Hydrogeology of Shallow Basin-Fill

Deposits in Areas of Salt Lake Valley,

Salt Lake County, Utah

Water-Resources Investigations Report 03–4029

U.S. Department of the Interior

U.S. Geological Survey

National Water-Quality Assessment Program

Hydrogeology of Shallow Basin-Fill Deposits in 

Areas of Salt Lake Valley, Salt Lake County, Utah

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

By Susan A. Thiros

Salt Lake City, Utah

2003

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 03-4029
U.S. DEPARTMENT OF THE INTERIOR

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

U.S. Geological Survey

Branch of Information Services

Box 25286, Denver Federal Center

Denver, CO 80225-0286

1-888-ASK-USGS

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.

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

District Chief

U.S. Geological Survey

2329 Orton Circle

Salt Lake City, Utah 84119

http://ut.water.usgs.gov
 iii

FOREWORD

The U.S. Geological Survey (USGS) is committed to serve the Nation with accurate and timely scientific 

information that helps enhance and protect the overall quality of life, and facilitates effective management of water, 

biological, energy, and mineral resources (http://www.usgs.gov/). Information on the quality of the Nation’s water 

resources is of critical interest to the USGS because it is so integrally linked to the long-term availability of water 

that is clean and safe for drinking and recreation and that is suitable for industry, irrigation, and habitat for fish and 

wildlife. Escalating population growth and increasing demands for the multiple water uses make water availability, 

now measured in terms of quantity and quality, even more critical to the long-term sustainability of our 

communities and ecosystems.

The USGS implemented the National Water-Quality Assessment (NAWQA) program to support national, 

regional, and local information needs and decisions related to water-quality management and policy 

(http://water.usgs.gov/nawqa). Shaped by and coordinated with ongoing efforts of other Federal, State, and local 

agencies, the NAWQA program is designed to answer: What is the condition of our Nation’s streams and ground 

water? How are the conditions changing over time? How do natural features and human activities affect the quality 

of streams and ground water, and where are those effects most pronounced? By combining information on water 

chemistry, physical characteristics, stream habitat, and aquatic life, the NAWQA program aims to provide sciencebased insights for current and emerging water issues and priorities. NAWQA results can contribute to informed 

decisions that result in practical and effective water-resource management and strategies that protect and restore 

water quality.

Since 1991, the NAWQA program has implemented interdisciplinary assessments in more than 50 of the 

Nation’s most important river basins and aquifers, referred to as Study Units (http://water.usgs.gov/nawqa/ 

nawqamap.html). Collectively, these Study Units account for more than 60 percent of the overall water use and 

population served by public water supply, and are representative of the Nation’s major hydrologic landscapes, 

priority ecological resources, and agricultural, urban, and natural sources of contamination. 

Each assessment is guided by a nationally consistent study design and methods of sampling and analysis. 

The assessments thereby build local knowledge about water-quality issues and trends in a particular stream or 

aquifer while providing an understanding of how and why water quality varies regionally and nationally. The 

consistent, multi-scale approach helps to determine if certain types of water-quality issues are isolated or pervasive, 

and allows direct comparisons of how human activities and natural processes affect water quality and ecological 

health in the Nation’s diverse geographic and environmental settings. Comprehensive assessments on pesticides, 

nutrients, volatile organic compounds, trace metals, and aquatic ecology are developed at the national scale through 

comparative analysis of the Study-Unit findings (http://water.usgs.gov/nawqa/natsyn.html). 

The USGS places high value on the communication and dissemination of credible, timely, and relevant 

science so that the most recent and available knowledge about water resources can be applied in management and 

policy decisions. We hope this NAWQA publication will provide you the needed insights and information to meet 

your needs, and thereby foster increased awareness and involvement in the protection and restoration of our 

Nation’s waters. 

The NAWQA program recognizes that a national assessment by a single program cannot address all waterresource issues of interest. External coordination at all levels is critical for a fully integrated understanding of 

watersheds and for cost-effective management, regulation, and conservation of our Nation’s water resources. The 

program, therefore, depends extensively on the advice, cooperation, and information from other Federal, State, 

interstate, Tribal, and local agencies, non-government organizations, industry, academia, and other stakeholder 

groups. The assistance and suggestions of all are greatly appreciated.

Robert M. Hirsch

Associate Director for Water
 v

CONTENTS

Foreword .............................................................................................................................................................. iii

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

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

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

Hydrogeologic Setting ................................................................................................................................ 2

Methods....................................................................................................................................................... 5

Lithologic and Borehole Geophysical Logs....................................................................................... 8

Hydraulic Conductivity and Transmissivity ...................................................................................... 9

Water-Level and Temperature Fluctuations ...................................................................................... 10

Hydrogeology of Shallow Basin-Fill Deposits .................................................................................................... 10

Lithologic and Borehole Geophysical Logs................................................................................................ 10

Hydraulic Conductivity and Transmissivity ............................................................................................... 11

Water-Level and Temperature Fluctuations................................................................................................ 12

Water-Level Gradients ................................................................................................................................ 19

Summary .............................................................................................................................................................. 22

References Cited .................................................................................................................................................. 22
vi 

FIGURES

Figure 1. Map showing location and geographic features of Salt Lake Valley, Utah....................................... 3

Figure 2. Generalized block diagram showing the basin-fill deposits and ground-water flow system in 

Salt Lake Valley, Utah....................................................................................................................... 4

Figure 3. Map showing location of monitoring wells installed in recently developed residential/

commercial areas of Salt Lake Valley, Utah ..................................................................................... 6

Figure 4. Photographs of cores of basin-fill deposits from two monitoring wells in Salt Lake Valley, Utah .. 9

Figure 5. Map showing distribution of hydraulic-conductivity and transmissivity values determined 

from slug tests done at selected monitoring wells in Salt Lake Valley, Utah ................................... 14

Figure 6. Map showing water-level surface for the shallow ground-water system, Salt Lake Valley, Utah, 

March 2000 ........................................................................................................................................ 15

Figure 7. Graph showing water level and water temperature measured in monitoring well 26D and 

discharge determined for Little Cottonwood Creek at gaging station 10167800, Salt Lake 

Valley, Utah, 2000-2001.................................................................................................................... 16

Figure 8. Graphs showing relation between water level and water temperature in selected monitoring 

wells in Salt Lake Valley, Utah ......................................................................................................... 17

Figure 9. Graphs showing water-level and water-temperature fluctuations measured in monitoring 

wells 2, 22, and 29, Salt Lake Valley, Utah....................................................................................... 18

Figure 10. Map showing direction of vertical water-level gradient and the difference between water 

levels in the shallow ground-water system and the deeper aquifer in Salt Lake Valley, Utah.......... 20

Figure 11. Hydrograph showing water levels measured in two monitoring wells near Kearns, Utah................ 21

[Plate is in pocket]

Plate 1. Map showing location; logs showing lithology, natural gamma radiation count, and electrical 

conductivity of the basin-fill deposits; and hydrographs showing water-level fluctuations from 

September 1999 to July 2001 for monitoring wells installed in recently developed residential/

commercial areas, Salt Lake Valley, Utah
 vii

TABLES

Table 1. Description, lithology, and water level for monitoring wells drilled in Salt Lake Valley, Utah, 

1999 ................................................................................................................................................... 7

Table 2. Specific-capacity and slug-test data for 20 monitoring wells in Salt Lake Valley, Utah .................. 13
viii Conversion Factors and Datums

CONVERSION FACTORS AND DATUMS

1Expresses transmissivity. An alternative way of expressing transmissivity is cubic foot per day per square 

foot, times foot of aquifer thickness [(ft3/d)ft2]ft.

Specific conductance is reported in microsiemens per centimeter at 25 degrees Celsius (μS/cm).

Natural gamma radiation is reported in gamma counts per second and electromagnetic induction is 

reported in micromhos per meter.

Vertical coordinate information is referenced to the North American Vertical Datum of 1929 (NAVD 

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

Multiply By To obtain

acre-foot per year (acre-ft/yr) 1,233 cubic meter per year

cubic foot per second (ft3/s) 0.02832 cubic meter per second

cubic foot per second per mile (ft3/s/mi) 0.01760 cubic meter per second per kilometer

foot (ft) 0.3048 meter

foot per day (ft/d) 0.3048 meter per day

foot squared per day 1(ft2/d) 0.0929 meter squared per day

gallon per minute per foot (gal/min/ft) 12.419 liter per minute per foot

inch (in.) 25.4 millimeter

mile (mi) 1.609 kilometer

Water temperature is reported in degrees Celsius (oC), which can be converted to degrees Fahrenheit (oF) 

by the following equation: oF = 1.8(oC) + 32.
Abstract 1

Hydrogeology of Shallow Basin-fill Deposits In 

Areas of Salt Lake Valley, Salt Lake County, Utah

By Susan A. Thiros

ABSTRACT

A study of recently developed 

residential/commercial areas of Salt Lake Valley, 

Utah, was done from 1999 to 2001 in areas in 

which shallow ground water has the potential to 

move to a deeper aquifer that is used for public 

supply. Thirty monitoring wells were drilled and 

sampled in 1999 as part of the study. The ground 

water was either under unconfined or confined 

conditions, depending on depth to water and the 

presence or absence of fine-grained deposits. The 

wells were completed in the shallowest waterbearing zone capable of supplying water. 

