Areas Susceptible to Irrigation-Induced

Selenium Contamination of Water and

Biota in the Western United States

U.S. GEOLOGICAL SURVEY CIRCULAR 1180

Marine rocks like those exposed at the base of Mount Garfield, Colo., are sources for trace elements in many irrigated

areas of the Western United States. Photograph by James G. Crock, U.S. Geological Survey, 1992

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U.S. GEOLOGICAL SURVEY CIRCULAR

Areas Susceptible to Irrigation-Induced

Selenium Contamination of Water and

Biota in the Western United States

1180

By RALPH L. SEILER, JOSEPH P. SKORUPA, and LORRI A. PELTZ

Prepared in cooperation:

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Carson City, Nevada

1999
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

U.S. GOVERNMENT PRINTING OFFICE :

Free on application to the

U.S. Geological Survey

Information Services

Box 25286 Federal Center

Denver, CO 80225

U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Library of Congress Cataloging-in-Publication Data

Seiler, R. L., 1948–

Areas susceptible to irrigation-induced selenium contamination of water and

biota in the western United States / by Ralph L. Seiler, Joseph P. Skorupa,

and Lorri A. Peltz.

p. cm. — (U.S. Geological Survey circular ; 1180)

Includes bibliographical references.

ISBN 0–607–92082–3

1. Selenium—Environmental aspects—West (U.S.) 2. Irrigation—

Environmental aspects—West (U.S.) 3. Geographic information systems—

West (U.S.) I. Skorupa, Joseph P., 1954– . II. Peltz, Lorri A. (Lorri Ann),

1959– . III. Title. IV. Series.

QH545.S45S44 1999 99–29012

577.27’5724’0978—dc21

1999
Contents III

CONTENTS

Abstract 1

Introduction 1

Background 1

Purpose and scope 2

Acknowledgments 2

Sources of selenium 2

Study methods 5

Physical classification of areas 7

Geology 7

Climate 7

Hydrology 11

Classification of study areas by selenium concentrations 12

Water 12

Biota 12

Use of geographic information system to create maps 14

Geologic data layers 14

Climatologic data layers 15

Land-use data layers 16

Factors affecting selenium concentrations in water 16

Geology 16

Climate 18

Hydrology 18

Deformities in aquatic birds and selenium concentrations in bird eggs 20

Map identifying areas susceptible to selenium contamination 21

Assessing map reliability 21

Test areas 21

Correctness of analysis 25

Accuracy and precision of maps 27

Land use within susceptible areas 28

Discussion and summary 28

References cited 32

FIGURES

1. Map of Western United States showing study areas and data-collection sites

included in National Irrigation Water Quality Program 3

2. Map of Western United States showing areas where potentially seleniferous

rocks form bedrock 6

3. Photograph showing Likes Lake, a shallow water body and wetland in an

arid terminal basin northeast of Fallon, Nev. 11

4. Graph showing statistical summary of selenium concentrations in filtered

surface water from 26 National Irrigation Water Quality Program study

areas 13

5. Graph showing relations among selenium concentration, aridity, and

geology for 26 National Irrigation Water Quality Program study areas 17

6. Map of Western United States showing areas where evaporation index is

greater than 2.5 19
IV Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

FIGURES

7. Photograph of redhead duck embryos from middle Green River Basin study

area in Utah, showing twisted bill and other deformities typical of those

caused by selenium 20

8–12. Maps of Western United States showing:

8. Areas that are susceptible to irrigation-induced selenium

contamination 22

9. National Irrigation Water Quality Program study areas, test areas,

and areas that are susceptible to irrigation-induced selenium

contamination 24

10. Bureau of Reclamation project areas in relation to areas that are

susceptible to irrigation-induced selenium contamination 29

11. National Wildlife Refuges in relation to areas that are susceptible to

irrigation-induced selenium contamination 30

12. Irrigated agricultural land in relation to areas that are susceptible to

irrigation-induced selenium contamination 31

TABLES

1. Reconnaissance and detailed studies concerning National Irrigation

Water Quality Program study areas 4

2. Characteristics of National Irrigation Water Quality Program study

areas 8

3. Generalized geology of National Irrigation Water Quality Program study

areas 10

4. Geographic-information-system data layers used to create maps in this

report 15

5. Western United States land areas where evaporation indexes exceed four

threshold values 20

6. Western United States land areas where evaporation indexes exceed four

threshold values and where bedrock consists of Upper Cretaceous or

Tertiary marine sedimentary rocks 21

7. Reliability of map assessment of study-area susceptibility and interpolation of climatic variables 26

CONVERSION FACTORS AND ABBREVIATED WATER-QUALITY UNITS

Multiply By To obtain

acre 4,047 square meter

foot 0.3048 meter

inch 25.4 millimeter

mile 1.609 kilometer

square mile 2.59 square kilometer

Abbreviated water-quality units used in this report:

μg/L, microgram per liter

μg/g, microgram per gram

mg/kg, milligram per kilogram
INTRODUCTION 1

Abstract

The U.S. Department of the Interior (DOI) studied contamination induced by irrigation drainage in 26 areas of the

Western United States during 1986–95. Comprehensive

compilation, synthesis, and evaluation of the data resulting

from these studies were initiated by DOI in 1992. Soils and

ground water in irrigated areas of the West can contain high

concentrations of selenium because of (1) residual selenium

from the soil’s parent rock beneath irrigated land; (2) selenium derived from rocks in mountains upland from irrigated

land by erosion and transport along local drainages, and

(3) selenium brought into the area in surface water imported

for irrigation. Application of irrigation water to seleniferous

soils can dissolve and mobilize selenium and create hydraulic gradients that cause the discharge of seleniferous ground

water into irrigation drains. Given a source of selenium, the

magnitude of selenium contamination in drainage-affected

aquatic ecosystems is strongly related to the aridity of the

area and the presence of terminal lakes and ponds. Marine

sedimentary rocks and deposits of Late Cretaceous or Tertiary age are generally seleniferous in the Western United

States. Depending on their origin and history, some Tertiary

continental sedimentary deposits also are seleniferous. Irrigation of areas associated with these rocks and deposits can

result in concentrations of selenium in water that exceed criteria for the protection of freshwater aquatic life.

Geologic and climatic data for the Western United States

were evaluated and incorporated into a geographic information system (GIS) to produce a map identifying areas susceptible to irrigation-induced selenium contamination. Land is

considered susceptible where a geologic source of selenium

is in or near the area and where the evaporation rate is more

than 2.5 times the precipitation rate. In the Western United

States, about 160,000 square miles of land, which includes

about 4,100 square miles (2.6 million acres) of land irrigated

for agriculture, has been identified as being susceptible. Biological data were used to evaluate the reliability of the map.

In 12 of DOI’s 26 study areas, concentrations of selenium

measured in bird eggs were elevated sufficiently to significantly reduce hatchability of the eggs. The GIS map identifies

9 of those 12 areas. Deformed bird embryos having classic

symptoms of selenium toxicosis were found in four of the

study areas, and the map identifies all four as susceptible to

irrigation-induced selenium contamination.

INTRODUCTION

Background

In 1983, incidents of mortality, congenital deformities,

and reproductive failures in aquatic birds were discovered at

Kesterson Reservoir, a U.S. Department of the Interior

(DOI) National Wildlife Refuge in western San Joaquin Valley, Calif. The cause of these adverse biological effects was

determined to be poisoning by selenium carried by irrigation

drainage into areas used by wildlife (Ohlendorf and others,

1986, 1988). The U.S. Congress and environmental groups

wanted to know if what happened at Kesterson Reservoir

was an anomaly or if similar effects from irrigation drain

water might occur elsewhere in the Nation. Therefore, in

1985, DOI implemented the National Irrigation Water Quality Program (NIWQP) to study the effects of irrigation drainage on water resources and on fish and wildlife (Deason,

1986).

Areas Susceptible to Irrigation-Induced

Selenium Contamination of Water and

Biota in the Western United States

By RALPH L. SEILER, U.S. Geological Survey; JOSEPH P. SKORUPA, U.S. Fish and Wildlife

Service; and LORRI A. PELTZ, Nature Conservancy, formerly of U.S. Geological Survey

Introduction
2 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

The DOI has constructed or manages more than 600 irrigation or irrigation-drainage facilities and National Wildlife

Refuges in the 17 conterminous Western States. During

1985–86, the NIWQP screened existing data from these DOI

facilities. As a result, 26 areas (A through Z in fig. 1 and table

1) were selected for on-site reconnaissance investigations.

After reconnaissance investigations confirmed that irrigation

drainage had caused significant harmful effects on human

health and on fish and wildlife, or otherwise had impaired

beneficial uses of the water, detailed investigations were

done in 9 of these 26 areas to determine the extent, magnitude, effects, and causes of contamination. NIWQP did the

detailed investigations in eight of the nine areas (F, H, I, N, U,

V, W, and X), and the remaining area (Y) was studied under a

separate Federal–State cooperative program (Moore and

others, 1990).

U.S. Geological Survey publications describing results

of investigations of the individual NIWQP study areas are

listed in table 1. Some previous investigators (Sylvester and

others, 1988; Feltz and others, 1991; Engberg and Sylvester,

1993; Presser and others, 1994; Seiler, 1995) evaluated data

for some or all NIWQP study areas and observed that several

factors determine the concentration of trace-element contaminants associated with irrigation drainage. Some of the

more important factors are

• Pervasive geologic source of pertinent

trace elements

• Arid to semiarid climate

• Topographically closed basin or sink.

Presser (1994b, p. 447) summarized 11 biogeochemical processes involved in the transport of selenium from rock to

waterfowl at Kesterson Reservoir. Many of these processes

probably occur in the areas that NIWQP found to be contaminated with selenium.

In 1992, NIWQP began a multiyear project to compile

and evaluate information collected during completed as well

as ongoing NIWQP investigations. The overall objective of

the data synthesis is to identify physical factors and biogeochemical processes associated with irrigation-induced

contamination of water and biota in the Western United

States. Because selenium is the contaminant that most frequently exceeds water-quality criteria (Seiler, 1996), a secondary objective of the data synthesis has been to develop

the ability to predict where irrigation-induced selenium contamination of water and biota is most likely.

Purpose and Scope

This report presents an analysis of data collected at the

26 areas in the Western United States that were investigated

by the NIWQP from 1986 through 1995. Synthesis of these

data resulted in a map that identifies areas in the Western

United States which are susceptible to irrigation-induced

selenium contamination. The map is intended to be used as a

screening and ranking tool by managers. After ranking the

likelihood of contamination in several areas, resources can

be directed toward assessing selenium contamination in

areas where it is most likely to occur. The reliability of the

map is assessed by using biological and water-quality data

collected for programs other than NIWQP.

Acknowledgments

George H. Taylor, Oregon State Climatologist, provided

a preliminary data layer of precipitation in the United States

based on a proprietary regression model. A. Dennis Lemly,

U.S. Forest Service, and David L. Butler, U.S. Geological

Survey (USGS), provided critical reviews that greatly

improved the manuscript. Special thanks are due Theresa S.

Presser and David Z. Piper, USGS, for sharing their thoughts

on geological sources of selenium and the mechanisms by

which rocks and soils become seleniferous. The authors

thank the members of the U.S. Fish and Wildlife Service,

Bureau of Reclamation, Bureau of Indian Affairs, and USGS

who participated in the NIWQP investigations and provided

detailed information about the study areas.

SOURCES OF SELENIUM

The sources and distribution of selenium-bearing soils

in the Western United States were intensively researched

during the 1930’s and 1940’s after the discovery that selenium in pasturage was the cause of a fatal disease afflicting

cattle and horses. During 1968–75 the Bureau of Reclamation built the upper 85-mile reach of the San Luis Drain,

which terminated at Kesterson Reservoir in the San Joaquin

Valley in California (Tanji and others, 1986). By the 1960’s,

when the decisions were made to construct the drain and to

use Kesterson Reservoir as its terminus, the awareness of

selenium as a toxicant had faded. Early water-quality concerns focused instead on salinity, boron, nitrate, and pesticides (Tanji and others, 1986). The collapse of the warmwater fishery and the finding of deformed birds at Kesterson

Reservoir in 1983 led to the rediscovery of selenium as an

important environmental toxicant. Since then, intensive

investigations have been made in the San Joaquin Valley and

elsewhere to understand the sources of selenium.
SOURCES OF SELENIUM 3

Figure 1. Study areas and data-collection sites included in National Irrigation Water Quality Program.

120°

45°

40°

35°

30°

115° 110° 105° 100°

95°

EXPLANATION

Data-collection site for National Irrigation Water Quality 

 Program study area—Letter is area identifier (table 2)

T

0 250 500 MILES

0 250 500 KILOMETERS

State boundaries from TIGER/Line digital data, 1:100,000, 1992; 

coastlines and hydrology from U.S. Geological Survey digital data, 

1:2,000,000, 1970

Albers Equal-Area Conic projection

Standard parallels 29°30' and 45°30', central meridian 96°00' 

X

A

B

C

D

E

F

G

H

J

K

L

M

N

O

Q

R

S

T

U

V

W

Y

Z

P

I

WASHINGTON

OREGON

CALIFORNIA

NEVADA

ARIZONA

UTAH

IDAHO

MONTANA

WYOMING

COLORADO

NEW

MEXICO

TEXAS

OKLAHOMA

KANSAS

NEBRASKA

SOUTH

DAKOTA

NORTH

DAKOTA

GULF

O F

MEXICO

P

A

C I F I C

O

C

E

A

N

MEXICO

CANADA

Sources of Selenium
4 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

TABLE 1. Reconnaissance and detailed studies concerning National Irrigation Water Quality Program study areas

[Area identifier: See table 2 and figure 1. —, none]

Area

identifier Study area

References

Reconnaissance studies Detailed studies

A American Falls Reservoir, Idaho Low and Mullins, 1990 —

B Angostura Reclamation Unit, South Dakota Greene and others, 1990 —

C Belle Fourche Reclamation Project, South Dakota Roddy and others, 1991 —

D Columbia River Basin, Washington Embry and Block, 1995 —

E Dolores–Ute Mountain area, Colorado Butler and others, 1995 —

F Gunnison River Basin–Grand Valley Project, Colorado Butler and others, 1991 Butler and others, 1994, 1996

G Humboldt River area, Nevada Seiler and others, 1993 —

H Kendrick Reclamation Project, Wyoming Peterson and others, 1988 See, Naftz, and others, 1992; See,

Peterson, and Ramirez, 1992.

