Water Quality in the 

Great Salt Lake Basins

Utah, Idaho, and Wyoming, 1998–2001

U.S. Department of the Interior

U.S. Geological Survey

Circular 1236
Points of Contact and Additional Information

The companion Web site for NAWQA summary reports:

http://water.usgs.gov/nawqa/nawqa_sumr.html/

Other NAWQA summary reports

River Basin Assessments

Acadian-Pontchartrain Drainages (Circular 1232)

Albemarle-Pamlico Drainage Basin (Circular 1157)

Allegheny and Monongahela River Basins (Circular 1202)

Apalachicola-Chattahoochee-Flint River Basin (Circular 1164)

Central Arizona Basins (Circular 1213)

Central Columbia Plateau (Circular 1144)

Central Nebraska Basins (Circular 1163)

Connecticut, Housatonic and Thames River Basins (Circular 

1155)

Cook Inlet Basin (Circular 1240)

Delaware River Basin (Circular 1227)

Delmarva Peninsula (Circular 1228)

Eastern Iowa Basins (Circular 1210)

Georgia-Florida Coastal Plain (Circular 1151)

Great and Little Miami River Basins (Circular 1229) 

Hudson River Basin (Circular 1165)

Island of Oahu (Circular 1239)

Kanawha - New River Basins (Circular 1204)

Lake Erie - Lake Saint Clair Drainages (Circular 1203)

Long Island - New Jersey Coastal Drainages (Circular 1201)

Lower Illinois River Basin (Circular 1209)

Lower Susquehanna River Basin (Circular 1168)

Lower Tennessee River Basin (Circular 1233)

Las Vegas Valley Area and the Carson and Truckee River Basins 

(Circular 1170)

Mississippi Embayment (Circular 1208)

Mobile River Basin (Circular 1231)

New England Coastal Basins (Circular 1226)

Northern Rockies Intermontane Basins (Circular 1235)

Ozark Plateaus (Circular 1158)

Potomac River Basin (Circular 1166)

Puget Sound Basin (Circular 1216)

Red River of the North Basin (Circular 1169)

Rio Grande Valley (Circular 1162)

Sacramento River Basin (Circular 1215)

San Joaquin-Tulare Basins (Circular 1159)

Santa Ana Basin (Circular 1238)

Santee River Basin and Coastal Drainages (Circular 1206)

South-Central Texas (Circular 1212)

South Platte River Basin (Circular 1167)

Southern Florida (Circular 1207)

Trinity River Basin (Circular 1171)

Upper Colorado River Basin (Circular 1214)

Upper Illinois River Basin (Circular 1230)

Upper Mississippi River Basin (Circular 1211)

Upper Snake River Basin (Circular 1160)

Upper Tennessee River Basin (Circular 1205)

Western Lake Michigan Drainages (Circular 1156)

White River Basin (Circular 1150)

Willamette Basin (Circular 1161)

Yakima River Basin (Circular 1237)

Yellowstone River Basin (Circular 1234)

National Assessments

The Quality of Our Nation‘s Waters—Nutrients and Pesticides 

(Circular 1225)

Great Salt Lake Basins contact and Web site:

USGS State Representative

U.S. Geological Survey

Water Resources Discipline

2329 Orton Circle

Salt Lake City, Utah 84119

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

National NAWQA Program:

Chief, NAWQA Program

U.S. Geological Survey

Water Resources Discipline

12201 Sunrise Valley Drive, M.S. 413

Reston, VA 20192

http://water.usgs.gov/nawqa/

Front cover: East shore of Farmington Bay, Great Salt Lake (photograph by Steven Gerner). 

Back cover: Left, sampling Little Cottonwood Creek (photograph by Robert Baskin); center, electrofishing in the Weber River near 

Coalville (photograph by Kidd Waddell); right, Salt Lake City and Wasatch Mountains (photograph courtesy of the Utah Travel Council/

Frank Jensen).
U.S. Department of the Interior

U.S. Geological Survey

Water Quality in the Great Salt Lake Basins, Utah, Idaho, 

and Wyoming, 1998–2001

By Kidd M. Waddell, Steven J. Gerner, Susan A. Thiros, Elise M. Giddings, 

Robert L. Baskin, Jay R. Cederberg, and Christine M. Albano

Circular 1236
Although this report is in the public domain, permission must be secured from the individual copyright owners to 

reproduce any copyrighted materials contained within this report.

Suggested citation:

Waddell, K.M., Gerner, S.J., Thiros, S.A., Giddings, E.M., Baskin, R.L., Cederberg, J.R., and Albano, C.M., 2003, Water 

quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998-2001, U.S. Geological Survey Circular 1236.

Library of Congress Cataloging-in-Publication Data

Water quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998-2001 / by Kidd M. Waddell ... [et al.].

 p. cm. -- (Circular ; 1236)

 Includes bibliographical references.

 ISBN 0-607-96404-9 (alk. paper)

 1. Water quality--Utah--Great Salt Lake Watershed. I. Waddell, K. M. (Kidd M.), 1937- II. Geological Survey (U.S.) III. 

U.S. Geological Survey circular ; 1236. 

 TD224.U8W36 2004

 363.739’42’09792--dc22

 2004041398

U.S. Geological Survey, Reston, Virginia: 2004

U.S. Department of the Interior

GALE A. NORTON, Secretary

U.S. Geological Survey

Charles G. Groat, Director

Free on application to

U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov/

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.
iii

Contents

National Water-Quality Assessment Program ........................................................................iv

What kind of water-quality information does the NAWQA Program provide? ........................... v

Introduction to this Report .............................................................................................vi

Summary of Major Findings ............................................................................................. 1

Stream and River Highlights .................................................................................... 1

Ground-Water Highlights ....................................................................................... 2

Introduction to the Great Salt Lake Basins ........................................................................... 3

Major Findings ............................................................................................................ 6

Water development affects quantity and quality of water resources .................................... 6

Streamflow regulation, such as that in the Bear River Basin, alters daily and seasonal flows 6

Reductions in water quantity also affect water quality in streams ................................. 6

Fish communities in urban streams respond to changes in water quantity ........................ 7

Pumping likely affects the distribution of dissolved solids in the basin-fill aquifer in Salt 

Lake Valley ....................................................................................... 8

Land use influences water quality and aquatic community health .......................................... 8

Undeveloped basins show minimal degradation of water quality and biological communities ... 8

Phosphorus and nitrogen levels are elevated in streams draining agricultural and 

urban areas .................................................................................... 10

Nitrate levels generally are low in the basin-fill aquifers ....................................... 10

Urban storm runoff affects stream chemistry and temperature ................................. 11

Elevated levels of pesticides are most common in urban streams .............................. 12

VOCs are common in urban streams .................................................................. 13

Pesticides and VOCs are detected in basin-fill aquifers underlying all types of land use ...... 15

VOCs and pesticides commonly are detected in shallow ground water and in the 

basin-fill aquifer used for public supply in Salt Lake Valley .............................. 15

Surface-water contaminants and aquatic communities change as watersheds become urbanized 17

PAH levels are elevated in streambed sediment in urban basins and in Farmington Bay ...... 17

Lead concentrations have decreased in Farmington Bay sediments since the 1980s ......... 17

DDT, PCBs, and other organochlorine compounds occur more commonly in fish than 

in sediment in area streams .................................................................. 18

Increased urban land use has altered invertebrate and algal communities ..................... 19

Elevated concentrations of trace elements in sediment and water are related to natural 

sources and past mining activities ............................................................... 21

Minerals in rocks are sources of arsenic and radon in ground water ........................... 21

Past mining activities contribute to elevated levels of trace elements in sediment and 

water .......................................................................................... 22

Increases in levels of trace elements in sediment since the mid-19th century are related to 

smelter emissions ........................................................................... 23

Study Unit Design ................................................................................................... 25

Glossary ............................................................................................................... 27

References Cited ...................................................................................................... 29

Appendix—Water Quality Data from the Great Salt Lake Basins in a National Context ..................... 31
iv

National Water-Quality Assessment Program

The quality of the Nation’s water resources is of great interest 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. Recognizing the need 

for long-term, nationwide assessments of water resources, the U.S. Congress has appropriated funds since 1991 for the USGS to conduct the National Water-Quality Assessment 

(NAWQA) Program. Scientists in the NAWQA Program work with partners in government, 

research, and public interest groups to assess the spatial extent of water-quality conditions, 

how water quality changes with time, and how human activities and natural factors affect water 

quality. This information is useful for guiding water-management and protection strategies, 

research, and monitoring in different hydrologic and land-use settings across the Nation.

The Great Salt Lake Basins is one of 51 water-quality assessments initiated since 1991. 

Together, the 51 major river basins and aquifer systems, referred to as “Study Units,” include 

water resources used by more than 60 percent of the population in watersheds that cover about 

half of the land areas of the conterminous United States. Timing of the assessments varies 

because of the program’s rotational design in which one-third of all Study Units are intensively 

investigated for 3 to 4 years, with trends assessed every 10 years. As indicated on the map, the 

Great Salt Lake Basins is part of the third set of intensive investigations, which began in 1997.

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v

What kind of water-quality information does the NAWQA 

Program provide?

Water-quality assessments by a single program cannot address all of the Nation’s waterresources needs and issues. Therefore, it is necessary to define the context within which 

NAWQA information is most useful. 

• Total resource assessment—NAWQA assessments are long-term and interdisciplinary, 

and include information on water chemistry, hydrology, land use, stream habitat, and 

aquatic life. Assessments are not limited to a specific geographic area or water-resource 

problem at a specific time. Therefore, the findings describe the general health of the total 

water resource, as well as emerging water issues, thereby helping managers and decision 

makers to set priorities.

• Source-water characterization—Assessments focus on the quality of the available, 

untreated resource and thereby complement (rather than duplicate) Federal, State, and 

local programs that monitor drinking water. Findings are compared to drinking-water 

standards and health advisories as a way to characterize the resource.

• Compounds studied—Assessments focus on chemical compounds that have well-established methods of investigation. It is not financially or technically feasible to assess all 

the contaminants in our Nation’s waters. In general, the NAWQA Program investigates 

those pesticides, nutrients, volatile organic compounds, and metals that have been or are 

currently used commonly in agricultural and urban areas across the Nation. A complete 

list of compounds studied is on the NAWQA Web site at http://water.usgs.gov/nawqa.

• Detection relative to risk—Compounds are measured at very low concentrations, often 

10 to 100 times lower than Federal or State standards and health advisories. Detection of 

compounds, therefore, does not necessarily translate to risks to human health or aquatic 

life. However, these analyses are useful for identifying and evaluating emerging issues, 

as well as for tracking contaminant levels over time.

• Multiple scales—Assessments are guided by a nationally consistent study design and 

uniform methods of sampling and analysis. Findings thereby pertain not only to water 

quality of a particular stream or aquifer, but also contribute to the larger picture of how 

and why water quality varies regionally and nationally. This consistent, multiscale 

approach helps to determine if a water-quality issue is isolated or pervasive. It also 

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

quality in the Nation’s diverse environmental settings. 
vi

Introduction to this Report

This report contains the major findings of a 1998–2001 assessment of water quality in the Great 

Salt Lake Basins. It is one of a series of reports by the National Water-Quality Assessment 

(NAWQA) Program that present major findings in 51 major river basins and aquifer systems 

across the Nation. 

In these reports, water quality is discussed in terms of local, State, and regional issues. Conditions in a particular basin or aquifer system are compared to conditions found elsewhere and 

to selected national benchmarks, such as those for drinking-water quality and the protection of 

aquatic organisms. 

This report is intended for individuals working with water-resource issues in Federal, State, or 

local agencies, universities, public interest groups, or in the private sector. The information will 

be useful in addressing a number of current issues, such as the effects of agricultural and urban 

land use on water quality, human health, drinking water, source-water protection, hypoxia and 

excessive growth of algae and plants, pesticide registration, and monitoring and sampling strategies. This report is also for individuals who wish to know more about the quality of streams 

and ground water in areas near where they live, and how that water quality compares to water 

quality in other areas across the Nation.

The water-quality conditions in the Great Salt Lake Basins summarized in this report are discussed in detail in other reports that can be accessed at http://ut.water.usgs.gov. Detailed technical information, data and analyses, collection and analytical methodology, models, graphs, and 

maps that support the findings presented in this report in addition to reports in this series from 

other basins can be accessed at the national NAWQA Web site http://water.usgs.gov/nawqa.

“Through the city itself flows 

an unfailing stream of pure, 

sweet water, which, by an 

ingenious mode of irrigation, 

is made to traverse each side 

of every street, whence it is 

led into every garden spot, 

spreading life, verdure, and 

beauty over what was heretofore a barren waste.”

—Howard Stansbury, 1849,

Captain, Corps Topographic Engineers, United States Army, from 

1852, Exploration and Survey of the 

Valley of the Great Salt Lake of Utah.

Bear River near Corinne, Utah.
Summary of Major Findings

1

Stream and River Highlights

Surface water sampled in the Great Salt Lake Basins 

Study Unit generally meets existing guidelines for drinking 

water and protection of aquatic life. Urban, agriculture, and 

mining land uses have affected water quality, as indicated by 

elevated concentrations of pesticides, volatile organic compounds (VOCs), nutrients, chloride, and trace elements in 

basins dominated by these land uses. 

• Water development and management have degraded 

the chemical and biological quality of some streams. 

Water of good quality in headwater areas often is 

diverted before reaching lower stream reaches known 

for poorer quality. Streams with minimal flow have 

elevated concentrations of nutrients, warm temperatures, and reduced habitat cover, which are difficult 

conditions for fish and other aquatic organisms to 

survive. (See pages 6 and 7)

• Concentrations of nitrogen were about 3 to 4 times 

higher in urban, agricultural, and mixed land-use settings than in undeveloped basins. Phosphorus concentrations exceeded the U.S. Environmental Protection 

Agency (USEPA) desired instream goal of 0.1 mg/L

(milligram per liter) for preventing nuisance plant 

growth in 12 of 27 streams sampled. (See page 10)

• Pesticides are widespread, detected in about 95 percent 

of the streams sampled. Concentrations of carbaryl, diazinon, and malathion exceeded guidelines 

for protection of aquatic life. Aquatic-life guidelines 

have been established for only 18 of the 49 pesticides 

detected. Pesticide concentrations were generally 

lower in streams in undeveloped and agricultural areas 

than in streams affected by urban land uses. (See pages 

12 and 13)

• Of the 27 organochlorine compounds for which samples were analyzed, 12 were detected in fish tissue and 

6 in streambed sediment. Two commonly detected compounds were PCBs and DDT. In fish samples, PCBs 

were detected at 8 sites, DDT at 13 sites. In sediment, 

PCBs were detected at two sites, and DDT compounds 

at four sites. Guidelines for fish-eating wildlife were 

Selected Indicators of Stream Water Quality

Pesticides

Nitrate

Trace elements

in sediment1

Small Streams Major Rivers

Urban Mixed

Land Uses

Agricultural

Trace elements

in tissue1

Total

phosphorus

Proportion of samples with detected concentrations greater than

or equal to national drinking-water standards and guidelines,

guidelines for protection of aquatic life or wildlife, or the national

goal for preventing nuisance plant growth

Proportion of samples with detected concentrations that do not

exceed drinking-water standards and guidelines, guidelines for

protection of aquatic life or wildlife, or the national goal for

preventing nuisance plant growth

Proportion of samples with no detections

1 Arsenic, mercury, and metals.

2 Insufficient data.

3 Organochlorine compounds, including DDT, PCBs, and chlordane.

Undeveloped

Organochlorines

in tissue3

2

2

2

2

2

2

2

2

Organochlorines

in sediment3

40�

41�

42�

112� 111�

Great

 Salt

 Lake

Provo

River

River Jordan

Bear

River

Salt

Lake

City

IDAHO WYOMING

UTAH

River

Bear

River

Weber

Utah

Lake

Bear

Lake

Bear

River

UINTA

MOUNTAINS

MOUNTAINS

WASATCH

Provo

Ogden

IDAHO

UTAH

WYOMING

C

Silver

50 MILES

50 KILOMETERS

0

0

Weber

River

Basin

Utah LakeJordan

River

Basin

Bear

River

Basin

Urban area

EXPLANATION

25

25

The Great Salt Lake Basins Study Unit encompasses about 14,500 

square miles and includes parts of northeastern Utah, southeastern 

Idaho, and southwestern Wyoming. The Study Unit comprises three 

major river systems that enter Great Salt Lake: the Bear, Weber, and 

Utah Lake–Jordan River systems. About 1.7 million people, or about 

76 percent of the population in the State of Utah, live along the western flanks of the Wasatch Mountains in the Salt Lake City, Ogden, and 

Provo metropolitan areas. 
2 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

exceeded for total DDT (2 sites) and PCBs (4 sites). 

The use of most of these compounds has been discontinued for decades, but they continue to persist in the 

environment. (See page 18)

• At 9 of 15 sites sampled for streambed sediment and 

11 of 14 sites sampled for fish tissue, concentrations of 

at least 1 trace element were greater than 90 percent of 

the samples collected in all NAWQA studies nationally in 1993–2000. Aquatic-life guidelines for arsenic, 

cadmium, copper, lead, mercury, silver, and zinc were 

exceeded in bed-sediment samples from stream reaches 

that were affected by mine tailing deposits and smelters 

(including some on urbanized streams). (See pages 21 

and 24)

Ground-Water Highlights

Ground water is a major source of public supply in the 

Great Salt Lake Basins Study Unit. The basin-fill aquifers 

receive recharge from precipitation on the mountains through 

subsurface inflow and from infiltration of precipitation, 

irrigation, or seepage from streams and canals in the valleys. 

Shallow ground water in Salt Lake Valley contains elevated 

concentrations of nitrate; and pesticides and VOCs were 

detected in many samples from the shallow aquifer, indicating that the shallow aquifer is affected by human activities at 

the land surface. Water from the deeper underlying basin-fill 

aquifers generally meets existing Federal and State standards 

and regulations for drinking water. 

