EPA-660/3-75-018
MAY 1975
Ecological Research Series
Ground-Water Pollution Problems in the
Northwestern United States
W.
LU
PRtf
National Environmental Research Center
Office of Research and Development
U^. Environmental Protection Agency
Corvallis, Oregon 97330
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development,
U.S. Environmental Protection Agency, have been grouped into
five series. These five broad categories were established to
facilitate further development and application of environmental
technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in
related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ECOLOGICAL RESEARCH STUDIES
series. This series describes research on the effects of pollution
on humans, plant and animal "species, and materials. Problems are
assessed for their long- and short-term influences. Investigations
include formation, transport, and pathway studies to determine the
fate of pollutants and their effects. This work provides the technical
basis for setting standards to minimize undesirable changes in living
organisms in the aquatic, terrestrial and atmospheric environments.
EPA REVIEW NOTICE
This report has been reviewed by the Office of Research and
Development, EPA, and approved for publication. Approval does
not signify that the contents necessarily reflect the views and
policies of the Environmental Protection Agency, nor does mention
of trade names or commercial products constitute endorsement or
recommendation for use.
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EPA-660/3-75-018
MAY 1975
GROUND-WATER POLLUTION PROBLEMS
IN THE NORTHWESTERN UNITED STATES
by
Frits van der Leeden, Lawrence A. Cerrillo, and David W. Miller
Contract No. 68-03-0298
Program Element 1BA024
ROAP/Task No. 21 AIO-005
Project Officer
Marion R. Scalf
Robert S. Kerr Environmental Research Laboratory
National Environmental Research Center
Ada, Oklahoma
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330
For Sale by the National Technical Information Service
U.S. Department of Commerce, Springfield, VA 22151
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ABSTRACT
An evaluation of ground-water contamination problems has
been carried out in six states in the northwest: Colorado,
Idaho, Montana, Oregon, Washington and Wyoming. Ground-
water supplies 12 percent of the total water withdrawn in
the region, with the major pumpage in Colorado and Idaho.
Industrial and agricultural growth and development of new
energy sources will cause a sharp increase in ground-water
use over the next 30 years.
Natural ground-water quality varies widely. Saline ground
water underlies more than half of Colorado, Montana and
Wyoming. In the mountainous areas, and in the more humid
sections of Idaho, Washington and Oregon, the quality of
ground water is generally good to excellent. The most com-
mon natural ground-water quality problems, other than high
salinity, are excessive hardness, iron, manganese, and
fluoride. Principal sources of man-caused ground-water
quality problems in the approximate order of severity are:
discharge of effluent from septic tanks and sewage treatment
plants, irrigation return flow, dryland farming, abandoned
oil wells, shallow disposal wells, unlined surface impound-
ments, mine tailings and mine drainage, municipal and indus-
trial landfills, and radioactive waste disposal. Other
sources that appear to be of less importance but still must
be considered include: spills and leaks, application of
fertilizers and pesticides, feedlots, and salt-water intru-
sion.
The findings of the investigation indicate that, with the
exception of radioactive waste disposal, few cases of ground-
water pollution have been investigated in detail. There is
a need for baseline water-quality data and systematic evalu-
ation of overall ground-water conditions, especially in
urban zones, in areas of petroleum exploration and develop-
ment, and at locations of mining and industrial activity.
This report was submitted in fulfillment of Contract
68-03-0298 by Geraghty & Miller, Inc., under the sponsorship
of the U. S. Environmental Protection Agency. Work was com-
pleted as of October 1974.
ii
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CONTENTS
Page
Abstract ii
List of Figures vi
List of Tables x
Acknowledgements xiv
Sections
I Conclusions 1
II Recommendations 5
III Introduction 6
Use of Ground Water 7
Trends in Ground-Water Use 14
References Cited 17
IV Description of Project Area 19
Physiography 19
Population 22
Climate 24
Geology and Ground-Water Resources 24
Colorado 28
Idaho 42
Montana 57
Oregon 69
Washington 75
Wyoming 83
References Cited 95
V Natural Ground Water Quality 107
Introduction 107
Principal Problems of Natural Ground-
Water Quality 107
Total Dissolved Solids 108
Iron and Manganese 115
Fluoride 117
Trace Metals 119
Radionuclides 121
Arsenic 123
111
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V Natural Ground-Water Quality (continued)
Thermal Springs 123
Base-Line Ground-Water Quality Conditions 131
Colorado 133
Idaho 144
Montana 151
Oregon 169
Washington 186
Wyoming 197
References Cited 208
VI Sources of Ground-Water Contamination 222
Introduction 222
Movement of Waste Fluids 222
Sources of Ground-Water Contamination 225
Types of Contaminants 230
Health Hazards 231
Control and Removal of Contaminants 231
Monitoring Ground-Water Quality 234
Septic Systems 235
Sewage Treatment Plant Discharge 245
Irrigation Return Flow 247
Dryland Farming 255
Abandoned Oil Wells and Test Wells 260
Brine Injection 264
Disposal Wells 267
Surface Impoundments 273
Mining 280
Landfills 293
Radioactive Waste 295
Spills and Leaks 312
Fertilizers and Pesticides 315
Feedlots 319
Salt-Water Intrusion 323
Highway Deicing Salts 324
Mass Burial of Livestock 324
References Cited 327
IV
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VII Research and Other Needs
Trends in Ground-Water Pollution
General Research Needs
Specific Needs
VIII Appendix A - Glossary of Terms
Appendix B - Water Quality Standards
Appendix C - Constants and Conversion Factors
v
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FIGURES
No. Page
1. Comparison of Ground-Water Use to Surface-
Water Use in 1970 12
2. Use of Ground Water in 1970 13
3. Ground-Water Regions and Major Aquifers 20
4. Geology of the Northwestern States 23
5. Mean Annual Precipitation 26
6. Mean Annual Runoff 27
7. Colorado - Major Ground-Water Areas 29
8. Colorado - Major Aquifers and Well Yields 30
9. Idaho - Major Aquifers and Depths of Wells 46
10. Idaho - Range in Yields of Wells 47
11. Idaho - Ground-Water Areas of the Snake River
Basin 50
12. Montana - Bedrock Geology, Major Rivers, and
Pre-Glacial Drainage Courses 60
13. Montana - Ground-Water Potential of Major Un-
consolidated Aquifers 61
14. Oregon - Major Drainage and Physiographic
Features 70
15. Oregon - Availability of Ground Water 72
16. Washington - Ground-Water Provinces and Major
Aquifers 77
17. Washington - Well Yields 78
18. Wyoming - Major Drainage Features and Alluvial
Aquifers 85
19. Wyoming - Major Tertiary Sandstone Aquifers 86
VI
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FIGURES (Continued)
No. Page
20. Depth to Ground Water Containing More Than
1,000 mg/1 Dissolved Solids 109
21. Quality of Shallowest Mineralized Ground Water
in the Northwest 110
22. Hardness of Ground Water in the Northwest 114
23. Fluoride Content of Ground Water in the
Northwest 118
24. Fluoride Concentration of Ground Water in the
Confined Aquifer, San Luis Valley, Colorado 120
25. Arsenic in Ground Water of Lane County, Oregon 124
26. Distribution of Thermal Springs in the Northwest 125
27. Location of Major Thermal Springs in Western
Colorado 127
28. Colorado - Depth to Ground Water Containing More
Than 1,000 mg/1 Dissolved Solids 134
29- Idaho - Conductivity of Ground Water in the
Snake Plain Aquifer 150
30. Montana - Depth to Ground Water Containing More
Than 1,000 mg/1 Dissolved Solids 153
31. Oregon - Iron and Arsenic in Ground Water of the
Willamette Basin 183
32. Oregon - Upward Migration of Saline Ground Water
in the Tualatin Valley 184
33. Washington - Dissolved Solids and Iron in Ground
Water 194
34. Wyoming - Depth to Ground Water Containing More
Than 1,000 mg/1 Dissolved Solids 204
35. Movement of Contaminated Ground Water Beneath
Leaky Disposal Pond 224
VII
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FIGURES (Continued)
No. Page
36. Movement of Contaminated Surface Water to a
Pumping Water Well 226
37. Movement of Deep Saline Ground Water into a
Fresh-Water Aquifer by Means of an Improperly
Sealed Open Hole 227
38. Disposal of Household Wastes Through a Conven-
tional Septic Tank and Soil Absorption System 237
39. A Cross-Section of a Typical Mountain Setting
for Domestic Wells and Septic Systems on
Thin Soils and a Fractured Rock Aquifer 242
40. Distribution of Irrigated Areas in the Northwest 248
41. Cross Section of Grand Valley of Colorado Illus-
trating Salt Pickup from Irrigated Lands 252
42. Idealized Block Diagram of Part of the Arkansas
River Valley Illustrating Variable Ground-
Water Quality 254
43. Cross-Section of a Typical Saline-Seep Area in
Northern Montana 256
44. Dryland Farming and Area of Potential Saline-
Seep Development in Montana 259
45. Principal Oil and Gas Fields in the Northwest 262
46. Schematic Diagram of a Typical Sewage Disposal
Well in Lava Terrane 270
47. Potential Contamination of Ground Water from
Perched Water Entering Uncased Water Well 271
48. Area of Ground-Water Contamination at Rocky
Mountain Arsenal, Denver, Colorado 276
49- Diagrammatic Cross-Section of Ground-Water Pol-
lution Caused by Settling Ponds and Mine
Tailings in Northern Idaho 278
50. Areas of Coal Reserves and Strippable Reserves 285
Vlll
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FIGURES (Continued)
No.
51.
52.
53.
54,
55,
56
57
58,
59,
60,
Areas Underlain by Oil Shale
Extent of Area of Contaminated Ground Water
Caused by Wood Waste Leachate Near Turner,
Oregon
Extent of Area of Contaminated Ground Water at
Keizer, Oregon
National Reactor Testing Station, Idaho. Cross
Section of TRA Disposal Pond Area Showing
Perched Waste Water Zone
National Reactor Testing Station, Idaho. Tri-
tium Content in Perched Waste Water Below
the Test Reactor Area
National Reactor Testing Station, Idaho. Dis-
tribution of Tritium and Chromium in the
Snake River Plain Aquifer at the ICPP and
TRA Facilities
Hanford Reservation, Washington. Cross-Section
of a Typical Crib
Hanford Reservation, Washington. Location of
Plant Facilities and Observation Wells
Hanford Reservation, Washington. Tritium Con-
centrations in Ground Water
Hanford Reservation, Washington. Nitrate Con-
centrations in Ground Water
Page
289
296
297
301
302
303
306
308
310
311
IX
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TABLES
No.
1. Estimated Use of Water in the Northwest United
States in 1970 8
2. Ground Water Use, 1965-70 15
3. Population Characteristics 25
4. Colorado. Use of Water Wells in South Platte
River Basin 33
5. Idaho. Annual Withdrawal and Use of Ground Water
in Major Drainage Basins 43
6. Montana. Use of Water Wells, 1967 62
7. Wyoming. Well Depth, Yield and Water Quality
of Aquifers 87
8. Tabulation of Selected Chemical Analyses of Shal-
low Saline Ground Water in the Northwest 112
9. Household Damages Caused by Use of Mineralized
Surface and Ground Water in 1970 116
10. Quality of Thermal Spring Water in Western
Colorado 128
11. Tabulation of Selected Chemical Analyses of
Thermal Ground Water in Colorado, Idaho and
Wyoming 129
12. Discharge, Dissolved Solids Load, and Dissolved
Solids Concentration of Thermal Springs in
Western Colorado 132
13. Tabulation of Selected Chemical Analyses of
Ground Water in Colorado 135
14. Quality of Ground Water of Some Municipal Supply
Systems in the South Platte and Arkansas
River Valleys, Colorado, 1971 141
15, Tabulation of Selected Chemical Analyses of
Ground Water in Idaho 145
x
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TABLES (Continued)
No. Page
16. Tabulation of Selected Chemical Analyses of
Ground Water in Montana 154
17. Tabulation of Selected Chemical Analyses of
Ground Water in Oregon 170
18. Tabulation of Selected Chemical Analyses of
Ground Water in Washington 187
19. Tabulation of Selected Chemical Analyses of
Ground Water in Wyoming 198
20. Principal Sources of Ground-Water Contamination
and Their Relative Impact in the Northwest 229
21. Health Hazards Attributable to Ground-Water
Contamination 232
22. Incidence of Waterborne Disease in the U. S.,
1946-70, due to Source Contamination: Ground
Water (Untreated) 233
23. Estimated Population Served by Septic Tanks in
1968 236
24. Normal Range of Mineral Pickup in Domestic
Sewage 239
25. Movement of Bacteria Through Porous Media 241
26. Number of Sewage Treatment Plants and Population
Served in 1968 246
27. Irrigated Land Areas in 1970 249
28. Land Areas Affected by Salinity in 1960 251
29- Chemical Analyses of Saline Seep Water from the
Fort Benton Area, Montana 258
30. Crude Oil Production in the Northwest 261
31. Oil and Gas Drilling Activity, 1971-72 263
32. Comparison of Dissolved Solids in Sea Water and
Oil Field Brine 266
XI
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TABLES (Continued)
No.
33. Average Composition of Liquid Waste Effluent
Discharged at Idaho Chemical Processing
Plant Disposal Well 269
34. Number of Drain Wells in the Snake River Plain 270
35. Major Mineral Production in the Northwest Exclu-
sive of Petroleum and Related Products 281
36. Fish and Wildlife Habitat Adversely Affected by
Strip and Surface Mining in the Northwest
as of January 1, 1967 282
37. Concentrations of Selected Trace Elements in
Some Montana and Wyoming Coal Beds 283
38. Land Disturbed by Strip and Surface Mining in
the Northwest as of January 1, 1965 284
39. Strippable Resources and Reserves of Coal in
the Northwest as of January 1, 1968 287
40. Abandoned and Inactive Underground Mines in
the Northwest as of 1966 288
41. Longer-Lived Nuclides Being Discharged at the
Test Reactor Area Facility on the National
Reactor Testing Station Site 299
42. Consumption of Commercial Fertilizers in 1970 316
43. Chemical Analyses of Ground Water Beneath
Feedlots and Adjacent Irrigated Fields in
the South Platte Valley of Colorado 317
44. Some of the Constituents of Waste from a
1,000 Pound Bovine 320
45. Number and Capacity of Feedlots in the
Northwest 321
46. Use of Deicing Salt (Sodium Chloride) in the
Northwest in the Winter of 1966-67 325
XII
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TABLES (Continued)
No. Page
47. Principal Sources of Ground-Water Contamination
and the Priority for Additional Research and
Control in the Northwest 347
48. U. S. Public Health Service Chemical Standards
of Drinking Water, 1962 359
Xlll
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ACKNOWLEDGEMENTS
This report would not have been possible without the informa-
tion received from numerous organizations and individuals.
Personnel from federal, state, county, and municipal govern-
mental agencies contributed data on ground-water conditions,
natural ground-water quality, incidents of pollution and
trends in water use. The U. S. Geological Survey, Water Re-
sources Division offices in the various states made avail-
able reports and general information on ground-water re-
sources in the region.
Special appreciation is extended to Mr. Maxwell Botz, Mon-
tana Department of Health; Mr. Keith Higginson, Idaho De-
partment of Water Resources; Mr. Robert Russell, Washington
Department of Ecology; and Mr. Leonard F. Konikow, U. S.
Geological Survey, Denver, for their review of and comments
on the data presented.
Mr. Russell W. Fitch of EPA office for Region VIII, Mr. Jack
E. Sceva of EPA office for Region X, and Mr. Kenneth W. Webb
of the Colorado Department of Public Health supplied informa-
tion on existing studies and suggested sources of additional
data. The support and guidance provided on the various
phases of the work by Mr. Marion R. Scalf, Project Officer,
Robert S. Kerr Environmental Research Laboratory, Ada, Okla-
homa, are gratefully acknowledged.
The authors of this report are hydrogeologists with the firm
of Geraghty & Miller, Inc., Port Washington, New York, and
are Associate, Staff Hydrogeologist and Vice President, re-
spectively- Special appreciation is accorded to other staff
members, particularly to Mrs. Elaine LaBella for bibliograph-
ical research, data reduction, and preparation of tabula-
tions; Mrs. Nola P- Gillies for advice on key sources of in-
formation; Mr. David K. Shaw for preparation of illustra-
tions; and Mrs. Marie Edmonds and Mrs. Alice Marsala for
preparation of the manuscript.
xiv
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SECTION I
CONCLUSIONS
1. Total use of ground water in the six-state region in
1970 was 25.8 million cu m/d (6.8 billion gpd) of which
70 percent was for irrigation.
2. Ground water supplied 33 percent of public, 73 percent
of rural, 18 percent of industrial, and 10 percent of
irrigation requirements.
3. A sharp increase in ground-water use is expected in the
next thirty years due to rapid industrial and agricul-
tural growth, and the development of new energy sources
from coal and perhaps oil shale deposits.
4. The major unconsolidated aquifers are in the Willamette
River basin, the Puget Sound Lowland, the San Luis Val-
ley, the South Platte and Arkansas River basins, the
Spokane Valley-Rathdrum Prairie and on the Colorado High
Plains.
5. Principal consolidated aquifers are sandstones; lime-
stones and dolomites; and the basalt rocks of the
Columbia Plateau and the Snake River Plain.
6. The natural quality of ground water varies widely due to
differences in geologic and climatic conditions. More
than half of the areas of the states of Colorado, Mon-
tana, and Wyoming are underlain by aquifers containing
saline ground water. In the more humid states of Idaho,
Washington, and Oregon, the natural ground-water quality
is generally good to excellent.
7. The most common natural water-quality problems in fresh-
water aquifers are high hardness, excessive iron and
manganese content, and high concentrations of fluoride.
8. The most significant source of ground-water contamina-
tion is the discharge of sewage from septic tank systems,
Three million people, equivalent to one-third of the
area's total population, are served by individual septic
systems. Mountain home sites in crystalline rock areas
with thin soil cover and on-site water wells are partic-
ularly subject to pollution of drinking water supplies
from septic effluent. High septic tank density in some
urban and suburban sections has led to regional problems,
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9. Discharge of treated or partially treated effluent from
sewage treatment plants to rivers and streams is a po-
tential hazard to ground-water quality, particularly in
semi-arid regions. Shallow aquifers in the Plains
states are especially vulnerable where unconsolidated
valley aquifers are in hydraulic connection with a
river, and pumpage from wells induces surface water to
enter the aquifer.
10. Irrigation return flow is another pressing pollution
problem. A total of 6.3 million ha (15.5 million
acres), representing 4 percent of the project area, is
under irrigation. As of 1960, about 840,000 ha (2 mil-
lion acres) were affected by salinity. Nearly 50 per-
cent of this area was in Colorado.
11. Dryland farming in geologically unsuitable areas has
caused the formation of extensive saline seeps on the
northern Great Plains. The most serious problems are
found in Montana, with over 32,000 ha (80,000 acres)
having been affected as of 1971. Since then, an esti-
mated additional 40,000 to 60,000 ha (100,000 to 150,000
acres) of crop land has been lost to saline seeps. A
change in farming practices may be needed to control
this type of degradation.
12. Well construction and abandonment procedures connected
with oil and gas development are potential sources of
ground-water contamination in Colorado, Montana, and
Wyoming. Leaky casings, improperly cemented wells, and
unplugged or inadequately plugged abandoned holes allow
poor-quality water to leak into fresh-water aquifers.
Each year, the oil industry drills several thousand ex-
ploratory and development wells, of which over a thou-
sand are plugged and abandoned. Legislation regarding
the sealing and abandonment of wells and test holes
exists, but enforcement is lacking in many areas.
13. Brine associated with oil is usually returned to the
producing formation via more than 3,000 injection wells
in the states of Colorado, Montana and Wyoming. The
danger lies in failure of the wells or leakage through
confining zones, which would cause brine to flow into
fresh-water zones. There is practically no documenta-
tion concerning ground-water contamination caused by
injection of oil-field brines.
14. A few deep wells have been drilled for disposal of in-
dustrial liquid wastes and an estimated 8,000 shallow
wells are used for disposal of domestic and agricultural
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waste fluids. The latter pose the greater threat to
ground-water quality because they typically discharge
into the unsaturated zones of formations containing
fresh water. Despite the large volume of waste being
discharged in this manner, few serious incidents of
contamination have been reported.
15. Surface impoundments used to treat, handle, or store
liquid wastes and sludges are leaking large quantities
of contaminants to ground water. The number of lagoons,
pits, and basins is expected to increase sharply as in-
dustries change over from direct surface-water dis-
charge to land treatment of wastes.
16. Every state in the project area has waters adversely
affected by leachate from tailings piles and drainage
from strip, surface, and underground mines. The indus-
try is expected to grow rapidly under the federal gov-
ernment's drive for self-sufficiency in energy. Large-
scale surface mining of coal on the Great Plains> mining
of oil shale in Colorado and Wyoming, including new
methods of removing minerals (such as underground coal
gasification), pose tremendous problems to ground-water
quality protection.
17. Industrial and municipal landfills are not considered a
problem in the arid or semi-arid portions of the region,
since little or no leachate is produced. In humid sec-
tions, leachate has been detected at many municipal
landfills. Land disposal of wood wastes in Montana and
Oregon has contaminated ground and surface waters with
phenols and tannic acid.
18. Millions of cubic meters of low and intermediate level
radioactive waste fluids have been disposed of in ponds
or cribs or injected into wells at the NETS and Hanford
sites. Movement of pollutants is closely watched by
the U. S. Geological Survey, using hundreds of observa-
tion wells. These waste-disposal monitoring programs
are considered to be among the most closely studied
cases of ground-water contamination in the nation.
Large plumes of contaminated ground water are present
at both sites. However, severe contamination is con-
tained within the sites, and the degree of pollution
elsewhere is below detection limits. Forecasts for
various plumes are for gradual growth but reduced con-
centrations as a result of dilution and dispersion.
19. Spills and leaks of hazardous and non-hazardous liquids
on and below the land surface are numerous. The fluids
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most frequently spilled or leaked are petroleum products
that are in transport or storage. Cases of ground-water
contamination by gasoline spills or leaks have been
documented in all six states.
20. There is little documentation regarding ground-water
pollution caused by application of fertilizers or pesti-
cides. Even in areas of heavy fertilizer use and where
there is a high incidence of nitrate contamination, the
degree of correlation between reported cases and amount
of fertilizer applied is unknown. Most cases of pesti-
cide contamination of ground water appear related to
accidental spills in the vicinity of a well or irriga-
tion canal.
21. There are over 2,400 feedlots in the northwest with
capacities ranging from less than 1,000 to over 30,000
cattle. Documented cases of ground-water pollution due
to feedlot leachate are rare, but the problem is under
study by several federal and state agencies.
22. Few cases of sea-water intrusion occur in the northwest,
and it has not been a major problem. Upward migration
of saline water in inland areas is documented in a few
areas, but no actual cases of contamination of well sup-
plies are known.
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SECTION II
RECOMMENDATIONS
1. Promote a greater appreciation of the increasing im-
portance of ground water and the need for protection of
ground-water quality on a national and regional basis
through educational and informational dissemination
programs.
2. Increase budgetary allocations to regulatory agencies
for inventorying ground-water resources, assessing and
controlling ground-water pollution, and enforcing ex-
isting regulations.
3. Develop more effective methods for inventorying exist-
ing and potential sources of ground-water contamination
on a state-wide basis.
4. Expand the monitoring of suspected sources of ground-
water contamination that might endanger drinking water
supplies.
5. Expand the standard analyses of ground water to include
a wider variety of inorganic and organic compounds.
6. Conduct additional research to develop better scientif-
ic tools to delineate the areal extent, characteristics,
and fate of pollutants in aquifers.
7. Conduct basic research into economic containment and re-
moval of various types of pollutants in aquifers.
8. Conduct further research in model simulation of stream-
aquifer systems as a water-quality management tool.
9. Develop a sound scientific basis for protection of
fresh-water aquifers from pollution through control of
land use and ground-water diversion, taking into ac-
count geologic, hydrologic, and other environmentaJ.
considerations.
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SECTION III
INTRODUCTION
The current use of fresh water in the United States for all
purposes except the generation of hydroelectric power is
about 1,140 cu hm/d or 300 bgd. D Most of this water is
supplied by rivers and streams, but in recent decades ground
water pumped from wells has begun to play a more significant
role in water supply, so that ground-water resources now
furnish one-fifth of the nation's fresh-water needs and un-
doubtedly will provide an even larger portion by 1980, when
the national water requirement will be about 2,280 cu hm/d
(600 bgd). The widespread availability of ground water and
its desirable properties, such as clarity, bacterial purity,
and generally consistent temperature and chemical quality,
have led to the present day expansion of water-well systems
in the nation. Economics and land use are other factors
favoring ground-water development. More and more public
water-supply systems, industries, and commercial establish-
ments, especially in densely populated regions, can no long-
er obtain the large tracts of land that are required for
construction of new surface-water reservoirs.
Management and protection of the ground-water resources is
of the utmost importance. Whereas pollution of surface-
water supplies is readily detected and often quickly cor-
rected, pollution of ground water is often not detected un-
til a considerable part of an aquifer system has been ad-
versely affected. Once an aquifer is polluted, it takes a
very long time and great financial expenditure to alleviate
the problem. Often the damage cannot be undone and the wa-
ter source has to be abandoned. For these reasons laws and
regulations to protect ground-water reservoirs must be
adopted. National and state-wide measures to control the
quality of ground water are needed, and recommendations to
this effect have been made by federal, state and private or-
ganizations, including the National Water Commission. 2,3,4)
Prior to devising such control measures, a full understand-
ing of natural ground-water quality and ground-water pollu-
tion problems existing in the various regions of the nation
is needed. The Environmental Protection Agency has under-
taken the task of gathering this information, and reports
dealing with ground-water pollution have been issued for the
Southwestern States, the South-Central States, and the North-
eastern States. 5,6,7)
This report deals with ground-water pollution problems in
the northwestern United States, a region that includes the
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states of Colorado, Idaho, Montana, Oregon, Washington and
Wyoming. The report is intended to give an overview of
ground-water conditions in the six states and to describe
and identify natural and man-made causes of ground-water
pollution. It also assesses the problems and trends in
ground-water quality and recommends research and control
mechanisms to protect ground-water quality.
USE OF GROUND WATER
In 1970, the total fresh ground-water withdrawal in the na-
tion was 227 cu hm/d (68 bgd), equivalent to 21 percent of
all fresh water withdrawn. 1) Surface and ground-water
withdrawals for public, rural, self-supplied industrial, and
irrigation use within the six states of the project area are
given on Table 1 and on Figures 1 and 2. As shown on Figure
1, all Northwest states are heavily dependent on surface wa-
ter, and ground-water usage ranges from 4 to 15 percent of
all fresh water withdrawn. Within the project area, ground-
water usage was about 25.8 cu hm/d (6.8 bgd), equivalent to
12 percent of the total water use, well below the national
average of 21 percent.
Public water-supply systems in the project area used a total
of 6.8 cu hm/d (1.8 bgd) of water. One-third of this water
was supplied from wells. The large cities of Denver, Port-
land and Seattle rely totally on surface-water supplies. 8)
Tacoma obtains some 6 percent of its water supply from
ground water. Spokane is the only large city in the project
area that entirely depends on ground water. In 1962 this
city obtained 257,000 cu m/d or 68 mgd of ground water from
19 wells. 8)
In the mountain areas, municipalities generally depend on
surface water for supply, but numerous community water sys-
tems, especially in Montana, Wyoming and Colorado, depend
entirely on ground water. For example, in Montana, of a
total of 173 municipalities, 150 use ground water for sup-
ply. 9) In Colorado, of a total of 244 water-supply sys-
tems, 135 depend entirely on water from wells, and 29 other
systems use a combination of surface and ground water. 10)
Rural water supplies are heavily dependent on ground water.