I Klamath Basin Refuge Complex, California–Oregon Sorenson and Schwarzbach, 1991 MacCoy, 1994; Dileanis and

others, 1996

J Lower Colorado River valley, California–Arizona Radtke and others, 1988 —

K Lower Rio Grande valley, Texas Wells and others, 1988 —

L Malheur National Wildlife Refuge, Oregon Rinella and Schuler, 1992 —

M Middle Arkansas River Basin, Colorado–Kansas Mueller and others, 1991 —

N Middle Green River Basin, Utah Stephens and others, 1988 Peltz and Waddell, 1991; Stephens

and others, 1992

O Middle Rio Grande, New Mexico Ong and others, 1992 —

P Milk River Basin, Montana Lambing and others, 1988 —

Q Owyhee–Vale Reclamation Project areas, Oregon–Idaho Rinella and others, 1994 —

R Pine River area, Colorado Butler and others, 1993 —

S Riverton Reclamation Project, Wyoming Peterson and others, 1991 —

T Sacramento Refuge Complex, California Dileanis and others, 1992 —

U Salton Sea area, California Setmire and others, 1990 Schroeder and others, 1993;

Setmire and others, 1993

V San Juan River area, New Mexico Blanchard and others, 1993 Thomas and others, 1997

W Stillwater Wildlife Management Area, Nevada Hoffman and others, 1990 Rowe and others, 1991; Lico,

1992; Hallock and Hallock,

1993; Hoffman, 1994.

X Sun River area, Montana Knapton and others, 1988 Lambing and others, 1994;

Nimick and others, 1996

Y Tulare Lake Bed area, California Schroeder and others, 1988 Moore and others, 1990

Z Vermejo Project area, New Mexico Bartolino and others, 1996 —
STUDY METHODS 5

Tidball and others (1991) noted that in the Diablo

Range, along the west side of the San Joaquin Valley, Upper

Cretaceous to Oligocene marine sedimentary rocks are variously seleniferous, whereas Pliocene and younger nonmarine sedimentary rocks generally are nonseleniferous. The

importance of Cretaceous sedimentary rocks as sources of

selenium in the Western United States has been known since

the 1930’s. Lakin and Byers (1941) summarized some of the

research done during the 1930’s and 1940’s and concluded

that “all areas of soils derived from material of Cretaceous

age are then open to suspicion of the presence of harmful

quantities of selenium * * *.” The regional importance of

Upper Cretaceous marine sedimentary rocks as sources of

selenium is indicated by their large areal extent; they form

the bedrock beneath about 311,000 square miles of land in

the 17 conterminous Western States (fig. 2).

Understanding general mechanisms of selenium distribution and enrichment in rocks of different types is important to identifying source areas. The selenium in marine

sedimentary rocks may have been derived by direct deposition of particulate matter either from erosion of seleniferous

deposits on the continental landmass or from fallout of

seleniferous dusts and particles from the atmosphere. Several authors have proposed that oceans during Cretaceous

time were enriched in selenium from volcanic activity

(Byers and others, 1936; Berrow and Ure, 1989). Violent

volcanic activity during Late Cretaceous time, when the

Rocky Mountains began to rise, released selenium that was

deposited in a large inland sea in what is now the Western

United States (Trelease and Beath, 1949).

However, physical processes of selenium accumulation

in marine sediments during Cretaceous time may have been

of minor importance compared to biological processes.

Presser (1994b) suggested that the bioaccumulation of selenium in the oceans and later deposition were primary mechanisms of selenium enrichment during the Cretaceous.

Because bioaccumulation and deposition of seleniferous

organic matter can occur even if selenium concentrations in

oceans are not enriched by volcanic activity, any deposit laid

down in a shallow, productive marine environment may be

seleniferous.

Generally, Tertiary marine sedimentary deposits also

are seleniferous. They contain selenium derived by bioaccumulation and particulate matter derived by the erosion of

older (Cretaceous) seleniferous sedimentary deposits. Tertiary marine sedimentary deposits form the bedrock beneath

almost 84,800 square miles of land in the Western United

States (fig. 2). Presser (1994a) identified seleniferous marine

formations of Upper Cretaceous–Paleocene, Eocene–Oligocene, and Miocene ages in the coast ranges of California.

Tertiary continental deposits derived from eroded

Upper Cretaceous marine sedimentary rocks also may be

seleniferous. Trelease and Beath (1949) identified several

seleniferous formations of Tertiary age in Utah and Wyoming. However, they noted that sedimentary deposits of Tertiary age differ greatly in selenium content because of the

diverse conditions that control deposition. Tertiary continental deposits form the bedrock beneath about 366,000 square

miles of land in the Western United States (fig. 2).

Irrigation of seleniferous soils can dissolve and mobilize selenium and transport it in ground water into irrigation

drains. Because drainage from agricultural areas is a major

source of selenium in wildlife areas, the processes by which

selenium is contributed to soils and ground water need to be

understood. In most of the selenium-contaminated areas

investigated by NIWQP, soils contain residual selenium

from weathering of the parent rock. In the San Joaquin Valley, soils contain selenium that was brought in from seleniferous deposits in the surrounding mountains (Presser,

1994a,b). Thus, maps of bedrock geology can be used to

identify areas having potentially seleniferous soils and

ground water.

Soils and ground water in an area also can become

seleniferous by surface-water transport of selenium from

sources hundreds of miles upstream. For example, fish mortality in Martin Lake in east Texas (King and others, 1994)

and Belews Lake in North Carolina (Lemly, 1985) has been

attributed to selenium brought in from an industrial source;

both reservoirs received seleniferous ash from nearby coalfired power plants. Also, the Colorado River transports both

agriculturally and naturally derived selenium into the Imperial Valley in California, where the water is used for irrigation.

STUDY METHODS

The 26 study areas (fig. 1) were characterized by gathering geologic, hydrologic, climatologic, biologic, and

chemical data in a relational database (Seiler, 1996). The

data were analyzed to identify factors common to seleniumcontaminated areas, and a geographic information system

(GIS) was used to map the spatial distribution of some of

those factors. Biologic, geologic, climatologic, and hydrologic data, including information about water quality, are

summarized in table 2.

Study Methods
6 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

Figure 2. Areas in Western United States where potentially seleniferous rocks form bedrock. Geology

from King and Beikman (1974a). For base credit, see figure 1.

120°

45°

40°

35°

30°

115° 110° 105° 100°

95°

EXPLANATION

Tertiary marine sedimentary deposits

Tertiary continental sedimentary deposits

Upper Cretaceous marine sedimentary rocks

0 250 500 MILES

0 250 500 KILOMETERS
STUDY METHODS 7

Physical Classification of Areas

Geology

Because the principal source of selenium in irrigated

soils is residual selenium derived from the soil’s parent

material, knowledge of the geologic units underlying and

surrounding irrigated land is very important. The King and

Beikman (1974a) 1:2,500,000-scale geologic map of the

United States was used as the source of geologic information

about the 26 study areas. King and Beikman (1974b) noted

that their national-scale geologic map would be used in planning activities in conjunction with other national maps showing environmental features such as climate and land use. For

this report, using a small-scale geologic map for screening

and ranking purposes is appropriate, although larger scale,

more detailed geologic maps are available for individual

study areas.

King and Beikman’s (1974a) geologic-map units are

listed for each study area in table 3; the units are ranked by

the number of individual data-collection sites that are within

a particular geologic unit in each study area. The most common geologic units in the study areas are Cretaceous to Quaternary marine or continental sedimentary deposits.

Potentially seleniferous geologic units were grouped

into three main categories for this report. King and Beikman’s (1974a) Upper Cretaceous stratified sedimentary

sequences that were deposited mainly in marine environments are hereafter referred to as Upper Cretaceous marine

sedimentary rocks or deposits; Paleocene to Pliocene,

mainly marine, stratified sedimentary sequences are hereafter referred to as Tertiary marine sedimentary deposits; and

Paleocene to Pliocene continental sedimentary deposits are

hereafter referred to as Tertiary continental sedimentary

deposits.

The 26 study areas were classified into groups primarily

on the basis of their association or lack of association with

Upper Cretaceous marine sedimentary rocks (table 2):

• Areas where most of the bedrock beneath

irrigated lands consists of Upper Cretaceous marine sedimentary rocks

• Areas where the bedrock beneath irrigated

lands is a combination of Upper Cretaceous marine sedimentary rocks and

Tertiary continental sedimentary rocks

• Areas where the bedrock in mountains upland from irrigated lands includes Upper

Cretaceous marine sedimentary rocks or

includes both Upper Cretaceous and Tertiary marine sedimentary rocks

• Areas where rivers upstream from irrigated

lands traverse Upper Cretaceous marine

sedimentary rocks or both Upper Cretaceous and Tertiary marine sedimentary

rocks

• Areas that are not associated with Upper

Cretaceous marine sedimentary rocks.

The focus on Upper Cretaceous marine sedimentary rocks is

because these rocks are known to be generally seleniferous

and because they are common in the NIWQP study areas.

NIWQP study areas containing Tertiary continental sedimentary deposits were not classified separately because in

most instances they also are associated with Upper Cretaceous marine sedimentary rocks.

Climate

The amount of precipitation and the amount of water

lost through evaporation are important factors in determining whether an area is susceptible to selenium contamination. The data on mean annual precipitation used in this

report are from the reports that describe results of individual

studies of the 26 areas (table 2). Where precipitation data for

an area were reported as a range of values, the midpoint of

the range was chosen to represent the precipitation in the

area.

The evaporation rate used to characterize each of the 26

areas is the free-water-surface evaporation (FWSE) rate. The

FWSE rate was chosen instead of the pan-evaporation rate

because of the availability of a national map of FWSE rates,

which ensures that a consistent method of quantifying the

evaporation rates was applied to the 26 study areas. FWSE

rates for the 26 areas were determined from evaporation

maps of the United States prepared by Farnsworth and others

(1982).

Precipitation and evaporation data were generalized

into a single value to characterize the aridity of each of the

26 study areas and their potential for evaporative concentration of drain water. This value, herein called the evaporation

index (EI), is the ratio of annual FWSE to mean annual precipitation. EI values for the 26 areas are listed in table 2.

Physical Classification of Areas
8 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

TABLE 2. Characteristics of National Irrigation Water Quality Program study areas

[C, contaminated; S, seleniferous; UC, uncontaminated; —, not sampled or not applicable; <, less than]

Area

identifier1 Study area

Characteristics related to selenium contamination

Selenium content of

surface water5

(micrograms per liter)

c

Evaporation

index2

Selenium in

source water3

(micrograms

per liter)

Geology4 75th percentile6 Range 

A American Falls Reservoir, Idaho 3.7 — Irrigated lands are not associated with uK marine

sedimentary rocks.

1 <1 – 6 

B Angostura Reclamation Unit, South

Dakota.

2.8 2 Most of bedrock beneath irrigated lands consists of

uK marine sedimentary rocks.

5 <1 – 6 

C Belle Fourche Reclamation

Project, South Dakota.

2.8 3 Most of bedrock beneath irrigated lands consists of

uK marine sedimentary rocks.

5 2 – 11 

D Columbia River Basin, Washington 5.0 <1 Irrigated lands are not associated with uK marine

sedimentary rocks.

<1 <1 – 4 

E Dolores–Ute Mountain area,

Colorado.

4.4 <1 Most of bedrock beneath irrigated lands consists of

uK marine sedimentary rocks.

7 <1 – 88 

F Gunnison River Basin–Grand

Valley Project, Colorado.

5.4 9 Most of bedrock beneath irrigated lands consists of

uK marine sedimentary rocks.

35 <1 – 380 

G Humboldt River area, Nevada 8.1 1 Irrigated lands are not associated with uK marine

sedimentary rocks.

2 <1 – 4 

H Kendrick Reclamation Project,

Wyoming.

3.7 2 Most of bedrock beneath irrigated lands consists of

uK marine sedimentary rocks.

64 <1 – 5,300 

I Klamath Basin Refuge Complex,

California–Oregon.

3.0 <1 Irrigated lands are not associated with uK marine

sedimentary rocks.

<1 <1 – <1 

J Lower Colorado River valley,

California–Arizona.

18.9 2 Rivers traverse uK marine sedimentary rocks

upstream from irrigated lands.

2 <1 – 2 

K Lower Rio Grande valley, Texas 2.2 1 Rivers traverse uK and

T marine sedimentary rocks

upstream from irrigated lands.

1 <1 – 2 

L Malheur National Wildlife Refuge,

Oregon.

4.3 <1 Irrigated lands are not associated with uK marine

sedimentary rocks.

<1 <1 – <1 

M Middle Arkansas River Basin,

Colorado–Kansas.

4.0 5 Most of bedrock beneath irrigated lands consists of

uK marine and

T continental sedimentary rocks.

10 2 – 52 

N Middle Green River Basin, Utah 5.7 — Bedrock beneath irrigated lands consists of uK

marine and

T continental sedimentary rocks.

73 <1 – 8,300 
STUDY METHODS 9

1 Used in figure 1.2 Mean annual free-water-surface evaporation for area divided by mean annual precipitation.3 Maximum selenium concentration measured in surface-water body identified as providing water used for irrigation.4 Bedrock geology after King and Beikman (1974a). T, Tertiary; uK, Upper Cretaceous.5 Filtered surface water in and downstream from irrigated areas.6 Rounded to nearest microgram per liter.7 Criteria used: uncontaminated (UC), 75th percentile of selenium concentrations in surface water is less than 3 micrograms per liter; seleniferous (S), 75th percentile is at least 3 but less than 5 m

is at least 5 micrograms per liter. Avian effect level (Skorupa and Ohlendorf, 1991) is 3 micrograms per liter; chronic criterion for protection of freshwater aquatic life (U.S. Environmental Protection A

8 Normal, less than or equal to 3 micrograms per gram; elevated, greater than 3 micrograms per gram but less than 8 micrograms per gram; embryotoxic, equal to or greater than 8 micrograms 9 William G. Kepner, U.S. Fish and Wildlife Service (written commun., 1989).

10 Calculated by using precipitation during year of data collection rather than mean annual precipitation because all data were collected in June and August 1986. (See section titled “Climate” u

O Middle Rio Grande, New Mexico 6.8 <1 Irrigated lands are not associated with uK marine

sedimentary rocks.

<1 <1 – 1 

P Milk River Basin, Montana 101.9 <1 Most of bedrock beneath irrigated lands consists of

uK marine sedimentary rocks.

<1 <1 – <1 

Q Owyhee–Vale Reclamation Project

areas, Oregon–Idaho.

4.5 <1 Irrigated lands are not associated with uK marine

sedimentary rocks.

2 <1 – 5 

R Pine River area, Colorado 3.5 <1 Bedrock beneath irrigated lands consists of uK

marine and T continental sedimentary rocks.

6 <1 – 94 

S Riverton Reclamation Project,

Wyoming.

4.9 <1 Most of bedrock beneath irrigated lands consists

of T continental sedimentary rocks; bedrock in

mountains upland from irrigated lands includesuK marine sedimentary rocks.

5 <1 – 12 

T Sacramento Refuge Complex,

California.

2.6 <1 Bedrock in mountains upland from irrigated lands

includes uK marine sedimentary rocks.

<1 <1 – 5 

U Salton Sea area, California 24.5 3 Rivers traverse uK marine sedimentary rocks

upstream from irrigated lands.

8 <1 – 10 

V San Juan River area, New Mexico 7.4 <1 Bedrock beneath irrigated lands consists of uK

marine and T continental sedimentary rocks.

3 <1 – 67 

W Stillwater Wildlife Management

Area, Nevada.

10.0 <1 Irrigated lands are not associated with uK marine

sedimentary rocks.

