Prepared in cooperation with 

CITY OF NEWTON, IOWA

Ground Water Near Newton,

Jasper County, Iowa

Water-Resources Investigations Report 01 4148

U.S. Department of the Interior 

U.S. Geological Survey

U.S, Department of the Interior 

U.S. Geological Survey

Ground Water Near Newton, 

Jasper County, Iowa

By ROBERT C. BUCHMILLER 

Water-Resources Investigations Report 01-4148

Prepared in cooperation with the 

CITY OF NEWTON, IOWA

Iowa City, Iowa 

2001
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement 

by the U.S. Government.

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

District Chief U.S. Geological Survey

U.S. Geological Survey Information Services

P.O. Box 1230 Building 810

400 S. Clinton St., Rm. 269 Box 25286, Federal Center

Iowa City, IA 52244-1230 Denver, CO 80225-0286
CONTENTS

Abstract.........................................................................................................................................................^ 1

Introduction..............................................................................._ 1

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

Previous Investigations................................................................................................................................................ 2

Description of Study Area........................................................................................................................................... 5

Acknowledgments....................................................................................................................................................... 5

Description of South Skunk River Alluvial Deposits Near Newton ..................................................................................... 5

Collection of Seismic-Refraction and Observation-Well Data.................................................................................... 5

Thickness andLithology ............................................................................................................................................. 9

Ground-Water Flow..................................................................................................................................................... 9

Water Quality.......................................................................................................................................^ 17

Ground-Water Sources in the Jasper County Area................................................................................................................ 25

Alluvial Aquifers....................................................................^ 25

Glacial-Drift And Buried-Channel Aquifers............................................................................................................... 26

Bedrock Aquifers.................................................................... 26

Summary................................................................................................................................................................................ 27

References............................................................................................................................................................................. 28

FIGURES

1. Maps showing location of Jasper County and Newton study area in Iowa............................................................. 3

2. Map showing location of data-collection sites in South Skunk River Valley near Newton, Iowa.......................... 4

3. Geologic sections A-A' through L-L based on seismic-refraction and test-hole data............................................ 8

4-6. Maps showing:

4. Altitude and configuration of bedrock surface based on seismic-refraction and test-hole data, South

Skunk River Valley near Newton, Iowa............................................................................................................. 18

5. Thickness of unconsolidated deposits based on seismic-refraction and test-hole data, South Skunk

River Valley near Newton, Iowa........................................................................................................................ 19

6. Potentiometric surface of alluvial aquifer, South Skunk River Valley near Newton, Iowa, June 6, 2000......... 21

TABLES

1. Description of hydrogeologic units in central Iowa................................................................................................ 6

2. Description of drilled test holes and geologic information..................................................................................... 10

3. Static water-level measurements from observation wells, municipal wells, and surface-water sites in the

South Skunk River alluvium near Newton, Iowa, February, June, and October 2000............................................ 20

4. Selected water-quality characteristics and constituents in water from selected wells in the South Skunk River

alluvial aquifer near Newton, Iowa, 2000............................................................................................................... 22

Contents
CONVERSION FACTORS, ABBREVIATIONS, AND VERTICAL DATUM

Multiply By

Length

inch (in.) 2.54

foot (ft) 0.3048

mile (mi) 1.609

Area

acre 4,047

square mile (mi2) 2.590

Volume

cubic foot (ft3) 28.32

gallon (gal) 3.785

million gallons (Mgal) 3,785

Flow

cubic foot per second (ft3/s) 0.02832

foot per second (ft/s) 0.3048

gallon per minute (gal/min) 0.06308

million gallons per day (Mgal/d) 3,785

To obtain

centimeter

meter

kilometer

square meter

square kilometer

liter

liter

cubic meter

cubic meter per second

meter per second

liter per second

cubic meter per day

Abbreviated water-quality units used in this report: Chemical concentrations are 

reported in milligrams per liter (mg/L) and micrograms per liter (ug/L). A milligram 

per liter expresses the concentration of chemical constituents in solution as weight 

(milligrams) of solute per unit volume (liter) of water. A microgram per liter expresses 

the concentration of chemical constituents in solution as weight (micrograms) of solute per unit volume (liter) of water. Microsiemens per centimeter (uS/cm) at 

25 degrees Celsius (°C) expresses the capability of a unit volume of water to conduct 

an applied electrical current.

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 both the United States and Canada, formerly called the "Sea 

Level Datum of 1929."

Altitude: As used in this report, "altitude" refers to distance above or below sea level.

IV Ground Water Near Newton. Jasper County, Iowa
Ground Water Near Newton, Jasper County, Iowa

By Robert C.Buchmiller

Abstract

The U.S. Geological Survey, in cooperation 

with the city of Newton, Iowa, conducted an 

investigation of the ground-water resources of 

Jasper County, Iowa, near Newton during 

1999-2001. The purpose of the investigation was 

to provide additional information on the South 

Skunk River alluvial aquifer from which Newton 

obtains its present municipal supply and to summarize the available information on other groundwater resources in the county.

The South Skunk River alluvial aquifer consists of unconsolidated deposits of sand and 

gravel of glacial and fluvial origin. These deposits 

overlie bedrock composed primarily of shale and 

limestone of Pennsylvanian or Mississippian age. 

Information on the South Skunk River alluvial 

aquifer and other Jasper County alluvial aquifers 

is limited to a few test holes in a few locations. 

Additional thickness and lithologic information 

was collected using seismic refraction and testhole drilling to increase the understanding of the 

South Skunk River alluvial aquifer near Newton. 

Water-level and water-quality information also 

was collected.

The alluvial deposits along the South Skunk 

River near Newton range from less than 30 to 

more than 60 feet thick. Three areas of deposits 

exceeding 60 feet thick occur near the present city 

of Newton well field about 5,000 feet west of 

the present well field, at the present well field, 

and about 5,000 feet southeast of the present 

well field.

Ground water in the South Skunk River alluvial aquifer near the Newton well field flows 

toward the municipal well field. Ground-water 

levels on the well-field side of the South Skunk

River were lower than water levels in the 

river, indicating flow from the river toward the 

well field.

The water quality in the South Skunk River 

and the alluvial aquifer was similar, except most 

ground-water samples contained low dissolvedoxygen concentrations. The low dissolved-oxygen 

concentrations in ground water resulted in high 

concentrations of iron and manganese in some 

locations and reduced forms of nitrogen.

INTRODUCTION

The city of Newton, Iowa, obtains its municipal 

water supply from the alluvial sand and gravel aquifer 

along the South Skunk River. Twenty-one wells ranging in depth from 44 to 57 ft are completed in the alluvial aquifer about 5 mi southwest of the city. Each 

well yields between 100 and 700 gal/min of water. 

During the summer of 2000, an additional well was 

drilled to underlying bedrock and completed in the 

Jordan aquifer for municipal water supply.

Additional water-supply wells in a new well field 

may be required by the city of Newton during the next 

10 years to meet future demand from commercial, 

industrial, and domestic users. Average daily groundwater withdrawals for municipal needs are expected to 

increase from 4.5 Mgal/d in 1998 to 8 Mgal/d by 

2007 (M. Hoffert, city of Newton, oral commun., 

May 1998).

To help address concerns about future sources of 

water supply, the U.S. Geological Survey (USGS), in 

cooperation with the city of Newton, conducted a 

study from 1999 to 2001 to provide information about 

the sources of ground water (unconsolidated and bedrock aquifers) in Jasper County, particularly in the 

Newton area. The objectives of the study were to: 

(1) describe the thickness, lithology, and water quality 

of the unconsolidated alluvial deposits in the South

Introduction
Skunk River Valley in the Newton area, and (2) briefly 

summarize available information on ground-water 

resources in the Jasper County area.

Purpose and Scope

The purpose of this report is to describe results of 

the study on ground-water sources in the Newton and 

Jasper County area (fig. 1). Available hydrologic and 

geologic information was compiled from the scientific 

literature and previous studies. New thickness, lithologic, and water-quality data for unconsolidated alluvial deposits were collected for this study from 

October 1999 through October 2000 from a part of 

the South Skunk River Valley near Newton's 

present municipal supply (fig. 2) and are presented in 

this report.

Information from this study will contribute to 

understanding the characterization and flow-system 

definition of local and regionally important alluvial 

aquifers. Collection of hydrogeologic data from alluvial aquifers will enhance databases needed for understanding and constructing flow models for simulating 

interactions between ground and surface water, furnish 

results needed by managers for planning and operation 

of public-water supplies, and provide information that 

is transferable to present and (or) future public-water 

supplies utilizing alluvial aquifer sources.

Previous Investigations

Few studies have been conducted that are related 

to the water resources associated with the unconsolidated deposits in the study area . The geology, physiography, and drainage of Jasper County are described 

in Williams (1904). Norton and others (1912) describe 

the water resources of Jasper County, including the 

study area-. Information on the occurrence, availability, 

quality, and utilization of water in central Iowa is presented in Twenter and Coble (1965). The bedrock 

topography of central Iowa is mapped by Hansen 

(1985). Bruner and Hallberg (1987) describe the 

ground-water quality of the entire Skunk River Basin, 

particularly with regard to the occurrence of nitrate. 

Information about water quality and geology is available for the Mississippian aquifer (Horick and Steinhilber, 1973), the Silurian-Devonian aquifer (Horick, 

1984), and the Jordan aquifer (part of the CambrianOrdovician aquifer system) (Horick and Steinhilber,

1978). The recharge to, and ground-water movement 

in, the St. Peter and Jordan aquifers are evaluated by 

Burkart and Buchmiller (1990). A comprehensive 

summary of geology and hydrologic characteristics for 

the major aquifers in Iowa is presented by Olcott 

(1992).