• The median nitrate concentration of 6.8 mg/L for 

shallow water from 30 monitoring wells in recently 

developed residential and commercial areas in Salt 

Lake Valley is the highest of 34 studies done across the 

Nation as part of the NAWQA Program. These wells 

are in areas with high potential for downward movement of water to the underlying basin-fill aquifer used 

for public supply. (See page 11)

• Tetrachloroethene (PCE) was detected more frequently 

in shallow ground water underlying residential and 

commercial areas in Salt Lake Valley than in most 

ground water sampled by NAWQA across the Nation. 

PCE was detected in water from 16 of 30 monitoring 

wells. Water from one monitoring well exceeded the 

USEPA drinking-water standard of 5 μg/L (micrograms 

per liter) for PCE, although water from the shallow 

aquifer is not used for drinking. (See pages 14 and 15) 

• VOCs were frequently detected in water from the 

basin-fill aquifers in both agricultural and urban areas. 

Chloroform, likely formed as a byproduct of water disinfection, was the most frequently detected VOC, but 

at concentrations much less than the USEPA drinkingwater standard. (See page 15)

• Atrazine was the most frequently detected pesticide 

(77 percent of samples) in shallow ground water underlying Salt Lake Valley, but mostly at concentrations 

much less than the USEPA drinking-water standard of 

3 μg/L. Atrazine was detected in 23 percent of samples 

collected from wells in the basin-fill aquifers throughout the Study Unit. (See page 15) 

• The age (time since recharge) of water from 31 publicsupply wells in Salt Lake Valley ranged from 3 to more 

than 50 years. Manmade compounds generally were 

detected in water that was less than 50 years old, but 

not in water more than 50 years old. (See page 16)

• Concentrations of arsenic in water from about 20 percent of wells (primarily domestic wells) in the basinfill aquifers underlying recharge areas exceeded the 

USEPA drinking-water standard of 10 μg/L. Arsenic in 

basin-fill aquifers likely is derived naturally from geochemical reactions between aquifer minerals and water. 

(See page 21)

Selected Indicators of Ground Water Quality

Pesticides

Nitrate

Arsenic

Volatile

organics1

Radon

Proportion of samples with detected concentrations greater than

or equal to health-related national guidelines for drinking water

Proportion of samples with detected concentrations less than

health-related national guidelines for drinking water

Proportion of samples with no detections

1 Solvents, refrigerants, fumigants, and gasoline compounds.

Shallow Ground Water

Urban

Deeper Aquifers

Water-Supply Wells

Mixed Land Use

 Major Influences on Streams and Rivers 

• Urban and agricultural land use

• Historical mining activities

• Water development and management

 Major Influences on Ground Water 

• Urban and agricultural land use

• Aquifer properties and characteristics

• Sources of ground-water recharge
Introduction to the Great Salt Lake Basins

3

Figure 1. Large changes in altitude, climate, and land use produce a wide range of hydrologic environments in the Great Salt Lake 

Basins. 

Physical Setting and Climate

The Great Salt Lake Basins Study 

Unit includes about 14,500 square 

miles of northeastern Utah, southeastern Idaho, and southwestern Wyoming 

and three major river systems that enter 

Great Salt Lake: the Bear, Weber, and 

Utah Lake-Jordan River systems (Baskin 

and others, 2002). Altitude ranges from 

about 4,200 feet near Great Salt Lake 

to more than 12,000 feet in the Uinta 

Mountains near the eastern edge. About 

1.7 million people or about 76 percent of 

the population in the State of Utah (2000 

census) live along the western flanks of 

the Wasatch Mountains, where Utah’s 

largest cities are located (fig. 1).

The climate in the Study Unit is 

typical of mountainous areas in the 

Western United States. Temperature 

generally fluctuates widely between 

summer and winter and between day and 

night. The high mountains have long, 

cold winters and short, cool summers. 

The lower valleys are more moderate, 

with less variance between maximum 

and minimum temperatures. Average 

monthly maximum temperature reaches 

92oF in July at the Salt Lake City 

International Airport, and the average 

monthly minimum reaches –1.5oF in 

January at Sage, Wyoming.

Most of the annual precipitation 

falls as snow, which provides most of 

the annual runoff during the spring as 

snowmelt. Average annual precipitation 

ranges from less than 16 inches on the 

valley floors to greater than 70 inches in 

the high mountain areas.

40�

41�

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112� 111�

Great

 Salt

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Provo

River

River Jordan

Bear

River

Salt

Lake

City

IDAHO WYOMING

UTAH

River

Bear

River

Weber

Utah

Lake

Bear

Lake

Bear

River

River

Malad

Bear

River

Basin

Weber

River

Basin

Utah LakeJordan

River

Basin

River

Weber

UINTA

MOUNTAINS

WASATCH

MOUNTAINS

Creek

Silver

Provo

Ogden

Along the western front of the Wasatch

Mountains, urbanization extends across

valleys onto flanks of mountains that

provide ground- and surface-water

supplies

Many urban streams have been diverted

and channeled around manmade features

High mountain wetlands are common

in headwaters along the western front

of the Wasatch Mountains

Historical mining activities left metal-laden tailings

deposits in the upper Weber River and Utah LakeJordan River drainage basins

Vast rangelands occur in the upper drainage of

the Bear River Basin

The upper reaches of the Bear River are generally

unregulated

Park

City

0 20 40 60 KILOMETERS

0 20 40 60 MILES
4 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

Hydrologic Conditions

Total average annual surface-water 

discharge from the three river systems 

during 1931–76 was 2.98 million acrefeet. Of this total, about 62 percent was 

discharged by the Bear River Basin, 

23 percent by the Weber River Basin, 

and 15 percent by the Utah Lake-Jordan River Basin (fig. 2) (Waddell and 

Barton, 1980). 

Streamflow variability results 

from seasonal variations of precipitation, temperature, and evapotranspiration, and human-induced hydrologic 

modifications resulting from dams and 

diversions. Flows in most of the major 

streams and tributaries naturally peak 

during May to June (fig. 3). 

In some watersheds, dams that create major reservoirs control streamflow. 

The basins have 27 reservoirs with a 

storage capacity greater than 6,500 acrefeet, resulting in a combined storage 

capacity of more than 3.5 million acrefeet. This includes Bear Lake, which 

has a usable storage capacity of about 

1.4 million acre-feet, much of which 

comes from water diverted from the 

Bear River (fig. 4). Snowmelt is stored 

in reservoirs (usually during March 

through June) and is released during the 

irrigation season (June through September). The regulation alters the basin’s 

natural peak runoff period and affects 

the physical, chemical, and biological 

conditions of streams.

Water Use

Irrigation is the primary use of 

water in the Great Salt Lake Basins 

study unit. In 1995, irrigation for 

agriculture accounted for an estimated 

92 percent of all water use in the Bear 

River Basin, 82 percent in the Weber 

River Basin, and 70 percent in the Utah 

Lake-Jordan River Basin. Water use for 

public supply was estimated at 4 percent 

(of all use) in the Bear River Basin, 

16 percent in the Weber River Basin, 

and 26 percent in the Utah Lake-Jordan 

River Basin. 

Total water use in the Great Salt 

Lake Basins Study Unit in 1995 was 

estimated to be 2,797 Mgal/d (million gallons per day) (U.S. Geological 

Survey, 1995). About 2,379 Mgal/d 

(85 percent) of this total was supplied 

by surface-water withdrawals and 418 

Mgal/d (15 percent) by ground-water 

withdrawals. Irrigation accounted for 

about 2,130 Mgal/d in surface-water 

withdrawals and 139 Mgal/d in groundwater withdrawals. An estimated 193 

Mgal/d of surface water and 240 Mgal/d 

of ground water were withdrawn for 

public supply.

Water Quality and Land Use

As the major rivers emerge from 

the headwater areas and flow through the 

broad valleys east of the Wasatch Mountains, water quality is similar among 

the three rivers, controlled primarily by 

natural factors. At lower altitudes west 

of the Wasatch Mountains, however, 

and to a lesser extent in the areas east of 

and adjacent to the Wasatch Mountains, 

human and natural factors differ considerably and affect the rivers in different 

ways.

Natural factors of physiography, 

geology, soils, climate, and hydrology 

largely determine the natural background quality of water, and cultural 

factors of population, land and water 

use, and water- and waste-management 

practices define the human influence 

on water quality. Hydrologic modifications of streams, along with point and 

nonpoint sources of contaminants, have 

had detrimental effects on the quality of ground-water and surface-water 

Figure 2. Total average annual surfacewater discharge from the three river 

systems during 1931–76 was 2.98 million 

acre-feet. 

Bear River

1.85 million

acre-feet

per year

Weber River

0.68 million

acre-feet

per year

Utah LakeJordan River

0.45 million

acre-feet

per year

23%

62% 15%

0

500

1,000

1,500

2,000

2,500

Streamflow

Average streamflow

75th percentile

25th percentile

1,000

2,000

3,000

STREAMFLOW, IN CUBIC FEET PER SECOND 4,000

0

0

1998 1999 2000 2001

1,000

2,000

3,000

4,000

5,000

6,000

7,000

Jordan River at Salt Lake City, Utah

Weber River near Plain City, Utah

Bear River near Corinne, Utah

Figure 3. Flow in most streams in the 

study area was above normal during the 

1999 water year, then below normal during 

water years 2000–01. 

0

0 25 50 KILOMETERS

25 50 MILES

River

River

River

Provo

River

Jordan River

Spanish

Fork

Utah

Lake

Salt

Lake

City

Bear

Bear

River

Bear

Weber

Bear

Lake

IDAHO

WYOMING

Great

 Salt

 Lake

UTAH

40�

41�

42�

112� 111�

EXPLANATION

Capacity, in acre-feet

6,500 to 20,000

20,000 to 50,000

50,000 to 100,000

100,000 to 250,000

250,000 to 1,000,000

More than 1,000,000

Figure 4. Reservoir capacity in the Great 

Salt Lake Basins Study Unit exceeds 3.5 

million acre-feet.
Introduction 5

resources throughout the basins (Utah 

Department of Natural Resources, 

1996).

Rangeland covers about 48 percent 

of the Study Unit and forest and agricultural land covers 22 and 18 percent, 

respectively (Hitt, 1994). Urban land 

accounts for 4 percent of the total land 

cover, and the remaining 8 percent is 

distributed between wetlands (4 percent), water (3 percent), and bare ground 

(1 percent) (fig. 5). Mining occurred in 

several of the canyons of the Wasatch 

Mountains within a 30-mile radius of 

Salt Lake Valley. 

Land use and associated human 

activities alter the natural character of 

streams by changing water quality, channel shape, and flow characteristics. In 

headwater areas, logging, mining, and, 

more recently, recreation and residential 

construction have increased erosion and 

changed water quality. In the valleys, 

agriculture, grazing, and urbanization 

have removed many of the natural wetlands and riparian vegetation; channel- ized stream reaches in some areas; and 

contributed nutrients, sediments, and 

other contaminants to streams.

Aquatic Habitat and Biota

The composition of aquatic 

communities depends on stream environment. The distribution of aquatic 

invertebrates and algae is determined 

by local habitat characteristics such as 

substrate size and type, stream velocity, 

food source availability, and water temperature (Stevenson and others, 1996). 

In the Study Unit, these physical factors 

vary considerably between small, steep 

mountain streams and large, lowgradient streams. 

 The native fishery of the basin 

is limited in diversity and has been 

affected by introductions of nonnative 

fish. Trout are the dominant species

in cold waters at higher altitudes, and 

introduced warm-water fishes dominate 

in warmer waters at lower altitudes 

(Holden and others, 1996). At least 20 

exotic species are common to streams in 

the Study Unit.

Ground Water

Ground water is contained within 

unconsolidated basin-fill deposits in 

the basins and in consolidated rocks in 

the mountains (fig. 6). The unconfined 

part of the basin-fill aquifers, which is 

the primary recharge area, contains the 

water table (or uppermost saturated zone 

in the subsurface) and is the most vulnerable to contamination from overlying 

land-use activities. The lack of confining

layers near the mountain fronts results 

in relatively deep unconfined aquifers 

(water levels generally greater than 

100 feet below land surface). Mountainfront areas are becoming increasingly 

developed for residential and commercial uses. Where confining layers exist in 

the subsurface, shallow unconfined aquifers (generally about 50 feet below land 

surface) overlie the confined aquifers 

(Thiros, 2003a). Water from the adjacent and overlying unconfined deposits 

recharges confined parts of the basin-fill 

aquifers. Although separated from the 

land surface by confining layers, the 

confined aquifers also are susceptible 

to contamination from the shallow and 

deeper unconfined aquifers by flow 

reversals caused by large withdrawals 

of ground water. The basin-fill aquifers 

are a major source of water for domestic 

and municipal supply and for irrigated 

agriculture. 

Figure 5. Land-use/land-cover information is useful in assessing human 

influences on water quality by providing 

information on the possible causal factors 

related to water-quality observations.

Figure 6. Ground water in the study area generally comes from precipitation on the 

mountains or on valley benches, where it infiltrates into the soil and moves to the 

basin-fill aquifers. 

Great

 Salt

 Lake

Salt

Lake

Valley

EXPLANATION

25 50 MILES

0 25 50 KILOMETERS

0

111�

River

112�

UTAH

IDAHO

WYOMING

Bear

42�

River

Bear

River

Weber

Salt Lake City

Jordan

River

Provo

River

Urban 40�

Agricultural

Rangeland

Forest

Water

Wetland

Salt flats/exposed rock

Bare ground

41�

Bear

Lake

Utah

Lake

Basin-fill deposits of

Tertiary age

Great Salt Lake

Consolidated

rock

Water level

in shallow

aquifer

Water level in deeper

aquifer

Shallow

aquifer

Confining layer

Primary

recharge area

Secondary

recharge area

Discharge area

EXPLANATION

Direction of ground-water movement

Coarse-grained

deposits

Basin-fill deposits of

Quaternary age

Deeper

basin-fill

aquifer
6 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

Major Findings

Water development 

affects quantity and 

quality of water 

resources 

Streamflow regulation, such 

as that in the Bear River Basin, 

alters daily and seasonal flows 

Regulation of streamflow for power 

generation and irrigation substantially 

alters daily flow in some streams in the 

Great Salt Lake Basins Study Unit. For 

example, streamflow in the Bear River 

at the Utah/Idaho State line, downstream 

from the Oneida Narrows hydroelectric 

dam, fluctuated from about 400 to more 

than 1,600 ft3/s (cubic feet per second) 

over a 7-day period in August 2000. 

Flow in the Bear River near Cokeville, 

Wyoming, which is not affected by 

power generation, remained nearly constant at 180 ft3/s during the same period 

(fig. 7). 

Seasonal fluctuations in flow in a 

regulated stream in the basins also are 

demonstrated in the Bear River. During 

the winter months, when large amounts 

of water are not stored in reservoirs 

or diverted into canals, flow naturally 

increases in a downstream direction 

(from about 50 to more than 1,000 ft3/s) 

(fig. 8). In the summer months, when 

water is released from reservoirs and 

diverted into canals for irrigation, flow 

changes substantially (from nearly no 

flow in some stream segments, to more 

than 1,200 ft3/s in others) (fig. 8). 

Periodic low flow in streams can 

affect recreation, ground-water recharge, 

aquatic life, and fish and wildlife 

habitat. To avoid such effects, minimum 

instream flow requirements, maintained through purchased water rights 

or legislation, have been established for 

some streams in the Great Salt Lake 

Basins. Segments of other streams with 

no requirements, including some in the 

Bear River Basin, however, can be completely dewatered by diversions.

Reductions in water quantity 

also affect water quality in 

streams 

Identifying and understanding daily 

and seasonal fluctuations in streamflow 

is important because the amount of 

water in a stream can directly affect 

the quality of the water. Specifically, 

the magnitude and timing in transport of sediment, nutrients, and other 

contaminants is affected. For example, 

concentrations of total phosphorus in 

the Bear River in March 2001, when 

flow regulation was minimal, increased 

downstream from less than 0.004 mg/L 

at the Utah/Wyoming State line (near the 

Figure 7. During a typical week in 

the summer, streamflow at sites below 

hydroelectric dams (such as Bear River 

at Utah/Idaho State line) have large daily 

fluctuations, while sites unaffected by 

power generation (such as Bear River near 

Cokeville) have steady flow. 

0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

Bear River at Utah/Idaho State line

Bear River near Cokeville

1

STREAMFLOW, IN CUBIC FEET

PER SECOND

TYPICAL DAYS IN AUGUST 2000

2 3 4 5 6 7

Figure 8. The flow of the Bear River in 

February approaches that of a natural 

river, increasing from upstream to downstream. The flow in August is dramatically 

altered by release and diversion of stored 

water for downstream irrigators.

0

400

800

1,200

1,400

February 2001

August 2001

STREAMFLOW, IN CUBIC FEET PER SECOND

0 100 300 400 500 Cutler Reservoir Mud Lake/Bear Lake Black Canyon200

MILES DOWNSTREAM FROM HEADWATERS

200

600

1,000

Idaho Wyoming

Utah

Bear

River

Salt

Lake

City

41�

42�

112� 111�

Bear

River

IDAHO

UTAH

Bear

Lake

Bear

River

EXPLANATION

Bear

River

41�

42�

112� 111�

Bear

River

IDAHO

UTAH

Bear

Lake

Bear

River

WYOMING

WYOMING

Total phosphorus concentration, 2001

Low (less than 0.05 milligrams per liter)

Moderate (0.05 to 0.099 milligrams per liter)

High (0.1 milligrams per liter or greater)

Dam

March July/August

Bear River

headwaters

0 20 40 MILES

0 20 40 KILOMETERS

Figure 9. In the Bear River, contributions from tributary streams have a large influence 

on total phosphorus concentration in March. Reservoir management and canal diversions affect concentrations in July and August.
Major Findings 7

headwaters) to 0.49 mg/L below Cutler 

Reservoir (near the mouth) (fig. 9). 