This water is used for domestic consumption and cattle
watering. Seventy-three percent of all rural water use is
derived from ground water.
Industrial water, exclusive of water used for power genera-
tion, is mostly derived from surface-water sources. How-
ever, 18 percent of all water used by industry is pumped
-------
Table 1. ESTIMATED USE OF WATER IN THE NORTHWEST UNITED STATES IN 1970.
Public Supply Rural Supply a) Industrial ")
State 1,
COLORADO
Ground water
Surface water
Total:
Percent of total
that is ground water
IDAHO
Ground water
Surface water
Total:
Percent of total
that is ground water
MONTANA
Ground water
Surface water
Total:
000 m3/d
299
1,173
1,472
20
363
57
420
86
98
322
420
mgd
79
310
389
96
15
111
26
85
111
I,000m3/d
110
61
171
65
121
53
174
70
98
64
162
mgd
29
16
45
32
14
46
26
17
43
I,000m3/d
208
492
700
30
1,287
416
1,703
76
129
454
583
mgd
55
130
185
340
110
450
34
120
154
Percent of total
that is ground water
23
60
22
a) Domestic and livestock
b) Saline water and water used for thermoelectric power excluded.
-------
Table 1 (continued)
State 1
OREGON
Ground water
Surface water
Total:
Percent of total
that is ground water
WASHINGTON
G round water
Surface water
Total:
Percent of total
that is ground water
WYOMING
Ground water
Surface water
Total:
Percent of total
that is ground water
GRAND TOTAL
Ground water
Surface water
Total:
. ESTIMATED USE OF WATER IN THE NORTHWEST UNITED
STATES IN 1970. }>
Public Supply Rural Supply a^ Industrial '
, 000 m3/d mgd 1
254
606
860
1,098
2,309
3,407
91
95
186
2,203
4,561
6,764
67
160
227
30
290
610
900
32
24
25
49
49
582
1,205
1,787
,000 m3/d
606
125
731
83
182
53
235
77
38
61
99
38
1,155
416
1,571
mgd
160
33
193
48
14
62
10
16
26
305
110
415
I,000m3/d
416
9,804
10,220
4
568
1,552
2,120
27
254
76
330
77
2,862
12,795
15,657
mgd
110
2,590
2,700
150
410
560
67
20
87
756
3,380
4,136
Percent of grand total
that is ground water
33
73
18
-------
Table 1 (continued). ESTIMATED USE OF WATER IN THE NORTHWEST UNITED
STATES IN 1970. ^
Irrigation Total
State
COLORADO
Ground water
Surface water
Total:
I,000m3/d
7,192
41,640
48,832
mgd
1,900
11,000
12,900
l,000mj/d
7,809
43,366
51,175
mgd
2,063
11,456
13,519
Percent of total
that is ground water 15 15
IDAHO
Ground water 7,949 2,100 9,720 2,568
Surface water 49,210 13,000 49,736 13,139
Total: 57,159 15,100 59,456 15,707
Percent of total
that is ground water 14 15
MONTANA
Ground water 238 63 564 149
Surface water 28,769 7,600 29,609 7,822
Total: 29,007 7,663 30,173 7,971
Percent of tota!
that is ground water 1 2
10
-------
Table 1 (continued). ESTIMATED USE OF WATER IN THE NORTHWEST UNITED
STATES IN 1970. ])
Irrigation Total
State
OREGON
Ground water
Surface water
Total:
l,OOOmVd
2,385
15,899
18,284
mgd
630
4,200
4,830
l,000mj/d
3,661
26,434
30,095
mgd
967
6,983
7,950
Percent of total
that is ground water 13 12
WASHINGTON
Ground water 1,325 350 3,173 838
Surface water 20,062 5,300 23,976 6,334
Total: 21,387 5,650 27,149 7,172
Percent of total
that is ground water 6 12
WYOMING
Ground water 492 130 875 231
Surface water 19,684 5,200 19,916 5,261
Total: 20,176 5,330 20,791 5,492
Percent of total
that is ground water 2 4
GRAND TOTAL
Ground water
Surface water
Total:
19,581
175,264
194,845
5,173
46,300
51,473
25,801
193,036
218,837
6,816
50, 995
57,811
Percent of grand total
that is ground water 10 12
11
-------
NORTH
^**«*irt-^^ I
. .
MONTANA |
I
^ X
_...^j WYOMING
4%
— ...-i2AHO_J V J
12%
GROUND WATER
SURFACE WATER
I COLORADO
*$%««*• 15%
Figure 1. Comparison of ground-water use to surface-water use in 1970.
-------
10.0
$.0
8.0
o 7.0
UJ
a.
2 6.0
UJ
UJ
o 5.0
CD
ID
O
0 4.0
1
3.0
2.0
If\
.(J
n
—
—
—
—
-
-
-
-
1
'^^j^M
I
IRRIGATION
INDUSTRIAL
RURAL
PUBLIC SUPPLY
(EXCLUDING SALINE WATER AND
WATER USED FOR THERMOELECTRIC
POWER GENERATION)
2.5
2.0 >
<
o
ac.
UJ
a.
v>
1.5 3
(5
1.0
O
0.5
COLORADO
IDAHO
MONTANA OREGON WASHINGTON WYOMING
Figure 2. Use of ground water in 1970. '
-------
from wells.
Irrigation water use is large and represents 89 percent of
all water withdrawn in the project area. Ten percent of the
water used for irrigation supplies is derived from wells.
The states with the largest ground-water withdrawal for ir-
rigation are Idaho (9.7 cu hm/d or 2.6 bgd) and Colorado
(7.8 cu hm/d or 2.1 bgd).
TRENDS IN. GROUND-WATER USE
Projections of water use in the United States indicate that
sharp increases may be expected in municipal, self-supplied
industrial and agricultural water use in the next 30 years.
By the year 2000, self-supplied industrial water demand will
triple, municipal water use will double, and the agricul-
tural demand will increase some 50 percent. 4) Projected
fresh water withdrawals for the steam-electric power indus-
try will increase by about 400 percent in the same period.
New mining development of oil shale and coal in Montana,
Wyoming and Colorado will require large quantities of water
for cooling and processing. In the Great Plains, surface-
water rights claim most runoff and no or very few additional
surface-water diversions are possible. For these reasons,
it is expected that ground water will play an increasingly
important role in water development.
A comparison of water-use data for the years 1965 and 1970
shows some interesting trends in ground-water use (see Table
2). 1/11) Total ground-water use for the study area in-
creased 9 percent in the five-year period, or roughly 2 per-
cent per year. On a state basis, however, except for Idaho,
the increase was considerably more and ranged from 15 per-
cent in Washington to 136 percent in Wyoming.
By category the following trends appear:
Public Supply - There is a general increase in ground-water
use in all states, most pronounced in Colorado (40 percent)
and Washington (16 percent).
Rural Supply - Generally a slight increase except in Oregon
where rural ground-water use jumped from 136,000 to 606,000
cu m/d (36 to 160 mgd). This appears to be indicative of a
rapid growth of self-supplied homes outside the urban areas.
Industrial Supply - Generally on an upward trend except in
Oregon where ground-water use decreased from 606,000 to
416,000 cu m/d (160 to 110 mgd). A large change took place
14
-------
Table 2. GROUND-WATER USE, 1965-70. ]'1])
(in mgd)
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
1965
I,000m3/d
6,185 1
11,408 3
307
2,680
2,767
371
mgd
,634
,014
81
708
731
98
1970
1,000 m3/d
7,809 2
9, 720 2
564
3,661
3,173
875
mgd
,063
,568
149
967
838
231
Percent of
increase (+)
or
decrease (-)
over 1965
+ 26
- 15
+ 84
+ 37
+ 15
+ 136
15
-------
in Idaho where ground-water use increased from 344,000 to
1,287,000 cu m/d (91 to 340 ragd). This is believed to be
due to increased industrial development in the food process-
ing sector.
Irrigation - This category showed the most change with con-
siderable increases (20 to 40 percent) in ground-water use
(except for Idaho). The increase in Colorado was 26 percent;
Oregon, 40 percent; and Washington, 21 percent. Irrigation
with ground water in Montana increased from zero in 1965 to
238,000 cu m/d (63 mgd) in 1970. In Wyoming, irrigation
with ground water multiplied several times from 102,000 to
492,000 cu m/d (27 to 130 mgd). Use of ground water in
Idaho, however, dropped 25 percent from 10.6 to 7.8 cu hm/d
(2.8 to 2.1 bgd). It is believed that this reduced with-
drawal represents, at least in part, a change-over from
ditch irrigation to overhead spray irrigation, which uses
less water.
16
-------
REFERENCES CITED
SECTION III
1. Murray, C. R., and E. B. Reeves, "Estimated Use of Wa-
ter in the United States in 1970," U. S. Geological
Survey, Circular 676, 1972.
2. National Water Commission, "Water Policies for the Fu-
ture," U. S. Government Printing Office, 1973.
3. McGuinness, C. L., "The Role of Ground Water in the Na-
tional Water Situation," U. S. Geological Survey, Water-
Supply Paper 1800, 1963.
4. Water Resources Council, "The Nation's Water Resources,"
Superintendent of Documents, U. S. Government Printing
Office, Washington, D. C., 1968.
5. Fuhriman, D. K., and J. R. Barton, "Ground-Water Pollu-
tion in Arizona, California, Nevada and Utah," Environ-
mental Protection Agency, Office of Research and Mon-
itoring, Water Pollution Control Research Series 16060
ERU 12/71, 1971.
6. Scalf, M. R., J. W. Keeley, and C. J. LaFevers, "Ground
Water Pollution in the South Central States," Environ-
mental Protection Agency, Office of Research and Moni-
toring, Environmental Protection Technology Series EPA-
R2-73-268, 1973.
7. Miller, D. W., F. A. DeLuca, and T. L. Tessier, "Ground-
Water Contamination in the Northeast States," Environ-
mental Protection Agency, Office of Research and Devel-
opment, Environmental Protection Technology Series,
EPA-660/2-74-056, 1974.
8. Durfor, C. N., and Edith Becker, "Public Water Supplies
of the 100 Largest Cities in the United States, 1962,"
U. S. Geological Survey, Water-Supply Paper 1812, 1965.
9. Office of Saline Water, "Feasibility of Desalting Mu-
nicipal Water Supplies in Montana," OSW Research and
Development Progress Report 783, 1972.
10. Gregg, D. O., and others, "Public Water Supplies of
Colorado, 1959-60," Colorado State University, Agricul-
tural Experiment Station, General Series 757, 1961.
17
-------
11. Murray, C. R., "Estimated Use of Water in the United
States, 1965," U. S. Geological Survey, Circular 556,
1968.
18
-------
SECTION IV
DESCRIPTION OF PROJECT AREA
The project area encompasses the six states of Colorado,
Wyoming, Montana, Idaho, Oregon, and Washington, an area of
roughly 1.5 million sq km or 600,000 sq mi, representing 20
percent of the total land surface of the conterminous United
States. The project area is characterized by a wide variety
of land-form features. Large physical divisions are the
Great Plains, the Rocky Mountains, Intermontane Plateaus,
the Pacific Mountain System, and numerous large basins and
lowland regions. Elevations of the-land surface range from
sea level along the Pacific coast to over 3,000 m or over
10,000 ft in the Rocky Mountain region.
PHYSIOGRAPHY
In 1951, H. E. Thomas divided the United States into 10 dis-
tinct ground-water regions. 1) Within the boundaries of the
project area, the following seven regions are present:
1. Western Mountain Ranges
2. Alluvial Basins
3. Columbia Plateau
4. Colorado Plateau and Wyoming Basin
5. High Plains
6. Unglaciated Central Region
7. Glaciated Central Region
These seven ground-water regions together with principal
aquifers and centers of major ground-water withdrawal are
shown in Figure 3. Almost half of the project area lies
within the Western Mountain Ranges. Also encompassing large
areas are the Columbia Plateau and the Unglaciated Central
Region. Of relatively small extent are the Alluvial Basins
and the High Plains Region.
The Western Mountain Ranges include the Coast and Cascade
Ranges in Oregon and Washington, the Olympic Mountains in
Washington, the Bitterroot Range, Clearwater and Salmon
River Mountains, in Idaho, and the Rocky Mountains in Montana,
Wyoming and Colorado. It is in this region, which includes
some of the most spectacular mountains of the nation, that
the principal source of water in the project area originates.
The bulk of the precipitation falls on these mountains and
gives rise to great rivers, among which are the Snake, Co-
lumbia, Missouri, Platte, Arkansas, Rio Grande, and Colorado.
The mountains generally consist of hard or crystalline rock
19
-------
GROUND-WATER
REGIONS
Western Mountain
Ranges
Alluvial Basins
Columbia Plateau
Colorado Plateaus (a)
Wyoming Basin (b)
High Plains
Unglaciated
Central Region
Glaciated
Central Region
to
o
V V
v v
VVVVVV
V V V V V V ¥
v*v v ipt v
V V V*V
UNCONSOLIDATED AQUIFERS
CONSOLIDATED ROCK AQUIFERS
Sandstone
Sandstone and carbonate rocks
Volcanic rocks, chiefly basalt
•_•. V Sand and gravel deposits En
intermontane valleys, alluvial
valley, sand dunes and glacial
Ruled pattern indicates that consolidated rock deposits
aquifer underlies sand and gravel aquifer
Represents pumpage of 100 million cu m/year
or 72 million gal Ions/day ( 1965)
200
J
100
ZOO Ml.
Figure 3. Ground-water regions and major aquifers. '' '
-------
and form poor aquifers. However, alluvial deposits and gla-
cial outwash in valley areas can constitute prolific aqui-
fers. An example of the latter are the glacial outwash de-
posits in the Spokane Valley-Rathdrum Prairie area in Wash-
ington and Idaho.
The Alluvial Basins are structural depressions that were
filled with unconsolidated material in Pleistocene and Recent
times. They form the natural collection areas for stream-
flow from the surrounding uplands. The region includes the
Willamette River basin in Oregon, the Puget Sound Lowland in
Washington, and the San Luis Valley in Colorado. The Puget-
Willamette Trough lies between the Coast Range and the Cas-
cade Range. This lowland is intensively developed and urban-
ized in the Portland and Seattle-Tacoma region. The San
Luis Valley is an important irrigated agricultural area and
the site of the largest ground-water withdrawal in Colorado.
The Columbia Plateau ground-water region is bounded on the
west and north by the Cascade Range and to the east by the
Rocky Mountains. It covers eastern Washington, eastern Ore-
gon, and southern Idaho. The Plateau consists of lava rocks,
hundreds of meters thick in places, with permeable zones
that constitute enormous and highly productive aquifers.
The lava plateau receives excellent recharge from infil-
trating streams. The plateau is deeply dissected by streams
and depth to ground water is great in some areas. The aqui-
fer is widely tapped for irrigation in the Snake River Plain
of Idaho.
The Colorado Plateau and the Wyoming Basin are regions under-
lain by sedimentary rocks, chiefly interbedded sandstone and
shale. The plateaus are deeply dissected by the Colorado
River and the Missouri River and their tributaries. Com-
pared with the Columbia Plateau, the rocks have low permea-
bility and receive fairly little precipitation. Both pla-
teaus are water-poor areas with low runoff and relatively
poor aquifers. Alluvium is present in the principal stream
valleys, and important alluvial basins are found along the
Yampa and Green Rivers in northwestern Colorado and the
Sweetwater River in Wyoming. Extensive oil-shale deposits
also are present within the region.
The High Plains ground-water region of eastern Colorado and
eastern Wyoming constitutes the northwestern edge of an im-
mense alluvial deposit laid down on sedimentary rocks in
Tertiary time. This alluvium, which in places is over 160 m
(500 ft) thick, extends into Kansas and Nebraska and south-
ward into Oklahoma and Texas. It is known as the Ogallala
Formation. Precipitation is low and natural replenishment
21
-------
to the Ogallala aquifer is very small. In recent years, the
northern part of the Colorado High Plains has undergone a
change from dry land to irrigated agriculture using water
from the Ogallala Formation.
The Unglaciated Central Region in Montana, Wyoming and Colo-
rado is part of the vast interior region of the United
States. It is characterized by plains and plateaus under-
lain by horizontal or gently eastward-dipping sedimentary
rocks. Aquifers in most of the region are sandstones, gen-
erally of relatively low yield. Some productive limestones
(e.g. the Madison) are present in Montana and Wyoming. Sa-
line ground water is generally present at shallow depths
over most of the region and saline springs are common in
Montana. Included within the region is the Denver Basin in
Colorado, an area of intensive ground-water development.
The Glaciated Central Region covers a strip some 160 km (100
mi) wide along the Canadian border in Montana. The region
is quite similar to the Unglaciated Central Region in physi-
ography and rock types. However, a mantle of glacial drift
overlies the bedrock. This drift consists mostly of fine-
grained rock debris (till) and contains almost no beds of
permeable material. Principal aquifers are found along wa-
ter courses where the rivers have washed away fine-grained
material from the glacial deposits, leaving behind permeable
sands and gravels. Recharge to the underlying bedrock aqui-
fers is small, due to low precipitation and the drift cover.
General geologic conditions in the project area are shown on
Figure 4. The map shows the type of bedrock and distin-
guishes between crystalline rock (igneous and metamorphic
rocks), volcanic rocks, and sedimentary rocks. Major areas
of unconsolidated material in river valleys, plains and in-
termontane valleys are also shown. Volcanic and crystalline
rocks cover well over 50 percent of the project area.
Investigations of ground-water conditions have been carried
out through cooperative programs between state agencies and
the U. S. Geological Survey and by state universities. Gen-
eral ground-water information is available for about 50 per-
cent of the project area, but almost no information is
available for the little-populated mountain zones. Detailed
ground-water studies have been carried out in only a few
urban areas.
POPULATION
Of the nation's 203.2 million people, some 9.5 million or
4.7 percent resided in the project area according to the
22
-------
-// V V
vvvvvvvv
vy^/v v v v v
™:-'\v v v v v v
y v v v X5jT •
V V
VVV
v y/s? v
/V V V/K-:
vvv vf.:
V V^)V-C V V V V
vvvvvvvvv
VVVVVVV
vJ.:-:-sy y v Vtiv^a^ot v v v v v v v
"^X'i\f/ v v vvv vvv v v v/S
(s/vvvvvvvvvv
vvvvv.vvvvvvvvvvv
W ^ ^ xy^B/ w w w
Unconsolidated Rocks
Sedimentary Rocks
[/ v v v \j Volcanic Rocks
j^g) Crystalline Rocks
Figure 4. Geology of Hie norfhwest-ern states.
-------
1970 Census. 4) characteristics of the population in each
state are shown on Table 3. Colorado, Oregon and Washington
have the highest population and show a relatively large in-
crease in population in the 1960-70 period (18 to 25 per-
cent) . In these states, most of the population is concen-
trated in urban- centers. By contrast, Wyoming, Montana and
Idaho have a small population which is mostly rural and has
shown little increase over the years. The largest cities in
the project area are Denver (pop. 512,691), Seattle (pop.
524,263), and Portland (pop. 375,161). Important regional
concentrations of population are the Seattle-Tacoma urban
area (pop. 2,000,000), and the Greater Denver metropolitan
area (pop. 1,200,000). Population growth in the metropoli-
tan areas is expected to continue in the next 20 years. The
population of the Denver area, which contains more than 75
percent of the total population of Colorado, is projected to
be'over 2,000,000 by 1990. 5)
CLIMATE
Climatic conditions vary widely in the project area because
of the varied topography and movement of air masses across
the continent. The Pacific zone has a coastal-marine cli-
mate, with high precipitation (Figure 5), high runoff (Fig-
ure 6) and low evaporation rates. Eastward the climate be-
comes the high-desert type with low precipitation, low run-
off and high evaporation rates. Locally, mountain ranges
cause wide variations in climatic conditions.
About 60 percent of the project area is water-deficient (Fig-
ure 6). The Pacific coastal zone, especially the western
slopes of the Coast Range and Cascade Range, is one of the
areas of highest precipitation in the United States (2,000
to 3,500 mm or 80 to 140 in per year). A sharp drop in
precipitation takes place east of the Cascade Range. Pre-
cipitation is generally less than 500 mm (20 in) per year
over Idaho, Montana, Wyoming and Colorado. Snowfall is
heavy in the Rocky Mountains, the Cascade Range and in north-
eastern Oregon, and locally reaches 2,500 to 5,000 mm (100
to 200 in) per year. Snow melt in spring provides heavy run-
off that, when stored in reservoirs, becomes available for
water supply.
GEOLOGY AND GROUND-WATER RESOURCES
Following is a discussion of the general geology in relation
to the ground-water resources on a state-by-state basis.
For each state, surface-water resources are briefly dis-
cussed followed by a review of ground-water use. Hydrogeo-
logic conditions in each of the major river basins and water-
24
-------
Table 3. POPULATION CHARACTERISTICS.
4)
tsj
01
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
1970
Population
2,207,259
713,008
694,409
2,091,385
3,409,169
332,416
Percent increase
1960 to 1970
25.8
6.9
2.9
18.2
19.5
0.7
Places over
25,000
population
10
4
3
5
11
2
Places over
100,000
population
2
None
None
1
3
1
Population distribution
(percent)
Urban Rural
75
48
51
65
69
58
25
52
49
35
31
42
TOTAL:
9,447,646
12.3
35
-------
to
cr>
NORTH
.5>n~»MEAN ANNUAL PRECIPITATION
IN INCHES
Figure 5. Mean annual precipitation.
-------
NORTH
KJ
-—20—Mean annual runoff in inches
Area of water surplus
JArea of water deficiency
100
i
Figure 6. Mean annual runoff
-------
bearing characteristics of principal aquifers are described.
Colorado
Colorado is an area of mountains and high plateaus and
plains lying across the highest part of the Continental Di-
vide. Precipitation is 500 to 750 ran (20 to 30 in) in the
mountainous area but drops to 300 to 400 mm (12 to 16 in) in
the eastern and western portions of the state and to 150 mm
(6 in) in the San Luis Valley. The Rocky Mountain area
forms the headwaters for such major western rivers as the
Platte, Arkansas, Rio Grande, and Colorado. Available flow
in the major rivers is some 53 cu hm/d, equivalent to 14 bgd
or 16 million acre-ft; however, under existing compacts and
decrees, about half of this water must be delivered to down-
stream states. Water of the South Platte, Arkansas, and Rio
Grande Rivers, about one-quarter of the total supply, is al-
ready fully appropriated, while that of the Colorado River,
about two-thirds of the total for the state, is expected to
be fully utilized within 50 years. Only about one-third of
the river flow of 37 cu hm/d (11 million acre-ft per year)
can be used within Colorado.
Concentration of the population in the water-short Lower
Platte River basin has created problems of water distribu-
tion and has necessitated diversion of Colorado River water
eastward to the Denver metropolitan area. Continued growth
of population and industrial development in the South Platte
and Arkansas basins will be limited, unless additional water
can be made available through importation, salvage and re-
use. 7)
The state's ground-water resources are largely east of the
Continental Divide. Major ground-water areas are shown on
Figure 7; principal aquifers and well yields are depicted
on Figure 8. The principal aquifers are the alluvial sand
and gravel deposits in the Platte and Arkansas River valleys
and in the San Luis Valley of the Rio Grande, and the Ogal-
lala Formation of the High Plains. Sandstones yielding mod-
erate supplies of ground water are important aquifers in the
Denver Basin and south of the Arkansas River between Pueblo
and the Kansas state line in the so-called Arkansas Valley
Artesian Area. West of the Divide the principal aquifers
are the alluvial deposits along the Yampa and Green Rivers,
and the sandstones of the Colorado Plateau and the Wyoming
Basin.
Ground-water use in the state is growing rapidly and the
total withdrawal amounts to over 7.5 cu hm/d (2.0 bgd).
Most of this water (95 percent) is used for irrigation in
28
-------
NJ
NORTH
SOUTH PLATTE
RIVER BASIN
FORT
COLLINS •
NORTHERN
HIGH
PLAINS
DENVER*DENVER X
GLENWOOD
SPRINGS*
GRAND
JUNCTION
COLORADO
• LEADVILLE
COLORADO
A SPRINGS
ROCKY
MOUNTAINS
ARKANSAS
RIVER BASIN
,' \ ARKANSAS ,
VALLEY '
I ARTESIAN
0
V
0
50 100 KM.
I I
I I
25 50 Ml.
Figure 7. Colorado - Major ground-water areas.
-------
U)
o
CONSOLIDATED ROCKS
Granite and undifferentiated
metamorphic and volcanic rocks
-§?] 0-6 l/s (0-100 gpm); maximum
of 6 l/s(100gpm)
Sandstone :
[TTTT1) 0-3 l/s (0-50 gpm); maximum of
13 l/s (200 gpm)
—rj 0-6 l/s (0-100 gpm); maximum of
18 l/s (300 gpm)
• >18 l/s (> 300 gpm)
UNCONSOLIDATED ROCKS
0.3-30 l/s (5-500 gpm)
y£| > 30 l/s ( 500 gpm)
50
100 Km
_l
Mi
UNDIFFERENTIATED ROCKS
Unconsolidated rocks:
0-3 l/s (0-50 gpm); along
streams, 3-60 l/s (50-
1,000 gpm)
Consolidated rocks: meager
amounts of poor quality watt
maximum of 3 l/s (50 gpm)
Figure 8. Colorado - Major aquifers and well yields
8)
-------
the South Platte and Arkansas River basins and in the San
Luis Valley. In recent years a rapid increase in irrigation
has taken place in the High Plains of eastern Colorado using
water from the Ogallala aquifer.
Surface water and ground water in the alluvial aquifers are
closely interrelated. Alluvial aquifers are recharged by
river water, and in turn, ground-water recharge, for example
from irrigation return flows, contributes heavily to the
flow of some rivers.
Ground-water studies have been made by the U. S. Geological
Survey, the Colorado Water Conservation Board (in coopera-
tion with the U. S. Geological Survey) and the Colorado
State Department of Public Health. In recent years, some
investigations on ground water and ground-water quality have
been carried out by Colorado State University-
South Platte River Basin -
The South Platte River basin is the most intensively devel-
oped irrigated area in Colorado. The water-bearing charac-
teristics of the valley-fill aquifers are excellent for de-
velopment of large, low-cost water supplies from shallow
wells for irrigation, municipal and industrial use. Wells
yield up to 190 1/s or 3,000 gpm, and yields of 30 1/s (500
gpm) are common.
The valley-fill deposits reach their maximum thickness in
the main South Platte River valley and in the lower reaches
of most of its tributaries. The saturated thickness of the
aquifer ranges from 12 to 40 m (40 to 120 ft) in the main
valley between the southern Weld County line and the town of
Kuner, is over 25 m (80 ft) in an area downstream of the
town of Orchard to the state line, and is 48 to 72 m (160 to
240 ft) in the lower basin. Depth to the water table in the
main valley is generally less than 3 m (10 ft) in the low-
lands and increases to about 15 m (50 ft) in the upland
areas. In the tributary river valleys, such as the lower
Cache la Poudre River and Boxelder Creek, the valley-fill
material generally ranges from 12 to 30 m (40 to 100 ft) in
thickness. Over 30 m (100 ft) are reported in the valleys
of Lost Creek, Bijou, Kiowa, Badger, and Beaver Creeks.