A geological and geophysical study of a small area 

of the flood plain near the Newton well fields was conducted by Lyle Sendlein in 1969 (L. Sendlein, written 

commun., June 1969). The objective of the study was 

to determine the altitude of the bedrock surface 

beneath the flood plain. Areas that appeared to be 

deeper to bedrock were believed to contain greater 

thicknesses of sand and gravel. Fifteen depth-tobedrock determinations were made at selected locations using seismic-refraction techniques. From these 

interpretations, well logs, and rock outcrops, the altitude of the bedrock surface in the flood plain was 

mapped. The study concluded that the thickness of the 

alluvium is relatively uniform and that 47 ft (±10 ft) of 

sand and gravel overlie the bedrock.

Areas of the South Skunk River alluvial aquifer 

near the present municipal supply wells have been 

investigated by the city of Newton to determine the 

occurrence of sand and gravel deposits of sufficient 

thickness to construct additional municipal wells. Sixteen test holes were drilled in 1980 at selected locations southwest and southeast of the present well fields 

(Layne-Western Company, Inc., written commun., 

1980). Results from this drilling indicated a highly 

variable thickness of sand and gravel and varying 

types of materials underlying the alluvial aquifer. Six 

of the test holes indicated limestone as the uppermost 

bedrock underlying the aquifer. Seven test holes penetrated shale beneath the alluvial aquifer. The remaining three test holes indicated clay or glacial till 

underlying the aquifer. Depths to bedrock varied from 

42 to 66 ft below land surface. Thicknesses of sand 

and gravel ranged from 25 to 49 ft. Some well logs 

reported encountering wood, coal, or other vegetative 

debris within the aquifer.

Two additional test holes were drilled in 1998 

southeast of the well fields (North way Well and Pump 

Co., written commun., 1998). One test hole reported 

shale underlying the alluvial aquifer, whereas the second reported limestone. Depths to bedrock were 53 

and 44 ft, respectively. Sand and gravel thicknesses 

were 27 and 32 ft, respectively.

Ground Water Near Newton, Jasper County, Iowa
MINNESOTA

41°45' 

41°37'30"

LZ:

Base from U.S. Geological Survey digital data 1:100,000,1991 

Universal Transverse Mercator projection 

Zone 15 8 KILOMETERS

Figure 1. Location of Jasper County and Newton study area in Iowa.

Introduction 3
07' 93°06'

41°39'-

41°38'-

South Skunk 

River at 

Neptune St.

Layne 10.80\ Northway R-98-01 (22)

\

A^V /_ Lavne

-8( Northway R-98-02 (23)

\

1 I

Base from U.S. Geological Survey digital data 1:100,000,1991 

Universal Transverse Mercator projection 

Zone 15 EXPLANATION

Data-collection sites

Layne 133 Test hole and identifier

19 Municipal well and identifier 

N12-52© USGS test hole/observation well and identifier 

River at Hwy 14^ Surface-water measurement site and identifier

A A' Trace of seismic geophysical section 

A-A' through L-V

 Boundary between upland area and river valley

400 800 METERS

Figure 2. Location of data-collection sites in South Skunk Valley near Newton, Iowa.

4 Ground Water Near Newton, Jasper County, Iowa
Description of Study Area

Newton, Iowa, is located on the rolling, dissected 

uplands of the Southern Iowa Drift Plain in Jasper 

County (Prior, 1991). The city is located in the approximate center of the county and lies about 5 mi northeast of the South Skunk River Valley. The South 

Skunk River, one of two major drainage systems that 

receive runoff from Jasper County, drains about onehalf of the county and originates in north-central Iowa. 

The other major drainage system, north and east of 

Newton, is the North Skunk River, which receives runL 

off from about one-third of the county. The two rivers 

join about 45 mi southeast of Jasper County before 

continuing on to the southeast to join the Mississippi 

River. Small areas in the southwest and northeast corners of the county drain to the Des Moines and Iowa 

Rivers, respectively.

The topography of Jasper County is dominated by 

steeply rolling hills eroded into glacial drift. Valleys of 

large rivers contain significant deposits of alluvial 

material. The thickness of the unconsolidated surficial 

deposits ranges from zero in small areas in the deeper 

river valleys where bedrock is exposed to about 200 ft 

beneath upland areas. The underlying bedrock consists 

of a thick sequence of sedimentary rocks. This geologic framework contains the hydrogeologic units 

described in table 1.

An area of about 9.6 mi2 along the South Skunk " 

River Valley southwest of Newton was selected for 

additional data collection during this study (fig. 1). 

The South Skunk River Valley is about 1.5 to 2 mi 

wide in ,the study area. The land-surface altitude of the 

river valley in this area varies from about 765 to. 775 ft 

above sea level, and adjacent upland areas rise to about 

900 ft. The South Skunk River in this area was channelized and straightened during the first quarter of the 

20th century.

Streamflow in the South Skunk River is measured 

about 6 mi upstream from the study area at the USGS 

streamflow-gaging station South Skunk River at Colfax (station 05471050) 1 . Annual mean daily streamflow at this site is about 622 ft3/s (October 1985 

through September 2000). However, during October 

1999 through September 2000, mean daily Streamflow 

averaged 96.3 ft3/s due to less-than-normal

'Real-time stage and discharge data for this>stream-gaging station can 

be accessed through the Interact at URL http://ia.usgs.gov/data.html.

precipitation in central Iowa (Nalley and others, 

2001).

Acknowledgments

The author thanks the city of Newton Waterworks 

staff for their assistance in gathering technical information and assisting in data collection. The author 

also thanks Peter Schulmeyer, Aimee Donnelly, and 

Dan Christiansen, USGS, for assisting with data collection and compilation. The author is grateful to landowners in the Newton area who granted access to their 

property for collection of data.

DESCRIPTION OF SOUTH SKUNK RIVER 

ALLUVIAL DEPOSITS NEAR NEWTON

The alluvial deposits associated with the South 

Skunk River Valley near Newton consist of stratified 

sand and gravel deposits of glacial and fluvial origin. 

The upper 20 ft of the alluvial deposits are interbedded 

with clay and silt lenses and overlain by a developed 

soil horizon. Alluvial deposits below a depth of about 

20 ft typically become coarser with depth. Although 

all the unconsolidated materials described in available 

geologic logs could be expected to yield water, only 

those materials that are described as having a 

"medium" sand or larger-grained material are considered to be the alluvial aquifer for the purposes of this 

report. Therefore, the thickness of the alluvial aquifer, 

in general, is considered to be the amount of sand and 

gravel between about 20 ft below land surface and the 

top of the bedrock surface.

Collection of Seismic-Refraction and 

Observation-Well Data

Seismic refraction and observation-well drilling 

were used by the USGS to collect new geologic infor-. 

mation for the unconsolidated deposits in the study 

area. Seismic refraction was used to determine the 

depth to bedrock below land surface and to estimate 

the thickness of unconsolidated deposits. Observation 

wells and test holes that penetrated the alluvium were 

used to provide additional geologic information and to 

provide verification of the seismic interpretations at 

selected locations. Observation wells also were

Description of South Skunk River Alluvial Deposits Near Newton 5
Table 1. Description of hydrogeologic units in central Iowa

Hydrogeologic unit1

Approximate thickness in

central Jasper County Potential well yield 

(feet)1 Age of rock unit2 (gallons per minute) Lithology1

Alluvial, glacial-drift, and buried- 0-100 Quaternary 

channel aquifers 

Confining unit 50-100 Pennsylvanian Very small

Less than 20 to more than 500

Mississippian aquifer 250-300

Confining unit 200-250

Devonian aquifer 500-550

Confining unit 500-550

Cambrian-Ordovician System 500-550

St. Peter aquifer 30-40

Jordan aquifer 40-50

Confining unit 350-550

Mississippian Less than 20 to 50

Mississippian

and

Devonian 

Devonian

Very small

Less than 20 

Silurian Very small

and

Ordovician

Ordovician and More than 1,000 

Cambrian

Cambrian Very small

Sand, gravel, silt, clay, 

and boulders.

Shale, sandstone, thin

limestone, and coal. 

Limestone, dolomite,

and shale (gypsum

and anhydrite occur

locally). 

Shale, siltstone,

limestone, and

dolomite. 

Limestone, dolomite,

and shale. 

Dolomite, shale, chert,

limestone, and

sandstone. 

Sandstone and dolomite.

Sandstone, shale, 

siltstone, and 

dolomite.

Modified from Twenter and Coble (1965).

2Age classification of rock units are those of the Iowa Department of Natural Resources, Geological Survey Bureau.

constructed to provide for collection of water-level 

measurements and water-quality samples.

Using the seismic-refraction method, the contact 

between alluvium and bedrock is determined from a 

contrast in seismic acoustic velocity. Seismicrefraction velocities ranged from less than 1,000 ft/s in 

unsaturated unconsolidated materials to about 

12,000 ft/s in the bedrock. The refraction system consisted of a 12-channel seismograph, geophones 

(receivers), an energy source, and related equipment. 

Geophones were placed in lines as much as 1,100 ft 

long in the areas of interest, and seismic energy was 

supplied by detonating an explosive mixture of ammonium nitrate and nitromethane. Data were recorded on 

seismograms and then downloaded onto computer 

disk. Onsite calculations of the data, made on the basis 

of equations given by Haeni (1988), were used to maximize the quality of data-collection geometries. Final 

processing of the data was done using a modeling program, SIPT2V4.1 (Rimrock Geophysics, Inc., 1995) 

assuming a three-layer system unsaturated unconsolidated materials, saturated unconsolidated materials, 

and bedrock. An assumption of the modeling program 

is that refraction acoustic velocities increase with

depth. More than 35,000 linear ft of seismic-refraction 

data were collected during October-November 1999. 

Seismic-refraction data were collected at sections A-A' 

through L-L shown in figure 3. The latitude and 

longitude of the seismic shot points along each seismic section were determined by a global positioning 

system (GPS).