Monitoring-well depths range from 23 to 154 feet. 

Lithologic, geophysical, hydraulic-conductivity, 

transmissivity, water-level, and water-temperature 

data were obtained for or collected from the wells.

Silt and clay layers noted on lithologic logs 

correlate with increases in electrical conductivity 

and natural gamma radiation shown on many of 

the electromagnetic-induction and natural gamma 

logs. Relatively large increases in electrical 

conductivity, determined from the 

electromagnetic-induction logs, with no major 

changes in natural gamma radiation are likely 

caused by increased dissolved-solids content in the 

ground water. Some intervals with high electrical 

conductivity correspond to areas in which water 

was present during drilling.

Unconfined conditions were present at 7 of 

20 monitoring wells on the west side and at 2 of 10 

wells on the east side of Salt Lake Valley. Finegrained deposits confine the ground water. 

Anthropogenic compounds were detected in water 

sampled from most of the wells, indicating a 

connection with the land surface.

Data were collected from 20 of the 

monitoring wells to estimate the hydraulic 

conductivity and transmissivity of the shallow 

ground-water system. Hydraulic-conductivity 

values of the shallow aquifer ranged from 30 to 

540 feet per day. Transmissivity values of the 

shallow aquifer ranged from 3 to 1,070 feet 

squared per day. There is a close linear relation 

between transmissivity determined from slug-test 

analysis and transmissivity estimated from specific 

capacity.

Water-level fluctuations were measured in 

the 30 monitoring wells from 1999 to July 2001. 

Generally, water-level changes measured in wells 

on the west side of the valley followed a seasonal 

trend and wells on the east side showed less 

fluctuation or a gradual decline during the 2-year 

period. This may indicate that a larger percentage 

of recharge to the shallow ground-water system on 

the west side is from somewhat consistent 

seasonal sources, such as canals and unconsumed 

irrigation water, as compared to sources on the 

east side. Water levels measured in monitoring 

wells completed in the shallow ground-water 

system near large-capacity public-supply wells 

varied in response to ground-water withdrawals 

from the deeper confined aquifer. Water 

temperature was monitored in 23 wells. Generally, 

little or no change in water temperature was 

measured in monitoring wells with a depth to 

water greater than about 40 feet. The shallower the 

water level in the well, the greater the watertemperature change measured during the study.
2 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

Comparison of water levels measured in the 

monitoring wells and deeper wells in the same 

area indicate a downward gradient on the east side 

of the valley. Water levels in the shallow and 

deeper aquifers in the secondary recharge area on 

the west side of the valley were similar to those on 

the east side. Water levels measured in the 

monitoring wells and nearby wells completed in 

the deeper aquifer indicate that the vertical 

gradient can change with time and stresses on the 

system.

INTRODUCTION

As part of the National Water-Quality 

Assessment (NAWQA) program, the U.S. Geological 

Survey (USGS) studied the effects of human activities 

on the quality of shallow ground water in areas with 

recently developed urban land use in Salt Lake Valley, 

Utah, an urban area within the Great Salt Lake Basins 

study unit (fig. 1). Pioneers first settled Salt Lake 

Valley in 1847, and an irrigation system was developed 

soon after to grow crops in the semiarid climate. 

Agricultural and undeveloped areas in the valley were 

converted to residential and commercial uses as the 

population increased to about 850,000 in 1999 (U.S. 

Census Bureau, written commun., 2000).

The study was done from 1999 to 2001 in 

recently developed residential/commercial areas of the 

valley in which shallow ground water has the potential 

to move to a deeper aquifer that is used for public 

supply. In 1999, 30 monitoring wells were installed and 

the water sampled and analyzed for major ions, 

nutrients, trace metals, volatile organic compounds 

(VOCs), pesticides, radon, the stable isotopes of 

oxygen and hydrogen, and tritium to determine an 

approximate recharge date. The water-quality data are 

presented and discussed separately in Thiros (2003). 

Selected aquifer properties such as transmissivity and 

lithology were studied and water-level and temperature 

fluctuations were monitored. Information about the 

shallow ground-water system and its connection to the 

deeper system that provides drinking water for the 

valley can be used to better understand the entire 

ground-water system in the valley. 

Purpose and Scope

This report presents lithologic, geophysical, 

hydraulic-conductivity, transmissivity, water-level, and 

water-temperature data collected from the shallow 

ground-water system in Salt Lake Valley from 1999 to 

2001. The data were obtained for or collected from 

monitoring wells installed in recently developed 

residential/commercial areas of the valley. Lithologic 

and borehole geophysical logs of the subsurface are 

presented together to aid in the interpretation of the 

type of unconsolidated deposits penetrated. Water-level 

hydrographs show fluctuations with time caused by 

recharge to and discharge from the system in the study 

area. This information can be used with water-quality 

and land-use data to better understand the effects of 

human activities on the quality of shallow ground water 

where there is potential for movement to a deeper 

aquifer used for public supply.

Hydrogeologic Setting

Salt Lake Valley is within the Basin and Range 

physiographic province of Fenneman (1931) that is 

characterized by generally parallel, north- to northeasttrending mountain ranges separated by broad alluvial 

basins that are a result of Cenozoic-age extensional 

faulting. Topographic relief between the Wasatch 

Range and Salt Lake Valley is as much as 7,000 ft. 

The basin-fill deposits in the valley consist of 

unconsolidated to semiconsolidated Tertiary-age 

sediments overlain by unconsolidated Quaternary-age 

sediments. The less permeable Tertiary-age basin-fill 

deposits are associated with alluvial fans and volcanic 

ash. The saturated Quaternary-age basin-fill deposits 

range from less than 200 ft thick in the Kearns area and 

along the margins of the valley to more than 1,000 ft 

thick in the northern part of the valley (Hely and others, 

1971) and were deposited primarily in lacustrine and 

fluvial environments associated with Lake Bonneville 

and older lake cycles. Personius and Scott (1992) 

summarized the depositional history of Lake 

Bonneville from other sources. The water level of Lake 

Bonneville began rising about 30,000 years ago to a 

high of about 5,180 ft in altitude (Bonneville shoreline 

level) about 16,000 years ago. The lake dropped 

quickly to the Provo level at about 4,800 ft and much of 

the sediment deposited at or below the Bonneville level 

was eroded and transported to below the Provo level. 
Introduction 3

Base from U.S. Geological Survey digital line graph data,

1:100,000, 1979 and 1980

Universal Transverse Mercator projection, Zone 12 Bear

Lake

UTAH

IDAHO

WYOMING

Great

 Salt

 Lake

Utah

Lake

Salt

Lake

City

112r15'

 Great

 Salt

Lake

Tailings ponds

80

15

Approximate limit of basin-fill

deposits in Salt Lake Valley

40r30'

40r45'

111r37'30"

Salt Lake County

Jordan River

OQUIRRH MOUNTAINS

WASATCH RANGE

Great

Salt Lake

Basins

study

area

215

0 3 6 KILOMETERS

0 3 6 MILES

West

Valley

City

Salt

Lake

City

South

Jordan

West

Jordan

Murray

Sandy

Draper

Riverton

TRAVERSE

MOUNTAINS

Coon Creek

Barneys Creek

Bingham Creek

City Creek

Red

Creek

Butte

Creek

Emigration

Creek

Parleys

Creek Mill

Creek

Big Cottonwood

Creek

Little Cottonwood

Butterfield Creek

Rose

Creek

Provo Canal

Reservoir

Utah

Canal

Lake

South

Jordan

Canal

Distributing

Utah

Lake

Canal

Salt and

Canal

Draper

Irrigation

Canal

East Jordan

Canal

Jordan

Salt

Lake

and

Canal

Surplus

EXPLANATION

Fault

Approximate boundary of basin-fill

deposits in Salt Lake Valley

Figure 1. Location and geographic features of Salt Lake Valley, Utah.
4 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

Lake Bonneville was at the Provo shoreline level about 

13,500 years ago and retreated to the level of modern 

Great Salt Lake (about 4,210 ft) by about 11,000 years 

ago. The shallow ground-water system in the valley 

primarily is contained in deposits associated with Lake 

Bonneville and in overlying, more recent stream 

deposits.

A generalized model of the saturated basin-fill 

deposits in Salt Lake Valley consists of a relatively 

deep unconfined aquifer near the mountain fronts that 

becomes confined toward the center of the valley by 

layers of silt and clay (fig. 2). The deeper unconfined 

and confined aquifers are collectively known as the 

principal aquifer in the valley. The term “confining 

layer” is used even though, in some cases, the water 

level in the underlying principal aquifer is below the 

confining layer, and the water is actually unconfined. 