Dune sand deposits, which reach a thickness of 30 m (100 ft)
in places, cover an area of over 2,600 sq km (1,000 sq mi)
in Weld, Morgan, Logan, and Washington Counties. These de-
posits yield small quantities of water to wells but are im-
portant for infiltration of precipitation and runoff, and
thus, for recharge of underlying aquifers. 9)
31
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Bedrock aquifers are the crystalline Precambrian age rocks
exposed in the Front Range that yield small supplies (0.3 to
0.6 1/s equivalent to 5 to 10 gpm) to individual wells and
sedimentary rocks of Cretaceous age capable of yielding mod-
erate supplies to wells (0.6 to 5 1/s or 10 to 75 gpm). The
sedimentary rock aquifers are discussed separately in the
section describing the Denver Basin.
There are over 10,000 water wells in the South Platte River
basin, most of which tap the alluvial aquifer (Table 4).
Over 6,000 of these are large-capacity irrigation wells.
The volume of ground water moving through the alluvial aqui-
fer is large. The U. S. Geological Survey has estimated the
underflow in the alluvium of the main valley at 390 1/s
(10,000 acre-ft per year) north of Denver, 510 1/s (13,000
acre-ft per year) at Greeley, 470 1/s (12,000 acre-ft per
year) at Kersey and 310 1/s (8,000 acre-ft per year) at the
state line. Ground-water withdrawals have increased consid-
erably in the last few years. An estimated 1.5 billion cu m
(1.2 billion acre-ft) was pumped for irrigation in 1967 com-
pared with 900 million cu m (730,000 acre-ft) in 1959. Mu-
nicipal and industrial pumpage in recent years is estimated
at roughly 123 million cu m (100,000 acre-ft),.and the total
withdrawal of ground water is some 1.6 billion cu m (1.3
million acre-ft).
Over the years, seepage from surface reservoirs, canals and
surplus irrigation water has caused the water table to rise
above the river bed. The result was that the South Platte
River became a gaining stream carrying water on a year-round
basis. Downstream, irrigators filed for rights to use this
water and have become entirely dependent upon this "return
flow". 11) Recent studies of gaging records show that the
river gains some 70 1/s per km (2,900 acre-ft per mi) per
year between Denver and Julesburg. 9) The highest gains of
89 to 110 1/s per km (3,700 to 4,500 acre-ft per mi) per
year take place in the Fort Lupton-Fort Morgan stretch and
in densely irrigated areas.
Infiltration from seepage losses of irrigation conveyance
systems and percolation on irrigated farms is estimated at
50 percent of the South Platte River water diverted. Thus,
annually some 740 million cu m (600,000 acre-ft) enters the
unconfined aquifers in the agricultural area of the main
valley and its southern tributary valleys. In comparison,
infiltration into the valley-fill deposits from precipita-
tion is small and estimated at about one inch per year.
Monitoring of ground-water levels in the main valleys has
32
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Table 4. COLORADO. USE OF WATER WELLS IN SOUTH PLATTE RIVER
BASIN.9'10)
South Platte
Denver to Brighton to River Basin
Type Brighton State Line Total
Irrigation wells
Municipal water systems
Domestic, motels, restau-
rant, other
Industrial and commercial
Stock
397
38
546
85
10
5,063*
96
3,497
211
780
6,240
134
4,046
199
10
TOTALS:
1,076
9,647
10,629
Valley-fill aquifer only.
33
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shown no long-term decline indicating that the recharge bal-
ances withdrawals. 10) However, in some heavily pumped
tributary valleys, such as Prospect Valley and the areas of
Kiowa, Bijou, and Beaver Creek, long-term water levels are
declining at the rate of about one ft per year. 7)
Arkansas River Basin -
The Arkansas River valley is the third most productive irri-
gated area in Colorado with hydrologic conditions quite sim-
ilar to those of the South Platte River basin. The main
river valley and tributary valleys are intensively irrigated.
Water is obtained from the Arkansas River and from ground
water present in the alluvium, which is an excellent aquifer
with high transmissivities. The aquifer occupies a trough
eroded into shale, limestone and sandstone bedrock of Creta-
ceous age. This bedrock is relatively impermeable and acts
as a barrier to ground-water movement. In Bend County (Las
Animas region), the saturated thickness of the valley fill
varies from 3 to 20 m (10 to 60 ft), and the transmissivity
in the main valley varies from 1,200 to 3,700 sq m/d
(100,000 to 300,000 gpd/ft).
The saturated valley-fill deposits range in thickness from 0
to 75 m (250 ft) and contain an estimated 2.5 billion cu m
(2 million acre-ft) of water in storage. 12) The aquifer is
in hydraulic connection with the Arkansas River. Irrigation
water is diverted from the Arkansas River and also pumped
from wells. Surface-water diversions averaged 940 million
cu m (760,000 acre-ft) per year and ground-water withdrawals
173 million cu m (140,000 acre-ft) per year during the
period 1958-1968.
The major part of the irrigation return flow discharges to
the Arkansas River as revealed by river gaging records. For
example, along an 8 to 13 km (5 to 8 mi) stretch of the
river downstream of Las Animas, the river gained 1,330 1/s
or 47 cfs on October 31, 1967. 12) Since the start of sur-
face-water irrigation in 1859, some 24 canals have been con-
structed to divert water from the Arkansas River for appli-
cation ori the land between Pueblo and the Kansas state line.
Streamflow is derived from precipitation - chiefly snowmelt
in the Rocky Mountains. In late summer, the surface-water
supply is commonly inadequate to meet irrigators1 needs.
Wells drilled mostly between 1950 and 1965 are needed to
provide irrigation water when surface supplies are deficient.
In 1969 there were some 1,350 irrigation wells tapping the
valley-fill aquifer in the Arkansas River valley. 12)
Ground-water withdrawal for irrigation averaging 102 million
34
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cu m (83,000 acre-ft) per year from 1950 to 1959, increased
to 173 million cu m (140,000 acre-ft) per year in the 1960
to 1969 period. The yield of irrigation wells varies from 6
to 160 1/s (100 to 2,500 gpm) .
Aside from the valley-fill aquifer, small to moderate sup-
plies of ground water can be obtained from Cretaceous sand-
stones (Cheyenne Sandstone of the Purgatoire Formation and
Dakota Sandstone). These formations are present below the
entire Arkansas River basin but are only within reasonable
drilling depth in the area south of the Arkansas River from
Carson City to the Kansas state line. This region is called
the Arkansas Valley Artesian Area. The sandstones yield
small to moderate supplies of 0.6 to one 1/s (10 to 15 gpm)
to wells, with exceptionally higher yields (greater than 20
1/s or 300 gpm) in areas where the formation is coarse-
grained (Baca and Prowers Counties). The sandstones are
primarily tapped by domestic and municipal wells, but in
high-yield areas the aquifers are pumped for irrigation.
The present withdrawal is not known, but in 1959 municipal
wells pumped some 3 million cu m (2,400 acre-ft). 7)
Denver Basin -
The Denver Basin surrounds the city of Denver, extending on
the west to the mountains and some 130 to 200 km (50 to 75
mi) north, east and south of the city. Ground water is ob-
tained from alluvial deposits in the South Platte River val-
ley and its tributaries and from a sequence of sedimentary
rock aquifers, some of which are unconsolidated in nature.
The alluvial deposits reach a maximum thickness of 20 m (60
ft) and yield large quantities of water where sufficiently
saturated. Municipal water wells producing from the allu-
vium in the Cherry Creek valley, for example, yield from 55
to 115 1/s (900 to 1,800 gpm). 14) The principal bedrock
aquifers are the Dawson and Laramie Formations and the Fox
Hills Sandstone. Older Mesozoic and Paleozoic formations
are capable of yielding small to moderate quantities of wa-
ter to wells, but because of their great depth, these aqui-
fers are not developed.
The upper part of the Dawson Formation (thickness 100 to 335
m or 300 to 1,100 ft) is composed of shale, clay, siltstone,
sandstone and beds of arkosic conglomerate, sand and gravel,
and some beds of lava and tuff. The conglomerate zone ("up-
per conglomerate") and lenticular gravel beds that lie from
60 to 120 m (200 to 400 ft) above the conglomerate zone
yield moderate amounts of water. The lower part of the
Dawson Formation (thickness 120 to 460 m or 400 to 1,400 ft)
35
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consists of arkosic sand, gravel, and conglomerate interbed-
ded with shale and clay. The thickest and most extensive
zones of coarse sediments in the upper 230 m (700 ft) are
known as the "middle" and the "lower conglomerate". Each of
these zones ranges in thickness from 16 tb 60 m (50 to 200
ft) and yields moderate quantities of water.
Below the Dawson Formation is the Laramie Formation which is
composed of sandstone, limestone, lignite and coal beds.
Two sandstone beds in the formation, known as the "A" sand-
stone and "B" sandstone, each 10 to 30 m (30 to 100 ft)
thick, yield small to moderate supplies of water to wells.
The Milliken Sandstone member of the Fox Hills Sandstone
found below the Laramie Formation constitutes the lowest
principal aquifer in the basin. This sandstone yields small
to moderate quantities of water.
Long-term pumpage from the Dawson and Fox Hills aquifers in
the Denver area has created local cones of depression of 100
to 200 m (300 to 600 ft), and pumping lifts are now consid-
erable. 7) Artificial recharge of the aquifers through
wells appears to be feasible.
High Plains -
The High Plains ground-water reservoir in eastern Colorado
lies within the Kansas River basin and extends into the
Arkansas River basin. The principal aquifer is the Ogallala
Formation which extends beyond the state line and underlies
large areas in Texas, Oklahoma, Kansas and Nebraska. The
formation consists of clay, silt, sand, and gravel and var-
ies considerably in thickness and permeability from place to
place. The sediments were deposited on an irregular, slop-
ing bedrock surface and the formation thickens eastward to
about 120 m (400 ft) at the Kansas state line. Dune sand
overlies about 4,000 sq km (1,600 sq mi) of the Ogallala in
the northern High Plains. Upper Cretaceous shales and silt-
stones underlie the Ogallala.below the northern High Plains
and form an almost impermeable barrier. Further south the
aquifer is underlain by shales and sandstones.
The Ogallala is widely tapped by municipal, domestic and ir-
rigation wells. In recent years, a significant rise in the
rate of new irrigation wells drilled has caused concern for
proper management of the resource in view of a low recharge
rate to the aquifer. 7)
In the southern Plains region, the Dakota and Cheyenne Sand-
stones are present below the Ogallala. These sandstone
aquifers are also quite irregular in thickness, depth and
36
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extent, and are typically separated from the Ogallala by
shale beds of the Pierre Formation. Where confined, the
Dakota and Cheyenne are artesian, and can supply moderate
quantities of water; however, the aquifers are little de-
veloped. Other aquifers are permeable sandstones within the
White River Group of Oligocene age and alluvial deposits in
river channels.
Water levels in the Ogallala aquifer are low as a result of
the incised river drainage, and only about the lower one-
third of the formation is saturated. The thickness of sat-
urated material in the formation ranges from a few feet
along the western edge of the High Plains to about 115 m
(350 ft) in the eastern part. Low water levels cause pump-
ing lifts to be on the order of over 50 m (several hundred
ft). The necessity for deep wells and the high electric
power costs cause this irrigation water to be the most ex-
pensive in the state.
The amount of water stored within the Ogallala is tremendous.
The aquifer covers an area of approximately 30,000 sq km
(12,000 sq mi) in Colorado, and assuming a saturated thick-
ness of 30 to 50 m (100 to 150 ft), the total amount of wa-
ter in storage is estimated at 185 billion cu m (150 million
acre-ft). 7) Annual recharge from precipitation has been
calculated by the U. S. Geological Survey to be 20 to 23 mm
(0.8 to 0.9 in), which is equivalent to some 530 million
cu m (430,000 acre-ft). 15) The natural hydraulic gradient
of the water table in the Ogallala is eastward, and ground
water flows from the High Plains into Nebraska and Kansas.
This underflow is estimated at 480 million cu m (390,000
acre-ft) per year. 16)
The number of irrigation wells tapping the Ogallala aquifer
is estimated at over 3,000. Of these, 2,550 were located on
the northern High Plains and irrigated over 81,000 ha or
200,000 acres in 1971. 17) Some 700 additional wells (as of
1966) were operating in the southern High Plains. Yields of
wells range up to 125 1/s (2,000 gpm) . However, in general,
irrigation wells yielding 30 1/s (500 gpm) and over can only
be developed where the saturated thickness is more than 16 m
(50 ft). Total pumpage from the Ogallala aquifer is esti-
mated at over 617 million cu m (500,000 acre-ft). In 1971,
pumpage in the northern High Plains was 529 million cu m
(429,000 acre-ft), an increase of 28 million cu m (23,000
acre-ft) over 1964. More than 148 million cu m (120,000
acre-ft) of ground water were utilized in the southern High
Plains in 1965.
The rush from dry land to irrigated agriculture during the
37
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1960's caused concern for over-pumpage and falling water
levels. The number of irrigation wells was increasing, rap-
idly, (the peak was reached in 1968 when some 390 irrigation
wells were drilled), and ground-water pumpage was increasing
sharply. Water- levels declined as much as 5m (16 ft) in
some areas. To prevent excessively low water levels, simi-
lar to conditions now prevailing in the High Plains of New
Mexico, Texas, and Oklahoma, economic studies were made and
measures were taken to control ground-water development.
The Colorado Water Conservation Board now denies well-permit
applications in all areas where existing wells could be ex-
pected to deplete the saturated thickness by more than 40
percent in 25 years. 18) The "40 percent rule" has been
adopted as the maximum depletion rate by the state and the
High Plains Water Management Districts. As a result, since
1969, well drilling has dropped off sharply, and well per-
mits can now only be obtained in a few isolated areas on the
Colorado High Plains.
A network of 1,044 water-level observation wells was estab-
lished in 1970 to monitor changes of storage in the Ogallala
aquifer and to provide data for evaluation of water manage-
ment plans using digital models. The network consists of
801 irrigation wells, 218 stock and domestic wells, and 25
U. S. Geological Survey observation wells. Seasonal water-
level fluctuations vary as much as 5.5 m (18 ft). There is
a net decline in water levels of about one m (3 ft) per year
in areas of heavy pumpage. 17)
San Luis Valley -
The San Luis Valley is a large, north-trending structural
basin downfaulted on the eastern border and covering some
7,800 sq km (3,000 sq mi). The valley is underlain by as
much as 10,000 m (30,000 ft) of alluvium, volcanic deposits
and lava flows, the latter frequently impeding the vertical
movement of ground water. Ground water is obtained from un-
confined and confined aquifers. Extensive clay beds ranging
in thickness from 3 to 25 m (10 to 80 ft) divide the valley
fill into an upper group of water-table aquifers and a lower
group of artesian aquifers. The unconfined aquifer varies
in thickness from 0 to 65 m (200 ft), and the artesian aqui-
fers range in thickness from 17 m (50 ft) to hundreds of m
or several thousand ft. The confining beds are, however,
discontinuous and lenticular, and the water-table and arte-
sian aquifers are connected hydraulically in varying degrees.
The aquifers are tapped by an estimated 10,000 water wells,
and the valley constitutes Colorado's largest single ground-
water development.
38
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The basin is drained by the Rio Grande, but the northern
portion, called the "closed basin," is drained internally.
The lowest part of this closed basin, covering some 650 sq
km (250 sq mi), is known locally as the "sump". Inflowing
surface and ground water applied for irrigation evaporates
in this area.
Recent studies show that the San Luis Valley has an abundant
supply of both surface and ground water. 19) The surface-
water supply averages 1.9 billion cu m (1.5 million acre-ft)
per year, and ground-water withdrawals average 925 million
cu m (750,000 acre-ft) per year (period 1962-1967). In ad-
dition, the valley-fill sediments contain more than 2.5
trillion cu m (2 billion acre-ft) of water in storage, a
quantity considered adequate to cover consumptive use for
1,000 years.
The principal source of water for irrigation is ground water,
but until 1950 surface water was used exclusively. Lands in
the eastern and central parts of the closed basin were irri-
gated by means of a network of canals, resulting in exten-
sive waterlogging. Drainage systems to reclaim these lands
were then constructed, but these proved only partially suc-
cessful as they created similar problems further downstream.
In 1967, there were about 2,800 large capacity wells (yield-
ing 20 1/s or 300 gpm and more), 2,160 of which tapped the
water-table aquifer. The greatest concentration of these
large-capacity wells is in the Rio Grande alluvial fan area
north of Alamosa.
The total amount of ground water pumped per year is some 925
million cu m (750,000 acre-ft). Of this amount, 555 million
cu m (450,000 acre-ft) is withdrawn by shallow, large-
capacity irrigation wells; small-capacity wells in the con-
fined aquifer contribute 370 million cu m (300,000 acre-ft).
Approximately 7,000 small-capacity wells flow, uncontrolled,
throughout the year, and it is estimated that some 185 mil-
lion cu m (150,000 acre-ft) of water is wasted and need-
lessly contributes to waterlogging. Municipal and indus-
trial water-supply wells pump a small quantity of water,
with municipal water use at 3.6 million cu m (2,900 acre-ft)
and industrial use at 420,000 cu m (340 acre-ft) in 1959. 7)
The Rio Grande alluvial fan, which is largely saturated,
acts to regulate the water supply in the closed basin.
Ground water withdrawn during periods of low surface-water
flow is replenished during high-flow periods. Over the
years, due to irrigation, the water level in the alluvial
fan has risen above the level of the Rio Grande, causing
39
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the river to gain flow between Del Norte and Monte Vista.
This rise in the water table has also created a ground-
water divide north of and parallel to the Rio Grande. To
the north of the divide, ground water moves toward the
closed basin, and toward the south, it moves toward the Rio
Grande.
Major water problems in the San Luis Valley are: 1) water-
logging, 2) waste of water by non-beneficial evapotranspira-
tion, 3) deterioration of ground-water quality, and 4) fail-
ure of Colorado to deliver water to New Mexico and Texas in
accordance with the Rio Grande Compact. Under the Compact
of 1940 with New Mexico and Texas, certain quantities of wa-
ter have to be delivered downstream, but since 1952, water
deliveries have been deficient. The U. S. Bureau of Recla-
mation has proposed a plan to salvage water now lost by
evapotranspiration in the closed basin and transport it to
the Rio Grande. An electric analog model evaluation of such
a water salvage plan has been prepared. 20) The U. S. Geo-
logical Survey is collecting basic data for preparing alter-
natives in water management, and a network of 334 observa-
tion wells has been established. The network consists of
184 irrigation wells; 31 stock, domestic and unused wells;
and 119 U. S. Geological Survey observation wells.
Western Colorado -
This region takes in the western half of the state and in-
cludes the central highlands underlain by crystalline rocks
and the sedimentary formations of the Colorado River basin.
It is a sparsely populated region with a small water demand
mainly for cattle watering, mining, lumbering, and tourism.
Development of land and water resources in the region has
been slower than in eastern Colorado due to limited availa-
bility of land suitable for irrigation, rugged topography,
and climate. The occurrence and quality of ground water
varies widely from aquifer to aquifer and with depth. In-
tensive ground-water investigations in the northwestern por-
tion and in the Piceance Creek basin have been started in
recent years. 21,22,23)
The mountainous area is composed of hard, dense igneous and
metamorphic rocks that yield only small quantities of water
to wells. Water is generally contained in the upper weath-
ered and fractured zone. Several structural basins, so-
called "parks" within the crystalline rocks, are underlain
by alluvial and terrace deposits, and in some cases, by
Tertiary sediments. Ground water is little utilized in
these parks because streams are used for most water supplies,
40
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Extensive urban development of the foothill and mountain re-
gions near Denver has taken place in recent years. In these
areas, practically all homes depend on individual wells for
water supply. For this reason the crystalline rock is an im-
portant aquifer in spite of its low yield to wells.
Probably the most prolific aquifers are the valley-fill de-
posits along the rivers and streams, including the Yampa,
Little Snake, Green, Colorado and Uncompahgre Rivers. Al-
though the valleys are relatively narrow (less than 1.6 km
or one mi), the sand and gravel beds yield moderate to large
quantities of water to wells. Yields of 0.3 to 6 1/s (5 to
100 gpm) are common, and in deeper valleys, numerous wells
yield as much as 60 1/s (1,000 gpm). 7) Most valley-fill
aquifers are in hydraulic connection with adjacent streams,
and large ground-water withdrawals reduce streamflow during
dry periods.
The occurrence of ground water in the Green River Formation
has been studied in the Piceance Creek basin, but elsewhere
almost no information is available. Water is present in the
fractures of the sandstone and in solution openings where
mineral deposits have been leached by moving ground water.
In the Piceance Creek basin, water stored in the leached
zone amounts to 3 billion cu m (2.5 million acre-ft).
The Mesaverde Group of Cretaceous age is the thickest of the
major aquifers. The rocks are composed of sandstone, shale,
and thin to massive coal beds. Well yields range up to 40
1/s (600 gpm).
The Dakota Sandstone, widely present in the area, is com-
posed of sandstones separated by shale beds. Well yields
are generally less than 3 1/s (50 gpm), but wells tapping
both the Dakota and the underlying Entrada Sandstone com-
monly yield more than 6 1/s (100 gpm).
The Leadville Limestone of Mississippian age lies at great
depth below much of the region and locally supplies large
quantities of ground water under high artesian pressure.
The use of ground water in western Colorado is small com-
pared to the use of surface water. In the northern and cen-
tral parts of western Colorado, ground-water withdrawal from
some 4,000 wells was about 30 million cu m (24,700 acre-ft)
in 1970. In the same year, 7.4 billion cu m (6 million
acre-ft) of surface water was diverted, mostly for irriga-
tion. 21)
41
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Idaho
Idaho is a state of high mountains and plateaus situated
west of the Continental Divide. Precipitation varies from
1,200 mm (48 in) per year in the Rocky Mountains along the
Idaho-Montana border, to 400 mm (16 in) in the north and 200
mm (8 in) in the Snake River Plain. Major rivers are the
Kootenai, Pend Oreille and Spokane Rivers in the north and
the Snake River in the south. The average annual runoff is
about 230 mm (9 in), which is equal to 142 million cu m per
day (37 bgd), or 42 million acre-ft per year. 7) Three
quarters of the runoff originating in Idaho is discharged by
the Snake River which traverses southern Idaho and supplies
large quantities of water for irrigation. Some 1.4 million
ha (3.4 million acres) of land on the Snake River Plain are
irrigated, and between 18 and 25 million cu m (15 and 20
million acre-ft) of river water is diverted per agricultural
season. 24) Basaltic lava flows in the Snake River Plain
and glacial outwash deposits in the Rathdrum Prairie-Spokane
Valley area are the state's most important aquifers.
Ground water supplies 14 percent of the water demand for ir-
rigation and a large percent of industrial, municipal, and
domestic supplies. The total ground-water withdrawal was
9.7 million cu m/d (2.6 bgd) in 1970, 82 percent of which
was used for irrigation. Ground-water withdrawal in the
major drainage basins of Idaho is shown in Table 5. Ground-
water use in Idaho is the highest of all states within the
project area with total ground-water pumpage more than 25
percent larger than in Colorado. Recent trends in ground-
water development suggest a decline in the rate of construc-
tion of new irrigation wells and an increase in the number
of wells drilled for domestic and recreation home purposes,
indicative of urbanization of former farmland. 26)
Problems involving ground water in the state are water-right
conflicts, reduced streamflow resulting from large-scale
ground-water development, waterlogging as a result of irri-
gation, water quality deterioration from agricultural runoff,
and the discharge of industrial and municipal wastewaters.
Concern is also being expressed about liquid waste disposal
practices at the National Reactor Testing Station (NRTS).
Ground-water studies in the state are carried out by the
U. S. Geological Survey in cooperation with the Idaho Depart-
ment of Water Administration, by the Water Resources Insti-
tute at the University of Idaho, the Idaho Bureau of Mines
and Geology, and the U. S. Atomic Energy Commission.
In this report, the state has been divided into the follow-
42
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Table 5. IDAHO. ANNUAL WITHDRAWAL AND USE OF GROUND WATER IN MAJOR DRAINAGE BASINS.
25)
CO
Bear River
1965
Purpose million m^ 1 ,
Irrigation
Hectares (acres)
irrigated (1,000)
Withdrawal 185.0
Consumptive use
Industrial (self-supplied)
Withdrawal 2.8
Consumptive use 0.1
Public Supplies
Persons served (1,000)
Withdrawal 5.6
Consumptive use 1 . 1
Rural -Domestic
Persons served (1,000)
Withdrawal 0.3
Consumptive use 0.1
Stock
Withdrawn and used 0.4
Total withdrawal 190
Total consumptive use
Basin
000 acre -feet
150
-
2.3
0.1
4.5
0.9
0.2
0.1
0.3
160
-
Panhandle Basins a'
1970
million m^ 1 ,000 acre-feet
40
21
10
0
6
1
3
1
0
620
250
4.5(11)
.7 33
.0 17
.6 8.6
.5 0.4
23
.8 5.5
.4 1.1
23
.2 2.6
.6 1.3
.2 0.12
50
20
Upper
million n
Snake River Basins
1970
n^ 1 ,000 acre -feet
307.6 (760)
2,960.4
1,603.6
76.5
3.8
61.7
12.3
17.3
8.6
7.4
3,120
1,640
2,400
1,300
62
3.1
180
50
10
124
14
7
6
2,530
1,330
a) Kootenai, Pend Oreille and Coeur d'Alene River Basins.
-------
Table 5 (continued). IDAHO. ANNUAL WITHDRAWAL AND USE OF GROUND WATER IN MAJOR DRAINAGE BASINS
>ti
J\J
-------
ing geographic areas: Kootenai and Pend Oreille River ba-
sins, Spokane-Coeur d'Alene River basin, Clearwater and
Palouse River basins, Salmon River basin, Snake River basin
and its various subdivisions, and the Great Basin. The lo-
cation of principal aquifers and normal depths of wells are
shown on Figure 9, and the range in yields of wells is in-
dicated on Figure 10.
Kootenai and Pend Oreille River Basins -
The Kootenai and the Pend Oreille Rivers discharge large
flows of water, much of it originating in Montana and Canada,
A sizable underflow of ground water takes place along the
Idaho-Washington border. 7) The glacial deposits in the val-
leys contain great quantities of ground water but use is
relatively small. Springs or streams are tapped for water
supply by most municipalities. In the upland area, domestic
wells are drilled into the crystalline bedrock.
Spokane-Coeur d'Alene River Basin -
Large quantities of ground water are available from the gla-
cial outwash deposits in the lowlands and in the river val-
leys. Studies on the Rathdrum Prairie indicate that more
than 123 million cu m or 100,000 acre-ft of ground water
flows annually into Washington through permeable sand and
gravel deposits. 28) A portion of this ground water is be-
lieved to represent seepage from Pend Oreille Lake in the
adjacent river basin. Damming .of this lake has caused a
water-table gradient of 30 to 80 cm/km (1.5 to 4 ft/mi) to
the Washington state line, increasing to 60 to 240 cm/km (3
to 12 ft/mi) westward to Spokane. 29)
Ground-water levels on the Prairie are low, reflecting the
high permeability of the gravel deposits. In spite of this,
a considerable amount of ground water is used for industrial
and municipal supply- Sprinkler irrigation from wells is
also increasing.
Ground water in the Coeur d'Alene River basin is available
from alluvial deposits varying in thickness from 0.3 to
100 m (one ft to several hundred ft). Most of the domestic
supply comes from springs and creeks. 7) Waste from mining
operations and ore processing along the South Fork portion
of the basin has resulted in considerable surface-water pol-
lution.
