPR NA -- --

U1637 MW 27 264.5 Unconsolidated Screened in fine-grained material, low yield; depth to bedrock about 

U1641 MW 134 264.5 Unconsolidated 310 feet.

U1644 DSW -- 268.4 Bedrock Hydraulic head values much lower than in nearby bedrock wells; 

probably owing to less transmissive rock. 

U1645 DSW -- 288.2 Bedrock Located along the trace of the aqueduct, trends along a line perpendicular to the strike of the bedrock units; an area of lowest water-level 

response to tunnel influence may coincide with the Esopus Shale. 

Water-level changes during the shutdowns were only 1.5 feet.

U1647 NCSW -- 279.1 Bedrock One of the farthest measured wells (7,100 feet from the RWB tunnel) 

with an indicated tunnel leakage response.

U1663 MW 47 275.2 Unconsolidated Screened in fine grained material, low yield.

U1665 SPR NA 280 -- Water flows upward through basement cracks during flooding.

U1666 SPR NA 280 -- Water flows upward through basement cracks during flooding.

U1670 CSW 180 86.0 Unconsolidated Located 0.9 mile southwest of the tunnel trace, both wells screened 

in overburden, just above bedrock; well 2 has a better yield, with 

double the specific capacity of well 1; underlying bedrock likely 

Shawungunk Formation.

U1673 CSW 180 86.5 Unconsolidated

U3772 DSW 283 -- Bedrock Flowing artesian well northeast of the trace (possibly in the Hudson 

River Formation or Shawangunk Formation).

U7017 DSW -- -- Bedrock

Lippman Lake 

effluent

SW NA 299.2 NA Runoff from the lake discharges to a culvert during periods of high lake 

stage. The lake receives runoff from several small streams that flow 

from the adjacent hills.

013664001 SW NA 840 NA Sampled at the influent to the RWB tunnel.

1

Sample generally collected from sample port at 730-feet altitude.
Methods of Data Collection and Analysis 9

Table 2. Classes of water-quality chemical characteristics and constituents measured in water samples from a lake, springs, and 

wells in the Wawarsing study area, and for the Rondout Reservoir at the influent to the Rondout–West Branch Tunnel in Lackawack, 

Ulster County, New York, 2009–11.

[Water-quality field parameters: temperature, pH, specific conductance, dissolved oxygen, dissolved sulfides, alkalinity; O, oxygen; H, hydrogen; C, carbon; 

87Sr/86Sr, stable isotope ratio of strontium-87 to strontium-86; δ, delta; δ2

H (or “δD”), stable isotope ratio of hydrogen-2 to hydrogen-1; δ18O, stable isotope 

ratio of oxygen-18 to oxygen-16, relative to Vienna Standard Mean Ocean Water standard; δ34S of SO4

2-, stable isotope ratio of sulfur-34 to sulfur-32 of sulfate 

relative to the Vienna Canyon Diablo Troilite standard; δ13C in DIC, stable isotope ratio of C-13 to C-12 in dissolved inorganic carbon relative to the Vienna 

Pee Dee Belemnite standard; CFCs, chlorofluorocarbons; analyses done by the U.S. Geological Survey (USGS) National Water Quality Laboratory, unless 

otherwise indicated]

Water-quality field parameters

Major inorganic constituents and nutrients

Trace elements

87Sr/86Sr isotopes1

δ18O and δ2H (δD) isotopes2

δ34S of SO4

2- isotopes2

δ13C isotopes2

Dissolved gases3

CFCs4

Sulfur hexafluoride4 (SF6)

3

H (tritium)5

1

Analyzed at the USGS Isotope Laboratory, Menlo Park, Calif.

2

Analyzed at the USGS Reston Stable Isotope Laboratory, Reston, Va.

3

Analyzed at the USGS Dissolved Gas Laboratory, Reston, Va.

4

Analyzed at the USGS CFC Laboratory, Reston, Va.

5

Analyzed at the USGS Isotope Tracer Laboratory, Menlo Park, Calif.

to the calculation of SF6 or CFC concentrations. The percent 

uncertainty in sample concentrations was below 3 percent.

The 3H in water was measured at the 3H Laboratory, 

University of Miami, by internal gas proportional counting of 

H2

-gas made from the water samples. The 3H that was released 

into the atmosphere between 1952 and 1963 during nuclear 

weapons tests provides a tracer for rainwater, which allows 

dates of recharge to be estimated. Although 3

H concentrations 

are approaching that of natural atmospheric production (6 to 

15 pCi/L), they remain high enough to use in this analysis. 

The 3

H related to weapons testing can be used to infer some 

aspects of groundwater age; at the very least, water can be 

classified as being recharged before or after 1953.

The CFC samples were collected by inserting the end of 

the discharge tubing into the bottom of the bottle, allowing at 

least 2 liters (L) to overflow into a 2-L beaker, then capping 

the 125-mL glass bottles with special foil-lined caps under 

water within the beaker. Groundwater samples for SF6

were collected by placing the sampling-discharge line in 

the bottom of the bottle and displacing the air in the bottle 

with groundwater. After approximately 2 L of overflow, the 

sampling line was removed. The bottles were tightly sealed 

without headspace using conical screw caps and wrapped with 

electrical tape.

from N2

 and Ar gas concentrations in samples. N2 concentrations can be affected by denitrification under denitrifying 

conditions, but excess N2

 was not present. 

Groundwater ages were estimated from concentrations of 

tritium (3

H), chlorofluorocarbons (CFCs, including CFC-11, 

CFC-12, and CFC-113), and sulfur hexafluoride (SF6

) tracers. Anthropogenic activities, such as industrial processes and 

atmospheric testing of thermonuclear devices, released 3

H, 

SF6

, and CFCs into the atmosphere in small but measurable 

concentrations. Precipitation that incorporates these gases 

from the atmosphere infiltrates into the ground and carries the 

particular chemical or isotopic signature of the atmospheric 

conditions at the time of recharge. These dating methods 

assume that gas exchange between the unsaturated zone and 

the atmosphere is fast but that shallow groundwater remains 

closed to gas exchange after recharge (Schlosser and others, 

1989; Plummer and Busenberg, 1999; Busenberg and 

Plummer, 2000). Where possible, at least two age-dating indicators were measured at sampling sites. Apparent ages were 

estimated by assuming that piston flow prevails in the aquifer 

system. Age-tracer samples were collected without headspace, 

although bubbles of H2

S formed in several samples from bedrock wells. If an H2

S bubble formed in the sample bottle, the 

headspace volume was measured and a correction was applied 
10 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Concentrations of trichlorofluoromethane (CFC-11), 

dichlorodifluoromethane (CFC-12), and 1,1,2-trichlorotrifluoroethane (CFC-113) in water were determined at the USGS 

CFC Laboratory in Reston, Virginia, with a detection limit 

of about 0.3 picomole per kilogram using purge and trap, 

gas-chromatographic techniques with electron-capture detector (GC-ECD) (Bullister, 1984; Bullister and Weiss, 1988; 

Busenberg and Plummer, 1992). The CFC-dating technique is 

described in Busenberg and Plummer (1992). Samples were 

analyzed for SF6 at the USGS CFC Laboratory using procedures described by Busenberg and Plummer (2000).

Stable isotopes were analyzed using several different 

methods. Analyses of the stable-isotope ratios oxygen-18 to 

oxygen-16 (δ18O), hydrogen-2 to hydrogen-1 (δ2H), δ34S of 

SO4

2-, and δ13C of DIC were done at the USGS Stable Isotope 

Laboratory in Reston, Virginia. A hydrogen equilibration 

method was used for δ2H analysis (Coplen and others, 1991), 

and the CO2 equilibration technique (Epstein and Mayeda, 

1953) was used for analysis of δ18O. The 2-sigma analytical 

uncertainties for δ2H and δ18O values are 2 and 0.2 per mil, 

respectively. The δ34S of SO4

2− was analyzed for BaSO4

precipitates using procedures described in Carmody and others 

(1998). Results are reported in per mil relative to the Vienna 

Canyon Diablo Troilite (VCDT) standard. The uncertainty 

associated with δ34S values is ±0.2 per mil. Water samples 

were analyzed for δ13C using mass-spectrometry techniques at 

the University of Waterloo Environmental Isotope Laboratory, 

Waterloo, Ontario, Canada, and are reported relative to the 

Vienna Pee Dee Belemnite (VPDB) standard. The uncertainty 

associated with the δ13C values is ±0.2 per mil. Ratios 

of 87Sr/86Sr were determined by thermal ionization mass 

spectrometry as described by Bullen and others (1997).

Quality Assurance

Field probes were cleaned and calibrated with standard 

solutions and checked periodically with independent field and 

laboratory probes. Field quality-control procedures included 

the collection and analysis of replicate samples, which 

provided information on the variability of analytical results 

caused by sample collection, processing, and analysis. The 

charge balances for major ion analyses generally were within 

±5 percent, although 9 of the 40 samples that were analyzed 

for major and trace ions had greater imbalances (table 3, in 

back of report) and could result from (1) ions not included in 

the analyses, (2) error in laboratory analyses, and (or) (3) error 

caused by exsolution (degassing) or dissolution of carbon 

dioxide before sample analysis.

Hydrogeologic Setting

The geology and hydrology of the bedrock and unconsolidated deposits are discussed in the following section.

Geology

Bedrock

A complex series of fractured sedimentary bedrock units 

of Silurian and Devonian age underlie the unconsolidated 

deposits in the study area. The bedrock generally strikes 

northeast and dips about 45 degrees to the northwest. The 

bedrock units as delineated by Berkey and Fluhr (1936) 

and Dibbell (1944) include the Marcellus Shale, Onondaga 

Limestone, Esopus-Schoharie Shale, Helderberg Limestones 

(Port Ewen-Becraft, New Scotland, Coeymans), Manlius 

Limestone, Binnewater Limestone and Sandstone, High 

Falls Shale and Limestone, Wawarsing Wedge complex, 

Shawangunk Sandstone, and Hudson River Shale. The 

Marcellus Shale is estimated to have relatively high gasproduction potential and is being considered for extraction 

in parts of New York, as well as Ohio, Maryland, and large 

parts of Pennsylvania and eastern West Virginia (Kargbo and 

others, 2010). The Shawangunk Formation, which caps the 

Shawangunk Mountains to the east, contacts the overlying 

Wawarsing Wedge to the west and the underlying Hudson 

River Shale to the east. Dibbell (1944) describes the bedrock 

sequences as having sections with substantial fracturing, and 

faulting in the subsurface below the study area. Many of these 

fracture and fault zones produced groundwater in thousands 

of gallons per minute during construction of the RWB Tunnel 

(figs. 3A and B).

Leakage of water from the RWB Tunnel appears to be 

from cracks in the liner allowing pressurized tunnel water 

to flow behind and (or) through the liner where transmissive 

voids may exist, including solution cavities in limestone, as 

well as through fractures, faults, and geologic contacts. Sustained leakage of pressurized tunnel water through limestone 

that contains dissolution features could induce further dissolution of the limestone surrounding the tunnel liner. The 

Onondaga Limestone was described as being cavernous in 

many places and members of the Helderberg and Manlius 

Limestones exhibited a tendency to develop cavernous structures (Berkey and Fluhr, 1936). Transmissive fractures, faults, 

and bedrock contacts eventually crop out in the subsurface 

where the unconsolidated deposits may impede or transmit the 

pressurized RWB Tunnel leakage.

Some of the minerals in the fractured bedrock aquifer 

system are particularly pertinent to water-chemistry 

constituents, such as H2S, CH4, SO4

2-, Sr, and several stable 

isotopes. For example, evaporites formed during the arid 

conditions in the late Silurian and the Silurian sedimentary 

sequence probably functioned as a paleoaquifer (Kesler 

and others, 1997). Sulfur (S) isotope compositions indicate 

that the lower part of the paleoaquifer contained reduced S 

formed by thermochemical reduction, whereas the upper part 

of the paleoaquifer contained reduced S formed by bacterial 

reduction of SO4

2- derived from overlying Salina Group 

evaporites. These constraints, along with Na-Cl-Br leachate 
Hydrogeologic Setting 11

data, indicate that Mississippi Valley Type mineralization in 

the Lockport Dolomite formed when rising, metal-bearing 

brines mixed with descending, sulfur-bearing brines from the 

Salina Group above (Kesler and others, 1997). Vein deposits 

of zinc, lead, and copper sulfides are present to the east, on the 

west slope of the Shawangunk Mountains (Heusser, 1976), in 

a northeast-trending belt 24 mi long, extending from Guymard 

to Ellenville, N.Y. (Wilbur and others, 1990). These deposits 

mark the eastern margin of the evaporite-bearing Silurian 

sedimentary basin and were observed during completion of the 

Delaware Aqueduct (Bird, 1944).

Unconsolidated Deposits

The valley in the study area is underlain by surficial 

deposits of gravel, sand, silt, and clay, and include Pleistocene 

glacial stratified and till deposits, and Holocene alluvium 

deposits, which are present primarily in stream channels. The 

major unconsolidated hydrogeologic units consist of till, icecontact stratified drift, outwash, glacial lake clays, recent alluvium, and colluvium. Reynolds (2007) and Frimpter (1972) 

described a sand and gravel aquifer buried beneath glacial lake 

sediments. Geologic data from 14 USGS-drilled monitoring 

wells within the study area indicate highly variable deposits 

ranging from sand and gravel to silt and clay and lacustrine 

clay deposits that exceed 140 ft in thickness in some areas 

(Frederick Stumm, U.S. Geological Survey, written commun., 

2010). Preliminary analysis of unpublished USGS passive 

seismic surveys and deep electromagnetic geophysical surveys 

of the study area indicate that the bedrock contact is undulating with areas of deep erosional troughs. These deep troughs 

are northeast-southwest trending and extend more than 300 ft 

below land surface. 