Concentrations of phosphorus in the 

contributing tributaries averaged about 

0.46 mg/L and were associated primarily with natural phosphorus deposits, 

manure from animal feeding operations, fertilizers used on farm fields, 

and wastewater-treatment discharge. In 

contrast, concentrations of total phosphorus in the Bear River in July/August 

2001, when large amounts of water were 

diverted for irrigation, were highly variable, especially above and below dams. 

For example, concentrations of total 

phosphorus generally increased below 

reservoirs upstream from Bear Lake 

(possibly due to low water levels in the 

reservoirs, which allowed resuspension 

of particulate phosphorus) and decreased 

below most reservoirs downstream from 

Bear Lake (due to deposition of particulate phosphorus in the reservoirs). 

During this period, tributaries generally 

were diverted upstream from their confluence with the Bear River and contributed little flow or contaminants to the 

Bear River.

Similar patterns in water quality 

above and below diversions also were 

noted in other streams (fig. 10). In general, streams above diversions generally drain undeveloped basins and water 

is of good quality. Below diversions, 

streamflow consists mainly of agricultural and urban runoff, ground-water 

inflow, and inflow from irrigation canals 

and wastewater-treatment facilities, 

which can contain elevated levels of 

suspended sediment, nutrients, organic 

pollutants, and dissolved solids. For 

example, the concentration of dissolved 

solids above diversions on Baer Creek, 

a small stream in the Weber River Basin 

between Ogden and Salt Lake City, was 

less than 100 mg/L, whereas the concentration below diversions was greater 

than 500 mg/L.

Fish communities in urban 

streams respond to changes in 

water quantity

Water management infrastructure 

and operation affect fish community 

composition and the ability of urban 

streams to support fish. These factors are 

particularly important in moderate-sized 

watersheds, such as Little Cottonwood, 

Big Cottonwood, and Mill Creeks in Salt 

Lake Valley, Utah. These watersheds are 

similar in size and environmental setting 

but have very different fish communities, in large part due to withdrawals of 

water. Water is withdrawn from Little 

and Big Cottonwood Creeks before 

they flow into urban areas, sometimes 

resulting in complete dewatering of the 

channel below the withdrawal point in 

the summer, when natural flows are low 

(fig. 11). In Mill Creek, smaller diversions remove water, but there is not a 

large withdrawal that completely dewaters the channel. Water is restored to all 

three stream channels downstream from 

diversions through ground-water inflow 

and additions through canal systems. 

The additions to Big Cottonwood Creek 

are more substantial than those to Little 

Cottonwood Creek, and as a result, flow 

in Big Cottonwood Creek is more nearly 

continuous and reliable in the summer.

Fish communities in these streams 

reflect the differences in flow. For example, in Little Cottonwood Creek, which 

had the largest diversions and least flow, 

the fish community consisted of mountain sucker, speckled dace, and fathead 

minnows. These small-bodied fish are 

able to survive in low-flow, shallower 

environments. In Mill Creek, which had 

the least diversion and most flow, the 

dominant fish collected was brown trout, 

a larger species. The fish community 

of Big Cottonwood Creek was a mix of 

mountain sucker (the dominant fish species in Little Cottonwood Creek), brown 

trout, and a variety of other species consisting primarily of sunfishes, minnows, 

and catfish (fig. 12).

Alterations of natural flow in 

stream channels can adversely affect 

water quality and the availability and 

quality of fish habitat. Consequently, 

Figure 11. Segments of many urban 

streams in the Study Unit, such as the one 

shown here on Little Cottonwood Creek, 

are completely or nearly dewatered in the 

summer when natural flows are low and 

water use is high.

CONCENTRATION,

IN MILLIGRAMS PER LITER

Dissolved solids

0

100

200

300

400

500

600

700

Kays

Creek

Baer

Creek

Nitrite+nitrate

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Above

diversion

Below

diversion

Kays

Creek

Baer

Creek

Figure 10. Good quality water from 

undeveloped basins is diverted at canyon 

mouths. Agricultural and urban runoff 

replaces this water, and the quality of 

water in the stream is degraded.

Dominant fish

0 10 20 14 18 0.10 0.20 0.30

Big

Cottonwood

Creek

Little

Cottonwood

Creek

Mill Creek

DISSOLVED ORGANIC

NITROGEN, IN MILLIGRAMS PER LITER

AVERAGE SUMMER

TEMPERATURE, IN

DEGREES CELSIUS

5 15 25 12 16 20 0.5 0.15 0.25

STREAMFLOW, IN

CUBIC FEET

PER SECOND

Figure 12. Among three sampled urban streams, the two with lower streamflow 

(and greater withdrawals) had warmer water temperatures and poorer water 

quality (shown by higher concentrations of dissolved organic nitrogen) and were 

dominated by smaller fish species.
8 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

changes in natural flow conditions can 

result in corresponding changes in the 

number and kinds of fishes found in a 

stream. For example, streams with more 

diversions have less available habitat for 

fish. With decreased water at low flows, 

deeper water habitats, such as pools, are 

reduced, which limits larger species, 

such as brown trout. Smaller species that 

are adapted to shallow, riffle areas, such 

as mountain sucker, tend to dominate in 

streams with severe dewatering. In addition, streams with less flow had higher 

water temperatures and higher concentrations of nutrients. These conditions 

tend to favor warm-water fish species 

more tolerant of high temperatures and 

degraded water quality, such as sunfish 

and catfish. 

Pumping likely affects the 

distribution of dissolved solids 

in the basin-fill aquifer in Salt 

Lake Valley 

Pumping from wells accounts for 

about one-third of the total estimated 

discharge from the basin-fill aquifer in 

Salt Lake Valley, Utah, an urban area in 

the Study Unit (seepage to streams and 

evapotranspiration are the other major 

forms of discharge). Most ground-water 

withdrawals occur on the eastern side of 

the valley because of higher well yields 

(discharge rates) and lower dissolvedsolids concentrations. In some areas 

on the western side, ground water is 

withdrawn and blended with water from 

other sources to improve its quality.

Comparison of water in the basinfill aquifer sampled in 1988–92 and 

that sampled in 1998–2002, shows an 

increase in the extent of the aquifer 

containing water with a dissolved-solids 

concentration greater than 500 mg/L. 

Water with less than 500 mg/L dissolved 

solids extended to the northwest past 

the Jordan River in 1988–92, but was 

replaced by water with concentrations of 

dissolved solids greater than 500 mg/L 

by 1998–2002 (fig. 13). Concentrations 

of dissolved solids increased in water 

from some wells near the center of the 

valley, where the direction of groundwater movement (gradient) is naturally 

upward between the basin-fill aquifer 

and land surface. Withdrawals from the 

basin-fill aquifer for public supply may 

have caused gradients to reverse, allowing more mineralized water that was 

recharged in the valley to move to the 

aquifer.

Land use influences 

water quality and aquatic 

community health

Undeveloped basins show 

minimal degradation of water 

quality and biological 

communities

Water quality and biological conditions are generally better in streams 

draining forests and rangeland (undeveloped areas) than in streams draining 

agricultural and urban areas or areas of 

mixed land use (developed areas).

In the State of Utah, the criterion for water temperature in stream 

reaches designated to support coldwater aquatic life is 20 degrees Celsius (oC). This criterion was selected 

prior to any continuous monitoring 

of stream temperature and applies to 

any point measurement of temperature 

taken at any time of day. Twenty-one 

sites on 13 urban streams designated 

to support cold-water game fisheries 

were monitored for temperature, and 

at 17 of these sites the criterion was 

exceeded at least once during the summer of 2000. Five sites had maximum 

daily temperatures that exceeded the 

criterion on more than 75 percent of 

the days during this time. 

Most urban sites are in the 

valley and are exposed to warmer 

air temperatures; however, these 

streams historically supported coldwater salmonid species (Sigler and 

Sigler, 1996). Thermal pollution 

in these streams is likely due to 

upstream diversion of water and 

subsequent replacement with urban 

and agricultural runoff. Additionally, the reduction of flow that also 

results from diversions increases 

temperatures during the summer 

due to the loss of thermal mass. 

Increased temperatures in 

urban streams have changed fish 

communities. Specifically, warm-water 

species, such as common carp, green 

sunfish, and channel catfish, which are 

not native to streams in the Great Salt 

Lake Basins, have populated streams 

in which temperatures exceed 20oC 

at least 30 percent of the time. These 

warm-water species have replaced 

native cold-water species, such as trout 

and whitefish, and cool-water species, 

such as sculpin and dace, which cannot tolerate the warmer waters. In fact, 

in streams where the daily maximum 

temperature exceeds 20oC more than 

75 percent of the time, cold-water species compose less than 25 percent of 

the fish community.

Upstream diversions have resulted in 

increased water temperatures in streams 

and changed fish communities 

PERCENTAGE OF DAYS THAT MAXIMUM TEMPERATURE

EXCEEDED CRITERIA DURING JUNE-AUGUST 2000

PERCENTAGE OF SPECIES 100

75

50

25

0 0 Percent 0 to 30

Percent 30 to 75Percent 75 to 85Percent

Warm-water

species

Cool-water

species

Cold-water

species
Major Findings 9

Forest and rangeland cover 

approximately 70 percent of the Study 

Unit. Undeveloped basins are sparsely 

populated and commonly include high, 

precipitous mountains with narrow 

crests and forested valleys or broad 

intermontane basins dominated by arid 

grasslands and shrublands. Examples of 

streams in undeveloped areas include the 

upper Bear and upper Weber Rivers, and 

Red Butte Creek (Jordan River Basin). 

The quality of water and the state of the 

aquatic community in these streams represents “natural” conditions in the basins 

(fig. 14).

The concentration of dissolved 

solids in a stream generally indicates 

the degree of stream development and 

human influence on water quality. For 

example, concentrations in undeveloped 

streams ranged from 176 to 469 mg/L, 

whereas concentrations in more developed and urbanized streams ranged from 

67 to 2,750 mg/L (fig. 15). Elevated 

concentrations of dissolved solids in the 

developed streams generally reflect the 

return of water to the streams after use 

for human consumption, industrial activities, and irrigation.

Physical habitat, including streambed composition, bank stability, water 

velocity and depth, amount of sunlight 

received, and protective structures also 

indicates the degree of stream development and human influence. Physical habitat features often are integrated 

into one measure, referred to as Habitat 

Quality Index Scores, which were higher 

(better) for undeveloped streams than 

for developed streams (fig. 15). Streams 

with dams and diversions sometimes had 

lower scores regardless of human influences or land-use activities within their 

basins. For example, the watershed above 

the Bear River near Pescadero, Idaho, is 

largely undeveloped; the Habitat Quality Index Score in this stream reach is 

low, however, because channelization 

and flow regulation have resulted in little 

pool variation or stream sinuosity. 

Composition of biological communities also indicates degree of stream 

development and human influence. 

Specifically, streams in developed basins 

had aquatic communities that were 

more tolerant to pollution and habitat 

disturbances than were aquatic communities in undeveloped basins. Streams 

in developed basins also had a lower 

percentage of native fish species such 

as longnose dace and cutthroat trout, a 

lower percentage of insect taxa preferring good water-quality conditions such 

as mayflies, stoneflies, and caddisflies, 

and a higher percentage of pollutiontolerant algal species, such as Nitzschia 

inconspicua.

2,500

2,000

1,500

1,000

500

0

DISSOLVED SOLIDS, IN

MILLIGRAMS PER LITER

3,000

Sensitive Tolerant

POLLUTION TOLERANCE INDEX, ALGAL

SITE GROUP

HABITAT QUALITY INDEX SCORE140

80

100

120

160

60

40

Median

Undeveloped Developed Undeveloped Developed0

PERCENTAGE OF NATIVE FISH SPECIES NUMBER OF STONEFLY, MAYFLY,

AND CADDISFLY SPECIES

100

80

60

40

20

0

Affected

by habitat

degradation

15

10

5

Figure 15. Aquatic communities and 

water chemistry in streams affected by 

urban and agricultural land uses are generally degraded compared to streams in 

largely undeveloped basins with predominantly rangeland and forest land cover.

Figure 14. USGS scientists assess stream 

habitat at a site on the upper Weber River 

(a largely undeveloped river basin).

Figure 13. Dissolved-solids concentration in water from parts of the deeper basin-fill 

aquifer in Salt Lake Valley increased from 1988–92 to 1998–2002.

EXPLANATION 0 3 6 KILOMETERS

0 3 6 MILES

Great Salt Lake

40� 30'

40� 45'

Jordan River

112�07'30" 111�48'

Great Salt Lake

40�

30'

40�

45'

Jordan River

112�07'30" 111�48'

Dissolved-solids concentration, in milligrams per liter, 1988–1992 and 1998–2002

Less than 250 250 to 500 500 to 1,000 Greater than 1,000

1988–1992 1998–2002

Approximate boundary of basin-fill deposits in Salt Lake Valley

OQUIRRH MOUNTAINS

WASATCH MOUNTAINS

Salt

Lake

City

Salt

Lake

Valley

OQUIRRH MOUNTAINS

WASATCH MOUNTAINS

Salt

Lake

City

Salt

Lake

Valley
10 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

Phosphorus and nitrogen 

levels are elevated in streams 

draining agricultural and urban 

areas 

Streams associated with agricultural, urban, or mixed land uses generally had higher concentrations of phosphorus and nitrogen relative to streams 

associated with forest or rangeland 

cover. 

Nutrients occur naturally in streams 

due to mineral weathering and biological activity in the streambed sediment; 

however, additional nutrients can enter 

streams in agricultural and urban runoff, 

atmospheric deposition, and wastewater 

discharge. Elevated nutrients can lead 

to eutrophic conditions, which include 

excessive growth of aquatic vegetation, 

reduced dissolved-oxygen concentrations, imbalance of predator and prey 

species, and a decline in aesthetic and 

recreational values. 

Concentrations of phosphorus 

exceeded the USEPA desired goal of 

0.1 mg/L to prevent nuisance plant 

growth in streams in only 15 percent of 

the samples from undeveloped streams 

(fig. 16). More than 80 percent of the 

samples from streams affected by agricultural and mixed land use had phosphorus concentrations exceeding 

0.1 mg/L. Total phosphorus concentration in water from urban streams 

exceeded 0.1 mg/L in only 21 percent 

of the samples; however, the highest concentrations of total phosphorus were measured in water samples 

from urban sites on Silver Creek (2.49 

mg/L, attributed to treated wastewater 

outflow) and Little Cottonwood Creek 

(2.39 mg/L, attributed to storm runoff). 

Concentrations of nitrogen were 

higher in streams in basins with predominately agricultural, urban, or 

mixed land uses, relative to streams in 

undeveloped watersheds. The median

concentration of total nitrogen measured 

in water samples from undeveloped 

streams was 0.37 mg/L (fig. 16). This is 

within the range of total nitrogen concentrations representing naturally occurring (or “reference”) conditions 

(0.34 – 0.48 mg/L) identified by the 

USEPA (2000) for the ecoregions in 

which the Study Unit resides. The 

median concentration of total nitrogen 

was above the reference range in water 

samples from urban (1.1 mg/L), agricultural (1.7 mg/L), and mixed-land-use 

streams (1.8 mg/L).

Urban, agricultural, and mixed 

land-use streams with elevated concentrations of phosphorus and nitrogen 

are contributing nutrients to lakes and 

reservoirs in the Study Unit, sometimes 

resulting in eutrophication of these 

water bodies. For example, Pineview 

and East Canyon Reservoirs in the 

Weber River Basin have been shown 

to have seasonal depletion of dissolved oxygen because of algal blooms 

associated with excessive amounts of 

nutrients. Less dissolved oxygen in 

these reservoirs negatively affects the 

fish community. These reservoirs and 

their respective watersheds are being 

managed to control nutrients, including 

the amount of nutrients introduced by 

streams.

Nitrate levels generally are 

low in the basin-fill aquifers 

Concentrations of nitrate in water 

from the basin-fill aquifers used for 

water supply throughout the Study Unit 

generally were low—at or less than 

2 mg/L—which is considered a naturally 

occurring or “background” concentration on the basis of available data for 

undeveloped areas across the Nation 

(U.S. Geological Survey, 1999). Only 

four samples exceeded the USEPA 

drinking-water standard for nitrate 

(10 mg/L). Water from these four wells 

is used for irrigation and stock watering, 

and not for drinking. The highest measured concentration of nitrate 

(27.9 mg/L) was in a sample from a well 

in an agricultural area (fig. 17).

The presence of clay confining 

layers between the land surface and the 

basin-fill aquifers impedes the movement of water and any included contaminants to the underlying aquifer. The 

median concentration of nitrate in water 

from the confined part of the basin-fill 

aquifers was 1.5 mg/L. Concentrations 

of nitrate were highest in wells in the 

primary recharge areas (fig. 6) of the 

basin-fill aquifers (relative to wells in 

the more downgradient, confined parts). 

Specifically, the median concentration 

of nitrate was 3.1 mg/L in the primary 

recharge areas of the aquifers, which 

was the seventh highest value for 94 

major drinking-water aquifers studied by 

NAWQA across the Nation. 

Figure 16. The concentration of 

phosphorus and nitrogen in undeveloped 

(forest/rangeland) streams was generally 

lower than in streams affected by other 

land uses. 

Urban

Mixed

Agriculture

Undeveloped

Urban

Mixed

Agriculture

Undeveloped

Median

Desired goal for preventingnuisance plant growth

2.5

2.0

0

1.5

1.0

0.5

CONCENTRATION, IN MILLIGRAMS PER LITER

TOTAL

PHOSPHORUS

TOTAL

NITROGEN

STREAM TYPE

12

8

2

0

4

6

10

14

16

NITRATE CONCENTRATION, IN MILLIGRAMS PER LITER 25

20

0

15

10

5

30

Rangeland Agricultural Urban

Shallow

aquifer,

not used

for water

supply

USEPA

drinking-water standard

Urban

Deeper basin-fill aquifers,

used for water supply

National background level

Data set median

DOMINANT LAND USE SURROUNDING

SAMPLED WELLS

Figure 17. The median nitrate concentration of ground-water samples collected 

from the deeper aquifers is lower than the 

median for samples from a shallow aquifer in an urban area. Nitrate in most wells 

is below the drinking-water standard.
Major Findings 11

Although none of the sampled 

domestic-supply wells in the basin-fill 

aquifers contained nitrate at concentrations that exceeded the drinking-water 

standard, the elevated concentrations 

(above background) indicate that the 

basin-fill aquifers are susceptible to 

human activities at the land surface. A 

chemical analysis of the water is generally required before a domestic-supply 

well can be connected to a residence, 

but subsequent monitoring typically is 

not required. It may be important for 

domestic well owners to assess activities around their wells and to monitor 

nitrate in their wells if concentrations 

are elevated or changing.