Overlying the confining layers is shallow ground water 

that is either localized in extent because it is perched on 

a confining layer or more laterally continuous and 

forms an aquifer.

The primary recharge area for the principal 

aquifer is near the mountain fronts where there are no 

continuous layers of fine-grained material to impede 

the downward movement of water (fig. 2). Leakage of 

shallow ground water to the principal aquifer is 

possible where a downward gradient exists and 

confining layers are thin and/or discontinuous. These 

conditions are present in the secondary recharge area. 

Areas where the water level in the principal aquifer was 

below the first major confining layer and where there is 

the potential for downward movement of ground water 

were mapped as secondary recharge areas (Anderson 

and others, 1994, p. 6). A discharge area exists where 

there is an upward hydraulic-head gradient from the 

deeper confined aquifer to the overlying shallow 

aquifer (fig. 2).

Basin-fill deposits of

Tertiary age

Great Salt

Lake

Fine-grained

deposits

Consolidated

rock

Water level

in shallow aquifer

Water level in

deeper confined aquifer

Deeper

confined

aquifer

Shallow

aquifer

Confining layer

Primary

recharge

area

Perched

water

Secondary

recharge

area

Discharge

area

EXPLANATION

Direction of ground-water movement

Deeper

unconfined

aquifer

Water level in

deeper unconfined

aquifer

Coarse-grained

deposits

Principal

aquifer

Basin-fill deposits of

Quaternary age Modified from Hely, and others, 1971

Figure 2. Generalized block diagram showing the basin-fill deposits and ground-water flow system in Salt Lake Valley, Utah.
Introduction 5

The shallow aquifer in the valley is generally 

unconfined, although in some areas the first saturated 

zone in the subsurface was present beneath a confining 

layer. The distinction between the shallow and deeper 

aquifers is not clear in some parts of the secondary 

recharge area. Many domestic and some public-supply 

wells are open to the water table in the secondary 

recharge area, which can occur at depths of about 100 

ft below land surface in some areas of the valley. 

Ground water is perched where the water level in 

the principal aquifer is below the bottom of the 

confining layer resulting in an unsaturated zone 

between the water table and the overlying confining 

layer and shallow ground water. In the southeastern 

part of the valley, extensive areas with perched ground 

water can be difficult to differentiate from the shallow 

aquifer.

Recharge to the principal aquifer in the valley is 

from infiltration of precipitation and unconsumed 

irrigation water, subsurface inflow from adjacent 

fractured consolidated rocks, and seepage from streams 

and canals. Recharge to the east side of Salt Lake 

Valley is much greater than that to the west side, 

primarily because of subsurface inflow and streamflow 

seepage from the Wasatch Range, which receives 

greater amounts of precipitation than do the mountains 

on the west side of the valley. Discharge from the 

principal aquifer is to wells, springs, seepage to the 

Jordan River and the lower reaches of its tributaries, the 

shallow aquifer, and evapotranspiration. About 317,000 

acre-ft/yr of water was added and removed in a steadystate numerical simulation of the ground-water system 

in Salt Lake Valley (Lambert, 1995, p. 37). The budget 

for the shallow part of the ground-water system is 

much smaller than that for the principal aquifer. The 

shallow system receives recharge from infiltration of 

precipitation and unconsumed irrigation water applied 

to fields, gardens, and lawns; seepage from streams and 

canals; and flow from the deeper confined aquifer in 

the discharge areas of the valley.

Shallow ground water is susceptible to 

contamination from activities related to land use 

because of its proximity to land surface. Manmade 

compounds such as VOCs and pesticides were detected 

in shallow ground water underlying residential areas 

(Thiros, 2003). The deeper unconfined aquifer in the 

primary recharge area also is vulnerable because of a 

lack of confining layers that can impede the downward 

movement of contaminated ground water. The 

movement of contaminated water from the shallow and 

deeper unconfined aquifers can degrade the water 

quality of the deeper confined aquifer in the secondary 

recharge area. The principal aquifer in Salt Lake Valley 

is used extensively for public supply (about 38 percent 

of the population uses ground water). 

Methods

Monitoring wells were installed at 30 sites in 

Salt Lake Valley (fig. 3) in accordance with NAWQA 

protocols (Lapham and others, 1995). Well sites were 

selected with a computerized, stratified, random 

selection process (Scott, 1990) after the following 

criteria were met: (1) location in a residential or 

commercial area developed from 1963 to 1994; (2) 75 

percent of a 500-meter (1,640-ft) circular buffer around 

the site contains the targeted land use; (3) a downward 

gradient exists between the shallow and deeper 

aquifers; and (4) a minimum distance of 1 kilometer 

(0.62 mi) exists between each site.

The monitoring wells were drilled with a hollowstem auger (8 5/8-in.-diameter borehole) or with airrotary methods where cobbles were assumed to be 

present (9-in.-diameter borehole). Ground water at the 

monitoring-well sites was under either unconfined or 

confined conditions, depending on the depth to water 

and the presence or absence of fine-grained deposits 

(table 1). The wells were completed in the shallowest 

water-bearing zone capable of supplying water. 

Monitoring-well depths range from 23 to 154 ft, and 

the wells were completed with 2-in.- diameter 

polyvinyl chloride casing attached to a 10-ft length of 

screen. Two wells were installed at one site and were 

completed at different depths. The shallower nested 

well was completed with a 5-ft length of screen. The 

top of the screened interval generally was about 5 ft 

below the water table or below where water was noted 

during drilling. 

The monitoring wells were constructed with 

sand between the casing and the borehole wall to about 

5 ft above the top of the screen. A 2-ft-thick layer of 

bentonite pellets in the annular space separates the sand 

pack from bentonite grout that extends to the land 

surface. The part of the aquifer that likely transmits 

water to the screened interval of a monitoring well, the 

contributing unit, was determined from the occurrence 

of fine-grained deposits in the subsurface (table 1). The 
6 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

Base from U.S. Geological Survey digital line graph data, 1:100,000, 1979 and 1980

Universal Transverse Mercator projection, Zone 12

Great

Salt

Lake

Tailings ponds

40r30'

40r45'

Jordan River

0 3 6 KILOMETERS

0 3 6 MILES

West

Valley

City

Salt

Lake

City

South

Jordan

West

Jordan

Murray

Sandy

Draper

Riverton

EXPLANATION

Area of recent residential and commercial land use

Perched aquifer—Data from Hely and others, 1971

Discharge area

Primary recharge area

Secondary recharge area

Approximate boundary of basin-fill deposits in Salt Lake Valley

Monitoring well—Number is well name in table 1

1 2

3

4

5 7 6

8 11 10

9

14

20 17

24 25

30

31 33

18

22

27 29 26S

26D

32

34

37

39

41

41

112r07'30" 111r48'

SALT LAKE COUNTY

DAVIS COUNTY

SALT LAKE COUNTY

UTAH COUNTY

Figure 3. Location of monitoring wells installed in recently developed residential/commercial areas of Salt Lake Valley, Utah.
Introduction 7

Table 1. Description, lithology, and water level for monitoring wells drilled in Salt Lake Valley, Utah, 1999

[Aquifer type: C, confined or U, unconfined; General lithology of contributing unit: SGVC, sand, gravel, and clay; SAND, sand; SDGL, sand and gravel; 

SDST, sand and silt; GRVL, gravel; STCL, silt and clay; SDCL, sand and clay; Top and bottom of contributing unit: upper and lower extent of basin-fill 

deposits that could contribute water to the monitoring well. Water level was measured in March 2000]

Well

number

(fig. 3)

Altitude

of land

surface

(feet)

Well

depth

Top of

screened

interval

Bottom of

screened

interval Aquifer

type

General

lithology of

contributing

unit

Top of

contributing

unit

Bottom of

contributing

unit

Water 

level

(feet below land surface) (feet below land surface)

1 4,308 48.5 38 48 C SGVC 40 48.5 32.77

2 4,294 38.5 28 38 C SGVC 26 38.5 19.55

3 4,371 114 103 113 C SAND 113 114 79.96

4 4,331 38.5 28 38 U SDGL 31 38.5 14.01

5 4,426 43.5 33 43 C SDGL 20 43.5 27.59

6 4,324 38.5 28 38 C SDST 26 38.5 23.46

7 4,396 43.5 33 43 C SDST 29 43.5 27.09

8 4,487 67.5 57 67 U SAND 46 67.5 63.37

9 4,312 38.5 28 38 C SDST 21 38.5 12.57

10 4,350 83.5 73 83 C GRVL 70 78 67.94

11 4,462 83.5 73 83 C SDGL 75.5 83.5 70.75

14 4,579 48.5 38 48 C STCL 30 48.5 27.97

17 4,380 38.5 28 38 C SGVC 32 38.5 17.72

18 4,411 106 95 105 C SGVC 102 106 76.85

20 4,477 92.5 82 92 U GRVL 79 92.5 84.66

22 4,538 36 25.5 35.5 C SDGL 15 26 21.61

24 4,473 124 113 123 C GRVL 106 124 81.98

25 4,414 68.5 58 68 C GRVL 34 68.5 49.67

26D 4,591 77.5 62 72 C SAND 0 69 32.77

26S 4,591 31.5 26 31 U SAND 0 31.5 30.43

27 4,499 73.5 63 73 C SDGL 43.5 68 58.69

29 4,532 34 23.5 33.5 C SAND 21 34 9.02

30 4,455 68.5 58 68 U SGVC 62 68.5 58.12

31 4,562 154 143 153 U SDGL 143 154 143.19

32 4,640 88.5 78 88 U SAND 0 83 76.18

33 4,466 95.5 85 95 U SDGL 66 95.5 74.14

34 4,486 77.5 67 77 C SAND 65 78.5 57.81

35 4,540 106 95 105 U GRVL 96 103 dry

37 4,725 73 62.5 72.5 C SDCL 59 69 45.18

39 4,758 106 95.5 106 U SDCL 21 105 94.02

41 4,550 23 12.5 22.5 U SDGL 0 20 5.48
8 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

contributing unit to a well could extend to land surface 

if few or no fine-grained deposits are present above the 

screened interval. 

