U.S. Department of the Interior

U.S. Geological Survey

In Cooperation with the Clifton Park Water Authority

Water-Resources Investigations Report 01-4104

Ground-Water Resources of the Clifton Park Area, 

Saratoga County, New York
Cover photo: View of golf course production well number one (Sa-1273) looking south.
Ground-Water Resources of the Clifton Park Area, 

Saratoga County, New York

BY PAUL M. HEISIG

U.S. GEOLOGICAL SURVEY

WATER-RESOURCES INVESTIGATIONS REPORT 01-4104

In cooperation with the Clifton Park Water Authority

Troy, New York

2002
U.S. DEPARTMENT OF THE INTERIOR

Gail A. Norton, Secretary

U.S. GEOLOGICAL SURVEY

For additional information write to: Copies of this report can be purchased

from:

U.S. Geological Survey

Branch of Information Services

Box 25286 

Denver, CO 80225-0286

The use of firm, trade, and brand names in this report is for identification purposes 

only and does not constitute endorsement by the U.S. Geological Survey.

Charles G. Groat, Director

District Chief

U.S. Geological Survey

425 Jordan Road

Troy, NY 12180

ii
Contents III

CONTENTS

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

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

Purpose and Scope ...................................................................................................................................................... 3

Acknowledgments ...................................................................................................................................................... 3

Hydrogeologic Framework.................................................................................................................................................... 5

Lacustrine Sand Aquifer ............................................................................................................................................. 6

Colonie Channel Aquifer and Adjacent Areas ............................................................................................................ 6

Alluvial Aquifer .......................................................................................................................................................... 7

Chemical Composition of Ground Water ............................................................................................................................. 8

Calcium-Magnesium-Bicarbonate Water Type ........................................................................................................... 8

Calcium-Sodium-Bicarbonate-Chloride Water Type ........................................................................................ 10

Sodium-Calcium-Bicarbonate-Chloride Water Type ........................................................................................ 10

Calcium-Bicarbonate-Sulfate Water Type ........................................................................................................ 10

Sodium-Calcium-Bicarbonate Water Type ................................................................................................................. 11

Sodium-Bicarbonate Water Type ................................................................................................................................ 12

Ground-Water Levels ............................................................................................................................................................ 12

Unconfined Conditions ............................................................................................................................................... 12

Confined Conditions ................................................................................................................................................... 12

Responses to Pumping Wells ...................................................................................................................................... 13

Water Levels in the Colonie Channel Aquifer, August-September 1998 ................................................................... 13

Conceptual Model of Ground-Water Flow within the Lacustrine Sand and Colonie Channel Aquifers .............................. 15

Lacustrine Sand Aquifer ............................................................................................................................................. 15

Colonie Channel Aquifer ............................................................................................................................................ 15

Peripheral Channel Areas ................................................................................................................................. 17

Central Channel Area ........................................................................................................................................ 17

Summary ............................................................................................................................................................................... 19

References Cited.................................................................................................................................................................... 20

FIGURES

1. Map showing location and pertinent geographic features of the Clifton Park study area and vicinity in southern 

Saratoga County, New York .............................................................................................................................................. 2

2. Map showing location of the Colonie Channel aquifer, including the central channel area and peripheral 

channel areas .................................................................................................................................................................... 4

3. Piper diagram of six ground-water types identified from complete major-ion analyses, Clifton Park area, 1993-98 ...... 9

4. Hydrograph of ground-water levels in the lacustrine sand aquifer at USGS observation well Sa-1285, Clifton Park, 

N.Y., March 1997 through February 1998 ....................................................................................................................... 12

5. Vertical section showing generalized conceptual model of ground-water-flow directions, chemical composition of 

ground water, and water levels within the lacustrine sand and Colonie Channel aquifers in the Clifton Park area......... 16

6. Water-level trends and annual pumpage at the Plank wellfield, 1973-99.......................................................................... 18

 PLATE (in pocket)

1A.1-3 Hydrogeologic framework of the Clifton Park area, Saratoga County, New York: 

1. Map showing thickness and extent of lacustrine sand aquifer, including location of medium to coarse 

lacustrine-deltaic sand and gravel, and extent of the local alluvial aquifer along the Mohawk River.

2. Vertical section A-A ́ showing relations among hydrogeologic units in the Clifton Park study area.

3. Map showing thickness and extent of the Colonie Channel aquifer and its hydrogeologic settings, including the 

presence or absence of confining units, and their type and thickness.
IV Contents

1B. Ground-water levels and chemical composition of ground water in the Clifton Park area, N.Y.:

1. Map showing chemical composition of ground water (1993-98) and ground-water levels 

(August-September 1998) within the Colonie Channel aquifer.

2. Vertical section A-A ́ showing approximate distribution of chemical water types and water levels 

within the lacustrine sand and Colonie Channel aquifers. 

CONVERSION FACTORS AND VERTICAL DATUM

Multiply By To obtain

inch (in.) 25.4 millimeter

foot (ft) 0.3048 meter 

mile (mi) 1.609 kilometer 

square mile (mi2)2.59 square kilometer

gallon (gal) 3.785 iter

Other Units

milligram per liter (mg/L)

microgram per gram (mg/g)

microgram per kilogram (mg/kg)

microsiemen per centimeter at 25° C (mS/cm)

greater than or equal to (>)

Sea level: In this report "sea level" refers to the National Geodetic Vertical 

Datum of 1929 (NGVD of 1929)—a geodetic datum derived from a general 

adjustment of the first-order level nets of the United States and Canada, 

formerly called Sea Level Datum of 1929.
Abstract 1

Ground-Water Resources of the Clifton Park Area, 

Saratoga County, New York 

By Paul M. Heisig

ABSTRACT

Ground water is the sole source of public 

water supply for Clifton Park, a growing suburban 

community north of Albany, New York. 

Increasing water demand, coupled with concerns 

over ground-water quantity and quality, led the 

Clifton Park Water Authority in 1995 to initiate a 

cooperative study with the U.S. Geological 

Survey to update and refine the understanding of 

ground-water resources in the area.

Ground-water resources are largely 

associated with three aquifers in the eastern half 

of the area. These aquifers overlie or encompass 

the Colonie Channel, a north-south-oriented 

bedrock channel that is filled primarily with 

lacustrine glacial deposits. The three aquifers are: 

(1) an unconfined lacustrine sand aquifer, (2) the 

Colonie Channel aquifer, which is confined 

within the deepest parts of the channel and 

variably confined and unconfined within the 

shallower, peripheral channel areas, and (3) an 

unconfined alluvial aquifer beneath the Mohawk 

River flood plain, which represents the southern 

limit of the study area. The lacustrine sand aquifer 

has little potential for large-scale withdrawals 

because it is predominantly fine grained and is 

susceptible to contamination from human 

activities at land surface. Water from this aquifer 

can, however, recharge the underlying peripheral 

parts of the Colonie Channel aquifer where 

hydraulic connections are present. The Colonie 

Channel aquifer consists of thin sand and gravel 

and (or) shallow, fractured bedrock over much of 

the channel area; discontinuous deposits of 

thicker (more than 20 feet) sand and gravel are 

common in the peripheral channel areas. The 

deepest, or central, channel area of this aquifer is 

isolated from the overlying lacustrine sand aquifer 

by a continuous lacustrine silt and clay unit, 

which is the primary channel-fill deposit. The 

most productive areas of the Colonie Channel 

aquifer are typically the shallow peripheral areas, 

where conditions range from unconfined to 

confined. The most productive aquifer within the 

area is the alluvial aquifer, which is sustained to 

an unknown extent by induced infiltration of 

Mohawk River water.

The chemical composition of ground water 

within the Clifton Park area varies widely in 

response to hydrogeologic setting, pumpage, and 

contamination from human activities. These 

chemical differences can be used to deduce 

ground-water flow paths within and between the 

unconfined and confined areas of the aquifer 

system. Six water types are defined; three are 

naturally occurring and three are the result of 

human activities.

Precipitation that infiltrates the land surface is 

the sole source of recharge to the lacustrine sand 

aquifer; precipitation also recharges the alluvial 

aquifer and unconfined parts of the Colonie 

Channel aquifer. Ground-water withdrawals from 

confined or unconfined peripheral areas of the 

Colonie Channel aquifer induce flow from 

recharge areas, from the underlying bedrock, or 

from other confined aquifer areas.

The rate of recharge to the confined central 

area of the Colonie Channel aquifer appears to be 

low. Potentiometric levels as much as 100 feet 

below water-table levels in the overlying 

lacustrine sand aquifer indicate two large 
2 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York

Round

Lake

Stony Creek

Reservoir

Ballston

Lake

Hudson

Kill

Mohawk

Dwaas

River

River

Ferry

Rt. 146A

Road

Vischer

Rt. 146

Adirondack Northway

I - 87

TOWN

OF

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TOWN

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WATERFORD

TOWN

OF

CLIFTON PARK

R

E

N

S

SELAER

COUNTY

SARATOGA

COUNTY

ALBANY

COUNTY

SARATOGA

S CHENECTADY

COUNTY

COUNTY

0 1

0 1 2 3 Kilometers

2 3 Miles

42°54'

73°48' 42'

48'

Study area

Saratoga

County

NEW YORK

Study

Area

depressions in the potentiometric surface; these 

depressions indicate that withdrawals from this 

aquifer have cumulatively exceeded the recharge 

rates. Localized recharge of the central channel 

area apparently occurs from two peripheral 

channel areas that are characterized by zones of 

elevated water levels and (or) by water chemistry 

that differs from those within the central channel 

area. Recharge from, or hydraulic connection 

with, adjoining segments of the Colonie Channel 

aquifer to the north and south is likely, but the 

potential for significant recharge is low because 

the aquifer is thin and poorly permeable.