Urban storm runoff affects 

stream chemistry and 

temperature

Storm runoff can carry substantial 

quantities of nutrients, pesticides, and 

VOCs to streams. These contaminants 

accumulate on impervious surfaces in 

urban areas of the basins between storms 

and are transported to streams in storm 

runoff. For example, mean concentrations of total nitrogen and phosphorus in 

runoff to Little Cottonwood Creek were 

9.6 and 1.8 mg/L, respectively, during a 

storm in April 2000 (Gerner and Waddell, 2003) (fig. 18). The storm runoff 

resulted in elevated concentrations in the 

creek during the storm (6.5 and 

1.2 mg/L of total nitrogen and phosphorus, respectively). The phosphorus concentrations greatly exceeded the USEPA 

recommended goal of 0.1 mg/L to prevent nuisance plant growth in streams. 

Storm runoff also carried pesticides, particularly the insecticide carbaryl and the herbicide prometon (which 

is easily dissolved in and transported by 

water). Carbaryl can be toxic to fish and 

aquatic invertebrate animals. In fact, the 

concentration of carbaryl, in storm runoff and in stream samples collected during rainstorms, exceeded the Canadian 

water-quality guideline for the protection of aquatic life (0.20 μg/L)(Canadian 

Council of Ministers of the Environment, 2002) (fig. 18). These events are 

intermittent; however, they are important 

to consider, particularly when they occur 

during critical life cycles of aquatic 

organisms.

The concentration of dissolved solids in streams generally is lower during 

storms because of dilution. Exceptions 

occur in some study-unit urban streams, 

such as Little Cottonwood Creek, during 

and immediately following snowstorms 

The median concentration of nitrate in shallow ground 

water underlying residential and commercial land in Salt Lake 

Valley (6.8 mg/L) was almost 5 times the national NAWQA 

median for urban ground-water studies (1.4 mg/L) and was 

the highest found in 34 NAWQA studies across the Nation. 

Nitrate concentrations in water from 3 of the 30 monitoring 

wells in Salt Lake Valley exceeded the USEPA drinking-water 

standard of 10 mg/L, which was established because concentrations above this level are known to cause a blood disorder in infants, commonly called blue-baby syndrome. Water 

from the shallow aquifer underlying Salt Lake Valley is not 

currently used for drinking, but a longer term concern is the 

potential for contaminated water that might enter the shallow 

aquifer to move downward to the underlying basin-fill aquifer 

that is used for public supply. Such downward movement 

may already be evident, as water from 12 of 31 public-supply 

wells contained concentrations of nitrate greater than 2 mg/L 

(the naturally occurring or “background” concentration). The 

median concentration was 1.3 mg/L. No value exceeded the 

drinking-water standard, and public suppliers regularly monitor the source water for nitrate.

Although nitrate does occur naturally in ground water, 

elevated concentrations in urban areas, such as in Salt Lake 

Valley, are likely caused by human activities related to, for 

example, fertilizers applied to lawns and gardens and leaking 

or improperly functioning septic systems and sewer pipes.

Median concentration of nitrate—In milligrams per liter. Each circle represents

an urban ground-water study

Highest (greater than 5)

Medium (0.4 to 5)

Lowest (less than 0.4)

Background concentration

Bold outline indicates median values greater than background concentration

(2 milligrams per liter)

Average annual total nitrogen input—In pounds per acre, by county, for 1995–98.

Inputs are from fertilizer, manure, and the atmosphere

Greater than 25

6 to 25

Less than 6

No data available

Urban areas

USmap02

EXPLANATION

Great Salt

Lake Basins

Median nitrate concentration in Salt Lake Valley shallow 

ground water is the highest for urban areas in the Nation 
12 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

because of increased inputs of sodium 

and chloride from deicing of roadways. 

For example, the chloride concentration 

in Little Cottonwood Creek during a 

1999 winter storm exceeded 2,900 mg/L 

(fig. 19); conversely, chloride concentrations in Red Butte Creek (an adjacent, 

undeveloped basin) remained about 

12 mg/L. Chloride concentrations in 

Little Cottonwood Creek exceeded the 

acute USEPA aquatic-life criterion for 

chloride (860 mg/L) (U.S. Environmental Protection Agency, 2002a) in 10 

percent of the samples, and the chronic 

criterion (230 mg/L) in 61 percent of 

the samples collected during December 

1999 through March 2000. 

Elevated concentrations of chloride 

can cause acute and chronic toxicity in 

aquatic organisms. Even moderate concentrations can affect community structure, diversity, 

and productivity (Environment Canada and Health 

Canada, 2001). The effects 

of chloride are particularly 

evident in Little Cottonwood Creek, where several 

types of algae tolerant to 

saline conditions, such as 

Nitzschia inconspicua and 

Navicula veneta, are most 

dominant.

Urban storm runoff 

may be a source of certain 

VOCs in surface water and 

ground water. Many of 

the same VOCs, such as 

tetrachloroethene (PCE) 

and trichloroethene (TCE), 

commonly were detected 

in both storm runoff and 

shallow ground water from 

urban areas across the 

United States (Lopes and 

Bender, 1998). In urban 

Salt Lake Valley, elevated 

concentrations of gasolinerelated compounds (1,2,4-

trimethylbenzene, xylene, 

and toluene), chloroform, 

and TCE were measured 

during storm events in 

water sampled from Little 

Cottonwood Creek. Chloroform and TCE also were 

detected in shallow ground water. 

Water temperature is another 

stream characteristic that is altered by 

storm runoff. During storms, water 

temperature in urban streams sometimes 

increased by 3o to 5o Celsius (oC). Urban 

streams draining a higher percentage 

of high-density residential/commercial 

land had larger and longer alterations in 

temperature during storms than streams 

draining other types of land. Rapid or 

prolonged temperature changes can alter 

streamwater chemical characteristics 

considerably and can adversely affect 

aquatic organisms that are intolerant to 

these changes. For example, increased 

stream temperature can reduce the 

amount of oxygen available for aquatic 

organisms while at the same time 

increasing their metabolic rate and oxygen needs.

Elevated levels of pesticides 

are most common in urban 

streams

Water samples collected from 

streams were analyzed for 107 pesticides, of which 49 were detected 

(Gerner, 2003). At least one pesticide 

was detected in 23 of the 24 streams 

sampled. Pesticides (herbicides and 

insecticides) are applied in many agricultural and nonagricultural settings 

in the Study Unit to control unwanted 

vegetation and destructive insects. On 

average, samples from streams in basins 

with predominantly urban or mixed land 

cover contained more pesticides than 

samples from streams in agricultural and 

undeveloped basins (fig. 20). The number of pesticides detected in individual 

samples in each stream ranged from 

none in many samples collected at forest 

and rangeland sites to 16 in a sample 

from the Jordan River, a stream whose 

water quality is influenced by mixed, but 

predominantly urban, land uses.

The types of pesticides detected 

also differed by land use. Specifically, 

insecticides—most commonly carbaryl, diazinon, and malathion—occurred 

more frequently in urban streams than in 

agricultural streams. For example, diazinon was detected in about 90 percent 

of 42 samples from the urbanized Little 

Cottonwood Creek but in only about 

4 percent of 26 samples from the agricultural Cub River.

0

500

1,000

2,000

1,500

USEPA aquatic-life guidelines

(acute 860 mg/L,

chronic 230 mg/L)

December January February March

1999 2000

3,000

2,500

0

10

20

SNOWFALL, IN INCHES

Chloride

Snowfall

ESTIMATED CHLORIDE CONCENTRATION,

IN MILLIGRAMS PER LITER

Figure 19. Chloride concentration in 

Little Cottonwood Creek often exceeded 

aquatic-life guidelines.

0

2

4

6

8

10

NITROGEN

TOTAL

PHOSPHORUS

TOTAL

0

1.0

2.0

CARBARYL PROMETON

Nonstorm sample

Urban runoff

(calculated)

Storm sample

CONCENTRATION, IN MILLIGRAMS PER LITER

CONCENTRATION, IN MICROGRAMS PER LITER 1.5

0.5

Canadian

water-quality

aquatic-life

guideline

(0.20 microgram

per liter)

Figure 18. Nutrients and pesticides are transported to 

Little Cottonwood Creek in urban runoff, substantially 

increasing the concentration of these contaminants during 

storms.
Major Findings 13

The median total concentration of 

pesticides measured in water samples 

from streams representative of undeveloped and agricultural land uses 

(0.004 and 0.041 μg/L (microgram per 

liter), respectively) was lower than 

that measured in samples from streams 

principally affected by urban land and 

mixed land uses (0.095 and 0.077 μg/L, 

respectively) (fig. 21). The concentration 

of pesticides in surface-water samples 

from the Study Unit was generally low. 

Ninety-seven percent of the samples had 

a total pesticide concentration less than 

1 μg/L. The maximum concentration of 

pesticides (6.54 μg/L) was measured in a 

aquatic community. The implications 

for aquatic organisms of those pesticides 

detected that do not have aquatic-life 

guidelines are unknown. None of the 

pesticides detected in streams exceeded 

human-health standards for drinking 

water; however, the USEPA has established standards for only 23 of the 49 

pesticides detected.

VOCs are common in urban 

streams

Water samples from two urban 

streams, Little Cottonwood Creek and 

the Jordan River, were analyzed for 86 

volatile organic compounds (VOCs), 

33 of which were detected. Some likely 

pathways for VOCs to enter urban 

streams include (1) direct discharge into 

the stream from accidental spills and 

industrial or wastewater discharge; (2) 

industrial and vehicle emissions, scavenged from air by precipitation, deposited directly into the stream, or transported in runoff; and (3) contaminated 

ground-water inflow. 

The number of VOCs detected 

per sample ranged from 3 to 20. Fuelrelated BTEX (benzene, toluene, ethyl 

benzene, and xylenes) compounds were 

the most frequently detected group of 

compounds in Little Cottonwood Creek. 

sample collected from an urban site near 

the mouth of Little Cottonwood Creek 

during a rainstorm (see “Urban storm 

runoff affects stream chemistry and temperature”).

Eighteen of 49 pesticides detected 

in stream samples have guidelines for 

the protection of aquatic communities. 

Concentrations of carbaryl, diazinon, 

and malathion exceeded those guidelines (in 5, 19, and 4 samples, respectively), indicating the potential for 

impairment of some portions of the TOTAL PESTICIDE CONCENTRATION, IN MICROGRAMS PER LITER

DOMINANT STREAM BASIN LAND COVER

1

0.01

0.001

0.1

10

Median

Undeveloped Agricultural Urban Mixed

Figure 21. The highest concentrations of 

pesticides were measured in samples from 

urban streams.

Figure 20. More pesticides were 

detected in streams affected by urban land 

use than in agricultural or undeveloped 

(forest/rangeland) streams. AVERAGE NUMBER OF PESTICIDES PER SAMPLE 1

2

3

4

5

6

Undeveloped Agricultural Urban Mixed

7

DOMINANT STREAM BASIN LAND COVER

Some pesticides frequently detected nationally in 

surface-water samples also are found in the 

Great Salt Lake Basins Study Unit

The types of pesticides in streams 

are closely linked to pesticide use. 

Such relations help to explain why 

some pesticides are found in streams in 

the Great Salt Lake Basins and across 

the Nation, while others are not. For 

example, atrazine, which was detected 

in 100 percent of the samples collected 

from the Jordan River, which drains 

land with mixed cover types, also was 

commonly detected (in 88 percent of 

samples) in 47 rivers across the Nation 

that drain land with mixed cover types. 

Similarly, the insecticide diazinon and 

the herbicide prometon, which were 

detected in about 90 percent of the 

samples collected from the urbanized 

Little Cottonwood Creek near Salt Lake 

City, were commonly detected in 32 

other urban streams across the Nation 

(65 percent for diazinon and 85 percent 

for prometon).

The frequency of detection of 

several pesticides in the Great Salt 

Lake Basins differed from that of other 

streams across the Nation. For example, 

carbaryl, which was detected in 38 percent of samples collected from the agricultural Cub River, was detected in only 

9 percent of samples collected from 78 

agricultural streams across the Nation. 

Simazine was frequently detected 

nationally (61 percent of 154 samples), 

but was detected in only 17 percent of 

the samples collected from streams in 

the Great Salt Lake Basins. Metolachlor 

was detected infrequently in streams in 

the Great Salt Lake Basins (only 5 percent of samples) but was detected in 73 

percent of 157 samples collected from 

other streams across the Nation.
14 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

The number and frequency of 

pesticides and VOCs detected in water 

from streams was greater than those 

detected in water from wells (fig. 22). 

Ground water has a lower incidence of 

contamination than streams because 

water infiltrating the land surface moves 

slowly through soil and rock formations. This contact, along with the slow 

rate of flow, allows greater opportunity 

for sorption, retardation, degradation, 

and dispersion of contaminants that 

can reduce the concentration or remove 

the compounds from ground water. In 

addition, because of the slow rate of 

flow, many compounds in recharged 

water have not yet reached the sampled 

wells, but may in the future.

Pesticides that are generally 

chemically stable and mobile in ground 

water, including prometon, atrazine, 

deethylatrazine, and simazine, commonly were detected in streams and 

wells. Chemically less stable pesticides, including insecticides that are 

generally applied in lesser quantities, 

commonly were detected in water 

from streams but not from wells. 

VOCs generally had a greater 

frequency of detection in streams, 

with the exception of the chlorinated drinking water byproducts, 

chloroform and bromodichloromethane, which were detected 

at similar frequencies in surface 

water and ground water. 

Figure 22. The frequency of 

detection and number of pesticides and VOCs in water samples were greater for streams 

than for wells. Pesticides and 

VOCs that occurred in less than 

5 percent of both streams and 

well samples are not shown. 

Pesticides and VOCs were detected 

more frequently in water from 

streams than from wells

PESTICIDE COMPOUND

Prometon

Atrazine

Deethylatrazine

Tebuthiuron

Pendimethalin

DCPA

Trifluralin

Simazine

Metolachlor

EPTC

Benfluralin

Diazinon

Carbaryl

Malathion

Chlorpyrifos

p-p’ DDE

50 40 30 20 10 0 10 20 30 40 50 60 70 80 90

Ground water Surface water

Trihalomethanes

BTEX and

fuel-related compounds

Solvents

Chloroform

Bromodichloromethane

Bromoform

Dibromochloromethane

Toluene

Benzene

1,2,4-Trimethylbenzene

p-Isopropyltoluene

o-Ethyl toluene

m- and p-Xylene

o-Xylene

Ethylbenzene

Styrene

Methyl tert-butyl ether

1,2,3-Trimethylbenzene

n-Butylbenzene

Isopropylbenzene

Tetrachloroethene

Acetone

cis-1,2-Dichloroethylene

Trichloroethene

Carbon disulfide

Methylene chloride

1,3,5-Trimethylbenzene

Methylchloride

n-Propyl-benzene

Carbon tetrachloride

Isodurene

Chlorobenzene

1,1,1-Trichloroethane

1,2,3,4-Tetramethylbenzene

Dichloromethane

Methylisobutylketone

1,4 Dichlorobenzene

Methylethylketone

Ethyl-ether

o-Dichlorobenzene

VOLATILE ORGANIC COMPOUND

Ground water Surface water

Other VOCs

Herbicides

Insecticides

DETECTION FREQUENCY, IN PERCENTAGE OF SITES

VOCs were commonly detected in 

shallow ground water underlying residential 

and commercial areas in Salt Lake Valley. 

Seventeen of 30 wells (almost 60 percent) 

contained water with at least 1 VOC measured at concentrations equal to or greater 

than a common national assessment level of 

0.2 μg/L. The percentage of VOC detections in Salt Lake Valley ranks 9th out of 

33 urban areas assessed by the NAWQA 

Program. The types of VOCs detected were 

similar. For example, chloroform, a disinfection byproduct and solvent, was the most 

frequently detected VOC nationally and in 

shallow ground water underlying Salt Lake 

Valley. Tetrachloroethene (PCE), a solvent 

used for degreasing and dry cleaning, also 

was common nationally (found at concentrations greater than 0.2 μg/L in about 

10 percent of wells), and was even more 

common in Salt Lake Valley (approximately 

25 percent of the wells). The similarity 

does not extend to methyl tert-butyl ether 

(MTBE), a gasoline additive used to reduce 

air pollution. MTBE was the second most 

common VOC nationally, but was not 

detected above 0.2 μg/L in any well in Salt 

Lake Valley. MTBE is not commonly used 

in the area.

VOCs are more common in shallow ground water 

underlying Salt Lake Valley than in most other 

urban areas sampled across the Nation

Urban land-use

studies

Across the nation

Salt Lake Valley

Top five most frequently detected VOCs

in urban land-use areas

(assessment level of 0.2 μg/L)

Chloroform

Methyl tert-butyl

ether

Tetrachloroethene

Trichloroethene

1,1,1-

Trichloroethane

DETECTION FREQUENCY,

IN PERCENTAGE OF SITES

0 10 30 20 40 50 60

Disinfection

byproduct

Fuel

oxygenate

Solvent

Solvent

Solvent
Major Findings 15

Trihalomethanes (THMs, see box below) 

were the most frequently detected group 

of compounds in the Jordan River. 