Information about the basin-fill deposits and 

water in the subsurface was collected from these 

monitoring wells to better understand the shallow 

ground-water system in the valley. The types of data 

collected and the methods used to analyze these data 

are described in the following sections.

Lithologic and Borehole Geophysical Logs

A description of the lithology was logged while 

augering or drilling each well. The amount of 

resistance, the smoothness or roughness at the drill bit, 

and the type of drill cuttings (basin-fill deposits) 

returned to the surface provided information about the 

material in the subsurface. Cores were collected from 

some holes to get a relatively undisturbed sample from 

a known depth (fig. 4). Core samples could not be 

collected from intervals containing large gravel or 

cobbles. The occurrence and depth of water in the 

subsurface was monitored during drilling. The depth to 

water in the well after it had reached equilibrium with 

the aquifer also was measured. This information was 

compiled into a lithologic log for the well. 

Data were collected from selected completed 

monitoring wells by using borehole geophysical 

techniques to better define aquifer properties. Natural 

gamma radiation and electromagnetic induction were 

logged from near the land surface to near the bottom of 

the well. Both tools used a sample interval of 0.1 ft. 

Natural gamma radiation units were gamma counts per 

second and electromagnetic induction units were 

micromhos per meter. A natural gamma log can be 

used in stratigraphic correlation and to delineate 

changes in lithology by recording the amount of natural 

gamma radiation emitted from the unconsolidated 

deposits surrounding the borehole. In general, natural 

gamma radiation is relatively high in fine-grained 

deposits that contain abundant clay minerals and 

relatively low in coarse-grained sand and gravel 

composed mainly of quartz. Natural gamma radiation 

typically correlates inversely with hydraulic 

conductivity, a measure of how quickly water can move 

through a porous material. A change in water quality 

does not cause a change in natural gamma radiation. 

Natural gamma radiation was recorded as the number 

of counts per second per sample interval.

The most significant naturally occurring sources 

of gamma radiation are potassium-40 and daughter 

products of the uranium- and thorium-decay series (U238 and Th-232). Clay minerals commonly emit 

relatively high gamma radiation because they include 

weathering products of potassium feldspar and mica 

and tend to concentrate uranium and thorium by 

adsorption and ion exchange. Under most conditions, 

90 percent of the gamma radiation detected probably 

originates from material within 6 to 12 in. of the 

borehole wall (Keys, 1990). The borehole diameter for 

the monitoring wells was a minimum of about 9 in. (the 

diameter of the drill bit) and could be larger depending 

on the cohesiveness of the surrounding aquifer 

material. Pellets and chips made from bentonite clay 

were used to seal the space around the 2-in.-diameter 

well casing from material just below land surface and 

to separate the sand-packed interval around the well 

screen from the rest of the well (pl. 1). The bentonite 

pellets and chips caused high natural gamma-radiation 

levels; therefore, the intervals where they were used 

cannot be correlated to the aquifer material.

An electromagnetic-induction log is used to 

evaluate lithologic variability and to identify 

electrically conductive fluids by recording the 

electrical conductivity of the material and ground water 

surrounding the borehole. As with natural gamma 

radiation, the electrical conductivity of clayey material 

generally is higher than that of coarse-grained deposits. 

Major factors affecting the response of the 

electromagnetic-induction tool are the dissolved-solids 

concentration of the ground water and of the clay, and 

conversely, the sand content of the aquifer material. 

The electromagnetic-induction tool measures the 

electrical conductivity within a zone from 10 to 50 in. 

from the well. Because direct contact with a conductive 

medium is not required, induction logs are especially 

useful for logging the dry portion of boreholes and are 

unaffected by the presence of polyvinyl chloride well 

casings. Electromagnetic-induction logging does not 

work in metal casings.

Geophysical logs do not show a unique response 

to a particular rock or aquifer type, but rather can be 

used as a qualitative tool to help correlate layers in the 

subsurface. When natural gamma radiation and 

electromagnetic-induction logs are compared for a 

particular well, similar responses are likely the result of 

changes in clay mineral content with depth. An 

increase in electrical conductivity without a 

corresponding increase in natural gamma radiation 
Introduction 9

could result from ground water containing more 

dissolved solids. Geophysical logs should be used in 

conjunction with lithologic logs, water-quality data, 

and other information to provide the most reasonable 

interpretation of the aquifer material in the vicinity of 

the well.

Hydraulic Conductivity and Transmissivity

Slug tests were done at most of the monitoring 

wells to estimate the hydraulic conductivity or 

transmissivity of the shallow aquifer. Hydraulic 

conductivity is the measure of the rate at which water 

can move through a porous material. The transmissivity 

of an aquifer is equal to the hydraulic conductivity 

multiplied by the saturated thickness of the aquifer. The 

rate that water moves through the basin-fill deposits 

can affect water quality.

The hydraulic conductivity of an aquifer open to 

a well can be estimated from the rate in water-level 

decline or recovery after a cylinder with a known 

volume (slug) has been added or removed from the 

water. A pressure transducer measured water-level 

change at several time intervals in response to the water 

displacement. Water-level data were stored in a data 

recorder. The slug was quickly lowered below the 

water surface in the well and the water-level response 

in the well was periodically measured until it regained 

Fine sand from 34 to 35 feet below land surface at well 8.

Core is about 3.5 inches in diameter.

35 feet 34 feet

11 feet 11.5 feet

Sand and gravel from about 11 to 11.5 feet below land surface at well 2.

Core is about 3.5 inches in diameter.

Figure 4. Cores of basin-fill deposits from two monitoring wells in Salt Lake Valley, Utah.
10 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

a state of equilibrium with the aquifer. Water- level 

recovery was monitored by the same process after the 

slug was quickly raised out of the water. 

The Bouwer and Rice method was used to 

estimate hydraulic conductivity from slug tests done at 

eight wells and is discussed by Bouwer and Rice 

(1976) and Bouwer (1989). The Cooper, Bredehoeft, 

and Papadopulos method (Cooper and others, 1967) 

was used to estimate transmissivity from slug tests 

done at 12 wells. These methods assume that the 

aquifer is homogeneous and of uniform thickness, has 

infinite areal extent, has no leakage from above or 

below the developed zone, and that the slug is 

instantaneously added or removed from the well. The 

Bouwer and Rice method assumes that the aquifer is 

unconfined or confined and that flow is steady, while 

the Cooper, Bredehoeft, and Papadopulos method 

assumes that the aquifer is confined and that flow is 

unsteady.

A limitation of slug tests in estimating hydraulic 

conductivity and transmissivity is that the value 

determined is only representative of the aquifer near 

the screened interval and is influenced by the grain size 

of the material in the area around the screen (Bouwer, 

1989). Fine-grained deposits around the screen can 

impede the flow of water into and out of the well if it 

has not been properly completed and developed. The 

thickness of the developed zone typically is unknown. 

The computer program AQTESOLV version 2.13 

(Duffield, 1999) was used to analyze the slug-test data. 

Specific capacity is the yield of a well per unit of 

drawdown and was calculated from the pumping rate 

divided by the drawdown measured while purging the 

monitoring wells prior to sampling. Transmissivity can 

be estimated by using specific capacity, storage 

coefficient, pumping duration, and well diameter if the 

well is assumed to be 100 percent efficient (Theis, 

1963). 

Water-Level and Temperature Fluctuations

Water-level and temperature fluctuations can 

indicate sources of recharge and discharge and how 

connected the aquifer is to activities and processes 

occurring at the land surface. Water-level fluctuations 

were measured in 30 monitoring wells from September 

1999 to July 2001. Depth to water was measured with a 

calibrated tape on a monthly basis. Pressure sensors 

and data loggers were installed in several wells and 

water levels were measured on an hourly basis. Water 

levels measured by pressure sensors were checked 

against water levels measured by tape and the sensors 

were recalibrated if necessary to make the two levels 

match.

