U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 046-99

October 1999

Utah

Effects of Causeway on Great Salt

Lake

Great Salt Lake is important ecologically and economically. The lake and

its wetlands provide critical wildlife

habitat in an otherwise arid environment. The salts in the lake are a

valuable economic resource and are

extensively mined. The brine shrimp

industry, which depends upon

harvesting shrimp eggs, has recently

experienced decreased harvests

because of the decreasing salinity in

water in the south part of the lake.

The optimum salinity for the reproduction of brine shrimp eggs is

believed to be between 12 and 18

percent. In the past several years,

salinity has decreased to less than 9

percent in the south part and ranged

from about 24 to 26 percent in the

north part. To assist the State of Utah

in making management decisions, the

U.S. Geological Survey (USGS)

developed a numerical model during

the 1970’s and 1980’s for predicting

the water and salt balance for variable

inflow and differing causeway

conveyance properties.

During 1957–59, a permeable rockfill railroad causeway was constructed across Great Salt Lake (fig.

1A). Although two 15-foot-wide

culverts and a 270-foot-wide breach

allow some water to flow through, the

causeway has acted as a partial dike

by dividing the lake into north and

southern parts (fig. 1B). The formerly

free movement of brine, or water with

a high concentration of dissolved

salts, within the lake is restricted by

the causeway and caused substantial

changes to the hydrology, chemistry,

and biology of the lake.

Before construction of the causeway,

the hydrologic and chemical characteristics of Great Salt Lake were

typical of lakes that lack outlet

streams. The lake water was thought

to be well mixed and without temperature stratification. Salt was

thought to condense and precipitate

out of the water column throughout

the entire lake when the lake volume

was small enough for the saturation

level for sodium chloride to be

exceeded.

Since completion of the causeway,

the factor that most affects the water

and salt balance of Great Salt Lake is

exchange of flow through the causeway. Because almost all surfacewater inflow is to the lake’s south

part, the water surface there is at a

higher altitude than that of the north

part. Also, the water in the south part

is less saline than that in the north

part. Brine flows in both directions

through the causeway fill, culverts,

and breach because of the differences

between the water-surface altitudes

and the water density. Less dense

brine from the south flows northward

through the upper rocks and soil of

the causeway, and more dense brine

from the north flows southward

through the lower rocks and soil of

the causeway (fig. 1C). The southward flow sometimes causes a deep

brine layer to form in the lake’s

southern part.

Structural modifications to the

causeway in recent years have

changed the conveyance properties of

the causeway and thereby affected the

salinity of both parts of the lake. The

USGS is recalibrating the water and

salt balance model to reflect these

changes so that the model remains

useful for lake management.

Energy Resources Program

Coal Resource Assessment

The Coal Resource Assessment

shows the distribution and quality of

Figure 1. A and B, locations of the rock-fill railroad causeway across Great Salt

Lake, the culverts, and the breach, and C, brine flow through the causeway.

Great Salt Lake

Promontory Point

Breach

Railroad causeway

West culvert East culvert

Promontory

Mountains

Saline

Lakeside

Lakeside

Mountains 0

0

5

5

10 MILES

10 KILOMETERS

Inset

0 50 100 150

4,210

4,200

4,190

4,180

4,170

4,160

4,150

4,140

4,130

4,120

Approximate water-surface altitude, February 1980 Interface between

brines in south and

north parts

ALTITUDE, IN FEET

North

part

South

part

Lake-bed deposits

Fill

FEET Lakeside

°00'

41°30'

113°00' 112°00'

Saline

Base from U.S. Geological Survey digital data, 1:100,000, 1978, 1979, 1980, 1984

Universal Transverse Mercator projection

zone 12

0

0 10 20 KILOMETERS

10 20 MILES

Great

 Salt

 Lake Inset

South

part

North

part

41

A.

B.

C.

Railroad causeway

North part

South part
science for a changing world

coals in the southern Wasatch Plateau

and the Kaiparowits Plateau. Research into the geologic controls on

the occurrence and quality of the coal

is being conducted on coals that may

be available for development during

the next few decades. Utah is a highpriority State for coal assessment.

The quality of the coal is an important aspect of the assessment; during

processing or use, its sulfur content

and critical trace elements must meet

the standards of the Clean Air Act of

1990. Coal Resource Assessment

studies provide detailed stratigraphic

cross sections with coal correlations,

databases needed to conduct the

assessments, coal-resource calculations, and basin and area geologic

summaries.

Coal Availability and Recoverability

Studies

The availability of environmentally

acceptable and reliable energy

sources at reasonable prices is an

important issue for Federal, State, and

local planners. The USGS and 13

cooperating State geological surveys

have developed a systematic national

effort to collect, analyze, and depict

data that characterize the relation

between restrictions to mining and

the potential for development of the

Nation’s coal resources.