Hydrology

Randall (1996) studied the precipitation variations in 

upstate New York and determined that the Wawarsing study 

area averaged about 44 inches (in.) of precipitation annually 

during 1951–80. This study is consistent with the long-term 

daily precipitation records recorded by the National Weather 

Service (NWS) at Central Park in New York City (National 

Oceanic and Atmospheric Administration, 2010), and indicates only slight variations owing to localized storms. Annual 

precipitation exceeded the long-term mean every year during 

2002–10. The increase in precipitation has caused increased 

groundwater levels and contributed to surface flooding when 

the rate of precipitation exceeded drainage from roadways or 

recharge into surficial deposits (Stumm and others, 2012).

Groundwater generally flows from the surrounding hills 

east and west of the valley and from southwest of the valley toward the central and ultimately northeastern part of the 

valley. Hydrographs from wells screened in unconsolidated 

deposits indicate a direct correlation to precipitation but also 

some effects caused by tunnel leakages from underlying 

bedrock (Stumm and others, 2012). Analysis of the vertical gradients between the deeper and shallower parts of the 

unconsolidated aquifer indicate an upward-flow gradient, 

particularly in the central parts of the valley where the water 

table discharges to Rondout Creek and the deposits are thickest (Stumm and others, 2012).

For bedrock wells, the highest water levels were 

recorded in March and April of 2009 and 2010 during periods 

of elevated precipitation (Stumm and others, 2012). The 

bedrock potentiometric surface was higher locally in the area 

along State Route 209 as a result of tunnel leakage (Stumm 

and others, 2012). Most bedrock wells affected by tunnel 

leakage had upward-flow gradients from the bedrock to the 

unconsolidated aquifer. The head differential between the 

bedrock and unconsolidated aquifers at wells U1627 and 

U1625 was 10.6 ft, and the flow gradient direction was upward 

(Stumm and others, 2012).

The majority of homes in Wawarsing rely upon domesticsupply wells in the unconsolidated and bedrock aquifers. 

Major municipal-water users in this area include the Village 

of Ellenville (4,400) and the Eastern New York Correctional 

Facility (700), totaling about 5,000 municipal groundwater 

users (New York State Department of Health, 1982). The 

transmissivity of the aquifer near Ellenville appears to be very 

high, as evidenced by a 39-ft deep supply well for the village 

of Ellenville that initially had a pumping rate of 1,000 gal/min 

(Frimpter, 1972).

Water-Quality Monitoring Sites

Water-quality monitoring sites sampled in Wawarsing 

include four springs, seven wells screened in unconsolidated 

deposits, and six wells in bedrock, in addition to the lake site 

at Lippman Park. Manual measurements of groundwater levels 

were completed monthly, and levels at selected wells were 

recorded hourly with pressure transducers and data loggers, as 

described in Stumm and others (2012). Groundwater temperatures in wells U1625, U1630, U1649, and U1651 were the 

lowest among the monitored bedrock wells and are consistent 

with the leakage of colder tunnel water into the surrounding fractured-bedrock groundwater-flow system along highly 

transmissive sections (Stumm and others, 2012). Bedrock 

wells with the coldest groundwater temperatures were the 

same wells that had the largest water-level changes and shortest delay times to tunnel influences.

Rondout Reservoir and the Rondout–West 

Branch Water Tunnel

Rondout Reservoir water was sampled at the influent 

to the RWB Tunnel, which carries water from the Rondout 

Reservoir to the Kensico Reservoir and then on to NYC 

(fig. 1). Sample analysis of this water was used to represent 

water chemistry in the tunnel. Water in the Rondout Reservoir 

results from precipitation in the contributing Delaware and 
12 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Honk Lake

Lippman

 Park Lake

U1651

U1624

U1636

U1649

U1661 U1655

U1648

U1642

U1656

U1638

U1646

U1652

U1657

U1660

U1654

U1639

U1635

U1658

01366807

U1664

U1674

U1672

U1634

U1669

U1671

U1628

U1625

U1645

U1629

U1644

U1626

U1627

U1663

U1637

U1641

U1670

U1673

414550074211101

Lippman Lake

effluent

U1632

U7017

U1665

U1666

U1668

STATE

ROUTE

2 0 9

Steel interliner

Port Ben Road

Ellenville

Napanoch

Rondout–West Branch

H A M L E T B O U N D A R Y

74°22'

41°

46'

41°

44'

Base from U.S. Geological Survey Digital Data 1:100,000 series

Lambert Conformal Conic Projection

North American Datum of 1983

Figure 3. A. Locations of wells and surface-water sites; Rondout–West Branch Tunnel geology; and water-inflow rates documented during 

tunnel construction in the Wawarsing study area, Ulster County, New York (Location is shown in figure 1; LS, limestone; SS, sandstone; 

SH, shale). 
Hydrogeologic Setting 13

Rondout

Cre e k

U1653

U1044

U1630

U1636

U1643

U1650

U1640

U1659

U1662

U4862 U1647

U1631

U3772

U1633

U1667

FOORDMORE RD

Reinforced section

Kerhonkson

74°20' 74°18'

0 0.5 1 MILES

0 0.5 1 KILOMETERS

RONDOUT–WEST BRANCH TUNNEL

Water inflow, in gallons per minute

Shale (Ashokan)

Shale (Hamilton-Marcellus)

Limestone (Onandaga)

Shale (Esopus-Schoharie)

Shaly limestone (Port Ewen)

Limestone (Manlius)

LS/SS/SH (Binnewater)

SH/LS (High Falls)

Limestone (Wawarsing Wedge)

Sandstone (Shawangunk)

Shale (Hudson River)

Limestone (Coeymans)

Limestone (New Scotland)

2.000000–10.000000

10.000001–100.000000

100.000001–1000.000000

9,100

Line of section

EXPLANATION

Limestone (Becraft)

Rock type/formation

U1629 Identifier in red denotes site that was 

 sampled for water quality

Surface-water site and identifier

U1640 Bedrock public supply well and identifier

U1647 Bedrock domestic supply well and identifier

U1673 Unconsolidated public supply well and identifier

U1638 Unconsolidated domestic supply well and identifier

U1636 Unconsolidated monitoring well and identifier

Figure 3. A. Locations of wells and surface-water sites; Rondout–West Branch Tunnel geology; and water-inflow rates documented during 

tunnel construction in the Wawarsing study area, Ulster County, New York (Location is shown in figure 1; LS, limestone; SS, sandstone; 

SH, shale).—Continued
14 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Figure 3. B. Geology observed during New York City Board of Water Supply test borings and Rondout–West Branch Tunnel construction 

from A to A’ within the study area, Town of Wawarsing, Ulster County, New York. (Location is shown in figure 3A) (The Helderberg Group 

has been divided into the Port Ewen, Becraft, New Scotland, and Coeymans Formations; vertical coordinate information is referenced to 

the North American Vertical Datum of 1988 (NAVD 88). (Modified from Berkey and Fluhr, 1936).
Hydrogeologic Setting 15

Figure 3. B. Geology observed during New York City Board of Water Supply test borings and Rondout–West Branch Tunnel construction 

from A to A’ within the study area, Town of Wawarsing, Ulster County, New York. (Location is shown in figure 3A) (The Helderberg Group 

has been divided into the Port Ewen, Becraft, New Scotland, and Coeymans Formations; vertical coordinate information is referenced to 

the North American Vertical Datum of 1988 (NAVD 88). (Modified from Berkey and Fluhr, 1936).—Continued
16 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Catskill watersheds. The Rondout Reservoir is located 75 mi 

northwest of NYC in the Catskill Mountains between the 

towns of Wawarsing in Ulster County and Neversink in 

Sullivan County. The reservoir is the central collection point 

for the Delaware System and provides about one-half of the 

daily consumption for NYC. 

The Rondout Reservoir is 6.5 mi long and 3.2 mi2 in 

area and reaches a maximum depth of 175 ft near the dam; 

the mean depth is 73.8 ft, and the altitude is 840 ft above 

NAVD 88 (Effler and others, 2001). The Rondout Reservoir 

holds 49.6 billion gallons, which comes from the 95-mi2 

Rondout Creek watershed, as well as from the Cannonsville, 

Neversink, and Pepacton Reservoirs via the Delaware and 

Neversink Tunnels. Because those three reservoirs are in the 

Delaware River watershed, Rondout is considered by the 

city’s Department of Environmental Protection to be part of 

the Delaware System despite being entirely within the Hudson 

River watershed. Rondout is circumscribed by State Routes 55 

and 55A, but access to the actual reservoir is tightly restricted. 

Specific conductance in the Rondout Reservoir generally 

is lower than in the Pepacton and Cannonsville Reservoirs, but 

higher than in the Neversink Reservoir (Owens, 1998; Effler 

and others, 2001). Specific conductance and temperature in the 

Rondout Reservoir did not vary substantially in lateral directions (Effler and O’Donnell, 2001). The Rondout Reservoir 

undergoes thermal stratification during summer, although not 

extensively because of the large contributions of cold water 

received from the upstream reservoirs. The Rondout Reservoir 

has a drawdown of 35 ft (10.8 meters) and a flushing rate of 

6.8 times per year (Effler and others, 2001).

Hydrologic Effects of Temporary Rondout–West 

Branch Water Tunnel Shutdowns

The NYCDEP shut down the RWB Tunnel on four 

separate occasions from October 2008 to December 2010 

(Stumm and others, 2012) and three times during the period 

of water-quality sampling, December 2009 to April 2010. 

The four shutdowns occurred (1) October 25–November 26, 

2008, (2) November 5–19, 2009, (3) December 4–16, 2009, 

and (4) January 13–26, 2010. During each of the shutdowns, 

the tunnel pressure was slowly reduced from about 600 to 

about 75 ft above NAVD 88 over a period of 34 to 56 hours, 

as measured in a nearby tunnel shaft. The re-pressurization 

process was accomplished in the same manner, by increasing 

the pressure in the RWB Tunnel from about 75 to about 600 ft 

above NAVD 88, over a period of 43 to 54 hours. 

A number of wells screened in unconsolidated deposits 

and in bedrock in Wawarsing indicated water-level changes 

in response to tunnel pressure (Stumm and others, 2012). The 

location of unconsolidated aquifer wells with measureable 

changes to tunnel leakage correlated with those in the bedrock. 

Water levels in the bedrock changed as much as 12 ft within 

0.5 hour during tunnel shutdowns, although the majority of 

bedrock wells influenced by tunnel leakage indicated lag times 

of 21 to 33 hours. RWB Tunnel leakage has been documented 

to enter the bedrock units adjacent to the tunnel and cause 

increases in the bedrock water levels by as much as 10.5 ft 

(Stumm and others, 2012). Transmissive fractures in the bedrock near the contact between the unconsolidated and bedrock 

aquifers can transmit this increased pressure to the overlying 

unconsolidated aquifer.

Water-level changes in bedrock wells during the shutdowns ranged from 12 ft at U1625 to 1.5 ft at U1645, and well 

U1629 indicated no change (Stumm and others, 2012). The 

greater water-level responses in units on either side of these 

wells appear to correlate with the limestone units in contact 

with the shale (Stumm and others, 2012). Analysis of the 

hydrographs at U1625 during the tunnel shutdowns indicates 

the bedrock in this area responds within about 0.5 hour of tunnel depressurization or re-pressurization (fig. 11B in Stumm 

and others, 2012). The rapid response times to changes in 

tunnel pressure, the large water-level changes, and the considerable distance from the tunnel may indicate the existence 

of an interconnected cave or dissolution fracture system with 

large storage and transmissivity characteristics. Well U1647, 

located 7,100 ft from the RWB Tunnel, was one of the farthest 

measured wells with a tunnel-leakage response. Bedrock wells 

U1628 and U1631 had among the longest lag times: 48 and 

60 hours, respectively (Stumm and others, 2012). Well U1628 

is near the tunnel and appears to be drilled within the Esopus 

Shale, a fine-grained rock unit that could have limited transmissivity and connectivity (fig. 3).

Water levels in the unconsolidated deposits changed 

as much as 2.5 ft within 18 hours during tunnel shutdowns 

(Stumm and others, 2012). The location of wells in the unconsolidated aquifer with measurable changes caused by tunnel 

leakage correlated with those in the bedrock, including some 

at distances of 7,000 ft from the RWB Tunnel (Stumm and 

others, 2012). A hydrograph of well U1641 indicates a drop in 

water levels of 2 to 2.5 ft during each of the last three shutdowns. The tunnel-leakage influence lag time at this overburden well was only about 18 hours, indicating that the bedrock, 

which is about 170 ft deeper than well U1641, must consist of 

highly transmissive fractures that respond quickly to tunnelpressure changes (Stumm and others, 2012). Tunnel-leakage 

inflows at U1626 were estimated to have caused a 0.5 to 1 ft 

increase in water levels in the unconsolidated aquifer at this 

well (Stumm and others, 2012).

Water Sources and Chemistry

Anthropogenic and natural sources of water can be 

characterized based on water chemistry, age tracers, and stable 

isotopes. Data analysis included graphical plotting of concentrations of water-quality constituents and pertinent plots of 

constituent and isotope ratios. 
Water Sources and Chemistry 17

Sources of Water

Groundwater chemistry is primarily affected by 

atmospheric deposition; weathering of soil and aquifer 

material; and anthropogenic sources, such as road salt, 

septic-system leachate, leaking underground-storage tanks, 

landfills, chemical spills, and storm-water runoff from roads 

and parking lots. Several analysis tools were used to help 

distinguish (1) anthropogenic sources or pathways from 

natural ones and (2) surface water or shallow groundwater 

from deep groundwater, including Piper diagrams, scatterplots 

(not shown), saturation indexes for calcite and gypsum, 

stable isotopes, dissolved gases, and groundwater-age tracers. 