<1 <1 – 21 

X Sun River area, Montana 3.0 <1 Most of bedrock beneath irrigated lands consists of

uK marine sedimentary rocks.

8 <1 – 190 

Y Tulare Lake Bed area, California 11.1 — Bedrock in mountains upland from irrigated lands

includes uK and T marine sedimentary rocks.

265 <1 – 390 

Z Vermejo Project area, New Mexico 3.9 1 Most of bedrock beneath irrigated lands consists of

uK marine sedimentary rocks.

6 <1 – 23 

Physical Classification of Areas
10 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

1 Used in figure 1; also, see table 2.

TABLE 3. Generalized geology of National Irrigation Water Quality Program study areas

[Geologic units within each study area are ranked according to relative number of individual data-collection sites (fig. 1) having the indicated

geology. Geologic symbols and descriptions used are adapted from the compilation by King and Beikman (1974a). Generally in decreasingage order, these geologic units include Early Proterozoic igneous and metamorphic rocks (Xg, granitic rocks; Xm, orthogneiss and paragneiss); upper Paleozoic stratified, mainly marine, sedimentary rocks (uPz); Upper Cretaceous stratified, mainly marine, sedimentary rocks

(uK1, the Woodbine and Tuscaloosa Groups, locally including some Lower Cretaceous rocks not mapped separately; uK2, the Austin and Eagle

Ford Groups; uK3, the Taylor Group; and uK4, the Navarro Group); Paleocene continental sedimentary deposits (Txc); Eocene continental

sedimentary deposits (Tec); the Eocene Jackson Group (Te3); Miocene volcanic rocks (Tmf, felsic; Tmv, nonfelsic); Pliocene continental

sedimentary deposits (Tpc); Pliocene nonfelsic volcanic rocks (Tpv); thick and widespread Quaternary stratified sedimentary sequences (Q);

Quaternary nonfelsic volcanic rocks (Qv); and Holocene stratified sedimentary deposits, Great Plains only (Qh). Geologic units exclude

Pleistocene glacial deposits that blanket large parts of the northern interior States and are not shown on King and Beikman’s (1974a) map]

Area

identifier1 Study area

Ranked geologic units

1234

A American Falls Reservoir, Idaho Q

B Angostura Reclamation Unit, South Dakota uK3 uK2 uK1

C Belle Fourche Reclamation Project, South Dakota uK2 uK3

D Columbia River Basin, Washington Q Tmv

E Dolores–Ute Mountain area, Colorado uK1 uK2

F Gunnison River Basin–Grand Valley Project, Colorado uK2 uK1

G Humboldt River area, Nevada Q

H Kendrick Reclamation Project, Wyoming uK2

I Klamath Basin Refuge Complex, California–Oregon Q Tpv

J Lower Colorado River valley, California–Arizona Q Xm Xg uPz

K Lower Rio Grande valley, Texas Qh Te3

L Malheur National Wildlife Refuge, Oregon Q Tmv Tmf

M Middle Arkansas River Basin, Colorado–Kansas uK2 uK3 Q Tpc

N Middle Green River Basin, Utah:

Ouray and Pariette subareas Tec

Stewart subarea uK2 uK3

O Middle Rio Grande, New Mexico Tpc

P Milk River Basin, Montana uK3

Q Owyhee–Vale Reclamation Project areas, Oregon–Idaho Q Tmv Tpc

R Pine River area, Colorado Tec uK4 uK3

S Riverton Reclamation Project, Wyoming Tec

T Sacramento Refuge Complex, California Q

U Salton Sea area, California Qv

V San Juan River area, New Mexico uK2 uK4 Txc

W Stillwater Wildlife Management Area, Nevada Q

X Sun River area, Montana uK2 uK3

Y Tulare Lake Bed area, California Q

Z Vermejo Project area, New Mexico uK3
STUDY METHODS 11

In two of the areas, Milk River Basin in Montana and

Riverton Reclamation Project area in Wyoming (areas P and

S, table 2), all data were collected during a short period in a

climatically unusual year. In the Milk River Basin, precipitation during the year of data collection was almost twice the

normal amount. During the spring and early summer, prior to

data collection during June and August, much more water

than normal was delivered to the area, and therefore contaminants became diluted (Lambing and others, 1988). Precipitation during the year of data collection rather than the mean

annual precipitation was used to calculate EI. In the Riverton

Reclamation Project area, precipitation was less than half the

normal amount, and temperatures (and evaporation) were

above normal (Peterson and others, 1991). However,

because of available water in storage, greater than normal

irrigation-water deliveries were made to the area during the

period of data collection (August and November 1986) to

help offset the greater than normal evaporative losses. EI

was calculated on the basis of the mean annual precipitation.

Hydrology

In terminal lakes (lakes without natural outlets; fig. 3),

evaporation can result in very high concentrations of selenium because the solutes are retained and accumulated rather

than flushed out. Areas were classified hydrologically as

open basin or closed basin depending on whether they contain lakes or ponds that receive irrigation drain water and that

are terminal during nonflood years (Seiler, 1995). Although

these water bodies range from very large (the Salton Sea) to

very small (unnamed stockponds or impoundments), size

was not considered in the hydrologic classification.

Under certain circumstances, selenium contamination

can occur in an area that has no local geologic sources of

selenium because selenium is brought into the area from

elsewhere. Maximum selenium concentrations observed in

samples from water bodies identified as being sources of irrigation water exceeded or equaled 1 μg/L in 10 of the study

areas (table 2). In 4 of the 10 areas, no local geologic sources

Figure 3. Likes Lake, a shallow water body and wetland in an arid terminal basin in the Stillwater Wildlife Management

Area in Nevada. Such wetlands provide important feeding and nesting areas for migratory birds but commonly contain

high salt and trace-element concentrations. Photograph by Ralph L. Seiler, U.S. Geological Survey, 1994.

Physical Classification of Areas
12 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

of selenium exist. In three of those four areas, the rivers supplying water for irrigation traverse Upper Cretaceous or Tertiary marine sedimentary deposits upstream from irrigated

areas. Selenium is brought into the Salton Sea area and lower

Colorado River valley in California and Arizona (U and J,

table 2) in Colorado River water, which traverses Upper Cretaceous marine sedimentary rocks and receives drain water

from irrigated agricultural lands hundreds of miles upstream.

Selenium is brought also into the lower Rio Grande valley in

Texas (K, table 2) in Rio Grande water, which traverses

Upper Cretaceous and Tertiary marine sedimentary deposits

many miles upstream. Although selenium is brought into the

Humboldt River area in Nevada (G, table 2), the Humboldt

River Basin contains no Upper Cretaceous and Tertiary

marine sedimentary deposits.

Classification of Study Areas by Selenium

Concentrations

Water

Water-quality criteria used in this study were based on

the U.S. Environmental Protection Agency’s (1987) chronic

criterion for selenium for the protection of freshwater

aquatic life, 5 μg/L, and on the avian effect level (Skorupa

and Ohlendorf, 1991), 3 μg/L total recoverable selenium.

Skorupa and Ohlendorf (1991) found that, under some environmental conditions, a range of 3 to 20 μg/L total recoverable selenium is hazardous to some species of aquatic birds.

The NIWQP investigations typically measured filtered selenium, not total recoverable selenium, in water samples.

Seiler (1996) presented evidence that in NIWQP samples,

filtered- and total-selenium concentrations are nearly the

same over a wide range of concentrations; however, whether

the analyses are interchangeable is still a matter of debate.

To summarize selenium data, only filtered-selenium

concentrations in water from surface-water sites in and

downstream from irrigated land were used. Selenium concentrations in ground water, in surface water used for irrigation, and in sediment were not used for this analysis. For

simplicity, data for flowing and impounded bodies of water

were combined, because no samples or very few samples

were collected from lakes and ponds in some areas. Statistics

summarizing filtered-selenium concentrations in surface

water were generated for the 26 study areas. Summary statistics of data that include censored values (values less than the

analytical detection limit) were estimated by probabilityplotting methods (Helsel and Hirsch, 1992) or from lognormal maximum-likelihood distributions (Helsel and Cohn,

1988).

The 75th percentile of the selenium concentrations of

water samples from a given area was chosen for comparison

with criteria in deciding whether the water in the area was

contaminated. (The 75th percentile is the concentration that

is exceeded by 25 percent of the samples from the area.) The

median was not used because many of the NIWQP investigators collected only a limited number of samples from a

large area; a study area would have to be extremely contaminated for half of the samples to exceed water-quality criteria. Areas were classified as contaminated if 25 percent or

more of the samples exceeded the U.S. Environmental Protection Agency (USEPA) chronic criterion because, at that

high a percentage, fish and aquatic birds probably are

exposed to contaminated water.

On the basis of selenium concentrations in surface water

(table 2), 12 of the 26 NIWQP areas were classified as selenium contaminated (C, E, F, H, M, N, R, S, U, X, Y, and Z), 2

were classified as seleniferous (B and V), and the remaining

12 were classified as uncontaminated. In the 12 contaminated areas, the filtered-selenium concentrations in 25 percent or more of the surface-water samples equaled or

exceeded 5 μg/L, the USEPA chronic criterion for selenium

for the protection of freshwater aquatic life (table 2, figs. 4

and 5). In the two seleniferous areas, the selenium concentrations in 25 percent or more of the surface-water samples

were equal to or greater than the avian effect level, 3 μg/L,

but less than the USEPA chronic criterion, 5 μg/L. In 7 of the

12 uncontaminated areas (D, I, L, O, P, T, and W), selenium

concentrations in 75 percent or more of the surface-water

samples were less than the analytical reporting limit (1

μg/L); in 3 of these 7 areas (I, L, and P), selenium was not

detected in any surface-water sample. In the 5 other uncontaminated areas (A, G, J, K, and Q), the 75th percentile of

selenium concentrations was 1 to 2 μg/L.

Biota

Selenium is a potent teratogen that can induce deformities of embryos and larvae and cause reproductive failure in

fish and wildlife without otherwise affecting adults (Lemly,

1993). It is the only inorganic constituent in irrigation drain

water that is commonly found in eggs of aquatic birds at concentrations sufficient to cause the death or deformity of an

embryo (Skorupa and Ohlendorf, 1991; Ohlendorf and others, 1993). Because of the sensitivity of avian embryos to

selenium, avian eggs were collected and analyzed for selenium content in 24 of the 26 NIWQP areas.

Selenium concentrations in avian eggs from the 26

NIWQP study areas were evaluated by grouping the data

into sets based on distinct species–site–year permutations.
STUDY METHODS 13

Figure 4. Statistical summary of selenium concentrations in filtered surface water from 26 National Irrigation Water Quality

Program study areas (table 2). Chronic criterion from U.S. Environmental Protection Agency (1987) and avian effect level

from Skorupa and Ohlendorf (1991). USEPA, U.S. Environmental Protection Agency.

EXPLANATION

Point outside upper decile

Upper decile (90th percentile)

USEPA chronic criterion for selenium

Upper quartile (75th percentile)

Median

Lower quartile (25th percentile)

Lower decile (10th percentile)

Point outside lower decile

Avian effect level

NUMBER OF ANALYSES

STUDY AREA

SELENIUM CONCENTRATION, IN MICROGRAMS PER LITER

14 12 10 48 47 343 34 326 13 13 14 14 18 196 38 12 33 43 21 23 54 75 184 120 9 16

ABCDE FGH I J KLMNOPQRS TUVWXY Z

10,000

1,000

100

10

1

Classification of Study Areas by Selenium Concentrations
14 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

Each set of eggs conceptually represents a distinct breeding

population of birds. For example, the 16 American avocet

eggs that were collected from Rasmus Lee Lake, Wyo., in

1988 represent a set; the 86 American avocet eggs that were

collected at the same site in 1989 represent another set. In

some instances, a single egg or a composite sample of two or

more eggs represents the set for a particular breeding population of birds.

The geometric mean of the selenium concentrations of

all the eggs in each set was calculated and is referred to in

this report as the selenium concentration of the egg set.

Ohlendorf (1989) reported that selenium concentrations of

egg sets from uncontaminated areas averaged about 1 to 3

μg/g selenium dry weight. Skorupa and Ohlendorf (1991)

reported that egg sets having selenium concentrations

greater than about 8 μg/g dry weight are associated with significantly reduced hatchability. Data from field sampling

suggest that a threshold for teratogenesis occurs within the

range from 13 to 24 μg/g. A population-level threshold is the

lowest mean concentration of selenium in a set of eggs that

is expected to consistently identify populations in which one

or more hens are producing embryos with selenium-induced

deformities. Population-level egg criteria are not appropriate

for individual-level risk assessment because they do not

identify individuals at risk.

The 26 NIWQP study areas were classified into three

groups on the basis of the maximum mean selenium concentration of representative egg sets (table 2): normal (less than

or equal to 3 μg/g), elevated (greater than 3 μg/g but less than

8 μg/g), and embryotoxic (equal to or greater than 8 μg/g).

Further work since that of Skorupa and Ohlendorf’s (1991)

has indicated that the safe exposure level for some species of

birds is less than 8 μg/g. For instance, for black-necked stilt

embryos, Skorupa (1998) concluded that 6 μg/g represents

the upper boundary of safe exposure, which is only two to

three times the normal background level. Thus, the threshold

for toxic effects used in this report, 8 μg/g, is conservative.

Multiple overt deformities similar to those found in bird

embryos at Kesterson National Wildlife Refuge were found

in bird embryos in 4 of the 26 areas (F, H, N, and Y, table 2).

Deformed birds were found in other areas, but selenium toxicosis was not confirmed; instead, the deformities may represent the normal background rate of deformities that would

occur in any bird population.

Use of a Geographic Information System to

Create Maps

GIS data layers (sets of spatially located digital data)

showing land use, mean annual precipitation, FWSE, and

geology of the United States were obtained or created to use

for data analysis in this report (table 4). Each piece of data

has an associated set of x and y coordinates (for example, latitude and longitude) that are used to locate the data spatially.

Many of the data layers used in this investigation are

available through the NIWQP World Wide Web site, which

can be located by using a search engine to find the acronym

“NIWQP.”

Geologic Data Layers

A GIS data layer of the geology of the United States

derived from the King and Beikman (1974a) geologic map

was released on CD–ROM by Schruben and others (1994).

The CD–ROM may be purchased from the USGS Earth Science Information Center (telephone 1–800–USA–MAPS or

1–800–872–6277 or 1–888–275–8747). It may be obtained

also through the USGS World Wide Web site at

http://mapping.usgs.gov/esic/cdrom

Geologic-map units from the King and Beikman

(1974a) map (table 3) were grouped together to create a GIS

data layer of Upper Cretaceous marine sedimentary rocks,

Tertiary marine sedimentary deposits, and Tertiary continental sedimentary deposits. The following King and Beikman

(1974a) map units of Upper Cretaceous, mainly marine,

stratified sedimentary sequences were combined: uK, uK1,

uK2, uK3, uK3a, uK3b, and uK4. As compiled in this report,

these are called Upper Cretaceous marine sedimentary rocks.