Clearwater and Palouse River Basins -
The Columbia River Group basalt, associated sedimentary
45
-------
AQUIFERS
Alluvial sand and gravel
including glacial outwash
COfUf
Chiefly basalt of the Snake River Group 15~170 50~ 50°
Volcanic and
sedimentary rocks
DEPTH OF WELLS
Meters Feet
15-100 50- 300
30-300 100-1,000
70-500 200-1,500
200 KM.
27)
Figure 9. Idaho - Major aquifers and depths of wells . '
-------
Yield
NORTH
gpm
Unknown
V///A 3- 30
30-120
120
200 KM.
Figure 10. Idaho - Range in yields of wells. ^
47
-------
rocks, and alluvium are the principal aquifers in these ba-
sins. Ground water is used for domestic, public, and indus-
trial supply, but little information is available.
The Moscow Basin, an area of 150 sq km (60 sq mi) drained by
the South Fork of the Palouse River, has potential water-
supply problems because of rapid population increase.
Ground water in the Moscow area is available from unconsoli-
dated deposits and sands in the Latah Formation and from in-
terbedded Columbia River basalt flows. The upper sediments
are under water-table conditions, and the deeper aquifers
are divided into an upper, middle, and lower artesian zone.
Heads in the upper artesian zone declined 30 m (100 ft) over
the years but are now rising due to decreased pumpage. 30,31)
Prior to the early 1960's, all public supplies were obtained
from the upper artesian zone, but since then pumpage has
shifted to the deeper zones.
Ground-water pumpage in the Moscow Basin averaged about 88
1/s (2 mgd) during 1961-65 and is expected to double in the
future. Recharge to the ground-water system is estimated to
be about one-tenth of ground-water pumpage. Mathematical
model studies of the aquifer, however, indicate that ground
water in storage should meet water requirements for the next
50 to 100 years, and artificial recharge could prove to be a
partial solution to future water problems.
In the upland areas t underlain by crystalline rocks of Pre-
cambrian (Belt Supergroup) and Cretaceous age, wells drilled
for domestic supply yield only small quantities of water. 32)
Salmon River Basin -
The Salmon River and its tributaries cover a large portion
of central Idaho. Principal aquifers are alluvial deposits
in the river valleys and volcanic and associated sedimentary
rocks. Water requirements are met mostly by tapping surface
water, and as a result, ground-water resources are largely
undeveloped.
Few ground-water studies have been made. In the Pahsimeroi
River basin, alluvial sand and gravel deposits may be 1,000
m (3,000 ft) thick according to geophysical studies. The
maximum thickness penetrated by wells is 120 m (350 ft).
Irrigation wells tapping the alluvial aquifer yield as much
as 240 1/s (3,850 gpm), and specific capacities range from
20 to 40 1/s/m (100 to 200 gpm/ft). 33)
Some 11,000 ha (27,000 acres) of land are irrigated; 9,900
ha (24,500 acres) by surface water and the remainder by
48
-------
ground water. Surface-water diversions in 1971 totaled 148
million cu m (120,000 acre-ft), and some 1.2 million cu m
(930 acre-ft) of ground water was pumped. Other ground-
water use, mostly for domestic purposes, is insignificant.
Snake River Basin -
About 86 percent of the population of the state is located
in the Snake River basin, the largest in Idaho. Within the
basin and its tributary valleys, almost 1.4 million ha (3.4
million acres) of agricultural land are irrigated with Snake
River water. About 18.5 to 24.6 billion cu m (15 to 20 mil-
lion acre-ft) of surface water is diverted for irrigation.
The river is an important resource for hydro-electric power
generation and for navigation. Flow is regulated by numer-
ous dams and reservoirs, and total storage capacity of res-
ervoirs is some 12.3 billion cu m (10 million acre-ft).
Some 20 power and multi-purpose dams are presently operating,
under construction, or authorized.
Ground water in the Snake River basin supplies over 70 per-
cent of the water needs of 200 municipal water-supply sys-
tems and about 100 industrial plants. Some 1.4 million cu
m/d (360 mgd) of water are used for these purposes. In 25
years, the joint municipal-industrial demand will increase
to over 3.8 million cu m/d (1,000 mgd). Ground-water condi-
tions in the main river valley and in several tributary
river basins have been studied. Because local hydrogeologic
conditions vary from place to place, these regions will be
discussed separately. The various ground-water areas within
the basin are shown on Figure 11.
The Weiser and Payette River basins are located in the west-
central portion of the Snake River drainage basin. Ground
water is obtained from the Columbia River Group basalt and
from valley-fill deposits. Ground water is used for drink-
ing and industrial supply and for irrigation. In 1960,
ground-water use for irrigation was 62 million cu m (50,000
acre-ft) in the Weiser Valley and 74 million cu m (60,000
acre-ft) in the Payette Valley. 7)
The Boise-Nampa area in the western portion of the Snake
River basin is undergoing a rapid change due to increased
urbanization. Population rose from 97,800 in 1953 to
134,000 in 1970, and ground-water use has increased consid-
erably. Shallow aquifers are terrace gravels, Quaternary
alluvium, and basalts of the Snake River Group. These for-
mations act as a single hydrologic unit and individual well
yields are high. The Glenns Ferry Formation of the Idaho
Group is the deep aquifer in the area. This unit is com-
49
-------
S .—... u """ "^
CAMAS
PRAIRIE
NATIONAL REACTOR
TESTING STATION
EASTERN
HIGHLAND
MOUNTAIN
HOME
PLATEAU
OWYHEE
UPLAND
Figure 11. Idaho - Ground-water areas of the Snake River Basin. '
0 30 60 KM.
i I I
15 30 Ml.
-------
posed of continental beds of clay, silt, sand, and fine
gravel, and locally contains volcanic ash and lava flows.
Its total thickness is about 600 m (2,000 ft). The aquifer
can be found at relatively shallow depth below much of the
area. The terrace gravels overlying the Glenns Ferry Forma-
tion have a'total thickness of 50 m (150 ft), and the Snake
River Group basalt beds have a maximum thickness of 100 m
(300 ft). Alluvial deposits present in the floodplain have
a thickness of about 17 m (50 ft).
Application of surface water to farmland on the terraces and
floodplain of the Boise River for over 60 years has raised
ground-water levels and has increased the amount of ground
water held in storage. In 1970, only 12,500 ha (31,000
acres) in the Boise-Nampa area were irrigated by ground wa-
ter. Pumpage for irrigation was 115 million cu m (93,000
acre-ft), all obtained from the deep aquifer. The same
aquifer supplied 33 million cu m (26,800 acre-ft) of water
for domestic and stock use and 19 million cu m (15,100 acre-
ft) for industrial use. The shallow aquifer was only used
for domestic and stock use and supplied 13 million cu m
(10,700 acre-ft). 35) The shallow aquifer is recharged
mainly by irrigation returns, and in 1970, this recharge
amounted to an estimated 617 million cu m (500,000 acre-ft)
of water. Most of this water was surface water, but a por-
tion was obtained from irrigation wells tapping the deep
aquifer. This large volume of water applied to the shallow
aquifer has caused chronic waterlogging problems.
In southern Canyon County, permeable sands of the Idaho For-
mation are the principal aquifers with yields of as much as
100 1/s (1,600 gpm) to pumped wells. 36) Perched ground wa-
ter occurs locally- The Snake River Basalt is above the wa-
ter table in most of the area, but where saturated, it
yields water freely. In 1960, some 1,200 ha (3,000 acres)
were irrigated by ground water in the Dry Lake area. Well
depths ranged from 65 to 400 m (200 to 1,200 ft). Yields
vary widely because of variations in lithology and well con-
struction. Upward leakage of artesian water has caused wa-
terlogging south of Melba, and high water-table conditions
and drainage problems occur south of Lake Lowell.
The Owyhee upland in the southwest corner of the state is
drained by the Snake and Owyhee Rivers. Ground water is
available from volcanic rocks, sediments of the Idaho Group,
and valley-fill material; but there are few wells, and
pumpage is small.
The Mountain Home Plateau is a rolling upland plain located
between the Boise Valley and the Snake River valley. Ground
51
-------
water is generally found at depths exceeding 100 m (300 ft)
in the Snake River and Idaho Groups, which consist of alter-
nating basalt and gravel beds. Locally, perched ground wa-
ter is available at shallower depth. Ground water is util-
ized for rural and domestic use, but supplies are considered
insufficient for large-scale irrigation because of the low
rate of recharge. Well development is concentrated in the
Kuna area in Ada County and near the Mountain Home Air Force
Base in Elmore County. Wells in the Kuna area are less than
300 m (1,000 ft) deep and generally yield more than 60 1/s
(1,000 gpm). 37) Yields of wells in the Air Base area range
between 30 and 120 1/s (500 and 2,000 gpm).
Ground water in the Snake River valley from the Oregon state
line upstream to the town of Bliss is obtained from basalt,
the Idaho Group, silicic volcanic rocks and alluvial de-
posits. Unconfined ground water is a minor source of irri-
gation water. In the Bruneau-Grand View area, artesian wa-
ter confined in the volcanic rocks is widely used for irri-
gation, and deep wells yield from 30 to 250 1/s (500 to
4,000 gpm). Pumpage for domestic use and irrigation was
about 2.5 million cu m/d (1,000 cfs) in 1969. Conditions
for large-scale development of ground-water resources are
excellent except in the Bruneau-Grand View area where the
use of artesian water is severely limited by its chemical
quality. In addition, overpumping is causing local water-
level declines. 38)
In Camas Prairie, ctn intermontane basin along the north
flank of the Snake River Plain with an area of about 780 sq
km (300 sq mi), ground water is obtained from alluvial fill
and basalt. Water in the shallow deposits is under water-
table conditions and the water table is less than 3m (10
ft) below the surface. The deeper sand and gravel aquifer
is divided into an upper and lower horizon. These units are
artesian and many of the deeper wells flow. Basalt inter-
fingers with alluvial deposits and is an important aquifer
in the east and southeast. The maximum thickness of the
valley fill is 170 m (500 ft). Irrigation wells tapping
sand and gravel beds yield 30 to 75 1/s (500 to 1,200 gpm).
Wells drilled in basalt will yield 120 to 190 1/s (2,000 to
3,000 gpm).
Ground water is used for domestic, stock, and municipal sup-
plies and for irrigation. Total pumpage in 1960 was about
2.5 million cu m (2,000 acre-ft). Calculations indicate
that some 14.8 million cu m (12,000 acre-ft) of ground water
can safely be withdrawn each year. Large-scale development
of ground water would lower the water table considerably and
would affect the present practice of subirrigation. 39)
52
-------
The Wood River basin, located east of the Camas Creek basin
and north of the Snake River Plain, is drained by the Big
Wood and Little Wood Rivers. Ground water is found in flu-
vioglacial deposits that reach a thickness of over 100 m
(300 ft) in places. Some wells in the Carey area tap the
basalt aquifer. Water levels are generally less than 13 m
(40 ft) below the surface. Artesian sand and gravel zones
in the Big Wood River valley are found 40 to 50 m (125 to
150 ft) below land surface. Ground water is used for domes-
tic, stock, municipal and irrigation supplies. In 1960,
some 43 million cu m (35,000 acre-ft) was pumped for irriga-
tion.
The basins of Big Lost River, Little Lost River, and Birch
Creek lie along the northern edge of the Snake River Plain
east of the Little Wood River basin. There is no surface-
water runoff in these basins, as all water infiltrates into
alluvial deposits and basalt (lower Big Lost River valley)
and drains southward toward the Snake River. The alluvial
deposits near the mouth of the Big Lost River valley are
over 100 m thick and transmit large quantities of ground wa-
ter, estimated at several hundred million cu m/yr. The wa-
ter table is generally close to the surface, and in some
areas, the occurrence of ground water is complex because of
multiple perched aquifers resulting from irrigation and per-
colation (Arco, Butte City). Moderately large to large
yields can be developed from wells 30 to 65 m (100 to 200
ft) deep. Specific capacities in the Arco area, located to
the east of the mouth of the Big Lost River valley, range
from 40 to 80 1/s/m (200 to 400 gpm/ft).
Wells drilled in the Little Lost River valley are generally
less than 50 m (150 ft) deep and are mostly used for irriga-
tion. Yields range from 30 to 60 1/s (500 to 2,500 gpm) .
Little information on ground water is available regarding
the Birch Creek basin, but underflow is estimated at 86 mil-
lion cu m (70,000 acre-ft) per year. Ground-water withdraw-
al in 1960 was about 62 million cu m (50,000 acre-ft) in the
Big Lost Valley and 49 million cu m (40,000 acre-ft) in the
Little Lost Valley. Conditions for large-scale development
of ground-water resources are excellent; however, conflicts
over surface-water rights could arise in places.
In the Mud Lake basin at the northeast end of the Snake
River Plain, the principal aquifer is the Snake River basalt
and associated cinder beds. Hundreds of wells are used to
irrigate many thousands of hectares of land. The basalt is
extremely permeable, and well yields range from 125 to 570
1/s (2,000 to 9,000 gpm) with drawdowns of less than one m.
53
-------
North of Mud Lake, the basalt is at the surface, and the
land is not suitable for irrigation. Well fields drilled in
this area discharge water into canals and distribute the wa-
ter to irrigated land to the west and southwest. Ground wa-
ter moves from the Mud Lake area toward the Snake River
Plain. This underflow is estimated at over 370 million cu m
(300,000 acre-ft) per year. Ground water is also used for
domestic, stock, and municipal supplies. Total pumpage in
1960 was about 370 million cu m (300,000 acre-ft). /)
In the Twin Falls district on the southwest side of the
Snake River Plain, ground water is obtained from basaltic
and silicic rocks and from sand and gravel beds. The water
is at shallow depth near the mountains but is deeper than
165 m (500 ft) near Salmon Falls Creek. Ground water is
used extensively for public supply and also for domestic,
stock, and irrigation. The total pumpage in 1960 was about
43 million cu m (35,000 acre-ft). Additional supplies of
ground water could be developed. In the Twin Falls tract,
ground-water levels have risen over 30 m (100 ft) as a re-
sult of irrigation with Snake River water. Most of the
wells in this area obtain water for irrigation from shallow
aquifers. 40) Underflow in buried channels in the Salmon
Falls area is at least 31 million cu m (25,000 acre-ft) per
year. 41)
The basins of Dry, Cottonwood, Goose, Rock and Marsh Creeks
are located east of the Twin Falls district on the south
side of the Snake River Plain. Ground-water conditions are
quite variable, but principal aquifers are alluvial deposits,
basalt of the Snake River Group, silicic volcanic rocks, and
limestone. In the Dry Creek area, 250 wells supplied irri-
gation water to about 6,000 ha (15,000 acres) in 1959. Ar-
tesian aquifers are considered fully developed, but more
ground water could be developed from the Snake River ba-
salt. 42)
In the Goose Creek and Rock Creek basins, yields range from
12 to 190 1/s (200 to 3,000 gpm) in the basalt and silicic
rock aquifers, and from 12 to 70 1/s (200 to 1,100 gpm) in .
the alluvial aquifers. Pumping lifts are as high as 150 m
(450 ft). About 430 wells withdrew 228 million cu m
(185,000 acre-ft) of ground water for irrigation in the
1961-1965 period. 43) Total purapage for irrigation in all
areas was about 308 million cu m (250,000 acre-ft) in 1960.
In the Raft River basin in south-central Idaho, the alluvial
deposits form the main aquifer in the central and southern
part of the valley. The basalt of the Snake River Group is
the principal aquifer at the north end. Ground water is
54
-------
used for domestic, stock, and irrigation supply- ") in
1966, about 28,000 ha (69,000 acres) were irrigated partly
or wholly with ground water, and some 290 million cu m
(235,000 acre-ft) of ground water was pumped. The valley
was closed to further ground-water appropriation as of July
1963 because of declining water levels. 45)
Further east, in Oneida and Power Counties, including the
Curlew, Arbon and Pocatello areas, well development is most-
ly for domestic and stock use. About 19 million cu m
(15,000 acre-ft) per year is pumped from a sand and gravel
aquifer in the Curlew valley. 46)
In the Eastern Highlands, that lie to the east and southeast
of the Snake River Plain, ground water is found in alluvium,
basalt of the Snake River Group, and silicic volcanic rocks.
Alluvial aquifers in the lowlands supply large quantities of
water, and well yields range from 30 to 60 1/s (500 to 1,000
gpm). 47) in 1960, some 123 million cu m (100,000 acre-ft)
of ground water was pumped for irrigation, chiefly in the
Michaud Flats, Pocatello, Rigby and Rexburg areas. Ground
water is also used for domestic, municipal, and industrial
supplies.
In the Portneuf River basin, the quantity of ground water
pumped for irrigation was about 37 million cu m (30,000
acre-ft) in 1970. Principal aquifers are alluvial deposits
and basalt beds. 48)
The Snake River Plain, a broad undulating surface of about
26,000 sq km (10,000 sq mi), extends for about 400 km (250
mi) along and mainly north of the Snake River in southeast-
ern Idaho. The Plain is a great structural depression
filled with a series of basalt flows alternating with beds
of pyroclastic and sedimentary materials, which constitute
one of the world's most productive aquifer systems. At the
surface, the boundaries of the aquifer are formed by the
contact with less permeable and complex rock formations sur-
rounding the Plain. At depth, the boundary of the aquifers
is not known, as no well has been drilled through the entire
rock sequence. The aquifer is several hundreds of meters
thick except near the edge of the plain.
The storage capacity of the aquifer is huge and estimated at
hundreds of billions of cubic meters. Water is contained
within interflow zones (between lava flows), clinker open-
ings (formed at lava flow surface when cooling), shrinkage
cracks (resulting from cooling), lava tubes (formed by
liquid lava flowing out beneath solidified crust), and ves-
icles (pores formed by expansion of gases during cooling).
55
-------
These openings are interconnected and make the aquifer high-
ly permeable. Well yields of 120 to 300 1/s (2,000 to 5,000
gpm) are common. Typically, an irrigation well is drilled
for each 65 to 260 ha (160 to 640 acres) of land to be irri-
gated and is pumped at 55 to 225 1/s, (900 to 3,600 gpm). 7)
Centers of population, agricultural development, and water
use are mostly near the Snake River which flows along the
southern and eastern margins of the Plain. Cropland near
the river is practically all irrigated with Snake River wa-
ter while land further from the river is irrigated with
ground water. In 1965, an estimated 600,000 ha (1,500,000
acres) were irrigated - 360,000 ha or 900,000 acres with
surface water and 240,000 ha or 600,000 acres with ground
water. 42,49)
The Snake Plain aquifer also supplies 100 percent of the do-
mestic water needs in the region. 50) Recharge to the aqui-
fer is huge. About 4.9 billion cu m (4 million acre-ft) of
water is recharged to the aquifer annually as a result of
irrigation from surface-water sources while 1.4 billion cu m
(1,100,000 acre-ft) of the ground water pumped returns to
the aquifer. 49)
The Snake Plain aquifer is recharged by precipitation, in-
filtration from irrigation water, seepage from streams, un-
derflow from tributary basins, and wastewater introduced
into drain wells. Ground-water flow is toward the Snake
River and discharges along the valley in large springs.
Some 70 cu m/sec (1.8 million acre-ft/yr) of ground water
flows into the Snake River in the stretch between the Black-
foot River and the Raft River, and some 185 cu m/sec (4.7
million acre-ft/yr) enters the river between Milner Dam and
Bliss. 7)
In spite of the fact that the Snake Plain aquifer has been
studied extensively in the last 70 years, many uncertainties
still remain due to complex hydrogeologic conditions. Only
tentative evaluation of aquifer characteristics is possible.
The use of modeling to study the aquifer is now in process.
50)
The National Reactor Testing Station (NRTS) covers 2,300 sq
km (890 sq mi) of desert and basalt fields on the eastern
Snake River Plain. Numerous ground-water investigations
have been made in this area by the U. S. Geological Survey
and the Atomic Energy Commission. Most of the ground water
contained in the Snake Plain aquifer below the site origi-
nates as underflow from the northeastern part of the Plain
and from adjacent drainage areas to the west and north.
56
-------
This estimated underflow beneath the NRTS is 78 cu m/sec,
equivalent to 4.7 x IdH gal/yr. 51) The ground water moves
southward through the aquifer and discharges through springs
along the valley of the Snake River near Hagerman.
The rocks below the NRTS site consist of about 1,600 m
(5,000 ft) of basaltic volcanic rock interbedded with allu-
vial sediments. Interbedded sedimentary rocks within the
basalt act as aquifers or aquicludes depending on their per-
meability. Fractures, cavities, and lava tubes form passage-
ways for ground-water movement. Floodplain deposits vary-
ing in thickness from a few cm to over 20 m (50 ft) are
present over most of the Station. These deposits consist
mostly of coarse sand and gravel and are highly permeable.
The depth to water within the NRTS boundaries ranges from
65 m (200 ft) in the northeast to 270 m (900 ft) in the
west-southwest. 52)
Water for NRTS facilities is obtained from 24 wells tapping
the Snake Plain aquifer. The water is used for reactor
cooling, washing, chemical processing, and drinking. Pump-
age for all facilities in 1970 was 10 million cu m (2.6 bil-
lion gallons) or roughly 310 1/s (4,900 gpm). About half of
this amount, 4.5 million cu m or 1.2 billion gallons, was
returned to the ground through wells and ponds. 51)
Much additional ground water can be pumped in the Snake
River Plain, but increased consumptive use may cause a de-
crease in streamflow and may conflict with established water
rights. Studies of artificial recharge of ground water are
underway. 49)
Great Basin -
An area of several hundred sq km of southeasternmost Idaho
forms part of the Great Basin drainage system. The area is
drained by the Bear and Malad Rivers which flow southward
into Utah. Ground water is encountered in alluvium, sedi-
mentary rocks, and in basalt of the Snake River Group.
Ground-water use for irrigation was 148 million cu m
(120,000 acre-ft) in 1960 and applied to 16,000 ha (40,000
acres) of land. Ground water is also used for domestic,
stock, municipal, and industrial use. Well yields are as
high as 155 1/s (2,500 gpm) from the alluvium and 220 1/s
(3,500 gpm) from the basalt. 53)
Montana
Montana, the largest state within the project area, is a re-
gion of mountains, intermontane valleys, and plains. Pre-
57
-------
cipitation averages about 380 ram (15 in) but varies from
1,140 mm (45 in) or more in the Rocky Mountains to less than
250 mm (10 in) in the south-central Plains area. The east-
ern three-fourths of the state is part of the Great Plains
and is drained by the Missouri and Yellowstone Rivers and
their tributaries. The region west of the Continental Di-
vide is drained by the Kootenai and Clark Fork Rivers and
their tributaries. The total river flow leaving the state
is estimated at 139 cu hm/d (36 bgd), or 41 million acre-ft
per year. Of this amount, some 27 cu hm/d (8.1 million
acre-ft) is received from Canada in the Kootenai and Flat-
head Rivers and 16 cu hm/d (4.8 million acre-ft) enters the
state from Wyoming in the Yellowstone and Bighorn Rivers.
Surface-water runoff differs sharply from west to east. In
the mountainous western portion the average annual runoff
varies from 125 to 1,000 mm (5 to 40 in), but in the plains
it is less than 25 mm (one in), except for isolated mountain
ranges. In the Plains area, rainfall is sufficient only for
stock raising and dry farming. The Missouri and Yellowstone
Rivers and principal tributaries are extensively used for
irrigation, and the chemical quality of the rivers is de-
teriorating. 54)
Only a small part of the available water resources is used
within the state. The population is roughly 700,000, and
the total water use of 1.2 million cu m/d (308 mgd) in 1970
for public, rural, and industrial supplies is low compared
to that of the other project states. Irrigation is the
major water use. In 1970, some 2.9 million cu m (7.7 bil-
lion gallons) per day of water was used to irrigate 890,000
ha (2.2 million acres).
Serious conflicts between agricultural and potential indus-
trial water users are occurring in eastern Montana. Devel-
opment of major coal reserves in the basin is planned, and
coal and utility companies have requested more than 4.1
billion cu m (3.3 million acre-ft) per year of surface water.
The Yellowstone River has an average annual flow of about
11.1 billion cu m (9 million acre-ft) and a low flow during
dry years of about 3.2 billion cu m (2.6 million acre-ft).
Existing water rights for irrigation amount to 2.8 billion
cu m (2.3 million acre-ft). Thus, the industrial require-
ments cannot be met. 55) in order to determine water allo-
cations, a three-year ban on the issuance of water permits
in the Yellowstone River basin was put into effect in March
1974. In western and central Montana mountain valleys,
there is a noticeable shift of land and water resources from
agricultural to recreational-residential uses as land is
developed. 56)
58
-------
Because of the readily available surface-water sources in
most areas of the state, ground water plays a minor role.
Only 2 percent of the total water used in the state is ob-
tained from wells, mostly for public, rural, and industrial
supplies. Total ground-water use in 1970 was 564,000 cu m/d,
the lowest of the six states. All indications are that the
use of ground water will increase sharply in future years.
Enormous quantities of water stored in deep aquifers can be
developed for use.
Principal aquifers are unconsolidated valley-fill and gla-
cial deposits, and permeable sedimentary rocks. Buried val-
leys containing sand and gravel deposits are numerous. 57)
The Plains are underlain by gently eastward-dipping sedi-
mentary rocks of Cenozoic, Mesozoic, and Paleozoic age, in-
terrupted by structural basins and domes. The area roughly
north of the Missouri River is mantled by glacial drift.
The bedrock geology and principal preglacial drainage
courses are shown on Figure 12. The ground-water potential
of major unconsolidated aquifers is indicated on Figure 13.
Some 42,300 water wells were inventoried in the state in
1967; of these, about 38,800 were utilized for domestic and
stock use (see Table 6). The quality of ground water is
generally excellent to good in western Montana and good to
poor in the eastern part of the state.
The U. S. Geological Survey, the Montana Bureau of Mines and
Geology, and the Montana Water Resources Board are the prin-
cipal agencies that have made ground-water studies in the
state. In recent years, the Montana University Joint Water
Resources Research Center has also carried out some ground-
water investigations.
Unconsolidated Aquifers -
Alluvium, terrace deposits, and glacial deposits form excel-
lent aquifers. Alluvial fill in intermontane valleys in the
west and deposits along the principal rivers in the central
and eastern portion of the state are capable of yielding
large quantities of water to wells. Some 35 major regions
or valleys underlain by one or more unconsolidated aquifers
have been identified. 57) The permeable thickness of these
unconsolidated deposits ranges from 7 m (20 ft) to over 100
m (300 ft), and the saturated thickness ranges from 3 m (10
ft) to 70 m (200 ft). Valley aquifers are not thick, 3 to
10 m (10 to 30 ft), but are highly permeable and generally
in hydraulic connection with the adjacent river.
Principal areas of actual and potential ground-water devel-
59
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CD
O
0 50 100 KM.
I H 1—'
O 25 50 Ml.
*S?J^] Crystalline Rock
| Sedimentary Rock
•*^* Preglacial Drainage Coursi
Figure 12. Montana - Bedrock geology, major rivers, and pre-glacial drainage courses.
-------
25 50 Ml.
j Wells yielding 60 l/s (1,000 gpm)
or more generally possible.
[Wells yielding from 15-60 l/s
(250-1,000 gpm) generally possible.
1. Deer Lodge Valley
2. Bitterroot Valley
3. Kalispell Valley
4. Missoula Basin
5. Jefferson Valley
6. Beaverhead Valley
7. Big Hole Basin
8. Madison Valley
9.
10.
11.
12.
13.
14.
15.
16.
GallaHn Valley
Townsend Valley
He lena Val ley
Butte
Tobacco Plains
Camas Prairie
White Sulphur Springs 23
Lower Sun Valley 24
17.
18.
19.
20.
21.
22.
Missouri Va I ley
Musselshell Val ley
Big Sandy - Laredo
Northern Blaine County
Yellowstone Valley
Clarks Fork Valley
Rock Creek Valley
Bighorn Valley
Figure 13.
12.7}
Montana - Ground-water potential of major unconsolidated aquifers.