Treated wastewater was a large component of streamflow at the Jordan River 

site, which most likely explains why 

THMs were detected more frequently 

in water samples from the Jordan River 

than in samples from Little Cottonwood 

Creek. Concentrations of most VOCs in 

water samples were less than 

1 μg/L. Eleven percent of the VOC 

detections were greater than 1 μg/L, 

with a maximum concentration of 

20 μg/L (acetone).

Pesticides and VOCs are 

detected in basin-fill aquifers 

underlying all types of land use

Pesticides in water from the basinfill aquifers throughout the Study Unit 

were detected more often and at higher 

concentrations in samples collected 

from wells in agricultural areas than in 

areas dominated by rangeland or urban 

land uses (fig. 23). Detections of pesticides in water from the aquifers consisted predominantly of the herbicides 

atrazine and its degradation product 

deethylatrazine (DEA), prometon, and 

simazine. Atrazine and simazine are 

selective herbicides commonly used on 

crops and orchards in agricultural areas 

and to control vegetation in industrial 

areas. Prometon is used primarily along 

road rights-of-way and urban corridors. 

Atrazine and DEA were detected in 23 

and 31 percent, respectively, of samples 

collected from wells in the basin-fill 

aquifers. Many of the samples with 

detections were collected from wells 

in primary recharge areas that historically have been undeveloped or used for 

agricultural purposes but have become 

increasingly urbanized. 

VOCs were detected in 63 percent 

of the ground-water samples collected 

from the basin-fill aquifers throughout 

the Study Unit. Wells surrounded by 

predominantly urban and agricultural 

land had a slightly higher frequency of 

detection, 66 and 63 percent respectively, than wells located in rangeland 

(54 percent) areas (fig. 23). The two 

most frequently detected VOCs in 

the basin-fill aquifers were the THMs 

chloroform and bromodichloromethane, 

which were detected in 37 and 19 percent of samples, respectively.

The detected pesticide and VOC 

concentrations were well within USEPA 

drinking-water standards (U.S. Environmental Protection Agency, 2002b) and 

are not a known health concern; however, their widespread occurrence in the 

aquifers indicates the presence of water 

recharged recently enough to be affected 

by human activities. 

VOCs and pesticides commonly 

are detected in shallow ground 

water and in the basin-fill aquifer used for public supply in 

Salt Lake Valley

At least 1 VOC was detected in 

water from 27 of 30 monitoring wells 

completed in the shallow aquifer 

beneath recently developed residential 

and commercial areas of Salt Lake Valley (Thiros, 2003b; see inset on page 

14). The most frequently detected VOCs 

were THMs (chloroform and bromodichloromethane) and those used as solvents (PCE and 1,1,1-trichloroethane). 

The widespread occurrence of THMs at 

low concentrations in shallow ground 

water is likely a result of chlorinated 

public-supply water used to irrigate 

lawns and gardens in residential areas of 

Salt Lake Valley that has recharged the 

aquifer. Water disinfected for public supply also can enter the ground-water system through leaking water lines, sewer 

lines, and swimming pools. PCE was 

detected in water from 16 monitoring 

wells completed in the shallow aquifer 

at concentrations up to 7.8 μg/L, exceeding the USEPA drinking-water standard 

of 5 μg/L. PCE is used primarily as a 

dry-cleaning agent and a solvent.

The herbicides atrazine and its 

degradation product DEA were the 

most frequently detected pesticides in 

water from the shallow aquifer in Salt 

Lake Valley and were found in 77 and 

70 percent of the samples, respectively. 

Atrazine concentrations in water from 

the monitoring wells ranged from less 

than 0.001 to 1.58 μg/L (fig. 24), less 

than the USEPA drinking-water standard of 3 μg/L. All but one of the water 

samples from the western side of the 

valley contained detectable concentrations of atrazine. The high detection 

frequency of atrazine in shallow ground 

water underlying primarily residential 

areas on the western side of the valley 

may be the result of past application in 

agricultural or industrial areas that have 

been converted to residential uses. Also, 

atrazine applied in nonurban areas may 

have been transported to urban areas in 

the Study Unit by ground water. The 

Agricultural Rangeland Urban

FREQUENCY OF SAMPLES WITH AT LEAST

ONE COMPOUND DETECTED, IN PERCENT

Pesticides

VOCs

DOMINANT LAND-USE SURROUNDING

SAMPLED WELLS

80

60

20

0

30

40

70

10

50

Figure 23. Pesticides were detected 

more frequently in ground-water samples 

from the basin-fill aquifers in agricultural 

areas than in rangeland and urban areas, 

and VOCs were detected at a higher 

frequency in agricultural and urban areas 

than in rangeland areas. 

Chloroform, bromodichloromethane, dibromochloromethane, and bromoform form a group 

of compounds known as trihalomethanes, or 

THMs. THMs are formed when chlorine, used 

to disinfect drinking water, reacts with naturally 

occurring organic materials. THMs are carcinogenic and have a USEPA cumulative drinkingwater standard of 80 μg/L. 
16 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

four wells with the highest concentrations of atrazine and its degradation 

products also had minimal concentrations of chloroform, which likely comes 

from watering lawns with chlorinated 

water. This correlation suggests that the 

recharge area for these wells includes 

more agricultural or nonirrigated industrial and vacant land than residential 

land.

The compounds detected in shallow ground water and used at the land 

surface have the potential to move to 

the deeper basin-fill aquifer in Salt Lake 

Valley, which is used for public supply. 

VOCs and (or) pesticides were detected, 

mostly at low concentrations, in water 

from 23 of 31 public-supply wells sampled in the valley. Although the concentration of these compounds measured in 

ground water used for public supply is 

not a known health concern according to 

current standards, their occurrence in the 

deeper ground water presents the possibility that water with higher concentrations may enter the aquifer in the future.

Elevated nitrate concentrations and the occurrence of pesticides, VOCs, and other manmade 

compounds in the deeper basin-fill 

aquifer underlying Salt Lake Valley 

indicate relatively recent (within the 

past 50 years) recharge of water to 

the ground-water system (Thiros and 

Manning, 2004). The apparent age 

for water sampled from public-supply wells in the valley ranges from 3 

to more than 50 years.1 Ground water 

is generally older with distance from 

the mountain front, the oldest water 

being in the discharge area toward 

the center of the valley (fig. 25). 

Concentrations of manmade 

compounds generally decreased 

with the age of water and were not 

detected in water older than 50 years 

from many of the public-supply 

wells. For example, summed concentration of VOCs and pesticides generally was in the range of 0.1 to 10 μg/L 

in water younger than 20 years of age 

and was less than 0.01 μg/L in water 

about 50 years or more in age (fig. 

26). Similarly, nitrate concentrations 

were lower in the older ground water. 

Manmade compounds were detected or 

chlorofluorocarbon (CFC) contamination occurred in water from five wells 

with shallow, open intervals in groundwater discharge areas within Salt Lake 

Valley. This indicates that the aquifer in 

the discharge area can receive modern 

water recharged in the valley despite the 

natural upward gradient.

Most ground water used for public supply in 

Salt Lake Valley was recharged in the past 

50 years and contains manmade compounds

100

10

1

0.1

0.01

0.001

No VOC or

pesticide detected

CONCENTRATION OF MANMADE COMPOUNDS, IN MICROGRAMS PER LITER

0 10 20 30 40 >50

APPARENT TRITIUM/HELIUM-3 AGE, IN YEARS

NITRATE CONCENTRATION,

IN MILLIGRAMS PER LITER 2

3

4

5

6

7

1

0

Discharge area

Recharge area

Water from 6 wells did not contain detectable

concentrations of VOCs or pesticides and

had apparent ages of greater than 50 years

Figure 26. The concentration of manmade compounds and nitrate in water 

from 31 public-supply wells in Salt Lake 

Valley generally increased as the apparent tritium/helium-3 age of the water 

decreased.

Figure 25. Apparent ages for water 

sampled from public-supply wells in the 

basin-fill aquifer range from 3 to more 

than 50 years.

Apparent 3H/3He age, in years

Less than 10 10 to 20 20 to 30 30 to 40

40 to 50 Greater than 50

Approximate boundary of basin-fill deposits in Salt

Lake Valley

Public-supply well—Number is apparent age in years

EXPLANATION

40°

30'

40° 45'

Jordan River

0 3 6 KILOMETERS

0 3 6 MILES

112°07'30" 111°48'

21

18

27

18

>50

>50

36

31

18

Great Salt Lake OQUIRRH MOUNTAINS

WASATCH MOUNTAINS

Salt

Lake

Valley

>50

1Ground-water ages determined from environmental tracers such as tritium, helium-3, and CFCs are 

interpreted from measured concentrations and can be affected by mixing between waters with different 

ages, dispersion, and other factors and, therefore, are usually qualified as “apparent ages.” 

N

0 2 3 KILOMETERS

0 2 3 MILES

1

1

Discharge area

Primary recharge area

Secondary recharge area

Recent residential/commercial land use

Approximate limit of basin-fill material

Atrazine concentration, in micrograms per liter

Less than 0.001

0.001 to 0.020

0.020 to 0.100

0.100 to 1.00

1.00 to 1.58

EXPLANATION Jordan River

WASATCH MOUNTAINS

Salt

Lake

Valley

Figure 24. Atrazine was detected more 

frequently and at higher concentrations in 

water sampled from monitoring wells on 

the west side of Salt Lake Valley, Utah.
Major Findings 17

for other cities in the United States and 

associated it with increased vehicular 

traffic in their watersheds. PAH concentrations in sediment will probably 

continue to increase as urbanization and 

associated vehicular traffic and fossil 

fuel use increase. 

Lead concentrations have 

decreased in Farmington Bay 

sediments since the 1980s

Unlike other contaminants, lead has 

shown a recent decline in concentration 

in Farmington Bay sediments (see inset, 

page 18). Recent sediments deposited 

during 1996–98 indicate a 41- to 62-

percent reduction in lead concentration 

since the peak in the mid-1980s. The 

concentration of lead began to increase 

after about 1842, made the most marked 

increase between about 1916 and 1950, 

and peaked in the 1980s (fig. 29). The 

early increases have been attributed to 

atmospheric deposition from historical 

mining activities associated with smelters in Salt Lake Valley. 

Mining and smelter activities had 

already declined considerably in Salt 

Lake Valley by the mid-1980s, when the 

concentration of lead started to decrease 

Surface-water 

contaminants and 

aquatic communities 

change as watersheds 

become urbanized

PAH levels are elevated in 

streambed sediment in urban 

basins and in Farmington Bay 

Many contaminants, like trace 

elements, organochlorine compounds, 

and polycyclic aromatic hydrocarbons 

(PAHs), generally sorb to soil and sediment, are chemically stable and persistent, and tend to accumulate in aquatic 

organisms. Concentrations of PAHs in 

streambed sediment increase from the 

most upstream to the most downstream 

site of major urban areas in the Weber 

and Utah Lake-Jordan River Basins 

(fig. 27). PAHs are formed by the incomplete combustion of hydrocarbons—

coal, oil, gasoline, and wood—resulting from many urban sources including 

industrial and powerplant emissions, 

home heating, refuse and open burning, 

car and truck exhaust, tires, and asphalt 

roads and roofs (Edwards, 1983). 

Samples from a Jordan River 

site, located downstream from the Salt 

Lake City metropolitan area (fig. 27), 

had the highest concentration of total 

PAHs in streambed sediments in the 

Study Unit (1,630 μg/kg [micrograms 

per kilogram]) (Waddell and Giddings, 

2003). Contaminants deposited on land 

can wash into streams and seep into 

ground water. Soil and debris (and any 

attached contaminants) carried by runoff 

or atmospheric deposition can settle 

to the bottom of reservoirs, lakes, and 

other impoundments in successive layers 

over time. USGS analysis of sediment 

cores (vertical tubes of mud) from lake 

bottoms across the country document 

changes in contamination as watersheds 

become increasingly more urbanized. 

Concentrations of total PAHs in 

sediment from Farmington Bay of Great 

Salt Lake, which receives water from the 

Jordan River, increased from less than 

100 μg/kg in sediments deposited before 

1940 to more than 2,000 μg/kg after 

the mid-1980s (Naftz and others, 2000) 

(fig. 28). During this time, the population in Salt Lake County also increased, 

causing increased vehicular traffic and 

human-induced combustion products. 

Van Metre and others (2000) documented the pattern of increased PAHs 

Figure 27. PAHs increase in sediments 

from upstream to downstream in each 

basin. 

0 500 1,000 1,500 2,000

Downstream

TOTAL PAHs IN BED SEDIMENT, IN

MICROGRAMS PER KILOGRAM

Tributary (undeveloped)

Bear River Basin

Utah Lake-Jordan River Basin

Weber River Basin

Tributary (urban)

Utah Lake (headwaters of

Jordan River)

Bear Lake Tributary (agriculture)

Provo River

Upstream

Bear River

Tributary (agriculture)

Tributary (urban)

Jordan River

Jordan River

Bear River

Weber River

Weber River

Bear River

Farmington Bay Great Salt Lake

Jordan River

Jordan River

Figure 28. PAHs have increased as the 

population of Salt Lake County has grown, 

as evidenced by an increase of these 

compounds with time in the sediment of 

Farmington Bay. 

1,000

1930

1940

1950

1960

1970

1980

1990

2000

POPULATION OF

SALT LAKE COUNTY,

IN THOUSANDS

100 400 700 0 1,000 2,000 3,000

10

8

6

4

2

0

SEDIMENT DEPTH, IN INCHES

TOTAL PAHs, IN

MICROGRAMS

PER KILOGRAM

1995

1980

1965

1950

1937

2000

1930

Figure 29. Lead concentration in sediment core from Farmington Bay indicates 

increasing inputs after about 1842, 

coinciding with the mining and smelter 

activities in the region. 

0

12

10

8

6

4

2

0

1738

1776

1810

1842

1878

1916

1950

1974

1986

1996

SEDIMENT DEPTH, IN INCHES

100 200

LEAD CONCENTRATION,

IN MICROGRAMS

PER GRAM

PAHs represent the largest class of suspected carcinogens (Björseth and Ramdahl, 

1985) and can present a threat to aquatic life 

(Long and Morgan, 1991). 
18 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

in Farmington Bay sediments. Thus, 

recent declines in lead concentration in 

sediments of Farmington Bay probably are mostly due to reduced lead in 

automobile emissions. Recent declines 

in lead concentration in sediment have 

been noted elsewhere and usually are 

attributed to reduction in lead emissions following passage of the Clean Air 

Act of 1970 (Callender and Van Metre, 

1997).

DDT, PCBs, and other organochlorine compounds occur 

more commonly in fish than in 

sediment in area streams

Twenty-seven organochlorine 

compounds were analyzed in streambed 

sediment and fish tissues at 15 sites. 

Twelve compounds were detected in fish 

tissue, whereas only 6 of the compounds 

were detected in sediment. All of the 

compounds detected in the sediment 

were also detected in tissue at each site 

(fig. 30). These data illustrate the tendency for these compounds to accumulate in fatty tissue. 

concentrations of organic compounds in 

fish tissue and sediment from the Study 

Unit were lower than those in other 

areas studied as part of the NAWQA 

Program.

The concentrations of DDT compounds in sediment were between the 

threshold effect level (TEL)1 and probable effect level (PEL) for aquatic life at 

three sites. Concentrations between the 

TEL and PEL indicate possible 

Two commonly detected compounds were PCBs and DDT, although 

the use of these compounds was discontinued in the United States in the 1970s. 

In 1998, PCBs were detected in wholefish samples from 8 of 15 sites, and 

DDT breakdown products were detected 

at 13 of 15 sites. PCBs were detected 

in bed-sediment samples at only 2 of 

15 sites, and DDT compounds were 

detected at 4 of 15 sites. In general, 

1

Currently there are no U.S. standards for assessing the potential for adverse biological effects due to contaminated freshwater sediment. The Canadian 

Council of Ministers of the Environment (CCME) modified an approach by Long and Morgan (1991) to develop guidelines for marine and freshwater sediment. 

The CCME modified approach uses two assessment levels: (1) the threshold effect level (TEL), representing the concentration below which adverse effects are 

expected to occur rarely, and (2) the probable effect level (PEL), representing the concentration above which adverse effects are expected to occur frequently 

(Ecosystem Conservation Directorate Evaluation and Interpretation Branch, 1995). 

Figure 30. Organic compounds were 

detected more frequently in fish tissue 

than in sediment.

0 100 200 300 400

MICROGRAMS PER KILOGRAM

Bear River Basin

Jordan River Basin

Weber River Basin

300 200 100

Sediment

(dry weight)

Fish

(wet weight)

Downstream Upstream

Total DDT

Total Chlordane

Total PCB

Trends in DDT, PCBs, and chlordane in 

Farmington Bay sediment are different 

from those at other sites nationally

As a part of the NAWQA Program, trends in polychlorinated 

biphenyls (PCBs) and organochlorine 

compounds were tracked over the 

last several decades to the mid-to-late 

1990s in sediment cores from 10 lakes 

and reservoirs in 6 U.S. metropolitan 

areas (Van Metre and others, 2000). 

Nationally, total DDT concentration generally followed the historical use of DDT (an organochlorine insecticide) in the United States, 

which peaked from the 1950s to the 

mid-1970s and then declined substantially. DDT use was discontinued in 

the United States in 1972; however, in 

Farmington Bay, which receives inflow 

from the Jordan River after it flows 

through the metropolitan area of Salt 

Lake City, the concentration was still 

increasing in the mid-1990s. Similarly, 

total PCB concentrations increased 

substantially between 1950 and 1965, 

coinciding with peak production, but 

concentrations in Farmington Bay sediment have not declined as at other sites 

nationally. Chlordane concentrations 

in Farmington Bay sediment began 

increasing significantly after 1950 and 

were still increasing in 1995, even 

though chlordane was discontinued 

from general use in the 1970s. 

The reasons for the continued 

trend of increasing concentrations 

of DDT, PCBs, and chlordane in the 

sediment cores from Farmington Bay 

are not understood at this time and 

will require further investigation. The 

relatively low concentrations in the 

sediments of streams in the Study Unit 

suggest that the concentrations should 

decrease in the bay with times.