INTRODUCTION

The Town of Clifton Park, in southern Saratoga 

County (fig. 1), is a suburban community whose 

population grew five-fold from the early 1960's to 

about 30,000 in 1990 (Capital District Regional 

Planning Commission, 1994). Improved access to jobs 

in Albany County to the south since the opening of the 

southern section of the Northway (I-87) in 1961 has 

made the town a desirable bedroom community. The 

relatively level land with well-drained sandy soils in 

the eastern half of the town is favorable for residential 

development. Residential and commercial 

development has continued through the 1990's and has 

Figure 1. Location and pertinent geographic features of the Clifton Park study area, southern 

Saratoga County, New York.
3

been paralleled by an increased water demand. Ground 

water is the town’s sole source of public water supply. 

In 1997, Clifton Park public-supply wells pumped 

more than 1 billion gallons of water (D. Connor, 

Clifton Park Water Authority, written commun., 1999).

Early residential developments were served 

mostly by low-yield, shallow, drilled wells or 

wellpoints and large-diameter infiltration wells or 

galleries. These privately owned systems were plagued 

by low water pressure and high turbidity, however, and 

also were susceptible to contamination from human 

activities at land surface. As development continued, 

new ground-water sources were sought. From the late 

1960’s through the early 1990’s, deeper, more 

productive aquifer areas consisting of glacial deposits 

and shallow fractured bedrock were identified in and 

around the Colonie Channel (fig. 2), a buried bedrock 

channel of a former river beneath the eastern part of 

town (Simpson, 1949; Dineen and Hanson, 1983). The 

Colonie Channel aquifer subsequently became the 

primary source(s) of water for the town; initial reports 

from the most productive wellfields indicated 

sustainable yields that ranged between 600 and 1,000 

gallons per minute (gal/min) (Dunn Geoscience 

Corporation, 1979, 1985b). The quantity and chemical 

quality of water withdrawn varies widely among the 

wellfields, however, and water-level declines in deep 

confined areas over the years indicate that, in general, 

ground-water withdrawals have exceeded the rate of 

aquifer recharge. The most common water-quality 

complaints from consumers supplied by water from 

unconfined or locally confined areas of the aquifer 

have been excessive iron and (or) hardness.

Increasing water demands have necessitated 

exploration for additional water supplies. Most 

recently (1996), shallow alluvial deposits along the 

Mohawk River in the southern part of town (pl. 1A.1) 

have been tapped as a major new source of water. 

Initial well yields ranging from 600 to 1,000 gal/min 

are apparently sustained in part by induced infiltration 

of water from the Mohawk River (C.T. Male 

Associates, P.C., 1996, 1999).

In 1991, the Town of Clifton Park established 

the Clifton Park Water Authority (CPWA) to 

improve water service to consumers. Existing watersupply systems were consolidated and 

interconnected, and a program of infrastructure 

upgrades, water-quality improvement, and waterresource evaluation was instituted. 

In 1995, the U.S. Geological Survey (USGS), in 

cooperation with the CPWA, began a study to refine 

previous conceptual models of ground-water 

occurrence and to conceptualize the availability and 

chemical quality of ground water in the Clifton Park 

area. This information is critical to support decisions 

regarding the management and protection of local 

ground-water resources in the study area and in similar 

hydrogeologic settings within the region. Whereas 

previous studies of local geology and hydrogeology 

(Dineen and Hanson, 1983; Waller, 1983; Reynolds, 

1985) have provided information on the hydrogeologic 

framework and conceptualization of water resources in 

the Clifton Park area, this study incorporates waterlevel and water-quality data collected by USGS and 

CPWA, recent data from drillers’ logs, several groundwater exploration and wellfield-analysis reports by 

private consultants, and water-quality data on file at 

the New York State Department of Health. During the 

study, latitude-longitude, well-construction, and 

hydrogeologic data from 214 wells (local well 

numbers Sa-1287 through Sa-1500) were added to the 

USGS National Water Information System (NWIS) 

database; these data are available upon request from 

the USGS. A local well number prefixed by “Sa” (for 

Saratoga County) is listed after the first reference to 

each well discussed in the text. 

Purpose and Scope

This report (1) documents the hydrogeologic 

framework, ground-water chemistry, and groundwater levels in the Clifton Park area, with emphasis on 

the Colonie Channel aquifer on the eastern side of 

town, and (2) presents a refined conceptual model of 

the aquifer system.

Maps and a vertical section depict (1) thickness of 

the lacustrine sand and extent of the alluvial aquifer, 

and (2) thickness of the Colonie Channel aquifer 

(glacial deposits only) and the extent and type of 

overlying confining units. A map and a vertical section 

show ground-water levels (August and September 

1998) and the distribution of water types (1993-98) 

within the Colonie Channel aquifer.

Acknowledgments

The author thanks the many property owners and 

businesses that granted permission for water-level 

Introduction
4 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York

?

? TOWN

OF

COLONIE

TOWN

OF

HALFMOON

TOWN

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CLIFTON PARK

TOWN

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BALLSTON

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Route 146 Ro

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Route 146

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Base from New York State Department of Transportation Digital Planimetric Maps, 1:24,000.

Burnt Hills 1991, Round Lake 1991, Schenectady 1993, Niskayuna 1992

UNCONSOLIDATED

BEDROCK

TOWN BOUNDARY

COUNTY BOUNDARY

EXPLANATION

UNCONFINED AREAS:

0 1

0 2 KILOMETERS

2 MILES

NEW YORK

Saratoga

County

Study

Area

42°54'

73°54' 48'

48'

Figure 2. Location of the Colonie Channel aquifer, including the central channel and the peripheral 

channel areas, Clifton Park, New York.
5

monitoring and water-sample collection from their 

wells. Douglas Connor and Walter Schlesier of the 

Clifton Park Water Authority provided historical 

pumpage, water-level, and other ancillary data, 

facilitated access to sites, provided field personnel for 

collection of ground-water data, and measured the 

sulfate concentration in selected ground-water 

samples. The late well driller, Richard Ferraioli, of 

Dick Ferraioli, Inc., provided many well logs, field 

assistance in locating wells, and information on 

drilling conditions at several sites. Eric Hanson, of 

Continental Placer, Inc., provided several well logs, 

assisted in well location, and provided information on 

subsurface conditions in the area. George Hodgson, of 

the Saratoga Environmental Management Council, 

provided recent well logs. Janice Baldwin of Hawk 

Drilling Co., Inc., also provided well-log information.

HYDROGEOLOGIC FRAMEWORK

The Towns of Clifton Park and Halfmoon (fig. 1) 

are underlain by structurally deformed, fractured 

Ordovician shale and sandstone (Fisher and others, 

1970; Kidd and others, 1995) that are overlain in most 

areas by Pleistocene (glacial) and Recent sediments. 

The buried bedrock surface is uneven and has been 

shaped by the erosive action of rivers, streams, and 

glacial ice. The most pronounced bedrock-surface 

feature is the Colonie Channel (Simpson, 1949), 

which runs north-south through the eastern half of 

Clifton Park (fig. 2); it consists of a broad, shallow 

channel about 3 mi wide that is bounded by local 

bedrock-cored hills, and a 1-mi-wide inner channel, 

generally defined by lacustrine silt and clay 

thicknesses greater than 60 ft (pl. 1A.2-3). The 

deepest part of the channel is typically 150 to 200 ft 

deeper than the surrounding bedrock surface and is 

buried beneath as much as 314 ft of glacial deposits 

(Dineen and Hanson, 1983; Reynolds, 1985). The 

western side of the town has relatively low bedrocksurface relief (generally less than 50 ft) and thin 

overlying Pleistocene and Recent deposits (typically 

less than 50 ft thick). 

Areas where bedrock is overlain by minimally 

saturated or unsaturated unconsolidated deposits are 

generally poor sources of water in terms of quantity 

and quality. Water is available primarily from fracture 

openings within the bedrock; thus, only small amounts 

of water can be held in storage. Withdrawal of water 

from water-bearing fractures can result in a large cone 

of depression that may extend to, and interconnect 

with, near-surface fractures, which are vulnerable to 

contamination from surface sources. Wells that tap 

deep fractures may contain high sodium 

concentrations (200 mg/L).

Bedrock is successfully tapped as a water source 

where it is overlain by saturated unconsolidated 

deposits, particularly within sections of the Colonie 

Channel. Many wells tap thin, permeable zones of 

fractured shale just below the bedrock surface or in 

shale gravel just above it. These permeable bedrock 

zones typically are in hydraulic connection with local, 

overlying permeable zones of glacial ice-contact 

deposits and may provide a hydraulic interconnection 

among otherwise isolated permeable ice-contact 

deposits within the channel.