-------
Tabled. MONTANA. USE OF WATER WELLS, 1967.
Use Number of Wells
Public Supply 608
Domestic 12,977
Irrigation 1,417
Industrial 402
Stock 14,846
Domestic and Stock 10,945
Commercial 293
Air conditioning, dewatering, fire protection 42
Institutional 144
Unused 192
Unknown 446
Total: 42,312
62
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opment from unconsolidated aquifers in western Montana are:
Deer Lodge Valley, Bitterroot Valley, Kalispell Valley, Mis-
soula Basin, Jefferson and Beaverhead Valleys, Big Hole Ba-
sin, Madison River valley, Gallatin Valley, Townsend Valley,
Helena Valley, Butte area, Tobacco Plains, Camas Prairie,
White Sulphur Springs area, and the Lower Sun River valley.
In eastern Montana the principal areas are: Missouri River
valley, Musselshell River valley, Big Sandy-Laredo area,
northern Elaine County, Yellowstone Valley, Clarks Fork and
Rock Creek Valleys, and the Bighorn Valley. Potentially
productive deposits of permeable and saturated sand and
gravel beds occur in drainage channels of the former Mis-
souri River system.
In the Deer Lodge Valley, a structural basin filled with
over 1,600 m (5,000 ft) of unconsolidated material of Ter-
tiary and Recent age, ground water is pumped by more than
225 wells. Well yields range up to 60 1/s (1,000 gpm). The
aquifer consists of sand and gravel beds within the upper
section of the valley fill. Deeper artesian aquifers are
also present. Agriculture and ore processing are the prin-
cipal industries. Ground-water use for industrial, munic-
ipal, stock, domestic, and irrigation was 8.6 million cu m
(7,000 acre-ft) in 1967. Evapotranspiration and pumpage
cause a seasonal lowering of the water table of as much as
3 m (10 ft), but each spring, the Clark Fork River, irriga-
tion seepage, and infiltration from precipitation replenish
the ground-water reservoir. 58)
The Bitterroot Valley, an intermontane basin located south
of Missoula, contains extensive saturated alluvium and Ter-
tiary deposits that are tapped by over 85 wells. Average
saturated thickness of the aquifer is some 13 m (40 ft), and
well yields range from 15 to 60 1/s (250 to 1,000 gpm).
Most of the ground water is used for stock and domestic pur-
poses. About 20 wells irrigate 480 ha (1,200 acres). Large
amounts of additional ground water can be developed as ade-
quate recharge is available. 59,60)
The Kalispell Valley in northwestern Montana is an inter-
montane basin with several aquifers of Pleistocene and Re-
cent age within the upper 200 m (600 ft) of the valley fill.
Principal aquifers are a deep artesian, a shallow artesian,
and a floodplain gravel formation. These aquifers are tap-
ped by more than 450 wells that range in depth from 10 to
150 m (30 to 450 ft) and in yield from 0.3 to 190 1/s (5 to
3,000 gpm). The floodplain gravel aquifer is about 10 m
(30 ft) thick and yields 1.4 million cu m (1,100 acre-ft) of
water per year. Its average transmissivity is 1,400 sq m/d
(1,100,000 gpd/ft). 61) A saturated and confined zone of
63
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sand and gravel occurring throughout the valley is termed
the deep artesian aquifer. It is tapped by more than 200
wells (some flowing), ranging in depth from 30 to 160 m (100
to 500 ft). Development of this deep sand and gravel zone
is accelerating because it is little affected by drought and
because of poor water quality in shallower aquifers.
Alluvial deposits within the Clark Fork and Ninemile Valleys
in the Missoula Basin are tapped by more than 275 wells,
mostly for domestic and stock supplies. The aquifer has an
average thickness of 65 m (200 ft), and well yields are re-
ported to be as high as 315 1/s (5,000 gpm). Pumpage was 30
million cu m (24,000 acre-ft) in 1963. 62)
Alluvial deposits along the Jefferson River, its upstream
extension (the Beaverhead River), and major tributaries in
southwestern Montana contain relatively thin but important
aquifers. Average thickness is 6 to 8 m (20 to 25 ft), and
well depths range from 3 to 55 m '(10 to 170 ft). Most well
yields are in the 0.3 to 2 1/s (5 to 30 gpm) range, but some
large-capacity wells yield 95 1/s (1,500 gpm). Ground water
is mostly used for stock and domestic purposes. In the
Beaverhead River valley, some ground water is used for irri-
gation.
The ground-water potential of the alluvial deposits along
the Big Hole River, a tributary to the Jefferson River, is
excellent. The alluvial fill is some 50 m (160 ft) thick
with an average saturated thickness of 10 m (30 ft). Most
wells tapping the aquifer are small-capacity domestic and
stock wells; however, large yields in the 15 to 60 1/s (250
to 1,000 gpm) range are feasible. Similar conditions pre-
vail in the Madison River valley. Here the alluvial aquifer
is only tapped by stock and domestic wells, but potential.
well yields are estimated at 60 1/s (1,000 gpm).
In the Gallatin Valley, an intermontane basin, ground-water
resources are largely undeveloped. More than 1,100 wells,
ranging in depth from 3 to 30 m (10 to 100 ft), tap the
alluvium beneath the valley floor and the alluvial fan de-
posits chiefly for domestic and stock purposes. Over 40,000
ha (100,000 acres) are irrigated by surface water. Yields
of some irrigation wells reach 120 1/s (2,000 gpm). Exces-
sive recharge has caused waterlogging in an area covering
some 7,000 ha (17,000 acres). 63)
The Townsend Valley in west-central Montana is underlain by
permeable alluvium over 30 m (100 ft) thick. Over 500 wells
tap this aquifer, chiefly for stock and domestic use. Irri-
gation is mostly by surface water, and some 2,800 ha (7,000
64
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acres) are waterlogged.
64)
The Helena Valley, a small intermontane basin northeast of
the capital city of Helena, is underlain by alluvial de-
posits and fine-grained lake sediments. Principal aquifers
are thick alluvial fans and permeable beds in the lake de-
posits. Some 120 wells ranging in depth from 3 to 130 m (10
to 400 ft) tap the aquifers. Most of the wells are for
stock and domestic use. Yields range from 10 to 20 1/s (150
to 300 gpm), but yields up to 60 1/s (1,000 gpm) would be
possible. A large area of the alluvium in the valley is
fully saturated and over 3,200 ha (8,000 acres) are water-
logged. This situation is caused by irrigation on the
higher lands of the valley- 65)
In the vicinity of Butte, the principal aquifer is the allu-
vium in a valley south of the city. The aquifer covers 37
sq km (23 sq mi), is relatively thick, and yields sufficient
water for domestic and stock wells. Although most of the
water used in the area is from surface-water supplies, the
number of domestic wells is increasing. 66)
The Tobacco Plains area in northwestern Montana is underlain
by alluvial deposits of over 30 m (100 ft) in thickness.
Ground water from sand and gravel zones is used for munici-
pal, domestic, and stock supplies. Potential well yields
are estimated between 15 and 60 1/s (250 and 1,000 gpm) .
The present ground-water use is small, but the area has ex-
cellent ground-water potential.
Another area in northwestern Montana with an excellent poten-
tial for further ground-water development is Camas Prairie
valley. Alluvial deposits are tapped by water wells that
yield 12 to 30 1/s (200 to 500 gpm) and range in depth from
3 to 25 m (10 to 75 ft). Pumpage is small and mainly for
stock and domestic use. About 120 ha (300 acres) of land
are waterlogged.
In the White Sulphur Springs area, permeable alluvial de-
posits along the Smith River form the principal aquifer.
Ground water is chiefly used for stock and domestic use, but
there is some irrigation with ground water. Yields of over
60 1/s (1,000 gpm) are reported from wells completed in sand
and gravel deposits in buried stream channels. 67)
Alluvial deposits along the lower Sun River, a tributary of
the Missouri River at Great Falls, form an excellent aqui-
fer. Yields of existing wells range from 0.3 to 5 1/s (5 to
60 gpm), but potential well capacities are estimated at 15
to 60 1/s (250 to 1,000 gpm).
65
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In eastern Montana, there are fewer areas with extensive and
thick unconsolidated aquifers. One of the most important is
the buried pre-glacial channel between the Missouri River
and the Milk River at Havre and its eastward continuation
along the Milk River and the Missouri River. In the lower
Marias area the~ sediments in the channel are some 120 m
(400 ft) thick. Aquifers within these channel deposits are
little explored but have a high ground-water potential. 68)
Over 200 stock and irrigation wells use water from the allu-
vial aquifer in the Big Sandy-Laredo area.
In Elaine County, the valley fill of the pre-glacial Mis-
souri River has a maximum thickness of about 60 m (200 ft).
Alluvial deposits along the Milk River are tapped by a small
number of stock and domestic wells. Further eastward, in
the Missouri River valley, the alluvium bordering the river
reaches a thickness of 40 m (130 ft) in places. Permeable
sand and gravel beds yield large quantities of water to over
200 wells. Well depths range from 3 to 60 m (10 to 200 ft),
and individual well yields range from one to 40 1/s (15 to
650 gpm).68) in northern Elaine County, north of the Milk
River valley, a large elevated plateau (Big Flat) is covered
by glacial till underlain by a thick sand and gravel aquifer
of Tertiary age called the Flaxville Formation. This forma-
tion, up to 25 m (75 ft) thick, is very productive and
yields up to 75 1/s (1,200 gpm) to large-capacity wells. 69)
Alluvial deposits along the Musselshell River in Wheatland,
Golden Valley, and Musselshell Counties are tapped by over
100 stock and domestic wells. Thickness of the permeable
alluvium is some 7 to 10 m (20 to 30 ft). Some wells yield
30 1/s (500 gpm) but most have a small capacity. 67,70)
Along the Yellowstone River there are several sections where
the alluvial deposits are capable of yielding 12 to 60 1/s
(200 to 1,000 gpm) to wells. These areas include the sec-
tion from Park County to Forsyth in Rosebud County, down-
stream of Miles City, and from Glendive to the North Dakota
state line. In the Miles City stretch, some 120 wells rang-
ing in depth from 3 to 30 m (10 to 100 ft) pump water from
the alluvium. The water is used chiefly for stock and domes-
tic purposes. Potential yields of 15 1/s (250 gpm) are pos-
sible near Miles City. From Terry to Glendive there are
over 325 small-capacity wells in the alluvial aquifer.
Yields of 15 to 30 1/s (250 to 500 gpm) are obtained near
Terry. Waterlogging of irrigated tracts is prevalent in
this region. 71,72) The largest ground-water development in
the Yellowstone River valley is downstream of Glendive,
where more than 300 wells obtain water from the alluvial de-
posits. The water is used chiefly for stock, domestic, and
66
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municipal purposes.
Along Clarks Fork and Rock Creek (tributaries of the Yellow-
stone River), the alluvial aquifer is widely used for stock
and domestic supplies. Some 600 wells yielding from 0.6 to
18 1/s (10 to 300 gpm) pump about 6 million cu m (4,700
acre-ft) of water per year. Some water is used for indus-
trial purposes.
In the lower Bighorn Valley and the Lower Little Bighorn
Valley, some 500 wells use water from the alluvium for stock
and domestic purposes. Yields of 10 to 20 1/s (several hun-
dred gpm) are possible in some areas. Waterlogging is wide-
spread in both valleys. 73,74)
Bedrock Aquifers -
Many rock formations are water-bearing, but because of com-
plex geologic conditions not all formations are found in any
given area. Well depths, aquifer thickness, yield, and wa-
ter quality vary widely from region to region. Major bed-
rock aquifers are the Fort Union Formation, the Hell Creek
and Fox Hills Formations, the Judith River Formation, the
Eagle Formation, the Kootenai Formation, the Madison Forma-
tion, the Amsden Formation, the Tensleep Sandstone, and the
Chugwater Formation.
The Fort Union Formation consists of beds of sandstone,
shale, and coal, and has a known maximum thickness of 670 m
(2,200 ft). The formation lies at the surface over vast
areas of eastern Montana and in several areas of south-
central Montana. Within the outcrop area of the formation,
wells 10 to 100 m (30 to 300 ft) deep will encounter ade-
quate supplies of water for stock and domestic use in sand-
stone beds. Coal beds also yield water. Well yields range
up to 4 1/s (60 gpm), with most yields under one 1/s or 15
gpm. The shale zones frequently act as confining beds, and
flowing wells are present in many areas.
The Hell Creek and Fox Hills Formations contain sandstone
aquifers which yield small to medium quantities of water to
wells. The combined thickness of the two formations varies
from 150 to 400 m (500 to 1,200 ft). On the Cedar Creek
anticline in eastern Montana, the two formations form one
single aquifer.
The Judith River Formation consists of sandstones, siltstone,
shale, and lignite beds with a maximum total thickness of
about 120 m (400 ft). Sandstones are the principal water-
yielding units within the formation. The Judith River For-
67
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mation is an important aquifer where it is exposed in north-
central Montana. The formation becomes shaly and less pro-
ductive toward the east. The Parkman Sandstone in Big Horn
County and the Two Medicine Formation in Glacier and Toole
Counties are stratigraphically equivalent to the Judith
River Formation and have similar water-bearing characteris-
tics.
The Eagle Formation, consisting of about 80 m (250 ft) of
sandstone, shaly sandstone, and a lower massive sandstone
member (Virgelle Sandstone), is an excellent aquifer. Mod-
erately large yields up to 16 1/s (250 gpm) can be obtained
from this formation. A few wells flow at rates up to 5 1/s
(75 gpm). The formation "shales out" to the east.
The Kootenai Formation (part of Dakota Sandstone aquifer
system) consists of 120 to 150 m (400 to 500 ft) of shale
and sandstone. A basal sandstone about 30 m (100 ft) thick
is an excellent aquifer, as are other sandstone beds in the
formation. Most wells tapping the Kootenai yield from 0.3
to 10 1/s (5 to 150 gpm), but flowing wells of 3 to 100 1/s
(50 to 1,500 gpm) are reported in Fergus, Garfield, and Big
Horn Counties.
The Madison Formation consists of 200 to 500 m (700 to 1,500
ft) of limestone of karstic nature in the upper part. It is
a source of a number of large springs in Montana and Wyoming,
and oil tests have produced large flows from the formation.
The limestone is an excellent aquifer in Carbon County where
it lies at a depth of about 300 m (1,000 ft). Potential
well yields are over 190 1/s (3,000 gpm). In Cascade County,
the Madison is found at shallower depth, and well yields
range from 0.3 to 3 1/s (5 to 50 gpm). Much information on
the aquifer stems from oil tests that now produce water by
artesian flow. Ground water from the Madison Formation is
also used for secondary recovery operations in several oil
fields. 75) The limestone is a potential source of large
amounts of ground water.
The Amsden Formation of late Mississippian and early Pennsyl-
vanian age consists of several hundred feet of sandstone,
shale, and cavernous limestone. The aquifer is tapped by
wells in the Judith River basin and Big Horn and Carbon
Counties.
The Tensleep Sandstone of Pennsylvanian age and the Chugwa-
ter Formation of Triassic age both contain aquifers capable
of yielding large quantities of water to wells. However,
few have been drilled in these formations.
68
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Minor sandstone aquifers are found within the thick shale
beds that cover large areas in eastern Montana. The Precam-
brian crystalline rocks in western Montana are capable of
yielding small quantities of water to wells.
Oregon
Oregon is a mountainous state with sharply contrasting cli-
matic and ground-water conditions. -The western third of the
state is occupied by mountains of the Coast Range, the Cas-
cade Range, and the Klamath Mountains. Between the coastal
and the Cascade mountains lies the Willamette Valley, a pre-
dominantly flat alluvial area where most of Oregon's popula-
tion resides. The valley is drained by the Willamette River
which flows northward into the Columbia River.
The Coast and Cascade Ranges and the Klamath Mountains re-
ceive as much as 2,500 mm (100 in) per year of precipitation,
in contrast to the Willamette Valley, which has an average
precipitation of 900 mm (35 in) per year. The Cascades are
composed of permeable volcanic rocks, so that infiltration
of precipitation and resulting recharge to the ground-water
reservoir are high. Infiltration is less in the Klamath
Mountains and the Coast Range which are composed of less
permeable rocks, and most precipitation becomes runoff.
The eastern two-thirds of the state forms part of the Colum-
bia Plateaus and the Basin and Range physiographic provinces.
The Columbia Plateaus cover the eastern and north-central
portions of the state. They are underlain by volcanics and
continental sedimentary rocks. The Basin and Range section
in southeastern Oregon is characterized by block faulted
mountains and internally drained basins. This region is un-
derlain mainly by volcanic rocks. Precipitation east of the
Cascades ranges from 200 to 400 mm (8 to 16 in), except in
the Wallowa Mountains in the northeast corner of the state,
which receives 750 to over 1,000 mm (30 to over 40 in). Ma-
jor rivers draining eastern Oregon are the Columbia, Snake,
Deschutes, John Day, and Grande Ronde.
Runoff in the state is about 430 mm (17 in), equivalent to
some 295 cu hm/d (78 bgd). 7) Most of this high runoff
takes place along the steep slopes of the Coast and Cascade
Ranges and the Klamath Mountains. By contrast, runoff in
most of eastern Oregon is less than 25 mm (one in). Figure
14 shows the major drainage and physiographic features.
Alluvial deposits in the main river valleys and the Columbia
River Group basalt are the two principal aquifers. The
principal ground-water areas are each discussed below.
69
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BASIN AND RANGE
90 Ml.
Figure 14. Oregon - Major drainage and physiographic features.
-------
Their locations and the general availability of ground water
in the state are shown in Figure 15. Although the use of
ground water in the state is still relatively small, in-
creases in irrigation, industrial development, and popula-
tion will result in a sharp increase in the amount of ground
water withdrawn. No serious regional ground-water problems
of either quantity or quality exist, although there is con-
cern about liquid waste disposal practices in the lava ter-
rane of eastern Oregon.
Ground-water investigations in the state are carried out by
the U. S. Geological Survey and the Oregon State Engineer's
office. In recent years, the Water Resources Research In-
stitute at Oregon State University has undertaken some
ground-water studies.
Willamette Valley -
The Willamette Valley is part of a long, narrow lowland, the
Puget-Willamette Trough, which extends northward into the
state of Washington. This basin is filled with sedimentary
and alluvial deposits flanked by marine sedimentary rocks of
the Coast Range and volcanic rocks of the Cascade foothills.
These rocks extend beneath the alluvial deposits and appear
in places above the valley floor. The bedrock floor is ir-
regular so that the thickness of the alluvial deposits var-
ies from place to place. Ridges of volcanic rock extend
across the valley near Salem and Oregon City, dividing the
valley into four sections, namely: southern Willamette Val-
ley, northern Willamette Valley, Tualatin Valley, and the
Portland Basin. 76)
Aquifers in the southern Willamette Valley are terrace de-
posits and alluvium underlain by poorly permeable marine and
volcanic bedrock. Thickness of the valley-fill deposits
ranges from 9 to 40 m (30 to 120 ft). Yields of large-
capacity public-supply wells tapping a sand and gravel aqui-
fer in the Eugene-Springfield area range from 15 to 110 1/s
(several hundred to 1,700 gpm). 77) in the Corvallis-Albany
area, the yields of wells completed in the alluvial aquifer
range up to 50 1/s (800 gpm). 78)
In the northern Willamette Valley, the major aquifers are
the sand and gravel deposits along the floodplain, and the
Troutdale Formation, a thick sequence of mudstone, sandstone,
and conglomerate. Much of the valley surface is covered by
sandy silt, which is 30 m (100 ft) thick in places. Locally,
buried volcanic rocks are good aquifers. In the Molalla-
Salem Slope area, the Troutdale Formation is the principal
aquifer and yields about 19 1/s (300 gpm) to individual
71
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-J
to
:::::: BAKER •*& ;;;:;•
Figure 15. Oregon - Availability of ground water.
128)
Large quantities
generally available
Modest quantities
Small quantities
NORTH
100
200 KM.
50
100 Ml.
-------
wells. Wells tapping the Columbia River Group basalt can
yield about 13 1/s (200 gpm) each. 79) in the Eola-Amity
Hills area near Salem, most wells tap the Troutdale Forma-
tion, which is generally less than 60 m (200 ft) thick.
Well yields range up to 32 1/s (500 gpm). 80) Conglomerates
of the Troutdale Formation and alluvium along the Willamette
River yield as much as 100 1/s (1,600 gpm) to wells in the
French Prairie area, north of Salem. Most wells tapping
alluvial deposits here are less than 15 m (50 ft) deep;
wells in the Troutdale Formation are less than 60 m (200 ft)
deep. 81)
Tualatin Valley, a structural basin formed by downwarping of
the Columbia River Group, contains valley fill, mainly clay
and fine sand but with significant sand and gravel beds.
These deposits have a maximum thickness of 460 m (1,500 ft).
Sand and gravel lenses in the valley fill and basalt form
the principal aquifers. Thousands of wells, most of which
are of small capacity, tap these aquifers. The population
in the valley is increasing rapidly due to its proximity to
metropolitan Portland. 82)
Within the Portland area, ground water is obtained mainly
from the Troutdale Formation, fluvio-lacustrine deposits of
Pleistocene age, and alluvium of Recent age. Locally, the
Columbia River basalt and the Boring lava yield substantial
amounts of water. Overpumping has led to lowered water
levels in the west-side business district of Portland. 83,84)
Medford-Ashland Area -
Sand and gravel beds deposited by the Rogue River and its
tributaries constitute the most productive aquifer in the
Medford area in southwestern Oregon. A maximum yield of 6
1/s (100 gpm) is possible from some wells. Moderate to deep
wells in the region tap the non-marine sedimentary rocks and
volcanic deposits. 85) in the Ashland area, along the Cali-
fornia state line, alluvial deposits are too thin to develop
for water supplies without the possibility of inducing pollu-
tion from the surface, and most wells tap sandstone, shale,
tuff, and conglomerate beds. Yields to wells are in the
range of 0.3 to one 1/s (5 to 15 gpm), sufficient for domes-
tic needs. 86)
Coastal Belt -
Terrace deposits and alluvial sands containing fresh water
are present where rivers flowing out of the Coast Range meet
the Pacific Ocean. Dune and beach sands are present along
some coastal sections and are most prominent near the mouth
73
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of the Columbia River (Clatsop dunelands), near the town of
Florence, and near Coos Bay. Yields of 13 to 19 1/s (200 to
300 gpm) are common in the Coos Bay area where the sand de-
posits are 3 km (2 mi) wide, and have a maximum thickness of
about 60 m (200 ft). Recharge to these sand deposits is
high, over 1,400 mm (55 in) per year, and large ground-water
supplies can be developed without causing sea-water contami-
nation. The sands are virtually the only natural signifi-
cant reservoirs of fresh water along the coast as the older
rocks are relatively impermeable. 87,88)
Cascade Range -
The Cascade mountains are formed of permeable volcanic rocks
and readily absorb water from rain and snow. The mountain
range acts as an important recharge area to rivers and aqui-
fers in both the Willamette Valley to the west and the
Deschutes River basin to the east.
Northeastern Oregon -
This area forms part of the Columbia Plateau, a region under-
lain by basaltic rocks covering more than 130,000 sq km
(50,000 sq mi) in Washington, Oregon, and Idaho*. The thick-
ness of the basalt is 150 to 300 m (500 to 1,000 ft) at the
edge and 1,200 to 1,500 m (4,000 to 5,000 ft) in the central
part of the tri-state region. The rock unit consists large-
ly of layered basalt flows, each 3 to 60 m (10 to 200 ft) in
thickness, with some interbedded sedimentary material. Per-
meable zones, openings, and fractures in the basalt give it
a high transmissivity, and yields of over 60 1/s (1,000 gpm)
are possible in such areas. 89) Ground-water discharge from
the basalt is through numerous springs. There are several
intermontane basins, such as Baker Valley, Burnt River val-
ley, Grande Ronde Valley, and the Umatilla River basin,
where ground-water development has taken place.
In Baker Valley, the major aquifers are alluvium and terrace
deposits that yield moderate to large quantities of water to
wells. 90) Fluvioglacial deposits in the Burnt River valley
are over 300 m (1,000 ft) thick. Well yields are less than
3 1/s (50 gpm), except for areas where wells tap gravel
lenses. Basaltic rocks in this valley yield as much as 60
1/s (1,000 gpm) to wells. 91)
In the Grande Ronde Valley, valley-fill deposits are as
thick as 600 m (2,000 ft). Most of the wells obtain small
to moderate supplies of water from water-table aquifers in
the valley fill and alluvial fan deposits. Moderate to
large supplies of water are obtained from artesian aquifers
74
-------
in the fan alluvium and the Columbia River basalt. 92)
The Umatilla River basin, in which the city of Pendleton and
the town of Hermiston are located, is underlain by alluvial
deposits and basalt of the Columbia River Group. The basalt
is the more productive aquifer, capable of yielding 60 1/s
(1,000 gpm) to wells. 93) The ground water forms tabular
bodies confined within scoriaceous zones of the basalt. Po-
tentiometric-head relations are varied and complex due to
structural complications and compartmentation of the hydrau-
lic system. 94) Sand and gravel beds in the alluvium lo-
cally yield as much as 125 1/s (2,000 gpm) to irrigation
wells, but generally yields are much lower.
Southeastern Plateaus -
The region of Oregon receiving the least precipitation and
recharge is underlain mostly by volcanic rocks of moderate
permeability- Principal aquifers are alluvial sand and
gravel beds in the basin areas and lava flows and pyroclas-
tic rocks that overlie impermeable bedrock. Excessive pump-
age of ground water has caused progressive declines of the
water level in some areas. 95)
Washington
The water resources of the state of Washington are very
large. The two principal mountain ranges in the western
portion of the state - the Cascades and the Olympics - in-
tercept moisture flowing in from the Pacific and cause heavy
precipitation and runoff to occur. Annual precipitation is
as much as 5,000 mm (200 in) in the Olympic peninsula and
averages about 1,800 mm (70 in) in western Washington. By
contrast, the annual precipitation in eastern Washington is
about 500 mm (20 in) per year, and is as little as 130 mm
(5 in) in local arid sections. 71) The annual runoff across
the state varies widely. It is 2,000 mm (80 in) or more in
the coast ranges, 1,000 mm (40 in) in the Cascade Range, and
10 mm (0.5 in) or less in the Columbia Plateaus region.
Total runoff is about 325 cu hm/d (86 bgd). 96) Principal
.rivers are the Columbia and its tributaries, the Snake,
Spokane, Pend Oreille and Okanogan. The Columbia River ba-
sin is one of the most extensively developed river basins in
the country. More than two-thirds of the population lives
in the Puget Trough lowland which is a center of commerce
and industry.
In spite of the large total water supply, problems exist due
to uneven distribution of runoff. In the arid eastern zone
traversed by the Columbia River, the stream bed is far below
75
-------
the plateaus, and surface water is not easily utilized.
Problems related to ground-water mining are beginning to oc-
cur in heavily pumped areas. In the western portion of the
state, the runoff takes place largely during the winter and
flows directly into Puget Sound and the ocean. These fac-
tors cause complex water-management problems. Water-demand
projections for the next 30 years indicate no rapid rise in
irrigation development but a substantial increase in domes-
tic and industrial water demand. 96)
The most important aquifers are the unconsolidated or semi-
consolidated deposits of Quaternary age and the basaltic vol-
canic rocks present in the Columbia Plateau, along with prin-
cipal ground-water provinces (Figure 16). 97,98) Ranges in
well yields are shown on Figure 17. Ground-water supplies
about 12 percent of the state's water needs. In 1970, total
ground-water pumpage was some 3.2 cu hm/d (840 mgd). About
1.1 cu hm/d (290 mgd) of this was used for public supply.