A total of 12 test holes were drilled by the USGS 

during the study (fig. 2), with an average depth of 

44 ft. All test holes were drilled with 3.25-in. insidediameter (ID) hollow-stem augers. Test holes were 

drilled to bedrock or to the limits of the drill rig being 

used. Samples of auger cuttings were collected at 

major lithologic changes. Observation wells were constructed at the test-hole locations by lowering 2.5 ft of 

0.020-in. slot-size, polyvinyl chloride (PVC) schedule 

40, flush-threaded, 2-in. diameter well screens and 

riser pipe inside the auger flights. Wells were installed 

near the bottom of the sand and gravel deposits overlying the bedrock. The annular space around the screen 

and riser was filled with native materials to within 

about 8 ft of land surface. The upper 8 ft were filled 

with bentonite clay and cement to prevent surface runoff from entering the borehole. A lockable, protective 

casing was cemented in place over the protruding

6 Ground Water Near Newton. Jasper County. Iowa
A' D' EXPLANATION

[ I Unsaturated,

unconsolidated materials

^H Saturated,

unconsolidated materials

^H Undifferentiated 

bedrock

~ Test hole and 

I identifier

800 T

Trace of sections shown in figure 2 Vertical scale exaggeration x 20

1,000 2,000 FEET 

__I

200 400 METERS

Figures. Geologic sections based on seismic-refraction and test-hole data.
800 T

COo

680

800 T

780-760-740-

Trace of sections shown in figure 2 Vertical scale exaggeration x 20

200

1,000 l 2,000 FEET __I

400 METERS

Figure 3. Geologic sections based on seismic-refraction and test-hole data Continued
portion of the riser pipe. Wells were pumped after 

construction to develop the sand pack surrounding 

the screen.

Table 2 lists observation-well locations and associated geologic information. The prefix 'N' designates 

observation wells drilled by USGS personnel in 1999. 

Information about unconsolidated materials, including 

depth to bedrock and sand and gravel thickness, for 

test holes designated 'Layne' were obtained from 

Layne-Western Company, Inc. (written commun. to 

Newton Waterworks, 1980). Additional test-hole data 

were obtained from Northway Well and Pump Company (written commun. to Newton Waterworks, 1998) 

and are designated 'Northway'.

Thickness and Lithology

Descriptive logs of USGS, Layne-Western, and 

Northway test holes drilled in the study area (table 2) 

indicate shale, clay, glacial till, or limestone underlie 

the sand and gravel of the alluvial aquifer. Gray clay or 

glacial till can have the same appearance and drilling 

characteristics in the study area as a soft gray shale, 

and additional analysis would be required to determine 

the exact lithology of these deposits. For the purposes 

of this report, wells or test holes penetrating gray clay 

or glacial till beneath the sand and gravel are assumed 

to be shale and the top of the bedrock surface. On the 

basis of a limited number of wells and test holes that 

penetrate deeper into the bedrock, this gray shale or 

clay layer is from 0 to about 15 ft thick and overlies a 

hard white limestone. Depths to bedrock in wells and 

test holes ranged from 34 to more than 60 ft. The 

greatest depths to bedrock occurred in the southeastern 

part of the well field area where a thicker layer of sand 

and gravel may be a terrace or dune deposit.

Seismic-refraction data can be used to identify 

boundaries between unsaturated and saturated unconsolidated materials and saturated unconsolidated materials and bedrock. Seismic-refraction data do not 

differentiate between the types of material comprising 

the unconsolidated material. Therefore, thicknesses of 

aquifer material are inferred from the total thickness of 

unconsolidated deposits within the South Skunk River 

Valley. Additional test drilling is needed to confirm the 

interpreted depth to bedrock in areas where test-hole 

data are not available and to determine the type of 

material composing the unconsolidated deposits.

Seismic-refraction data show variations in the 

depth to the bedrock surface in places in the study area 

(fig. 3). The removal of bedrock materials through erosion and weathering may explain local differences in

depth to bedrock and type of material composing the 

bedrock surface seen in the descriptive logs of wells 

and test holes fully penetrating the alluvium. For 

example, the two Northway test holes listed in table 2 

are about 1,300 ft apart, yet the depth-to-bedrock varies by 9 ft. The type of material composing the bedrock surface in the two test holes also is dissimilar.

Figure 4 shows the altitude of the bedrock surface 

in feet above sea level in the study area. This map was 

prepared from depth-to-bedrock data from wells, test 

holes, and seismic-refraction shot-point locations. Figure 4 shows three areas in the study area where the 

bedrock surface is lower than 720 ft above sea 

level an area about 5,000 ft west of the present well 

field area, the present well field area, and an area about 

5,000 ft southeast of the present well field area.

The thickness of unconsolidated alluvial deposits 

is shown in figure 5. This map was created by a geographic information system (GIS) process. A grid of 

the altitude of the interpreted bedrock surface was created and subtracted from a grid of the land-surface 

altitude in the study area to provide a gridded estimate 

of the thickness of unconsolidated deposits.The greatest thicknesses of unconsolidated alluvial deposits, in 

excess of 60 ft, coincide with the areas of lowest bedrock-surface altitude. The altitude of the flood-plain 

land surface is relatively uniform, and the deeper bedrock-surface areas appear to be erosional channels in 

the bedrock that have been subsequently filled by 

unconsolidated deposits.

Ground-Water Flow

Water levels were measured in observation and 

municipal water-supply wells during February, June, 

and October 2000 with calibrated steel tapes or electric line. Altitudes of measuring points on the wells 

were surveyed to sea-level datum, and all water-level 

measurements were converted to altitudes above sea 

level. In addition, reference points surveyed to sea 

level were established on bridge crossings^over the 

South Skunk River near the upstream and downstream 

extremes of the study area. River stages of the South 

Skunk River were measured to determine altitude and 

gradient of surface water in the study area at the time' 

of ground-water-level measurements. Static 

(nonpumping) water levels were measured in municipal wells. There was less than 10-ft difference between 

water levels at different well locations. Water levels 

measured during this study are given in table 3.

River stages in the South Skunk River were similar for each measurement date, and the gradient

Description of South Skunk River Alluvial Deposits Near Newton 9
Table 2. Description of drilled test holes and geologic information

Test-hole

identifier1

(fig. 2)

Location land net2 

(latitude, longitude) Geologic unit

Drillers log/cuttings description 

(feet below land surface)

Nl-33 T20N-R79W-12DCDA Quaternary-age alluvium 

(41° 39' 38.29", 93° 07' 16.47")

N4-51

Undifferentiated Paleozoic

T79N-R20W-13DBCC Quaternary-age alluvium 

(41° 38'55.69", 93° 07'32.01")

T79N-R19W-18CBAB Quaternary-age alluvium 

(41° 39' 06.57", 93° 06' 44.28")

T79N-R19W-19ADAA Quaternary-age alluvium 

(41° 38'28.28", 93° 05'46.83")

N6-46 T79N-R19W-19DDDA Quaternary-age alluvium 

(41° 37' 53.00", 93° 05' 47.06")

0-6, Dark-brown silt, clayey 

6-12, Light-brown silt 

12-15, Light-brown sand, silty, fine 

15-23, Sand, fine

23-32, Medium-brown sand, fine to medium, well 

rounded

32-33, Gray-brown sand, with large gravel

33-34, Clay, glacial till, stiff 

34, Bedrock

0-1, Lime, fill

1-2, Dark-brown soil, silty, small pebbles

2-3, Medium-brown soil, silty, fine sand

3-9, Medium-brown silt, soft 

9-11, Gray silt, sandy, soft, damp

11-12, Fine sand, oxidized

12-18, Dark-brown sand, fine, wet at 17 feet

18-20, Medium-brown sand, fine to medium, some silt

20-24, Gray sand, fine to coarse

24-44, Gray sand, fine to coarse, pea gravel

44-47, Gravel

47-48, Clay, glacial till, hard

0-3, Dark-brown soil, silty

3-4, Dark-brown silt, clayey

4-5, Black silt, clayey

5-9, Dark-brown silt, clayey

9-10, Dark-brown sand, silty

10-14, Brown sand, fine, some silt lenses

14-22, Light-brown sand, fine

22-51, Medium-brown sand, fine to medium, gravel at

45 feet 

51, Clay, glacial till, hard

0-4, Medium-brown sand, fine

4-5, Dark-brown sand, silty, fine

5-10, Dark-brown silt, sandy, stiff

10-17, Medium-brown sand, silty, fine, dark brown at

12-14 feet, wet at 17-18 feet 

17-25, Dark-brown sand, fine 

25-42, Medium-brown sand, fine to coarse 

42, Clay, glacial till

0-4, Black soil, silty

4-8, Dark-brown silt, clayey, stiff

8-10, Medium-brown silt, clayey, some sand, damp at

10 feet

10-12, Gray sand, clayey, silty 

12-20, No returns, soft at 15 feet 

20-40, Gray sand, fine, soupy 

40-45, Same as above only coarser, cleaner, fine to

pea-size gravel

45-46, Gravel, large

46-47, Clay, glacial till, stiff

10 Ground Water Near Newton, Jasper County, Iowa
Table 2. Description of drilled test holes and geologic information Continued

Test-hole

identifier1

(fig. 2)

Location land net2 

(latitude, longitude) Geologic unit

Drillers log/cuttings description 

(feet below land surface)

N7-32

N8-45

N10-45

T79N-R19W-19BADD

(41° 38'30.53", 93° 06'22.26")

Quaternary-age alluvium

T79N-R19W-19CADD Quaternary-age alluvium 

(41° 38'02.34", 93° 06'21.55")

T79N-R20W-11CDAD Quaternary-age alluvium 

(41° 39' 40.24", 93° 08' 46.28")

T79N-R20W-14CBDD Quaternary-age alluvium 

(41° 38' 53.92", 93° 09' 00.87")

T79N-R20W-23AAAA Quaternary-age alluvium 

(41° 38'40.02", 93° 08'10.74")