Differences in chemical signatures among the parts of the 

hydrologic system were used to improve the understanding of 

source waters and groundwater-flow patterns and pathways 

and can be used to assess mixing of the different source waters 

in samples.

Major Constituents and Nutrients

Major-ion concentrations in water samples collected 

during the study show differences depending on the sample 

type, depth, and location (table 3, in back of report). The 

Piper diagram (Piper, 1944) is used to show the clustering of 

samples by water type and the effects of aquifer weathering 

and anthropogenic activities on major-ion concentrations; 

samples are represented by the percentages of total cations 

and total anions, plotted on separate trilinear plots, and then 

projected onto a central diamond (fig. 4). 

The anion percentages in water samples from most 

unconsolidated aquifer wells and springs were greater in 

HCO3

-

 and carbonate (CO3

2

) than in SO4

2- and chloride compared to the bedrock well samples; the lower concentrations of 

HCO3

-

 in deep groundwater could result from the precipitation 

of calcite. Similarly, water samples from most unconsolidated 

aquifer wells and springs had a greater percentage of calcium 

(Ca) compared to other cations than did bedrock well samples. 

The exception was the water sample from U1625, which had 

high ratios of HCO3

 and Ca relative to other ions, and similar 

to other samples, such as unconsolidated aquifer well samples 

and surface-water samples (fig. 4). Water samples from 

bedrock wells generally had relatively high concentrations of 

SO4

2- compared to other anions; samples from two bedrock 

wells that did not have high concentrations of SO4

2- were 

reducing and had high concentrations of dissolved H2

S. High 

concentrations of SO4

2- are not uncommon in groundwater 

from the Silurian-Devonian bedrock, which is likely due to the 

presence of gypsum in the upper part of the Silurian sequence 

(Williams and Eckhardt, 1987).

Nitrate (NO3

-

) plus nitrite (NO2

-

) in water samples can 

be derived from several sources, including microbial decay of 

organic matter in soils, animal waste, septic-system leachate, 

synthetic fertilizers, and rainfall. Concentrations of NO3

-

 plus 

NO2

-

 ranged from less than the minimum reporting levels 

(MRLs) in water samples with reducing redox characteristics 

to 0.88 mg/L as N for a domestic well in a residential area 

with onsite septic-tank drainfields (table 3, in back of report). 

Concentrations of NO2

-

 were less than the MRL of 0.008 mg/L 

as N in all but two samples; therefore, NO3

-

 plus NO2

-

 is 

hereafter referred to as NO3

-

. The median concentration of 

NO3

-

 for wells in the study area was less than 0.5 mg/L as N, 

and samples at more than one-half of the sites were below 

the reporting level of 0.04 mg/L as N. Urban septic-system 

leachate and lawn fertilizer are the major sources of NO3

-

 in 

the study area and can affect shallow groundwater quality. 

Although NO3

-

 from septic systems does not appear to be 

a health concern, bacterial contamination of private-supply 

wells with Escherichia coli (E. coli) is a recurring problem in 

the Rondout Valley near the town of Wawarsing (J.T. Rodden, 

Jr., Ulster County Health Department, written commun., 

2009). The presence of E. coli in domestic well water is likely 

caused by the mobilization of septic-system leachate by the 

high water table associated with seasonal flooding.

Saturation indexes, which are represented by the 

logarithms of the ratios of the ion activity products to the 

solubility product constants, or log (IAP/Ksp), indicated that 

groundwater samples from bedrock wells were at or near 

saturation with respect to gaseous CO2

, quartz, calcite, and 

dolomite, and undersaturated with respect to gypsum and 

fluorite (table 3, in back of report). Groundwater samples 

from most bedrock wells generally were nearer to saturation 

of calcite and gypsum than groundwater samples from 

unconsolidated wells (fig. 5). The U1625 well sample that 

was collected at the RWB Tunnel during low-head pressure 

on December 14, 2009, shows similar chemistry to that of 

other bedrock wells; however, samples that were collected 

on June 24, 2009, and April 7, 2011, from well U1625 

under normal tunnel-pressure conditions, when the tunnel 

pressure was high, had chemistry that was similar to shallow 

groundwater or surface water (fig. 5). Similarly, the U1631 

well sample that was collected at the RWB Tunnel during 

low-head pressure on December 14, 2009, was supersaturated 

with respect to calcite, yet was undersaturated in the sample 

collected on September 16, 2009, when the tunnel pressure 

was high. These differences in bedrock groundwater chemistry 

between normal and depressurized tunnel conditions indicate 

that tunnel water does influence native groundwater under 

normally pressurized tunnel conditions.

Redox Conditions

Redox reactions affect many chemical processes in 

aquifers, including the concentrations of dissolved gases, such 

as O2

, N2, H2S, and CH4; speciation and mobility of naturally 

occurring elements, such as Fe, Mn, S, As, and U; and the 

transformation of anthropogenic compounds, such as NO3

-

, 

chloroform, and trichloroethylene. Redox conditions tend to 

proceed along a well-documented sequence of zones dominated by a single electron-accepting process. Water-quality 
18 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

EXPLANATION

Lippman Lake effluent

Rondout Reservoir, influent to Rondout–

 West Branch Tunnel (01366400)

Spring

Well, overburden and identifier

Well, bedrock and identifier

U1625

U1625

U1637

U1641

U1637

U1626

U1626

U1629

U1629

U1629

U1629

U1629

U1626

U1627

U1627

U1637

U1641

U1641

U1625

U1625

U1630

U1630

U1630

U1631

U1628

U1628

U1628

U1627

U1663

U1663

U1663

U1647

U1647

U1647

U1647

U1631

U1631

U1773

U1773

U1773

U1770

U1770

U1770

U1645

U1644

U1645

U1645

U1644

U1644

U7017

U3772

U7017

U3772

U3772 U7017

U1625

U1666

Wells likely in

Shawongunk Fm

U1666

U1666

U1665

U1665

U1665

Percent

Calcium

100

80

60

40

20

 0

 0

20

40

60

80

100

Magnesium

 0

20

40

60

80

100

Sodium plus potassium

Chloride

 0

20

40

60

80

100

100

80

60

40

20

 0

 Bicarbonate plus carbonate

100

80

60

40

20

 0

Sulfate

 0

20

40

60

80

100

Sulfate plus chloride

 0

20

40

60

80

100

Calcium plus magnesium

100

80

60

40

20

 0

100

80

60

40

20

 0

Percent

Percent

Figure 4. The percentage of total equivalents of major cations and anions in surface-water and groundwater samples collected from a 

lake, springs, and wells in Wawarsing and for the Rondout Reservoir at the influent to the Rondout–West Branch Tunnel in Lackawack, 

Ulster County, New York, 2009–11.
Water Sources and Chemistry 19

Lippman Lake

Interaction with bedrock

Shift in chemistry during low

 RWB Tunnel head pressure

Rondout Reservoir

Spring

Well, unconsolidated

Well, bedrock

Well, bedrock during low

 RWB Tunnel head pressure

Gypsum saturation index

Calcite saturation index

U-1626

U-1626

U-1627

U-1627

U-1637

U-1641 U-1641

U-1673

U-1670

U-1663

U-1666

U-1665

U-1665

U-1625

12/14/09.

U-1625

12/14/09

U-1625

U-1629

U-1644

U-1645

U-1628

U-1630

U-1630

U-3772

U-7017

U-1647

EXPLANATION

U-1631,

12/14/09

U-1631,

9/16/09

4/7/11

6/24/09

4/7/11

-5 -4 -3 -2 -1

-3

-4

-2

-1

0

1

Figure 5. Saturation indexes for calcite and gypsum in surface-water and groundwater samples collected from a lake, springs, and 

wells in the study area, Wawarsing, New York, and for the Rondout Reservoir at the influent to the Rondout–West Branch (RWB) Tunnel 

in Lackawack, Ulster County, New York, 2009–11.

data can be used to assess ambient-redox processes in 

groundwater systems (McMahon and Chapelle, 2007). DO 

produces more energy per mole of organic carbon oxidized 

than any other commonly available electron acceptor; thus, it 

is used preferentially by surface and subsurface microorganisms. Because groundwater systems can be isolated from the 

atmosphere, however, O2

 tends to be consumed along aquifer 

flow paths. Under anoxic conditions, the next most energetically favorable naturally available electron acceptor is NO3

-

, 

followed by manganese (IV) [Mn(IV)], ferric iron [Fe(III)], 

sulfate (SO4

2-), and finally carbon dioxide (CO2

). This order of 

preferential electron acceptor utilization—O2

 > NO3

-

 > Mn(IV) 

> Fe(III) > SO4

2- > CO2

—is referred to as the ecological succession of terminal electron-accepting processes (TEAPs). 

These predominant TEAPs, from more oxidizing to reducing, are O2

-reducing (also referred to as oxic in this report), 

NO3

-

-reducing, Mn-reducing, Fe-reducing, SO4

2--reducing, and 

methanogenic (containing methane or CH4

). Some common 

contaminants of groundwater systems, such as chlorinated 

ethenes, also may act as electron acceptors.

A redox classification scheme described by McMahon 

and Chapelle (2007) and modified by Chapelle and others 

(2009) uses various chemical indicator species to classify 

redox conditions in each groundwater sample. The scheme 

has been modified for this study based on available data 

for N2

, H2S, and CH4 (table 4, in back of report). In several 

instances, conflicting or overlapping indicators of redox 

conditions occur and are related to mixtures of water with 

different redox indicators but also may indicate disequilibrium 

among redox indicators; therefore, the term is used whereby 

Y/Z indicates waters with different redox ranging from most 

oxidized (Y) to most reduced (Z). CH4

 was present in water 

samples from bedrock wells, including high concentrations 

(greater than 1 mg/L) in samples from U1629, U1647, U7017, 
20 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

U3772, and U1644 (table 4, in back of report). The Devonian 

bedrock sequence includes the black shales of the Esopus and 

Marcellus Formations, which are organic rich, so the presence 

of CH4

 is not surprising.

Redox conditions in the study area ranged from oxic 

in surface water and most wells screened in unconsolidated 

deposits to reducing in those wells screened in poorly 

permeable unconsolidated deposits and in bedrock (table 4, 

in back of report). Bedrock wells typically have long, open 

sections that could have had water contributed from several 

fractures with different flow-path histories. For example, 

bedrock well U1631 had DO concentrations greater than 

1 mg/L, yet also had high concentrations of reduced species, 

including dissolved Fe, Mn, H2S, and CH4. CH4 is not included 

as a redox variable for the redox classification system used, 

but its presence in groundwater indicates a contribution of 

water with very reducing conditions. Most of the bedrock 

wells were reducing, with the exception of well U1625; 

concentrations of DO were greater than 2 mg/L in well 

U1625, but CH4

 was present in the second sample collected 

on December 14, 2009, during a tunnel shutdown (table 4, in 

back of report).

Trace Constituents

Concentrations of trace constituents, including Fe, Mn, 

As, Sr, Ba, B, Li, Ni, and Pb, were generally higher in water 

samples from bedrock wells than in water samples from wells 

screened in unconsolidated deposits, RWB Tunnel water, or 

Lippman Lake (table 5, in back of report). High concentrations 

of dissolved Mn and (or) Fe reflect anoxic conditions, and 

one or both exceeded U.S. Environmental Protection Agency 

secondary drinking-water standards of 50 micrograms per liter 

(μg/L) and 300 μg/L, respectively, at several wells (table 5, in 

back of report; U.S. Environmental Protection Agency, 2006a). 

Mn concentrations in water samples ranged from less than 0.2 

to 660 μg/L; samples from 7 of the 10 bedrock wells and 5 of 

the 7 unconsolidated wells had exceedances of the secondary 

maximum contaminant level (MCL) (table 5, in back of 

report). Fe concentrations in water samples ranged from less 

than 4 to 1,800 μg/L; samples from 4 of the 10 bedrock wells 

and only 1 of the 7 unconsolidated wells had exceedances of 

the secondary MCL (table 5, in back of report). Concentrations 

of dissolved As in water sampled from domestic bedrock 

well U1645 was at the MCL of 10 μg/L (U.S. Environmental 

Protection Agency, 2006b). Sr concentrations were high 

in several bedrock wells, ranging up to 20 mg/L at U1630 

and U1631. High concentrations (greater than 1 mg/L) 

of dissolved Zn were observed in groundwater samples 

from drive-point wells that were previously installed by a 

consultant. Zn concentrations in samples from U1632 (spring) 

and U1633 (spring) were 2 and 5.3 mg/L, respectively, 

whereas Zn concentrations detected in all other samples were 

below 6 μg/L. These high Zn concentrations in the springs 

likely originated from the galvanized drive-point wells. 

Stable Isotopes

Stable isotopes were analyzed to help determine different chemical sources that affect flooding and the amount of 

mixing of the waters. The sources may have different isotopic 

signatures because of the type of source or chemical fractionation related to evaporative or chemical processes. Stable 

isotopes measured from constituents in water samples include 

δ18O, δ2

H, δ34S of SO4

2-, 87Sr/86Sr, and δ13C of DIC (table 5, in 

back of report).

The δ18O and δ2

H data for the study area generally plotted 

along an inferred local meteoric water line (LMWL) that was 

drawn through groundwater samples collected from sites in 

Wawarsing (not shown); the LMWL reflects the isotopic signature of local precipitation (Kendall and Coplen, 2000). Most 

groundwater and surface-water samples from Wawarsing plotted along a line with a slope of about 7.5. Water samples from 

the Rondout Reservoir plot along a slightly different meteoric 

water line (MWL), mostly due to seasonal evaporation that 

varies in intensity as summer progresses, which causes a linear 

pattern that deviates from the local line. The δ18O and δ2

H 

values in RWB Tunnel water vary seasonally as a result of 

evaporative concentration of the heavier isotopes, 18O and 2

H. 