Temperature sensors and loggers were installed 

in 23 monitoring wells and recorded water temperature 

on an hourly basis during the study. Generally, the 

sensors were set in the well at about the top of the 

screened interval so that the water temperature was 

believed to be representative of the aquifer. The sensor 

was placed within the screened interval of the well if 

the water level was near the top of the screen.

HYDROGEOLOGY OF SHALLOW BASINFILL DEPOSITS

Lithologic and Borehole Geophysical Logs

Lithologic, natural gamma radiation, and 

electromagnetic-induction data from 30 monitoring 

wells were compared to qualify the connection 

between land surface and the underlying ground water 

(pl. 1). Natural gamma radiation varied from 0 to about 

100 gamma counts per second for basin-fill deposits on 

the west side of the valley and from 0 to about 150 

gamma counts per second for deposits on the east side. 

The basin-fill deposits on the east side of the valley 

contain rocks derived from uranium-rich igneous 

sources that affect the amount of natural gamma 

radiation. Intervals around the well casings with 

bentonite pellets or chips had higher values of natural 

gamma radiation (pl. 1). Electrical conductivity shown 

on the electromagnetic-induction logs ranged from 0 to 

more than 300 micromhos per meter, but most values 

were less than 150 micromhos per meter. The 

geophysical logs shown on plate 1 do not have 

consistent scales so that geophysical logs from each 

well could be compared to its associated lithologic log.

Silt and clay layers noted on lithologic logs 

correlate with increases in electrical conductivity and 

natural gamma radiation shown on many of the 

electromagnetic-induction and natural gamma logs. 

Relatively large increases in electrical conductivity 

determined from the electromagnetic-induction logs 

with no major changes in natural gamma radiation 

were measured at wells 5, 18, 22, 27, and 32 (pl. 1). 

These increases are likely caused by increased 
Hydrogeology of Shallow Basin-Fill Deposits 11

dissolved solids content in the ground water. Intervals 

with high electrical-conductivity measurements at 

wells 5, 11, 18, and 27 correspond to areas in which 

water was present during drilling. Increases in 

electrical conductivity also occur above the water table 

(well 18 at 15 ft, well 22 at 6 ft, and well 32 at 55 ft) 

and may represent pulses of more conductive water 

moving downward through the unsaturated zone to the 

water table. The source of the dissolved solids in 

ground water may be naturally occurring or from 

anthropogenic sources such as salt applied to roads for 

de-icing in the winter or relatively conductive 

compounds such as oil or solvents.

The coarsest and best-sorted sediments 

penetrated by the wells were present on the east side of 

the valley where high-energy streams from the Wasatch 

Range deposited deltas in Lake Bonneville. Sandy and 

silty clay deposited sometime after Lake Bonneville 

receded from the Provo shoreline level was mapped at 

land surface in many areas on the west side of the 

valley (Miller, 1980). Monitoring wells 8, 14, and 31 

are above the extent of these fine-grained deposits. 

Basin-fill deposits logged near land surface in wells 8 

and 31 correlate to mapped sands and gravels deposited 

during the Provo level of the lake. Sandy silt and clay 

logged near land surface in well 14 was deposited in a 

lower energy environment.

Unconfined conditions were present at 7 of 20 

monitoring wells on the west side and at 2 of 10 wells 

on the east side of the valley. The aquifer is considered 

unconfined if the water level in the completed well is at 

or below the level at which it was encountered during 

drilling. Confined conditions are present if the water 

level rose above the level at which it was first 

encountered in the subsurface. Fine-grained deposits 

confine the ground water.

The water level remained at about the same level 

it was at when the well was drilled or declined after the 

well was completed in wells 4, 8, 20, 30, 31, 32, 33, 35, 

and 41 (pl. 1). The shallow aquifer is unconfined in 

these areas; therefore, water at the land surface has the 

potential to move downward to the water table. 

Anthropogenic compounds such as VOCs and 

pesticides were detected in water sampled from most of 

these wells (Thiros, 2003). Water from well 35 was not 

sampled because the water level declined below the 

bottom of the well, and water from well 32 did not 

contain detectable concentrations of VOCs or 

pesticides. The depth to water in well 31, in the 

southwestern part of the valley, is about 145 ft below 

land surface. Many domestic wells in the area draw 

water from near the surface of the water table because 

the water table is so deep.

Water levels measured after well completion rose 

about 5 ft or less from the levels first measured in wells 

5, 6, 7, 14, 22, 25, 27, and 39 (pl. 1). Fine-grained 

deposits could confine the aquifer open to these wells, 

although confining layers are not evident from all of 

the logs (wells 5 and 22). Also, some of the rise may be 

attributable to seasonal changes in the aquifer that 

occurred between when the well was drilled and when 

the water level was measured later in the summer. The 

highest concentrations of tetrachloroethylene (PCE) in 

monitoring wells were detected in water from wells 5 

and 27 (Thiros, 2003), which indicates connection with 

the land surface at these sites.

Water levels rose as much as 32 ft above the 

levels first measured in wells 1, 2, 3, 9, 10, 11, 17, 18, 

24, 26, 29, 34, and 37 (pl. 1). Fine-grained deposits 

noted on the lithologic logs for these wells at or above 

the screened interval confines the ground water. 

Although confined conditions exist, manmade 

chemicals such as atrazine and PCE were detected in 

water sampled from these wells (Thiros, 2003). The 

recharge area for these wells is likely upgradient to the 

east or west where confining layers are absent or 

discontinuous. 

Hydraulic Conductivity and Transmissivity

Data were collected from 20 of the monitoring 

wells to estimate the hydraulic conductivity and 

transmissivity of the shallow ground-water system 

(table 2). The rate that water moves through the 

subsurface can be used with water-quality data to better 

understand the effects of residential and commercial 

land uses on the underlying shallow ground water. 

Hydraulic conductivity was estimated from slug tests 

done on 8 monitoring wells completed in an 

unconfined or confined part of the shallow aquifer, and 

transmissivity was estimated from tests done on 12 

monitoring wells completed in a confined part of the 

shallow aquifer (fig. 5).

Hydraulic-conductivity values of the shallow 

aquifer ranged from 30 ft/d at well 27 to 540 ft/d at 

well 1. Hydraulic-conductivity values were determined 

for the aquifer at the screened interval of the 

monitoring well and represent mostly horizontal flow 

through more permeable deposits. Overlying layers of 
12 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

fine-grained deposits may have a vertical hydraulicconductivity value of from 0.01 to 1 ft/d (Thiros, 1995), 

resulting in slower overall water movement. Hydraulicconductivity values of from 0.03 to as much as 3,000 

ft/d with a log-normalized mean value of 30 ft/d have 

been reported for coarse-grained basin-fill deposits in 

the Basin and Range province (Bedinger and others, 

1987, p. 39). 

Transmissivity values of the shallow aquifer 

ranged from 3 ft2/d at well 4 to 1,070 ft2/d at well 33. If 

the thickness of the shallow aquifer at well 4 is about 

10 ft and at well 33 about 50 ft, then the hydraulicconductivity value would range from about 0.3 to 20 

ft/d. 

There is a close linear relation between 

transmissivity determined from slug-test analysis and 

transmissivity estimated from specific capacity. The 

regression line fit to the data has an R2 (the fraction of 

the variance explained by regression) of 0.94 that 

indicates that transmissivity estimates derived from the 

slug tests are similar to those derived from specificcapacity values. The transmissivity values for well 33 

derived from slug-test and specific-capacity data were 

not used to calculate the regression line fit because they 

are about an order of magnitude greater than those for 

the other wells.

Water-Level and Temperature Fluctuations

The depth to water in the wells was monitored to 

determine how the shallow aquifer responds to changes 

in recharge and discharge. The water-level surface 

determined from water levels measured in the 30 wells 

in March 2000 is shown in figure 6. The water-level 

surface generally correlates with the land surface, 

sloping toward the center of the valley or to the northnortheast in the northwestern part of the valley. Depth 

to ground water measured in the monitoring wells on 

the southeastern side of the valley probably represents 

both perched ground water and the shallow aquifer 

because of discontinuous layers of clay in the area. The 

relation between the different perched ground-water 

areas and the shallow aquifer is not known; therefore, 

the water-level surface for shallow ground water on the 

southeastern side of the valley may not be continuous. 

Water-level fluctuations were measured in the 30 

monitoring wells from 1999 to July 2001 (pl. 1). 

Changes in water levels measured in these wells tend to 

follow a seasonal pattern that is dependent upon water 

use and location, similar to that noted for other 

monitoring wells completed at the bottom of the 

shallow aquifer in Salt Lake Valley (Thiros, 1995, p. 

38). Generally, water-level changes measured in wells 

on the west side of the valley followed a seasonal trend 

while wells on the east side showed less fluctuation or a 

gradual decline during the 2-year period. This may 

indicate that a higher percentage of recharge to the 

shallow ground-water system on the west side is from 

somewhat consistent seasonal sources, such as canals 

and unconsumed irrigation water, as compared to 

recharge on the east side.