Total PCB

0

50

100

150

200

Chlordane

0

10

20

30

40

50

60

70

Total DDT

CONCENTRATION, IN MICROGRAMS PER KILOGRAM

1930 1940 1950 1960 1970 1980 1990 2000

0

5

10

15

20

Farmington Bay sediment cores
Major Findings 19

occasional adverse biological effects are 

expected. Adverse biological effects are 

generally defined as effects that are considered to produce a negative response 

in an organism, such as reduced reproductive success, reduction in growth, or 

death.

Increased urban land use has 

altered invertebrate and algal 

communities 

Researchers have shown that 

as urbanization increases in a watershed, streams typically show a decline 

in water quality and condition of the 

physical habitat, which in turn leads 

to a decline in the quality of biological communities in the streams. (For a 

review of literature on effects of urban 

land use, see Paul and Meyer, 2001.) 

Effects of urbanization on streams along 

the Wasatch Mountains were examined 

using a special “urban gradient design” 

(see inset). Differences in the physical, 

chemical, and biological characteristics 

of 30 sites along a gradient of urbanization were compared with the level of 

urban intensity in each watershed to see 

if urbanization was having a measurable 

effect on these characteristics. The area 

included in the urban-gradient assessment has strong natural gradients, and 

the hydrology and chemistry of the 

streams are affected to a large degree by 

the movement of water across watershed 

boundaries to meet human water-use 

needs.

The urban-gradient assessment 

showed that water quality of the streams 

declined with increasing levels of urban 

intensity. Specifically, increasing concentrations of nutrients (nitrogen and 

phosphorus), warmer water temperatures, a greater number of pesticides, 

and increasing specific conductance 

were associated with increasing urban 

intensity (fig. 32). Specific conductance 

is a measure of dissolved ions in the 

water, and increasing values most likely 

indicate increased runoff associated with 

increasing urban intensity. Urban runoff 

commonly contains contaminants that 

are harmful to biological communities. 

An increase in dissolved 

The Great Salt Lake Basins Study Unit was one of several NAWQA Study 

Units that participated in an urban land-use gradient study. This special study was 

designed to examine the effects of urbanization on streams by sampling physical, 

chemical, and biological characteristics of 30 sites along a gradient of low to high 

levels of urbanization (fig. 31) and to compare how urbanization affects streams in 

different parts of the country. An integrated index of “urban intensity” was used to 

define urban effects at each site (McMahon and Cuffney, 2000). Each watershed 

was ranked in urban intensity (ranging from 0 to 100) on the basis of 13 measures 

of urbanization, including measures of land cover (for example, percentage of land 

surface covered with vegetation), urban infrastructure (for example, the density 

of roads), and socio-economic characteristics (for example, the density and type 

of housing, population density). For reference, an urban index of 50 represents 

approximately 30 percent land cover that is urbanized and an average road density 

of approximately 17 kilometers of roads per square kilometer area. A low rating on 

the urban index means there is very little urban development in the watershed and 

the land is mostly forested. A high rating on the urban index represents a watershed with a mixture of higher density housing and(or) commercial space. Along the 

western front of the Wasatch Mountains, the intensity of urbanization tends also to 

follow the elevation gradient, with the most intensely urbanized areas at the valley 

bottom.

The characteristics of streams, be they physical, chemical, or biological, also 

change along the elevational gradient, regardless of differences in urbanization. 

Because the objective was to measure changes due to urbanization, the study sites 

were limited to only those on the benchlands of the Wasatch Mountains, and, as a 

result, the study did not sample the high intensity urban areas at the valley bottoms.

40°

41°

42°

112° 111°

Great

 Salt

 Lake

Weber

River

Provo

River

River

Jordan

Bear

River

Bountiful

Brigham City

Logan

Ogden River

Weber

Ogden

River

Provo

EXPLANATION

Urban area

Urban land-use

gradient site

Inset A

Inset B

Inset C

Inset A

Inset B

Inset C

River

Jordan

River

Provo

Little

Cotton wood Creek

Big

Cottonwood

Creek

Mill Creek

Parleys Creek

Creek Emigration

Creek

Baer Creek Holmes

Creek Kays

South Fork

Fork

North

Creek

Farmington

Hobble

Spanish

Creek

Fork

Provo

Ogden Evanston

Salt Lake City

Utah Lake

IDAHO

UTAH Bear

Lake

Bear

River

WYOMING

0 20 40 60 KILOMETERS

0 20 40 60 MILES

Figure 31. Thirty sites were sampled for fish, macroinvertebrates, algae, water 

chemistry, and physical habitat along a gradient of urban intensity.

An Urban Gradient Study
20 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

nutrient concentrations and in the number of pesticides detected likely reflects 

the use of these compounds on lawns, 

parkways, roadways, and other areas of 

the urban landscape. High concentrations of nutrients and pesticides can be 

toxic to many stream organisms, and the 

presence of these chemicals in stream 

water can limit the numbers and kinds 

of organisms found in urban streams. In 

addition, water temperature can increase 

in the more highly urbanized areas as 

the amount of impervious surface area 

increases. For example, during storms, 

rainwater falling on hot pavement heats 

up and then runs into streams, increasing their temperature. Also, the temperature of the land surface in urban 

areas is often several degrees warmer 

than in the surrounding countryside. As 

the temperature of the ground surface 

in urban areas increases, the temperature of streams flowing through these 

areas may also increase. Many biological organisms have a limited temperature range in which they survive. An 

increase in stream temperature favors 

those organisms able to tolerate higher 

temperatures, thus altering the biological 

community. 

The quality of physical habitat, 

while substantially different among 

sites, did not show a strong correlation 

with the level of urbanization in the 

watershed. With the exception of 

substrate particle size, the differences 

in physical habitat among sites 

appeared most strongly related to 

natural gradients, such as basin size and 

altitude. The size of substrate (bottom 

material) in streams decreased as the 

intensity of urbanization increased. 

Small particles, such as sand and silt, 

were more common at more urbanized 

sites, where they may have been washed 

into streams from unvegetated areas, 

such as construction sites. In addition, 

dirt and silt accumulate on impervious 

areas (blacktop, rooftops, sidewalks) and 

can easily be washed into streams during 

rainstorms. When large amounts of these 

fine particles enter a stream channel 

they can clog the spaces between 

rocks on the stream bottom and reduce 

the availability of the stable habitat 

preferred by bottom-dwelling organisms. 

Algae and invertebrates living on 

the bottom of a stream channel are good 

indicators of changes in water quality 

and habitat conditions. As physical 

and chemical conditions change with 

urbanization, the number and type of 

organisms in a stream also changes. For 

example, as the intensity of urbanization 

increased, the relative abundance 

(percentage of all individuals collected) 

of algae that are tolerant to organic 

pollution, salinity, and silt increased, 

while the relative abundance of algae 

sensitive to pollution (intolerant algae) 

decreased (fig. 33). The increase in the 

abundance of algae tolerant of organic 

pollution corresponded to an increase in 

water-column nutrient concentrations. 

Likewise, the increase in silt-tolerant 

algae corresponded to a decrease in 

substrate particle size in the stream 

channel. 

Similarly, as the intensity of urbanization increased, the number of kinds 

of invertebrates (richness) sensitive to 

pollution decreased and the number of 

kinds of invertebrates tolerant of pollution increased (fig. 34). Generally, 

invertebrate organisms considered intolerant, such as mayflies and stoneflies, 

prefer lower water temperatures, require 

more stable substrate and flow regimes, 

and require good water quality. In contrast, the presence of tolerant invertebrates, such as midges and worms, 

generally increases under conditions of 

degraded habitat or poor water quality.

Although not measured directly in 

this study, the amount of water diversion 

and exchange in these streams likely 

is responsible, in part, for these alterations in biological communities. As 

discussed in the section “Water development affects quantity and quality of 

water resources,” the quality of water 

is affected by diversions. For example, 

stream temperature was substantially 

lower in urban streams with continuous 

0

20

40

60

80

PERCENTAGE OF RELATIVE ABUNDANCE

Algae tolerant of organic pollution

Algae tolerant of salinity

Intolerant algae

URBAN INDEX

0–25 26–50 51–75 76–100

Figure 33. As the level of urbanization 

increases, the percentage of algae tolerant 

of salinity (red) and organic pollution (green) 

increases, while the percentage of algae 

sensitive to pollution (blue) decreases.

Figure 34. As urban intensity in the 

watershed increases, the number of 

invertebrate taxa sensitive to pollution 

(blue) decreases while the number of 

invertebrate taxa tolerant to pollution (red) 

increases.

URBAN INDEX

PERCENT RICHNESS 0

10

20

30

40

50

0–25 26–50 51–75 76–100

Tolerant invertebrates

Sensitive invertebrates

NUMBER OF

PESTICIDES

DETECTED

0

2

4

6

8

10

12

14

SPECIFIC

CONDUCTANCE

0

200

400

600

800

1,000

1,200

0 20 40 60 80 100

URBAN INDEX

Figure 32. In samples collected in July, 

the number of pesticides detected and the 

specific conductance, in microsiemens 

per centimeter, of the water generally 

increased with increasing urban index 

values. 
Major Findings 21

flow from their mountainous watersheds 

(for example, Mill Creek, Provo River) 

than those without continuous flow (for 

example, Little Cottonwood Creek, Kays 

Creek). Stream temperature was identified as an important factor determining 

the composition of the biological community. Diversions also serve as barriers 

to migration of stream organisms, which 

could reduce diversity.

This study identified some of the 

human-caused factors affecting communities in urban steams along the Wasatch 

Mountains. It is clear that maintaining 

flow in the stream channel is essential 

for the maintenance of biological communities. Reducing water temperatures, 

improving water quality, and reducing runoff of silt into streams will help 

maintain the health of the biological 

community. Such findings may help in 

the development of useful ecological or 

other indicators of the effects of urbanization on stream ecosystems, and the 

uses of these indicators may increase the 

cost effectiveness of monitoring programs.

Elevated concentrations 

of trace elements in 

sediment and water are 

related to natural sources 

and past mining activities 

Minerals in rocks are sources 

of arsenic and radon in ground 

water

Concentrations of arsenic in shallow and basin-fill aquifers in the Great 

Salt Lake Basins Study Unit were highly 

variable, ranging from less than 0.4 

to 95 μg/L, with a median of 2.1 μg/L 

(fig. 36). Arsenic, a naturally occurring 

trace element in ground water within the 

Study Unit, is derived from geochemical 

reactions with certain types of minerals. 

Tertiary volcanic rocks and the Salt Lake 

Formation exposed near the base of the 

Oquirrh Mountains may be a source of 

arsenic on the western side of the Salt 

Lake Valley that is not present on the 

eastern side. Water from wells in the 

western and northwestern parts of the 

valley generally had higher arsenic 

concentrations than water from wells in 

other areas. The median concentration 

of arsenic in water from relatively shallow monitoring wells, many of which 

Some of the trace element concentrations in sediment and 

fish tissue at urban sites were greater than concentrations for 

many urban sites nationwide

Streambed sediment concentrations in Red Butte Creek, a reference site for study unit streams, were 

greater than the NAWQA national 

median for cadmium, chromium, 

selenium, and silver in urban streams. 

This may indicate that the streams 

in the Great Salt Lake Basins Study 

Unit have relatively higher natural 

background concentrations than those 

found nationally. Trout livers from 

Red Butte Creek in Jordan River Basin 

exceeded the national 90th percentile (fig. 35) concentration for nickel 

and exceeded the national median 

concentrations for arsenic, cadmium, 

mercury, and selenium. Concentrations of trace elements at two sites 

on the Jordan River and two sites on 

Little Cottonwood Creek, an urban 

tributary of the Jordan 

River, greatly exceeded 

the national median 

values in both sediment 

and fish tissue. In Little 

Cottonwood Creek, 7 of 

10 elements in bed sediment were greater than 

the national 90th percentile concentration. 

In fish-tissue samples 

from Little Cottonwood 

Creek, 5 of 10 elements 

exceeded the national 90th percentile. 

Arsenic in particular was substantially 

elevated above the 90th percentile. 

These exceedances are believed to be 

due mostly to historical mining activities before the area became highly 

urbanized. 

Figure 35. Trace-element concentrations in bed sediment and fish 

tissue in the Great Salt Lake Basins 

exceeded the 90th percentile concentration of the NAWQA Program 

dataset.

0

1

2

3

4

5

6

7

8

1 2 4 5 19 10 11 213 15 16 17 18 19

NUMBER OF TRACE ELEMENTS GREATERTHAN 90th PERCENTILE CONCENTRATION

OF NATIONAL NAWQA DATA SET

9

SITE NUMBER

Bear River Basin Weber River Basin Jordan River Basin

Sediment

Fish tissue, liver

Fish tissue, whole

body

1 No fish tissue sample collected at this site. 2 No sediment sample collected at this site.

16 17 18

Figure 36. Arsenic concentrations 

exceeded the USEPA drinking-water 

standard in about 20 percent of samples 

collected from the basin-fill aquifers. ARSENIC CONCENTRATION, IN MICROGRAMS PER LITER 0.1

1

10

21

4

5

21 Number of samples at or

below this concentration

Wells sampled

throughout

study area

Salt Lake Valley

public-supply

wells

Salt Lake

Valley

Deeper basin-fill

aquifers

Shallow

aquifer

100

Median

USEPA

drinking-water

standard

Median

of all

sampled

wells
22 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

are on the western side of the valley, was 

7.3 μg/L, with 43 percent of the samples 

exceeding the USEPA drinking-water 

standard of 10 μg/L. Concentrations of 

arsenic were generally lower in water 

from public-supply wells completed in 

the basin-fill aquifer underlying the valley (median of 1.1 μg/L with 16 percent 

exceeding the standard) because many 

of these wells are on the eastern side of 

the valley. About 20 percent of the wells 

sampled in the recharge areas of the 

basin-fill aquifers throughout the Study 

Unit exceeded the drinking-water standard. Water from most wells sampled 

is used for domestic supply (provides 

drinking water to a small number of 

families). The Safe Drinking Water Act 

does not regulate domestic wells and 

therefore homeowners may not be aware 

of possible risks associated with elevated 

arsenic concentrations in their wells.

Radon occurs naturally as a gas 

that is soluble in ground water and is 

released through radioactive decay 

from rocks containing uranium. Higher 

amounts of radon occur in areas with 

uranium-rich sources such as granite, 

metamorphic rocks, and basin-fill deposits weathered from these rocks. Because 

of a short half-life of 3.8 days, radon 

is detected only near its source. Radon 

moves easily through highly permeable 

material, such as sand, gravel, and fractures; and readily degasses from water 

exposed to air. 

Radon occurred commonly at 

elevated concentrations in shallow 

and basin-fill aquifers underlying the 

Great Salt Lake Basins Study Unit, 

with a median of 667 pCi/L (picocuries 

per liter). Most samples (95 percent) 

exceeded the USEPA proposed drinking-water standard of 300 pCi/L, but 

none exceeded the alternative standard 

of 4,000 pCi/L. Radon concentrations 

greater than 2,000 pCi/L measured 

in three water-supply wells in Davis 

County are likely the result of their 

proximity to metamorphic rocks in 

the Wasatch Mountains. The mountain block and basin-fill deposits in the 

southeastern part of Salt Lake Valley 

are composed primarily of uraniumbearing rocks, resulting in radon concentrations greater than 1,000 pCi/L in 

water from monitoring and publicsupply wells in the area. 

Past mining activities contribute 

to elevated levels of trace elements in sediment and water

Trace elements are elevated in sediment and water in Silver Creek, Weber 

River below Silver Creek, and Echo Reservoir, largely because of historical mining for silver and lead ores in the headwaters of the Silver Creek drainage 

through the 1970s (fig. 37). Specifically, concentrations of arsenic and lead 

in bed sediment were more than 10 times 

higher in the Weber River below Silver 

Creek than in the Weber River above 

the creek (fig. 38). Enrichment in Echo 

Reservoir as well as at sites on the Weber 

River below Silver Creek is largely due 

to inflow from the creek. Concentrations 

of cadmium, copper, selenium, silver, 

and zinc also were elevated, but concentrations of chromium and nickel in bed 

Breathing radon in indoor air is the second 

leading cause of lung cancer and is a greater 

health concern than drinking water that contains 

radon. Most of the risk from radon in water is 

from breathing radon released to indoor air from 

household water uses. The USEPA proposed rule 

for radon allows States and community water 

systems to use a higher alternative drinking-water 

standard if they implement a program to address 

radon risks in indoor air (U.S. Environmental Protection Agency, 1999).

Figure 37. Mining in the Silver Creek and Little Cottonwood Creek watersheds has 

increased concentrations of arsenic and other trace elements in the water and sediment 

of these streams. 

EXPLANATION

Historical mining

site

Historical smelter

site

Sampling site and

number

80

80 84

0 15 KILOMETERS

0 15 MILES

112°

111°

Great

 Salt

 Lake

Weber River

Ogden

Salt

Lake

City

Rockport

Reservoir

East

Canyon

Reservoir

Pineview

Reservoir

Echo

Reservoir

River

Weber

Creek

Silver

IDAHO WYOMING

UTAH

10

10

40°35'

41°20'

Little

Cottonwood Cr

8

6

5

7

1

3

10

9

4

3

2

5

5
Major Findings 23

sediments did not appear to be greater 

downstream from mining-affected areas. 

The concentrations of some metals 

were elevated in the water of streams 

draining areas with historical mining 

and ore smelting. For example, zinc concentrations in water samples from Silver 

Creek ranged from 90 to 

1,800 μg/L, exceeding the USEPA 

aquatic-life criterion (adjusted for hardness) in four of eight samples. Aquatic 

macroinvertebrate communities at sites 

in upper Silver Creek with high zinc 

concentrations were impaired (low species richness and a higher percentage of 

tolerant taxa) relative to other sites in the 

area with lower concentrations of zinc 

(Giddings and others, 2001). Streams 

draining basins with little or no mining 

activity, such as those in the Bear River 

Basin, generally had low concentrations of dissolved metals. For example, 

zinc concentrations in water samples 

from Bear River sites ranged from 2 to 

7 μg/L. 