Water samples collected during the warmer months are distinctly heavier in δ18O and δ2

H values than those in water from 

the RWB Tunnel and water from bedrock wells. Values of δ18O 

and δ2

H in rainfall also vary locally and at different altitudes 

(Coplen and Kendall, 2000); the higher altitude at the Rondout Reservoir (840 ft NAVD 88) compared to the Wawarsing 

study area (about 280 ft NAVD 88) could account for part of 

this deviation. 

The isotope ratios of δ34S of SO4

2− in groundwater 

samples ranged from -11.5 to 31.6 per mil (table 5, in back of 

report) and appear to reflect several processes and mixtures of 

sources. The δ34S of SO4

2− in water samples from most bedrock 

wells are much heavier and have higher SO4

2− concentrations, 

as compared to water samples from wells screened in unconsolidated deposits, springs, and surface water. 

Strontium (Sr) is a useful isotope for tracing water 

sources because the 87Sr/86Sr ratio does not fractionate during evaporation or precipitation and because Sr derived from 

any mineral will retain the same ratio in water (Bullen and 

Kendall, 1995). Sr in groundwater results from its interaction with aquifer material and should have a range of 87Sr/86Sr 

ratios similar to geologic material. Strontium concentrations 

are greater and 87Sr/86Sr ratios more depleted in groundwater samples from some bedrock wells (U1630, U1631, and 

U1647), as compared to other samples (table 5, in back of 

report), and likely reflect the isotopic signature from a different aquifer source and (or) the extent of water-rock interaction 

of this source.

The δ13C values for DIC in groundwater samples ranged 

from -23.5 to -8.17 per mil with a median of -14 per mil 

(table 5, in back of report). The slightly heavier δ13C of DIC 

in water samples from bedrock wells (-13.1 per mil at U1628; 

table 5, in back of report) could be related to the weathering of 
Water Sources and Chemistry 21

calcite in carbonate rocks, which contain heavier δ13C values. 

Many of the bedrock well samples are at or near saturation 

with respect to calcite (table 3, in back of report) and may 

indicate dissolution of calcite at some point along their flow 

paths. The δ13C of DIC in surface-water samples (median of 

-13.5 for all Lippman Lake and Rondout Reservoir samples) 

also could be enriched during summer months by algal 

blooms; the δ13C values for DIC in the Lippman Lake sample 

collected on July 2, 2009, was -8.17 per mil.

Groundwater Age

Samples were collected to estimate groundwater ages 

using the following tracers: 3H, SF6, and CFCs. Apparent 

groundwater age is defined as the time elapsed since recharge 

of a sampled parcel of water. Concentrations of 3H were 

measured in several wells to determine whether the water was 

older than 1953 (prior to nuclear atmospheric weapons testing) 

or younger. 

Dissolved gas concentrations were measured to estimate the temperature of groundwater at the time of recharge, 

because the solubility of atmospheric tracers varies as a function of temperature, and to calculate the amounts of excess 

air and N2 (table 4, in back of report). Recharge temperatures 

estimated from Ar and N2 dissolved gas concentrations varied 

among wells. The ratio of these dissolved gases (N2 and 

Ar) in water samples from several bedrock wells, including 

U1628, U1631, and U1630, indicate large amounts of excess 

air. Excess air consists of air trapped in pores that dissolves 

in groundwater, typically after a rapid rise in the water table, 

or some other source of atmospheric gases. Dissolved gas 

concentrations in all samples indicate that there was little or no 

excess N2, which can result from the reduction of NO3

-

, contributing to excess air. The ratio of dissolved gases in samples 

from several wells and a spring also appeared to be altered by 

degassing. The degassing was possibly caused by the generation of CH4

 and H2S gas bubbles resulting from organic-matter 

decomposition or other microbial processes that preferentially 

remove N2, which is less soluble than Ar. As a result of these 

gas problems in the samples (as described in “age tracer notes” 

in table 4, in back of report), the recharge temperatures, excess 

air volumes, and age-tracer concentrations of several bedrock 

wells could not be determined with confidence. These bedrock 

wells include U1628, U1631, U1630, and U1647.

Dating groundwater with 3H is qualitative at best, but 

can be useful in recognizing post-nuclear testing water, and 

can be used together with other tracers to estimate mixing of 

groundwater from various sources. Concentrations of 3H in 

samples from springs or wells screened in the unconsolidated 

deposits ranged from less than 0.03 picoCuries per liter 

(pCi/L) in well U1637, which had an upward-flow gradient, 

to 60 pCi/L in well U1666, a basement spring sample 

collected on June 23, 2009 (table 4, in back of report). These 

ranges in values reflect, in part, the high seasonal and annual 

variations of 3H observed in precipitation (Clark and Fritz, 

1997). Concentrations of 3H in samples from bedrock wells 

ranged from <0.03 to 60 pCi/L. Samples from wells that had 

low 3H concentrations (<10 pCi/L) could be current or have 

substantial components of old water that were recharged 

before 1953. The low 3H concentration (<0.03 pCi/L) in the 

groundwater sample from unconsolidated aquifer well U1637 

indicates that the water likely was recharged before 1953. 

The sample from U1641—the adjacent, deeper well screened 

in unconsolidated deposits—also had a low 3H concentration 

(1.1 pCi/L) compared to other unconsolidated aquifer wells 

and is consistent with the upward-head gradient at that 

location, indicating that older groundwater is flowing upward 

from bedrock. The upper range value of 60 pCi/L in a sample 

from the well U1666 basement spring indicates that either the 

water was recharged during the 3H peak in the early 1960s or 

that the water was affected by 3H contamination, possibly from 

a nearby landfill. The early 1960s recharge date is unlikely, 

given the young apparent recharge years indicated by the age 

tracers SF6, CFC-11, CFC-12, and CFC-113, as discussed later 

in this section.

Results of the CFC and SF6 age tracers for samples from 

several of the wells screened in unconsolidated deposits and 

springs showed conflicting apparent ages and recharge years. 

The apparent SF6 ages generally were younger than those of 

CFC ages, apparently caused by the degradation of CFCs, 

which results in erroneously young apparent ages. The CFC11 and CFC-113 tracers are prone to degradation under reducing conditions. Other limitations of CFCs include problems 

with dating extremely young waters (Hunt and others, 2005), 

issues with mixing of waters of varying age (Goode, 1996; 

Bethke and Johnson, 2002; Weissman and others, 2002), and 

the leveling off or declining of atmospheric concentrations 

over time (Plummer and Busenberg, 1999). The SF6 ages 

of samples from wells screened in unconsolidated deposits 

and springs seemed more reasonable; recharge years of most 

springs or wells ranged from 2003.0 to 2009.5 and indicate 

short flow paths from the point of groundwater recharge. The 

exception is the sample from well U1641, which had an apparent SF6

 recharge year of 1975–76. Adequate flow could not be 

obtained from nearby well U1637 to produce dissolved-gas 

or age-tracer samples, but the upward-flow gradient at this 

location is consistent with the older recharge year and a longer 

flow path.

CFC age-tracer samples also were collected from 

Lippman Lake and Rondout Reservoir because they could 

be important sources of groundwater in the study area. The 

presence of CFC-11, CFC-12, and CFC-113 in samples from 

both surface-water bodies showed degradation, which is 

common in northern temperate lakes owing to organic-rich 

sediments and anoxic conditions (Walker and others, 2007). 

Recharge temperatures were estimated for Lippman Lake 

effluent and Rondout Reservoir samples because dissolved gas 

samples were not collected at these sites. The water-sample 

temperature at the time of collection was used for recharge 

temperatures at Rondout Reservoir. At Lippman Lake, the 

mean annual air temperature (10°C) was used for the sample 
22 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

collected on June 23, 2009; for the sample collected on 

December 22, 2009, the mean air temperature for the previous 

2 months, November and December (7°C), was used for the 

estimated recharge temperature because it was judged to be 

more representative of water in this shallow water body during 

this time of year (table 4, in back of report).

As discussed earlier in this section, most of the samples 

from bedrock wells had interference problems with dissolved 

gases, either because of excess air from trapped bubbles in 

recharge water or degassing from high concentrations of H2S 

and CH4. Water samples from three wells, U1629, U1625, 

and U1645, did not appear to have these problems, at least 

enough to prevent apparent-age estimates. A sample from 

U1629, which is located near the RWB Tunnel, had an apparent “piston recharge” year of early 1950s, consistent with 

other chemistry that showed little or no similarity to the tunnel water chemistry. “Piston recharge” assumes that a tracer 

becomes incorporated in a parcel of water that moves from 

the recharge area with the mean velocity of groundwater. The 

CFC apparent-recharge year based on CFCs was similar to 

that based on SF6. Well U1625 was sampled on two occasions. 

The June 24, 2009 sample, collected during a period of nearby 

basement flooding, indicated consistency between the SF6

recharge year of 2003 and the CFC-12 apparent-recharge year 

of 2002.8. CFC-11 and CFC-113 are more prone to degradation under reducing conditions and likely are not as reliable 

in this sample. The degradation of these CFCs indicates that 

some component of reducing water contributes to the well. 

The later sample was collected on December 14, 2009, during 

a period of lower head pressure in the tunnel (Stumm and 

others, 2012), and the apparent SF6 recharge year of 2000.5 

indicates a greater component of older water, apparently 

caused by a lower contribution of water from the RWB Tunnel 

and a greater contribution from ambient groundwater. The 

reducing properties of ambient water from bedrock also might 

have resulted in degradation of CFCs in the sample collected 

on December 14, 2009, at well U1625. A sample from U1645 

had an SF6 apparent recharge year of 1970, but one or more of 

the CFCs was degraded and yielded older ages.

Summary and Conclusions

The U.S. Geological Survey and the New York City 

Department of Environmental Protection conducted a cooperative study to evaluate the water chemistry and potential effects 

of flooding in Wawarsing, N.Y. These data, together with 

hydrogeologic data, can be used to improve the understanding 

of source waters and groundwater-flow patterns and pathways 

and to help assess mixing of the different source waters in 

water samples. 

Major-ion concentrations in water samples collected during the study show differences depending on the sample type, 

depth, and location. Water samples from most wells screened 

in unconsolidated deposits and springs had a greater percentage of calcium as compared to other cations than samples from 

bedrock wells. The exception was well U1625, which had 

high ratios of bicarbonate and calcium relative to other ions 

similar to samples from the unconsolidated aquifer wells and 

the surface-water samples. Samples from bedrock wells generally had relatively higher concentrations of sulfate (SO4

2-) as 

compared to other anions. Water samples from most wells 

screened in unconsolidated deposits and springs were greater 

in bicarbonate and carbonate than in SO4

2- and chloride, as 

compared to samples from bedrock wells. Differences in 

calcite and gypsum saturation indexes in water samples were 

evident among (1) most bedrock wells and wells screened in 

unconsolidated aquifer wells and (2) water samples collected 

from two bedrock wells during high head pressure and water 

samples collected during low head pressure of the Rondout–

West Branch (RWB) Tunnel. Concentrations of trace constituents, including strontium (Sr), barium (Ba), arsenic (As), 

boron (B), lithium (Li), nickel (Ni), and lead (Pb), generally 

were higher in samples from bedrock wells than in samples 

from wells screened in unconsolidated deposits and in water 

from RWB Tunnel or in the lake at Lippman Park.

Nitrate (NO3

-

) plus nitrite (NO2

-

) concentrations ranged 

from less than minimum reporting levels (MRLs) in water 

samples with reducing redox characteristics to 0.88 milligram 

per liter (mg/L) as nitrogen (N) for a domestic well in a residential area with onsite septic-tank drainfields (table 3, in back 

of report). Concentrations of NO2

-

 were less than the MRL of 

0.008 mg/L in all but two samples; therefore, NO3

-

 plus NO2

-

is referred to herein as “NO3

-

.” The median concentration of 

NO3

-

 for wells in the study area was less than 0.5 mg/L as N, 

and samples at more than one-half of the sites were below the 

reporting level of 0.04 mg/L as N. Urban septic-system leachate and lawn fertilizer are the major sources of NO3

-

 in the 

study area and can affect shallow groundwater quality.

Dissolved gas concentrations were measured to estimate the temperature of groundwater at the time of recharge, 

because the solubility of atmospheric tracers varies as a function of temperature, and to calculate the amount of excess air 

and excess nitrogen (N2). Recharge temperatures estimated 

from argon (Ar) and N2 dissolved gas concentrations varied 

among wells. Most of the samples from bedrock wells had 

interference problems with dissolved gases, either because of 

excess air from trapped bubbles in recharge water or degassing from high concentrations of hydrogen sulfide (H2

S) and 

methane (CH4). The ratio of N2 and Ar in water samples from 

several bedrock wells, including U1628, U1631, and U1630, 

indicated large amounts of excess air and (or) degassing.

Age-tracer data provided useful information on pathways 

of the groundwater-flow system but were limited by inherent problems with dissolved gas data. Tritium concentrations 

in samples from springs or wells screened in unconsolidated 

deposits ranged from less than 0.03 picoCurie per liter (pCi/L) 

in an unconsolidated aquifer well with an upward-flow gradient to 60 pCi/L in a basement spring sample. Results of the 

chlorofluorocarbon (CFC) and sulfur hexafluoride (SF6) age 

tracers for some of the wells screened in unconsolidated 

deposits and springs showed conflicting apparent ages and 
References Cited 23

recharge years. The apparent SF6 ages generally were younger 

than those of CFC ages, apparently caused by the degradation 

of CFCs that resulted in erroneously young apparent ages. 