Water levels for monitoring wells near canals or 

ditches that carry water for irrigation typically are 

highest in the late summer or fall in response to 

infiltration of unconsumed irrigation water. Water 

levels in these wells are lowest in the spring before 

irrigation begins. Water levels rose about 10 ft from 

June to October in well 31, about 4,000 ft east 

(downgradient) from the Provo Reservoir Canal and 

about 400 ft west (upgradient) of the Utah Lake 

Distributing Canal. Losses from these two canals to the 

ground-water system in the vicinity of well 31 were 

determined to be about 1.8 ft3/s/mi (Herbert and others, 

1985). Water levels rose about 6 ft from May to 

October in well 33, next to the Utah and Salt Lake 

Canal in West Jordan. Losses from the adjacent canal 

and the two upgradient canals near well 33 totaled 

about 2.5 ft3/s/mi (Herbert and others, 1985).

Monitoring wells 26S (31.5 ft deep) and 26D 

(77.5 ft deep) are nested together in well 26 next to 

Little Cottonwood Creek on the east side of the valley. 

Water levels in the wells rise in the spring and decline 

the rest of the year (pl. 1). Snowmelt runoff in the 

stream measured at gaging station 10167800, about 0.5 

mi west of well 26D, was followed by an increase in 

water level in well 26D within 1 to 2 days in both the 

spring of 2000 and 2001 (fig. 7).
Hydrogeology of Shallow Basin-Fill Deposits 13

The water-level change measured in monitoring 

well 10 was different from that measured in other wells 

in the area. Water levels peaked during March-April 

and were lowest during August-September. The depth 

to water in this well is below that of nearby loweraltitude wells 6 and 9. Well 10 may be open to a deeper, 

more isolated part of the shallow ground-water system, 

although it was completed in the first saturated zone in 

the subsurface and anthropogenic compounds were 

detected in the water. 

The water level in well 4 was higher than that in 

upgradient well 3 and in nearby wells 2 and 6. Low 

aquifer transmissivity may cause local recharge in the 

area to form a ground-water mound relative to other 

areas. The southern extent of the Granger Fault is 

mapped near well 4 (Personius and Scott, 1992) and 

also may influence ground-water flow in the area.

Water levels measured in monitoring wells 

completed in the shallow ground-water system near 

large-capacity public-supply wells varied in response 

to ground-water withdrawals from the deeper confined 

aquifer. Water levels measured in the three monitoring 

wells installed near public-supply wells during this 

study (wells 8, 32, and 18) did not follow a seasonal 

pattern during the 2 years like other wells influenced by 

streams and canals. The water level in well 18 dropped 

more than 5 ft between March and October 2000, the 

period when ground water is pumped from the deeper 

aquifer to meet peak demands for public supply in the 

area. The water level in well 32 declined about 3 ft 

from December 1999 to July 2001. This well is 

adjacent to a golf course and likely received a steady 

amount of recharge from unconsumed irrigation water. 

Table 2. Specific-capacity and slug-test data for 20 monitoring wells in Salt Lake Valley, Utah

[Specific capacity is well discharge, in gallons per minute, divided by water-level decline, in feet. Estimated aquifer thickness and storage coefficient are 

used with specific-capacity value to estimate transmissivity. —, no data]

Well number

(fig. 3, 

table 1)

Specific 

capacity

Estimated 

aquifer

thickness

(feet)

Estimated 

storage coefficient

Transmissivity 

estimated from 

specific-capacity 

data

(feet squared per 

day)

Transmissivity 

estimated from slugtest data

(feet squared per 

day)

Estimated

hydraulic 

conductivity 

(feet per day)

1 — 10 0.001 530 — 540

2 1.72 10 .001 420 — 90

3 .24 10 .001 50 90 —

4 .2 10 .001 5 3 —

5 1.61 20 .1 230 — 200

6 .44 25 .1 50 — 60

7 .93 20 .001 210 250 —

9 .14 20 .001 30 50 —

14 .5 20 .01 10 9 —

17 .48 20 .0005 120 90 —

18 .69 20 .0005 180 200 —

25 2.08 40 .1 300 — 390

26D .30 48 .0005 70 60 —

27 .42 30 .1 50 — 30

29 .5 20 .005 10 20 —

30 2.80 20 .1 330 — 390

33 2.26 20 .0005 1,610 1 1,070 —

34 1.49 20 .1 190 — 150

37 .4 10 .005 10 7 —

41 .47 17 .0005 120 100 —

1Value not included in the calculation of the regression equation for the relation between slug-test and specific-capacity derived transmissivity. 
14 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

Base from U.S. Geological Survey digital line graph data, 1:100,000, 1979 and 1980

Universal Transverse Mercator projection, Zone 12

Great

Salt

Lake

Tailings ponds

40r30'

40r45'

Jordan River

0 3 6 KILOMETERS

0 3 6 MILES

West

Valley

City

Salt

Lake

City

South

Jordan

West

Jordan

Murray

Sandy

Draper

Riverton

EXPLANATION

Area of recent residential and commercial land use

Perched aquifer—Data from Hely and others, 1971

Discharge area

Primary recharge area

Secondary recharge area

Approximate boundary of basin-fill deposits in Salt Lake Valley

Monitoring well—Number in blue is the hydraulic conductivity, in feet per day; Number

in black is the transmissivity, in feet squared per day

90

90 3

200 60

250 50

9

90

390

1,070

200

30 20 60

150

7

100

100

112r07'30" 111r48'

SALT LAKE COUNTY

DAVIS COUNTY

SALT LAKE COUNTY

UTAH COUNTY

540

390

Figure 5. Distribution of hydraulic-conductivity and transmissivity values determined from slug tests done at selected monitoring wells in Salt 

Lake Valley, Utah.
Hydrogeology of Shallow Basin-Fill Deposits 15

4,300

4,450

4,500

4,550

4,350

4,400

4,350

4,400

4,450

4,450

4,500

4,650

4,600

4,550

4,250

Base from U.S. Geological Survey digital line graph data, 1:100,000, 1979 and 1980

Universal Transverse Mercator projection, Zone 12

Great

Salt

Lake

Tailings ponds

40r30'

40r45'

Jordan River

0 3 6 KILOMETERS

0 3 6 MILES

West

Valley

City

Salt

Lake

City

South

Jordan

West

Jordan

Murray

Sandy

Draper

Riverton

EXPLANATION

Area of recent residential and commercial land use

Perched aquifer—Data from Hely and others, 1971

Discharge area

Primary recharge area

Secondary recharge area

Line of equal water-level altitude—Shows altitude of water level in shallow aquifer and perched zones, March 2000.

Contour interval is 50 feet. Dashed where approximate

Approximate boundary of basin-fill deposits in Salt Lake Valley

Monitoring well

112r07'30" 111r48'

SALT LAKE COUNTY

DAVIS COUNTY

SALT LAKE COUNTY

UTAH COUNTY

Figure 6. Water-level surface for the shallow ground-water system, Salt Lake Valley, Utah, March 2000.
16 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

Although there is not a direct correlation between 

water-level response in well 32 and pumping in the 

nearby public-supply well, withdrawals from the 

deeper aquifer may affect water levels in the shallow 

system in this area.

Water temperature was monitored in 23 wells to 

determine if the effects of surface-water recharge to the 

shallow aquifer could be measured. Only water 

temperature changes measured in wells 26S and 26D 

(fig. 7) showed a correlation with changes in groundwater levels and variations in streamflow measured in 

nearby Little Cottonwood Creek. The period of 

snowmelt runoff in the stream corresponded with an 

increase (rise) in water level and a decrease in water 

temperature in well 26D in both the spring of 2000 and 

2001. The ground-water temperature rose within days 

after streamflow decreased to less than 5 ft3/s in the 

middle of June.

Water-temperature changes recorded at other 

times of the year also correlated with water-level 

changes in well 26D. Water temperature in the well 

increased from about 9.0oC in June to 15.0oC in 

September while the water level declined about 2 ft. 

This ground water likely is recharged during the 

summer from unconsumed irrigation water and canal 

losses. Water levels declined about 8 ft from midOctober, when irrigation stopped, until April, when 

snowmelt runoff started. The water temperature in the 

well decreased from 14.0 to 12.5oC during this period 

of little recharge to the ground-water system.

300

200 25

20

100 30

0 35

Transducer-measured water level

Water temperature

Tape-measured water level

Little Cottonwood Creek discharge at gaging

station 10167800

WATER LEVEL, IN FEET BELOW LAND SURFACE

MEAN DAILY DISCHARGE, IN CUBIC FEET PER SECOND

WATER TEMPERATURE, IN DEGREES CELSIUS

Mar April June Aug Sept Nov Jan Feb May July

5

10

15

20

May July Oct Dec April Mar June

2000 2001

Figure 7. Water level and water temperature measured in monitoring well 26D and discharge determined for Little Cottonwood Creek at 

gaging station 10167800, Salt Lake Valley, Utah, 2000-2001.
Hydrogeology of Shallow Basin-Fill Deposits 17

Little or no change in water temperature (less 

than 0.2oC change) was measured in monitoring wells 

that had a depth to water of more than about 40 ft (fig. 