The thickest glacial deposits are in and adjacent 

to the Colonie Channel; they include (1) till, directly 

deposited by active ice; (2) coarse-grained ice-contact 

deposits deposited by meltwaters within, beneath, or 

adjacent to stagnant ice; and (3) lacustrine silt and 

clay, lacustrine sand, and deltaic sand and gravel 

deposited in proglacial lakes during deglaciation. The 

glacial history of the area has been described by 

LaFleur (1965, 1979), Hanson (1977), and Dineen and 

Hanson (1983). The typical sequence of glacial 

deposits, in ascending order, from top of bedrock is: 

till and (or) ice-contact deposits overlain by lacustrine 

silt and clay, which in turn is overlain by lacustrine 

sand and possibly deltaic sand and gravel. One or 

more of these units can be missing in any given area.

The study area contains two glacial aquifers: (1) 

the lacustrine sand aquifer, which is an unconfined 

(water-table) aquifer composed of saturated lacustrine 

sand and deltaic sand and gravel deposits, and (2) the 

Colonie Channel aquifer, which is a mostly confined 

aquifer composed of ice-contact sand and gravel 

deposits in hydraulic connection with thin, permeable 

areas of fractured bedrock or bedrock-derived gravel 

at or near the bedrock surface. Much of this aquifer is 

overlain and confined by lacustrine silt and clay and 

(or) till units within the center of the Colonie Channel.

A third aquifer, composed of productive fluvial 

sand and gravel, underlies part of the Mohawk River 

flood plain at the southern end of Clifton Park (pl. 

1A.1). It is overlain by about 5 to 15 ft of alluvium, 

which ranges from silty clay to fine-to-medium sand. 

Other alluvium deposited by small streams and other 

Recent deposits, such as aeolian sand, or peat and 

muck, do not provide useful amounts of water because 

Hydrogeologic Framework
6 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York

they are too thin, have low permeability, and (or) are 

not fully saturated.

Lacustrine Sand Aquifer

The lacustrine sand aquifer is unconfined and is 

present mostly in the area underlain by the Colonie 

Channel in the eastern half of Clifton Park (pl. 1A.1-

2). Lacustrine and aeolian sand deposits in this area 

are thin and have little saturated thickness, although 

they are widespread in other parts of Clifton Park. The 

aquifer material was deposited by floodwaters from 

the west (Dineen and Hanson, 1983, Wall, 1995) that 

scoured and incised channels in till and bedrock on the 

western side of town and deposited lacustrine-deltaic 

and blanket-sand deposits as much as 100 ft thick in 

proglacial lake environments on the eastern side of 

town (pl. 1A. 1-2).

The lacustrine-deltaic deposits are coarsest 

(medium to coarse sand and fine gravel) in the area 

just east of where waters from the Iromohawk River, 

which preceded the present-day Mohawk River, 

breached low points among the till and bedrock hills 

along the western side of the Colonie Channel 

(pl. 1A.1; Wall, 1995). One of the largest and most 

productive of these deltaic deposits is about 25 ft thick 

and underlies the Shenendehowa Central School 

campus along Rt.146 (pl. 1A.1). This material was 

apparently deposited by Iromohawk floodwaters that 

flowed eastward through the channel now occupied by 

the Dwaas Kill west of Vischers Ferry Road (pl. 1A.1). 

The lacustrine sands farther east of the breach areas 

are typically fine grained with some silt and become 

siltier with depth.

Ground-water levels in the lacustrine sand 

aquifer generally are less than 20 ft below land 

surface in areas of low relief but may be as much as 

60 ft below land surface in areas where the stream 

channels are deeply incised or where hydraulic 

interconnection with the underlying channel aquifer 

induces downward leakage from the lacustrine sand 

aquifer. The fine grain-size of the aquifer material has 

largely restricted pumping; infiltration of fine sand 

and silt into well pumps has resulted in the 

abandonment of several wellfields and precludes use 

of conventional screened wells in most of the aquifer. 

Reported yields from infiltration wells and galleries 

range from 20 to 80 gal/min, whereas multiple wellpoint installations have provided 100 to 300 gal/min. 

Shallow domestic well points commonly provide 

enough water for lawn watering.

The lacustrine sand aquifer is most productive 

where it contains saturated deltaic sand and gravel 

(pl. 1A.1). Screened wells have been used successfully 

in several of these areas, including the primary 

production well for the Shenendehowa Central School 

campus (300 gal/min) and the Elnora well field (at 

least 400 gal/min) (pl. 1A.1). The primary concern in 

withdrawing water from this aquifer is the high 

potential for contamination from nearby human 

sources, such as wastewater disposal, fertilizer and 

pesticide application, road-salt storage and application, 

and leaking underground fuel-storage tanks. 

Colonie Channel aquifer and adjacent 

areas

The Colonie Channel aquifer, also referred to as 

the “channel aquifer” herein, has been previously 

referred to as the “confined aquifer” (Reynolds, 

1985) or “deep aquifer” (Waller, 1983). It has been a 

major source of ground water for Clifton Park since 

the late 1960's and consists of discontinuous areas of 

(1) permeable ice-contact deposits generally 

overlying bedrock, (2) fractured bedrock (near the 

bedrock surface), or (3) bedrock-derived shaley 

gravel overlying the bedrock surface (pl. 1A.2-3). 

The distribution, permeability, and degree of 

hydraulic interconnection among these materials are 

locally variable. These deposits are confined by 

lacustrine silt and clay or till but may be locally 

unconfined (pl. 1A.2-3) in peripheral channel areas 

(fig. 2). The channel aquifer is bounded on each side 

by low, discontinuous, bedrock-cored ridges. The 

western ridge is breached by several small channels, 

and the eastern ridge is breached most notably at the 

Rt. 146 and I-87 interchange.

The aquifer is strongly confined (isolated from 

the atmosphere) by a thick, continuous lacustrine silt 

and clay unit (pl. 1A.2-3) over most of the central area 

of the Colonie Channel (fig. 2), as evidenced by strong 

ground-water-level responses to changes in 

atmospheric pressure (high barometric efficiency). The 

aquifer within the peripheral channel areas, or adjacent 

to them, is locally confined by till or lacustrine silt and 

clay or is unconfined, as indicated by weak groundwater-level responses to changes in atmospheric 

pressure (low barometric efficiency) or by the absence 

of a confining unit in well-log descriptions. These 
7

unconfined areas are much smaller than the confined 

areas but support the majority of high-yield wellfields. 

Most of these unconfined areas show no evidence of 

hydraulic connection with the deeper confined areas.

The Colonie Channel aquifer receives recharge 

from precipitation in localized areas where ice-contact 

deposits are unconfined (commonly overlain by 

lacustrine sand) or where fractured bedrock is at or 

near land surface. Both types of areas are indicated on 

fig. 2 and pl. 1A.3. Sporadic bedrock outcrops are 

present within the western half of town but are not 

identified in pl. 1A.3. 

The most productive areas of the channel 

aquifer are localized and can be as much as 85 ft 

thick. These permeable zones consist of ice-contact 

deposits (sand and gravel) that can provide shortterm yields up to about 600 gal/min (Dunn 

Geoscience Corporation, 1979) (pl. 1A.2-3). These 

zones can grade into impermeable silt- and claybound sand and gravel or till over short distances. 

The productive areas are most common in peripheral 

channel areas and are unconfined or locally confined 

(fig. 2, pl. 1A.2-3). They are tapped by six wellfields 

in the Town of Clifton Park (Boyack, Oakwood, 

Lapp, Roosevelt, Berry Farm, Meadows) and by two 

wellfields (Twin Lakes and Hoffman) in the Town of 

Halfmoon (pl. 1A.3). The Twin Lakes wellfield is 

outside the channel, just east of the bedrock ridge 

that bounds the eastern side of the channel. Its 

hydrogeologic setting is similar to that at the 

Oakwood wellfield, on the western side of the same 

bedrock ridge (pl. 1A.3).

Thick, confined, permeable deposits are present 

in the center of the channel only north of Rt. 146; this 

part of the aquifer is tapped by the Plank, Kinns, and 

Pierce wellfields. South of Rt. 146, the central part of 

the channel beneath the lacustrine silt and clay is 

predominantly silt- or clay-bound ice-contact deposits 

or poorly permeable till with some zones of thin, 

permeable ice-contact deposits. The only publicsupply well in this area is the Moe production well 

(Sa-1347). Aquifer tests at most wellfields that tap 

deep, confined channel areas (except Moe) show 

hydraulic evidence of localized areas of thick aquifer 

material. An aquifer test at the Moe well indicated a 

source of recharge beyond the immediate aquifer area 

(Dunn Geoscience Corporation, 1984a).

Some areas within and adjacent to the Colonie 

Channel lack thick, permeable ice-contact sand and 

gravel but contain many wells that tap fractured 

bedrock or thin shale gravel over bedrock (pl. 1A.2-3). 