0-1, Dark-brown soiI7 silty 

1-4, Dark-brown clay, silty 

4-6, Medium-brown silt, clayey, stiff from 5-6 feet

6-7, Gray-brown silt, sandy

7-8, Brown sand, fine

8-12, Gray sand, silty 

12-20, No returns, very soft 

20-38, Gray sand, coarse 

38-39, Gravely 

39, Clay, glacial till, very hard

0-2, Dark-brown soil, silty 

2-4, Dark-brown silt

4-5, Medium-brown silt, sandy

5-6, Medium-brown sand, silty, fine

6-12, Dark-brown sand, silty, fine

12-30, Gray sand, fine to medium, small gravel at 22 feet,

wet 

30-46, Same as above, gravel lense at 43 feet, large

gravel lense at 45 feet 

46-47, Clay, glacial till, coal, very hard

0-3, Soil and road fill 

3-6, Dark-brown silt, very stiff 

6-8, Medium-brown clay, silty, softer than above 

8-12, Medium-brown sand, silty, fine 

12-18, Medium-brown sand, fine, wet at 15 feet 

18-25, As above, coarser

25-44, Gray-brown sand, fine to very coarse, soupy, some 

pea gravel

44-45, Gravel

45-46, Clay, glacial till, very stiff

0-2, Dark-brown soil, silty

2-4, Medium-brown silt, clayey

4-9, Medium-brown clay, silty, stiff

9-15, Medium-brown silt, sandy, soft, no returns

10-18 feet

15-25, Medium-brown sand, fine , 

25-35, Medium-brown sand, fine to coarse 

35-47, Medium-brown to gray sand, fine to very coarse 

47-48, Clay, glacial till, very hard

0-3, Dark-brown soil, silty

3-5, Dark-brown silt

5-7, Dark-brown silt, clayey, very stiff

7-14, No returns, soft

14-25, Gray-brown sand, silty, fine, wet

25-30, Gray-brown sand, some silt, fine to coarse

30-42, Gray-brown sand, fine to coarse

42-43, Gravel, very large

43, Could not penetrate large gravel

Description of South Skunk River Alluvial Deposits Near Newton 11
Table 2. Description of drilled test holes and geologic information Continued

Test-hole

identifier1

(fig. 2}

Location land net2 

(latitude, longitude) Geologic unit

Drillers log/cuttings description 

(feet below land surface)

N12-52 T79N-R20W-25AAAA Quaternary-age alluvium 

(41° 37'48.54", 93° 06'58.84")

N13-41

Northway 

R-98-01

Northway 

R-98-02

Layne TH1

T79N-R19W-30ADDD Quaternary-age alluvium 

(41° 37'22.91", 93° 05'47.02")

T79N-R19W-18CBAB Quaternary-age alluvium 

(41° 39' 04.50", 93° 06' 49.27")

Undifferentiated Paleozoic

T79N-R19W-18CDBB Quaternary-age alluvium 

(41° 38'51.98", 93° 06'42.59")

Undifferentiated Paleozoic 

T79N-R20W-13CDAB Quaternary-age alluvium

Undifferentiated Paleozoic

0-2, Medium-brown silt : 

2-4, Dark-brown silt

4-5, Dark-brown silt, clayey, stiff

5-7, Medium-brown silt, clayey, stiff

7-8, Medium-brown clay, silty, softer

8-9, No returns

9-10, Sand and clay, oxidized

10-11, Medium-brown silt, sandy

11-13, No returns

13-14, Sand, fine, oxidized, wet

14-20, Medium-brown sand, silty, fine

20-25, As above, fine to medium

25-48, As above, fine to very coarse, little silt, some pea

gravel

48-51, Gravel 

51-55, Gray sand, coarse 

55-56, Gravel, very coarse 

56, Clay, glacial till, stiff

0-1, Dark-brown soil, silty

1-2, Dark-brown silt, stiff

2-4, Medium-brown silt, stiff

4-6, Medium-brown silt, clayey

6-9, Medium-brown clay, silty, very soft

9-14, No returns, soft

14-20, Medium-brown sand, silty, fine to medium

20-25, Gray-brown sand, fine to medium

25-30, Gray sand, fine to medium

30-40, Gray-brown sand, fine to mostly coarse

40-44, As above, fine sand to pea gravel, mostly very

coarse sand 

44-45, Gravel, very large, unable to penetrate gravel

0-26, Clay, sandy

26-42, Sand, fine to medium, and gravel 

42-53, Sand, fine to coarse, and gravel 

53-60, Shale, gray

0-4, Top soil

4-12, Sand, fine

12-44, Sand, fine to coarse, and gravel

44-50, Limestone, with gray shale streaks

0-4, Top soil, black

4-9, Clay, dark brown, gumbo

9-10, Sand, brown, silty

10-16.5, Sand, dark grayish white, black river mud and

some wood cuttings

16.5-20, Sand and gravel, fine to medium, grayish white 

20-25, Sand and gravel, test holes to coarse dark grayish

white

25-30, Sand and gravel, fine to medium, grayish white 

30-35, Sand and gravel, fine to medium, grayish white,

cobble at 34 feet 

35-40, Sand and gravel, medium to coarse, grayish white,

with cobbles

40-42, Sand and gravel, grayish white, with cobbles 

42, Limestone, soft

12 Ground Water Near Newton, Jasper County, Iowa
Table 2. Description of drilled test holes and geologic information Continued

Test-hole

identifier1 

(fig. 2)

Location land net2 

(latitude, longitude) Geologic unit

Drillers log/cuttings description 

(feet below land surface)

Layne 2 T79N-R20W-13CDAB Quaternary-age alluvium

Layne 3 T79N-R20W-13CDDB

Undifferentiated Paleozoic 

Quaternary-age alluvium

Layne 4 T79N-R20W-13CDBC

Undifferentiated Paleozoic

Quaternary-age alluvium

Undifferentiated Paleozoic

0-3, Top soil, black .

3-9.5, Clay, brownish yellow, silty

9.5-10, Sand, brown, silty

10-14.5, Clay, dark gray, with coal and lenses of fine,

dark-gray sand

14.5-30, Sand and gravel, fine to medium, gray 

30-35, Sand and gravel, fine to medium, with some

coarse pea-size gravel in sand 

35-40, Sand and gravel, fine to medium, gray, with coarse

sand and cobbles from 35-37 feet 

40-43.6, Sand and gravel, medium to fine, with some

coarse sand and cobbles 

43.6, Limestone, soft

0-3, Top soil, black

3-12.5, Clay, dark brownish yellow, gumbo

12.5-15, Sand and gravel, with lenses of dark brownishblack gumbo clay with some wood and coal cuttings

15-18, Clay, dark-black gumbo, with fine sand lenses

18-20, Sand and gravel, fine to medium

20-40, Sand and gravel, fine to medium, dark gray, with a 

large amount of dead vegetation and wood cuttings

40-46, Sand and gravel, fine to medium, with some 

coarse, no dead vegetation

46-50, Till, dark gray, layered with black gumbo

50-62, Clay, grayish white, with vegetation and coal

62-71.5, Limestone, soft and gritty, clay like, not in chip 

form

71.5, Limestone, white, very hard, chip form

0-2, Top soil, black

2-7, Clay, dark brown, yellow

7-8, Sand, fine, brownish yellow

8-10, Clay, brown, yellow

10-15, Sand, fine, brown yellow, with layers of brownyellow clay with fine sand and gravel that have wood 

and coal cuttings on top of dark-gray clay

15-17.5, Dark-gray coal at 17.5 feet

17.5-20, Sand and gravel, fine to medium

20-25, Sand and gravel, fine to medium, with some 

coarse, gray

25-30, Sand and gravel, fine to medium, with wood and 

dead vegetation

30-46, Sand and gravel, fine to medium, with some 

coarse

46-50, Shale, dark gray

50, Limestone, hard

Description of South Skunk River Alluvial Deposits Near Newton 13
Table 2. Description of drilled test holes and geologic information Continued

Test-hole

identifier1

(fig. 2}

Location land net2 

(latitude, longitude) Geologic unit

Drillers log/cuttings description 

(feet below land surface)

Layne 5 T79N-R20W-13DBCC Quaternary-age alluvium

Undifferentiated Paleozoic

Layne 1.0-80 T79N-R19W-18CBDB Quaternary-age alluvium

Undifferentiated Paleozoic

Layne 11 T79N-R19W-18BCCD Quaternary-age alluvium

Undifferentiated Paleozoic

0-2, Top soil, black 

2-5, Black river gumbo 

5-9, Black river gumbo

9-10, Clay, yellow, brown

10-15, Sand and gravel, fine to medium

15-20, Sand and gravel, fine to medium, with some

coarse grayish dark sand 

20-25, Sand and gravel, fine to medium, gray 

25-30, Sand and gravel, fine to medium, gray, with good

size pea gravel within 

30-35, Sand and gravel, fine to medium, with some

coarse, cobbles at 33 feet

35-40, Sand and gravel, fine to medium, very clean 

40-43, Sand, medium to coarse, brownish white 

43-58, Shale, gray, with grayish-brown till on top of

shale, shale turns to light gray to white 

58-69, Shale, white, with particles of grit that turns to

chips of limestone 

69, Limestone, hard 

0-5, Sand, fine 

5-12, Sand, fine, clay 

12-17, Clay, brown 

17-25, Sand, fine to coarse, buff color 

25-66, Sand and gravel, coarse 

66-73, Shale, blue 

73-75, Limestone, shaly

0-13, Sand, very fine, yellowish brown

13-15, Clay, yellow

15-20, Sand, very fine, yellow brown, with lenses of

yellow clay

20-23, Sand, very fine, yellow brown 

23-25, Sand, fine, brown 

25-30, Sand and gravel, fine to medium, with some

coarse 

30-35, Sand and gravel, medium to coarse, turns to fine

sand at 31.5 feet

35-40, Sand and gravel, fine to medium, brown 

40-45, Sand and gravel, fine, with some medium, brown 

45-55, Sand and gravel, fine, with some medium,

brownish white 

55-59, Sand and gravel, fine to medium, with some

coarse, brown 

59, Limestone, grayish white, hard

14 Ground Water Near Newton, Jasper County, Iowa
Table 2. Description of drilled test holes and geologic information Continued