The following map units of Tertiary (Paleocene to Pliocene),

mainly marine, stratified sedimentary sequences were combined: Tx, Te, Te1, Te2, Te3, To, Tm, and Tp. As compiled in

this report, these are called Tertiary marine sedimentary

deposits. The following Paleocene to Pliocene continental

sedimentary deposits were grouped together: Txc, Tel, Tec,

Toc, Tmc, and Tpc. As compiled in this report, these deposits

are called Tertiary continental sedimentary deposits.
STUDY METHODS 15

Climatologic Data Layers

Two GIS data layers of mean annual precipitation in the

United States were obtained and compared. The first data

layer was digitized from Owenby and others’ (1992) map of

normal mean annual precipitation for the years 1961 to 1990.

The other data layer was derived from Daly and others’

(1994) “precipitation–elevation regressions on independent

slopes model” (PRISM), a proprietary data layer available

from George H. Taylor, Oregon State Climatologist (e-mail,

oregon@oce.orst.edu; URL, http://www.ocs.orst.edu). The

PRISM data layer was used because its resolution is much

finer than the first data layer and its contour intervals are

smaller. A GIS data layer of FWSE rates (table 4) was created from Farnsworth and others’ (1982) FWSE map.

The FWSE and PRISM data layers were converted into

gridded surfaces by interpolating between the isograms for

precipitation and evaporation. The gridded surface overestimates annual precipitation for large areas of California,

Arizona, and Nevada because the minimum isogram on the

precipitation map is 10 inches. In these areas, annual precipitation is interpolated uniformly as 10 inches.

The EI data layer was created by dividing evaporation

values by corresponding precipitation values. The resulting

surface was contoured according to the following EI intervals: 0 to 2.5, greater than 2.5 to 3.5, greater than 3.5 to 5.0,

and greater than 5.0.

1 These digital data are documented in accordance with USGS policy (Nebert, 1994) and are on file in USGS office in Carson City, Nev.

2 Version of PRISM used for this study report was obtained from G.H. Taylor, Oregon State Climatologist, October 1993.

3 Published in this report.

TABLE 4. Geographic-information-system data layers used to create maps in this report

[BOR, Bureau of Reclamation; FWSE, free-water-surface evaporation; GIS, geographic information system; NOAA, National Oceanic and

Atmospheric Administration; PRISM, precipitation–elevation regressions on independent slopes model; USGS, U.S. Geological Survey.

~, approximate]

Data type

GIS data layer Data sources

(bold indicates direct source of

published data used in GIS data layer)

Scale of

published map

Name of data layer Year created

Geologic

Bedrock geology KBGE 1994 Schruben and others (1994)

King and Beikman (1974a)

1:2,500,000

1:2,500,000

Climatologic

Evaporation (FWSE) FWSE1 1996 Farnsworth and others (1982) 1:5,000,000

Precipitation (NOAA) NORMPRE1 1994 Rea and Cederstrand (1994)

Owenby and others (1992)

1:5,000,000

Precipitation (PRISM) US_93102 1994 Daly and others (1994) —

Land use

BOR project areas BORAREAS1 1995 Bureau of Reclamation (1988) ~1:5,850,000

Irrigated agricultural land IRRAG1 1996 Earth Resources Observation System

Data Center (1990).

1:7,500,000

National Wildlife Refuges NWRAREAS1 1995 U.S. Fish and Wildlife Service (1988) 1:3,000,000

Interpretive

Evaporation index EI1 1994 Derived from climatologic data layers 31:19,700,000

Susceptible areas SUSCEP251,

SUSCEP301,

SUSCEP351, and

SUSCEP501.

1994 Derived from climatologic and geologic

data layers.

2

1:19,700,000

Use of a Geographic Information System to Create Maps
16 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

Land-Use Data Layers

Data layers and maps showing the locations of Bureau

of Reclamation project areas and National Wildlife Refuges

were derived by digitizing maps prepared by the Bureau of

Reclamation (1988) and the U.S. Fish and Wildlife Service

(1988). The map by the Bureau of Reclamation (1988)

shows the areal extent of most of their project areas; the few

project areas that are shown only as points on this map were

plotted on the USGS data layer BORAREAS (table 4) as

rectangular polygons sized according to the actual project

areas, as reported by the Bureau of Reclamation (1981).

Few designated wildlife areas are shown on nationalscale maps; the U.S. Fish and Wildlife Service (1988) map

shows point locations of only those National Wildlife Refuges that have visitor centers. Therefore the derived land-use

data layer does not include State and local refuges or wildlife-management areas and also excludes National Wildlife

Refuges that do not have visitor centers.

A GIS data layer showing the distribution of irrigated

agricultural land in the Western United States was derived

from Earth Resources Observation System Data Center

(1990) satellite images showing seasonal land-cover regions.

The data layer, which was derived from Advanced Very

High Resolution Radiometer data (commonly called

AVHRR data) by grouping those areas where croplands were

coded as “irrigated agriculture,” has a resolution of 1 square

kilometer (about 0.4 square mile).

FACTORS AFFECTING SELENIUM

CONCENTRATIONS IN WATER

Numerous investigators have identified features common to selenium-contaminated lands. Analysis of data from

the NIWQP data set confirms previous investigators’ conclusions and expands upon their work to produce regional-scale

maps identifying areas in the Western United States susceptible to irrigation-induced selenium contamination. The relations among geology, selenium concentration in water, and

EI (aridity) are shown in figure 5.

Geology

The importance of Upper Cretaceous marine sedimentary rocks as sources of selenium is apparent in the NIWQP

data set. In 8 of the 26 areas, the bedrock is mainly Upper

Cretaceous marine sedimentary rock, and in 4 of the 26

areas, it is Upper Cretaceous marine and Tertiary continental

sedimentary rock (figs. 5A, B; table 2). In 11 of these 12

areas, more than 25 percent of the surface-water samples

contain selenium concentrations equal to or exceeding the

avian effect level, 3 μg/L. Upper Cretaceous marine sedimentary rocks are upland from 3 of the 26 study areas (fig.

5C, table 2) and in 2 of those areas (S and Y, table 2) more

than 25 percent of the surface-water samples contain selenium concentrations equal to or exceeding 5 μg/L (fig. 5C).

The importance of Tertiary marine sedimentary deposits

as sources of selenium is difficult to assess by using the

NIWQP data set. Only two NIWQP study areas (K and Y,

tables 2 and 3) are associated with Tertiary marine sedimentary deposits. In the lower Rio Grande valley in Texas (K),

which is uncontaminated, one background site is on Eocene

marine sedimentary deposits and the remainder of the datacollection sites are on Holocene sedimentary deposits. In the

Tulare Lake Bed area in California (Y), which is contaminated, all the sites are associated with Quaternary sedimentary deposits. Although the principal sources of selenium in

the area are probably Tertiary marine sedimentary deposits,

Upper Cretaceous marine sedimentary rocks also may be

sources. Fujii and Swain (1995, pl. 1) showed that Tertiary

marine sedimentary deposits are within a few miles upland

from the Tulare Lake Bed area and that pre-Tertiary (including Cretaceous) marine sedimentary rocks are about 15 to 20

miles upland. Presser (1994a) stated that the Miocene

Monterey Formation, which consists of marine sedimentary

rocks and is upland from the Tulare Lake Bed area, is seleniferous and is a suspected source of selenium found in the area.

Selenium concentrations in 22 rock samples from the

Monterey Formation ranged from less than 3 to 56 mg/kg;

the median concentration was 10.5 mg/kg, and the mean was

15.5 mg/kg (Piper and Isaacs, 1995). For comparison, selenium concentrations in 527 rock samples from the marine

Niobrara and Pierre Formations of Cretaceous age in South

Dakota ranged from 0 to 113 mg/kg, and the mean was 5.8

mg/kg (Moxon and others, 1939).

Similarly, the importance of Tertiary continental sedimentary deposits as sources of selenium is difficult to assess

by using the NIWQP data set. In 4 of the 26 study areas (N,

R, S, and V, table 2), lower Tertiary (Paleocene–Eocene) continental sedimentary rocks form some or all bedrock, and in

3 of the 26 areas (M, O, and Q, table 2), upper Tertiary

(Pliocene) continental sedimentary rocks form some of the

bedrock (table 3). Selenium contamination occurs in four of

these seven areas (M, N, R, and S), and one is classified as

seleniferous (V). Two of the areas are uncontaminated (O and

Q) and contain Pliocene continental sedimentary deposits,

but no Upper Cretaceous marine sedimentary rocks are in or

near the areas. In four of the five contaminated or seleniferous areas (M, N, R, and V), Upper Cretaceous marine sedimentary rocks form some of the bedrock, and in the fifth (S),

the mountains upland from irrigated lands include Upper

Cretaceous marine sedimentary rocks.
FACTORS AFFECTING SELENIUM CONCENTRATIONS IN WATER 17Figure 5. Relations among selenium concentration, evaporation index (aridity), and geology for 26 National Irrigation Water Quality Prog

Chronic criterion for selenium is from U.S. Environmental Protection Agency (1987), and avian effect level, from Skorupa and Ohlendorf 

Factors Affecting Selenium Concentrations in Water 17 EVAPORATION INDEX

EVAPORA

SEVENTY-FIFTH-PERCENTILE FILTERED SELENIUM CONCENTRATION,

IN MICROGRAMS PER LITER

U.S. Environm chronic criAvian effect lEvaporation i ing seleniu exceed U.S Agency chNational Irrig data—Lette

EXP

A

A

Most of bedrock beneath irrigated lands consists of Upper Cretaceous marine sedimentary rocks

H

F

E

Z

B

C

X

P

300200100

7050302010

75321

<1

B

Bedrock beneath irrigated lands consists of bothUpper Cretaceous marine and Tertiary continental sedimentary rocks

N

M

V

R

C

T

S

Bedrock in mountains upland from irrigated lands includes Upper Cretaceous or both Upper Cretaceous and Tertiary marine sedimentary rocks

D

K

J

U

300200100

7050302010

75321

<1

1 2 3 4 5 6 7 8 910 20 30

Rivers providing water forirrigation traverse UpperCretaceous or both Upper Cretaceous and Tertiarymarine sedimentary rocksupstream from study area

E

A

Q

G

I L DO W

1 2 3 4 5 6 7 8 910 20 30

1 2 3 4 

No association with Upper Cretaceous marine sedimentary rocks
18 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

The best evidence of the importance of rocks and sedimentary deposits of Tertiary age in the NIWQP data set is in

the Ouray subarea of the middle Green River Basin, Utah (N,

table 3). Ground-water samples from this subarea commonly

contain selenium in concentrations exceeding 100 μg/L; the

maximum measured value is 9,300 μg/L (Stephens and

others, 1992, p. 89). Ponds used by wildlife in the subarea

commonly contain selenium at concentrations exceeding

20 μg/L, and deformed bird embryos have been found at

these ponds. All the data-collection sites in the Ouray subarea are associated with Eocene continental sedimentary

deposits (table 3), and the nearest exposure of Upper Cretaceous marine sedimentary rock is about 14 miles upstream.

Trelease and Beath (1949, p. 80) noted that seleniferous

plants occur in parts of the Eocene Uinta Formation, which

is exposed in the area (Stephens and others, 1992).

Knowing where selenium contamination does not occur

is nearly as important as knowing where it does occur. In the

Western United States, areas are unlikely to be contaminated

by selenium if they do not contain and have no nearby Upper

Cretaceous or Tertiary marine sedimentary deposits. Of the

26 areas, 11 fit this description (A, D, I, G, J, K, L, O, Q, U,

and W, figs. 5D, E; tables 2 and 3). Only 2 of these 11 areas

(J and U) have selenium problems; selenium is brought into

both areas in water imported for irrigation. The Salton Sea

(U) is considered to be contaminated on the basis of the concentration of water-borne selenium (table 2), and bird eggs

from the Lower Colorado River valley area (J) contain

embryotoxic concentrations of selenium (William G. Kepner, U.S. Fish and Wildlife Service, written commun., 1989).

The selenium concentration at the 75th percentile in the

remaining 9 areas is less than 3 μg/L; in 5 of these 9 areas, it

is less than the analytical reporting limit (1 μg/L).

Climate

In areas that do not have local geologic sources of selenium such as Upper Cretaceous marine sedimentary rocks

(fig. 5E), selenium concentrations do not increase as aridity

increases. In areas that do have a local geologic source of

selenium (figs. 5A, B), concentrations generally increase as

aridity increases.

Areas having very low evaporation indices are unlikely

to have selenium-contamination problems even if Upper

Cretaceous marine sedimentary rock (fig. 5A) or some other

source of selenium is nearby. This is supported by data from

the Milk River Basin, Mont. (P, fig. 1, table 2), where seleniferous sedimentary deposits are dominant. Data were collected in the Milk River Basin during a year in which

flooding occurred and sufficient water was available to dilute

the contaminants; no selenium was detected in any of the

NIWQP surface-water samples. EI calculated for the flood

year was 1.9, which was the lowest of any for the 26 areas.

Data collected under more normal conditions indicate that

the area is contaminated when precipitation is less abundant.

Presser and others (1994) reported that elevated concentrations of selenium had been measured in a stream in the area.

Lambing and others (1988) reported that selenium concentrations in Lake Bowdoin were 6 μg/L in 1985 and less than

1 μg/L in 1986, when the NIWQP samples were collected.

The distribution of areas in the Western United States

where EI exceeds 2.5 is shown in figure 6; total areas of land

where EI exceeds four threshold values are given in table 5.

An EI value of 2.5 is considered important because it is

between the lowest EI value for an uncontaminated area (1.9

for area P, fig. 5A) and the lowest EI value for a seleniumcontaminated area (2.8 for area C, fig. 5A). An EI value of

3.5 is considered important because the 75th percentile of the

selenium concentrations typically exceeds the USEPA

chronic criterion for selenium (5 μg/L) if EI exceeds 3.5

(figs. 5A, B). In almost one third of the land area in the Western United States, EI is 3.5 or greater and selenium contamination resulting from irrigation of an area is likely if geologic sources of selenium are in or near the area.

Hydrology

Selenium brought into an area can cause contamination

in areas without local geologic sources of selenium. The discharge of irrigation drain water, oil-field brines, coal fly ash,

or mine-dewatering effluent that contains selenium into a

stream can result in contamination in areas hundreds of miles

downstream. An example is the contaminated Salton Sea

area (U, figs. 1 and 5D) in the Imperial Valley in California.

This area is contaminated mainly because selenium is

brought into the area in Colorado River water (Setmire and

others, 1993), although Tertiary marine sedimentary bedrock

exposed in small areas in the mountains to the west may contribute some selenium to the area.

Areas that have terminal lakes or ponds and sources of

selenium within the drainage basin are especially at risk for

becoming contaminated. Evaporative enrichment can cause

elevated selenium concentrations in terminal water bodies.

Also, because the selenium is not flushed out during normal

spring runoff, selenium concentrations can increase because

selenium from several seasons remains in the water.
FACTORS AFFECTING SELENIUM CONCENTRATIONS IN WATER 19

Figure 6. Evaporation index in Western United States. Climate data from Farnsworth and others

(1982) and G.H. Taylor (Oregon State Climatologist, written commun., 1994). For base credit, see

figure 1.