Ground-water investigations in Washington have been con-
ducted by the U. S. Geological Survey and the Washington
State Department of Water Resources (now part of the Depart-
ment of Ecology). In recent years, the State of Washington
Water Research Center in Pullman has studied ground-water
problems and interstate aquifers. 99)
Coast Range Peninsula -
The Coast Range Peninsula zone extends from the Olympic
peninsula in the north to the Columbia 'River in the south.
The mountain region is underlain by fine-grained sedimentary
rocks that yield little water to wells. Unconsolidated
glaciofluvial deposits of sand and gravel along the shore-
line and major streams are the principal aquifers.
Significant ground-water development has taken place in the
Sequim-Dungeness area on the Strait of Juan de Fuca in Clal-
lam County, the coastal zone of Grays Harbor and Pacific
Counties, and the Chehalis River valley. In the Sequim-
Dungeness area, extensive glacial outwash deposits yield
large quantities of water to wells, and irrigation with
ground water is widespread. Wells in this region are less
than 60 m (200 ft) deep and commonly yield more than 13 1/s
(200 gpm). 100) Along the coast north and south of Grays
Harbor, terrace deposits yield moderate amounts of water to
wells and springs. Development of ground-water supplies is
limited to North Beach Peninsula, Tokeland-Westport, and the
area between Point Brown and Moclips. Most of the ground
water is used for domestic purposes, but moderately large
quantities are used for irrigation and frost control of
76
-------
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Ground-water Provinces
Principal Aquifers
Volcanic rocks
1 Coast Range Peninsula
2 Puget Sound
Lewis River
(Columbia River Basalt)
Alluvial, terrace, valley-
fill and glacial deposits
Columbia Plateau
Northeast
Figure 16. Washington - Ground-water provinces and major aquifers.
89,97)
-------
00
Figure 17. Washington -Well yields.
Yield of wells
I Unknown
:;'^-:'-'l\ Less than 3 l/s (50 gpm)
rZ2 3-30 'A (50-500 gpm)
H 30-120 l/s (500-2,000 gpm)
-------
cranberry bogs. 101)
In the Chehalis River valley, wells obtain water from two
distinct alluvial aquifers. An upper aquifer extends to a
depth of 30 m (100 ft), with a deeper water-bearing zone
present below it. Well yields range from 13 to 190 1/s (200
to 3,000 gpm). Ground-water use is mostly for domestic sup-
plies. Increased withdrawal of ground water for industrial
and irrigation supplies is anticipated as the region is
rapidly being developed. 102)
Puget Sound -
The Puget Sound province is an extensive lowland area bound-
ed by the Coast Ranges on the west and the Cascade Range on
the east. Much of the lowland is underlain by glacial and
alluvial deposits with a combined thickness of over 600 m
(2,000 ft) in places. Permeable sand and gravel beds form
the principal aquifers and are widely tapped for public sup-
plies, industrial, irrigation, and domestic use. Most of
the population and industry in the state resides in this
lowland. Ground water is used to supply the city of Olympia
and, in part, the city of Tacoma.
Recharge to the aquifer systems is excellent due to heavy
precipitation and runoff from the flanking mountain systems.
From a regional point of view, only a very small percentage
of this ground-water recharge is being withdrawn, and much
larger use of the ground-water resources in the lowland is
possible. Yields of large-capacity wells are often greater
than 60 1/s (1,000 gpm). Flowing artesian wells are common,
with rates as high as 125 1/s (2,000 gpm).
In the Tacoma area (Pierce County), 35 public-supply systems
use wells to supply water to some 300,000 people. The most
productive Quaternary aquifers are in the Salmon Springs
Drift, the Vashon deposits, and alluvium. Yields of wells
are excellent. Tacoma public-supply wells yield from 50 to
570 1/s (800 to 3,000 gpm).
In the Puyallup River valley, coarse sand and gravel present
from 25 to 45 m (80 to 150 ft) below land surface constitute
the principal aquifer. Yields of wells range up to 150 1/s
(2,400 gpm) and average 18 1/s (285 gpm). 103)
In the Olympia area, ground water is found in abundant
quantities in glacial deposits. Outwash aquifers are over
90 m (300 ft) thick in places, and the yield of public sup-
ply and industrial wells averages over 13 1/s (200 gpm).
Aquifers underlying the alluvium of the Deschutes flood-
79
-------
plain are used for industrial supplies in Tumwater. Some
3,400 wells in this region (Thurston County) withdrew about
12.3 million cu m (10,000 acre-ft) of water in 1964, about
half of which was used for irrigation. 104)
In the area between Tacoma and Seattle (southwestern King
County), about 50 percent of the"population was supplied by
ground water in 1964. About '44.3 cu hm (11,700 million gal-
lons) of ground water was withdrawn during 1962. The main
aquifers are coarse sand and gravel in outwash and alluvial
fan deposits. Along Puget Sound, well yields of 6 to 30 1/s
(100 to 500 gpm) are common, but further inland, in the
river valleys (White, Green and Cedar Rivers), yields great-
er than 95 1/s (1,500 gpm) are possible. 105)
In the Seattle region (northwestern King County), ground-
water withdrawals are relatively small. The Seattle water
system obtains its water from the Cedar River. Few indus-
tries use ground water, due in part, to the location of in-
dustrial plants along Elliott Bay and the Duwamish River,
where ground-water supplies are difficult to obtain. Ground
water is used principally for domestic and small municipal
water systems, with an estimated 3,000 domestic wells pump-
ing small quantities of ground water. The principal aqui-
fers in the Seattle region are sand and gravel beds in the
Vashon stratified drift. Yields of wells range from 0.3 to
32 1/s (5 to 500 gpm). 106)
North of Seattle, ground-water development has taken place
in the coastal areas of Skagit and Whatcom Counties. Ground
water accounts for some 30 percent of the total quantity of
irrigation water used. 7)
The islands in Puget Sound are entirely dependent on ground
water because streams are small and intermittent. Wells on
Whidbey and Camano Islands (Island County) supply about 3.8
million cu m (one billion gallons) of water per year. All
ground water is obtained from sand and gravel beds within
glacial and interglacial deposits. Individual water-bearing
zones range in thickness from 3 to 8 m (10 to 25 ft). Well
yields range from 1.2 to 5 1/s (20 to 80 gpm). 107)
Lewis River Province -
The Lewis River province includes the southern portion of
the Puget Trough. "Principal aquifers are the alluvial de-
posits in the Columbia River floodplain and the sand and
gravel beds of Pleistocene and Recent age along the Cowlitz
River and on the lowlands east and north of the city of
Vancouver. These unconsolidated rocks are underlain by
80
-------
Tertiary and older volcanic and sedimentary rocks. Nearly
all public water-supply systems use ground water. Ground-
water use in. 1960 totaled about 4,400 1/s (100 mgd) , 80 per-
cent of which was used by industry. 7) Yields of many in-
dustrial and municipal wells in the Vancouver area are over
125 1/s (2,000 gpm).
Columbia Plateau -
The Columbia Plateau, covering two-fifths of the state, is
divided by mountain ridges and entrenched river channels.
It is underlain by a series of horizontal basaltic lava
rocks consisting of numerous flows with a composite thick-
ness of over 3,000 m (10,000 ft) in the Hanford area. A
relatively thin layer of loess, glacial drift, and other
sedimentary material overlies much of the plateau. The ba-
salt rocks form one of the nation's most important ground-
water reservoirs. Ground water in the basalt is found in
permeable zones such as fractures, shrinkage openings,
joints, and interbedded unconsolidated materials. Water-
bearing zones exhibit marked differences in thickness, per-
meability, and areal extent. In some places, sufficient
volumes of ground water can only be obtained from wells 150
to 300 m (500 to 1,000 ft) deep. Perched and artesian
ground-water conditions prevail in many areas.
In the Yakima River valley and its tributaries, alluvial and
glacial deposits are over 150 m (500 ft) thick. Although
surface water is used for large irrigation projects, ground
water is the source of most public water systems. Infiltra-
tion from streams and irrigation return flow has filled the
aquifers below the valley, and there is a problem of water-
logging in the Kittitas Valley. 96) The mountainous western
portion of the Yakima River basin is underlain by volcanic
rocks of low porosity and permeability, and yields little or
no water to wells.
The Hanford Reservation of the U. S. Atomic Energy Commis-
sion, located along the Columbia River north of Richland, is
underlain by glaciofluvial outwash sands and gravels to a
maximum depth of 52 m (170 ft). Below these deposits is the
Ringold Formation, an extensive lacustrine and fluviatile
deposit of sand, silt, gravel, and clay, with an average
thickness of 90 m (300 ft) but locally reaching 180 m (600
ft). Below these sediments is a series of basalt rocks with
a thickness of at least 3,000 m (10,000 ft). 108) Ground
water occurs under artesian conditions in the basalt rocks
and under water-table conditions in the unconsolidated de-
posits. Ground-water discharge is to the Columbia River.
109)
81
-------
Over 1,300 wells have been constructed on the Hanford proj-
ect area. Some were originally constructed to supply water
for sanitary facilities; others to observe the movement and
quality of ground water in the vicinity of waste disposal
facilities, and still others to obtain geologic data. About
200 to 300 observation and monitoring wells are presently in
use. HO)
East of the Columbia River lies the Columbia Basin Irriga-
tion Project area, covering some 200,000 ha (500,000 acres).
This area has been irrigated with surface water since 1952.
Ground-water levels have risen substantially - as much as 75
m (250 ft) - as a result of irrigation, and available ground-
water reserves have increased greatly. Waterlogging is be-
coming a serious problem in some places. 96) Outside the
Project area, ground water is the chief source of irrigation,
municipal, and domestic supplies.
In the Ritzville-Odessa area, a rapid increase in ground-
water withdrawal for irrigation has resulted in a water-
level decline of 15 to 25 m (50 to 90 ft), prompting the
state's water management agency to close a large part of the
area to further appropriation. HI) Pumpage from 100 irriga-
tion wells in 1965 was some 27 million cu m (22,000 acre-ft).
Well depths range from 60 to 210 m (200 to 700 ft), and
yields of individual wells range from 15 to 125 1/s (a few
hundred to over 2,000 gpm) . H2) In the Walla Walla Basin,
ground water is found in gravel beds located within a thick
clay bed and in the underlying basalt. Pumpage in 1969 was
62 million cu m (50,000 acre-ft), produced equally from the
older gravel aquifer and the basalt. Of this total, about
14 million cu m (11,000 acre-ft) was pumped in the Oregon
part of the basin. 96) Overdraft occurs locally, but the
basin-wide situation shows an annual excess of recharge over
pumpage. 113)
In southeastern Washington (Whitman County), all public sup-
plies are obtained from ground-water sources. Basalt is the
principal aquifer, and the yield of large-diameter wells in
this formation is about 8 to 13 1/s (125 to 200 gpm) for
every 30 m (100 ft) of saturated basalt penetrated. Wells
in the Pullman region, the principal area of ground-water
use, tap an artesian zone in the basalt at about 46 to 52 m
(150 to 170 ft) below the valley floor. Yields of tens of
1/s (several hundred gpm) are also obtained from wells that
penetrate sand and gravel in the Snake River valley. H4)
The average ground-water pumpage in the Pullman area was
about 3 cu hm (800 million gallons) in 1967. Locally, water
levels in some wells have declined 11 m (35 ft) in the 1935-
82
-------
1965 period. 96) Because of concern for falling water lev-
els, applications for additional diversion of artesian
ground water in the Pullman area were curtailed by the Wash-
ington Division of Water Resources in 1953.
Northeast -
This mountainous region includes the Columbia River drainage
basin upstream of the Spokane River, the Okanogan River ba-
sin, Chelan County, a portion of the Pend Oreille River ba-
sin, and the Spokane Valley. The bedrock consists mostly of
intrusive igneous rocks and some sedimentary, metamorphic,
and volcanic rocks. Except for some water-bearing zones in
volcanic rocks, most of the bedrock yields little water to
wells. Principal aquifers are sands and gravels in river
valleys and intermontane basins. In the Spokane Valley,
permeable outwash deposits fill deep buried valleys and con-
stitute a prolific aquifer. Ground water moves through
these outwash deposits toward Spokane from an extensive re-
charge zone (Rathdrum Prairie) across the border in Idaho.
Yields of more than 300 1/s (5,000 gpm) are obtained from
large-diameter wells penetrating these gravel zones. 115)
Recharge to the Spokane Valley aquifer is estimated at more
than 860 million cu m (700,000 acre-ft) per year. Ground-
water pumpage totaled about 185 million cu m (150,000 acre-
ft) in 1973. The city of Spokane, the largest single user
of ground water, obtains its water from ten well fields that
pump about 74 million cu m (60,000 acre-ft) annually. An
additional 33 million cu m (27,000 acre-ft) annually is
pumped for municipal, domestic, and industrial supplies in
the suburban area around the city. 116)
Elsewhere in the region, ground water is used for practi-
cally all domestic and municipal water-supply systems. Ir-
rigation water is obtained from surface sources. Ground-
water development is largest in the valleys of the tribu-
taries of the Columbia River, especially the Okanogan and
Wenatchee.
Wyoming
Wyoming straddles the Continental Divide and contains the
headwaters of four major rivers in the United States. The
Green and Little Snake Rivers in southwestern Wyoming are
the headwaters of the Colorado River, and the Bear River
along the western boundary of Wyoming forms the headwaters
of the Great Salt Lake basin. The Snake River in Jackson
Hole flows westward into Idaho where it joins the Columbia
River. The rivers in the remaining 72 percent of the state
83
-------
form the headwaters of the Missouri River. Important rivers
belonging to the Missouri River drainage system are the Yel-
lowstone, Bighorn, Powder, and North Platte. In south-
central Wyoming, the Continental Divide splits to encircle
a closed drainage basin, the Great Divide Basin.
Precipitation varies from 150 to 200 mm (6 to 8 in) per year
in the desert portions of the Colorado and Missouri River ba-
sins, to over 750 mm (30 in) in the Continental Divide area.
The eastern plains receive about 230 to 400 mm (9 to 16 in)
of precipitation per year. The average annual runoff is
about 75 mm (3 in), equivalent to some 19.5 billion cu m
(15.8 million acre-ft) of water. An additional 1.9 billion
cu m (1.5 million acre-ft) flows into Wyoming from other
states. Wyoming's present consumptive use of surface water
is only about 3.2 billion cu m (2.6 million acre-ft) per year.
About 70 percent of the runoff occurs during spring and early
summer, leaving little water for the rest of the year.
Present users (1973) consume only 15 percent of the state's
surface-water resources. The other 85 percent flows into
other states. Under interstate compacts and court decrees,
Wyoming may have an additional 22 percent of the resource
over the present water allocation. By far the largest con-
sumptive use of water is for irrigation which depletes about
2.65 billion cu m (2.15 million acre-ft) of surface water and
165 million cu m (133,500 acre-ft) of ground water per year
on 690,000 ha (1.7 million acres) of land. Ground water also
supplies 39.6 million cu m (32,100 acre-ft) per year for mu-
nicipal, domestic, and stock use and 62 million cu m (50,400
acre-ft) per year for industrial use. Including irrigation,
the present use of ground water in the state totals some 266
million cu m (216,000 acre-ft) per year, which is equivalent
to 8 percent of all water consumed in the state. H/) Prin-
cipal aquifers in the state are the alluvium, terrace de-
posits, Tertiary sandstones, and Paleozoic limestones.
Significant increases in ground-water use are anticipated in
the Bighorn River basin (irrigation and industry), north-
eastern Wyoming (industry), Platte River basin (irrigation),
Green River basin and Great Divide Basin (industry), and the
Snake River basin (municipal and domestic). Figure 18 shows
the major drainage basins and distribution of the principal
alluvial aquifers. Major consolidated aquifers are shown on
Figure 19. Table 7 lists the various aquifers, ranges in
depth, yields of wells, and total dissolved solids content.
The alluvial aquifers are shallow and thus relatively inex-
pensive to develop. The gross volume of ground water in
storage in the alluvial aquifers is estimated at 12.3 bil-
84
-------
CO
in
NORTHEASTERN
POWDER
MAJOR ALLUVIAL AQUIFERS
25 50 Ml.
Figure 18. Wyoming - Major drainage features and alluvial aquifers. '
-------
NORTH
50
1
I I
25 50 Ml.
Major Tertiary
Sandstone Aquifers
LLLLU Arikaree
Battle Spring
Wasatch
Wind River
I Green River and younger
Tertiary formations
Figure 19. Wyoming - Major Tertiary sandstone aquifers. '
-------
Table 7. WYOMING. WELL DEPTH, YIELD AND WATER QUALITY OF AQUIFERS. 117)
oo
-j
Geologic
period
Quaternary
Tertiary
Note: Ss
Sh
St
Aquifer/ format ion
Sand and gravel
(unconsol i dated)
Ogallala (Ss)
North Park (Ss)
Browns Park (Ss)
Bishop (Cg)
Pass Creek (Cg)
Arikaree (Ss)
White River (St)
Bridge r (Ss)
Green River (Ss)
Wasatch (Ss)
Battle Spring (Ss)
Wind River (Ss)
Fort Union (Ss)
- Sandstone Ls
- Shale Dol
- Siltstone Cg
Drainage basin or area
Green River Basin
Platte River Basin
Northeastern Wyoming
Bighorn River Basin
Snake River Basin
Bear River Basin
Platte River Basin
Green River Basin
Platte River Basin
Green River Basin
Platte River Basin
Green. River Basin
Green River Basin
Platte River Basin
Platte River Basin
Green River Basin
Green River Basin
Green River Basin
Northeastern Wyoming
Bighorn River Basin
Green River Basin
Platte River Basin
Bighorn River Basin
Green River Basin
Northeastern Wyoming
Bighorn River Basin
Depth
wells
3
3
3
3
3
3
46
9
30
range of
in meters
30
90
30
30
30+
56
- 210
30
46
4.6 - 60+
60
11
15
30
9
6
30
12
9
9
23
6
46
46
15
- Limestone
- Dol om i te
- Conglomerate
91 +
37+
43
- 180
- 180
- 300+
- 370+
- 910
- 300
60
- 300
- 170
- 300
- 110
- 180
- 150
Anticipated well
Common range
0.6 -
1.6 -
0.3 -
0.6 -
1.3 -
1.3 -
3
0.3 -
2.5 -
1.
2.
1.
9.5 -
3.2 -
0.3 -
0.06 -
0.6 -
0.06 -
0.06 -
0.06 -
0.06 -
0.06 -
0.06 -
0.06 -
0.06 -
6
19
16
29
16
19
10
6
22
19
6
5
6
50
19
1.6
4.7
6.3
2.5
1.3
6.3
0.9
3.2
6.3
1.9
1.9
yield in l/s
High range
25 - 38
63 - 190
19 - 38
38 - 130
32 - 95+
57 - 130
50 - 1 10
16 - 25
82 (Spring)
63
6.3
13
63 - 69
57 - 130
3.2
13
19-44
6.3 - 38
3.2 - 7.6
19 - 63
6.3 - 19
6.3 - 38
32
6.3
7.6
Total Dissolved Solids
reported range in mg/l
250 -2,800
234 - 786
106 -3,340
256 - 4,600
20 - 600
285 - 1,770
175 - 336
196 - 237
242 - 820
205
176 - 831
558
200 - 380
232 - 468
216 - 713
563 -4,910
500 - 7,000
200 -3,700
160 -6,620
621 - 1,880
200 - 1,000
NA
247 - 5,000
827 -3,320
484 -3,250
1,000
in oil test waters
-------
Table 7 (continued). WYOMING. WELL DEPTH, YIELD AND WATER QUALITY OF AQUIFERS.
oo
00
Geologic
period
Cretaceous
Jurassic
Friassic
Aq u i fe r/ forma t i on
Lance (Ss)
Fox Hills (Ss)
Almond (Ss)
Erickson (Ss)
Rock Springs (Ss)
Mesaverde (Ss)
Cody (Ss)
Frontier (Ss)
Cloverly or Inyan
Kara or Lakota
or Dakota (Ss)
Sundance (Ss)
Nugget (Ss)
Spearfish (Ss)
Chugwater (Ss)
Drainage basin or area
Green River Basin
Platte River Basin
Northeastern Wyoming
Bighorn River Basin
Northeastern Wyoming
Green River Basin
Green River Basin
Green River Basin
Green River Basin
Northeastern Wyoming
Northeastern Wyoming
Bighorn River Basin
Platte River Basin
Northeastern Wyoming
Bighorn River Basin
Green River Basin
Platte River Basin
Northeastern Wyoming
Bighorn River Basin
Green River Basin
Northeastern Wyoming
Green River Basin
Northeastern Wyoming
Platte River Basin
Bighorn River Basin
Depth range of
wel Is in meters
39 - 300+
210i
46 - 370+
15 - 60
60 - 700
30 - 370
18 - 370
27 - 300
880i
12 - 910
30 - 340+
15 - 120
18 - 240
21 - 610
14 - 120
300+
30 -1,070
76 - 1,800
300 -1,500+
l,220t
120 - 210
1,220±
6 - 270+
9-60
12 - 370+
Anticipated well
Common range
0.3 -1.9
0.6
0.06 -3.2
0.06 -0.6
1.3 -4.4
1.3
0.6 -4.7
0.13 -6.3
0.3 -2.5
1 -2.5
0 . 06 -0.3
0.06 -0.3
0.06 -0.3
0.06 -0.3
0.06 -0.3
1.6
0.3 -4.7
1.6 -6.3
1.6 -3.2
0.06 -0.3
0.06 -0.3
3.2
0.06 -2
0.3 -3.8
0.06 - 1
yield in l/s
High range
19
6.3
32
1.9
13 -32
6.3
6.3 - 13
13 -50
6.3
38 - 4.4
6.3 - 13
0.6 - 2
0.6
6.3 - 19
0.6
6.3
7.9 - 16
13 -57
9.5 -22
2
1.6
13
6.3 - 13
13 - 19
6.3 - 13
Total Dissolved Solids
reported range in mg/l
1,600
416- 1,250
450 - 3,060
NA
1,240 - 3,290
500 - 1 , 500
300- 1,500
600 - 6,000
1,170 - 5,300
550 - 1,360; to
34,793*
6', 392 - 12,580
1,750 - 6,240
862 - 3,030
390 - 2,360; to
25,000*
1,800 - 2,350; to
13,071*
223 - 557;
3,000 to 36,000*
278- 1,770
218 - 1,820; to
18,706*
1,905 - 14,825*
1,100 "1 as high as
894 -2,310-50,000 in
9,000 -loil test
water
2,590
1,000 - 2,040
3,040 -43,032*
-------
Table 7 (continued). WYOMING. WELL DEPTH, YIELD AND WATER QUALITY OF AQUIFERS. 117)
Geologic
period
Permian
Pennsyl vanian
Mississippian
oo Devonian
MD
Si lurian
Ordovician
Cambrian
Precambrian
Aqui fer/ formation
Satanka (Ss)
Embar- Phosphor! a
(Ls/Dol)
Tensleep/Amsden
(Ss/Ls), or Casper
(Ss), or Minnelusa
(Ss/ Ls/Dol)
Madison or
Pahasapa (Ls)
Jefferson (Dol)
-
Bighorn (Dol)
Cambrian (Ss)
Granite
Drainage basin or area
Platte River Basin
Bighorn River Basin
Green River Basin
Platte River Basin
Northeastern Wyoming
Bighorn River Basin
Green River Basin
Northeastern Wyoming
Bighorn River Basin
Bighorn River Basin
-
Northeastern Wyoming
Bighorn River Basin
Green River Basin
Northeastern Wyoming
Bighorn River Basin
Platte River Basin
Northeastern Wyoming
Depth range of
we Ms in me te rs
27- 110
76 - 180+
200+
120 - 240
73 - 1 , 980
12 - 910
200±
150 -2,300
270 - 910
1,770+-
-
0 - 60+
610 - 1,220
126+-
20 - 1,800
720 - 1,950
Recharge
areas
Anticipated well yield in l/s
Common range High range
2 38
0.6 9.4 - 44
13
3.2- 11 63
1.6- 16 32 -130
0.6 - 13 32 - 63
13
6.3-160 440-590
3.2 - 47 63 - 160
NA NA
-
63 (spring)
19 -44
6.3 -9.5
13
130 -205
0.6 - 1
0.6 - 1
Total Dissolved Solids
reported range in mg/l
NA
1,078 -44,355*
339 (spring) - 1,650
226 - 274 and 440 (spring)
255 -3,620; to 200,000*
168 -560; 646-5,640*
1,650
290 -3,290
168 -560; 728 -3,902*
3,276*
-
427 -3,219*
166; 408 - 2,895*
214 -663
124; 18,634*
136 -440; 1,869-4,137*
252 (spring)
63 (spring)
-------
lion cu m (10 million acre-ft), and recharge to the aquifers
from precipitation is estimated at 1.2 billion cu m (one
million acre-ft) per year.
The Tertiary sandstones cover extensive areas in the state
and are of interest to the rural population and for stock
supplies. Most wells drilled into sandstones yield small
quantities of water, but large yields are encountered in
some areas. The depths of such sandstone wells commonly
range between 90 and 300 m (300 and 1,000 ft).
Paleozoic sedimentary rocks form excellent artesian.aquifers.
Cavernous limestones and permeable sandstones of Pennsylva-
nian to Cambrian age yield artesian flows of more than 100
1/s (1,600 gpm). Many such wells have been drilled by the
petroleum industry. Sandstones and shales of Cretaceous
through Permian age commonly yield 0.7 to 6 1/s (11 to 100
gpm) to wells. Regional aquifers best suited for large-
scale development are the Arikaree sandstone and the Madison
through Flathead interval.
Since 1954, ground-water studies in the state have been car-
ried out by the U. S. Geological Survey in cooperation with
the Wyoming State Engineer. Ground-water conditions in each
of the major drainage basins is briefly discussed below.
Green River Basin -
Ground water in most of the basin is virtually untapped.
The principal use of ground water is for stock and domestic
purposes. Ground-water pumpage for industrial use (oil well
drilling, secondary recovery processes, coal mining and
trona processing) is some 172 1/s (4 mgd). Some 530 ha
(1,300 acres) are irrigated by ground water. 118)
The shallow, unconsolidated, water-table aquifers are allu-
vial, windblown'and glacial deposits of Quaternary age.
Many of the consolidated Tertiary formations also appear to
have an upper zone of unconfined water that may extend to
depths of over 50 m (several hundred ft) . The Green River,
Wasatch, Fort Union and older formations which underlie most
of the basin contain water under artesian conditions. The
depth to water is generally less than 60 m (200 ft), but the
artesian aquifers in the deeper part of the basin lie at
depths exceeding 300 m (1,000 ft). Well yields range from
0.6 to 6 1/s (10 to 100 gpm). Yields greater than 30 1/s
(500 gpm) could probably be obtained from wells 600 to 1,500
m (2,000 to 5,000 ft) deep, penetrating sandstone aquifers
of the Wasatch and Fort Union Formations and from wells in
the alluvial aquifer near Pinedale and east of Boulder.
90
-------
The eastern part of the basin, including the Great Divide
Basin, is underlain by many sandstone aquifers of different
distribution, thickness, and permeability. Single wide-
spread aquifers with uniform characteristics are not present,
Ground water is generally under artesian pressure. Large
quantities of ground water can probably be obtained from the
Madison Limestone, sandstones of Pennsylvania, Jurassic,
Cretaceous and Tertiary age, and alluvial deposits. 120)
Bear River Basin -
Alluvial sands and gravels in the valley of the Bear River
form the principal aquifer. Well yields range from 6 to 80
1/s (100 to 1,300 gpm).