Mercury, used from the 1880s to 

early 1900s to process lead and silver 

ores in the Park City mining district, 

was detected in water and bed-sediment 

samples from Silver Creek at concentrations exceeding various aquatic-life 

guidelines (Giddings and others, 2001). 

Total mercury concentration in streambed sediment from three sites on Silver 

Creek (sites 2, 3, and 4, fig. 37) and one 

site on the Weber River (site 6, fig. 37) 

ranged from about 1,000 to 27,000 

μg/kg, far exceeding the Canadian 

guideline of 486 μg/kg, designed to 

protect aquatic life (Canadian Council 

of Ministers of the Environment, 2002). 

Although concentrations of total dissolved mercury in water were below the 

USEPA chronic aquatic-life criterion 

(770 nanograms per liter), methylmercury concentrations in water exceeded 

the USEPA chronic criterion for fisheating wildlife (0.05 nanogram per 

liter) (National Irrigation Water Quality Program, 1998). Methylmercury is 

readily available for biological uptake 

and has been shown to biomagnify in 

the food chain (Eisler, 1987). Thus, even 

small amounts of methylmercury in the 

environment can be harmful to biota that 

feed on aquatic prey. 

The concentration of arsenic measured in water samples from lower Little 

Cottonwood Creek (site 10, fig. 37) 

ranged from 4.7 to 284 μg/L, exceeding 

the USEPA aquatic-life criterion of 

150 μg/L in 8 of 49 water samples. 

Sources of arsenic in Little Cottonwood 

Creek include imported water from the 

Utah Lake Basin and, most notably, 

runoff from historical smelter sites. The 

August 1999 synoptic study of trace elements in lower Little Cottonwood Creek 

identified the area near the historical 

Murray smelter site as the major source 

of arsenic (fig. 39). Reclamation has 

been done at this site; however, surface 

and subsurface flow near the site still 

appears to be contributing dissolved 

arsenic to the stream. 

Streams in basins with little or no 

mining had arsenic concentrations less 

than 3 μg/L. The metals in the water 

and sediment of many of the miningaffected streams of the Great Salt Lake 

Basins Study Unit probably will persist 

for many years.

Increases in levels of trace 

elements in sediment since the 

mid-19th century are related to 

smelter emissions 

Trace-element concentrations first 

began to increase in sediment deposited 

in Mirror Lake and Farmington Bay of 

Great Salt Lake in 1870, with a substantial increase occurring after 1900. Mirror 

Lake is in the Uinta Mountains, approximately 50 miles east of Salt Lake City. 

The surface sediments of cores taken 

from Mirror Lake had higher concentrations of arsenic, cadmium, copper, 

lead, tin, and zinc, relative to the deeper 

sediments (fig. 40). Age dating of a 

core collected in 1998 from Farmington 

Bay (Naftz and others, 2000) indicated 

a lead profile (fig. 29) similar to that 

determined for Mirror Lake (fig. 40). 

In the Farmington Bay core, the profile indicates that lead contamination 

began to increase after about 1842 and 

made the most marked increase between 

about 1916 and 1950. Due to the 

remote location of Mirror Lake, it was 

concluded that the increases in metal 

concentrations over time are related to 

atmospheric deposition from smelter 

activities. Large-scale mining and smelting of nonferrous metal ores began in 

the Wasatch Mountains and adjacent 

valleys after 1868, which would have 

contributed metals to the atmosphere. 

Industrial and energy-related sources in 

the Salt Lake City area also would have 

contributed metals to the atmosphere, 

and growth of these industries occurred 

after 1900. These dates coincide with 

increases in metal concentrations of the 

cores. In addition, lead concentrations 

in cores correspond to lead emissions 

from vehicles and other combustion 

sources.

0

10

20

30

40

50

60

70

1 5 7 8 0

200

400

600

800

1,000

1,200

1,400

1,600

1,800

ARSENIC CONCENTRATION, IN

MICROGRAMS PER GRAM OF SEDIMENT

LEAD CONCENTRATION, IN MICROGRAMS PER GRAM OF SEDIMENT

Silver Creek

6

Arsenic

Lead

WEBER RIVER SITES

Figure 38. Inflow from Silver Creek 

greatly enriches the concentration of trace 

elements in the sediments of Weber River 

and Echo Reservoir. From the mid-1800s 

through the 1970s, the headwaters of the 

Silver Creek drainage were extensively 

mined for silver and lead ores (see fig. 37 

for site locations). 

Figure 39. Dissolved arsenic concentration in water samples from Little Cottonwood Creek, August 1999, were greatest 

at sites adjacent to and downstream from 

historical ore-smelting sites.

0

10

20

30

40

50

Downstream

Minimum

Reporting

Level (1 μg/L)

Crestwood ParkCanal inflow Smelter site

ARSENIC CONCENTRATION,

IN MICROGRAMS PER LITER
24 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

In areas with mining-related 

activities, concentrations of trace elements in sediment often exceeded the 

Probable Effect Concentration (PEC) 

values (Waddell and Giddings, 2003). 

The PEC represents the concentration 

in bulk sediments above which adverse 

biological effects are likely to occur 

(MacDonald and others, 2000). The 

upper Weber River Basin, and the Utah 

Lake-Jordan River Basin were the most 

extensively mined areas and the Bear 

River Basin the least mined. 

 The most heavily affected streams 

sampled were Little Cottonwood Creek, 

Silver Creek, and the Weber River 

below the Silver Creek confluence. 

Concentrations at two sites on Silver 

Creek and at a site on the Weber River 

below the confluence with Silver Creek 

exceeded the PEC levels for arsenic, 

cadmium, copper, lead, mercury, silver, 

and zinc. Concentrations at two sites on 

Little Cottonwood Creek, as well as at a 

site on the Jordan River below the confluence with Little Cottonwood Creek, 

exceeded the PEC levels for arsenic, 

cadmium, copper, lead, silver, and zinc.

In areas with very little mining, no 

PEC levels were exceeded. None of the 

concentrations in samples from the 15 

sites sampled exceeded the PEC levels 

for chromium and nickel, and concentrations at only one site on Silver Creek 

exceeded the PEC for selenium. 

NAWQA samples represent the 

fine-grained fraction of bed sediment 

only (less than 63 micrometers), which, 

in general, contains higher concentrations of trace elements than bulk sediment. The guidelines of MacDonald 

and others (2000) are intended for bulk 

sediment; thus, results from NAWQA 

samples may somewhat overstate the 

problem based on bulk-sediment criteria, and caution should be used in 

applying the criteria to values close to 

the PEC.

Trace elements in sediments exceed Probable Effect 

Concentrations only in areas with 

mining-related activities 

Jordan River Basin

1 From protocol for aquatic hazard assessment of

selenium (Lemly, 1995).

2 From Long and others, 1995.

0.01

1

100

10,000

Bear River Basin

33.0

4.98

111 149 128

1.06

48.6

14

21.0

459

0.01

1

100

10,000

100,000

0.01

1

100

10,000

CONCENTRATION, IN MICROGRAMS

PER GRAM, DRY WEIGHT

Arsenic

Cadmium

Chromium

Copper

Lead

Mercury

Nickel

Selenium

Silver

Zinc

Weber River Basin

Probable

Effect

Concentration

Arsenic

Cadmium

Chromium

Copper

Lead

Mercury

Nickel

Selenium

Silver

Zinc

0.1

0.1

0.1

10

10

10

1,000

1,000

1,000

Figure 40. Metals concentration in sediment core from Mirror Lake began increasing 

after about 1870. Due to the remote location and absence of mining in the watershed 

upstream from the lake, the metal enrichment is believed to be due to atmospheric deposition from mining-related activities. Data from Kada and others (1994, fig. 7).

CONCENTRATION, IN MICROGRAMS PER GRAM

DEPTH, IN INCHES

50 100 150

Lead

0

4

8 1.0 2.0

Cadmium

20 40 60

Copper

50 100 150

Zinc

1982

1963

1932

1862

1796

1723

1902

0.5 1.0 2.0

Tin

20 30 1.5

Arsenic

10
Study Unit Design

25

Stream Chemistry

Surface-water samples were collected monthly from 10 sites on 6 streams to measure 

quality and to assess the effects of land use and hydrogeologic setting on water quality 

(Baskin and others, 2002). Sites 3, 8, and 10 were sampled more often to determine seasonal 

variability and to test for pesticides and volatile organic compounds. About 100 additional 

sites throughout the Study Unit were sampled once or twice to further assess the occurrence 

and distribution of nutrients, pesticides, or trace elements in streams. 

Stream Ecology

Ecological assessments were completed at 

sites frequently sampled for stream chemistry to 

define existing biological conditions. Some of the 

assessments examined multiple reaches of a stream 

to determine spatial variations in the habitat and 

community structure. Broad, one-time snapshot 

assessments (referred to as synoptic studies) were 

designed to further examine spatial variability in 

biological communities. Bed sediment and fish 

tissue were sampled at selected sites.

Ground-Water Chemistry

Ground-water samples were collected from wells in basinfill aquifers used for drinking-water supply or from wells in the 

overlying shallow aquifer that has the potential to recharge the 

deeper aquifers. Water-supply wells were sampled to assess the 

water quality of the deeper aquifers in recharge areas across the 

Great Salt Lake Basins. Monitoring wells installed in the shallow 

ground-water system in Salt Lake Valley (including the flow-path 

study areas) were sampled to 

determine the effects of land 

use on water quality. Publicsupply wells in Salt Lake 

Valley also were sampled to 

characterize the quality of 

water in the aquifer used for 

drinking water in an urban 

area.

Site number Site name Site type Basin area

(square miles)

Site number Site name Site type Basin area

(square miles)

1 Bear River below Smiths Fork, near Cokeville, 

Wyoming

Rangeland 2,444 6 Weber River near Plain City, Utah Mixed/Urban 2,072

2 Bear River at Pescadero, Idaho Rangeland 3,699 7 Little Cottonwood Creek at Crestwood Park, at 

Salt Lake City, Utah

Urban 36

3 Cub River near Richmond, Utah Agriculture 222 8 Little Cottonwood Creek at Jordan River, near 

Salt Lake City, Utah

Urban 45

4 Bear River near Corinne, Utah Mixed/

Rangeland

7,065 9 Red Butte Creek at Fort Douglas, near Salt Lake 

City, Utah

Forest 7.21

5 Weber River near Coalville, Utah Forest 427 10 Jordan River at Salt Lake City, Utah Mixed/Urban 3,508

Urban area

Monthly sampling

site and number

Jordan

Provo

River

Bear

Weber

Bear River

River

42�

112� 111�

7

EXPLANATION

Great

 Salt

 Lake

0

0 25 50 KILOMETERS

25 50 MILES

1

2

3

4

6

5 9

7

8 10

41�

40�

UTAH

IDAHO

River

Utah

Lake

Bear

Lake

WYOMING

River

WYOMING

42�

41�

112� 111�

UTAH

IDAHO

40�

EXPLANATION

River

River

River

Provo River

Jordan River

Utah

Lake

Bear

Bear

River

Bear

Weber

Bear

Lake

0

0 25 50 KILOMETERS

25 50 MILES

Great

 Salt

 Lake

Type of sampling site

Ecological, single

reach, single year

Ecological, multiple

reach, multiple year

Bed sediment and

tissue occurrence

Bed sediment and

tissue distribution

Note: Symbol for site may

be divided to represent a

multiple-type site

40°

30'

40°

45'

112°07'30"

111°48'

EXPLANATION

Approximate

boundary of basinfill deposits

0 3 6 KILOMETERS

0 3 6 MILES

Jordan

Provo

River

Bear

Weber

Bear River

River

42°

112° 111°

Great

 Salt

 Lake

0

0 25 50 KILOMETERS

25 50 MILES

41°

40°

UTAH

IDAHO

River

Utah

Lake

Bear

Lake

WYOMING

River

Jordan River

Salt Lake

Valley

Area of Salt Lake Valley

Flow-path study area

Type of study well

Urban land overlying shallow

ground water

Public supply

Basin-fill aquifers in recharge

areas
26 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998–2001

Study

Component What data are collected and why Number and types of sites sampled Sampling frequency and period

Stream Chemistry

Streams and Rivers Physical parameters (streamflow, dissolved oxygen, pH, alkalinity, specific conductance, temperature), nutrients, major ions, organic carbon, and suspended 

sediment. To measure how often and how much of a constituent is found, over 

time, given seasonal changes or land use.

Ten sites representing urban development, agriculture, forest 

and rangeland, and mixed land use.

Monthly and during selected 

runoff events. October 1998 to 

September 2000

Streams and Rivers, 

Intensive Sampling

Same as above but sampled more frequently and for pesticides and VOCs. To 

measure how often and how much of a constituent is found, over time, given 

seasonal changes or land use.

Includes three of the above sites. One site representing urban 

development, one site representing agriculture, and one site 

representing mixed, but predominately urban land use.

Weekly to monthly and during 

selected runoff events. March 

1999 to September 2000

Urban Stream Study Physical parameters, trace elements, nutrients, and pesticides. Used a 

bromide tracer to determine streamflow sources. To measure how much a 

constituent concentration changes over the area due to different land- or 

chemical-use patterns.

Study done in Little Cottonwood Creek. Bromide tracer was 

sampled at 97 sites, trace elements were sampled at 24 sites, 

and nutrients and pesticides were sampled at 4 sites.

Once. August 31 or September 

2, 1999

Agricultural Stream 

Study

Physical parameters, nutrients, major ions (July and August only), sediment, 

turbidity, and pesticides (not collected at all sites). To measure how much 

a constituent concentration changes over the area due to different land- or 

chemical-use patterns.

Study conducted in the Bear River drainage and included the 

main stem of the Bear River and tributaries of the Bear River. 

Sixty-five sites were sampled.

Twice. A 2-week period in 

March 2001 and a 2-week 

period in July/August 2001

Mining Stream Study Physical parameters, trace elements in water and sediment, and invertebrate 

community samples. To measure mining impacts on stream chemistry and the 

aquatic community.

Study conducted in the Park City/upper Weber River area and 

included 10 sites.

Twice. March 2000 (dissolved 

trace elements only) and 

July/August 2000

Stream Ecology

Ecological Studies Physical parameters, fish, macroinvertebrates, and algal communities, and 

habitat characteristics. To describe the water quality of streams by using 

species assemblages and to examine how they vary in relation to different 

physical and chemical conditions.

Ten sites representing urban development, agriculture, forest 

and rangeland, and mixed land use (same sites as in Streams 

and Rivers study component). 

Six sites were sampled once 

and four sites were sampled 3 

consecutive years, July-August 

1999–2001 

Flow-Regime Study Physical parameters and macroinvertebrate communities. To examine effects 

of hydrologic alterations on macroinvertebrate communities. 

Fourteen sites along the main stem of the Bear River. Sampled in August 2001

Bed-Sediment and 

Tissue Studies

Physical parameters, pesticides, other synthetic organic compounds, and trace 

elements in streambed sediment and in fish tissue. To determine occurrence 

and distribution of potentially toxic compounds in sediment and fish tissue at 

selected sites.

Study was conducted at 19 sites. Once. Twelve sites were 

sampled during August-September 1998. Seven sites 

were sampled during July 1999

Ground-Water Chemistry

Shallow Ground 

Water Underlying 

Urban Areas in Salt 

Lake Valley

Physical parameters, major ions, selected trace elements, pesticides, VOCs, 

nutrients, radon, and stable isotopes. Selected samples to estimate groundwater ages using tritium, helium-3, and CFCs. To examine how land use in an 

urban area affects the quality of ground water in recently recharged shallow 

aquifers.

Installed 30 monitoring wells in the shallow ground-water 

system underlying recently developed (less than 30 years) 

residential and commercial areas in Salt Lake Valley, Utah.

Sampled once in summer 1999

Basin-Fill Aquifers 

Study

Physical parameters, major ions, selected trace elements, pesticides, VOCs, 

nutrients, radon, stable isotopes, and tritium. To characterize the water quality 

in the basin-fill aquifers that are most important for present and future use in 

the study area.

Included 55 wells (mostly used for domestic supply) in the 

recharge areas for the deeper basin-fill aquifers within the 

Great Salt Lake Basins. 

Sampled once during JulyNovember 1998

Ground-Water FlowPath StudyPhysical parameters, major ions, selected trace elements, pesticides, VOCs, 

nutrients, radon, and stable isotopes. Selected samples to estimate groundwater ages using tritium, helium-3, and CFCs. To characterize shallow groundwater quality in relation to ground-water flow in a residential area.

Installed 11 monitoring wells along 2 hypothetical flow paths 

in residential areas in Salt Lake Valley, Utah. Sampled the 

monitoring wells, 6 nearby existing wells (including 3 land-use 

study wells) and 1 nearby stream.

Sampled 17 sites in spring 

2000. Sampled or resampled 

13 sites in fall 2000

Public-Supply Well 

Study

Physical parameters, major ions, selected trace elements, pesticides, VOCs, 

nutrients, radon, stable isotopes, and methylene blue active substances. 

Selected samples to estimate ground-water ages using tritium, helium-3, and 

CFCs. To characterize water quality in the principal aquifer used for public 

supply in an urban area.

Included 31 public supply wells, 15 of which represent the 

largest producers in Salt Lake Valley, Utah.

Sampled once during MayJune 2001

Special Studies

Land-Use Gradient 

Study 

Physical parameters, fish, macroinvertebrates, and algal communities, and 

habitat characteristics, nutrients, major ions (July sample only), and pesticides. 

To examine relations between varying levels of land-use intensity and water 

quality using biological, physical, and chemical responses.

Sampled 1 to 3 sites on 13 streams and rivers along the 

western side of the Wasatch Mountains. A total of 28 sites 

were sampled.

Twice during 2000, in spring 

and summer

Trend Analysis from 

Sediment Cores

Analyzed sediment cores for trace elements, selected organic compounds, and 

cesium-137 (for age dating). To reconstruct the history of contaminant flux 

from runoff and atmospheric deposition during the past several decades of 

urban and industrial growth.