Factors Affecting Selenium Concentrations in Water 19

120°

45°

40°

35°

30°

115° 110° 105° 100°

95°

EXPLANATION

Evaporation index:

2.5 3.0 3.5 5.0

0 250 500 MILES

0 250 500 KILOMETERS
20 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

DEFORMITIES IN AQUATIC BIRDS AND

SELENIUM CONCENTRATIONS IN BIRD EGGS

Selenium poisoning causes multiple overt deformities

in bird embryos (fig. 7); these deformities typically include

hydrocephaly, missing eyes, twisted bills, and deformed

limbs (Hoffman and Heinz, 1988; Hoffman and others,

1988). Bird embryos with multiple overt deformities, like

those in birds from Kesterson Reservoir, were found in 4 of

the 26 NIWQP areas (F, H, N, and Y, table 2). In those four

areas, the median selenium concentrations in surface water

exceeded 10 μg/L (fig. 4), which is twice the USEPA chronic

criterion for the protection of freshwater aquatic life.

TABLE 5. Western United States land areas where

evaporation indexes exceed four threshold values

Evaporation

index

Land area in

Western

United States

(square miles)

Percentage

of total area

of Western

United States

Greater than 2.5 1,024,000 56

Greater than 3.0 709,000 38

Greater than 3.5 566,000 31

Greater than 5.0 237,000 13

Figure 7. Redhead duck embryos from middle Green River Basin study area in Utah. Left embryo

shows twisted bill and other deformities typical of those caused by selenium; right embryo is normal.

Photograph by Bruce Waddell, U.S. Fish and Wildlife Service, 1989.
MAP IDENTIFYING AREAS SUSCEPTIBLE TO SELENIUM CONTAMINATION 21

Deformed birds were found in four other areas (U, V, W, and

X), but the cause of the deformities could not clearly be

attributed to selenium. In at least some of these instances, the

types and numbers of deformities found may represent the

normal background rate found in any natural avian population.

Bird eggs from 24 of the 26 areas were sampled and

analyzed for selenium. Of the areas sampled, 12 were classified as embryotoxic (C, E, F, H, J, N, R, S, V, W, X, and Y,

table 2) because the selenium concentration in at least 1 of

the egg sets exceeded levels associated with significantly

reduced hatchability; 6 areas were classified as normal (A, B,

I, L, O, and P) because the selenium concentrations of all the

egg sets were within the normal range; and the 6 remaining

areas were classified as elevated (D, G, M, Q, I, and U)

because the selenium concentration in at least 1 of the egg

sets was above the normal range.

MAP IDENTIFYING AREAS SUSCEPTIBLE TO

SELENIUM CONTAMINATION

Although many Federal, State, and local irrigationproject areas in the Western United States may be susceptible

to irrigation-induced selenium contamination, limited financial and human resources preclude comprehensive investigations of all irrigated land. Cost-effective tools to identify

areas where irrigation is likely to cause selenium contamination make it possible to target resources effectively toward

investigating those areas at highest risk.

The NIWQP data indicate that irrigation is likely to

result in selenium contamination if geologic sources of selenium are in or near the area and if EI is greater than about

2.5. A map showing areas having this combination of geologic and climatic characteristics was created by intersecting

the GIS geology data layers of Upper Cretaceous and Tertiary marine sedimentary deposits (fig. 2) and the EI data

layer (fig. 6). The resulting map identified about 160,000

square miles of land in the Western United States that is considered to be susceptible to irrigation-induced selenium contamination (table 6, fig. 8). About 52,600 square miles of

land in the Western United States is considered to be even

more susceptible because EI exceeds 3.5.

Land adjacent to areas mapped as susceptible to contamination (fig. 8) also should be treated provisionally as

susceptible because selenium can be transported from source

areas in mountains to irrigated areas in adjacent valleys. In

California, all the areas mapped as susceptible are in mountain ranges where there is no irrigation. Although not indicated on the map, the actual susceptible areas are the

irrigated alluvial fans and valleys at the base of the mountains. Another reason to consider land adjacent to areas

mapped as susceptible is that the parent material for the soils

may be seleniferous Tertiary continental sedimentary deposits. The NIWQP data clearly indicate that selenium contamination can develop in areas of Tertiary continental

sedimentary rocks if Upper Cretaceous marine sedimentary

rocks are nearby.

Assessing Map Reliability

Test Areas

The map correctly classified 22 of the 26 NIWQP study

areas (fig. 9, table 7). Of the 14 areas classified as seleniferous or contaminated, 12 were identified correctly by the map

because they are on or adjacent to areas mapped as susceptible. One of the two areas not so identified was the Salton Sea

area (U, table 7), which could not be identified by the criteria

used to construct the map because selenium is brought into

the Imperial Valley in the water imported for irrigation.

The second contaminated NIWQP area that was not

identified from the map is the Sun River area (X, table 7) in

central Montana. This area is mapped as not susceptible

although it is known to be selenium contaminated. The reason it was not identified is insufficient resolution of climatological data (see section “Accuracy and Precision of Maps”).

TABLE 6. Western United States land areas where evaporation indexes

exceed four threshold values and where bedrock consists of Upper

Cretaceous or Tertiary marine sedimentary rocks

Land where Upper Cretaceous or Tertiary marine

sedimentary rocks form bedrock

Evaporation index Area

(square miles)

Percentage of total

Western United States

Greater than 2.5 160,000 8.7

Greater than 3.0 83,300 4.5

Greater than 3.5 52,600 2.9

Greater than 5.0 17,300 .9

Map Identifying Areas Susceptible to Selenium Contamination 21
22 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

Figure 8. Areas in Western United States that are identified as susceptible to irrigation-induced

selenium contamination on basis of Upper Cretaceous or Tertiary marine sedimentary bedrock

(fig. 2) and evaporation-index values greater than 2.5 (fig. 6). For base credit, see figure 1.

120°

45°

40°

35°

30°

115° 110° 105° 100°

95°

EXPLANATION

Evaporation index in areas where geologic units are mainly 

 Upper Cretaceous or Tertiary marine sedimentary deposits:

2.5 3.0 3.5 5.0

0 250 500 MILES

0 250 500 KILOMETERS

22 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States
MAP IDENTIFYING AREAS SUSCEPTIBLE TO SELENIUM CONTAMINATION 23

Reconnaissance investigations did not identify selenium problems in two NIWQP areas shown on the map as

being at risk for selenium contamination. The first area is the

Sacramento Refuge Complex in California (T, table 7).

Although this area is adjacent to an area mapped as susceptible, it has one of the lowest EI values (2.6) of the NIWQP

areas. Therefore, being near seleniferous rocks may not

result in contamination if EI is low. The second area is the

Milk River Basin, Mont. (P, table 7). All the selenium concentrations in surface water measured there were less than 1

μg/L. As discussed in the section “Climate” under “Factors

Affecting Selenium Concentrations in Water,” all samples

from the Milk River Basin were collected during a year in

which flooding occurred; however, data from Lambing and

others (1988) and Presser and others (1994) show that this

area is contaminated under more normal circumstances.

Whether selenium-contaminated areas can be identified

correctly from the map also was assessed by plotting the

locations of areas where selenium investigations have been

done as part of programs other than the NIWQP. The classic

example of irrigation-induced selenium contamination,

Kesterson Reservoir in Merced County, Calif., is adjacent to

an area mapped as susceptible (fig. 9). Data from Kesterson

Reservoir indicate the importance of provisionally treating

areas as susceptible when they are adjacent to areas mapped

as susceptible. Selenium in drain water discharged to Kesterson Reservoir originated in the Cretaceous and Tertiary

marine sedimentary rocks and deposits in the California

coast ranges upland from irrigated soils (Presser, 1994a).

Selenium contamination was discovered recently at Red

Rock Ranch (fig. 9), an agroforestry experimental farm south

of Kesterson Reservoir. The Red Rock Ranch is next to an

area mapped as susceptible. Irrigation drain water at the Red

Rock Ranch was reused for irrigation of salt-tolerant plants

and ultimately contained extremely high concentrations of

selenium; selenium concentrations were 1,200 μg/L in the

water used for the last crop (M.A. Martin, Westside

Resource Conservation District, oral commun., 1996) and

more than 11,000 μg/L in shallow evaporation ponds (California Regional Water Quality Control Board, Central Valley

Region, unpub. data, 1996). Black-necked stilts nesting in

the area were exposed to the water and more than 60 percent

of the eggs sampled contained deformed embryos (B.E. Van

Vorts, California Regional Water Quality Control Board,

Central Valley Region, written commun., 1996).

In the mid-1980’s, the West Oakes area of North Dakota

(fig. 9) was investigated for potential selenium problems

because of the area’s association with Cretaceous sedimentary rocks (Goolsby and others, 1989). The map classified

this area as not susceptible because EI for the area is less than

2.5. That classification is supported by data from Goolsby

and others (1989). They found a maximum selenium concentration of 4 μg/L in 63 samples from 23 subsurface drains

and a maximum of 1.4 μg/L in 137 surface-water samples

from 7 sites not far from West Oakes.

The reliability of the map also was assessed by evaluating data from NIWQP investigations that were not analyzed for this study because the data were not available earlier. The Wind River Indian Reservation in Wyoming and the

Emery Project and Scofield Project areas in Utah are on and

adjacent to land mapped as susceptible to selenium contamination (fig. 9). Data for the Wind River Indian Reservation,

collected during 1992–1993 (Grasso and others, 1995), support classification of the area as susceptible. They found that

6 of 14 surface-water samples from the Little Wind Irrigation

Unit had selenium concentrations that exceeded 5 μg/L and

the maximum concentration was 17 μg/L. Stephens and others’ (1997) data for the Emery Project and Scofield Project

areas, collected during 1994, support classification of the

areas as susceptible. They found that 9 of 45 surface-water

samples from the areas had selenium concentrations that

exceeded 5 μg/L and the maximum concentration was

46 μg/L.

The Walker River Indian Reservation in Nevada is not

on land mapped as susceptible (fig. 9). Thodal and Tuttle’s

(1996) data, collected in the area during 1994, support classification of the area as not susceptible. Selenium was not

detected in any of 25 surface-water samples from the area.

The biological significance of the map was assessed

using selenium concentrations in avian eggs and fish collected by the NIWQP. The map is based on the results of an

analysis of geologic, hydrologic, climatic, and water-quality

data. Biological data were not used in that analysis and provide an independent test of the map. In 12 of the NIWQP

areas, the mean selenium concentration of at least one set of

avian eggs was classified as embryotoxic (table 2 and fig. 9).

The map identified 9 of those 12 areas as susceptible to irrigation-induced selenium contamination.

Assessing Map Reliability
24 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

120°

45°

40°

35°

30°

115° 110° 105° 100°

95°

EXPLANATION

National Irrigation Water Quality Program study areas:

Area classified as uncontaminated and where some bird eggs contain 

 embryotoxic concentrations of selenium

Area classified as seleniferous or contaminated and where some bird 

 eggs contain embryotoxic concentrations of selenium

Area or site where surface water is not selenium contaminated

Area or site where surface water is selenium contaminated

W

Y

Test areas and other areas or sites discussed in text: West

Oakes

Scofield

Area classified as uncontaminated and where bird eggs do not contain 

 embryotoxic concentrations of selenium

Area classified as seleniferous or contaminated but where bird eggs do 

 not contain embryotoxic concentrations of selenium

T

M

0 250 500 MILES

0 250 500 KILOMETERS

2.5 3.0 3.5 5.0

Evaporation index in areas where geologic units are mainly 

 Upper Cretaceous or Tertiary marine sedimentary deposits:

West Oakes

Wind

River

Kesterson

Reservoir

Red Rock

Ranch

Walker

River

Scofield

Emery

Red Rock

Ranch

West

Oakes

Wind

River

Kesterson

Reservoir

Red Rock

Ranch

Walker

River

Scofield

Emery

Red Rock

Ranch

A

B

D

G

K

L

M

O

Q

T

U

Z

P

I

A

B

D

G

K

L

M

O

Q

T

U

Z

P

I

X

C

E

F

H

J

N

R

S

V

W

Y

X

C

E

F

H

J

N

R

S

V

W

Y

24 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States
MAP IDENTIFYING AREAS SUSCEPTIBLE TO SELENIUM CONTAMINATION 25

The three areas classified as embryotoxic in table 2 that

were not identified from the map are the Sun River area in

Montana, the lower Colorado River valley in California and

Arizona, and the Stillwater Wildlife Management Area in

Nevada (X, J, and W, table 2). Embryotoxicity in the Sun

River area was not identified because of insufficient resolution of climatological data (see section “Accuracy and Precision of Maps”). The biological classification of the lower

Colorado River valley as embryotoxic is not concordant with

its classification as uncontaminated on the basis of waterborne selenium (table 2). The bird eggs were from a bird that

feeds in backwater areas where circulation is minimal (William G. Kepner, U.S. Fish and Wildlife Service, written commun., 1989), whereas almost all the water samples were

from the mainstem of the Colorado River, where selenium

concentrations are typically 1 to 2 μg/L. Water samples from

these backwater areas, where evaporation can increase selenium concentrations to toxic levels, were not collected as

part of the NIWQP. In the Stillwater Wildlife Management

Area, all the embryotoxic sets of eggs were from two isolated sets of ponds. The source of selenium is not known;

however, near the ponds are Pliocene sedimentary deposits

that are interlayered with basalts and tuffs (Willden and

Speed, 1974) and may be seleniferous because of their association with the volcanic material.

Three areas (B, M, and P, table 2) were identified as susceptible from the map, but selenium concentrations in bird

eggs were not embryotoxic. In these areas, however, sample

sizes were inadequate to determine whether selenium contamination is a problem. Three or fewer sets of eggs were

collected, and not enough birds of appropriate feeding guilds

were available for sampling. Selenium concentrations in fish

tissue from these areas were compared with values presented

by Lemly (1995) to assess the potential for reproductive

impairment in fish. In two of the three areas (B and M), the

hazard is high for selenium-induced reproductive impairment in some fish.

Deformities of birds directly attributable to selenium

were found in 4 of the 12 embryotoxic areas (F, H, N, and Y,

table 2) and the map identified all 4 as susceptible. The map

cannot be tested by comparison with areas where no deformities were found. That deformities were not found in some

areas does not mean that none occur. In some areas, no latestage embryos were examined for deformities, and some

embryos examined were not from areas where selenium concentrations measured in eggs or water were high.

Correctness of Analysis

The reliability of any map identifying areas susceptible

to irrigation-induced selenium contamination depends on

several factors. First, the analysis that is the basis for the map

must be correct and complete; it cannot be based on incorrect

or incomplete analysis of critical factors that cause irrigation-induced selenium contamination. Second, the most

important factors must be mappable. Third, the reliability of

the map depends on the accuracy and precision of the maps

used to portray the distribution of the critical factors.

The basic assumptions for the map in figure 8 are that

application of irrigation water mobilizes selenium only from

soils derived from Upper Cretaceous or Tertiary marine sedimentary deposits and that subsequent evaporative enrichment is the principal factor that determines whether

concentrations of selenium reach toxic levels. These

assumptions are of fundamental importance because in some

instances when they were not met, areas having known selenium problems could not be identified from the map.