Three of the town's wellfields (Linden, Calico Colony, 

and Park Lane) tap this channel-aquifer setting; the 

Linden well (Sa-1328) obtains sustained yields as high 

as 80 to 100 gal/min. These fractured-bedrock and 

shale-gravel aquifer settings typically are in hydraulic 

connection with adjacent ice-contact (or lacustrine 

sand) deposits and may provide a hydraulic 

connection among otherwise isolated ice-contact 

deposits in the Colonie Channel.

Till, which is grouped with poorly permeable icecontact deposits in pl. 1A.2-3, is the predominant 

confining unit in areas of bedrock highs, such as in 

much of the western half of Clifton Park and locally 

along the eastern and western edges of the Colonie 

Channel aquifer (pl. 1A.2-3). Till may be a less 

effective confining unit than lacustrine silt and clay in 

some areas, in that (1) some recharge appears to reach 

the underlying bedrock or ice-contact deposits, and 

(2) till typically is thinner and less continuous than 

lacustrine silt and clay and may have local permeable 

zones of sorted material or fractures, or it may be 

associated with ice-contact deposits that act as 

“windows” of higher permeability for recharge. 

Several wells completed in till or poorly permeable 

ice-contact deposits show water-level responses or 

water quality characteristic of unconfined or locally 

confined conditions.

The least productive wells in the study area 

typically are associated with high areas on the bedrock 

surface, particularly where overlain by thick till in the 

western half of town and along the bedrock ridge on 

the eastern side of the Colonie Channel. Wells 

completed at or within shallow bedrock in these areas 

typically yield 5 to 10 gal/min or less.

Alluvial Aquifer

Clifton Park recently has developed a groundwater supply from an alluvial aquifer within the flood 

plain of the Mohawk River at the southern edge of the 

town (pl. 1A.1). This aquifer has been referred to as 

the “Vischers Ferry aquifer” (C.T. Male Associates, 

P.C., 1996, 1999). Alluvial aquifers can be productive, 

reliable sources of water, especially if they are in 

hydraulic connection with an adjacent stream or river 

(Winslow and others, 1965). Water withdrawals from 

such aquifers can: (1) intercept natural ground-water 

flow that would otherwise discharge to the river, and 

(2) possibly induce river water to infiltrate and flow to 

Hydrogeologic Framework
8 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York

the well. This aquifer is typically about 25 ft thick, 

consists of sediments ranging from fine sand to coarse 

gravel and cobbles, and is commonly overlain by 5 to 

10 ft of recent alluvium (clayey or sandy silt) (C.T. 

Male Associates, P.C., 1996). The aquifer is 

considered unconfined in general because the finegrained alluvium is absent in some areas and because 

the observed similarity between river stage and 

ground-water levels near the river suggests hydraulic 

connection with the Mohawk River.

Four production wells that were installed in this 

aquifer during the middle to late 1990's yield 450, 600, 

800, and 1,125 gal/min (C. T. Male Associates, P.C., 

1998, 1999). Water pumped from the Vischers Ferry 

Preserve wellfield (pl. 1A.1) requires treatment for 

removal of manganese and sometimes iron. 

Concentrations of these constituents have increased in 

all production wells since the initial water samples 

were collected and analyzed. One of the wells is no 

longer used because the concentration of manganese 

in the water (about 7 mg/L) was too high to be 

adequately lowered during treatment (D. Connor, 

CPWA, oral commun., 1999).

CHEMICAL COMPOSITION OF 

GROUND WATER

The chemical composition of ground water in the 

Clifton Park area varies widely as a result of (1) the 

natural chemical evolution of ground water with time 

in the flow system, and (2) human activities that affect 

water quality, such as road-salt application and 

ground-water withdrawals. Classification of ground 

water into water types on the basis of major-ion 

composition (fig. 3) and selected other characteristics 

provides a framework for interpretation of groundwater flow and ground-water quality in the Clifton 

Park area.

Sixty ground-water samples were collected for 

chemical analysis during the study. All samples were 

analyzed in the field for pH, temperature, specific 

conductance, and dissolved oxygen concentration. 

Thirty-eight of the samples were analyzed for major 

ions, nutrients, and selected trace elements; 24 of 

these were collected by USGS personnel and 

analyzed by the USGS National Water Quality 

Laboratory in Arvada, Colo., and the remaining 14 

were collected with CPWA personnel and sent to the 

New York State Department of Health (NYSDOH) 

Laboratory and a commercial laboratory. A subset of 

12 samples was analyzed for tritium (3H) at the USGS 

tritium laboratory in Menlo Park, Calif., and 22 other 

samples were analyzed by CPWA for sulfate 

concentration only.

An additional 56 ground-water analyses were 

compiled from the USGS National Water-Quality 

Assessment (NAWQA) program, public water-supply 

sample analyses on file at the NYSDOH, and watersupply reports from private consultants. Except for the 

NAWQA samples, most of these 56 samples have 

incomplete records of major ions and field 

parameters; however, many of these samples can be 

assigned to one or more of the chemical water types 

described below.

Three naturally occurring types of water, and 

three human-affected types that occur within the 

channel aquifer are defined below and mapped on 

plate 1B.1-2. The naturally occurring water types 

range from relatively young (post-1952) water initially 

derived from recharge in local unconfined settings to 

pre-1952 water of unknown source in deeper, strongly 

confined settings. The human-affected types represent 

relatively young ground water that has been affected 

by ground-water withdrawals or by leachate from 

road-salt application and storage or from landfills.

Natural ground-water evolution is controlled by 

several processes, including mineral weathering (such 

as dissolution of calcite or iron sulfide minerals), ion 

exchange on aquifer material, and microbially 

mediated oxidation-reduction (redox) reactions. 

Microbial decomposition of organic matter within the 

aquifer results in progressively more reducing 

conditions along ground-water flow paths as 

dissolved oxygen, nitrate, manganese (IV), iron (III), 

sulfate, and carbon dioxide are sequentially reduced 

as they are utilized as electron acceptors in the 

decomposition process.

Calcium-Magnesium-Bicarbonate 

Water Type

The calcium-magnesium-bicarbonate 

(Ca-Mg-HCO3) water type (and related humanaffected water types described below) is predominant 

in the lacustrine sand aquifer, the alluvial aquifer, and 

the unconfined areas of the Colonie Channel aquifer 

(pl. 1B.2). Ca-Mg-HCO3 waters indicate shorter 

residence times within the ground-water-flow system 

than most other types described here. Most water 

samples from areas of residential development show 
9

100 80

SULFATE + CHLORIDE

CARBONATE + BICARBONATE

MAGNESIUM

PERCENT

CALCIUM + MAGNESIUM

SULFATE

PERCENT

SODIUM

CALCIUM CHLORIDE

ANIONS

PERCENT OF TOTAL

MILLIEQUIVALENTS PER LITER

CATIONS

60 40 20 0 0 20

20

0

40

60

80

100

40 60 80 100

20

0

40

60

80

100

20

20

20

0

0 0

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20

0

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40

40

40

40

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60

60

60

60

80

80

80

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80

80

100

80

100

100

Sodium-Bicarbonate

Sodium-Calcium-Bicarbonate

Calcium-Bicarbonate-Sulfate (SO4≥70 mg/l)

CHEMICAL COMPOSITION OF GROUND WATER

EXPLANATION

Calcium-Magnesium-Bicarbonate

Calcium-Sodium-Bicarbonate-Chloride

 (Cl=50 to 99 mg/l)

Sodium-Calcium-Bicarbonate-Chloride

 (Cl≥100 mg/l)

Figure 3. Six chemical ground-water types identified from complete major-ion analyses, Clifton Park area, 

New York, 1993-98.

Chemical Composition of Ground Water
10 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York

minor effects of contamination from road-salt 

application or storage (chloride concentrations 

between 10 and 49 mg/L), which indicate a relatively 

recent origin (post-development) for at least part of the 

water sample. Ca-Mg-HCO3 waters in confined areas 

of the channel aquifer indicate recharge from shallow, 

unconfined peripheral areas of the channel aquifer and 

(or) from the lacustrine sand aquifer in favorable 

settings along the edges of the channel. 

Ca-Mg-HCO3 waters have the widest pH range 

(6.1 - 8.2) of any water type discussed here. Low pH 

values (6.1 - 6.8) are characteristic of the shallowest 

ground waters (near the water table) and represent 

recent infiltration of acidic, oxygenated recharge 

waters through the unsaturated zone to the upper part 

of the unconfined aquifer, where calcite is absent or 

has been largely removed by weathering. Higher pH 

values (6.8 to 7.6) are most common in unconfined 

ice-contact deposits (channel aquifer), and also 

beyond leached zones in the lacustrine sand aquifer, 

where calcite is present and can undergo some 

dissolution, raising the pH and increasing 

concentrations of calcium, magnesium, and alkalinity. 

The longer the residence time of water in contact with 

calcite-bearing aquifer material under unconfined 

conditions, the more calcite dissolution will take 

place, and the harder the waters will become. Most 

Ca-Mg-HCO3 waters are moderately hard to hard 

(Hem, 1985, p. 159). As these waters enter confined 

areas of the channel aquifer and become isolated from 

the atmosphere, pH values may rise to as high as 8.2.