Snake River Basin -
Ground water is available in floodplain alluvium and valley
fill along the major streams, in glacial outwash deposits,
and in Tertiary bedrock formations. In Jackson Hole, sand
and gravel beds are tapped by wells yielding from 0.6 to 60
1/s (10 to 1,000 gpm). In the Teton Valley, ground water
from alluvium is used for domestic, stock, and irrigation
supplies. In the Salt River valley, alluvial deposits are
over 60 m (200 ft) thick; ground water from this aquifer is
used for irrigation. Total consumptive use of ground water
was about 2.6 million cu m (2,100 acre-ft) in 1970. 121,122)
Yellowstone River Basin -
Almost the entire area lies within Yellowstone National Park.
Ground water obtained from alluvial deposits supplies part
of the domestic and campsite water needs. Small to moderate
yields of 2 to 19 1/s (30 to 300 gpm) and, in some places
(for example, in the valley of Clarks Fork), large yields of
over 60 1/s (1,000 gpm) can be obtained from valley-fill de-
posits that commonly are 30 m (100 ft) thick.
Bighorn River Basin -
The Bighorn River basin includes the Wind River basin and
covers about 50,000 sq km (20,000 sq mi) in north-central
Wyoming. Principal aquifers are the sand and gravel beds on
the floodplains and terraces. Yields from these aquifers
range from 0.6 to 125 1/s (10 to 2,000 gpm). Much of the
recharge to alluvial aquifers and terrace gravels is irriga-
tion return flow. Ground water is also available from Ter-
tiary and older rocks, but because of their considerable
depth below land surface these aquifers have been little de-
veloped. Hundreds of wells tap Tertiary sandstones, such as
91
-------
the Arikaree, Wind River and Fort Union Formations. Well
yields are generally in the range of 0.3 to 7.6 1/s (5 to
120 gpm). Higher yields could be obtained by drilling
deeper into the saturated section.
Cretaceous sandstones, for example the Lance, Mesaverde,
Cody and Frontier Formations, yield 0.3 to 19 1/s (5 to 300
gpm). The Cloverly Formation of Cretaceous age together
with pre-Cretaceous formations, yield water along the flanks
of the mountains. Ground water in these formations is under
confined conditions, and wells flow when first developed.
Yields of 30 1/s (500 gpm) and over are reported from the
Tensleep, Amsden, Madison, Bighorn and Flathead Formations.
Some wells tapping the Madison Limestone yield from 30 to
160 1/s (500 to 2,500 gpm).
The largest user of ground water in the basin, some 62 mil-
lion cu m (50,000 acre-ft) per year, is the petroleum indus-
try. Some 40 million cu m (33,000 acre-ft) of this ground
water is used for waterflooding oil fields by means of in-
jection wells. Pumpage for irrigation was about 27 million
cu m (22,000 acre-ft) in 1970. Domestic and stock use of
ground water consumes some 315 1/s (5,000 acre-ft/yr). In-
dustrial use of ground water is expected to increase sharply
as a result of additional water required by the uranium in-
dustry in the Wind River basin. 123,124)
Northeastern Wyoming -
This semi-arid and very water-deficient area includes the
Powder River basin and the drainage system of the Belle
Fourche and Cheyenne Rivers. As the streams are mostly in-
termittent, ground water is the principal source of water
for drinking, irrigation, stock., and industrial supplies.
Alluvial deposits present in the main river valleys are ca-
pable of yielding moderate to large supplies. However,
most wells tap the Tertiary sandstones which are present
over 70 percent of the area. Yields of wells in sandstone
are generally small, mostly less than 3 1/s (50 gpm), and
the quality of the water is poor. High yields of up to 38
1/s (600 gpm) are possible in some areas from wells drilled
to 300 m (1,000 ft) into Tertiary and Cretaceous aquifers.
Pre-Cretaceous formations, including sandstone and limestone
of the Minnelusa/Tensleep interval and limestone of the
Pahasapa/Madison interval, may yield up to 570 1/s (9,000
gpm) from depths to 3,000 m (10,000 ft). Near the Big Horn
Mountains, industrial wells flow at rates of over 100 1/s
(1,600 gpm) from the Tensleep Sandstone and Madison Lime-
92
-------
stone, encountered at depths of 600 to 2,400 m (2,000 to
8,000 ft). Near the South Dakota state line, the Madison is
known to flow at least 60 1/s (1,000 gpm) from a depth of
300 m (1,000 ft) in municipal water wells. 117,125)
Most stock wells are drilled to about 300 m (1,000 ft) to
encounter artesian aquifers that flow at land surface, thus
eliminating the need for pumping equipment. The uncon-
trolled flow from artesian wells is a significant portion of
the total ground-water diversion in many areas.
Platte River Basin -
The principal aquifers in the Platte River basin are flood-
plain alluvium, valley-fill and terrace gravels, Tertiary
sandstones, and pre-Tertiary sandstone, limestone, and shale.
The unconsolidated aquifers are found along the North Platte
River and its tributaries, along the Niobrara River, Horse
Creek, Lodgepole Creek, and Crow Creek, and within the Lara-
mie basin. Among the major Tertiary aquifers are the Arika-
ree Sandstone in the western and eastern portion of the ba-
sin and the Ogallala Formation in the southeast corner.
Irrigation wells tapping thick alluvial deposits along the
North Platte River in Goshen County yield between 60 to 190
1/s (1,000 to 3,000 gpm). Terrace gravels in the Wheatland
area form excellent aquifers capable of yielding 6 to 30 1/s
(100 to 500 gpm) to wells. In the Carpenter-Egbert-Pine
Bluffs area, similar gravel aquifers yield up to 95 1/s
(1,500 gpm) to wells.
The Ogallala Formation is tapped by municipal wells of the
city of Cheyenne. This aquifer generally yields 3 to 9 1/s
(50 to 150 gpm) to wells, but much larger yields are also
reported. The Arikaree Formation yields moderate to high
supplies of ground water. In the Sweetwater River area,
well yields of 50 to 70 1/s (800 to 1,100 gpm) are reported.
Similar yields are reported from wells tapping the aquifer
in the High Plains region. Locally, the Battle Spring and
the Brule and Chadron Formations of the White River Group
are important aquifers.
Pre-Tertiary formations in the High Plains area, although
highly exploited in Colorado, are little developed here be-
cause ground water is available at shallower depth. In the
Laramie basin, however, these aquifers are present directly
below the floodplain alluvium, and many wells produce water
from these rocks. In other areas, the pre-Tertiary aquifers
have excellent potential, but the great depth is a deterrent
to development.
93
-------
Ground water in the Platte River basin is used extensively
for irrigation, municipal, domestic, stock, and industrial
use. The total consumptive use of ground water in 1970 was
152 million cu m (123,000 acre-ft) per year, equal to 60
percent of all ground water withdrawn in the state. About
90 percent of this ground water was used for irrigation.
About 1,000 irrigation wells supply water to some 28,000 ha
(70,000 acres). Another 28,000 ha (70,000 acres) are irri-
gated partially by ground water. 126)
94
-------
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SECTION IV
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95
-------
11. Bittinger, M. W., "Ground Water in Colorado," Colorado
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96.
-------
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97
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33. Young, H. W., and W. A. Harenberg, "A Reconnaissance of
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98
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99
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54. Watson, I. C., and others, "Feasibility of Desalting
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58. Konizeski, R. L., and others, "Geology and Ground-Water
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100
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65. Lorenz, H. W., and F. A. Swenson, "Geology and Ground-
Water Resources of the Helena Valley, Montana," U. S.
Geological Survey, Circular 83, 1951.
66. Botz, M. K., "Hydrogeology of the Upper Silver Bow
Creek Drainage Area, Montana," Montana Bureau of Mines
and Geology, Bulletin 75, 1969.
67. Groff, S. L., "Reconnaissance Ground-Water and Geolog-
ical Studies, Western Meagher County, Montana," Montana
Bureau of Mines and Geology, Special Publication 35,
1965.
68. Swenson, F. A., "Geology and Ground-Water Resources of
the Missouri River Valley in Northeastern Montana,"
U. S. Geological Survey, Water-Supply Paper 1263, 1955.
69. Zimmerman, E. A., "Geology and Ground-Water Resources
of Northern Elaine County, Montana," Montana Bureau of
Mines and Geology, Bulletin 19, 1960.
70. Zimmerman, E. A., "Preliminary Report on the Geology
and Ground-Water Resources of Parts of Musselshell and
Golden Valley Counties, Montana," Montana Bureau of
Mines and Geology, Information Circular 15, 1956.
71. Torrey, A. E., F. A. Swenson, and H. A. Swenson,
"Ground-Water Resources of the Lower Yellowstone River
Valley Between Miles City and Glendive, Montana," U. S.
Geological Survey, Circular 93, 1951.
72. Moulder, E. A., F. A. Kohout, and E. R. Jochens,
"Ground-Water Factors Affecting Drainage in the First
Division, Buffalo Rapids Irrigation Project, Prairie
and Dawson Counties, Montana," U. S. Geological Survey,
Water-Supply Paper 1424, 1958.
73. Hamilton, L. J., and Q. F. Paulson, "Geology and Ground-
Water Resources of the Lower Bighorn Valley, Montana,"
U. S. Geological Survey, Water-Supply Paper 1876, 1968.
74. Moulder, E. A., and others, "Geology and Ground-Water
Resources of the Lower Little Bighorn River Valley, Big
Horn County, Montana," U. S. Geological Survey, Water-
Supply Paper 1487, 1960.
75. Zimmerman, E. A., "Water Resources of the Cut Bank Area,
Glacier and Toole Counties, Montana," Montana Bureau of
Mines and Geology, Bulletin 60, 1967.
101
-------
76. Willamette Basin Task Force, "The Willamette Basin-Com-
prehensive Study of Water and Related Land Resources,
Appendix B: Hydrology," Pacific Northwest River Basins
Commission, 1969.
77. Frank, J. F., and N. A. Johnson, "Selected Ground-Water
Data in the Eugene-Springfield Area, Southern Willamette
Valley, Oregon," Oregon State Engineer, Ground-Water
Report 14, 1970.
78. Frank, J. F., and N. A. Johnson, "Ground-Water Data in
the Corvallis-Albany Area, Central Willamette Valley,
Oregon," Oregon State Engineer, Ground-Water Report 17,
1972.
79. Hampton, E. R., "Geology and Ground Water of the
Molalla-Salem Slope Area, Northern Willamette Valley,
Oregon," U. S. Geological Survey, Water-Supply Paper
1997, 1972.
80. Price, Don, "Ground Water in the Eola-Amity Hills Area,
Northern Willamette Valley, Oregon," U. S. Geological
Survey, Water-Supply Paper 1847, 1967.
81. Price, Don, "Geology and Water Resources in the French
Prairie Area, Northern Willamette Valley, Oregon," U. S.
Geological Survey, Water-Supply Paper 1833, 1967.
82. Hart, D. H., and R. C. Newcomb, "Geology and Ground Wa-
ter of the Tualatin Valley, Oregon," U. S. Geological
Survey, Water-Supply Paper 1697, 1965.
83. Hogenson, G. M., and B. L. Foxworthy, "Ground Water in
the East Portland Area, Oregon," U. S. Geological Sur-
vey, Water-Supply Paper 1793, 1965.
84. Brown, S. G., "Problems of Utilizing Ground Water in
the West-Side Business District of Portland, Oregon,"
U. S. Geological Survey, Water-Supply Paper 1619-0,
1963.
85. Robison, J. H., "Availability and Quality of Ground Wa-
ter in the Medford Area, Jackson County, Oregon," U. S.
Geological Survey, Hydrologic Investigations Atlas
HA-392, 1971.
86. Robison, J. H., "Availability and Quality of Ground Wa-
ter in the Ashland Quadrangle, Jackson County, Oregon,"
U. S. Geological Survey, Hydrologic Investigations
Atlas HA-421, 1972.
102
-------
87. Hampton, E. R., "Ground Water from Coastal Dune and
Beach Sands," Geological Survey Research 1961, U. S.
Geological Survey, Professional Paper 424-B, 1961.
88. Brown, S. G., and R. C. Newcomb, "Ground-Water Re-
sources of the Coastal Sand-Dune Area North of Coos Bay,
Oregon," U. S. Geological Survey, Water-Supply Paper
1619-D, 1963.
89. Newcomb, R. C., "Quality of the Ground Water in Basalt
of the Columbia River Group, Washington, Oregon and
Idaho," U. S. Geological Survey, Water-Supply Paper
1999-N, 1972.
90. Lystrom, D. J., and others, "Ground Water of Baker Val-
ley, Baker County, Oregon," U. S. Geological Survey,
Hydrologic Investigations Atlas HA-242, 1967.
91. Price, Don, "Ground-Water Reconnaissance in the Burnt
River Valley Area, Oregon," U. S. Geological Survey,
Water-Supply Paper 1839-1, 1967.
92. Hampton, E. R., and S. G. Brown, "Geology and Ground-
Water Resources of the Upper Grande Ronde River Basin,
Union County, Oregon," U. S. Geological Survey, Water-
Supply Paper 1597, 1964.
93. Hogenson, G. M., "Geology and Ground Water of the Uma-
tilla River Basin, Oregon," U. S. Geological Survey,
Water-Supply Paper 1620, 1964.
94. Robison, J. H., "Hydrology of Basalt Aquifers in the
Hermiston-Ordnance Area, Umatilla and Morrow Counties,
Oregon," U. S. Geological Survey, Hydrologic Investiga-
tions Atlas HA-387, 1971.
95. Brown, S. G., and R. C. Newcomb, "Ground-Water Re-
sources of Cow Valley, Malheur County, Oregon," U. S.
Geological Survey, Water-Supply Paper 1619-M, 1962.
96. University of Washington and Washington State Univer-
sity, "An Initial Study of the Water Resources of the
State of Washington," Washington Water Research Center,
Pullman, Wash., 1967.
97. Van Denburgh, A. S., and J. F. Santos, "Ground Water in
Washington - Its Chemical and Physical Quality," Wash-
ington Division of Water Resources, Water Supply Bulle-
tin 24, 1965.
103
-------
98. U. S. Geological Survey, "Water Resources Investiga-
tions in Washington," 1968.
99. Agnew, A. F., and R. W. Busch, "Interstate Ground-
Water Aquifers of the State of Washington," Washing-
ton Water Research Center, Pullman, Wash., Completion
Report A-038-WASH., 1971.
100. Noble, J. B., "A Preliminary Report on the Geology and
Ground-Water-Resources of the Sequim-Dungeness Area,
Clallam County, Washington," Washington Department of
Conservation, Water-Supply Bulletin 11, 1960.
101. Walters, K. L., "Reconnaissance of Sea-Water Intrusion
Along Coastal Washington, 1966-68," Washington Depart-
ment of Ecology, Water-Supply Bulletin 32, 1971.
102. Eddy, P. A., "Preliminary Investigation of the Geology
and Ground-Water Resources of the Lower Chehalis River
Valley and Adjacent Areas, Grays Harbor County, Wash-
ington," Washington Division of Water Resources, Water-
Supply Bulletin 30, 1966.
103. Walters, K. L., and G. E. Kimmel, "Ground-Water Occur-
rence and Stratigraphy of Unconsolidated Deposits,
Central Pierce County, Washington," Washington Depart-
ment of Water Resources, Water-Supply Bulletin 22,
1968.
104. Noble, J. B., and E. F. Wallace, "Geology and Ground-
Water Resources of Thurston County, Washington," Wash-
ington Division of Water Resources, Water-Supply
Bulletin 10, 1966.
105. Luzier, J. E., "Geology and Ground-Water Resources of
Southwestern King County, Washington," Washington De-
partment of ' Water Resources, Water-Supply Bulletin 28,
1969.
106. Liesch, B. A., and others, "Geology and Ground-Water
Resources of Northwestern King County, Washington,"
Washington Division of Water Resources, Water-Supply
Bulletin 20, 1963.
107. Anderson, H. W., Jr., "Ground-Water Resources of Is-
land County, Washington," Washington Department of Wa-
ter Resources, Water-Supply Bulletin 25, Part II, 1968,
104
-------
108. Brown, D. J., "Geology Underlying Hanford Reactor
Areas," General Electric Company, Hanford, Wash.,
Document No. HW-69571, 1962.
109. LaSala, A. M., Jr., and G. C. Doty, "Preliminary Eval-
uation of Hydrologic Factors Related to Radioactive
Waste Storage in Basaltic Rocks at the Hanford Reser-
vation, Washington," U. S. Geological Survey, Open-
file Report, 1971.
110. Essig, T. H., "Radiological Impact of Hanford Waste
Disposal on Ground-Water Quality," Battelle Memorial
Institute, Richland, Wash., BNWL-SA-3744, 1971.
111. Butcher, W. R., and others, "Long-Run Costs and Policy
Implications of Adjusting to a Declining Water Supply
in Eastern Washington," Washington Water Research Cen-
ter, Pullman, Wash., Report 9, 1971.
112. Garrett, A. A., "Ground-Water Withdrawal in the Odessa
Area, Adams, Grant and Lincoln Counties, Washington,"
Washington Department of Water Resources, Water-Supply
Bulletin 31, 1968.
113. Newcomb, R. C., "Geology and Ground-Water Resources of
the Walla Walla River Basin, Washington-Oregon," Wash-
ington Division of Water Resources, Water-Supply Bul-
letin 21, 1965.
114. Walters, K. L., "Reconnaissance of Geology and of
Ground-Water Occurrence in Whitman County, Washington,"
Washington Department of Water Resources, Water-Supply
Bulletin 26, 1969.
115. Cline, D. R., "Ground-Water Resources and Related Geol-
ogy, North-Central Spokane and Southeastern Stevens
Counties of Washington," Washington Department of Wa-
ter Resources, Water-Supply Bulletin 27, 1969.
116. Gillies, N. P., Editor, "The Ground-Water Newsletter,"
Water Information Center, Inc., Port Washington, N. Y.,
Vol. 3, No. 2, Jan. 29, 1974.
117. State Engineer's Office, "The Wyoming Framework Water
Plan," also Summary Report, 1973.
118. State Engineer's Office, "Water and Related Land Re-
sources of the Green River Basin, Wyoming," Wyoming
Water Planning Program Report 3, 1970.
105
-------
119- Welder, G. E., "Ground-Water Reconnaissance of the
Green River Basin, Southwestern Wyoming," U. S. Geo-
logical Survey, Hydrologic Investigations Atlas HA-290,
1968.
120. Welder, G. E., and L. J. McGreevy, "Ground-Water Re-
connaissance of the Great Divide and Washakie Basins
and Some Adjacent Areas, Southwestern Wyoming," U. S.
Geological Survey, Hydrologic Investigations Atlas
HA-219, 1966.
121. State Engineer's Office, "Water and Related Land Re-
sources of the Snake River Basin, Wyoming," Wyoming
Water Planning Program Report 12, 1972.
122. Walker, E. H., "Ground Water in the Upper Star Valley,
Wyoming," U. S. Geological Survey, Water-Supply Paper
1809-C, 1965.
123. State Engineer's Office, "Water and Related Land Re-
sources of the Bighorn River Basin, Wyoming," Wyoming
Water Planning Program Report 11, 1972.
124. Whitcomb, H. A., and M. E. Lowry, "Ground-Water Re-
sources and Geology of the Wind River Basin Area, Cen-
tral Wyoming," U. S. Geological Survey, Hydrologic
Investigations Atlas HA-270, 1968.
125. State Engineer's Office, "Water and Related Land Re-
sources of Northeastern Wyoming," Wyoming Water Plan-
ning Program Report 10, 1972.
126. State Engineer's Office, "Water and Related Land Re-
sources of the Platte River Basin, Wyoming," Wyoming
Water Planning Program Report 9, 1971.
127. Stermitz, Frank, T. F. Hanly, and C. W. Lane, "Water
Resources," in: Mineral and Water Resources of Mon-
tana, Montana Bureau of Mines and Geology, Special
Publication 28, 1963.
128. U. S. Geological Survey, "Water Resources Investiga-
tions in Oregon," 1968.
106
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SECTION V
NATURAL GROUND-WATER QUALITY
INTRODUCTION
The natural quality of ground water varies widely from re-
gion to region, in accordance with geologic and climatic
conditions. The mineral composition of the rocks in the
earth's crust and the length of time water is in contact
with these rocks determines, to a large degree, the quality
of ground water. The combination of volcanism and great
structural deformation in the Northwest is responsible for
the presence of natural ground water of unusually high tem-
peratures, often highly mineralized. Evaporite deposits of
salt and gypsum are present over large areas, often inter-
bedded with other sedimentary rocks. Ground water moving
through these formations readily dissolves minerals and car-
ries them in solution to the eventual discharge point.
In arid zones, where recharge is limited, ground-water move-
ment is very slow. The water is in contact with minerals in
the surrounding rocks longer and becomes more highly miner-
alized. High evapotranspiration rates can cause ground wa-
ter to rise to the land surface and to deposit its mineral
load below or at the land surface. All these factors are
responsible for serious ground-water quality problems in the
Northwest. The states with the most problems are Colorado,
Montana, and Wyoming. Relatively few natural ground-water
problems exist in Idaho and the Pacific Coast states of Ore-
gon and Washington.
PRINCIPAL PROBLEMS OF NATURAL GROUND-WATER QUALITY
Principal problems of ground-water quality in the Northwest
are, in order of importance:
1. Total dissolved solids
2. Iron and manganese
3. Fluoride
4. Trace metals
5. Radionuclides
6. Arsenic
7. Thermal springs
Each of these major ground-water quality problems is dis-
cussed below followed by a description of natural ground-
water quality on a state-by-state basis. Evaluation of the
relative quality of ground water is according to limits for
107
-------
drinking water recommended by the U. S. Public Health Serv-
ice. 1)
Total Dissolved Solids
The U. S. Public Health Service has a recommended limit on
dissolved solids content of 500 mg/1 for potable water.
However, in water-short areas, people may become accustomed
to higher concentrations and use water for drinking that
contains 1,000 mg/1 or more dissolved solids. A concentra-
tion exceeding 2,000 mg/1 makes the water unsuitable for do-
mestic use.
Mapping by the U. S. Geological Survey has indicated that
more than half of the areas of the states of Colorado, Mon-
tana, and Wyoming are underlain by aquifers known to produce
water containing at least 1,000 mg/1 of dissolved solids. 2)
As shown on Figure 20, in most of these regions, the saline
ground water is found at depths shallower than 150 m (500
ft). The concentration of total dissolved solids in the
shallowest ground water is shown on Figure 21. In north-
eastern Colorado and isolated areas of Montana and Wyoming,
concentrations of dissolved solids in shallow ground water
range between 1,000 and 10,000 mg/1. In the Rocky Mountains
in Colorado and on some areas of the Colorado Plateau in
western Colorado, the shallow ground water contains more
than 35,000 mg/1 of dissolved solids. Only a few areas in
Oregon, Washington, and Idaho are underlain by saline ground
water.
In southwestern Colorado, salt anticlines that originated
along faults and formed during the deposition of evaporites,
have salt cores measurable in hundreds of cu km. 3) Col-
lapse and subsequent erosion have exposed these evaporites
to weathering and solution, and the ground water in this re-
gion is typically highly saline. Salt seeps and springs in
western Colorado add over 450,000 metric tons (500,000 tons)
of salt per year to the Colorado River and its tributaries
(see discussion on thermal springs). Similar salt springs
exist in the Green River basin of Wyoming, producing some
9,100 metric tons (10,000 tons) of salt per year. 4) Con-
nate salt water, often under sufficient pressure to flow at
land surface, is present in most areas of the region. The
existence of this mineralized water has become known through
oil and gas exploratory wells and in some cases from deep
water wells. Saline ground water is a frequent by-product
of oil and gas production and is either disposed of at'the
land surface or injected under pressure into the oil or gas
reservoir. Highly saline connate water is also encountered
in most wells drilled through Columbia River basalt flows in
108
-------
NORTH
o
Depth to Saline Ground Water
Meters Feet
H3 Less than 150 500
3 150-300 500-1,000
22 More than 300 1,000
Figure 20. Depth to ground water containing more than 1,000 mg/l dissolved solids. '
-------
NORTH
1-
H
o
K
I V
200
400 KM.
IOO
200 Ml.
4
j
(
y
? s
X
EXPLANATION
Dissolved solids content in mg/l
I , I'less than 1,000
I I 1,000 to 3,000
F5gl 3,000 to 10,000
liiigp Inferred to contain mineralized water
by analogy with other areas where
geologic and hydrologic conditions
are comparable
i »
Figure 21. Quality of shallowest mineralized ground water in the Northwest. 2)
-------
Washington and Oregon. 5, 6,7)
A summary of 149 representative chemical analyses of shallow
saline ground water in the six states is given in Table 8.
A regional variation in chemical composition is noticeable
from individual analyses. In the Rocky Mountains region,
sodium sulfate and sodium chloride waters predominate. So-
dium bicarbonate water is prevalent in eastern Montana. All
ground water containing 20,000 mg/1 or more of dissolved
solids is of the sodium chloride type.
The widespread occurrence of saline and hard ground water
beneath the Great Plains in Montana, Wyoming, and Colorado
is limiting the development of the region and causes a great
amount of economic damage. As shown on Figure 22, the hard-
est ground water occurs in the Plains states. 8) Many towns
tap surface-water supplies for drinking water, but the qual-
ity of surface water, except for the large rivers, is gener-
ally poor, especially in low-flow periods when river dis-
charge is entirely supplied by ground-water discharge. The
ground water is only suitable for stock watering and irriga-
tion of well-drained soils. Many towns in eastern Colorado
and eastern Montana are forced to resort to expensive demin-
eralization to lower the mineral content to acceptable lev-
els for drinking water. Other communities import or haul
water over large distances. Tens of thousands of domestic
households use water treatment devices to lower the mineral
content of water.
In Montana, a review of records of municipal water quality
in 173 communities, practically all supplied by wells, shows
that about half of the communities distribute drinking water
that exceeds U. S. Public Health Service standards for total
dissolved solids and sulfate. Excessive hardness, reaching
1,000 to 1,500 mg/1, is the principal water-quality problem.
9) In Colorado, a study of 91 community water-supply sys-
tems, each serving a population in excess of 500 and almost
all supplied by ground water, indicates that more than
112,000 people in 25 communities receive water with over 500
mg/1 of dissolved solids; 13 communities serving 62,000
people serve water with a dissolved solids content of 1,000
mg/1 or more; 49 municipal systems serve hard water (in ex-
cess of 120 mg/1). High sulfates are a common problem. 10)
Similar problems exist in Wyoming. The median total dis-
solved solids content of shallow ground water in that state
is about 500 mg/1, rising to over 2,000 mg/1 in deeper aqui-
fers. 4) A recent evaluation of the Wyoming public water-
supply program showed that of 76 municipal supplies tested,
45 percent exceeded the U. S. Public Health Service recom-
111
-------
Table 8. TABULATION OF SELECTED CHEMICAL ANALYSES OF SHALLOW SALINE GROUND WATER IN
THE NORTHWEST. 2) Constituents in mg/l (milligrams per liter).
Dissolved Solids
State
— . —
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
(resic
N
17
10
41
11
4
18
ue on evaporation at
R
1,230 -8,900
1,120 -8,095
1,081 -9,207
1,130 -8,450
1,060 - 2,100
1,100 - 6,620
180°C)
M
2,310
1 , 890 a)
l,960a)
3,580
-
2,220
N
36
11
46
16
9
28
Chloride (Cl)
4.0
15
0.5
39
50
7.0
R
- 10,100
- 2,780
- 5,000
- 5,010
- 5,330
- 3,475
M
114
731
72
908
1,050
38
N
34
9
33
17
8
25
Hardness
R
8 -
324 -
4 -
5 -
182 -
3 -
(CaCO3)
v O '
3,910
1,340
1,270
5,400
1,500
3,310
M
634
949
70
800
470
384
N - Number of sample
R - Common range
M - Median
°) ~ Calculated
-------
Table 8 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF SHALLOW SALINE GROUND
WATER IN THE NORTHWEST. 2) Constituents in mg/l (milligrams per liter).