In this report, areas are considered geologically susceptible to irrigation-induced selenium contamination only if

the bedrock in the area consists of Upper Cretaceous or Tertiary marine sedimentary rocks or deposits. Thus, areas susceptible to selenium contamination would not be identified

from figure 8 if the soils are derived from other seleniferous

rocks. Upper Cretaceous marine sedimentary rocks were

included because generally they are seleniferous and are

widespread in the Western United States. Tertiary marine

sedimentary deposits were included because they also may

be seleniferous. Their inclusion does not greatly increase the

amount of land that could be falsely identified as susceptible;

even if they are not seleniferous, they are not widespread in

arid areas of the Western United States. Tertiary continental

sedimentary deposits were not included for several reasons.

The occurrence of selenium in Tertiary continental sedimentary deposits is localized; not all are seleniferous. Because

these rocks are very widespread their inclusion could greatly

increase the amount of land falsely identified as susceptible

to contamination.

In this report, areas are considered climatically susceptible to irrigation-induced selenium contamination only if

the EI exceeds about 2.5. This value for EI is empirical and

is based only an on analysis of conditions at the NIWQP

study areas. Thus, susceptible areas would not be identified

from figure 8 if selenium concentrations exceed water-quality criteria in areas of minimal or no subsequent evaporative

enrichment. This may happen in areas where the soils are

much more seleniferous than in areas studied by the NIWQP.

Figure 9. National Irrigation Water Quality Program study

and test areas in relation to areas in Western United States

that are identified as susceptible to irrigation-induced selenium contamination (fig. 8). For base credit, see figure 1.

Correctness of Analysis
26 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

1 Criteria used: uncontaminated (UC), 75th percentile of selenium concentrations in surface water is less than 3 micrograms per liter; seleniferous (S), 75th percentile is at least 3

but less than 5 micrograms per liter; contaminated (C), 75th percentile is at least 5 micrograms per liter. Avian effect level (Skorupa and Ohlendorf, 1991) is 3 micrograms per liter; chronic

criterion for protection of freshwater aquatic life (U.S. Environmental Protection Agency, 1987) is 5 micrograms per liter.

2 Mean annual precipitation for NIWQP data-collection sites as interpolated from PRISM data layer.

3 Annual precipitation based on data in published reports of reconnaissance and detailed studies (table 1); where range of values was shown, value used here is midpoint of range.

4 Mean annual evaporation for NIWQP data-collection sites as interpolated from FWSE data layer.

5 Mean EI for NIWQP data-collection sites as interpolated from EI data layer.

6 EI calculated by dividing FWSE values by actual annual precipitation.

7 Precipitation and EI for this area were not estimated by using data layers because precipitation along coastal and international boundaries is modeled as 0 inch in PRISM data layer.

TABLE 7. Reliability of map assessment of study-area susceptibility and interpolation of climatic variables

[C, contaminated; EI, evaporation index; FWSE, free-water surface evaporation; NIWQP, National Irrigation Water Quality Program; PRISM, precipitation–elevation

regressions on independent slopes model; S, seleniferous; UC, uncontaminated; —, no data]

Area

identifier Study area Study-area

classification1 Map

assessment

Precipitation

(inches per year)

FWSE

rate4

(inches

per

year)

EI

Map2 Actual3 Map5 Actual6

A American Falls Reservoir, Idaho UC Correct 11.2 10.9 41 3.7 3.7

B Angostura Reclamation Unit, South Dakota S Correct 15 16.4 46 3.0 2.8

C Belle Fourche Reclamation Project, South Dakota C Correct 15.8 14.4 40 2.6 2.8

D Columbia River Basin, Washington UC Correct 10 8 40 4.0 5.0

E Dolores–Ute Mountain area, Colorado C Correct 14 12 53 4.0 4.4

F Gunnison River Basin–Grand Valley Project, Colorado C Correct 11.1 9.3 50 4.6 5.4

G Humboldt River area, Nevada UC Correct 10 5.5 45 4.5 8.1

H Kendrick Reclamation Project, Wyoming C Correct 14.7 12 44 3.0 3.7

I Klamath Basin Refuge Complex, California–Oregon UC Correct 20 13 39 2.0 3.0

J Lower Colorado River valley, California–Arizona UC Correct 10 4.5 85 8.5 18.9

K Lower Rio Grande valley, Texas UC Correct (7

) 25.9 57 (7) 2.2

L Malheur National Wildlife Refuge, Oregon UC Correct 11.2 10 43 4.0 4.3

M Middle Arkansas River Basin, Colorado–Kansas C Correct 13.4 14.6 58 4.3 4.0

N Middle Green River Basin, Utah C Correct 10 7.6 43 4.2 5.7

O Middle Rio Grande, New Mexico UC Correct 10.4 9.4 64 6.2 6.8

P Milk River Basin, Montana UC Incorrect 15 12 40 2.7 3.3

Q Owyhee–Vale Reclamation Project areas, Oregon–Idaho UC Correct 10.5 9.5 43 4.1 4.5

R Pine River area, Colorado C Correct 14.7 14 49 3.4 3.5

S Riverton Reclamation Project, Wyoming C Correct 10 8.1 40 4.0 4.9

T Sacramento Refuge Complex, California UC Incorrect 20 18.5 48 2.5 2.6

U Salton Sea area, California C Incorrect 10 3 73 7.3 24.5

V San Juan River area, New Mexico S Correct 10 7.6 56 5.6 7.4

W Stillwater Wildlife Management Area, Nevada UC Correct 10 5.3 53 5.2 10.0

X Sun River area, Montana C Incorrect 18.9 12 36 1.9 3.0

Y Tulare Lake Bed area, California C Correct 10 5.5 61 6.3 11.1

Z Vermejo Project area, New Mexico C Correct 15 13.8 54 3.6 3.9

26 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States
MAP IDENTIFYING AREAS SUSCEPTIBLE TO SELENIUM CONTAMINATION 27

In those areas, application of irrigation water may mobilize

so much selenium that water-quality criteria are exceeded

even though EI is less than 2.5, which is the minimum value

used in figure 8 to identify susceptible areas.

Because EI is computed using mean annual precipitation and evaporation, the map shows susceptibility under

average climatic conditions. During drought conditions or

other periods of reduced water availability, selenium problems could develop in areas not identified from the map as

being susceptible. Conversely, areas identified as susceptible

may not have selenium problems during wetter than average

periods.

Accuracy and Precision of Maps

The geologic map in figure 2 identifies areas of the

Western United States underlain by potentially seleniferous

bedrock and indicates areas where soils are likely to have

been derived from seleniferous bedrock. The geology presented in figures 2 and 8 was derived from the King and

Beikman (1974a) map, which was published at a scale of

1:2,500,000. The error inherent from that scale is equivalent

to a radial distance of about 4,200 ft. The page-size maps in

this report are at a scale of approximately 1:20,000,000. The

error inherent from that scale is a distance of about 33,000 ft.

Compilation of the geologic map of the United States

required much generalization. King and Beikman (1974b)

described the process by which geologic units from larger

scale maps were combined into broader map units and their

contacts simplified to produce a pattern that is discernible at

the scale of 1:2,500,000. At that scale, the minimum area that

can be resolved is several square miles. Precisely locating

contacts between geologic units is problematic because lines

separating units on the geologic map are the equivalent of

several hundred feet wide.

The King and Beikman (1974a) map is primarily a bedrock map and therefore does not show all surficial geology.

Upper Cretaceous marine sedimentary rocks that form the

bedrock are, in places, buried under much younger glacial

deposits that blanket large parts of the northern interior

States. (Such deposits are purposely not shown by King and

Beikman.) Thus, seleniferous rocks of Cretaceous age may

not be the parent material of the overlying soils in areas

affected by Pleistocene glaciation even though they are

mapped as being the bedrock.

For 22 of the 26 NIWQP study areas, EI values computed from the EI map are less than the actual values (table

7). Inaccuracy and imprecision in the EI map (fig. 6) are

compounded by interpolating values between isograms on

the GIS data layers of precipitation and evaporation. Errors

from interpolation between isograms are largest where the

contour intervals are large, the isograms are widely spaced,

and no maximum or minimum values are shown.

For 13 of the study areas, the characteristics of the isohyets in the PRISM data layer result in overestimating

annual precipitation by at least 20 percent (table 7). One type

of error in interpolation results from widely spaced isohyets.

For example, the Sun River area in Montana (X, fig. 1, table

2) is between the 10- and 20-inch isohyets. The actual annual

precipitation in the area is about 12 inches, but precipitation

for the area as computed by interpolation of the PRISM data

layer is 18.9 inches (table 7). Similarly, a 20- inch isohyet

forms a nearly closed loop around the Klamath Basin Refuge

Complex (I, fig.1, table 2) area in California and Oregon and

thus effectively isolates the area from the 10-inch isohyet.

Consequently, annual precipitation in the area was computed

as 20 inches, whereas actual precipitation is only about 13

inches.

Another type of error results from interpolation in morearid areas because the minimum isogram in the precipitation

data layer is 10 inches per year. Precipitation values are estimated from the data layer as 10 inches per year for large

areas of California, Arizona, and Nevada when in fact they

are much less. Because of this type of error, interpolation

results in EI values that are 50 to 70 percent too low for study

areas such as the Salton Sea (Calif.) or Humboldt River

(Nev.) areas (U and G, table 7), where the actual annual precipitation is 3 to 5 inches rather than 10 inches.

Errors that result from interpolating between isograms

on the evaporation data layer are relatively smaller than

those from the precipitation data layer. On the FWSE map,

the contour interval is either 4 or 5 inches per year except in

areas where the annual evaporation rate is greater than 80

inches. Furthermore, on the FWSE map the contour interval

is about 10 percent of the values contoured. On the precipitation map, however, the contour interval is commonly the

same as or greater than the values contoured.

The reliability of the map of susceptible areas is affected

more by inaccuracy and imprecision in the climate map (fig.

6) than in the geologic map (fig. 2). Because the climate map

commonly underestimates EI, the most likely type of error is

a false negative—that is, identification of an area as not susceptible when in fact it is susceptible. The Sun River area in

central Montana was incorrectly classified as not susceptible

(table 7) because, although actual EI for the Sun River area

is 3.0, EI computed from climatic data layers is 1.9. The

parts of the map of susceptibility (fig. 8) most likely to be

unreliable are along the boundaries between the white and

grey areas. Large areas in central Montana and South Dakota

may be more susceptible to irrigation-induced selenium contamination than are indicated in figure 8.

Accuracy and Precision of Maps
28 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

Land Use Within Susceptible Areas

Because maps are visual, broad geographic areas susceptible to contamination can be identified easily. An additional advantage of maps is that overlays of land-use data can

be created so that specific management areas that may have

problems can be identified quickly.

Many Bureau of Reclamation projects are within areas

mapped as susceptible to irrigation-induced selenium contamination (fig. 10). Some of these project areas have been

investigated by the NIWQP. Maps showing locations of all

DOI-managed areas and DOI trust lands could not be found.

For example, maps showing all Indian Reservations where

land is irrigated for agriculture could not be found.

A few National Wildlife Refuges are in susceptible

areas (fig. 11); most are in areas that have been investigated

by the NIWQP. The fact that only a few refuges are within

susceptible areas, however, should not be taken as evidence

that risk to wildlife in the Western United States is small.

Many important wildlife habitats are not shown on the map.

For example, in figure 11 only four National Wildlife Refuges are shown in Colorado, and none of the more than 200

Colorado Division of Wildlife areas (Colorado Division of

Wildlife, 1980) are shown.

More than 66,400 square miles of land in the Western

United States is irrigated for agricultural purposes. Derived

in part from Earth Resources Observation System Data Center (1990) satellite imagery, figure 12 identifies all irrigated

agricultural lands that are susceptible to contamination

regardless of which Federal, State, local or private entity

provides the water. About 4,100 square miles of irrigated

land is within areas mapped as susceptible. In addition, large

areas of irrigated land are adjacent to susceptible areas. More

than 1,000 square miles of land in the western San Joaquin

Valley is irrigated for agriculture (San Joaquin Valley Drainage Program, 1990), and much of that land is adjacent to

areas identified as susceptible to irrigation-induced selenium

contamination.

DISCUSSION AND SUMMARY

In areas having local geologic sources of selenium,

application of water to the soil mobilizes the selenium by

dissolving it and creating hydraulic gradients that result in

the discharge of seleniferous ground water into irrigation

drains. Drain water can carry the selenium to areas used by

wildlife, and, depending on the hydrology and climate of the

area, toxic concentrations of selenium can result. Because

selenium is toxic at very low concentrations, knowing where

selenium contamination may occur is important so that

appropriate measures can be taken to protect wildlife.

Upper Cretaceous marine sedimentary rocks are the

most widespread seleniferous rocks in the Western United

States. Selenium concentrations in water are elevated in all

but 1 of the 12 NIWQP study areas where irrigated areas are

on or adjacent to Upper Cretaceous marine sedimentary

rocks. Research in the San Joaquin Valley in California has

demonstrated that Tertiary marine sedimentary deposits

upland from irrigated areas also can be important sources of

selenium. The degree of contamination that results from

mobilization of selenium by irrigation water depends greatly

on the aridity and hydrology of the area.

A map was created using geologic and climatic information to identify areas in the Western United States susceptible to irrigation-induced selenium contamination. This map

cannot be used to identify every area where irrigationinduced selenium contamination may be found because

some important hydrologic factors, such as whether the area

contains terminal ponds and whether selenium is brought

into the area (for example, in water imported for irrigation),

are not readily mapped. However, the map presented in this

report, although based only on the geology and climate, does

identify most of the NIWQP areas where irrigation-induced

selenium contamination is known.

Conclusions that an area is not at risk on the basis of

these maps should be examined critically if the soils and soilparent materials in the area are known to be very seleniferous. In such cases, nonarid areas that are not identified from

the map as being susceptible to irrigation-induced selenium

contamination because the EI is less than 2.5 may in fact be

susceptible. In an area of very seleniferous soils, application

of irrigation water could possibly result in such large

amounts of selenium being mobilized that toxic concentrations occur even with very little evaporative enrichment.

Further, the map is based on average climatic conditions, and

problems may not occur during normal or wet years but

could occur during drought years and other periods of

reduced water availability.

The reliability of the maps could be improved if they

were prepared from more-detailed or larger scale geologic

and climatic maps. The susceptible areas in Montana, for

example, could be identified better if a State map of precipitation, such as that by Parret and Omang (1986), were used.

Creating a better national map of precipitation by compositing currently available State-scale maps is problematic.

Because State maps are produced by many different agencies, different periods of record and precipitation contour

intervals typically are used on maps of adjacent States. Furthermore, even if the contours were the same, laying maps of

adjacent States next to each other does not mean that the contours will meet at the State boundaries. Similar problems

would be encountered in an attempt to composite geology or

other data from State-scale maps.
DISCUSSION AND SUMMARY 29

Figure 10. Bureau of Reclamation (1988) project areas in relation to areas in Western United States

that are identified as susceptible to irrigation-induced selenium contamination (fig. 8). For base credit,

see figure 1.