Calcium-Sodium-Bicarbonate-Chloride Water Type

The calcium-sodium-bicarbonate-chloride 

(Ca-Na-HCO3-Cl) water type represents 

Ca-Mg-HCO3 water that has been moderately affected 

by road-salt leachate and is defined by chloride 

concentrations of 50 to 99 mg/L. This type of water 

was found in the lacustrine sand aquifer in shallow 

observation wells near roads, and at supply wells in 

peripheral channel areas. Supply wells draw water 

from a large area, compared to an observation well; 

therefore, this water type from a supply well is a 

composite sample that reflects road-salt application 

over a wide area. These waters range from hard to very 

hard. Calcium concentrations are potentially increased 

by the exchange of sodium ions for sorbed calcium 

ions at exchange sites on clay minerals.

Sodium-Calcium-Bicarbonate-Chloride Water Type

The sodium-calcium-bicarbonate-chloride 

(Na-Ca-HCO3-Cl) water type represents 

Ca-Mg-HCO3 water that has been strongly affected by 

road-salt or landfill leachate, and is defined by chloride 

concentrations equal to or greater than 100 mg/L. 

Sodium typically is the dominant cation where roadsalt contamination is present, although all calcium 

concentrations in this water type exceed 50 mg/L. 

Calcium is the dominant cation (and magnesium is 

secondary) in two landfill-monitoring wells. This type 

of water ranges from hard to very hard. Chloride 

concentrations of this water, where it is affected by 

road salt, typically range from 100 to 260 mg/L but 

can exceed 500 mg/L in areas associated with point 

sources such as road-salt stockpiles and landfills.

Most occurrences of this water type are samples 

from a single well or a group of wells within small 

areas (pl. 1B.1); therefore, the actual distribution of 

this water type may be much more extensive within 

the lacustrine sand aquifer and channel aquifer than 

the limited data indicate. The presence of this water 

type at the Oakwood supply well (pl. 1B.1), which 

taps ice-contact deposits in the channel aquifer, 

suggests high chloride concentrations in areas of the 

lacustrine sand aquifer that contribute recharge water 

to that part of the channel aquifer. 

The extent of this ground-water type near the 

town's road-salt-storage facility and the town landfill 

(John M. McDonald Engineering, P.C., 1998), which 

is closed, is unknown beyond wells in the immediate 

vicinity of the sites. The potential is high for 

movement of ground water with elevated chloride 

concentrations to areas beyond these two sites. 

Calcium-Bicarbonate-Sulfate Water Type

The calcium-bicarbonate-sulfate 

(Ca-HCO3-SO4) water type, with SO4 > 70 mg/L 

and Ca > 100 mg/L, represents Ca-Mg-HCO3 water 

that has been affected by ground-water withdrawals at 

wellfields that tap unconfined or locally confined areas 

of the channel aquifer (pl. 1B.1). Pumping has altered 

the direction of local ground-water flow from predevelopment conditions, resulting in water-rock 

interactions that have affected ground-water 

composition. High hardness and high iron 

concentrations are the primary water-quality 

concerns with this water type, although elevated 

sulfate concentrations are also a concern in some 

areas. Magnesium concentration is elevated in 
11

some samples, but is always lower than that of 

calcium. Chloride concentrations typically are 

between 50 and 100 mg/L, presumably as a result 

of road-salt application. 

Initial water analyses (Dunn Geoscience 

Corporation, 1987A) from wells that currently 

produce the Ca-HCO3-SO4 water type indicate that the 

first water withdrawn from these sites typically was 

the Ca-Mg-HCO3 type described earlier. The regular 

withdrawal of ground water at these sites causes a 

stress to which the local flow system gradually adjusts; 

specifically, shallow, oxygenated Ca-Mg-HCO3 waters 

may be drawn downward into an initially anoxic icecontact deposit or fractured-bedrock environment that 

contains variable amounts of iron-sulfide minerals 

such as pyrite and marcasite (FeS2). The iron-sulfide 

minerals can be dissolved (oxidized) in the presence of 

oxygenated water. Oxidation of FeS2 yields dissolved 

iron, sulfate, and hydrogen ions. The release of 

hydrogen ions lowers the pH and results in further 

dissolution of calcite in the aquifer material. This 

process was suggested for some wells in the Clifton 

Park area by Bator (1997) and is described in Drever 

(1988). The resulting ground water type is defined by 

calcium concentrations greater than or equal to 100 

mg/L and sulfate concentrations greater than or equal 

to 70 mg/L and is classified as very hard. Hydrogen 

sulfide is common in this water type, suggesting that 

mixing with deeper reducing ground water from 

bedrock has resulted in some reduction of sulfate, or 

that the ground water in the bedrock initially contained 

hydrogen sulfide.

The most extreme examples of this water type are 

at the Lapp (Sa-1380) and Roosevelt (Sa-1282) 

wellfields (pl. 1B.1), both of which tap the same 

deposit of unconfined ice-contact material along the 

eastern side of the channel aquifer. Aquifer tests at 

these wellfields indicated a limited and apparently 

isolated local aquifer area and resulted in the 

dewatering of several local domestic wells that are 

completed in relatively thin unconsolidated deposits or 

in bedrock (Dunn Geoscience Corporation, 1987). 

Dewatering of part of an aquifer area that contributes 

to a wellfield suggests a strong possibility of 

interaction between shallow, recently recharged 

ground water and the upper (fractured) bedrock 

environment; this would result in more intense 

oxidation of FeS2 and more dissolution of carbonate 

minerals here than in other similar wellfield 

environments within the study area that have not 

undergone as much stress from water withdrawals.

Sodium-Calcium-Bicarbonate Water Type

The sodium-calcium-bicarbonate (Na-Ca-HCO3) 

water type represents an intermediate step in the 

natural evolution of Ca-Mg-HCO3 water toward NaHCO3 water, or the mixing of Ca-Mg-HCO3 water 

with Na-HCO3 water at supply wells in confined 

settings. Sodium concentrations generally equal or 

exceed those of calcium; the increase in sodium results 

from cation exchange for calcium at exchange sites on 

aquifer materials. The residence time of this water 

probably is intermediate between that of relatively 

young Ca-Mg-HCO3 water and that of the relatively 

older Na-HCO3 water. Na-Ca-HCO3 water is typically 

present in confined or locally confined settings along 

the edges and in peripheral areas of the Colonie 

Channel aquifer (pl. 1B.1), where ground-water 

withdrawals stress the aquifer and alter flow 

directions. This intermediate residence-time water 

type within deep, confined areas of the Colonie 

Channel indicates recharge from the lacustrine sand 

aquifer and (or) from unconfined areas of the channel 

aquifer. Areas that contain this water type include: 

(1) the channel area immediately east of the Clifton 

Park Landfill (Sa-1229), (2) the eastern side of the 

channel (Sa-1500) north of the Moe supply well 

(Sa-1347) through the Linden (Sa-1328) and Clifton 

Park Center (south) supply and irrigation wells 

(Sa-1456, Sa-1308), and (3) the channel area centered 

around the Plank (Sa-1450) and Kinns (Sa-1197) 

supply wells (pl. 1B.1).

The longer residence time of this intermediate 

water type than of Ca-Mg-HCO3 water results in 

distinct chemical differences. As water flows from 

recharge areas to confined areas, isolation from 

atmospheric carbon dioxide allows pH to 

progressively increase. Waters with pH values of 7.5 to 

7.9 are not far removed from recharge areas, whereas 

those with pH of 8 to 8.8 indicate progressively more 

time within the confined areas of the channel aquifer. 

Waters of this type also are more reduced than the 

Ca-Mg-HCO3 waters — dissolved oxygen and nitrate 

generally are absent, and reduced iron (II) is typically 

found in low concentrations (less than 0.3 mg/L), but 

exceeds 1 mg/L in a few samples. Sulfate 

concentrations exceed 30 mg/L in relatively young 

Na-Ca-HCO3 waters but are less than 5 mg/L in 

Chemical Composition of Ground Water
12 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York DEPTH TO WATER, IN FEET BELOW LAND SURFACE

MAR APR MAY JUNE JUL AUG SEP OCT NOV DEC JAN FEB

1998

0

1

2

3

4

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6

7

8

1997

deeper (presumably older), more confined settings. 

Hydrogen sulfide and (or) methane may be present. 

Chloride concentrations are generally less than 

50 mg/L and may be as low as 4 mg/L.

Sodium-Bicarbonate Water Type

The sodium-bicarbonate (Na-HCO3) water type is 

the oldest (has the longest residence time) of any type 

within the channel aquifer. These waters are limited to 

the deep, most confined areas within the center of the 

Colonie Channel (pl. 1B.1) and show little or no effect 

from human activity. Tritium-based ages of selected 

water samples are pre-1952, which predates most 

residential development in the area. Sodium 

(72 to 129 mg/L) is the dominant cation in this type of 

water, and calcium concentrations are low 

(1 to 8 mg/L); thus, the water is soft. Sulfate 

concentrations also are low (< 5 mg/L), presumably as a 

result of microbial reduction, and pH can be extremely 

high (from 8.2 to 9.4). Iron concentrations generally are 

low and methane is common. Fluoride concentrations 

are high (1.3 to 2.2 mg/L) in the deepest areas that have 

been least disturbed by pumpage stresses (pH >9, 

calcium <3 mg/L). Chloride concentrations range from 

3 to 57 mg/L. The low chloride values indicate the 

absence of road salt in pre-development recharge; the 

higher values probably represent mixing with deeper 

ground water in the bedrock.