Test-hole

identifier1

(fig. 2)

Location land net2 

(latitude, longitude) Geologic unit

Drillers log/cuttings description 

(feet below land surface)

Layne 12 T79N-R20W-13DBBA Quaternary-age alluvium

Layne 13 T79N-R20W-13DBAA Quaternary-age alluvium

Layne 14 T79N-R19W-18CDBB

Undifferentiated Paleozoic 

Quaternary-age alluvium

0-5, Gumbo, black

5-8, Gumbo, yellowish black

8-10, Clay, yellow

10-11.5, Clay, yellow, with lenses of fine sand

11.5-15, Sand and gravel, fine to medium, brown

15-20, Sand and gravel, fine to medium, brown

20-25, Sand and gravel, fine to medium, with wood and

dead vegetation from 23-25 feet 

25-30, Sand and gravel, mostly fine to medium, gray,

wood stops at 26 feet 7 inches 

30-35, Sand and gravel, medium to coarse, with some

fine cobbles at 32-35 feet 

35-37, Sand and gravel, mostly fine to medium 

37-43, Sand and gravel, fine, with some medium, grayish

white

43-45.5, Sand and small cobbles, fine, grayish white 

45.5-55, Till, blue gray

0-2, Top soil, black 

2-4, Gumbo, black 

4-7, Gumbo, yellow 

7-9, Clay, yellow

9-10, Sand, rusty brown

10-15, Sand and gravel, fine, gray

15-20, Sand and gravel, fine to medium, gray

20-25, Sand and gravel, fine, with some medium, dead

vegetation from 23-24.5 feet 

25-30, Sand and gravel, fine to medium, with some

coarse, gray 

30-35, Sand and gravel, fine to medium, with some

coarse cobbles from 32-34.5 feet 

35-40, Sand and gravel, medium to coarse, with some

fine cobbles from 36-40 feet, mixed 

40-43.75, Sand and gravel, medium to coarse, with

cobbles, gray 

43.75-44, Limestone, light yellow, very hard

0-5, Sand, very fine, brown

5-8, Till, brown

8-10, Till, brownish gray

10-13.4, Clay, brownish gray, silty

13.4-16, Sand, very fine, brownish gray

16-20, Sand and gravel, fine to medium, brownish gray

20-30, Sand and gravel, fine to medium, brown

30-35, Sand and gravel, medium to coarse, with some

fine cobbles at 32-34 feet 

35-38, Sand and gravel, fine, white 

38-40, Sand and gravel, fine to medium, brown 

40-45, Sand and gravel, fine to medium, with some

coarse 

45-49, Sand and gravel, medium to coarse, with small

boulders and large cobbles 

49-55, Clay, blue

Description of South Skunk River Alluvial Deposits Near Newton 15
Table 2. Description of drilled test holes and geologic information Continued

Test-hole

identifier1

(fig. 2)

Location land net2 

(latitude, longitude) Geologic unit

Drillers log/cuttings description 

(feet below land surface)

Layne 15 T79N-R19W-18CDBB Quaternary-age alluvium

Layne 16 T79N-R19W-18CCAB

Undifferentiated Paleozoic 

Quaternary-age alluvium

Layne 6-80 T79N-R19W-19BBCD

Undifferentiated Paleozoic 

Quaternary-age alluvium

Undifferentiated Paleozoic

0-2.5, Sand, very fine, brown 

2.5-5, Clay, brown 

5-8.7, Clay, brownish gray 

8.7-11, Clay, brown, silty

11-14, Clay, rusty brownish yellow, turning into very fine 

brownish-yellow sand

14-15, Sand, fine, grayish yellow

15-20, Sand and gravel, fine to medium, gray

20-25, Sand and gravel, fine, with some medium, grayish

white 

25-30, Sand and gravel, fine, with some medium, grayish

white 

30-35, Sand and gravel, fine to medium, gravel becoming

coarser 

35-40, Sand and gravel, medium to coarse, with pea

gravel and cobbles at 36-40 feet 

40-45, Sand and gravel, medium to coarse, without pea

gravel 

45-50, Sand and gravel, medium to coarse, with pea

gravel and cobbles within 

50-53.3, Sand and gravel, medium to coarse, with some

fine 

53.3, Limestone, white, very hard

0-2.5, Top soil, black, sandy

2.5-5, Gumbo, black

5-10, Clay, blackish gray yellow

10-13, Clay, yellowish gray, silty

13-15, Sand and gravel, fine, brown

15-20, Sand and gravel, fine to medium, with some

coarse

20-25, Sand and gravel, fine to medium, brown 

25-30, Sand and gravel, fine to medium, with some

coarse, brown 

30-35, Sand and gravel, medium to coarse, with some

fine, brown

35-40, Sand and gravel, fine, brownish white 

40-45, Sand and gravel, very fine, white 

45-50, Sand and gravel, fine, with some medium,

brownish white

50-54, Sand and gravel, fine to medium, brown 

54, Limestone, very hard

0-5, Soil, black

5-7, Clay, sandy

7-12, Sand, fine to coarse

12-13, Wood log

13-32, Sand and gravel, coarse, blue and white 

32-44, Gravel and coarse sand, some fine

44-45, Boulders and gravel

45-46, Gravel and clay

46-59.5, Shale, gray 

59.5-60, Limestone, shaley

16 Ground Water Near Newton. Jasper County, Iowa
Table 2. Description of drilled test holes and geologic information Continued

Test-hole

identifier1

(fig. 2)

Location land net2 

(latitude, longitude) Geologic unit

Drillers log/cuttings description 

(feet below land surface)

Layne7-80 T79N-R19W-19BBDC Quaternary-age alluvium

Layne 8-80 T79N-R19W-18CCDA

Undifferentiated Paleozoic

Quaternary-age alluvium

Layne 9-80 T79N-R19W-18CCAB

Undifferentiated Paleozoic

Quaternary-age alluvium

Undifferentiated Paleozoic

0-7, Soil, black

7-8, Sand, fine

8-12, Clay, brown

12-16, Sand, coarse, blue and white

16-17, Clay, blue

17-37, Sand and gravel, coarse, blue and white

37-44, Sand, fine to coarse

44-47, Gravel and boulders

47-55, Shale, gray

55-62, Limestone, gray, shaley

0-5, Soil, black .

5-15, Clay, blue gray

15-27, Sand and gravel, coarse, blue and white

27-44, Sand, fine to coarse

44-46, Gravel and boulders

46-47, Shale, gray

47-54, Sandstone 

54-57, Shale, gray 

57, Limestone

0-12, Sand, fine to coarse

12-14, Clay, brown, sandy

14-28, Sand and gravel, coarse

28-40, Sand and gravel, coarse, some fine

40-58.5, Sand and gravel, coarse, some pebbles

58.5-62, Shale, blue black and gray

'Sites Nl-33 to N13-41 drilled by U.S. Geological Survey; November 3-11, 1999.

2Location indicated by township (north), range (west), and section. The letters after the section number represent successiveness subdivisions of 

the section assigned in a counterclockwise direction beginning with 'A' in the northeast quarter. The first letter indicates a 160-acre area. Each successive letter indicates an area one-fourth the size of the area represented by the previous letter.

between bridge measuring points was consistently 

0.44 ft per 1,000 ft of river channel.

Ground-water levels were higher during the 

June 2000 measurement than either the February or 

October 2000 measurements at all observation wells 

except wells Nl-33 and N4-51 (fig. 2), which are 

closest to the municipal well field. The highest waterlevel altitude occurred at well N10-45 in the west, 

upgradient part of the study area. The lowest waterlevel altitudes were measured at observation 

well N4-51, which is east and downgradient from the 

well field (fig. 2).

A potentiometric-surface map of water levels in 

the alluvial aquifer for the June 2000 measurements is 

shown in figure 6. Water levels are lowest in the well 

field area. Ground water flows radially towards the 

well field from adjacent areas of the alluvial aquifer. 

On the well-field side of the South Skunk River, water 

levels in the river are higher than adjacent groundwater levels except in the southeast corner of the study

area, indicating flow from the river toward the well 

field. Gradients between the river and the well field 

were similar on the other measurement dates as well.

Water Quality

Samples were collected from the observation 

wells and the South Skunk River at Highway 14 on 

June 6-8, 2000 (table 4). Samples were analyzed for 

dissolved oxygen, pH, specific conductance, temperature, and alkalinity onsite at the time of sample 

collection. Laboratory analyses consisted of common 

ions, nutrients, dissolved solids, bromide, iron, and 

manganese. Analyses were performed at the USGS 

National Water Quality Laboratory in Denver, 

Colorado.

Concentrations of specific conductance, alkalinity, 

calcium, magnesium, sodium, bicarbonate, fluoride, 

silica, dissolved solids, and bromide were similar for

Description of South Skunk River Alluvial Deposits Near Newton 17
93°08'

I

41°39'-

41°38'-

Basefrom U.S. Geological Survey digital data 1:100,000,1991 

Universal Transverse Mercator projection 

Zone 15

4,000 FEET

EXPLANATION

400 800 METERS

710 Bedrock contour Shows altitude of bedrock surface. 

Contour interval 10 feet. Datum is sea level

4-^ Trace of seismic geophysical section 

A-A' through L-L1

 - Boundary between upland area and river valley 

N7-320 Observation well and identifier

Figure 4. Altitude and configuration of bedrock surface based on seismic-retraction and test-hole data, South Skunk River Valley near 

Newton, Iowa.

18 Ground Water Near Newton. Jasper County, Iowa
93°06'

41°39'-

41°38'-

Base from U.S. Geological Survey digital data 1:100,000,1991 

Universal Transverse Mercator projection 

Zone 15

EXPLANATION

I 

0 400 800 METERS

4,000 FEET

i i

 50 Line of equal thickness of unconsolidated 

deposits Interval 10 feet

 - Boundary between upland area and river valley 

N7-320 Observation well and identifier

Figure 5. Thickness of unconsolidated deposits based on seismic-refraction and test-hole data, South Skunk River Valley near Newton, 

Iowa.