The SF6 ages of the wells screened in unconsolidated deposits 

and springs seemed more reasonable; recharge years of most 

springs or shallow wells ranged from 2003 to 2010 (current) 

and indicate short flow paths from the point of groundwater 

recharge. The exception is an apparent age of early to mid1970s for a sample from well U1641 that is screened in poorly 

permeable sediments and had an upward-flow gradient.

Water samples from three bedrock wells, U1629, U1625, 

and U1645, did not appear to have a problem with dissolved 

gases that prevented apparent-age estimates. A sample from 

U1629, which is located near the RWB Tunnel, had an 

apparent piston recharge date of early 1950s, consistent with 

other chemistry that showed little or no similarity to the water 

chemistry in the tunnel. The apparent recharge year based on 

CFCs was similar to that of SF6. Well U1625 was sampled on 

two occasions. The sample collected June 24, 2009, during 

a period of nearby basement flooding, indicated consistency 

between the SF6 recharge year of 2003 and the CFC-12 

apparent recharge year of 2002.8. CFC-11 and CFC-113 are 

more prone to degradation under reducing conditions and 

likely are not as reliable in this sample. The degradation of 

these CFCs indicates that some component of reducing water 

contributes to the well. The later sample was collected on 

December 14, 2009, during a period of lower head pressure 

in the tunnel (Stumm and others, 2012), and the apparent 

SF6 recharge year of 2000.5 indicates a greater component of 

older water, apparently caused by less contribution of water 

from the RWB Tunnel and greater contribution from ambient 

groundwater. A sample from U1645 had an SF6 apparent 

recharge year of 1970.

Stable isotopes were analyzed to help determine different chemical sources that affect flooding and the amount 

of mixing of the waters. Differences in stable-isotope ratios 

among δ18O, 2H, δ34S of SO4

2-, 87Sr/86Sr, and δ13C of dissolved 

inorganic carbon (DIC) indicate potential for distinguishing 

water in Delaware–West Branch Tunnel from native groundwater. The δ18O and δ2

H values in water from the RWB Tunnel 

vary seasonally as a result of evaporative concentration of the 

heavier isotopes, 18O and 2H. Water samples collected during 

the warmer months showed distinct differences between water 

from the RWB Tunnel and water from bedrock wells. The δ34S 

of SO4

2- in water samples from most bedrock wells are much 

heavier and have higher SO4

2- concentrations, as compared to 

water samples from wells screened in unconsolidated deposits, springs, and surface water. Strontium concentrations are 

greater and 87Sr/86Sr ratios are more depleted in groundwater 

samples from most bedrock wells, as compared to samples 

from surface-water sources, springs, and wells screened in 

unconsolidated deposits in the study area. The heavier δ13C 

of DIC in water samples from bedrock wells could be related 

to the weathering of calcite in carbonate rocks, which contain 

heavier δ13C values. Many of the bedrock well samples were 

at or near saturation with respect to calcite and may indicate 

dissolution of calcite at some point along their flow paths.

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THIS PAGE INTENTIONALLY LEFT BLANK
Tables 3–5
28 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Table 3. General chemical characteristics, concentrations of major elements and nutrients, saturation indexes, and percent charge balance error in surface- 

Branch Tunnel in Lackawack, Ulster County, New York, 2009–11.

[mS/cm, microsiemens per centimeter at 25 degrees Celsius; SI, saturation index; concentrations in milligrams per literunless indicated otherwise; Ca, calcium; Mg, magne- 

N, nitrogen; PO4

3−, orthophosphate; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level]

Well identifier Date

Sample 

time

Temperature, 

water 

(degrees 

Celsius)

pH

Specific 

conductance 

(μS/cm)

Depth 

of well 

(feet below land 

surface)

Dissolved 

solids

Hardness, 

as 

CaCO3

Ca Mg K Na Alkalinity HCO3

- CO32- Cl- BrCl.Br 

mass 

ratio

U1626 12/15/2009 1500 8.8 6.3 94 10 67 43 14 1.9 0.43 2.3 41 50 <0.1 1.2 0.01 120 

U1627 6/23/2009 1200 15.8 6.8 499 15 338 160 56 6.0 1.35 52 -- 160 <0.1 96 0.04 2,400 

U1627 4/1/2010 0900 6.8 6.9 551 15 281 130 45 4.5 0.94 53 120 140 <0.1 86 0.03 2,867 

U1637 8/31/2010 1400 15.6 7.8 226 26.5 135 104 32 5.6 1.25 4.2 90 110 <0.1 1.6 0.011 145 

U1641 4/20/2010 1300 11.6 8.0 224 117 137 110 34 6.1 0.94 3.8 60 73 <0.1 1.9 0.01 190 

U1641 4/20/2010 1301 -- 8.0 224 117 140 110 33 6.0 0.86 3.8 60 73 <0.1 1.9 0.01 190 

U1663 8/31/2010 1400 14.5 8.2 286 47 167 79 23 5.1 1.9 32 130 160 <0.1 9.0 0.065 138 

U1673 11/30/2011 1200 11.6 7.7 345 180 188 160 50 9.3 0.68 8.4 120 150 <0.1 21 0.02 1,050 

U1670 11/30/2011 1000 12.2 8.0 350 180 197 160 49 8.3 0.77 12 120 140 <0.1 30 0.02 1,500 

U1632 9/14/2009 1730 11.3 6.2 105 NA 54 38 12 2.1 0.43 1.7 37 46 <0.1 1.1 0.01 110 

U1633 9/15/2009 1200 16.1 6.3 85 NA 43 22 6.7 1.4 0.96 1.2 22 27 <0.1 1.1 0.01 110 

U1667 9/15/2009 1400 13.4 6.9 66 NA 41 23 6.8 1.5 0.69 1.5 16 21 <0.1 1.1 0.01 110 

U1668 7/1/2009 1300 14.8 6.9 78 NA 53 29 8.3 2.1 0.47 2.0 22 28 <0.1 1.4 0.01 140 

U1666 6/23/2009 1400 13.6 6.7 284 NA 195 160 55 5.0 1.6 7.3 150 180 <0.1 7.3 0.01 730 

U1666 3/31/2010 1600 7.5 6.8 332 NA 189 150 54 4.7 1.3 4.5 150 180 <0.1 6.2 0.01 620 

U1665 3/31/2010 1200 6.4 6.0 60 NA 46 18 5.8 0.92 1.2 2.0 13 16 <0.1 4.1 0.01 410 

Lippman Lake 

effluent

6/24/2009 1330 -- -- -- NA -- -- -- -- -- -- -- -- -- -- -- -- 

Lippman Lake 

effluent

7/2/2009 1300 22.7 7.6 52 NA 53 41 13 2.4 0.50 2.3 36 43 <0.1 1.9 0.01 190 

Lippman Lake 

effluent

9/1/2009 1230 -- -- -- NA -- -- -- -- -- -- -- -- -- -- -- -- 

Lippman Lake 

effluent

9/16/2009 1300 21.2 7.3 217 NA 157 120 38 6.4 0.90 5.7 110 140 1 7.7 0.04 193 

Lippman Lake 

effluent

10/13/2009 1515 13.8 7.4 231 NA -- -- -- -- -- -- -- -- <0.1 -- -- -- 

Lippman Lake 

effluent

12/15/2009 1000 0.8 5.5 86 NA 60 32 9.3 2.2 0.37 2.7 29 35 <0.1 2.2 0.01 220 

Lippman Lake 

effluent

4/1/2010 1200 11.2 7.2 97 NA 65 39 12 2.2 0.42 2.4 36 44 <0.1 2.7 0.01 270 

01366400 6/23/2009 0930 10.3 6.4 60 NA 36 14 4 0.95 0.43 4.2 17 21 <0.1 6.9 0.01 690 

01366400 9/1/2009 1030 15.4 6.2 45 NA 26 13 3.8 0.82 0.44 3.5 7.0 9.0 <0.1 5.7 0.01 570 

01366400 10/13/2009 1420 15.9 7.4 50 NA -- -- -- -- -- -- -- -- -- -- -- -- 

01366400 10/13/2009 1425 -- -- -- NA -- -- -- -- -- -- -- -- -- -- -- -- 

01366400 12/22/2009 1110 6.7 7.2 53 NA 38 15 4.2 0.98 0.51 3.7 12 14 <0.1 5.8 0.01 580 

01366400 4/1/2010 1000 5.4 7.1 51 NA 37 12 3.6 0.82 0.49 3.4 10 12 <0.1 6.0 0.01 600 

U1625 6/24/2009 1100 11 7.5 134 275 84 63 20 2.8 0.65 5.5 57 70 0.1 7.5 0.02 375 

U1625 12/14/2009 1000 10.8 7.2 413 275 306 250 75 14 1.1 10 210 260 <0.1 9.3 0.04 233 

U1625 4/7/2011 1900 -- 7.6 109 275 63 -- 12 1.7 0.59 5.2 30 37 <0.1 7.3 <.01 1,450 

U1629 6/24/2009 0800 11.8 7.8 780 118 480 200 61 11 1.0 87 160 190 0.4 150 1.4 107 

U1629 4/7/2011 1100 -- 7.0 370 118 260 -- 64 10 1.0 18 160 190 -- 40 0.32 125 

U1629 4/7/2011 0900 -- 7.3 370 118 240 -- 64 10 0.96 9.1 160 200 -- 19 0.11 173 

U1628 7/2/2009 1000 12.8 8.1 409 200 320 190 44 20 1.0 23 66 80 0.4 20 0.15 133 

U1630 9/15/2009 1700 12.8 7.9 797 NA 580 290 65 31 1.5 48 8 9.8 <0.1 45 0.45 100 

U1631 9/16/2009 1000 12.8 7.6 1,170 NA 930 540 150 37 2.3 46 96 120 <0.1 58 0.53 109 

U1631 9/16/2009 1001 12.8 7.6 1,170 NA 920 540 150 37 2.3 46 96 120 <0.1 57 0.54 106 

U1631 12/14/2009 1630 11.5 8.0 905 NA 850 500 130 36 2.2 42 95 120 <0.1 54 0.52 104 

U1647 4/21/2010 1300 15.8 7.9 1,640 NA 1,100 460 110 39 5.4 170 100 130 <0.1 250 2.2 114 

U7017 9/20/2011 1200 12.1 6.9 236 NA 140 36 10 2.4 1.7 37 99 120 <0.1 18 0.13 138 

U3772 9/20/2011 1200 11.6 6.8 232 NA 140 49 15 2.3 2.3 30 120 140 <0.1 1.7 <0.01 680 

U1645 9/21/2011 1200 12.9 7.2 443 NA 20 200 53 16 1.1 11 170 210 <0.1 7.6 0.036 210 

U1644 9/21/2011 1200 14.3 7.8 1,060 NA 550 200 46 20 1.2 130 160 190 <0.1 210 1.7 120 
Table 3 29

water and groundwater samples from a lake, springs, and wells in the Wawarsing study area, and for the Rondout Reservoir at the influent to the Rondout–West 

 sium; K, potassium; Na, sodium; HCO -, bicarbonate; Cl−, chloride; Br−, bromide; F-, fluoride; SiO , silica; SO 2−, sulfate; NH +, ammonia; NO −, nitrate; NO −, nitrite; 3 2 4 4 3 2

F- SiO2

2- SO4 NH +

4

NO -

3

plus 

NO - 

2

as N

NO -

2

as N

Ortho- 3- PO 4

as P

Total N Water type log 

[Ca+2]

log 

[Mg+2]

SI 

(Calcite)

SI 

(Dolomite)

SI 

(Gypsum)

SI 

(Fluorite)

SI 

(Quartz)

Charge 

balance 

error 

(percent)