120°

45°

40°

35°

30°

115° 110° 105° 100°

95°

EXPLANATION

Bureau of Reclamation project area

2.5 3.0 3.5 5.0

0 250 500 MILES

0 250 500 KILOMETERS

Evaporation index in areas where geologic 

 units are mainly Upper Cretaceous or 

 Tertiary marine sedimentary deposits:

Land Use Within Susceptible Areas
30 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

Figure 11. National Wildlife Refuges (U.S. Fish and Wildlife Service, 1988) in relation to areas in Western

United States that are identified as susceptible to irrigation-induced selenium contamination (fig. 8).

For base credit, see figure 1.

120°

45°

40°

35°

30°

115° 110° 105° 100°

95°

EXPLANATION

National Wildlife Refuge

2.5 3.0 3.5 5.0

0 250 500 MILES

0 250 500 KILOMETERS

Evaporation index in areas where geologic 

 units are mainly Upper Cretaceous or 

 Tertiary marine sedimentary deposits:
DISCUSSION AND SUMMARY 31

FIGURE 12. Irrigated agricultural lands in relation to areas in Western United States that are identified

as susceptible to irrigation-induced selenium contamination (fig. 8). Irrigation data was derived in part

from Earth Resources Observation System Data Center (1990) satellite images. For base credit, see

figure 1.

120°

45°

40°

35°

30°

115° 110° 105° 100°

95°

EXPLANATION

Area susceptible to contamination—Where evaporation 

 index is greater than 2.5 and where geologic units are mainly 

 Upper Cretaceous or Tertiary marine sedimentary deposits

Irrigated agricultural land

0 250 500 MILES

0 250 500 KILOMETERS

Discussion and Summary
32 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

That the maps in this report identified all four NIWQP

study areas where deformed embryos were found, and most

of the areas where sets of bird eggs contained embryotoxic

concentrations of selenium, demonstrates the biological significance of the map. Four NIWQP study areas are within

areas mapped as susceptible, but embryotoxic concentrations of selenium were not observed in bird eggs. These sites

may warrant sampling efforts that are more extensive, both

taxonomically and spatially.

About 4,100 square miles of irrigated land in the Western United States was identified from maps as being susceptible to irrigation-induced selenium contamination. Large

areas of irrigated agricultural land adjacent to areas identified as susceptible from the map are also at risk. The map

presented here is intended to be used as a screening and ranking tool by managers. After ranking the likelihood of contamination in several areas, resources can be directed toward

assessing selenium contamination in areas where it is most

likely.

REFERENCES CITED

Bartolino, J.R., Garrabrant, L.A., Wilson, Mark, and Lusk, J.D.,

1996, Reconnaissance investigation of water quality, bottom

sediment, and biota associated with irrigation drainage in the

Vermejo Project area and the Maxwell National Wildlife

Refuge, Colfax County, northeastern New Mexico, 1993: U.S.

Geological Survey Water-Resources Investigations Report

96–4157, 89 p.

Berrow, M.L., and Ure, A.M., 1989, Geological materials and soils,

in Ihnat, M., ed., Occurrence and distribution of selenium:

Boca Raton, Fla., CRC Press, p. 213–242.

Blanchard, P.J., Roy, R.R., and O'Brien, T.F., 1993, Reconnaissance

investigation of water quality, bottom sediment, and biota

associated with irrigation drainage in the San Juan River area,

San Juan County, northwestern New Mexico, 1990–91: U.S.

Geological Survey Water-Resources Investigations Report

93–4065, 141 p.

Bureau of Reclamation, 1981, Water and Power Resources Service—Project data: Washington, D.C., U.S. Government

Printing Office, 1463 p.

———1988, Western United States showing location of Bureau of

Reclamation projects: Washington, D.C., U.S. Government

Printing Office GPO 856–745, Map no. X–D–4151, scale

~1:5,850,000.

Butler, D.L., Kreuger, R.P., Campbell–Osmundson, Barbara, and

Jenson, E.G., 1995, Reconnaissance investigation of water

quality, bottom sediment, and biota associated with irrigation

drainage in the Dolores Project area, southwestern Colorado

and southeastern Utah, 1990–91: U.S. Geological Survey

Water-Resources Investigations Report 94–4041, 126 p.

Butler, D.L., Krueger, R.P., Osmundson, B.C., Thompson, A.L.,

Formea, J.J., and Wickman, D.W., 1993, Reconnaissance

investigation of water quality, bottom sediment, and biota

associated with irrigation drainage in the Pine River Project

area, southern Ute Indian Reservation, southwestern Colorado

and northwestern New Mexico, 1988–89: U.S. Geological

Survey Water-Resources Investigations Report 92–4188,

105 p.

Butler, D.L., Krueger, R.P., Osmundson, B.C., Thompson, A.L.,

and McCall, S.K., 1991, Reconnaissance investigation of

water quality, bottom sediment and biota associated with

irrigation drainage in the Gunnison and Uncompahgre River

Basins and at Sweitzer Lake, west-central Colorado, 1988–89:

U.S. Geological Survey Water-Resources Investigations

Report 91–4103, 99 p.

Butler, D.L., Wright, W.G., Hahn, D.A., Krueger, R.P., and

Osmundson, B.C., 1994, Physical, chemical, and biological

data for detailed study of irrigation drainage in the Uncompaghre Project area and in the Grand Valley, west-central Colorado, 1991–92: U.S. Geological Survey Open-File Report

94–110, 146 p.

Butler, D.L., Wright, W.G., Stewart, K.C., Osmundson, B.C.,

Krueger, R.P., and Crabtree, D.W., 1996, Detailed study of

selenium and other constituents in water, bottom sediment,

soil, alfalfa, and biota associated with irrigation drainage in

the Uncompahgre Project area and in the Grand Valley, westcentral Colorado, 1991–93: U.S. Geological Survey WaterResources Investigations Report 96–4138, 136 p.

Byers, H.G., Williams, K.T., and Lakin, H.W., 1936, Selenium in

Hawaii and its probable source in the United States: Industrial

and Engineering Chemistry, v. 28, no. 7, p. 821–823.

Colorado Division of Wildlife, 1980, Guide to Colorado’s State

Wildlife Areas—A listing of 214 Division of Wildlife properties with 21 maps showing 37 selected State Wildlife Areas:

Colorado Outdoors Magazine Publication, 32 p.

Daly, Christopher, Neilson, R.P., and Phillips, D.L., 1994, A statistical–topographic model for mapping climatological precipitation over mountainous terrain: Journal of Applied Meteorology, v. 33, no. 2, p. 140–158.

Deason, J.P., 1986, U.S. Department of the Interior investigations

of irrigation-induced contamination problems, in Summers,

J.B., and Anderson, S.S., eds., Toxic substances in agricultural

water supply and drainage—Defining the problems—Proceedings of regional meeting of the U.S. Committee on Irrigation and Drainage, September 1986, Boulder, Colo.: Washington, D.C., U.S. Government Printing Office, p. 201–210.

Dileanis, P.D., Schwarzbach, S.E., Bennett, Jewel, and others,

1996, Detailed study of water quality, bottom sediment, and

biota associated with irrigation drainage in the Klamath Basin,

California and Oregon, 1990–92: U.S. Geological Survey

Water-Resources Investigations Report 95–4232, 68 p.
REFERENCES CITED 33

Dileanis, P.D., Sorenson, S.K., Schwarzbach, S.E., and Maurer,

T.C., 1992, Reconnaissance investigation of water quality,

bottom sediment, and biota associated with irrigation drainage

in the Sacramento National Wildlife Refuge Complex, California, 1988–89: U.S. Geological Survey Water-Resources

Investigations Report 92–4036, 79 p.

Earth Resources Observation System Data Center, 1990, Prototype

1990 conterminous U.S. land-cover characteristics data set

[CD–ROM]: U.S. Geological Survey, Earth Resources Observation System Data Center.

Embry, S.S., and Block, E.K., 1995, Reconnaissance investigation

of water quality, bottom sediment, and biota associated with

irrigation drainage in the Columbia Basin Project, Washington, 1991–92: U.S. Geological Survey Water-Resources

Investigations Report 95–4007, 144 p.

Engberg, R.A., and Sylvester, M.A., 1993, Concentrations, distribution, and sources of selenium from irrigated lands in Western United States: Journal of Irrigation and Drainage Engineering, v. 119, no. 3, p. 522–536.

Farnsworth, R.K., Thompson, E.S., and Peck, E.L., 1982, Annual

free water surface evaporation (shallow lake), 1956–70, in

Evaporation atlas for the contiguous 48 United States:

National Oceanic and Atmospheric Administration Technical Report NWS 33, map 3, scale 1:5,000,000.

Feltz, H.R., Engberg, R.A., and Sylvester, M.A., 1991, Reconnaissance investigations of the effects of irrigation drainage

on water quality, bottom sediment, and biota in the Western

United States, in Mallard, G.E., and Aronson, D.A., eds.,

U.S. Geological Survey Toxic Substances Hydrology Program—Proceedings of the technical meeting, Monterey,

Calif., March 11–15, 1991: U.S. Geological Survey WaterResources Investigations Report 91–4034, p. 319–323.

Fujii, Roger, and Swain, W.C., 1995, Areal distribution of selected

trace elements, salinity, and major ions in shallow ground

water, Tulare Basin, southern San Joaquin Valley, California:

U.S. Geological Survey Water-Resources Investigations

Report 95–4048, 67 p.

Goolsby, D.A., Severson, R.C., Wilson, S.A., and Webber, K.,

1989, Geochemistry of soils and shallow ground water, with

emphasis on arsenic and selenium, in part of the Garrison

Diversion Unit, North Dakota, 1985–87: U.S. Geological Survey Water-Resources Investigations Report 89–4104, 132 p.

Grasso, D.N, Jennings, M.E., and Sadler, W.J., 1995, Field screening of water quality, bottom sediment, and biota associated

with irrigation drainage, Wind River Indian Reservation,

Wyoming, 1992–93: U.S. Geological Survey Open-File

Report 95–121, 41 p.

Greene, E.A., Sowards, C.L., and Hansmann, E.W., 1990, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the Angostura

Reclamation Unit, southwestern South Dakota, 1988–89: U.S.

Geological Survey Water-Resources Investigations Report

90–4152, 75 p.

Hallock, R.J., and Hallock, L.L., eds., 1993, Detailed study of irrigation drainage in and near wildlife management areas, westcentral Nevada, 1987–90—Part B, Effect on biota in Stillwater

and Fernley Wildlife Management Areas and other nearby

wetlands: U.S. Geological Survey Water-Resources Investigations Report 92–4024–B, 84 p.

Helsel, D.R., and Cohn, T.A., 1988, Estimation of descriptive

statistics for multiply censored water-quality data: Water

Resources Research, v. 24, no. 12, p. 1997–2004.

Helsel, D.R., and Hirsch, R.M., 1992, Statistical methods in water

resources: New York, Elsevier, 522 p.

Hoffman, D.J., and Heinz, G.H, 1988, Embryotoxic and teratogenic

effects of selenium in the diet of mallards: Journal of Toxicology and Environmental Health, v. 24, p. 477–490.

Hoffman, D.J., Ohlendorf, H.M., and Aldrich, T.W., 1988, Selenium teratogenesis in natural populations of aquatic birds in

central California: Archives of Environmental Contamination

and Toxicology, v. 17, p. 519–525.

Hoffman, R.J., 1994, Detailed study of irrigation drainage in and

near wildlife management areas, west-central Nevada, 1987–

90—Part C, Summary of irrigation-drainage effects on water

quality, bottom sediment, and biota: U.S. Geological Survey

Water-Resources Investigations Report 92–4024–C, 32 p.

Hoffman, R.J., Hallock, R.J., Rowe, T.G., Lico, M.S., Burge, H.L.,

and Thompson, S.P., 1990, Reconnaissance investigation of

water quality, bottom sediment, and biota associated with irrigation drainage in and near Stillwater Wildlife Management

Area, Churchill County, Nevada, 1986–87: U.S. Geological

Survey Water-Resources Investigations Report 89–4105,

150 p.

King, K.A., Custer, T.W., and Weaver, D.A., 1994, Reproductive

success of barn swallows nesting near a selenium-contaminated lake in east Texas, USA: Environmental Pollution, v.

84, p. 53–58.

King, P.B., and Beikman, H.M., 1974a, comps., Geologic map of

the United States (exclusive of Alaska and Hawaii): U.S. Geological Survey, three sheets, scale 1:2,500,000.

———1974b, Explanatory text to accompany the geologic map of

the United States: U.S. Geological Survey Professional Paper

901, 40 p.

Knapton, J.R., Jones, W.E., and Sutphin, J.W., 1988, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the Sun River area,

west-central Montana, 1986–87: U.S. Geological Survey

Water-Resources Investigations Report 87–4244, 78 p.

Lakin, H.W., and Byers, H.G., 1941, Selenium occurrence in certain soils in the United States, with a discussion of related

topics—Sixth report: U.S. Department of Agriculture Technical Bulletin 783, 27 p.

References Cited
34 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

Lambing, J.H., Jones, W.E., and Sutphin, J.W., 1988, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the Bowdoin

National Wildlife Refuge and adjacent areas of the Milk River

Basin, northeastern Montana, 1986–87: U.S. Geological Survey Water-Resources Investigations Report 87–4243, 71 p.

Lambing, J.H., Nimick, D.A., Knapton, J.R., and Palawski, D.U.,

1994, Physical, chemical, and biological data for detailed

study of the Sun River Irrigation Project, Freezout Lake Wildlife Management Area, and Benton Lake National Wildlife

Refuge, west-central Montana, 1990–92, with selected data

for 1987–89: U.S. Geological Survey Open-File Report 94–

120, 171 p.

Lemly, A.D., 1985, Toxicology of selenium in a freshwater reservoir—Implications for environmental hazard evaluation and

safety: Ecotoxicology and Environmental Safety, v. 10, p.

314–338.

———1993, Subsurface agricultural irrigation drainage—The

need for regulation: Regulatory Toxicology and Pharmacology, v. 17, p. 157–180.

———1995, A protocol for aquatic hazard assessment of selenium: Ecotoxicology and Environmental Safety, v. 32, p.

280–288.

Lico, M.S., 1992, Detailed study of irrigation drainage in and near

wildlife management areas, west-central Nevada, 1987–90—

Part A, Water quality, sediment composition, and hydrogeochemical processes in Stillwater and Fernley Wildlife Management Areas: U.S. Geological Survey Water-Resources

Investigations Report 92–4024–A, 65 p.

Low, W.H., and Mullins, W.H., 1990, Reconnaissance investigations of water quality, bottom sediment, and biota associated

with irrigation drainage in the American Falls Reservoir area,

Idaho, 1988–89: U.S. Geological Survey Water-Resources

Investigations Report 90–4120, 78 p.

MacCoy, D.E., 1994, Physical, chemical, and biological data for

detailed study of irrigation drainage in the Klamath Basin,

California and Oregon, 1990–92: U.S. Geological Survey

Open-File Report 93–497, 168 p.