Description of South Skunk River Alluvial Deposits Near Newton 19
Table 3. Static water-level measurements from observation wells, 

municipal wells, and surface-water sites in the South Skunk River 

alluvium near Newton, Iowa, February, June, and October 2000

[Water levels in feet above sea level; observation wells measured 

February 29, June 7, and October 15; municipal wells measured 

February 27, June 7, and October 15; South Skunk River measured 

March 1, June 8, and October 17]

Data-collection 

site (fig. 2) February June October

Observation wells

Nl-33

" N3-^7

N4-51

NS^tl

N6-46

N7-32

N8-45

N9-45

N10-45

Nil-42

N 12-52

N13-41

757.02

755.58

741.41

753.50

756.47

754.79

753.70

758.67

764.21

760.59

757.85

757.83

756.34

756.35

740.60

757.74

759.48

757.25

755.09

760.21

769.91

763.78

760.03

758.96

754.57

752.55

736.66

750.56

752.33

752.13

751.23

755.25

761.41

757.02

754.96

753.71

Municipal wells

Well 1

Well 3

WellS

Well 6

Well 7 ,

Well 8

Well 9

Well 10

Well 11

Well 12

Well 13

Well 14

Well 15

Well 16

Well 17

Well 18

Well 19

Well 20

Well 21

Well 22

Well 23

742.46

745.04

742.96

743.91

742.05

742.02

741.13

742.35

741.38

739.12

738.74

741.89

739.95

739.85

741.21

740.44

742.06

741.35

745.20

740.21

741.32

741.21

742.13

743.13

742.16

746.55

739.77

740.13

740.35

740.38

737.79

737.74

743.39

738.79

738.43

739.46

737.61

741.06

739.60

738.70

738.71

739.32

741.71

743.04

741.88

741.49

745.38

739.02

739.55

739.43

739.38

738.20

737.99

743.72

739.04

738.85

740.71

738.77

741.31

740.18

742.62

739.96

740.15

South Skunk River

Neptune Street

bridge

Highway 14 bridge

762.22

753.74

762.44

754.00

761.33

752.84

all samples. Samples from all observation wells 

except well Nl-33 had low concentrations of dissolved oxygen.

Measured values of pH, temperature, potassium, 

chloride, nitrite nitrogen, total phosphorus, and orthophosphorus were similar for all ground-water samples 

but higher for the river sample. River water was substantially more alkaline than ground-water samples. 

River water contained about twice as much potassium 

and chloride as ground-water samples. Grounds water 

samples typically contained ammonia plus organic 

nitrogen near or less than the method detection limit 

(0.10 mg/L), whereas the river-water sample was substantially higher (0.30 mg/L). River water also contained detectable concentrations of nitrite nitrogen, 

total phosphorus, and orthophosphorus, whereas 

ground-water samples were near or less than method 

detection limits.

Sulfate, ammonia nitrogen, nitrite plus nitrate, 

iron, and managanese concentrations varied. Sulfate 

was present in all samples, ranging from 34 to 

112 mg/L. River water contained sulfate concentrations similar to ground water in some observation 

wells. Ammonia nitrogen was detected in all samples, 

including the river-water sample, with the exception of 

two ground-water samples. Nitrite plus nitrate nitrogen was detected only in three ground-water samples 

and one river-water sample. Considering that groundwater samples contained no detectable nitrite concentrations, nitrite plus nitrate concentrations are composed primarily of nitrate nitrogen. One sample 

(well Nl-33) exceeded the U.S. Environmental Protection Agency Maximum Contaminant Level for 

nitrate (10 mg/L as N) (U.S. Environmental Protection 

Agency, 1996). Iron concentrations ranged from-less 

than 10 to 2,350 pig/L. Samples that were high in iron 

also were high in manganese. Samples that had iron 

concentrations less than the method detection 

limit were the same samples that had detectable 

nitrate nitrogen concentrations, indicating 

oxygenated conditions.

Results of the water-quality sampling indicate that 

reducing conditions are present at most of the alluvial 

ground-water sampling sites in the study area. Conditions that are indicative of a reducing environment are 

low dissolved oxygen, large concentrations of iron and 

managanese, nitrogen in the reduced forms of nitrite or 

ammonia, and potentially high sulfate concentrations. 

Samples that contained substantial amounts of dissolved oxygen contained low concentrations of iron

20 Ground Water Near Newton, Jasper County, Iowa
93°08' 93°06'

41°39-

41°38'-

South Skunk 

River at 

Neptune St.

Base from U.S. Geological Survey digital data 1:100,000,1991 

Universal Transverse Mercator projection 

Zone 15

4,000 FEET

EXPLANATION

400 800 METERS

 755 Potentiometric contour Shows altitude at which water 

level would have stood in tightly cased wells. Contour 

interval 5 feet. Datum is sea level

 ^- Approximate direction of ground-water flow

 - Boundary between upland area and river valley 

N7-32 0 Observation well and identifier 

River at Hwy 14 ^ Surface-water measurement site and identifier

Figure 6. Potentiometric surface of alluvial aquifer, South Skunk River Valley near Newton, Iowa, June 6,2000.

Description of South Skunk River Alluvial Deposits Near Newton 21
Table 4. Selected water-quality characteristics and constituents in water from selected wells in the South Skunk River alluvial aquifer and So

Ground WaterNear Newtoi

Sr 

45CD

n

o

a

5" 

I

[mg/L, milligrams per liter; nS/cm, microsiemens per centimeter at 25 degrees Celsius; °C, degrees Celsius; (ig/L, micrograms per liter; --, no data available; <

Data-collection 

site 

(fig. 2)

Nl-33

N4-51

N5-41

N6-46

N7-32 

N8-45

N9^5

N10-45

Nil-42

N 12-52

N13-41

South Skunk

River at

Highway 14

Newton

municipal

well 13

Site identification

413938093071601 

413856093073201

413907093064401 

413828093054701

413753093054701

413831093062201 

413802093062201

413940093084601

413854093090101

413840093081101

413749093065901

413723093054701

05471380

413913093070001

-Date 

(month/day/ 

year)

6/7/2000 

6/6/2000

6/6/2000 

6/8/2000

6/8/2000

6/8/2000 

6/8/2000

6/7/2000

6/7/2000

6/7/2000

6/7/2000

6/7/2000

tf/8/2000

7/19/2000

Time 

(24 hour)

1330 

1400

1600 

1945

2030

1445 

1700

0845

1030

1715

1515

1330

1230

1400

Oxygen, 

dissolved 

(mg/L)

8.0 

.1

.1

.3

~

.2 

.2

.1

.1

.1

.2

.2

9.3

--

pH, water, 

whole, onsite 

(standard units)

6.7 

6.7

6.7 

6.8

7.1

7.2 

6.8

7.0

7.0

6.8

6.8

6.8

8.2

6.9

Specific 

conductance 

(US/cm)

750 

593

884 

819

747

524 

555

793

896

540

688

633

640

673

Temperature 

water

13.0 

12.0

13.2 

16.0

16.6

15.0 

13.0

12.5

12.5

12.1

12.5

13.0

23.5

12.2

Alkalinity, 

(mg/L as C

254 

200

415 

330

212

209

228

292

352

233

292

261

242

280
Table 4. Selected water-quality characteristics and constituents in water from selected wells in the South Skunk River alluvial aquifer and Sout

2000 Continued

Data-collection 

site 

(fig. 2)

Nl-33

N3-47

N4-51

N5-41

N6-46

N7-32

N8^5

N9-45

N 10-45

Nil-42

N 12-52

N13-41

South Skunk

River at

Highway 14

Newton

municipal

well 13

Date 

(month/day/ 

year)

6/7/2000

6/6/2000

6/6/2000

6/8/2000

6/8/2000

6/8/2000

6/8/2000

6/7/2000

6/7/2000

6/7/2000

6/7/2000

6/7/2000

6/8/2000

7/19/2000

Potassium, 

dissolved 

(mg/L)

0.9

1.3

1.0

.8

1.0

.9

.9

1.4

.9

.9

1.1

1.2

2.5

1.1

Sodium, 

dissolved 

(mg/L as Na)

8.3

10

11

5.7

7.5

7.0

6.9

7.5

14

6.3

7.3

9.0

13

7.6

Bicarbonate 

(mg/L as HC03)

310

244

506

403

259

255

278

356

430

284

356

318

295

--

Carbonate 

(mg/L as C03)

0

0

0

0

0

0

0

0

0

0

0

0

0

" 

Chloride, 

dissolved 

(mg/L as Cl)

12

15

8.6

15

13

8.4

8.3

17

17

6.2

12

8.9

24

17

Fluoride, 

dissolved 

(mg/L as F)

0.4

.3

.3

.2

.3

.3

.3

.2

.2

.3

.2

.3

.3

.3

Silica

dissolv

(mg/L as 

20

20

21

24

23

23

24

22

23

21

19

26

20

23

a
Table 4. Selected water-quality characteristics and constituents in water from selected wells in the South Skunk River alluvial aquifer and So

Ground WaterNea

2

CD

O

Sr 

43

CD

r>

o

I

5"

i

2000 Continued

Data-collection 

site 

(fig. 2)

Nl-33

N3-47

N4-51

N5-41

N6-^6

N7-32

N8-45

N9^5

N10-45 .