GROUND-WATER LEVELS

Water levels in observation wells provide 

information on aquifer responses to natural climatic 

conditions and to short- and long-term ground-water 

withdrawals, especially within the channel aquifer. 

Sources of water-level data include (1) drillers’ logs, 

(2) aquifer tests conducted by private consultants, 

(3) a USGS-CPWA well network that ranged from 30 

to 40 wells in which water levels were measured 

during 1995-98, and (4) 68 wells in the eastern half of 

town in which water levels were measured by USGS 

during August and September 1998. 

Unconfined Conditions

The typical annual cycle of water-level 

fluctuations (fig. 4) is largely controlled by seasonal 

variations in evapotranspiration (ET). During the 

growing season (late spring to early fall), vegetation 

intercepts most precipitation that enters the soil and 

thereby largely prevents recharge; shallow ground 

water can also be lost through ET. This loss results in a 

seasonal water-level decline as ground water continues 

to discharge to streams, lakes, and wetlands. Under 

drought conditions, discharge areas such as wetlands 

and small streams may dry up. During the late fall, ET 

decreases as vegetation dies off; this allows infiltrating 

precipitation to recharge the unconfined aquifer areas 

and raise water levels. Winter recharge is limited by 

frozen ground and snow accumulation, and water 

levels tend to gradually decline. In early spring, as the 

ground thaws and snow melts, ET is minor and 

recharge resumes, typically raising water levels to 

their highest point of the year.

Confined Conditions

Natural short- and long- term water-level 

fluctuations in wells that tap confined aquifers differ 

from those that tap unconfined aquifer settings. Water 

levels in wells that tap confined parts of the channel 

aquifer may either show subdued seasonal fluctuations 

that lag behind those in unconfined areas, or they may 

show no discernible annual trend, depending on the 

degree of confinement and the amount of interference 

from ground-water pumping. Direct recharge from 

precipitation does not occur; instead, water levels 

respond to changes in barometric or atmospheric 

pressure (Todd, 1980). Barometric-pressure effects are 

greater in confined settings than in unconfined 

settings. An increase in barometric pressure forces 

water levels in wells downward; then, as the air 

pressure decreases, the water levels rise. The largest 

Figure 4. Ground-water levels in the lacustrine sand 

aquifer at USGS observation well Sa-1285, Clifton Park 

area, New York, March 1997 through February 1998 

(Location is shown on pl. 1A.1)
13

fluctuations due to barometric-pressure changes in the 

study area are about 1.5 ft; a 1-in change in barometric 

pressure, expressed in inches of mercury, is equivalent 

to a 1.13-ft change in water level in a well that taps a 

strongly confined area of the aquifer.

Barometric efficiency is a measure of the 

responsiveness of water levels in wells to changes in 

barometric pressure and is indicative of the degree of 

confinement of an aquifer area tapped by a well. A 

measured change in ground-water level at a given well 

divided by the corresponding barometric-pressure 

change (converted from inches of mercury to 

equivalent feet of water) is expressed as a percent 

value. The greater the effect of barometric-pressure 

changes on ground-water levels, the higher the 

efficiency, and the greater the confinement (distance 

or degree of hydraulic isolation from unconfined 

areas). A 100-percent barometric efficiency at a well 

suggests that the aquifer area it taps has no strong 

nearby hydraulic connection with recharge 

(unconfined) areas. Lower barometric efficiencies 

indicate some degree of hydraulic connection with 

unconfined settings. Wells that tap locally confined or 

unconfined settings have barometric efficiencies of 

less than 30 percent.

Wells that tap the confined central channel area of 

the Colonie Channel aquifer have barometric 

efficiencies of 60 to 100 percent. Two wells (Sa-1229, 

Sa-1500) west-northwest of the Moe supply well (pl. 

1A.3) have barometric efficiencies in the low end of 

this range, indicating a greater hydraulic connection 

with recharge areas here than in other central-channel 

areas. Barometric efficiencies of wells that tap some 

of the peripheral channel-aquifer areas were less than 

30 percent; this indicates local confinement or a lack 

of confinement.

Responses to Pumping Wells

Aquifer tests are required by the New York State 

Department of Environmental Conservation 

(NYSDEC) to assess sustainable yields for all new 

public-supply wells. Semi-log plots of water-level 

drawdown in an observation well (as a function of 

time since start of pumping) provide trend lines that 

give an indication of the continuity of the aquifer 

material and the potential for induced recharge. 

A straight-line plot indicates relatively uniform 

aquifer thickness and geometry within the aquifer 

area affected by the pumping. Straight timedrawdown lines were reported at the Roosevelt 

(Environmental Hydrogeology Corporation, 1989a), 

Lapp (Dunn Geoscience Corporation, 1987), Calico 

Colony (Dunn Geoscience Corporation, 1977), 

Boyack (G.M. Erickson, Johnson Division, written 

commun., 1973), and Kinns (Dunn Geoscience 

Corporation, 1978) wellfields.

A decrease (flattening) in the slope of this line 

(a decrease in drawdown rate per log cycle of time) 

during a test indicates a positive hydraulic boundary, 

such as an increase in aquifer permeability or 

thickness, or an additional source of recharge to the 

aquifer at some distance from the well. Aquifer tests 

indicated positive boundaries at the Moe (Dunn 

Geoscience Corporation, 1985a), Berry Farm 

(Sa-1339) (Environmental Hydrogeology Corporation, 

1990), Meadows (Sa-1342) (Environmental 

Hydrogeology Corporation, 1990), and Elnora (Dunn 

Geoscience Corporation, 1984b) wellfields and at an 

unused production well (Sa-1331) adjacent to the Park 

Lane wellfield (Environmental Hydrogeology 

Corporation, 1989b).

An increase (steepening) in the slope of the 

time-drawdown line suggests a negative hydraulic 

boundary, such as a decrease in aquifer permeability 

or thinning of the aquifer in one or more directions 

away from the supply well. Wells at which tests 

indicated negative hydraulic boundaries included the 

Plank (Dunn Geoscience Corporation, 1979) and 

Linden (C.T. Male Associates, P.C., 1989) wells, 

both of which tap confined settings within the 

Colonie Channel.

Water levels were measured weekly by USGS and 

CPWA during 1995-98 at a network of approximately 

35 wells that tap the channel aquifer. Some of these 

wells were monitored continuously by float-driven 

graphical recorders or pressure transducers coupled to 

electronic dataloggers for varying periods during the 

study. Comparison of water-level hydrographs with 

supply-well pumpage records can indicate whether or 

not there is hydraulic interconnection among wells. 

Wells in which water-level data indicate hydraulic 

interconnection with a pumping well are connected by 

dotted lines in pl. 1A.3.

Water Levels in the Colonie Channel 

Aquifer, August-September 1998

Ground-water levels in 68 wells completed in the 

Colonie Channel aquifer were measured or estimated 

Ground Water Levels
14 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York

during August-September 1998. Water levels in 

several inaccessible wells were estimated from 

measurements made within the previous 4 years. 

Water-level altitudes were calculated from known 

measuring-point altitudes or from estimated 

geographic-information-system (GIS) digitalelevation-model (DEM)-generated altitudes derived 

from a topographic map with a 10-ft contour interval. 

A water-level (potentiometric-surface and water-table) 

map was constructed from the data (pl. 1B.1); this map 

provides a “snapshot” (August -September 1998) of 

the potentiometric surface of the confined “central 

channel” and “peripheral channel” areas, and the 

water-table surface in the unconfined “peripheral 

channel” areas of the Colonie Channel aquifer.

Interpretation of August-September 1998 waterlevel data is facilitated through comparison of water 

levels measured in the most productive areas of the 

channel aquifer before and during development in the 

late 1960’s through the early 1970’s. Drillers’ logs and 

recollections (R. Ferraioli, Dick Ferraioli, Inc., oral 

commun., 1996) indicate water levels in 1972 were 

about 21 ft below land surface at the Boyack wellfield 

(supply well 3) in the southern part of town and, in 

1973, were at land surface at the Plank supply well; 

they also indicate flowing artesian conditions (water 

level 35 to 40 ft above land surface) in 1968 at the 

Kinns supply well in the northern end of town 

(pl. 1B.1). These water levels correspond to altitudes 

of about 240 to 255 ft above sea level. The several 

years over which these measurements were made (by 

unknown means), and the relatively small difference in 

water-level altitude among these areas suggest 

generally low hydraulic gradients within the Colonie 

Channel aquifer. Accurate delineation of predevelopment ground-water-flow directions and, thus, 

of recharge or discharge areas, is not possible from the 

data. If hydraulic gradients within the aquifer were 

low, flow into and through this aquifer probably was 

minor before public-supply withdrawals began in the 

early 1960’s.

The August-September 1998 potentiometric 

surface in the Colonie Channel aquifer (pl.1B.1) is 

much lower than its estimated pre-1960’s altitude of 

about 250 ft above sea level—within the confined 

central channel area, it is as much as 100 ft lower, and 

is as much as 190 ft below the current (1998) groundwater levels in unconfined peripheral channel areas. 