<.08

E.05

E.06

0.135

0.1

0.1

0.44

<.04

0.06

<.08

<.08

<.08

E.04

<.08

E.05

<.08

--

E.04

--

0.12

--

<.08

E.04

<.08

<.08

--

--

<.08

<.08

<.08

E.05

<0.04

0.11

0.1

0.1

0.19

0.32

0.16

0.19

0.16

0.38

0.53

0.31

0.09

0.34

9.4

5.2

4.4

2.5

12

12

1.6

8.6

8.6

7.1

7.7

8.3

8.2

6.0

4.7

4.6

--

4.7

--

5.4

--

7.5

4.8

2.0

1.7

--

--

2.0

2.1

3.0

7.8

2.7

12

11

11

10

9.1

13

13

13

9.9

7.1

6.7

12

9.4

8.7

14

17

21

27

27

3.4

25

20

14.2

11.0

12.6

11.4

13.1

13.9

6.41

--

5.22

--

5.87

--

9.64

7.10

4.86

4.42

--

--

4.55

4.48

11.1

44.0

9.2

23

25

26

140

270

470

470

430

330

0.13

0.31

49

26

<.020

<.020

<.020

0.039

0.033

0.032

0.092

0.013

0.018

<.020

<.020

<.020

E.014

<.020

<.020

0.027

--

<.020

--

<.020

--

<.020

<.020

0.029

0.031

--

--

<.020

<.020

<.020

<.020

<0.01

0.18

--

--

0.16

0.12

0.16

0.16

0.15

0.58

0.18

0.4

0.1

0.32

0.14

0.51

0.71

<0.04

<0.04

<0.04

<0.04

<0.04

<0.04

E.03

0.04

<0.04

E.02

0.16

0.48

0.35

--

<0.04

--

<0.04

--

E.02

<0.04

0.20

0.12

--

--

0.16

0.18

0.26

0.88

0.24

<0.04

--

--

<0.04

<0.04

<0.04

E.03

<0.04

<0.04

<0.02

<0.02

<0.02

<0.02

<.002

<.002

<.002

<0.002

<.002

<.002

<0.002

<.001

<.001

<.002

<.002

<.002

<.002

<.002

<.002

E.001

--

<.002

--

<.002

--

E.001

<.002

<.002

E.001

--

--

<.002

<.002

<.002

0.020

<0.001

<.002

--

--

<.002

<.002

<.002

<.002

<.002

<.002

<0.001

<.001

<.001

<.001

E.005

0.031

0.024

0.016

0.013

0.012

0.02

0.006

0.006

0.020

0.013

0.024

0.026

0.042

0.041

0.026

--

E.007

--

E.004

--

E.004

E.004

<.008

<.008

--

--

<.008

<.008

E.006

E.005

0.0058

0.048

--

--

0.013

E.006

0.009

0.008

E.006

0.013

0.0079

0.015

0.005

0.099

0.21

0.60

0.80

<.10

<.10

<.10

<.10

<.05

<.05

<.10

0.12

E.08

0.19

0.33

0.57

0.45

--

0.28

--

0.25

--

0.17

0.1

0.31

0.24

--

--

0.20

0.25

0.34

0.94

--

0.20

--

--

0.18

0.12

0.14

0.15

0.15

0.55

0.21

0.44

0.13

0.36

Ca-HCO3

Ca-Na-Cl-HCO3

Na-Ca-Cl-HCO3

Ca-HCO3

Ca-Mg-HCO -SO 3 4

--

Na-Ca-HCO3

Ca-HCO -Cl 3

Ca-Mg-HCO3

Ca-HCO3-SO4

Ca-Zn-HCO3-SO4

Ca-Mg-HCO -SO 3 4

Ca-Mg-HCO3-SO4

Ca-HCO3

Ca-HCO3

Ca-HCO -SO -Cl 3 4

--

Ca-Mg-HCO3

--

Ca-HCO3

--

Ca-Mg-HCO -SO 3 4

Ca-HCO3

Ca-Na-HCO3-Cl

Ca-Na-Cl-HCO -SO 3 4

--

--

Ca-Na-HCO -Cl 3

Ca-Na-HCO3-Cl-SO4

Ca-HCO3

Ca-Mg-HCO3

--

Na-Ca-Cl-HCO3

Ca-HCO3-Cl

Ca-HCO3

Ca-Mg-Na-SO4-HCO3

Ca-Mg-Na-SO4

Ca-Mg-SO4

Ca-Mg-SO4

Ca-Mg-SO4

Na-Ca-Cl-SO4

Na-Ca-HCO -Cl 3

Na-Ca-HCO3

Ca-Mg-HCO3-SO4

Na-Ca-Cl-HCO3

-3.5275

-3.0207

-3.1021

-3.2221

-3.2025

-2.7452

-3.3642

-3.0528

-3.0567

-3.6176

-3.8477

-3.8373

-3.7575

-3.0073

-3.0086

-3.8997

--

-3.5763

--

-3.1497

--

-3.7075

-3.5962

-4.0529

-4.0756

--

--

-4.0297

-4.098

-3.3886

-2.9054

-3.5851

-3.0039

-2.96

-2.96

-3.1628

-3.0424

-2.7527

--

-2.7913

-2.8605

-3.7061

-3.5308

-3.0497

-3.139

-4.1936

-3.7667

-3.8803

-3.7646

-3.7301

-3.1179

-3.8067

-3.5639

-3.6092

-4.146

-4.3262

-4.2704

-4.1308

-3.8304

-3.8475

-4.4761

--

-4.0878

--

-3.7022

--

-4.1121

-4.119

-4.4652

-4.5221

--

--

-4.4461

-4.5207

-4.0324

-3.4089

-4.2338

-3.5328

-3.5268

-3.5477

-3.281

-3.149

-3.1256

--

-3.1246

-3.0973

-4.1093

-4.1321

-3.405

-3.2759

-2.4306

-0.8423

-1.0107

-0.1996

-1.0795

-1.0795

0.2152

-0.2499

-0.0889

-2.6175

-2.9039

-2.4642

-2.2168

-0.8851

-0.8976

-3.6296

--

-1.0385

--

-0.4377

--

-3.6966

-1.6173

-3.2022

-3.7123

--

--

-2.5853

-2.8753

-0.9162

-0.1906

-1.285

0.1928

-55.03

-0.4101

-0.0319

-1.0502

0.0235

--

0.3555

0.2891

-1.5821

-0.0561

-0.3878

0.0866

-5.6473

-2.4281

-2.9587

-0.9424

-2.6212

-2.6212

-0.0306

-0.0689

-0.7896

-5.837

-6.2791

-5.3985

-4.8205

-2.6269

-2.7793

-8.0028

--

-2.4867

--

-1.346

--

-8.0853

-3.833

-6.9085

-7.8749

--

--

-5.748

-6.3607

-2.5553

-0.9673

-3.2977

-0.2079

-1.7322

-1.3424

-0.2293

-2.2541

-0.3731

--

0.3077

0.344

-3.6268

-4.554

-1.1118

0.0144

-3.073

-2.4732

-2.4423

-2.4445

-2.331

-0.8018

-3.3739

-2.2404

-2.3377

-2.9528

-3.2865

-3.2048

-3.1787

-2.4753

-2.4337

-3.5388

--

-3.3565

--

-2.9531

--

-3.1722

-3.2284

-3.8186

-3.8838

--

--

-3.8142

-3.8822

-2.8541

-1.8878

-3.1062

-2.2709

-2.1732

-2.1662

-1.6361

-1.2671

-0.8111

--

-0.8747

-1.0832

-5.1023

-4.554

-1.9684

-2.3723

-3.5058

-3.5589

-3.3503

-2.8685

-3.169

-2.2993

-1.9723

-4.9295

-3.3666

-3.6333

-3.9474

-3.8786

-4.4212

-3.0961

-3.4084

-3.9239

--

-4.3451

--

-2.9777

--

-3.6651

-4.2108

-4.0851

-4.3282

--

--

-3.9614

-4.0124

-3.409

-3.3838

-4.4468

-2.8165

-2.6838

-2.9534

-2.5125

-1.967

-2.1589

--

-2.3221

-1.7175

-2.1041

-2.3871

-3.0443

-2.0249

0.4295

0.0565

0.1292

-0.2635

0.3483

0.5134

-0.43

0.3296

0.3414

0.2627

0.2222

0.2993

0.2729

0.1585

0.1498

0.1557

--

-0.0934

--

-0.0091

--

0.4671

0.0928

-0.2784

-0.4322

--

--

-0.202

-0.1634

-0.1131

0.3132

-0.152

0.4901

0.447

0.3182

0.4056

0.345

0.5135

--

0.535

0.3346

0.2516

0.2283

0.4668

0.3369

-3.2

-0.21

-1.7

0.12

14

13

0.12

-1.1

-1.5

-13

-15

-6.5

-3.8

-0.2

-1.6

-5.4

--

4.0

--

1.3

--

-4.4

-2.4

-16

1.2

--

--

-4.5

-8.0

-3.1

-0.33

0.69

-1.0

-1.0

-0.87

1.2

5.2

-1.5

-1.3

-1.6

2.9

3.1

0.86

1.7

0.68
30 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Table 4. Concentrations of dissolved gases and age tracers, redox properties, and apparent age of surface-water and groundwater samples from a lake, 

New York, 2009–11.—Continued

[--, not measured; <, less than; E, estimated value below minimum reporting level; NP, age estimate not possible; C, current age; apparent recharge years and ages for 

redox, oxidation–reduction; O2, oxygen reducing, NO3

-

, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO4

2-, sulfate reducing; FeSO4

, iron- to sulfate- 

unless otherwise noted; mol/kg, moles per kilogram; pptv, parts per trillion by volume; pmol/kg, picomoles per kilogram; cm3STP/L, cubic centimeters at standard 

Well 

identifier Date

Sample 

time

Dissolved 

oxygen 

(DO)

Sulfide 

(H2S)1

Methane 

(CH4)

1

Nitrogen 

(N2)

1

Argon 

(Ar)1

Carbon 

dioxide 

(CO2)

1

Redox class 

category

Predominant 

redox 

process

Recharge 

temp 

(degrees 

Celsius)1

Excess 

air

(cm3

STP/L)1

Tritium, 

picocuries 

per 

liter2

SF6 in 

water 

(femtomol/kg)3

Calculated SF6

partial 

pressure 

(pptv)3

U1626 12/15/2009 1500 4.4 0.002 <0.001 21 0.74 42 Mixed (oxic/

sulfidic)

O2-SO4

2- 8.6 2.3 26.1 2.86 5.55 

U1627 6/23/2009 1200 5.6 <0.002 -- -- -- -- Oxic O2 -- -- -- -- -- 

U1627 4/1/2010 0900 8.6 <0.002 <0.001 23 0.86 30 Oxic O2 6 3.9 27.5 3.59 5.65 

U1637 8/31/2010 1400 3 -- -- -- -- -- Mixed (oxicmethanogenic)O2-Fe(III) -- -- <0.03 -- -- 

U1641 4/20/2010 1300 0.8 0.014 0.002 22 0.75 1.6 Mixed (oxicmethanogenic)O2-CH4 10.1 4.1 1.1 0.273 0.479 

U1641 4/20/2010 1301 -- -- -- -- -- -- -- -- 10.1 4.1 1.1 0.279 0.489 

U1663 8/31/2010 1400 2.9 -- -- -- -- -- Oxic O2 -- -- 17.7 -- -- 

U1673 11/30/2011 1200 0.5 <0.002 0.0087 22.0 0.76 3.6 Mixed (oxic/

methanogenic)

O2-CH4 7.8 3.8 0.20 1.03 1.77 

U1670 11/30/2011 1000 0.6 <0.002 0.012 23.4 0.77 2.9 Mixed (oxic/

methanogenic)

O2-CH4 9.6 6.0 0.30 -- -- 

U1632 9/14/2009 1730 5.9 -- <0.001 20 0.72 30 Oxic O2 10.0 0.7 14.8 2.50 6.25 

U1633 9/15/2009 1200 8.5 -- -- -- -- -- Oxic O2 8.7 1.5 -- -- -- 

U1667 9/15/2009 1400 9.9 -- -- -- -- -- Mixed (oxic/

anoxic)

O2-Mn(IV) -- -- -- -- -- 

U1668 7/1/2009 1300 9.5 -- -- -- -- -- Mixed (oxic/

anoxic)

O2-Mn(IV) -- -- -- -- -- 

U1666 6/23/2009 1400 5.0 -- <0.001 17 0.64 74 Oxic O2 12.3 0 60 2.39 6.77 

U1666 3/31/2010 1600 7.7 -- <0.001 23 0.84 44 Oxic O2 6 2.0 26.9 3.42 5.75 

U1665 3/31/2010 1200 6.4 E0.001 <0.001 24 0.88 28 Oxic O2 1.2 2.2 24.8 3.72 5.55 

Lippman Lake 

effluent

6/24/2009 1330 -- -- -- -- -- -- O2 ≥ 0.5 mg/L -- -- -- -- -- -- 

Lippman Lake 

effluent

7/2/2009 1300 8.9 -- -- -- -- -- O2 ≥ 0.5 mg/L O2-Mn(IV) 10* 0 -- -- -- 

Lippman Lake 

effluent

9/1/2009 1230 -- -- -- -- -- -- O2 ≥ 0.5 mg/L -- -- -- -- -- -- 

Lippman Lake 

effluent

9/16/2009 1300 11 -- -- -- -- -- Oxic O2 -- -- -- -- -- 

Lippman Lake 

effluent

10/13/2009 1515 -- -- -- -- -- -- O2 ≥ 0.5 mg/L -- -- -- -- -- -- 

Lippman Lake 

effluent

12/15/2009 1000 7.3 -- -- -- -- -- Mixed (oxic/

anoxic)

O2-Mn(IV) 7# 0 -- -- -- 

Lippman Lake 

effluent

4/1/2010 1200 9.9 -- -- -- -- -- Mixed (oxic/

anoxic)

O2-Mn(IV) -- -- -- -- -- 

01366400 6/23/2009 0930 9.6 -- -- -- -- -- Oxic O2 10& 0 -- -- -- 

01366400 9/1/2009 1030 -- -- -- -- -- -- Oxic O2 -- -- -- -- -- 

01366400 10/13/2009 1420 -- -- -- -- -- -- O2 ≥ 0.5 mg/L -- -- -- -- -- -- 

01366400 10/13/2009 1425 -- -- -- -- -- -- O2 ≥ 0.5 mg/L -- -- -- -- -- -- 

01366400 12/22/2009 1110 -- -- -- -- -- -- Oxic O2 7& 0 -- -- -- 
Table 4 31

springs, and wells in the Wawarsing study area, and for the Rondout Reservoir at the influent to the Rondout–West Branch Tunnel in Lackawack, Ulster County, 

 SF and CFCs have been corrected for excess air; SF , Sulfur hexafluoride; CFC, chlorofluorocarbon; bold text indicates most reasonable apparent age or recharge year; 6 6

 reducing; CH , methanogenic; mixed (Y/Z) indicates waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, 4

 temperature and pressure per liter; pCi, picocuries per liter]