Moore, S.B., Winckel, J., Detwiler, S.J., Klasing, S.A., Gaul, P.A.,

Kanim, N.R., Kesser, B.E., DeBevec, A.B., Beardsley, K., and

Puckett, L.K., 1990, Fish and wildlife resources and agricultural drainage in the San Joaquin Valley, California: Sacramento, Calif., San Joaquin Valley Drainage Program, 2 v.

Moxon, A.L., Olson, O.E., and Searight, W.V., 1939, Selenium

in rocks, soils, and plants: South Dakota Agricultural Experiment Station Technical Bulletin, v. 2, 94 p.

Mueller, D.K., DeWeese, L.R., Garner, A.J., and Spruill, T.B.,

1991, Reconnaissance investigation of water quality, bottom

sediment, and biota associated with irrigation drainage in the

Middle Arkansas River Basin, Colorado and Kansas, 1988–

89: U.S. Geological Survey Water-Resources Investigations

Report 91–4060, 84 p.

Nebert, D.D., 1994, Design of the distributed spatial-data library

(DSDL) for the Water Resources Division, U.S. Geological

Survey: U.S. Geological Survey Open-File Report 94–327,

27 p.

Nimick, D.A., Lambing, J.H., Palawski, D.U., and Malloy, J.C.,

1996, Detailed study of selenium in soil, water, bottom sediment, and biota in the Sun River Irrigation Project, Freezout

Lake Wildlife Management Area, and Benton Lake National

Wildlife Refuge, west-central Montana, 1990–92: U.S. Geological Survey Water-Resources Investigations Report 95–

4170, 120 p.

Ohlendorf, H.M., 1989. Bioaccumulation and effects of selenium in

wildlife, in Jacobs, L.W., ed., Selenium in agriculture and the

environment: Madison, Wisc., American Society of Agronomy and Soil Science Society of America Special Publication

23, p. 133–177.

Ohlendorf, H.M., Hoffman, D.J., Saiki, M.K., and Aldrich, T.W.,

1986, Embryonic mortality and abnormalities of aquatic

birds—Apparent impact of selenium from irrigation drainwater: Science of the Total Environment, v. 52, p. 49–63.

Ohlendorf, H.M., Kilness, A.W., Simmons, J.L., Stroud, R.K.,

Hoffman, D.J., and Moore, J.F., 1988, Selenium toxicosis in

wild aquatic birds: Journal of Toxicology and Environmental

Health, v. 24, p. 67–92.

Ohlendorf, H.M., Skorupa, J.P., Saiki, M.K., and Barnum, D.A.,

1993, Food-chain transfer of trace elements to wildlife, in

Allen, R.G., and Neale, C.M.U., eds., Management of irrigation and drainage systems—Integrated perspectives: New

York, American Society of Civil Engineers, p. 596–603.

Ong, Kim, O'Brien, T.F., and Rucker, M.D., 1992, Reconnaissance

investigation of water quality, bottom sediment, and biota

associated with irrigation drainage in the middle Rio Grande

valley and Bosque del Apache National Wildlife Refuge, New

Mexico, 1988–89: U.S. Geological Survey Water-Resources

Investigations Report 91–4036, 113 p.

Owenby, J., Heim, R., Jr., Burgin, M., and Ezell, D., 1992, Climatography of the United States—Maps of annual 1961–90

normal temperature, precipitation, and degree days, in Supplement no. 3, 1961–90 normal mean annual precipitation:

Ashville, N.C., National Oceanic and Atmospheric Administration National Climatic Data Center, map 81, scale

1:5,600,000.

Parret, Charles, and Omang, R.J., 1986, Montana surface-water

resources, in U.S. Geological Survey, 1986, National water

summary 1985—Hydrologic events and surface-water

resources: U.S. Geological Survey Water-Supply Paper 2300,

p. 309–314.

Peltz, L.A., and Waddell, Bruce, 1991, Physical, chemical, and biological data for detailed study of irrigation drainage in the middle Green River Basin, Utah, 1988–89, with selected data for

1982–87: U.S. Geological Survey Open-File Report 91–530,

213 p.
REFERENCES CITED 35

Peterson, D.A., Harms, T.F., Ramirez, P., Jr., Allen, G.T., and Christenson, A.H., 1991, Reconnaissance investigation of water

quality, bottom sediment, and biota associated with irrigation

drainage in the Riverton Reclamation Project, Wyoming,

1988–89: U.S. Geological Survey Water-Resources Investigations Report 90–4187, 84 p.

Peterson, D.A., Jones, W.E., and Morton, A.G., 1988, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the Kendrick Reclamation Project area, Wyoming, 1986–87: U.S. Geological

Survey Water-Resources Investigations Report 87–4255, 57 p.

Piper, D.Z., and Isaacs, C.M., 1995, Geochemistry of minor elements in the Monterey Formation, California—Seawater

chemistry of deposition: U.S. Geological Survey Professional

Paper 1566, 41 p.

Presser, T.S., 1994a, Geologic origin and pathways of selenium

from the California coast ranges to the west-central San Joaquin Valley, in Frankenberger, W.T., Jr., and Benson, Sally,

eds., Selenium in the environment: New York, Marcel Dekker,

Inc., p. 139–155.

———1994b, “The Kesterson effect”: Environmental Management, v. 18, no. 3, p. 437–454.

Presser, T.S., Sylvester, M.A., and Low, W.H., 1994, Bioaccumulation of selenium from natural geologic sources in the Western

United States and its potential consequences: Environmental

Management, v. 18, no. 3, p. 423–436.

Radtke, D.B., Kepner, W.G., and Effertz, R.J., 1988, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the lower Colorado

River valley, Arizona, California, and Nevada, 1986–87: U.S.

Geological Survey Water-Resources Investigations Report

88–4002, 77 p.

Rea, Alan, and Cederstrand, J.R., 1994, GCIP reference data set

(GREDS) [CD–ROM]: U.S. Geological Survey Open-File

Report 94–388.

Rinella, F.A., Mullins, W.H., and Schuler, C.A., 1994, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the Owyhee and

Vale Projects, Oregon and Idaho, 1990–91: U.S. Geological

Survey Water-Resources Investigations Report 93–4156,

101 p.

Rinella, F.A., and Schuler, C.A., 1992, Reconnaissance investigation of water quality, bottom sediment, and biota associated

with irrigation drainage in the Malheur National Wildlife Refuge, Harney County, Oregon, 1988–89: U.S. Geological Survey Water-Resources Investigations Report 91–4085, 106 p.

Roddy, W.R., Greene, E.A., and Sowards, C.L., 1991, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the Bell Fourche

Reclamation Project, western South Dakota, 1988–89: U.S.

Geological Survey Water-Resources Investigations Report

90–4192, 113 p.

Rowe, T.G., Lico, M.S., Hallock, R.J., Maest, A.S., and Hoffman,

R.J., 1991, Physical, chemical, and biological data for detailed

study of irrigation drainage in and near Stillwater, Fernley, and

Humboldt Wildlife Management Areas and Carson Lake,

west-central Nevada, 1987–89: U.S. Geological Survey OpenFile Report 91–185, 199 p.

San Joaquin Valley Drainage Program, 1990, A management plan

for agricultural subsurface drainage and related problems on

the westside San Joaquin Valley: San Joaquin Valley Drainage

Program, U.S. Department of the Interior and California

Resources Agency, 183 p.

Schroeder, R.A., Palawski, D.U., and Skorupa, J.P., 1988, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the Tulare Lake

Bed area, southern San Joaquin Valley, California, 1986–87:

U.S. Geological Survey Water-Resources Investigations

Report 88–4001, 86 p.

Schroeder, R.A., Rivera, Mick, and others, 1993, Physical, chemical, and biological data for detailed study of irrigation drainage in the Salton Sea area, California, 1988–90: U.S. Geological Survey Open-File Report 93–83, 179 p.

Schruben, P.G., Arndt, R.E., and Bawiec, W.J., 1994, Geology of

the conterminous United States at 1:2,500,000 scale—A digital representation of the 1974 P.B. King and H.M. Beikman

map [CD–ROM]: U.S. Geological Survey Digital Data Series

DDS–11.

See, R.B., Naftz, D.L., Peterson, D.A., Crock, J.G., Erdman, J.A.,

Severson, R.C., Ramirez, P., Jr., and Armstrong, J.A., 1992,

Detailed study of selenium in soil, representative plants, water,

bottom sediment, and biota in the Kendrick Reclamation

Project area, Wyoming, 1988–90: U.S. Geological Survey

Water-Resources Investigations Report 91–4131, 142 p.

See, R.B., Peterson, D.A., and Ramirez, P., Jr., 1992, Physical,

chemical, and biological data for detailed study of irrigation

drainage in the Kendrick Reclamation Project area, Wyoming,

1988–90: U.S. Geological Survey Open-File Report 91–533,

272 p.

Seiler, R.L, 1995, Prediction of areas where irrigation drainage may

induce selenium contamination of water: Journal of Environmental Quality, v. 24, no. 5, p. 973–979.

———1996, Synthesis of data from studies by the National Irrigation Water Quality Program: Water Resources Bulletin, v. 32,

no. 6, p. 1233–1245.

Seiler, R.L., Ekechukwu, G.A., and Hallock, R.J., 1993, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in and near Humboldt

Wildlife Management Area, Churchill and Pershing Counties,

Nevada, 1990–91: U.S. Geological Survey Water-Resources

Investigations Report 93–4072, 115 p.

References Cited
36 Areas Susceptible to Irrigation-Induced Selenium Contamination of Water and Biota in the Western United States

Setmire, J.G., Schroeder, R.A., Densmore, J.N., Goodbred, S.L.,

Audet, D.J., and Radke, W.R., 1993, Detailed study of water

quality, bottom sediment, and biota associated with irrigation

drainage in the Salton Sea area, California, 1988–90: U.S.

Geological Survey Water-Resources Investigations Report

93–4014, 102 p.

Setmire, J.G., Wolfe, J.C., and Stroud, R.K., 1990, Reconnaissance

investigation of water quality, bottom sediment, and biota

associated with irrigation drainage in the Salton Sea area, California, 1986–87: U.S. Geological Survey Water-Resources

Investigations Report 89–4102, 68 p.

Skorupa, J.P., 1998, Selenium poisoning of fish and wildlife—

Lessons from twelve real-world examples, in Frankenberger,

W.T., Jr., and Engberg, R.A., Environmental chemistry of selenium: New York, Marcel Dekker, p. 315–354.

Skorupa, J.P., and Ohlendorf, H.M., 1991, Contaminants in drainage water and avian risk thresholds, in Dinar, Ariel, and

Zilberman, David, eds., The economics and management of

water and drainage in agriculture: Boston, Kluwer Academic

Publishers, p. 345–368.

Sorenson, S.K., and Schwarzbach, S.E., 1991, Reconnaissance

investigation of water quality, bottom sediment, and biota

associated with irrigation drainage in the Klamath Basin,

California and Oregon, 1988–89: U.S. Geological Survey

Water-Resources Investigations Report 90–4203, 64 p.

Stephens, D.W., Waddell, Bruce, BuBois, Kristi, and Peterson,

Elise, 1997, Field screening of water quality, bottom sediment,

and biota associated with the Emery and Scofield Project

areas, central Utah, 1994, U.S. Geological Survey WaterResources Investigations Report 96–4298, 39 p.

Stephens, D.W., Waddell, Bruce, and Miller, J.B., 1988, Reconnaissance investigation of water quality, bottom sediment, and

biota associated with irrigation drainage in the middle Green

River Basin, Utah, 1986–87: U.S. Geological Survey WaterResources Investigations Report 88–4011, 70 p.

Stephens, D.W., Waddell, Bruce, Peltz, L.A., and Miller, J.B., 1992,

Detailed study of selenium and selected elements in water,

bottom sediment, and biota associated with irrigation drainage

in the middle Green River Basin, Utah, 1988–90: U.S. Geological Survey Water-Resources Investigations Report 92–

4084, 164 p.

Sylvester, M.A., Deason, J.P., Feltz, H.R., and Engberg, R.A., 1988,

Preliminary results of the Department of the Interior’s irrigation-drainage studies, in Hay, D.R., ed., Planning now for irrigation and drainage—Proceedings of the American Society of

Civil Engineers Irrigation Division meeting, July 18–21,

1988, Lincoln, Neb.: [Lincoln, Neb.], American Society of

Civil Engineers, p. 655–677.

Tanji, Kenneth, Läuchli, André, and Meyer, Jewell, 1986, Selenium

in the San Joaquin Valley: Environment, v. 28, no. 6, p. 6–39.

Thodal, C.E., and Tuttle, P.L., 1996, Field screening of water quality, bottom sediment, and biota associated with irrigation

drainage in and near Walker River Indian Reservation,

Nevada, 1994–95: U.S. Geological Survey Water-Resources

Investigations Report 96–4214, 39 p.

Thomas, C.L., Lusk, J.D., Bristol, R.S., Wilson, R.M., and Shineman, A.R., 1997, Physical, chemical, and biological data for

detailed study of irrigation drainage in the San Juan River

area, New Mexico, 1993–94, with supplemental data, 1991–

95: U.S. Geological Survey Open-File Report 97–249, 227 p.

Tidball, R.R., Severson, R.C., Presser, T.S., and Swain, W.C., 1991,

Selenium sources in the Diablo Range, western Fresno

County, California, in Severson, R.C., Fisher, S.E., Jr., and

Gough, L.P., eds., Proceedings of the 1990 Billings Land

Reclamation Symposium on Selenium in Arid and Semiarid

Environments, Western United States: U.S. Geological Survey

Circular 1064, p. 107–114.

Trelease, S.F., and Beath, O.A., 1949, Selenium, its geological

occurrence and its biological effects in relation to botany,

chemistry, agriculture, nutrition, and medicine: Burlington,

Vt., Champlain Printers, 292 p.

U.S. Environmental Protection Agency, 1987, Ambient water-quality criteria for selenium—1987: Washington, D.C., Report

EPA–440/5–87–006, 121 p.

U.S. Fish and Wildlife Service, 1988, National Wildlife Refuges—

A visitor’s guide [pamphlet]: Washington, D.C., U.S. Government Printing Office, GPO 193–006.

Wells, F.C., Jackson, G.A., and Rogers, W.J., 1988, Reconnaissance

investigation of water quality, bottom sediment, and biota

associated with irrigation drainage in the lower Rio Grande

valley and Laguna Atascosa National Wildlife Refuge, Texas,

1986–87: U.S. Geological Survey Water-Resources Investigations Report 87–4277, 89 p.

Willden, Ronald, and Speed, R.C., 1974, Geology and mineral

deposits of Churchill County, Nevada: Nevada Bureau of

Mines and Geology Bulletin 83, 95 p.
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Seiler and others—AREAS SUSCEPTIBLE TO IRRIGATION-INDUCED SELENIUM CONTAMINATION, WESTERN UNITED STATES—U.S. Geological Survey Circular 1180

The San Juan River in northwestern New Mexico, like other rivers in the Western United States, provides water for

recreation, wildlife, and agricultural use. Photograph by Carole L. Thomas, U.S. Geological Survey, 1993