Water-level contours of 250 ft and lower are depicted 

as depression (hachured) contours on plate 1B.1 to 

show the effects of ground-water withdrawals on the 

system relative to pre-development conditions. A 

depressed potentiometric surface relative to predevelopment conditions is also evidenced by longterm water-level declines at several supply and 

observation wells completed in confined areas of the 

channel aquifer. This net lowering of water levels over 

time indicates that ground-water withdrawals from the 

confined areas of the channel aquifer have exceeded 

the rate of recharge.

The potentiometric surface within the channel 

aquifer is characterized by two large depressions north 

and south of a narrow east-west ground-water divide 

that spans the channel in the southern part of Clifton 

Park (pl. 1B.1). Ground water in deep, confined areas 

of the channel aquifer flows northward north of the 

divide and southward south of the divide. Water levels 

within the central channel area are highest at the 

divide, although these levels are at least 20 ft lower 

than in the pre-development period. The relatively 

high water levels at the divide suggest that the 

peripheral areas or the edges of the channel at this 

locale are a major source of recharge for the deep, 

confined channel aquifer. The large depressions in the 

potentiometric surface north and south of the divide 

indicate that ground-water withdrawals affect large 

areas within the central channel and that hydraulic 

continuity exists within each of these areas despite 

local variability in the type and thickness of aquifer 

material (pl. 1A.3). In contrast, the large water-level 

differences (steep gradients) and the chemical watertype differences between the unconfined or locally 

confined peripheral channel areas and the deep, 

confined central channel area indicate little or no 

hydraulic connection and, thus, a low potential for 

recharge along much of the channel. 

The northern depression in the potentiometric 

surface is the larger and deeper of the two and extends 

northward beyond the study area for an unknown 

distance toward or beyond Round Lake (pl. 1B.1). 

Ground-water levels in much of the northern 

depression are below 200 ft and are just below 150 ft 

in a small area around the Kinns supply well (pl. 

1B.1). The Plank and Kinns supply wells have been 

the major ground-water withdrawal points within the 

northern depression since the early 1970's. The 

potentiometric surface and the hydrogeologic settings 

north of the Kinns Supply well are variable and illdefined, but the earliest reported water levels in this 

area (flowing artesian) are about 100 ft higher than the 
15

level of Round Lake and therefore suggest a lack of 

hydraulic interconnection between the lake and the 

deep, confined aquifer. Water may enter the northern 

depression from deep channel-aquifer areas farther to 

the north, however. 

The southern depression extends an unknown 

distance southward from the divide to at least the 

Mohawk River flood plain. The depression is partly a 

result of ground-water withdrawals within the study 

area at the Boyack wellfield on the eastern side of the 

channel (pl. 1B.1). Other potential causes outside of 

the study area may include (1) the discharge of Colonie 

Channel aquifer water to the Mohawk River flood 

plain, where erosion has removed the upper parts of the 

confining units and perhaps created some degree of 

hydraulic interconnection between the channel aquifer 

and overlying flood-plain deposits, or (2) propagation 

of lowered ground-water levels beneath the river and 

northward into the Clifton Park area in response to 

withdrawals from supply wells that tap deep, confined 

areas of the Colonie Channel aquifer south of the 

Mohawk River in Albany County (fig. 1).

CONCEPTUAL MODEL OF GROUNDWATER FLOW WITHIN THE LACUSTRINE 

SAND AQUIFER AND COLONIE CHANNEL 

AQUIFER

The lacustrine sand and Colonie Channel 

aquifers differ significantly in their sources of 

recharge, directions of ground-water flow, and modes 

of discharge. The aquifers are hydraulically 

connected in places along the peripheral areas of the 

Colonie Channel. Ground-water flow is generally 

downward from the lacustrine sand aquifer to the 

Colonie Channel aquifer, where ground-water 

withdrawals are greatest.

Lacustrine-Sand Aquifer

Direct precipitation is the major source of 

recharge to the lacustrine sand aquifer (fig. 5). Runoff 

from precipitation that falls on till-covered hillsides 

adjacent to the channel area may also contribute 

recharge to this aquifer where water moving 

downslope infiltrates into the soil, rather than draining 

to a stream. Most recharge occurs during late fall, and 

during late winter and early spring (fig. 4) when 

evapotranspiration (ET) is minimal. Recharge does not 

occur in ground-water discharge areas such as streams, 

lakes, wetlands, springs, or seeps.

Two other sources of recharge are leakage from 

water mains and sewer lines and infiltration of lawnirrigation water. Historically, most of this water 

represents a net transfer from the channel aquifer to 

the lacustrine sand aquifer. Recharge is reduced in 

developed areas where precipitation falls on 

impervious (paved) areas and is diverted (lost) to local 

streams rather than stormwater retention basins, where 

infiltration and recharge can occur.

Depth to the water table in the lacustrine sand 

aquifer ranges from 0 to about 60 ft below land 

surface, depending on local relief and ground-water 

withdrawals. Streams, wetlands, and lakes generally 

represent the intersection of the water table with land 

surface. Periods of drought, such as in the late spring 

and early summer of 1997 (fig. 4), cause a marked 

lowering of water levels. For example, water levels in 

well Sa-1285 (pl. 1A.1) were less than 1 ft below land 

surface in the spring of 1997 but declined about 6.5 ft 

over the next 4 months. As ground-water levels decline 

during the summer, streams progressively decline in 

flow and dry up. 

Ground-water flow under natural, unconfined 

conditions generally parallels the local topography and 

is downgradient toward discharge areas such as 

streams, wetlands, and lakes (fig. 5). Within the study 

area, water in the lacustrine sand aquifer discharges 

mostly to Stony Creek, the Dwaas Kill, and other 

smaller drainages (fig. 1). Other discharges from the 

lacustrine sand aquifer include supply-well 

withdrawals that intercept ground water that would 

naturally discharge to surface water (fig. 5) and flow 

into underlying or adjacent channel-aquifer settings, 

where confining units are locally absent and hydraulic 

heads (water levels) are lower. 

The chemical composition of water from the 

lacustrine sand aquifer indicates shorter groundwater residence times and greater susceptibility to 

contamination from human activities at land surface 

than water in the deeper areas of the Colonie 

Channel aquifer.

Colonie Channel Aquifer

The part of the Colonie Channel aquifer that lies 

within the study area may receive local recharge from: 

(1) direct infiltration of precipitation in peripheral 

channel areas where surface exposures of ice-contact 

Conceptual Model of Ground-Water Flow within the Lacustrine Sand Aquifer and Colonie Channel Aquifer
16 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York
17

Peripheral Channel Areas

The peripheral channel areas (fig. 2) contain 

unconfined and confined settings that include the 

majority of high-yield wellfields in the study area. 

Unconfined settings (pl. 1A.3) include the recharge 

areas within the peripheral channel areas. Recharge 

occurs either directly at surface exposures of icecontact deposits or fractured bedrock, but more 

commonly through the overlying lacustrine sands. 

Unconfined areas are more extensive than 

depicted in pl. 1A.3; the limited subsurface data 

probably miss locally unconfined “windows” of 

permeable sediments within otherwise till-covered 

areas of low permeability along the channel edges.

Water levels and ground-water types in peripheral 

channel areas resemble those in the lacustrine sand 

aquifer more than they resemble those in the central 

channel area. Water ranges from the Na-Ca-HCO3

type in some confined areas where residence times are 

relatively long, or least affected by ground-water 

withdrawals, to the Ca-Mg-HCO3 type along with 

subtypes affected by road salt and pumpage in areas 

where water-residence times are relatively short 

(especially where pumping wells induce ground-water 

flow at higher than natural rates). Areas with relatively 

young ground water are either unconfined or in 

hydraulic connection with unconfined areas. Examples 

of confined peripheral channel areas that appear to 

derive water from local recharge on the eastern side of 

the channel include (1) the area from the Rt. 146 and 

I-87 intersection southward to the area west of the 

Roosevelt supply well, and (2) the area immediately 

east of the Moe supply well southward to at least the 

Oakwood supply well (pl. 1B.1). Examples on the 

western side of the channel are (1) immediately west 

of the Stony Creek Reservoir, including the landfill 

site, and (2) the area just west of the landfill within a 

shallow side channel that trends northward and is 

tapped by the Berry Farm (Sa-1339), Meadows 

(Sa-1342, 1343), Park Lane (Sa-1222, 1223, 1224), 

and Calico Colony (Sa-1167, 1168) wellfields

 (pl. 1A.3, 1B.1).

Central Channel Area

The central channel area (fig. 2) contains the 

deepest and most strongly confined parts of the 

Colonie Channel aquifer. Large declines in groundwater levels over short distances between peripheral 

channel areas and the central channel area are 

indicative of little or no hydraulic interconnection. 

This is characteristic of much of the Colonie Channel 

segment in the Clifton Park area (eastern side of 

section A-A ́, pl. 1B.1-2, fig. 5). The most isolated 

aquifer areas (those not tapped by public-supply wells) 

are characterized by soft, Na-HCO3 waters with high 

pH and elevated fluoride concentrations.

Two zones within the central channel area show 

evidence of recharge from peripheral channel areas. 