SF Ap- 6

parent 

recharge 

year, piston flow3

SF 6

Apparent age, 

piston 

flow3

CFC-11 

corrected 

concentration 

(pmol/kg)3

CFC-12 

corrected 

concentration 

(pmol/kg)3

CFC-113 

corrected 

concentration 

(pmol/kg)3

CFC-11 

Apparent 

age piston 

flow 

(years)3

CFC-12 

Apparent 

age 

piston 

flow 

(years)3

CFC-113 

Apparent 

age 

piston 

flow 

(years)3

CFC-11 

Apparent 

recharge 

year, 

piston 

flow3

CFC-12 

Apparent 

recharge 

year, 

piston 

flow3

CFC-113 

Apparent 

recharge 

year, 

piston 

flow3

Dissolved gas notes Age tracer notes

2004.0

--

2004.5

--

1975.5

1976.0

--

1986.8

--

2007.2

--

--

--

2009.5

2005.0

2004.3

--

--

--

--

--

--

--

--

--

--

--

--

6.0

--

5.8

--

34.8

34.3

--

25.2

--

2.5

--

--

--

0

5.2

6.0

--

--

--

--

--

--

--

--

--

--

--

--

0.742

--

4.08

--

0.371

0.373

--

44.8

--

5.06

--

--

--

5.59

5.96

4.41

--

2.36

--

--

--

5.07

--

6.07

--

--

--

3.54

1.46

--

3.63

--

0.992

0.955

--

4,459

--

2.85

--

--

--

2.60

3.55

3.79

--

1.97

--

--

--

4.59

--

3.20

--

--

--

3.15

0.141

--

0.591

--

0.058

0.058

--

0.0298

--

0.438

--

--

--

0.485

0.663

0.619

--

0.231

--

--

--

0.651

--

0.532

--

--

--

0.50

44.0

--

32.0

--

47.3

47.3

--

NP

--

2.2

--

--

--

C

24.0

35

--

34.5

--

--

--

25.5

--

C

--

--

--

32.5

34.0

--

14.0

--

37.8

37.8

--

NP

--

C

--

--

--

3.5

0.2

NP

--

26.5

--

--

--

C

--

C

--

--

--

18.5

31.2

--

21.3

--

37.3

37.3

--

44.6

--

21.2

--

--

--

14.0

5.2

23

--

26.0

--

--

--

11.8

--

14.7

--

--

--

21.5

1966

--

1978.3

--

1963

1963

--

NP

--

2007.5

--

--

--

C

1986

1975.5

--

1975.0

--

--

--

1984.5

--

C

--

--

--

1977.5

1976

--

1996.3

--

1972.5

1972.5

--

NP

--

C

--

--

--

2006

2010.1

NP

--

1983.0

--

--

--

C

--

C

--

--

--

1991.5

1978.8

--

1989.0

--

1973

1973

--

1967.3

--

1988.5

--

--

--

1995.5

2005.0

1986.8

--

1983.5

--

--

--

1998.2

--

1994.8

--

--

--

1988.5

Jet pump, not sampled

Poor yield, gas sample not 

possible

Poor yield, gas sample not 

possible

Trace CH4

--

Poor yield, gas sample not 

possible

Poor yield, gas sample not 

possible

--

Slight degassing

Age based on SF6

; CFCs could 

be degraded

Age based on SF6

; CFCs could 

be degraded

Early-mid 1970s age based on 

SF6

, CFC-12, CFC-113

Early-mid 1970s age based on 

SF6

, CFC12, CFC-113

Age estimated using 

CFC-113; CFC-12 and -11 

were contaminated

--

Late 2000s age based on SF6

, 

CFC-11, -12

--

Late 2000s; CFCs could be 

degraded

Mid-late 2000s age based on 

SF6

, and CFC-12, -113

Age based on SF ; CFC-12 age 6

not possible

Modern; degradation of CFCs 

in surface water

Modern; surface water CFC11,-12, and -113 degraded

CFCs slightly higher than 

modern water; CFC-12, 

-113 contaminated

Age uncertain; CFC-11,-12, 

and -113 degraded
32 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Table 4. Concentrations of dissolved gases and age tracers, redox properties, and apparent age of surface-water and groundwater samples from a lake, 

New York, 2009–11.—Continued

[--, not measured; <, less than; E, estimated value below minimum reporting level; NP, age estimate not possible; C, current age; apparent recharge years and ages for 

redox, oxidation–reduction; O , oxygen reducing, NO -, nitrate reducing; Mn, manganese reducing; Fe, iron reducing; SO 2-, sulfate reducing; FeSO , iron- to sulfate- 2 3 4 4

unless otherwise noted; mol/kg, moles per kilogram; pptv, parts per trillion by volume; pmol/kg, picomoles per kilogram; cm3STP/L, cubic centimeters at standard 

Well 

identifier Date

Sample 

time

Dissolved 

oxygen 

(DO)

Sulfide 

(H S)1

2

Methane 

(CH )1

4

Nitrogen 

(N )1

2

Argon 

(Ar)1

Carbon 

dioxide 

(CO )1

2

Redox class 

category

Predominant 

redox 

process

Recharge 

temp 

(degrees 

Celsius)1

Excess 

air 

(cm3

STP/L)1

Tritium, 

picocuries 

per 

liter2

SF in 6

water 

(femtomol/kg)3

Calculated SF 6

partial 

pressure 

(pptv)3

01366400

U1625

U1625

U1629

U1628

U1630

U1631

U1631

U1631

U1647

U7017

U3772

U1645

U1644

4/1/2010

6/24/2009

12/14/2009

6/24/2009

7/2/2009

9/15/2009

9/16/2009

9/16/2009

12/14/2009

4/21/2010

9/20/2011

9/20/2011

9/21/2011

9/21/2011

1000

1100

1000

0800

1000

1700

1000

1001

1630

1300

1200

1200

1200

1200

9.9

3.2

2.1

<0.2

0.6

1.5

1.4

1.4

1.8

<0.2

<0.2

<0.2

0.4

<0.2

--

<0.002

0.093

0.56

1.2

0.012

0.65

0.65

2.3

2.0

0.039

0.006

0.023

0.80

--

<0.001

0.022

15

0.16

<0.001

0.51

0.5

0.34

18

13

6.2

0.054

16

--

19.0

22.5

22.0

31.0

48.0

34.0

33.0

33.0

36.0

25.8

24.0

22.1

23.4

--

0.72

0.8

0.78

0.98

1.4

1.07

1.05

1.05

1.10

0.88

0.83

0.77

0.84

--

4.5

23.1

5.5

1.2

2.2

3.8

3.8

2.2

3.4

13.4

1.3

6.1

2.5

Oxic

Oxic

Mixed (oxic/

methanogenic)

Anoxic

Mixed (oxic/

methanogenic)

Mixed (oxic/

sulfidic)

Mixed (oxic/

methanogenic)

Mixed (oxic/

methanogenic)

Mixed (oxic/

methanogenic)

Anoxic

Anoxic

Anoxic

Anoxic

Anoxic

O2

O2

O2-CH4

Fe(III)-SO4

2--CH4

O2-CH4

O -Mn(IV)-SO 2-

2 4

O -Fe(III)-CH 2 4

O -Fe(III)-CH 2 4

O2-SO4

2--CH4

Mn(IV)-CH4

Mn(IV)-CH4

Fe(III)-CH4

Mn(IV)-CH4

Mn(IV)-CH4

5.4&

8

9.4

7.3

NP

NP

NP

NP

NP

NP

3.0

4.5

7.6

3.3

0

0.65

4.5

3.2

NP

NP

NP

NP

NP

NP

5.4

4.3

3.6

2.9

--

27.2

25.3

19.5

8.3

3.7

2.9

2.6

2.8

<0.3

4.1

0.70

15

8.1

--

2.4

2.85

0.0282

0.13

1.17

0.86

0.50

0.50

0.32

0.0888

0.446

0.141

0.17

--

5.32

4.75

0.05

0.13

1.37

1.37

1.30

0.47

0.26

0.12

0.66

0.24

0.26

1

Analyzed or estimated at the U.S. Geological Survey (USGS) Dissolved Gas Laboratory, Reston, Va.

2

Analyzed at a USGS contract laboratory.

3

Analyzed or estimated at the USGS CFC Laboratory, Reston, Va.

*

Estimated based on mean annual temperature.

&Estimated based on sample temperature.

#

Estimated based on average air temperature for November and December at Wawarsing, N.Y.

 

 

 

 
Table 4 33

springs, and wells in the Wawarsing study area, and for the Rondout Reservoir at the influent to the Rondout–West Branch Tunnel in Lackawack, Ulster County, 

 SF and CFCs have been corrected for excess air; SF , Sulfur hexafluoride; CFC, chlorofluorocarbon; bold text indicates most reasonable apparent age or recharge year; 6 6

 reducing; CH , methanogenic; mixed (Y/Z) indicates waters with different redox ranging from most oxidized (Y) to most reduced (Z); concentrations in milligrams per liter, 4

 temperature and pressure per liter; pCi, picocuries per liter]

SF Ap- 6

parent 

recharge 

year, piston flow3

SF 6

Apparent age, 

piston 

flow3

CFC-11 

corrected 

concentration 

(pmol/kg)3

CFC-12 

corrected 

concentration 

(pmol/kg)3

CFC-113 

corrected 

concentration 

(pmol/kg)3

CFC-11 

Apparent 

age piston 

flow 

(years)3

CFC-12 

Apparent 

age 

piston 

flow 

(years)3

CFC-113 

Apparent 

age 

piston 

flow 

(years)3

CFC-11 

Apparent 

recharge 

year, 

piston 

flow3

CFC-12 

Apparent 

recharge 

year, 

piston 

flow3

CFC-113 

Apparent 

recharge 

year, 

piston 

flow3

Dissolved gas notes Age tracer notes

--

2003.0

2000.5

1952.0

NP

NP

NP

NP

NP

NP

1964.5

1978.3

1970.3

1970.8

--

6.5

9.5

57.5

NP

NP

NP

NP

NP

NP

47.2

33.5

41.5

41.0

5.05

5.25

1.08

0.0857

0.0905

0.284

0.0875

0.0803

0.0925

0

0.157

0.311

0.286

0.131

3.87

3.28

1.75

0.0197

0.0425

0.584

0.0212

0.0167

0.0065

0.429

0.0501

0.243

0.15

0.0716

0.645

0.464

0.154

0

0

0.0533

0.00583

0.0063

0.030

0.075

0.0235

0.0761

0.0665

0.074

27.0

23.15

41.12

55.0

NP

NP

NP

NP

NP

NP

NP

NP

51.2

NP

C

6.65

30.45

62.7

NP

NP

NP

NP

NP

NP

NP

NP

54.5

NP

5.6

21.25

30.29

56.5

NP

NP

NP

NP

NP

NP

NP

NP

NP

NP

1982.8

1986.3

1968.8

1954.5

NP

NP

NP

NP

NP

NP

NP

NP

1960.5

NP

C

2002.8

1979.5

1946.8

NP

NP

NP

NP

NP

NP

NP

NP

1957.2

NP

2008.2

1988

1979.7

1953

NP

NP

NP

NP

NP

NP

NP

NP

NP

NP

Presence of CH4

High CH4

Excess air; presence of CH4

Excess air

Excess air; presence of CH4

Excess air; presence of CH4

Excess air

Excess air

Excess air; presence of CH4

Excess air; presence of CH4

Trace CH4

Excess air; presence of CH4

CFC-12 contaminated; CFC-11 

and -113 degraded

Early 2000s age

Conflicting ages, CFCs could 

be degraded

Late 1940s–1950s age; tracers 

could be degraded

Age uncertain

Age uncertain. Probably a 

mixture of water ages

Age uncertain. CFCs chromatograms appear degraded

Age uncertain. CFCs could be 

slightly degraded

Age uncertain. CFCs are 

degraded

Age uncertain. CFC-11 

degraded

Age uncertain. CFCs are 

degraded

Age uncertain. CFCs are 

degraded

1970 age based on SF ; CFC- 6

113 and possibly CFC-11, 

-12 degraded

Age uncertain. CFCs are 

degraded
34 Preliminary Assessment of Water Chemistry Related to Groundwater Flooding in Wawarsing, New York, 2009–11

Table 5. Dissolved concentrations of trace elements and stable-isotope ratios in surface-water and groundwater samples from a lake, springs, 

County, New York, 2009–11.