The Utah Geological Survey (UGS)

began the first of several cooperative

projects in the Wasatch Plateau and

Book Cliffs area of Utah in 1996. A

296-square mile area was selected in

the northern Wasatch Plateau area for

State scientists to identify land-use,

environmental, technologic, and

geologic constraints, and, using

geographic information system

modeling, relate these restrictions to

coalbed thickness and depth and

mined-out areas. USGS and UGS

geologists conferred on these coalbed

correlations. The State then estimated

the unrestricted amounts of coal that

remain unmined and are available for

development. In the northern Wasatch

Plateau study area, this amounts to

about 41 percent of the original coal

resource. As the UGS scientists move

on to the next area of study, the Book

Cliffs, they will transfer their digital

files of the northern Wasatch Plateau

area to the USGS. USGS geologists

and engineers will model mine plans,

estimate future mining and washing

losses, and estimate the amount of

potential economically recoverable

coal in the study area.

Preliminary studies indicate that the

amount of coal in the northern

Wasatch Plateau area that can be

profitably mined is less than 20

percent of the total unmined coal in

the area.

Coalbed Methane Studies

The Wasatch Plateau, one of the

newest and, possibly, most productive

coalbed methane areas in the United

States, was chosen for study of the

geologic and hydrologic controls of

coalbed methane. The USGS, in

cooperation with the UGS, River Gas,

Inc., and Texaco, Inc., is studying the

generation, migration, and production

of coalbed methane; study results

may be applicable to other areas. The

controls of occurrence of coalbed

methane are being evaluated through

detailed geologic, geochemical, and

engineering studies; three-dimensional water-flow models, which are

important for methane production, are

being constructed; and water disposal

is being studied.

Oil and Gas Assessment

The USGS Oil and Gas Assessment

Project is assessing the natural gas

endowment of the U. S. Eighteen

priority provinces, including the

Uinta and Piceance areas, are estimated to contain 90–95 percent of the

known and undiscovered natural gas

resources of the U.S.

The project strategy in 1999 is to

define petroleum systems and geologic assessment units in the UintaPiceance basin and assess the undiscovered natural gas resources,

including conventional and continuous resources. This approach integrates all elements of the petroleum

geology of a basin, including source

rock characterization, hydrocarbon

migration, timing of migration and

structural evolution, sequence stratigraphy, and reservoir quality. The

petroleum system will be subdivided

into geologic units and assessed.

Cleanup of Contaminated Ground

Water

Permeable reactive barriers may

provide economical and effective

remediation techniques to clean up

radionuclide-contaminated ground

water that commonly is present near

abandoned mill-tailing piles. The

barriers are permanent, semipermanent, or replaceable units that are

installed across the flow path of a

contaminant plume. The barriers

contain reactive material that degrades or immobilizes contaminants

as ground water flows through them

(fig. 2).

A cooperative demonstration project

of the U.S. Environmental Protection

Agency and the USGS is underway at

Figure 2. A permeable reactive

barrier.

Contaminant

plume

Permeable

reactive barrier

Trench (filled)

Aquifer

 Ground-water flow
Utah

the Fry Canyon site, which is a small

area of uranium-bearing upgrader

tailings in southeastern Utah. Upgrader tailings result from preconcentration of uranium ore before shipping it to a uranium mill for final

processing. This site was selected in

1996 as a long-term field-demonstration site to assess the performance of

selected barriers for removing

uranium and other trace elements

from ground water. Baseline uranium

concentration in water from a well in

the shallow colluvial aquifer ranged

from 60 micrograms per liter (μg/L)

to more than 17,000 μg/L in areas

beneath the tailings. Three barriers

were installed in August 1997.

Reactive materials being used at the

site are zero valent iron (ZVI),

amorphous ferric oxyhydroxide

(AFO), and bone char phosphate

(PO4).

During the first year of sampling,

more than 99.9 percent of the dissolved uranium was removed in the

ZVI barrier, and more than 85 percent

was removed in the AFO and PO4

barriers (fig. 3).

Global Climate Change

In Utah, the USGS Global Change

and Climate History Program focuses

on developing records of past climate

change and on learning how climate

and human activities affect lakes,

vegetation, and the land surface (fig.

4). Utah is particularly susceptible to

the effects of natural and humaninduced changes because it lies on an

important climatic gradient, and

climatic change can produce large

changes in temperature, precipitation,

and wind. Records of past change

from such regions are important for

understanding global climate change

and for estimating the potential

effects of future change on the local

environment. Arid and semiarid

regions make up much of Utah; such

areas are among the most sensitive to

changes in climate and land use.

Information about how climate and

human activities affect weathering,

erosion, and deposition is essential

for understanding the landscape’s

response to changes in climate and

land use over time scales relevant for

land-use decisions.