Sampled at three depositional sites along the western side of 

the Wasatch Mountains. Red Butte Reservoir, representing an 

undeveloped site, Farmington Bay, representing a mixed site, 

and Decker Lake, representing an urban site.

Sampled once in 1998
References Cited

The Great Salt Lake Basins publications are shown in bold 

type.

Baskin, R.L., Thiros, S.A., Giddings, E.M., Hadley, H.K., 

Gerner, and S.J., 2002, Water-quality assessment of the 

Great Salt Lake Basins, Utah, Idaho, and Wyoming—

Environmental setting and study design: U.S. Geological 

Survey Water-Resources Investigations Report 02–4115, 

47 p.

Björseth, A., Ramdahl, T., eds., 1985, Handbook of polycyclic 

aromatic hydrocarbons, Volume 2, Emission sources and 

recent progress in analytical chemistry: New York, Marcel 

Dekker, Inc., 1985.

Callender, E., and Van Metre, P.C., 1997, Reservoir sediment 

cores show U.S. lead declines: Environmental Science and 

Technology, v. 31, no. 9, p. 424–428.

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Quality Section, Guidelines Division, 52 p.

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(PAHs) in the terrestrial environment—A review: Journal of 

Environmental Quality, v. 12, no. 4, p. 427–441. 

Eisler, R., 1987, Mercury hazards to fish, wildlife, and invertebrates—A synoptic review: U.S. Fish and Wildlife Service, 

Patuxent Wildlife Research Center, Biological Report 85 

(1.10), 81 p.

Environment Canada and Health Canada, 2001, Canadian 

Environmental Protection Act, 1999, Priority substances 

list assessment report—Road salts: Government of Canada, 

170 p.

Gerner, S.J., 2003, Water quality at fixed sites in the 

Great Salt Lake Basins, Utah, Idaho, and Wyoming, 

water years 1999–2000: U.S. Geological Survey WaterResources Investigations Report 03–4236.

Gerner, S.J., and Waddell, K.M., 2003, Hydrology and 

water quality of an urban stream reach in the Great 

Basin—Little Cottonwood Creek near Salt Lake City, 

Utah, water years 1999–2000: U.S. Geological Survey 

Water-Resources Investigations Report 02–4276, 46 p.

27

Giddings, E.M., Hornberger, M.I., and Hadley, H.K., 

2001, Trace-metal concentrations in sediment and water 

and health of aquatic macroinvertebrate communities of streams near Park City, Summit County, Utah: 

U.S. Geological Survey Water-Resources Investigations 

Report 01–4213, 22 p.

Hitt, K.J., 1994, Refining 1970s land-use data with 1990 population data to indicate new residential development: U.S. 

Geological Survey Water-Resources Investigations Report 

94–4250, 15 p.

Holden, P.B., Zucker, S.J., Abate, P.D., and Valdez, R.A., 

1996, Assessment of the effects of fish stocking in the State 

of Utah past, present, and future: Prepared by BIO/WEST, 

Inc., for the Utah Division of Wildlife Resources, Logan, 

Utah, 104 p.

Kada, J., Heit, M., and Miller, K.M., 1994, Chronology of 

anthropogenic trace element input to four Utah Lakes reconstructed using sediment cores: Water, Air, and Soil Pollution, v. 75, p. 353–369.

Lemly, A.D., 1995, A protocol for aquatic hazard assessment 

of selenium: Journal of Ecotoxicology and Environmental 

Safety, v. 32, no. 3, p. 280–288. 

Long, E.R., MacDonald, D.D., Smith, S.L., and Calder, F.D., 

1995, Incidence of adverse biological effects within ranges 

of chemical concentrations in marine and estuarine sediments: Environmental Management, v. 19, p. 81–97.

Long, E.R., and Morgan, L.G., 1991, The potential for biological effects on sediment-sorbed contaminants tested in the 

National Status and Trends Program: U.S. National Oceanic 

and Atmospheric Administration Technical Memo NOS/

OMA 52, 175 p.

Lopes, T.J., and Bender, D.A., 1998, Nonpoint sources of 

volatile organic compounds in urban areas—Relative 

importance of urban land surfaces and air: Environmental 

Pollution, v. 101, p. 221–230.

MacDonald, D.D., Ingersoll, C.G., and Berger, T.A., 2000, 

Development and evaluation of consensus-based sediment 

quality guidelines for freshwater ecosystems: Archives of 

Environmental Contamination and Toxicology, v. 39, 

p. 20–31.

McMahon, G., and Cuffney, T.F., 2000, Quantifying urban 

intensity in drainage basins for assessing stream ecological conditions: Journal of the American Water Resources 

Association, v. 36, no. 6, p. 1247–1261.
28 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998-2001

Naftz, D.L., Stephens, D.W., Callender, E., and Van Metre, 

P.C., 2000, Reconstructing historical changes in the environmental health of watersheds by using sediment cores 

from lakes and reservoirs in Salt Lake Valley, Utah: U.S. 

Geological Survey Fact Sheet FS–164–00, 5 p.

National Irrigation Water Quality Program, 1998, Guidelines for interpretation of the biological effects of selected 

constituents in biota, water, and sediment: U.S. Department 

of the Interior National Irrigation Water Quality Program 

Information Report No. 3, 198 p.

Paul, M.J., and J.L. Meyer, 2001, Streams in the urban landscape: Annual Review of Ecological Systematics, v. 32, 

p. 333–365.

Sigler, W.F., and Sigler, J.W., 1996, Fishes of Utah, a natural 

history: Salt Lake City, University of Utah Press, 375 p.

Stevenson, R.J., Bothwell, M.L., and Lowe, R.L., eds., 1996, 

Algal Ecology: San Diego, Academic Press, 758 p. 

Thiros, S.A., 2003a, Hydrogeology of shallow basin-fill 

deposits in areas of Salt Lake Valley, Salt Lake County, 

Utah: U.S. Geological Survey Water-Resources Investigations Report 03–4029, 24 p.

Thiros, S.A., 2003b, Quality and sources of shallow ground 

water in areas of recent residential development in Salt 

Lake Valley, Salt Lake County, Utah: U.S. Geological 

Survey Water-Resources Investigations Report 03–4028, 

74 p.

Thiros, S.A., and Manning, A.H., 2004, Quality and 

sources of ground water used for public supply in Salt 

Lake Valley, Salt Lake County, Utah, 2001: U.S. Geological Survey Water-Resources Investigations Report 

03–4325. 

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accessed April 8, 2003, at URL http://www.epa.gov/

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U.S. Environmental Protection Agency, 2000, Ambient water 

quality criteria recommendations—Information supporting the development of state and Tribal nutrient criteria for 

lakes and reservoirs in Nutrient Ecoregion III: U.S. Environmental Protection Agency Report EPA 822–B–00–016, 

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June 20, 2003, at URL http://www.epa.gov/ost/standards/

wqcriteria.html

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 29

Glossary

Algae—Chlorophyll-bearing nonvascular, primarily aquatic 

species that have no true roots, stems, or leaves; most algae 

are microscopic, but some species can be as large as vascular 

plants. 

Aquatic-life guidelines—Water-quality guidelines for protection of aquatic life. Often refers to U.S. Environmental Protection Agency water-quality criteria for protection of aquatic 

organisms. 

Aquifer—A water-bearing layer of soil, sand, gravel, or rock 

that will yield usable quantities of water to a well. 

Atmospheric deposition—The transfer of substances from the 

air to the surface of the Earth, either in wet form (rain, fog, 

snow, dew, frost, hail) or in dry form (gases, aerosols, particles). 

Background concentration—A concentration of a substance in 

a particular environment that is indicative of minimal influence 

by human (anthropogenic) sources. 

Biota—Living organisms. 

Chlorofluorocarbons—A class of volatile compounds consisting of carbon, chlorine, and fluorine. Commonly called freons, 

which have been used in refrigeration mechanisms, as blowing 

agents in the fabrication of flexible and rigid foams, and, until 

several years ago, as propellants in spray cans. 

Community—In ecology, the species that interact in a common 

area. 

Concentration—The amount or mass of a substance present in 

a given volume or mass of sample. 

Confined aquifer (artesian aquifer)—An aquifer that is completely filled with water under pressure and that is overlain by 

material that restricts the movement of water. 

Confining layer—A layer of sediment or lithologic unit of low 

permeability that bounds an aquifer.

Confluence—The flowing together of two or more streams; the 

place where a tributary joins the main stream. 

DDT—Dichloro-diphenyl-trichloroethane. An organochlorine 

insecticide no longer registered for use in the United States. 

Degradation products—Compounds resulting from transformation of an organic substance through chemical, photochemical, and/or biochemical reactions. 

Dissolved solids—Amount of minerals, such as salt, that are 

dissolved in water; amount of dissolved solids is an indicator 

of salinity or hardness. 

Drinking-water standard or guideline—A threshold concentration in a public drinking-water supply, designed to protect 

human health. As defined here, standards are U.S. Environmental Protection Agency regulations that specify the maximum contamination levels for public water systems required 

to protect the public welfare; guidelines have no regulatory 

status and are issued in an advisory capacity. 

Ecoregion—An area of similar climate, landform, soil, 

potential natural vegetation, hydrology, or other ecologically 

relevant variables. 

Eutrophication—The process by which water becomes 

enriched with plant nutrients, most commonly phosphorus and 

nitrogen. 

Habitat—The part of the physical environment where plants 

and animals live. 

Invertebrate—An animal having no backbone or spinal column. 

Major ions—Constituents commonly present in concentrations 

exceeding 1.0 milligram per liter. Dissolved cations generally 

are calcium, magnesium, sodium, and potassium; the major 

anions are sulfate, chloride, fluoride, nitrate, and those contributing to alkalinity, most generally assumed to be bicarbonate 

and carbonate. 

Median—The middle or central value in a distribution of data 

ranked in order of magnitude. The median is also known as the 

50th percentile. 

Micrograms per liter (μg/L)—A unit expressing the concentration of constituents in solution as weight (micrograms) of solute per unit volume (liter) of water; equivalent to one part per 

billion in most stream water and ground water. One thousand 

micrograms per liter equals 1 mg/L. 

Midge—A small fly in the family Chironomidae. The larval 

(juvenile) life stages are aquatic. 

Milligrams per liter (mg/L)—A unit expressing the concentration of chemical constituents in solution as weight (milligrams) of solute per unit volume (liter) of water; equivalent 

to one part per million in most stream water and ground water. 

One thousand micrograms per liter equals 1 mg/L. 

Nitrate—An ion consisting of nitrogen and oxygen (NO3

-

). 

Nitrate is a plant nutrient and is very mobile in soils. 

Nonpoint source—A pollution source that cannot be defined 

as originating from discrete points such as pipe discharge. 

Areas of fertilizer and pesticide applications, atmospheric 

deposition, manure, and natural inputs from plants and trees 

are types of nonpoint source pollution. 

Nutrient—Element or compound essential for animal and 

plant growth. Common nutrients in fertilizer include nitrogen, 

phosphorus, and potassium. 

Organochlorine compound—Synthetic organic compounds 

containing chlorine. As generally used, term refers to compounds containing mostly or exclusively carbon, hydrogen, 

and chlorine. Examples include organochlorine insecticides, 
30 Water Quality in the Great Salt Lake Basins, Utah, Idaho, and Wyoming, 1998-2001

polychlorinated biphenyls, and some solvents containing 

chlorine. 

Organochlorine insecticide—A class of organic insecticides 

containing a high percentage of chlorine. Includes dichlorodiphenylethanes (such as DDT), chlorinated cyclodienes (such 

as chlordane), and chlorinated benzenes (such as lindane). 

Most organochlorine insecticides were banned because of their 

carcinogenicity, tendency to bioaccumulate, and toxicity to 

wildlife. 

Pesticide—A chemical applied to crops, rights of way, lawns, 

or residences to control weeds, insects, fungi, nematodes, 

rodents or other “pests.” 

Picocurie (pCi)—One trillionth (10–12) of the amount of radioactivity represented by a curie (Ci). A curie is the amount of 

radioactivity that yields 3.7 • 1010 radioactive disintegrations 

per second (dps). A picocurie yields 2.22 disintegrations per 

minute (dpm) or 0.037 dps. 

Polychlorinated biphenyls (PCBs)—A mixture of chlorinated 

derivatives of biphenyl, marketed under the trade name Aroclor with a number designating the chlorine content (such as 

Aroclor 1260). PCBs were used in transformers and capacitors 

for insulating purposes and in gas pipeline systems as a lubricant. Further sale for new use was banned by law in 1979. 

Point source—A source at a discrete location such as a 

discharge pipe, drainage ditch, tunnel, well, concentrated livestock operation, or floating craft. 

Recharge—Water that infiltrates the ground and reaches the 

saturated zone. 

Riparian—Areas adjacent to rivers and streams with a high 

density, diversity, and productivity of plant and animal species 

relative to nearby uplands. 

Runoff—Excess rainwater or snowmelt that is transported to 

streams by overland flow, tile drains, or ground water. 

Sorption—General term for the interaction (binding or association) of a solute ion or molecule with a solid.

Species—Population of organisms that may interbreed and 

produce fertile offspring having similar structure, habits, and 

functions.

Specific conductance—A measure of the ability of a liquid to 

conduct an electrical current. 

Study Unit—A major hydrologic system of the United States 

in which NAWQA studies are focused. Study Units are geographically defined by a combination of ground- and surfacewater features and generally encompass more than 4,000 

square miles of land area.

Suspended sediment— Particles of rock, sand, soil, and 

organic detritus carried in suspension in the water column, in 

contrast to sediment that moves on or near the streambed. 

Taxon (plural taxa)—Any identifiable group of taxonomically 

related organisms. 

Tolerant species— Those species that are adaptable to 

(tolerant of) human alterations to the environment and often 

increase in number when human alterations occur. 

Trace element—An element found in only minor amounts 

(concentrations less than 1.0 milligram per liter) in water or 

sediment; includes arsenic, cadmium, chromium, copper, lead, 

mercury, nickel, and zinc. 

Volatile organic compounds (VOCs)—Organic chemicals 

that have a high vapor pressure relative to their water solubility. VOCs include components of gasoline, fuel oils, and 

lubricants, as well as organic solvents, fumigants, some inert 

ingredients in pesticides, and some byproducts of chlorine 

disinfection. 
Appendix—Water-Quality Data from the Great Salt Lake Basins 

in a National Context

31

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34 Water Quality in the Great Salt Lake Basins

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Coordination with agencies and organizations in the Great Salt Lake Basins was integral to the 

success of this water-quality assessment. We thank those who served as members of our liaison 

committee. 

Federal Agencies

Bureau of Land Management

Bureau of Reclamation 

Natural Resources Conservation Service 

U.S. Environmental Protection Agency 

U.S. Fish and Wildlife Service (USFWS)

U.S. Department of Agriculture, Forest Service

State Agencies

Idaho Department of Environmental Quality 

Idaho Department of Fish and Game

Idaho Department of Water Resources

Utah Department of Agriculture

Utah Department of Environmental Quality 

Utah Department of Natural Resources

Wyoming Department of Environmental Quality

Wyoming State Engineer’s Office

Local Agencies

Central Utah Water Conservancy District

City of Sandy 

Jordan Valley Water Conservancy District

Salt Lake City Department of Public Utilities 

Salt Lake City Health Department 

Salt Lake County 

Salt Lake Metropolitan Water District 

Weber Basin Water Conservancy District

Universities

University of Utah

Utah State University

Other public and private organizations

Bear Lake Regional Commission

Bear River Commission 

Bear River Water Quality Committee 

Pacificorp/Utah Power

Utah Climate Center 

We thank the following individuals for contributing to this effort. 

Doyle Stevens (USGS, deceased) provided guidance and assistance during study planning and initial data collection.

Heidi Hadley (USGS) designed and guided the surface-water-quality sampling program for the Study Unit from 1998 to 2001. 

David Naftz (USGS) analyzed and interpreted sediment core data. 

Publications Unit staff, Joseph Gardner, Stefanie Dragos, Ellen Hardy, and Connie Allen applied their considerable talents to bring this and other 

Great Salt Lake Basins reports to publication. 

Terry Short and Steve Goodbred (USGS) provided assistance and guidance for the biological data collection and analysis. 

Thomas Cuffney, Jerry McMahon, Mike Meador, Larry Brown, and Stephen Porter (USGS) provided guidance and field assistance for the urban 

gradient study. Rod DeWeese, Larry Shelton, Brian Caskey and Julia Cherry (USGS) assisted in data collection for the urban gradient study.

Bruce Waddell, Elise Boeke, and colleagues from the U.S. Fish and Wildlife Service assisted with electrofishing and tissue studies. 

Susan Brockner, Paul Downhour, Martel Fisher, Pete Haraden, Terry Kenney, Tim McKinney, Aaron Norton, Larry Spangler, Bert Stolp, Shane 

Wright, Briant Kimball, Michael Enright, Lovina Abbott, Cynthia Hayek, Jonathan Huie, Tyler Meadows, Fredi Salahuddin, Courtney Neuffer, 

Russ Hicks, Nate Grossman, Jane Turner (USGS), and Scott Jennings (volunteer) assisted in various aspects of data collection and compilation.

Gail Cordy and Michael Rosen (USGS), Jeff Salt (Great Salt Lake Keeper), Thad Erickson (Cache County Advisory Board), and many NAWQA 

Program staff provided valuable reviews of this report. 

Property owners throughout the Great Salt Lake Basins, for granting permission to access their property and to sample their wells.
Great Salt

Lake

Provo River

River Jordan

Bear River

Salt Lake City

IDAHO

W

Y

O

MIN

G

UTAH

River

Bear River

Weber

Utah

Lake

Bear

Lake Bear

River

Provo

Ogden

Waddell and others— Water Quality in the Great Salt Lake Basins 

U.S. Geological Survey Circular 1236

National Water-Quality Assessment (NAWQA) Program

Great Salt Lake Basins

NAWQA