Nil-42

N 12-52

N13^tl

South Skunk

River at

Highway 14

Newton

municipal

well 13

Date 

(month/day/ 

year)

6/7/2000

6/6/2000

6/6/2000

6/8/2000

6/8/2000

6/8/2000

6/8/2000

6/7/2000

6/7/2000

6/7/2000

6/7/2000

6/7/2000

6/8/2000

7/19/2000

Nitrogen, 

ammonia, 

dissolved 

(mg/L as N)

<0.02

.23

.03

.03

<.02

.04

.10

.02

.07

.06

.02

.12

.04

<.10

Nitrogen, nitrite 

plus nitrate, 

dissolved 

(mg/L as N)

12

<.05

<.05

.11

.20

<.05

<.05

<.05

<.05

<.05

<.05

<.05

6.6

7.8

Nitrogen, 

nitrite, Phosphorus, Phosphorus, 

dissolved dissolved ortho, dissolved 

(mg/L as N) (mg/L as P) (mg/L as P)

<0.01 <0.05 <0.01

<.01 <.05 .02

<.01 <.05 <.01

<.01 E.04 .04

<.01 <.05 <.01

<.01 <.05 .01

<.01 <.05 .05

<.01 <.05 <.01

<.01 <.05 <.01

<.01 <.05 <.01

<.01 <.05 <.01

<.01 <.05 .06

.03 .21 .19

.10

Solids, residue at 

180 °C, dissolved 

(mg/L)

454

364

543

521

309

334

350

507

577

333

419

402

418

410

Brom

disso

(mg/L 

0.

.

.

.

.

.

.

.

.

.

.

.

.
and manganese and large amounts of nitrate nitrogen. 

Water quality for city of Newton municipal well 13, 

sampled as part of a separate program, is also listed in 

table 4 for comparison purposes.

The cause of low dissolved-oxygen concentrations 

and the reducing conditions in the aquifer is not 

known. One explanation would be that the alluvial valley could be a regional discharge area for groundwater flow that upwells from bedrock into the alluvial 

materials. This discharge of deep, regional ground 

water would be expected to contain "old" water with 

little to no remaining dissolved oxygen. Norton and 

others (1912) report that wells drilled into the Mississippian aquifer beneath the South Skunk River Valley 

are artesian, with hydraulic heads from 10 to 20 ft 

above the valley land surface. Wells drilled to the bedrock beneath the alluvial aquifer or additional alluvial 

wells at various depths would need to be installed to 

verify upward ground-water gradients tyeneath the valley and to confirm a discharge area of bedrock water.

A second explanation of the reducing conditions 

could be a biochemically driven reaction that is causing the denitrification of nitrate nitrogen with depth in 

the aquifer. The land use throughout and upgradient of 

th§ study area is mainly row-crop agriculture that utilizes substantial inputs of nitrogen fertilizer. As this 

nitrogen, predominately in the form of nitrate, infiltrates deeper in the aquifer, micro-organisms utilize 

the nitrate as part of their metabolism. These metabolic reactions result in reduced forms of nitrogen and 

low concentrations of dissolved oxygen. The low dissolved oxygen then causes oxidized forms of iron and 

manganese naturally present in the geologic materials 

to become reduced and mobilize into the dissolved 

phase. A source of organic carbon is needed to support 

these types of biochemical reactions. Well logs that 

describe coal, wood, and other buried vegetation indicate the presence of carbon in the aquifer to support 

these types of reactions.

GROUND-WATER SOURCES IN THE JASPER 

COUNTY AREA

Hydrogeologic units underlying the Jasper County 

area (table 1) vary considerably in lithology, 

thickness, extent, and water-yielding capability. The 

primary ground-water sources are alluvial aquifers, 

glacial-drift aquifers, buried-channel aquifers, and 

bedrock aquifers.

The rate at which ground water can be withdrawn 

from wells in Jasper County is not only different for 

each aquifer but also can be different within each aquifer depending on location and local aquifer characteristics. Generally, the thicker the aquifer, the more 

water it will yield to a well. Alluvial aquifers will 

yield more water to wells on a sustained basis where 

the deposits are exposed at or near the surface and can 

be recharged by infiltrating precipitation or by surface 

water. Glacial-drift and buried-channel aquifersxan 

have moderately high yields, but usually cannot sustain high pumping rates (greater than 300 gal/min) 

because recharge to these deeper aquifers is limited 

by the water-transmitting characteristics of the 

overlying materials.

In areas where carbonate (limestone and dolomite) 

bedrock is near the land surface and is not covered by 

confining units, the rock may be highly fractured due 

to weathering and erosion prior to burial by youngeraged materials. Fractures in bedrock aquifers improve 

water-transmitting characteristics to wells.

In addition to well yield, water quality also affects 

whether ground water is used for human consumption. 

Naturally occurring minerals, such as dissolved solids 

and sulfate, limit the use of ground water in some 

areas either because of drinking-water regulations or 

for aesthetic reasons.

The aquifers that can consistently produce yields 

of sufficient quantity and that have acceptable water 

quality for municipal water supply in Jasper County 

include alluvial aquifers, the Mississippian aquifer, 

and the St. Peter and Jordan aquifers of the CambrianOrdovician aquifer system. Water from glacial-drift 

and buried-channel aquifers is used mainly by private, 

rural wells.

Alluvial Aquifers

Alluvial aquifers are the shallowest, and therefore 

most readily available, source of potential groundwater supply. Alluvial aquifers in Jasper County are 

composed of stream-deposited unconsolidated materials (mostly sand, gravel, silt, and clay) that occur in 

river valleys. Sand and gravel are the most permeable 

of the alluvial materials.

Two principal alluvial aquifers occur in Jasper 

County one along the South Skunk River and the 

other along the North Skunk River (Bruner and Hallberg, 1987). The lithology and thickness of the South 

Skunk River alluvial deposits near Newton are

Ground-Water Sources in the Jasper County Area 25
described in the previous section of this report. Other 

smaller alluvial aquifers occur along Indian Creek and 

Elk Creek (Twenter and Coble, 1965).

Lithology and thickness of the alluvial aquifer in 

the South Skunk River Valley upstream and downstream from the study area is mostly unknown except 

from drillers' logs at a few well locations. That limited 

information does not indicate the presence of thicker 

alluvial deposits than those near the Newton well field. 

Information .on alluvial materials along the North 

Skunk River, Indian Creek, and other streams in Jasper 

County is also limited. Alluvial materials along these 

smaller streams are probably thinner than those in the 

South Skunk River Valley and would have smaller 

water-yielding capabilities, except in locations 

where the alluvial aquifer might overlie a buriedchannel aquifer.

Twenter and Coble (1965) report yields from 

the South Skunk River alluvium to be greater than 

500 gal/min. A well in the Newton well field was 

pumped at a rate of 950 gal/min as part of an aquifer 

test ((Layne-Western Company, Inc., written commun., 1970). The greatest saturated thickness of sand 

and gravel in other alluvial aquifers (possibly as much 

as about 50 ft, locally) could produce yields of a few 

hundred gallons per minute to individual largediameter wells.

The water quality of the alluvial aquifers reflect 

the characteristics of water from wells that are completed in sand and gravel consisting mostly of siliceous materials of low solubility. Majors ions are 

calcium and bicarbonate, but sulfate and sodium are 

also important constituents. Hardness averages about 

400 mg/L (CaCO3 ), and alkalinity averages about 

250 mg/L (CaCO3 ). Concentrations of dissolved solids averaging about 500 mg/L are characteristic of 

water from alluvial aquifers in the South Skunk River 

Valley (Twenter and Coble, 1965).

Glacial-Drift and Buried-Channel Aquifers

Glacial-drift aquifers are composed of materials 

very similar to alluvial aquifer materials. The glacialdrift aquifers contain thin to moderately thick lenses of 

aquifer material that tend to be discontinuous and produce variable yields to wells. Glacial-drift and the possibility of aquifer material can be found over much of 

the upland area. Norton and others (1912) report that 

wells completed in loess and glacial drift in upland 

areas of Jasper County produce acceptable quantities

and quality for private wells. These wells range from 

25 to 300 ft deep.

Ground water from the glacial-drift aquifers is of 

generally acceptable quality, but wells seldom yield 

large quantities of water except locally from thick layers of sand and gravel that may be present above the 

contact between the glacial drift and bedrock. Adequate information is not available to define the 

specific characteristics of these sources. Major ions 

are calcium and bicarbonate, but like the alluvial 

aquifers, sodium and sulfate are also common ions. 

Hardness averages about 375 mg/L (CaCO3 ), and dissolved solids average about 450 mg/L (Twenter and 

Coble, 1965).

Buried-channel aquifers are composed of alluvial 

materials deposited in bedrock valleys that have been 

covered by glacial deposits. Buried-channel aquifers 

can, but do not always, coincide with present stream 

valleys. Buried-channel deposits are difficult to locate 

because indications at the land surface normally are 

lacking (Olcott, 1992). Two major bedrock valleys 

were mapped by Hansen (1985) in Jasper County. One 

bedrock valley extends from east to west across the 

northern one-half of the county, whereas the other bedrock valley extends from east to west across the southern part of the county before turning northwesterly in 

the western part of the county. The thickness and type 

of materials filling these bedrock valleys and their 

water-yielding characteristics are not well known.

Ground water from buried-channel aquifers in 

central Iowa is generally more highly mineralized 

than water from the alluvial or glacial-drift aquifers. 

Major ions are calcium and bicarbonate, hardness 

averages about 1,200 mg/L (CaCO3 ), and dissolved 

solids average about 2,000 mg/L (CaCO3 ) (Twenter 

and Coble, 1965).

Bedrock Aquifers

Some bedrock units are sources of water, and 

some yield very little water. The bedrock units that 

yield water to wells are, in order of increasing depth 

below land surface, the Mississippian aquifer, the 

Silurian-Devonian aquifer, and the CambrianOrdovician aquifer system.

Bedrock of Pennsylvanian age discontinuously 

underlies surficial unconsolidated materials and 

consists primarily of shale, thin layers of sandstone, 

siltstone, coal, and possibly limestone. These rocks 

form a regional confining unit that in some areas

26 Ground Water Near Newton, Jasper County. Iowa
separate overlying unconsolidated materials from the 

Mississippian aquifer. In some localized areas, a limited water supply can be developed in bedrock of 

Pennsylvanian age.