8), except for well 26D. Water temperature fluctuated 

seasonally in the wells with a water level less than 

about 40 ft, except for well 26S. The shallower the 

water level in the well, the greater the watertemperature change measured during the study.

The coldest monthly mean air temperature in 

Salt Lake Valley is about -2oC in January (Ashcroft and 

others, 1992). The lowest mean water temperatures 

measured in wells with water levels less than about 40 

ft below land surface occurred about 3 to 9 months later 

(fig. 9). Seasonal variations in air temperature can 

conduct as much as 10 meters (33 ft) or so below the 

land surface (Freeze and Cherry, 1979, p. 508) before 

being damped out and are the cause for most of the 

water-temperature variations measured in the 

monitoring wells. This lag in wate-temperature change 

with water depth is related to how long heat takes to 

conduct through the subsurface. Generally, the deeper 

the water level, the greater the lag time between the 

coldest air and water temperatures, and the smaller the 

annual water-temperature change (fig. 9). No lag in 

temperature was noted for wells with water levels 

deeper than about 31 ft below land surface (well 1).

0

25

50

75

100

125

150

0123456

WATER LEVEL, IN FEET BELOW LAND SURFACE

2 3 4 5 6 7 8 9 10

LAG IN WATER-TEMPERATURE CHANGE, IN MONTHS

0

5

10

15

20

25

30

WATER LEVEL, IN FEET BELOW LAND SURFACE

35

R2 = 0.8506

WATER-TEMPERATURE CHANGE, IN DEGREES CELSIUS

Figure 8. Relation between water level and water temperature in selected monitoring wells in Salt Lake Valley, Utah.
18 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

Well 22

Well 29

Well 2

Tape-measured water level

Transducer-measured water level

Water temperature measured in well

WATER LEVEL, IN FEET BELOW LAND SURFACEWATER TEMPERATURE, IN DEGREES CELSIUS

22.0

21.0

20.0

SDM J

12.0

12.5

13.0

13.5

21.5

20.5

1999

J F J

2000 2001

ON M A AS D M JJ ON M J F A 10.0

9.5

9.0

8.5

8.0

8

10

12

14

16

22

21

20

19

18

13

14

15

16

17

Figure 9. Water-level and water-temperature fluctuations measured in monitoring wells 2, 22, and 29, Salt Lake Valley, Utah.
Hydrogeology of Shallow Basin-Fill Deposits 19

The temperature of recharge water infiltrating 

from the land surface may cause some of the watertemperature change measured at the monitoring wells 

in addition to any change caused by air-temperature 

changes. The water level in well 22 began to rise in 

May and increases in water temperature followed about 

2 months later (fig. 9). The water-level rise is attributed 

to recharge from unconsumed irrigation water that is 

applied during the warmer growing season. The water 

temperature in well 2 increased to 16.5oC in February 

and March, about when water levels were the lowest in 

the well (fig. 9). Because increases in water 

temperature and level do not relate more closely, it is 

unlikely that infiltrating recharge water affects water 

temperature in well 2.

Water temperature in well 29 fluctuated from a 

high of 15.6oC in October 2000 to a low of 10.0oC in 

late March 2001 (fig. 9). The water level in the well is 

about 9 ft below land surface and the temperature 

sensor was set at about 20 ft below land surface at the 

top of the screened interval. The period of recharge for 

water from this well was likely during the 1960s on the 

basis of a high tritium concentration (Thiros, 2003); 

therefore, recharge likely is not responsible for the 

change in water temperature. Shallow water applied for 

lawn irrigation is perched on top of the 14-ft-thick layer 

of clay and interbedded sand that confines the water in 

well 29 and can be seen draining near the well. Heat 

from this water applied during the summer probably 

conducts through the clay to the underlying aquifer 

with no actual movement of water.

Water-Level Gradients

The monitoring wells were installed in areas 

assumed to have a downward hydraulic gradient from 

the shallow to the deeper aquifers in the valley, the 

secondary recharge area (fig. 3), on the basis of 

information from well drillers' logs (Anderson and 

others, 1994). Comparison of water levels measured in 

the monitoring wells and deeper wells in the same area 

indicate a downward gradient on the east side of the 

valley (fig. 10) where water levels in some deeper wells 

are as much as 300 ft below those measured in nearby 

shallow monitoring wells.

A large area in the southeastern part of the valley 

contains perched ground water (fig. 10) where the 

bottom of a confining layer lies above the water table 

(Hely and others, 1971, p. 110). There is evidence that 

an unsaturated zone is present between the shallow 

ground water and the deeper aquifer near wells 29 and 

32 on the basis of observations noted on drillers' logs 

for wells in the area. The water level in the deeper 

aquifer is about 300 ft below land surface compared to 

near land surface in well 29 and about 70 ft below land 

surface in well 32. Although the potential exists for 

shallow water to move downward because of the 

vertical hydraulic gradient, available water-quality 

information for the deeper aquifer indicates little or no 

mixing (Thiros, 2003). Confining layers and dispersion 

through the highly transmissive deeper aquifer limit 

connection between the aquifers in the area.

Water levels in the shallow and deeper aquifers 

in the secondary recharge area on the west side of the 

valley were similar. Seepage from canals and 

unconsumed irrigation are major sources of recharge to 

the basin-fill aquifers in this area. Canal losses on the 

west side are estimated to be about 15,000 acre-ft/yr as 

determined from measured losses to the ground-water 

system (Herbert and others, 1985). These losses are 

assumed to occur over a 6-month period when water is 

distributed in the canals. Although the canals mainly 

flow through the secondary recharge area, seepage 

losses can recharge both the shallow and deeper 

aquifers.

Water levels measured in the monitoring wells 

and nearby wells completed in the deeper aquifer 

indicate that the vertical gradient can change with time 

and stresses on the system. Water levels have been 

measured at a monitoring well completed in the deeper 

aquifer near monitoring well 11 from 1966 to present 

(fig. 11). The deeper well has three separate perforated 

intervals from 187 to 372 ft, and the shallow well is 

screened from 73 to 83 ft below land surface. Water 

levels measured in the two wells during this study 

indicate an upward gradient of about 10 ft. Water 

levels in the deeper well in the 1980s were about 15 ft 

below what was measured in the shallower well during 

1999-2001 because of pumping from the principal 

aquifer in the area. This indicates that a downward 

gradient can exist if the shallow aquifer does not 

respond in the same way as the deeper one to changes 

in recharge and discharge. Withdrawals from the 

deeper aquifer in the area would likely cause the water 

level to decline below that in the shallow aquifer, 

resulting in a downward gradient between the aquifers. 

A downward vertical hydraulic gradient was 

measured at the three monitoring wells nested with 

public-supply wells. Water levels measured in the 
20 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

Base from U.S. Geological Survey digital line graph data, 1:100,000, 1979 and 1980

Universal Transverse Mercator projection, Zone 12

Great

Salt

Lake

Tailings ponds

40r30'

40r45'

Jordan River

0 3 6 KILOMETERS

0 3 6 MILES

West

Valley

City

Salt

Lake

City

South

Jordan

West

Jordan

Murray

Sandy

Draper

Riverton

EXPLANATION

Area of recent residential and commercial land use

Perched aquifer—Data from Hely and others, 1971

Discharge area

Primary recharge area

Secondary recharge area

Approximate boundary of basin-fill deposits in Salt

Lake Valley

112r07'30" 111r48'

SALT LAKE COUNTY

DAVIS COUNTY

SALT LAKE COUNTY

UTAH COUNTY

Water level in shallow and deeper aquifer is

about the same

Water level in shallow aquifer is above or below

water level in deeper aquifer—Number is

difference in feet. Arrow shows direction of

potential ground-water movement (gradient)

from shallow aquifer to deeper aquifer

100

50

5

80

100

100

200

300

100

300

100

Figure 10. Direction of vertical water-level gradient and the difference between water levels in the shallow ground-water system and the 

deeper aquifer in Salt Lake Valley, Utah.
Hydrogeology of Shallow Basin-Fill Deposits 21

shallow wells declined when public-supply wells in the 

area were pumping, indicating a possible connection 

between the two aquifers. The potential exists for 

shallow water to move downward if the intervening 

confining layers are discontinuous, thin, have a high 

enough permeability, or if the deeper well serves as a 

conduit for ground-water movement as a result of its 

completion.

The static water level in well 8 on the west side 

of the valley is about the same as that measured in a 

nearby public-supply well. The water level in the 

public-supply well drops almost 100 ft when pumping. 