The first is in the southern half of the channel, 

immediately south of Englemore Road, as indicated 

by water-level and water-chemistry data (pl. 1B.1). 

This zone is apparently recharged by water from 

peripheral areas on both sides of the channel. Waterlevel and water-chemistry data suggest that recharge 

on the eastern side of the channel is not derived from 

the Lapp wellfield area, but rather from areas slightly 

to the north (near Grooms Rd.) and south (near the 

Moe supply well) (pl. 1B.1). Recharge from the 

western side of the channel appears to be derived from 

an area that contains the closed town landfill.

The second central-aquifer zone that appears to 

receive recharge from the peripheral channel areas is 

in the northern end of town; water from this zone 

indicates recharge induced by pumping at the Plank 

and Kinns supply wells. The decline of water levels in 

this area from 1973-1998 (fig. 6) has resulted in the 

lowest ground-water levels in the study area. This 

decline and the absence of definitive ground-water 

mounding on the potentiometric-surface map, suggest 

that this zone has a weaker hydraulic connection with 

recharge areas than does the southern zone. Results of 

ground-water-age dating with tritium indicate that 

most Kinns well water entered the aquifer system 

before 1952 and that water from the Plank well is a 

mixture of pre- and post-1952 waters. Two possible 

nearby recharge areas are identified on plate 1A.3. 

The first recharge area is in the Country Knolls 

West area along Greensboro Boulevard (indicated in 

pl. 1A.3 as a local unconfined area, and in pl. 1B.1 as 

an area of Ca-Na-HCO3-Cl water). The lacustrine sand 

aquifer directly overlies a permeable zone of the 

peripheral channel area (pl. 1A.3) at this site. A deep 

ground-water level in 1998 (W. Schlesier, CPWA, oral 

commun., 1998) at a well (Sa-1464) screened in the 

permeable zone indicates that the overlying lacustrine 

sand is unsaturated. Use of shallow domestic well 

points in other parts of this residential area suggests 

that water in the lacustrine sand aquifer locally drains 

through this recharge “window” to the peripheral 

channel aquifer area below. The deep ground-water 

Conceptual Model of Ground-Water Flow within the Lacustrine Sand Aquifer and Colonie Channel Aquifer
18 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York

No data

available

Sa-1100 (USGS Observation well)

Nearby unnamed observation well

manual

measurements recorder

measurements

(15-minute) manual

measurements

0

20

40

60

80

100

120

1970 1975 1980 1985 1990 1995 2000

1975

WATER LEVEL, IN FEET

BELOW MEASURING POINT

PUMPAGE, IN MILLION

GALLONS PER YEAR

1970 1980 1985 1990 1995 2000

200

180

160

140

120

100

80

60

40

20

0

level at well Sa-1464 is consistent with what is 

expected in that area of the central channel and, 

therefore, suggests a hydraulic pathway for recharge. 

The second potential recharge area (about 0.5 to 

1 mi south of Round Lake) is indicated by a till 

confining unit underlain by a bedrock high within the 

channel (pl. 1A.3) and by Ca-Na-HCO3-Cl water 

immediately south of Round Lake on plate 1B.1. This 

area is included as a potential recharge area on the 

basis of its hydrogeologic setting (only one water 

analysis was performed, and no water-level data from 

this area were available). A bedrock high (north-south 

ridge?) within the channel was penetrated during the 

drilling of several wells in this area; the bedrock at one 

site is overlain by only 25 ft of till. Hydraulic 

connection with the underlying central channel area is 

uncertain, but the possibility is noted because of 

proximity to the Kinns and Plank wells. A water 

sample (Ca-Na-HCO3-Cl type) from well Sa-1441, 

immediately north of this area (pl. 1B.1), indicates 

relatively young water beneath 69 ft of confining unit 

(till and lacustrine silt and clay).

Most ground-water discharge from the central 

channel area is through withdrawals at supply wells in 

Clifton Park proper, although some discharge might 

also occur to the Mohawk River floodplain and 

Figure 6. Water-level trends and annual pumpage for 1973-1999 at the Plank wellfield, Clifton Park, New York.
19

perhaps to supply wells tapping central channel areas 

south of the Mohawk River. Minor discharge to 

streams or wetlands may occur in unconfined aquifer 

areas where pumping has not affected water levels. 

Pumping from the Colonie Channel aquifer since the 

1960’s has resulted in large, long-term water-level 

declines that indicate withdrawal rates have exceeded 

recharge rates (fig. 6). Recovery of water levels in the 

central channel area can be achieved only by reducing 

net ground-water withdrawals within the affected 

channel segments (north and south of the groundwater-flow divide). The beneficial effect of reduced 

pumpage on water levels is evident at the Plank 

wellfield; the reduction in 1998-99 pumpage and 

resultant rise of ground-water levels (fig. 6) started in 

mid-1998, when a new wellfield in the alluvial aquifer 

went online.

SUMMARY

Clifton Park's water supply is derived from three 

aquifers—a lacustrine sand aquifer, the Colonie 

Channel aquifer, and an alluvial aquifer. All are within 

the eastern half of the study area. The lacustrine sand 

aquifer is unconfined and is thickest over the Colonie 

Channel, a north-south-trending bedrock channel that 

has been buried by glacial deposits. The aquifer is 

most productive on the eastern side of the channel, 

where medium to coarse lacustrine deltaic sand and 

gravel are locally present. The fine-grained texture of 

the lacustrine sand throughout most of the aquifer 

interferes with pump operation and therefore limits 

water use.

Most supply wells in the area are completed in the 

Colonie Channel aquifer, which consists of permeable 

ice-contact sand and gravel and the fractured top of 

bedrock, which is predominantly shale. Fractured 

bedrock is a potential aquifer throughout the area, but 

the highest well yields are associated primarily with 

ice-contact deposits in the Colonie Channel aquifer. 

The aquifer is confined by lacustrine silt and clay 

throughout most of the channel; the degree of 

confinement is greatest over the central part of the 

channel. Peripheral areas of the channel range from 

confined to unconfined. Confining units in these areas 

include till, impermeable ice-contact deposits, or thin 

lacustrine silts and clays.

The alluvial aquifer along the Mohawk River at 

the southern end of the study area has been tapped 

only since 1998. It consists of fluvial sand and gravel 

about 25 ft thick that is locally confined by about 10 

ft of fine-grained alluvium. This aquifer has the 

highest sustainable yields of the three aquifers 

because pumping wells are probably inducing 

recharge from the Mohawk River and (or) from 

nearby ponds and wetlands. 

Chemical analyses of ground-water samples from 

the Colonie Channel and lacustrine sand aquifers were 

grouped into six ground-water types that provide a 

general indication of the relative residence time of 

water within the aquifers. The shortest ground-waterresidence times are associated with calciummagnesium-bicarbonate waters and three other related 

waters—two affected by human activities, such as 

application of road salt, and one affected by groundwater flow path changes associated with ground-water 

withdrawals. These waters are most common in the 

lacustrine sand aquifer or unconfined areas of the 

channel aquifer. The presence of these waters within 

confined peripheral channel areas indicates that 

pumping has induced recharge through local 

“windows” (areas where confining units are absent) in 

some of the till-dominated areas. Sodium-calciumbicarbonate water evolves from calcium-magnesiumbicarbonate water (or mixing) and, thus, may imply 

increased ground-water residence times; this water 

type was present in parts of the aquifer channel 

confined by till as well as in deep central channel areas 

where ground-water withdrawals have induced 

recharge from peripheral channel areas. The oldest 

ground water is the sodium-bicarbonate type, which 

represents natural (pre-development) conditions; it is 

present only within the most confined central channel 

areas, far from supply wells.

Water-level data from aquifer tests and from a 

monitoring-well network indicate hydraulic 

interconnection among wells finished in the channel 

aquifer, which includes ice-contact deposits and 

shallow fractured bedrock. A potentiometric-surface 

map based on a 2-month survey (1998) of water levels 

in the channel aquifer indicated two large water-level 

depressions within the strongly confined central 

channel area. These areas are separated by a groundwater-flow divide, which suggests recharge is coming 

from peripheral channel areas, one of which may 

include Clifton Park’s closed landfill. Comparison of 

pre- or early-development water-level data with water 

levels measured in 1998 indicate that water levels have 

declined significantly in the central channel area of the 

Summary
20 Ground-Water Resources of the Clifton Park Area, Saratoga County, New York

aquifer—an indication that, over time, withdrawals 

have exceeded recharge rates.

A conceptual model of the lacustrine sand and 

channel aquifers indicates that recharge from 

precipitation occurs across most of the lacustrine sand 

aquifer and in limited unconfined or semiconfined 

areas of the channel aquifer. Most recharge that enters 

the lacustrine sand aquifer flows through the aquifer 

and discharges to streams and lakes. Recharge enters 

confined peripheral channel areas through adjacent 

unconfined areas. Peripheral channel areas, in turn, 

provide limited recharge to the central channel area 

through “windows” of hydraulic interconnection. The 

central channel area also may receive lateral recharge 

from channel segments north or south of the Clifton 

Park area. Discharge from the confined areas of the 

channel aquifer occurs through ground-water 

withdrawals at supply wells and possibly as flow 

beyond the study-area boundaries.

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