The natural chemical quality of water from the 

principal bedrock aquifers in Jasper County is highly 

variable. The chemical quality of ground water is 

affected primarily by the mineralogy of aquifer materials and the length of time that the water is in contact 

with these minerals (Olcott, 1992). Because concentrations increase along flow paths, ground water in 

outcrop and recharge areas is the least mineralized. 

Ground water in deep, confined aquifers where the 

water movement is slow tends to be the most 

mineralized.

The Mississippian aquifer is composed primarily 

of limestone and dolomite but can contain shale or 

evaporite deposits. The thickness of the Mississippian 

aquifer ranges from about 100 to more than 300 ft in 

Jasper County, and well yields typically range from 

20 to 50 gal/min (Twenter and Coble, 1965).

The quality of water from the Mississippian aquifer is highly variable, but the water generally is quite 

mineralized. Water from the Mississippian aquifer 

tends to be of the calcium bicarbonate type. The dissolved-solids concentrations can range from 2,000 to 

3,000 mg/L (Olcott, 1992).

The Silurian-Devonian aquifer is separated from 

the overlying Mississippian aquifer by a thick, usually 

shale, confining unit. Although composed primarily of 

carbonate rocks (limestone and dolomite), the Silurian-Devonian aquifer may contain evaporite minerals, such as gypsum and anhydrite. Typical thickness 

of the Silurian- Devonian aquifer in Jasper County is 

about 600 ft (Twenter and Coble, 1965). Well yields of 

less than 20 gal/min are estimated for most of Jasper 

County except near the western boundary of the 

county where yields increase to 20-50 gal/min 

(Twenter and Coble, 1965).

Evaporite deposits that occur locally in the 

Silurian-Devonian aquifer have a major effect on 

water quality. In areas where these minerals occur, 

degradation of water quality can be caused by high 

concentrations of sulfate, sodium, potassium, and 

chloride. Dissolved-solids concentrations in the Silurian-Devonian aquifer are in excess of 5,000 mg/L 

throughout most of Jasper County (Olcott, 1992). This 

naturally occurring poor water quality limits the use of 

water from the Silurian-Devonian aquifer.

The Cambrian-Ordovician aquifer system is a 

complex multi-aquifer system with individual aquifers 

separated by leaky confining units. In Iowa, the system 

is separated by a thick confining unit into an upper 

part, the Cambrian-Ordovician aquifer, and a lower 

part, the Dresbach aquifer (Olcott, 1992). The 

Cambrian-Ordovician aquifer system contains the 

deepest water-bearing units in Jasper County (Olcott, 

1992). Sandstone in the upper part occurs from about 

700 to 900 ft below land surface (Twenter and Coble, 

1965). The Dresbach aquifer contains saline water 

throughout most of Iowa and is not used extensively. 

Rocks in the lower part of the Cambrian-Ordovician 

aquifer system are not considered aquifers in central 

Iowa, so only aquifers in the upper part of the Cambrian-Ordovician aquifer system will be discussed.

The Cambrian-Ordovician aquifer, also referred to 

as the St. Peter-Prairie du Chien-Jordan aquifer, contains two sandstone aquifers, the St. Peter aquifer and 

the Jordan aquifer, separated by a unit composed predominately of dolomite, and is about 550 ft thick in 

Jasper County (Twenter and Coble, 1965). In some 

parts of Iowa, the three units generally are hydraulically connected due to fracturing in the dolomite and 

function as one aquifer. The Jordan aquifer, ranging 

in thickness from 40 to 60 ft, yields more than 

1,000 gal/min throughout Jasper County (Twenter and 

Coble, 1965). Ground-water flow in the CambrianOrdovician aquifer is generally southeasterly (Olcott, 

1992). Primary recharge to the Cambrian-Ordovician 

aquifer is from vertical leakage (Burkart and Buchmiller, 1990). Declining water levels in this aquifer in 

some parts of Iowa are attributed to regional pumping 

rates exceeding recharge (Burkart and Buchmiller, 

1990).

The water from the Cambrian-Ordovician aquifer 

is not as highly mineralized as that from parts of the 

Mississippian and Silurian-Devonian aquifers. Water 

from this aquifer generally is a calcium bicarbonate 

type and has hardness of about 300 mg/L (CaCO3), 

and dissolved-solids concentrations range from 500 to 

1,000 mg/L (Twenter and Coble, 1965). Large concentrations of iron, fluoride, and radium (Ra-266) (Horick 

and Steinhilber, 1978) are possible in water from this 

aquifer at some locations.

SUMMARY

The city of Newton obtains its municipal water 

supply from the South Skunk River alluvial aquifer.

Summary 27
Withdrawals averaged 4.5 Mgal/d in 1998, and additional sources of water may be needed by the city to 

meet an expected demand of 8 Mgal/d by 2007.

To help address concerns about future sources of 

water supply, the U.S. Geological Survey, in cooperation with city of Newton, conducted a study to provide 

information about the sources of ground water (unconsolidated and bedrock aquifers) in Jasper County, particularly near the Newton area.

Available hydrologic and geologic information 

was compiled from the scientific literature and previous studies in the Newton area. Additional thickness 

and lithologic data for the unconsolidated materials in 

the South Skunk River Valley were collected for this 

study at selected sites from October 1999 through 

October 2000. Information on river stage and water 

quality in the South Skunk River alluvial aquifer near 

Newton also was collected.

The alluvial deposits along the South Skunk River 

Valley near Newton consist of sand and gravel deposits of glacial and fluvial origin. The sand and gravel 

are commonly interbedded with clay and silt lenses in 

the upper 20 ft of the deposits. Deeper materials 

appear to be primarily sand and gravel. The upper 

bedrock beneath the alluvial aquifer consists of shale 

or limestone.

Seismic refraction and test-hole drilling were used 

to collect geologic information for the unconsolidated 

material in the South Skunk River Valley. Seismic 

refraction was used to determine the depth to bedrock 

below land surface and to estimate the thickness of 

unconsolidated materials. Test holes were drilled to 

determine the thickness and lithology of the unconsolidated material and to construct observation wells for 

measuring water levels and collecting waterquality samples.

Thicknesses of the unconsolidated materials in the 

South Skunk River Valley in the study area range 

from less than 30 to more than 60 ft. Unconsolidated 

materials in three areas appear to exceed 50 ft in thickness an area about 5,000 ft west of the present well 

field, the present well field area, and an area about 

5,000 ft southeast of the present well field.

Water levels measured during 2000 indicate 

ground-water movement towards the Newton well 

field from within the alluvial aquifer. Water levels in 

the alluvial aquifer on the well-field side of the South 

Skunk River were lower than water levels in the river, 

indicating flow from the river toward the well field.

Water quality in the aquifer was similar to water 

quality in the South Skunk River except that most 

ground-water samples were low in dissolved oxygen. 

The reducing conditions in the aquifer resulted in high 

concentrations of iron and manganese and reduced 

forms of nitrogen.

REFERENCES

Bruner, D.R., and Hallberg, G.R., 1987, An overview of 

ground water quality in the Skunk River Basin: Iowa 

Department of Natural Resources-Geological Survey 

Bureau Open-File Report 87-3, 36 p.

Burkart, M.R., and Buchmiller, R.C., 1990, Regional evaluation of hydrologic factors and effects of pumping, St. 

Peter-Jordan aquifer, Iowa: U.S. Geological Survey 

Water-Resources Investigations Report 90-4009,44 p.

Haeni, P.P., 1988, Application of seismic-refraction techniques to hydrologic studies: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 2, 

chap. D2, 86 p.

Hansen, R.E., 1985, Bedrock topography of central Iowa: 

U.S. Geological Survey Miscellaneous Investigations 

Map 1-1609,2 sheets, scale 1:125,000.

Horick, P.J., 1984, Silurian-Devonian aquifer of Iowa: Iowa 

Geological Survey Miscellaneous Map Series No.. 10, 

4 sheets, scale 1:1,000,000.

Horick, P.J., and Steinhilber, W.L., 1973, Mississippian 

aquifer of Iowa: Iowa Geological Survey Miscellaneous Map Series No. 3, 3 sheets, scale 1:1,000,000.

 1978, Jordan aquifer of Iowa: Iowa Geological Survey Miscellaneous Map Series No. 6, 3 sheets, 

scale 1:1,000,000.

Nalley, G.M., German, J.G., Goodrich, R.D., Miller, V.E., 

Turco, M.J., and Linhart, S.M., 2001, Water resources 

data, Iowa, water year 2000: U.S. Geological Survey 

Water-Data Report IA-00-1, v. 1, 346 p.

Norton, W.H., Hendrixson, W.S., Simpson, H.E., and Meinzer O.E., 1912, Underground water resources of Iowa: 

U.S. Geological Survey Water-Supply Paper 293, 

p. 596-609:

Olcott, P,G, 1992, Ground water atlas of the United States, 

segment 9: U.S. Geological Survey Hydrologic Investigations Atlas 730-J, 31 p.

Prior, J.C., 1991, Landforms of Iowa: Iowa City, University 

of Iowa Press, 153 p.

Rimrock Geophysics, Inc., 1995, SIPT2V4.2, Seismic 

refraction interpretation programs: Lakewood, 

Colorado, Rimrock Geophysics, Inc., 56 p.

Twenter, F.R., and Coble, R.W., 1965, The water story in 

central Iowa: Iowa Geological Survey Water Atlas 

Number 1, 89 p.

U.S. Environmental Protection Agency, 1996, Drinking 

water regulations and health advisories: Washington 

D.C., Report 822-R-96-001, 16 p.

Williams, I.A., 1904, Geology of Jasper County: Iowa Geological Survey, v. XV, Annual Report, p. 277-367.

28 Ground Water Near Newton, Jasper County, Iowa
Robert C. Buchmiller GROUND WATER NEAR NEWTON, JASPER COUNTY. IOWA USGS/WRIR 01