Records of past climate change are

being derived from studies of Great

Salt Lake and Bear Lake. Lake

sediments contain rock fragments,

minerals formed from lake water, and

biologic remains, which provide a

geologic record of the changing

environment. Studies of present-day

processes provide information used

for interpreting data obtained from

lake sediment cores. These studies are

intended to provide baseline information for assessing the potential effects

of lake-level changes on the urban

area near Great Salt Lake and the

effects of diversion of Bear River

water into Bear Lake.

Biological Soil Crusts

The USGS is studying biological soil

crusts (fig. 5) in arid ecosystems at

the Canyonlands Field Station. The

crusts, which are critical to ecosystem

functioning in arid lands, are composed of mosses, lichens, and a group

of bacteria called “cyanobacteria.”

The crusts are found throughout the

world, particularly in arid and semiFigure 3. The average 1-year decrease in uranium concentration after passing

through the permeable reactive barriers at Fry Canyon.

AFO

PO4

ZVI

>99.9%

AFO

88.1%

PO

94%

4

Average uranium concentration

 9,770 micrograms per liter

Average uranium concentration

 785 micrograms per liter

Percent of uranium removed

Zero-valent iron

EXPLANATION

ZVI

94% Amorphous ferric oxyhydroxide

Bone char phosphate

Figure 4. Meteorological station in the

Canyonlands area designed to

monitor wind speed and direction,

temperature, precipitation, and soil

moisture.

Figure 5. Biological soil crust.
Printed on recycled paper

USGS office locations USGS State Representative

2329 W. Orton Cir.

West Valley City, UT 84119-2047

(801) 908-5000

FAX (801) 908-5001

USGS Home Page

http://www.usgs.gov

Reports and products

1-888-ASK-USGS

The USGS has 93

employees in Utah

Cedar City

Logan

Moab

Salt Lake City

Monticello

St. George

arid ecosystems such as those prevalent in the southwestern U.S.

The crusts affect soil stability, water

infiltration, and soil fertility. For

example, their sticky surfaces glue

soil particles together, making soil

aggregates larger. These larger

particles are less susceptible than

smaller particles to wind and water

erosion. The roughened surface of the

crusts also affects the moisture

content of desert soils by slowing

overland flow of precipitation,

thereby increasing water infiltration

into desert soils. Crustal organisms

contribute nitrogen and organic

matter to ecosystems.

Because of the significant contribution of biological crusts to ecosystem

functioning, it is important to understand how environmental factors

influence the distribution and abundance of different crustal components. Another facet of USGS research addresses disturbance to

crusts. Cyanobacterial fibers are no

match for the compressional stress of

livestock hooves, off-road vehicle

tires, or heavy foot traffic. Recovery

of these crusts from such impacts in

arid areas can take up to 250 years.

Such disturbance may alter the role

these organisms play in an ecosystem

by influencing how they respond to

their physical environment. For this

reason, it also is important to understand the relation between environmental factors and crustal components in disturbed environments.

With this information, land managers

may be able to predict the consequences of different types and

intensities of land use under different

climatic regimes. USGS research also

is directed at developing restoration

techniques for ecosystems in which

crusts have been destroyed or damaged.

Washington County Habitat

Conservation Plan

To conserve biodiversity while

allowing for economic growth in

southwestern Utah, the Washington

County Board of Commissioners

began a Habitat Conservation Plan in

1996. USGS scientists are providing

biological expertise and are working

with the Utah Division of Wildlife

Resources, the U.S. Bureau of Land

Management (BLM), and Washington

County. Providing adequate knowledge of the habitat for a viable

population of the desert tortoise (fig.

6), a federally listed threatened

species, is an objective of the plan.

USGS researchers collect biological

information on diet, nutrition, home

range, habitat use, and distribution of

the desert tortoise in Washington

County in a long-term research

project on the ecology of this species.

This information has been used for

designing and establishing a 60,000-

acre desert reserve adjacent to the

municipalities of St. George, Washington City, and Ivins. The USGS is

developing a plan to monitor and

analyze the distributions of plants

and animals for regional management

of multiple species.

Single Edition Program

The Single Edition Program is a

mapping agreement with the U.S.

Forest Service to revise, maintain,

and distribute 1:24,000-scale topographic (7.5-minute quadrangle)

maps of U.S. National Forest lands.

About 500 maps cover the 7 National

Forests in Utah, which comprise

more than 8 million acres. The U.S.

Forest Service maintains the maps,

and the USGS prints and distributes

them. The U.S. Forest Service

Geospatial Service and Technology

Center in Salt Lake City coordinates

this program. Single edition maps, as

well as standard USGS products, are

available from map dealers, USGS

Earth Science Information Centers,

and National Forest Visitor Centers,

or by ordering through the Internet.

Figure 6. A desert tortoise in the

Red Cliffs Desert Reserve, north of

St. George.