[Analytes measured by the U.S. Geological Survey National Water Quality Laboratory unless otherwise noted; concentrations in micrograms per liter, (mg/L) unless 

Be, beryllium; B, boron; Cd, cadmium; Cr, chromium; Co, cobalt; Cu, copper; Fe, iron; Pb, lead; Li, lithium; Mn, manganese; Mo, molybdenum; Ni, nickel; N, nitrogen; 

isotope ratio of hydrogen-2 to hydrogen-1; δ18O, stable isotope ratio of oxygen-18 to oxygen-16, relative to Vienna Standard Mean Ocean Water standard; δ34S, stable 

ganic carbon relative to the Vienna Pee Dee Belemnite standard; SI, saturation index]

Well identifier Date Sample 

time Al Ba Be Cd Cr Co Cu Fe Pb Li Mn 

U1626 12/15/2009 1500 E2.9 26 <0.01 E0.01 0.24 0.23 E0.96 290 <0.03 0.8 79 

U1627 6/23/2009 1200 <4.0 29 <0.02 <0.02 E0.07 0.07 35.1 4 0.81 1.6 0.2 

U1627 4/1/2010 0900 11.8 24 <0.01 <0.02 E0.11 0.05 E0.78 <6 <0.03 1.2 <0.3 

U1637 8/31/2010 1400 190 140 0.014 0.029 0.34 0.3 <1.0 420 0.26 2.9 630 

U1641 4/20/2010 1300 <17.0 83 <0.06 <0.10 <0.60 2.2 <5.0 92 <0.15 4.3 130 

U1641 4/20/2010 1301 <17.0 84 <0.06 <0.10 <0.60 2.0 <5.0 91 <0.15 4.2 130 

U1663 8/31/2010 1400 7.8 54 E0.01 0.04 <0.120 0.068 E0.92 2.3 <0.03 90 41 

U1673 11/30/2011 1200 <2.2 240 <0.006 <0.02 <0.07 0.08 2.8 24 0.15 2.9 260 

U1670 11/30/2011 1000 <2.2 180 <0.006 <0.02 <0.07 0.03 0.95 34 0.08 3 190 

U1632 9/14/2009 1730 E3.6 13 <0.02 E0.01 0.19 0.08 <1.0 <4 <0.06 <1.0 16 

U1633 9/15/2009 1200 <4.0 15 <0.02 0.03 0.33 0.04 <1.0 E2 <0.06 E0.7 18 

U1667 9/15/2009 1400 20 14 E0.02 E0.02 0.21 0.07 <1.0 53 0.11 E0.7 19 

U1668 7/1/2009 1300 15.9 14 <0.02 <0.02 <0.12 0.1 2.5 248 <0.06 E0.7 21 

U1666 6/23/2009 1400 <4.0 25 <0.02 <0.02 <0.12 0.08 E0.77 <4 <0.06 1.8 <0.2 

U1666 3/31/2010 1600 E1.9 23 <0.01 <0.02 E0.08 0.06 <1.0 <6 <0.03 2.3 <0.3 

U1665 3/31/2010 1200 7.9 14 <0.01 E0.01 E0.10 0.03 <1.0 6 E0.02 <0.4 9.8 

Lippman Lake effluent 6/24/2009 1330 -- -- -- -- -- -- -- -- -- -- -- 

Lippman Lake effluent 7/2/2009 1300 28 10 <0.02 E0.01 0.14 0.10 <1.0 317 0.16 E0.7 51 

Lippman Lake effluent 9/1/2009 1230 -- -- -- -- -- -- -- -- -- -- -- 

Lippman Lake effluent 9/16/2009 1300 34 19 <0.02 <0.02 E0.10 0.08 <1.0 34 <0.06 3.7 2.1 

Lippman Lake effluent 10/13/2009 1515 -- -- -- -- -- -- -- -- -- -- -- 

Lippman Lake effluent 12/15/2009 1000 140 6 <0.01 <0.02 <0.12 0.12 <1.0 142 0.05 1.2 86 

Lippman Lake effluent 4/1/2010 1200 58 7 <0.01 <0.02 E0.06 0.49 <1.0 58 E0.03 1.6 48 

01366400 6/23/2009 0930 6.1 26 <0.02 <0.02 <0.12 E0.01 1.3 E4 <0.06 <1.0 1.7 

01366400 9/1/2009 1030 26 29 0.02 E0.02 E0.08 0.02 18.1 6 0.34 E0.6 3.2 

01366400 10/13/2009 1420 -- -- -- -- -- -- -- -- -- -- -- 

01366400 10/13/2009 1425 -- -- -- -- -- -- -- -- -- -- -- 

01366400 12/22/2009 1110 4.8 26 E0.01 <0.02 0.18 0.03 E0.94 E5 E0.02 0.4 1.5 

01366400 4/1/2010 1000 17 30 E0.01 0.02 <0.12 0.02 E0.86 8 E0.02 0.5 5.2 

U1625 6/24/2009 1100 <4.0 42 <0.02 <0.02 <0.12 0.02 10.7 <4 0.23 7.2 0.2 

U1625 12/14/2009 1000 <3.4 130 <0.01 E0.01 <0.12 0.37 1.1 E5 0.44 20 13 

U1625 4/7/2011 1900 11.2 24 <0.006 <0.016 0.11 0.068 1.1 54 0.028 4.4 7.6 

U1629 6/24/2009 0800 <20.0 230 <0.10 <0.10 <0.60 <0.10 <5.0 146 <0.30 320 260 

U1629 4/7/2011 1100 7.1 140 <0.006 <0.02 <0.06 0.17 <0.5 1,500 0.062 55 450 

U1629 4/7/2011 0900 3.2 120 <0.006 0.016 0.11 0.1 <0.5 570 0.22 20 380 

U1628 7/2/2009 1000 E3.5 32 <0.02 <0.02 E0.09 0.12 E0.69 17 E0.04 5.2 2.0 

U1630 9/15/2009 1700 <4.0 49 <0.02 <0.02 <0.12 0.11 <1.0 260 <0.06 310 81 

U1631 9/16/2009 1000 400 43 <0.02 0.02 <0.12 0.20 <1.0 230 <0.06 100 600 

U1631 9/16/2009 1001 <4.0 44 <0.02 0.02 <0.12 0.19 <1.0 230 <0.06 101 660 

U1631 12/14/2009 1630 <3.4 43 <0.01 0.35 <0.12 0.60 <1.0 370 <0.03 91 490 

U1647 4/21/2010 1300 <34 97 <0.12 <0.20 <1.2 2.2 <10.0 40 <0.30 320 300 

U7017 9/20/2011 1200 <1.7 240 0.009 <0.02 <0.06 <0.02 <0.5 1,800 0.032 120 150 

U3772 9/20/2011 1200 1.8 1,120 <0.006 <0.02 0.077 <0.02 <0.5 91 <0.02 80 26 

U1645 9/21/2011 1200 4.2 130 <0.006 <0.02 0.19 0.03 <0.5 630 <.01 29 150 

U1644 9/21/2011 1200 6.6 480 0.008 <0.02 <0.06 <0.02 <0.5 94 <0.015 730 330 

1

Analyzed at the U.S. Geological Survey (USGS) Isotope Laboratory, Menlo Park, Calif.

2

Analyzed at the USGS Reston Stable Isotope Laboratory, Reston, Va.
Table 5 35

and wells in the Wawarsing study area, and for the Rondout Reservoir at the influent to the Rondout–West Branch Tunnel in Lackawack, Ulster 

 otherwise noted; --, not measured; NA, not applicable; <, less than; E, estimated value below minimum reporting level; Al, aluminum; Sb, antimony; As, arsenic; Ba, barium; 

 Se, selenium; Ag, silver; Sr, strontium; Tl, thallium; U, uranium; V, vanadium; Zn, zinc; 87Sr/86Sr, stable isotope ratio of strontium-87 to strontium-86; d, delta; δ2H, stable 

 isotope ratio of sulfur-34 to sulfur-32 of sulfate relative to the Vienna Canyon Diablo Troilite standard; δ13C of DIC, stable isotope ratio of C-13 to C-12 of dissolved inorMb Ni Ag Sr Tl V Zn Sb As B Se U

δ2H in 

water 

(per mil)

δ18O in 

water 

(per mil)

δ34S of 

2- SO 4

(per mil)

δ13C of 

DIC 

(per mil)

87Sr/86Sr 

(per mil)1

M

0.3

0.2

6.6

1.0

1.1

7.5

0.48

0.68

M

M

M

0.1

0.1

0.2

M

--

M

--

0.5

--

M

M

M

M

--

--

M

M

0.5

1.1

0.52

0.6

1.0

1.0

1.1

2.9

9.9

10.9

11.8

3.2

0.12

0.16

1.5

2.0

0.89

0.48

0.34

0.97

1.7

1.5

0.28

0.30

0.26

0.33

0.42

0.64

0.22

0.47

0.38

0.37

--

0.36

--

0.77

--

0.52

0.43

0.34

0.45

--

--

0.48

0.34

0.37

3.3

2.3

<0.60

8.4

4.4

0.81

0.57

1.4

1.3

3.9

2.5

<0.09

<0.09

0.33

0.15

<0.010

<0.008

M

<0.01

<0.1

<0.1

<0.01

<0.005

<0.005

<0.008

<0.008

<0.008

<0.008

<0.008

<0.010

<0.010

--

<0.008

--

<0.008

--

<0.010

<0.010

<0.008

M

--

--

<0.010

<0.010

<0.008

<0.010

<0.005

<0.040

<0.005

<0.005

<0.008

M

M

M

M

<0.1

<0.005

<0.005

<0.005

<0.005

52

160

130

1,400

1,220

1,200

340

130

120

35

22

23

55

130

150

19

--

28

--

120

--

44

47

16

16

--

--

19

17

150

1,000

90

590

280

230

380

--

17,700

17,800

19,800

13,800

180

580

850

2,170

E0.01

<0.04

<0.02

<0.02

<0.10

<0.10

<0.02

<0.01

<0.01

<0.04

<0.04

<0.04

<0.04

<0.04

<0.02

<0.02

--

<0.04

--

<0.04

--

<0.02

<0.02

<0.04

<0.04

--

--

<0.02

<0.02

<0.04

<0.02

<0.01

<0.20

<0.01

<0.01

<0.04

<0.04

<0.04

<0.04

<0.02

<0.20

<0.010

<0.01

<0.01

<0.01

<0.16

0.24

0.22

0.35

<0.80

<0.80

<0.16

<0.080

<0.080

E0.09

<0.16

E0.15

1.4

E0.10

E0.09

E0.09

--

0.26

--

E0.13

--

<0.16

<0.16

<0.16

<0.16

--

--

<0.16

<0.16

<0.16

E0.11

<0.08

<0.80

<0.80

<0.80

1.6

<0.16

E0.12

E0.12

0.34

1.9

<0.080

<0.080

<0.080

0.10

E1.4

3.2

<2.8

E2.2

<14

<14

<2.8

8.3

6.2

2,000

5,300

E2.0

<2.0

<2.0

<2.8

<2.8

--

2.0

--

<2.0

--

<2.8

<2.8

2.3

5.1

--

--

E1.6

E2.1

E1.8

3.7

1.6

<10.0

2.1

62

<2.0

2.1

<2.0

<2.0

<2.8

<28.0

3.4

1.8

2.9

<1.4

E0.03

0.10

0.08

0.27

E0.23

E0.25

0.5

<0.03

<0.03

<0.04

<0.04

<0.04

E0.02

0.09

0.07

0.07

--

E0.02

--

0.13

--

E0.03

0.06

E0.03

0.05

--

--

E0.04

E0.03

0.05

0.12

0.063

<0.20

<0.027

<0.027

0.06

<0.04

<0.04

<0.04

<0.05

<0.54

<0.027

<0.03

<0.03

<0.03

0.13

0.37

0.27

2.5

2.1

2.0

1.6

5.9

6.4

0.17

0.17

0.26

0.37

0.33

0.24

0.18

--

0.53

--

2.3

--

0.21

0.34

0.18

0.27

--

--

0.28

0.18

0.18

0.25

0.2

<0.30

0.027

0.057

0.97

1.4

3.9

4.0

6.1

8.3

1.2

0.67

10

5.3

6

15

11

10

E9

E9

280

6

6

5

7

6

E3

19

13

9

--

4

--

17

--

6

9

5

4

--

--

4

4

11

44

6.9

65

22

18

21

284

97

112

92

269

190

150

43

290

0.06

0.40

0.35

E0.036

<0.20

<0.20

E0.026

<0.030

<0.030

0.09

E0.05

0.07

E0.06

0.3

0.25

0.06

--

0.10

--

0.08

--

E0.03

0.05

<0.06

E0.05

--

--

0.04

E0.03

0.10

0.16

0.091

E0.24

<0.03

<0.03

0.47

<0.06

E0.03

<0.06

<0.04

<0.40

<0.030

<0.030

<0.030

<0.030

0.01

0.76

0.86

1.2

0.29

0.27

0.092

0.20

0.30

E0.01

<0.01

E0.00

0.03

0.46

0.91

E0.01

--

0.01

--

0.32

--

0.02

0.04

0.01

0.02

--

--

0.01

0.02

0.33

2.00

0.09

0.04

0.16

0.22

0.77

0.12

0.58

0.64

0.56

0.48

0.006

0.03

0.34

0.11

-52.9

-51.3

-71.0

-59.0

-58.4

--

-61.9

-55.2

-55.7

-56.2

-55.7

-54.9

-54.0

-50.4

-68.5

-67.9

-49.0

-47.8

-41.9

-40.1

-40.2

-56.7

-67.2

-58.4

-55.3

-55.9

-56.0

-55.7

-62.7

-57.9

-54.5

-63.4

-56.2

-55.9

-55.9

-61.8

-67.8

-64.4

-64.6

-64.9

-64.8

-60.8

-59.0

-58.2

-63.8

-8.44

-8.15

-10.7

-9.24

-9.23

--

-9.34

-8.97

-8.97

-8.89

-8.96

-8.82

-8.71

-8.01

-10.4

-10.5

-7.95

-7.60

-6.27

-5.99

-6.00

-8.98

-10.3

-9.14

-8.76

-8.77

-8.70

-8.64

-9.58

-9.08

-8.61

-9.75

-8.99

-8.86

-8.86

-9.70

-10.3

-10.1

-10.0

-9.98

-10.1

-9.52

-9.26

-8.97

-9.77

9.36

-2.95

-3.72

-1.95

0.34

0.48

8.8

0.61

-5.08

2.23

3.09

3.36

3.72

-6.84

-6.97

2.79

--

1.76

--

-3.17

--

3.71

1.15

3.36

4.16

--

--

4.26

4.16

-8.44

-11.5

--

0.99

--

--

25.4

28.6

25.3

25.3

25.7

31.6

--

--

-9.66

-1.88

-22.1

-16.6

-16.7

-14.0

-11.0

-11.3

-14.0

--

--

--

--

-17.7

-15.5

-23.5

--

-8.17

--

--

--

-18.2

-13.1

-13.8

--

--

-13.9

-12.9

-12.7

-15.1

--

-13.1

--

--

-9.68

--

--

--

-12.0

-16.6

-11

-17.3

-14.3

-17.5

0.71214

0.71139

0.71136

0.70909

0.70916

0.70913

0.71164

0.7108

0.71069

0.71227

0.71176

0.71196

0.71223

0.71552

0.71148

0.71352

--

0.71209

--

0.71125

--

0.71259

0.7119

0.71416

0.71392

--

--

0.71419

0.71424

0.71416

0.712

0.71198

0.71158

0.71129

0.71151

0.70983

0.70919

0.70901

0.70900

0.70902

0.70947

0.71277

0.71367

0.71136

0.71195
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