A thick layer of clay noted on the drillers’ log (124 to 

182 ft below land surface) is present between the water 

table and the top of the screened interval in the deeper 

well. Specific conductance measured in water from the 

shallow and deeper wells under both static and 

pumping conditions was compared. The specific 

conductance of water was about 1,000 μS/cm in the 

shallow well under both static and pumping conditions 

and in water from the deeper well while pumping. The 

specific conductance of water in the deeper well at 

about 90 ft below land surface under static conditions 

was 350 μS/cm. The specific conductance of water 

measured in the deeper well when it was not pumping 

is probably representative of the water in the aquifer at 

the screened interval (172 to 253 ft below land surface). 

The higher specific conductance measured in water 

pumped from the deeper well may be caused by 

shallow water that has moved downward despite the 

presence of the intervening clay layer. Volatile organic 

compounds and elevated nitrate concentrations 

measured in water from the shallow well also were 

detected in water from the deeper well, indicating a 

likely connection between the two aquifers in this area 

(Thiros, 2003). 

Well 32, on the east side of the valley, is also 

near a public-supply well. The water level in the 

shallow well is separated from the first screened 

interval in the deeper well by about 440 ft of 

interbedded sand and clay with some gravel. The water 

level measured in the shallow well is about 210 ft 

Monitoring

well 11

WATER LEVEL, IN FEET BELOW LAND SURFACE

90

85

80

75

70

65

60

55

50

45

40

Deeper aquifer

monitoring well

1965 1975 1985 1995 2004

Figure 11. Water levels measured in two monitoring wells near Kearns, Utah.
22 Hydrogeology of Shallow Basin-Fill Deposits in Areas of Salt Lake Valley, Salt Lake County, Utah

above that in the deeper well under non-pumping 

conditions, indicating a large downward hydraulic 

gradient between the aquifers. Water levels in the 

shallow well have declined (pl. 1), probably in 

response to withdrawals from the deeper aquifer. 

Although no thick layers of clay are noted on the 

lithologic log of the deeper well, the layers of clay 

likely impede vertical movement of water. No 

anthropogenic compounds were detected in water from 

either well (Thiros, 2003).

SUMMARY

A study of recently developed 

residential/commercial areas of Salt Lake Valley, Utah, 

was done during 1999-2001 in areas in which shallow 

ground water has the potential to move to a deeper 

aquifer that is used for public supply. Thirty monitoring 

wells were drilled and sampled in 1999 as part of the 

study. The ground water at the monitoring-well sites 

was under either unconfined or confined conditions, 

depending on depth to water and the presence or 

absence of fine-grained deposits. The wells were 

completed in the shallowest water-bearing zone 

capable of supplying water. Monitoring-well depths 

range from 23 to 154 ft. Lithologic, geophysical, 

hydraulic-conductivity, transmissivity, water-level, and 

water-temperature data were obtained for or collected 

from the wells.

Silt and clay layers noted on lithologic logs 

correlate with increases in electrical conductivity and 

natural gamma radiation shown on many of the 

electromagnetic-induction and natural gamma logs. 

Relatively large increases in electrical conductivity 

determined from the electromagnetic-induction logs, 

with no major changes in natural gamma radiation are 

likely caused by increased dissolved-solids content in 

the ground water. Some intervals with high electrical 

conductivity correspond to areas where water was 

present during drilling.

Data were collected from 20 of the monitoring 

wells to estimate the hydraulic conductivity and 

transmissivity of the shallow ground-water system. 

Hydraulic-conductivity values of the shallow aquifer 

ranged from 30 to 540 ft/d. Transmissivity values of the 

shallow aquifer ranged from 3 to 1,070 ft2/d. There is a 

close linear relation between transmissivity determined 

from slug-test analysis and transmissivity estimated 

from specific-capacity data.

Water-level fluctuations were measured in the 30 

monitoring wells from 1999 to July 2001. Generally, 

water-level changes measured in wells on the west side 

of the valley followed a seasonal trend and wells on the 

east side showed less fluctuation or a gradual decline 

during the 2-year period. Water levels measured in 

monitoring wells completed in the shallow groundwater system near large-capacity public-supply wells 

varied in response to ground-water withdrawals from 

the deeper confined aquifer. The shallower the water 

level in the well, the greater the water-temperature 

change measured during the study.

Comparison of water levels measured in the 

monitoring wells and deeper wells in the same area 

indicate a downward gradient on the east side of the 

valley. Water levels in the shallow and deeper aquifers 

in the secondary recharge area on the west side of the 

valley were similar. Water levels measured in the 

monitoring wells and nearby wells completed in the 

deeper aquifer indicate that the vertical gradient can 

change with time and stresses on the system.

REFERENCES CITED

Anderson, P.B., Susong, D.D., Wold, S.R., Heilweil, V.M., 

and Baskin, R.L., 1994, Hydrogeology of recharge 

areas and water quality of the principal aquifers along 

the Wasatch Front and adjacent areas, Utah: U.S. 

Geological Survey Water-Resources Investigations 

Report 93-4221, 74 p.

Ashcroft, G.L., Jensen, D.T., and Brown, J.L., 1992, Utah 

climate: Utah Climate Center, Utah State University, 

Logan, Utah, 125 p.

Bedinger, M.S., Langer, W.H., and Reed, J.E., 1987, 

Synthesis of hydraulic properties of rocks with 

reference to the Basin and Range province, 

southwestern United States, in Selected papers in the 

hydrologic sciences 1986: U.S. Geological Survey 

Water-Supply Paper 2310, p. 35-43.

Bouwer, Herman, 1989, The Bouwer and Rice slug test - an 

update: Ground Water, v. 27, no. 3, p. 304-309.

Bouwer, Herman, and Rice, R.C., 1976, A slug test method 

for determining hydraulic conductivity of unconfined 

aquifers with completely or partially penetrating wells: 

Water Resources Research, v. 12, no. 3, p. 423-428.
References Cited 23

Cooper, H.H., Jr., Bredehoeft, J.D., and Papadopulos, I.S., 

1967, Response of a finite-diameter well to an 

instantaneous charge of water: Water Resources 

Research, v. 3, no. 1, p. 263-269.

Duffield, G.M., 1999, AQTESOLV for Windows, version 

2.13: HydroSOLVE, Inc., Reston, Va.

Fenneman, N.M., 1931, Physiography of the Western United 

States: New York, McGraw-Hill, 534 p.

Freeze, R.A., and Cherry, J.A., 1979, Groundwater: New 

Jersey, Prentice-Hall, Inc., 604 p.

Hely, A.G., Mower, R.W., and Harr, C.A., 1971, Water 

resources of Salt Lake County, Utah: Utah Department 

of Natural Resources Technical Publication No. 21, 

244 p.

Herbert, L.R., Cruff, R.W., and Waddell, K.M., 1985, 

Seepage study of six canals in Salt Lake County, Utah, 

1982-83: Utah Department of Natural Resources 

Technical Publication No. 82, 95 p.

Keys, W.S., 1990, Borehole geophysics applied to groundwater investigations: U.S. Geological Survey 

Techniques of Water-Resources Investigations, Book 2, 

chap. E2, 150 p.

Lambert, P.M., 1995, Numerical simulation of ground-water 

flow in basin-fill material in Salt Lake Valley, Utah: 

Utah Department of Natural Resources Technical 

Publication No. 110-B, 36 p. 

Lapham, W.W., Wilde, F.D., and Koterba, M.T., 1995, 

Ground-water data-collection protocols and procedures 

for the National Water-Quality Assessment Program: 

selection, installation, and documentation of wells, and 

collection of related data: U.S. Geological Survey 

Open-File Report 95-398, 69 p.

Miller, R.D., 1980, Surficial geologic map along part of the 

Wasatch Front, Salt Lake Valley, Utah: U.S. Geological 

Survey Miscellaneous Field Studies Map MF-1198, 

scale 1:100,000.

Personius, S.F., and Scott, W.E., 1992, Surficial geologic 

map of the Salt Lake City segment and parts of adjacent 

segments of the Wasatch Fault Zone, Davis, Salt Lake, 

and Utah Counties, Utah: U.S. Geological Survey 

Miscellaneous Investigations Series Map I-2106, scale 

1:50,000.

Scott, J.C., 1990, Computerized stratified random siteselection approaches for design of a ground-waterquality network: U.S. Geological Survey WaterResources Investigations Report 90-4101, 109 p.

Theis, C.V., 1963, Estimating the transmissibility of a watertable aquifer from the specific capacity of a well, in

Bentall, Ray, compiler, Methods of determining 

permeability, transmissibility, and drawdown: U.S. 

Geological Survey Water-Supply Paper 1536-I, p. 332-

336.

Thiros, S.A., 1995, Chemical composition of ground water, 

hydrologic properties of basin-fill material, and groundwater movement in Salt Lake Valley, Utah: Utah 

Department of Natural Resources Technical Publication 

No. 110-A, 59 p.

———2003, Quality of shallow ground water in areas of 

recent residential development in Salt Lake Valley, 

Utah: U.S. Geological Survey Water-Resources 

Investigations Report 03-4028, 74 p.