OJ
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
N
36
11
45
17
8
28
N
32
9
27
11
5
22
Alkalinity
R
15-5
168 - 1
20-2
5-2
26 - 1
64 - 1
Nitrate
R
0.0 -
0.0 -
0.0 -
0.0 -
0.0 -
0.0 -
(CaC03)
,580
,970
,480
,550
,880
,430
N03)
29
30
35
17
37
15
M
396
281
533
307
118
352
N
16
6
32
13
5
15
M
2.9
1.5
1.1
0.9
-
0.8
N
28
2
27
10
3
22
Iron (Fe)
R M
0.0 - 3.2 0.10
0.10- 1.5
0.0 - 7.0 0.18
0.0 - 2.9 0.12
0.05 - 9.5
0.03-25 0.72
N
36
11
46
16
6
28
Fluoride (F)
R M
0.4-10 1.4
0.2 - 1.7
0.4 - 5.5 1.7
0.0 - 3.4 0.4
0.1 - 1.4
0.0 - 4.2 0.6
N
34
3
26
12
7
25
Sodium
R
13 -6
40 - 2
2.5 - 3
173 - 3
73 - 4
14 - 2
PH
R
4.0 - 9
6.1 -8
7.2 - 9
6.5 -8
6.6 - 7
6.8 - 9
(Na)
,690
,806
,993
,900
,260
,927
.1
.1
.5
.5
.7
.0
Sulfate (SO4)
M
512
284
486
854
-
460
N R M
37 3.3-5,870 826
11 12 -3,045 153
46 0.0-5,050 486
17 1.1 -5,020 111
6 0.7 - 468
28 52 -4,080 1,000
M
7.5
-
8.0
7.2
7.5
7.6
-------
NORTH
it-
Hardness as CaCC>3 in rhg/l
mm 120-180
180-240
Hover 240
under 60
EZ2260-120
ZOO Ml.
Figure 22. Hardness of ground water in the Northwest. :
8)
-------
mended limits for total dissolved solids and sulfate.
Feasibility studies regarding development of water for in-
dustrial supplies in the northeastern part of that state in-
dicate that none of the ground water available for eventual
use in coal-conversion plants meets the quality required for
boiler-feed water, process water, or cooling water, and de-
mineralization will have to be employed. 12)
The high hardness and high concentration of total dissolved
solids in ground water causes considerable economic damage
to household appliances and plumbing. In Colorado and Wash-
ington, the total household damages caused by treated ground
water supplied by public water systems and water from pri-
vate wells is over ten million dollars per year in each
state (Table 9). In all six states, such damages from min-
eralized ground water are estimated to total some 38 million
dollars per year. Per capita household damage of private
water well systems ranges from a high of $36 per year in
Colorado to less than $6 in Oregon and Washington. Better
quality ground water in Oregon and Washington is reflected
in lower economic damages. 13)
Iron and Manganese
Next to dissolved solids in severity is the occurrence of
iron and manganese in ground waters of the Northwest. The
presence of these constituents is caused by the leaching of
soluble iron and manganese salts from the rocks and sedi-
ments. U. S. Public Health Service limits for iron and man-
ganese in drinking water are 0.3 mg/1 and 0.05 mg/1, respec-
tively. 1) Manganese frequently accompanies iron in ground
water, and the two constituents are generally reported to-
gether. Both are essential for nutrition, and recommended
limits are set entirely for esthetic and taste considera-
tions. Iron and manganese tend to precipitate as hydroxides
and stain laundry and porcelain fixtures. Iron bacteria,
such as Crenothrix, Callionella, utilizing iron as a source
of energy, can colonize in wells and water pipes where iron
concentrations exceed 0.2 mg/1. 14)
The states most plagued by excessive iron and manganese in
drinking water are Washington, Oregon, and Idaho. Lesser
problems occur in the Plains states. Problems of iron and
manganese are tolerated by most users in the absence of bet-
ter quality water. Generally, no obvious relation exists
between type, age, and depth of the aquifer and high iron
concentration. Ground water in the basalt rock of the Co-
lumbia River Group in Washington, Oregon, and Idaho, for ex-
ample, contains only a small amount of iron. 15) in con-
trast, ground water in sedimentary rocks and alluvial de-
115
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Table 9. HOUSEHOLD DAMAGES CAUSED BY USE OF MINERALIZED SURFACE
AND GROUND WATER IN 1970. 13)
State
Total Household Damage, Million $
Public Water Supply
Treated Treated
Surface Water Ground Water
Private Well
Total
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Total:
9.0
0.4
2.3
0.6
3.1
0.9
16.3
2.2
3.3
1.3
1.5
9.3
1.3
18.9
8.0
2.8
2.3
1.7
2.4
1.6
18.8
19.1
6.5
5.9
3.9
14.8
3.9
54.1
State
Per Capita Household Damage, $
Public Water Supply
Treated Treated
Surface Water Ground Water
Private Well
Total
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Average:
5.33
5.71
6.94
0.55
1.64
7.93
4.68
7.24
7.74
8.86
3.29
8.28
9.96
7.56
36.09
12.66
10.83
3.29
5.79
19.76
14.74
8.67
9.08
8.54
1.85
4.33
11.68
7.36
116
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posits frequently contains excessive iron and manganese. In
Snohomish and Whatcom Counties in Washington, excessive iron
in ground water in the unconsolidated aquifer is a regional
problem affecting hundreds of domestic wells. Concentra-
tions of iron up to 1.9 mg/1 and manganese up to 2.9 mg/1
are reported. 16)
Serious iron problems exist in the northern part of the Wil-
lamette Valley in Oregon, in Adams, Bent and Prowers Coun-
ties of Colorado, and in the alluvial aquifers of eastern
Montana. 7,9,10) Iron, manganese, and iron bacteria cause
problems for the Boise, Idaho municipal water-supply system.
Sixteen of 37 public-supply wells produced water exceeding
U. S. Public Health Service limits for iron and/or manganese.
Water mains were found to be corroded and encrusted with
ferric or manganic oxides, and the system yielded "red water"
under certain flow conditions. 17) Management and treatment
of such water quality problems is very costly.
Fluoride
Fluoride is a constituent of fluorite found in sedimentary
rocks and of cryolite in igneous rocks. It is widely pres-
ent in ground water. Fluorides in sufficient quantity are
toxic to humans and may cause fluorosis and bone damage.
Low concentrations of 0.8 to 1.5 mg/1 of fluoride in drink-
ing water aids reduction of dental decay and are considered
beneficial. Higher concentrations, up to 5 mg/1, may cause
mottling of teeth but no harmful effects. 14) u. S. Public
Health Service drinking water standards set a mandatory
limit on fluoride that ranges from 0.8 to 1.7 mg/1 based on
prevailing air temperature. More water is drunk in warmer
climates; thus, the fluoride content should be lower to
prevent excessive total fluoride intake.
The fluoride content of ground water on a county-wide basis
in the Northwest is shown on Figure 23. Maximum (not aver-
age) values are given as of 1962. It is evident that more
high fluoride ground water is present in Montana, Wyoming,
and Colorado than in the other states.
A review of water supplied by 173 municipalities in Montana
shows that 19 water wells belonging to 10 communities pro-
duce water with a fluoride content of 1.5 mg/1 and over.
Maximum concentrations range to 6.4 mg/1. 9) High fluoride
concentrations in ground water occur in northern and north-
eastern Montana, mainly in the Hell Creek and Fort Union
Formations within the Missouri River basin. 19)
In Wyoming, high fluoride in ground water is common in the
117
-------
00
NORTH
0
I-
200
I I
IOO 200 Ml.
1.5 mg/l fluoride or higher reported
in ground water (by County)
Figure 23. Fluoride content of ground water in the Northwest.
18)
-------
Green River basin. Concentrations range from 6.5 to 14 mg/1
in the Wasatch Formation, an artesian aquifer that extends
over 1,500 sq km (600 sq mi) in the northern part of the ba-
sin. 20) in northeastern Wyoming, many regional sedimentary
aquifers are occasionally high in fluoride. 21) The Madison
Formation in the Powder River basin also contains high fluo-
ride concentrations. Analyses of water from 15 wells fin-
ished in the Madison Formation showed a range in fluoride
concentration of 3.2 to 5.0 mg/1. 13)
In Colorado, excessive fluoride content occurs locally in
various aquifers. Of regional impact are high fluoride lev-
els in the deep artesian aquifer in the San Luis Valley. 22)
Figure 24 shows the extent of 2 mg/1 and 5 mg/1 concentra-
tions of fluoride in ground water in this valley. The area
underlain by high fluoride ground water is over 1,000 sq km
(400 sq mi). Values as high as 13 mg/1 have been recorded.
In Idaho, high fluorides are a problem in a majority of wa-
ter wells tapping the basalt aquifer in northern Owyhee
County. 23) Similar problems exist locally elsewhere in the
Snake River basin. 24) The common range of fluoride in the
basalt of the Columbia River Group, which extends over
130,000 sq km (50,000 sq mi) of Idaho, Oregon, and Washing-
ton, is from 0.2 to about 0.8 mg/1. In the synclinal basins
of eastern Oregon and Washington, the basalts contain ground
water with a fluoride content ranging from 0.7 to 2.0 mg/1.
Warm and hot waters of springs and wells contain above aver-
age amounts of fluoride. High fluoride is also reported in
ground water in basalt rock below 300 m (1,000 ft). 15) Be-
low the Columbia Basin Irrigation Project, ground water in
the deeper zones contains fluoride in concentrations above
1.0 mg/1, and the water from some wells exceeds U. S. Public
Health Service limits. 25)
Trace Metals
The geologic rocks and structures in the region, affected by
wide-spread igneous intrusions, contain numerous deposits of
copper, zinc, gold, silver, chromium, and other metals.
Erosion, glaciation, and volcanic emanations have dispersed
many minerals over the land surface. Small quantities are
found in rocks and unconsolidated deposits. Ground water
generally only contains traces of such metallic elements,
and analyses to detect the presence of such constituents are
not routinely undertaken. Most ground-water supplies in
mining regions, such as the Colorado Plateau, are developed
for mining and milling operations; wells in those locations
are drilled into or adjacent to ore bodies and conceivably
could yield quantities of ground water with appreciable min-
119
-------
NORTH
Figure 24. Fluoride concentration of ground water
nrrarion of- ground water in the confine -r
San Luis Valley, Colorado. 22)COnfined °qU'fer'
120
-------
eral content.
Some of the more common trace metals are selenium, cadmium,
and lead. Unfortunately, few problems of excessive concen-
trations of trace elements in ground water are documented.
Selenium is believed to be highly toxic to man, and symptoms
of selenium poisoning are similar to those of arsenic poison-
ing. In trace amounts, however, selenium appears to be an
essential nutritional element. U. S. Public Health Service
drinking water standards call for a mandatory limit of 0.01
mg/1. Excessive selenium (over 0.5 mg/1) in water is poten-
tially dangerous to livestock. 14)
In the Northwest, a regional selenium problem exists in the
Casper, Wyoming area. Selenium in concentrations exceeding
0.01 mg/1 is present in an area of about 1,900 sq km (750 sq
mi). Part of the selenium seems to have originated from
surface-water runoff and irrigation, but high selenium con-
centrations are found locally in ground water from rocks of
Cretaceous age and alluvium. 26) in Colorado, selenium con-
centrations greater than U. S. Public Health Service limits
are present locally in the valley-fill and alluvial aquifers
of the South Platte and Arkansas River valleys. The munici-
pal water wells of Fort Morgan and Las Animas, for example,
yield water with 0.04 mg/1 and 0.023 mg/1 of selenium, re-
spectively. 10)
The presence of molybdenum in water is currently being stud-
ied by the University of Colorado and Colorado State Univer-
sity. 27) Most molybdenum released to the environment ap-
pears to originate in molybdenum mines and uranium and cop-
per mining activities, and there is no information on the
natural molybdenum content of ground water.
Radionuclides
Naturally radioactive substances in ground water are present
in almost all rocks even though the amounts are often below
detection limits. Development of the nuclear industry, nu-
clear weapons testing, and the related increase of radioac-
tivity in the environment from fallout, required that limits
be set on human exposure to radiation.
The Federal Radiation Council has provided criteria in estab-
lishing limits for radioactivity in drinking water. These
limits are based upon three ranges of intake of radioactiv-
ity. For each range, a measure of control action has been
defined as shown below:
121
-------
Ranges of
transient rates
of daily intake Graded Scale of Action
Range I Periodic confirmatory surveillance as
necessary
Range II Quantitative surveillance and routine
control
Range III Evaluation and application of addi-
tional control measures as necessary
Limits have been set for daily intakes of radionuclides with
the provision that dose rates be averaged over a period of
one year. In the case of drinking water, recommended limits
have been established for only two nuclides, namely Radium-
226 (3 picocuries per liter) and Strontium-90 (10 picocuries
per liter). The accumulation of excessive radium and stron-
tium from water constitutes a health hazard. These radionu-
clides ingested into the body are retained and deposited in
the bones, and ultimately may produce bone cancer. Although
a great variety of radionuclides may be present in drinking
water, it has not been considered necessary to establish
limits for those other than Radium-226 and Strontium-90.
Levels of uranium, radium, and tritium in ground water have
been studied by the U. S. Geological Survey. 28,29) Al-
though incomplete so far as sampling coverage, these early
studies showed no excessive amount of radioactivity in
ground water in the Northwest.
Later studies carried out by the Colorado Department of
Health have indicated that excessive radium is present in
the Dakota Sandstone in southeastern Colorado. 30) Hundreds
of wells in Pueblo County tap the aquifer for domestic water
supply and it is common to find wells that yield above 10
picocuries per liter. Of 154 wells sampled in the 1972-73
period, 79 exceeded the 3 picocuries limit; one well meas-
ured 400 picocuries per liter. Broken down according to
Federal radiation guides, the result of the survey was as
follows:
Range Picocuries/day Number of Wells
I 0-2 36
II 2-20 80
III 20 - 200 36
in excess of III 200 2
122
-------
Studies have shown no relation between radium concentration
and well depth. Owners of wells with water exceeding 3 pico-
curies per liter have been advised by local health depart-
ments to discontinue drinking the water. Indications are
that there is excessive Radium-226 in ground water in at
least four other southeastern Colorado counties. Occasion-
ally in the Northwest, analyses of ground water do indicate
some local presence of radium in well water but the Pueblo
County situation is by far the most serious case of radionu-
clides. Many thermal wells and hot springs yield water with
high radium concentrations.
Arsenic
Arsenic is present as native arsenic or arsenopyrite. Arse-
nic oxide is derived as a by-product in the smelting of ar-
senic ores for copper, gold, lead, and silver. Arsenic is
notorious for its toxicity to humans. The U. S. Public
Health Service recommended limit for drinking water is 0.01
mg/1, with a mandatory limit of 0.05 mg/1. However, the
constituent is not normally included in analyses.
A problem of regional significance exists in Lane County,
Oregon, where arsenic in ground water appears to be related
to the Fisher Formation comprised of volcanic deposits. 31)
An area of about 260 sq kin (100 sq mi) is known to be under-
lain by ground water high in arsenic content (Figure 25). A
survey of 174 wells indicated that 53 wells yielded water
with an arsenic concentration higher than 0.01 mg/1. The
largest concentration of arsenic was 1.7 mg/1. It is
thought that the arsenic probably accumulated as volcanic
dust during the deposition of the Fisher Formation and was
later released as a result of chemical alteration.
Isolated cases of arsenic in ground water used for municipal
supplies are reported in Wyoming. Reported concentrations
ranged from 0.01 to 0.02 mg/1. 32)
Thermal Springs
Thermal springs and wells are indicators of possible geo-
thermal resources. Springs and wells are called thermal
when their temperature is at least 8°C (15°F) above the mean
annual air temperature at their locality. There are several
hundred such thermal springs in the Northwest. 33) Their
distribution is shown in Figure 26. Hot springs are common
in extensive areas of lava flows in eastern Oregon, in Idaho,
and Yellowstone National Park in Wyoming. They are also
common in areas where the rocks have been intensely folded
and faulted in geologically recent time (Montana, Colorado).
123
-------
0.02 mg/l to O.I'5 mg/l
More than 0 . 05 mg/l
=i Areas where large concentrations
of arsenic may occur
Figure 25. Arsenic in ground water of Lane County, Oregon. '
124
-------
NORTH
to
en
I T
100 200 Ml.
• THERMAL SPRING
J
oo\
Figure 26. Distribution of thermal springs in the Northwest. '
-------
Because of the high mineral content of ground water, these
thermal springs represent point sources of natural pollution.
In many areas, thermal springs are significant contributors
of salts to surface water drainage features. On the other
hand, the elevated temperature of thermal ground water is
generally considered to be a favorable factor. Thermal wa-
ter from springs and wells is used for heating, bathing> and
irrigation, and in some places, for drinking (bottled water).
In Colorado there are some 200 thermal springs located main-
ly in faulted Paleozoic and Cretaceous rocks of the Rocky
Mountains and associated with igneous rock throughout the
western part of the state. The location of major thermal
springs in western Colorado is shown on Figure 27, and their
characteristics are shown in Table 10. Glenwood Springs is
the largest group of springs, with a total discharge of 240
1/s (4,000 gpm). 34) in Idaho there are numerous hot
springs in the central mountain region. In the Bruneau
River valley, many warm springs rise through overlying lake
sediments or directly from the lava. At least 380 hot
springs and wells are known to occur in central and southern
Idaho. 35) in the city of Boise, 200 houses are heated from
a supply of 53 1/s (1,200,000 gpd) of 77°C (170°F) water. 36)
A summary of chemical analyses of thermal waters from
springs and wells in Idaho is shown in Table 11. The qual-
ity of thermal ground water in Idaho is remarkably good. In
a survey of 124 springs and wells, dissolved solids concen-
trations ranged from 14 to 13,700 mg/1 and averaged 812 mg/1.
However, for the wells and springs in the survey in the
southeastern part of the state, waters were much more min-
eralized with dissolved solids concentrations reaching
13,700 mg/1 and averaging 3,510 mg/1.
In Montana, several warm springs issue from folded and
faulted rocks of Paleozoic age and others from Cretaceous
beds. The largest is Warm Springs, with a temperature of
20°C (68°F) and a discharge of 5,050 1/s (80,000 gpm).
Smaller warm springs are associated with lava beds in val-
leys. Temperatures of the thermal ground water are gener-
ally not high.
In Oregon some 86 thermal springs and wells were inventoried
in 1965, 17 of which flowed in excess of 63 1/s (1,000 gpm).
33) in the southeastern part of the state, warm and hot
springs rise through lake deposits or valley alluvium along
faults in underlying lava. In this region, Columbia River
Group basalt flows are folded and faulted, forming tilted
block mountains and grabens. Principal areas of thermal
spring activity are Klamath Falls, Lakeview, Warner Valley,
Alvord Valley, and the Harney Basin. Small warm springs
126
-------
Thermal spring .
Figure indicates spring number \/f \
as shown on Table 10
h
50
I
100 KM.
I
25
50 Ml.
Figure 27. Location of major thermal springs in western Colorado.
34)
127
-------
Table 10. QUALITY OF THERMAL SPRING WATER IN WESTERN COLORADO. 34)
Map
No. Name of spring
1 Dotsero Springs
2 Glenwood Springs
3 Hot Sulphur Springs
4 Cebolla Hot Springs
!_, 5 Cement Creek Springs
ro
6 Waunita Hot Springs
7 Juniper Hot Springs
8 Orvis Hot Springs
9 Ouray Hot Springs
10 Conundrum Hot Springs
1 1 Penny Hot Springs
(Avalanche Hot Springs)
12 Routt Hot Springs
13 Steamboat Springs
Steamboat Springs
Range in temperature
°C °F
28.5 -31.5 83 - 89
34.5 -65.5 94 - 150
35.5 -45.5 96-114
9.0 -46.0 48-115
24.5 -28.5 76 - 83
62.5 -77.5 145 - 172
35.0-41.0 95-106
52.0-53.8 126-129
33.0 -82.0 91 - 180
38.0 100
44.5-56.5 112-134
64.0-64.5 147-148
39.5-40.0 103-104
15.0 -30.5 59 - 87
l/s
32
250
6
6
22
63
3
2
50
8.2
16
16
126
-
Cumulative
discharge
gpm
500
4,000
100
100
350
1,000
50
35
800
130
250
250
2,000
-
Range of
dissolved solids
mg/l
10,660 - 10,720
17,300 -24,240
742- 1,560
1,600 - 2,600
529 - 689
556 - 559
1,160- 1,690
700 - 2,500
1,000- 1,700
2,310
2,480 - 2,850
458 - 602
884 - 1 , 520
1,900 - 6,180
Principal cation
and anion
Sodium Chloride
Sodium Chloride
Sodium Bicarbonate
Sodium Bicarbonate
Calcium Bicarbonate
Sodium Sulfate
Sodium Bicarbonate
Sodium Sulfate
Calcium Sulfate
Calcium Sulfate
Calcium Sulfate
Sodium Chloride
Sodium Chloride
Sodium Bicarbonate
-------
Table I]
TABULATION OF SELECTED CHEMICAL ANALYSES OF THERMAL GROUND WATER IN COLORADO, IDAHO AND WYOMING.
Concentrations in mg/l (milligrams per liter).
Temperature
3F °C
Dissolved Sol ids
(calculated)
Chloride (Cl)
State
Colorado
Idaho
Wyoming (exclusive of
Yellowstone Park)
State
Colorado
Idaho
Wyoming (exclusive of
Yellowstone Park)
N R M M
13 70-168 150 66
124 54-199 117 47
8 60 - 160 127 53
Hardness (CaCO^)
N R M
13 20 - 1,450 244
124 1 - 3,000 14
8 35 - 1,280 918
N R M
-
124 14 - 13,700 344
-
Alkalinity (CaCOj)
N R M
12 30 - 908 162
123 9 - 2,050 137
8 57 - 814 305
N R M
13 7 - 11,025 103
124 1.1-7,700 14
8 20 - 2,000 324
Iron (Fe)
N R M
-
_
5 0.03 -0.2
N - Number of samples
R - Common range
M - Median
-------
Table 11 (Continued). TABULATION OF SELECTED CHEMICAL AN ALYSES OF THERMAL GROUND WATER I N COLORADO, IDAHO
AND WYOMING. Concentrations in mg/l (milligrams per liter).
Sodium (Na)
State N R M
Colorado 11 17 - 525 162
Idaho 123 3.9-4,300 87
Wyoming (exclusive of
Yellowstone Park) 8 33 - 1,500 266
Fluoride (F)
State N R M
Colorado - - ~
Idaho 124 0.1 -30 6.5
Wyoming (exclusive of
Yellowstone Park) 8 2 - 10 3.5
N R M
13 38 -1,504 199
124 2.2 - 980 33
8 12 -1,430 568
PtL
N R M
121 6.3-9.8 7.8
7 6.2-8.2 7.1
N R M
123 0 - 1.6 0.06
7 0.1 - <10 0.1
U)
o
-------
rise near Mount Hood along the Cascade Mountains and in the
Blue Mountains of northeastern Oregon. In the Klamath Falls
area, about 400 wells varying in depth from 30 to 550 m (100
to 1,800 ft) tap high temperature ground water ranging up to
133°C (235°F). 37)
Thermal spring activity in Washington is rather small.
There are at least 35 mineral and warm springs, but only a
few have been studied. Most are associated with lava flows
in the Cascade Range; other warm springs exist on the Olym-
pic Peninsula.
In Wyoming, some 100 geysers and hot springs, deriving their
heat from magma that underlies thick lava beds, are active
in Yellowstone National Park. In central Wyoming about 30
thermal springs issue from faulted sedimentary rocks. The
Big Horn or Thermopolis Springs are among the largest in the
country. The major spring in the area discharges 800 1/s
(12,600 gpm) and has a temperature of 57°C (135°F). The wa-
ter probably originates in the Tensleep Sandstone. Chemical
analyses of selected thermal springs outside of Yellowstone
Park are listed in Table 11.
As mentioned above, the principal impact of thermal ground-
water discharge on water quality is the quantity of dis-
solved minerals added to surface-water runoff. A case in
point is western Colorado. Fourteen major thermal springs
in the upper drainage basins of the Colorado, Gunnison, Un-
compahgre, and Yampa Rivers discharge more than 57 million
cu m (46,000 acre-ft) per year of saline hot water to the
rivers. The temperature of this water ranges up to 82°C'
(180°F), and the dissolved solids content ranges from 458 to
24,240 mg/1. More than 450,000 metric tons (500,000 tons)
of salt is contributed each year to these rivers by thermal
springs (Table 12). The springs contribute about 30 percent
of the annual dissolved solids load of the Upper Colorado
River above Cameo and about 8.5 percent of the dissolved
solids load of the Yampa River.
BASE-LINE GROUND-WATER QUALITY CONDITIONS
Natural ground-water quality conditions in each of the six
project states are discussed below. The description of
chemical quality of ground water is based on a review of the
literature. Most of the studies on ground-water quality in
the Northwest are less than 20 years old, as comparatively
few ground-water investigations were carried out prior to
1954. Many studies were made specifically to investigate
the feasibility of using ground water for irrigation in rel-
atively small areas, and these data are of limited interest
131
-------
Table T2, DISCHARGE, DISSOLVED SOLIDS LOAD, AND DISSOLVED SOLIDS
CONCENTRATION OF THERMAL SPRINGS IN WESTERN COLORADO.
34)
River Basin
Upper Colorado
above Cameo
Gunnison
Yam pa
Discharge
Cubic meters per day Ac re-feet per year
122,350
17,130
17,130
36,200
5,070
5,070
Total:
156,610
46,340
Dissolved Solids
River Basin
Upper Colorado
above Cameo
Gunnison
Yam pa
Load
Metric tons per year Tons per year
432,000
5,400
31,300
476,000
6,000
34,500
Concentration
mg/l
9,700
870
5,000
Total:
468,700
516,500
132
-------
only-
In recent years, larger regional ground-water investigations
have shed light on both quantity and quality of available
resources. Because of the paucity of historical records,
true base-line data are either not available or of doubtful
nature. Changes in ground-water quality due to man's activ-
ities have taken place, especially in water-table aquifers
subject to impact from irrigation and urbanization. The
quality of water in the deeper sedimentary, volcanic, and
crystalline aquifers probably best approaches base-line
quality standards.
Colorado
Serious ground-water quality problems exist in Colorado.
Large portions of the state are underlain by saline ground
water (Figure 28), and the quality of water in the major
alluvial aquifers is deteriorating. A general description
of ground-water quality in each of the principal ground-
water provinces is given below. Table 13 is a compilation
of chemical analyses of selected constituents in natural
ground waters.
South Platte River Basin -
The average total dissolved solids content of ground water
in the alluvial aquifer in the South Platte River basin near
Denver is about 1,300 mg/1 and increases to about 1,800 mg/1
at the state line. This water is unsuitable for domestic
and municipal supplies, but it is utilized where better
quality water is not available. Although pumped for irriga-
tion, some of the water is of salinity hazard classification.
The water quality of some community well systems that tap
the alluvial aquifer in the South Platte River valley is
shown in Table 14. The actual chemical composition of water
in the valley-fill aquifers varies greatly, even within lo-
cal areas. Generally, the total hardness exceeds 200 mg/1,
and concentrations of total dissolved solids and sulfate ex-
ceed the U. S. Public Health Service recommended upper lim-
its for drinking water (500 mg/1 and 250 mg/1, respectively).
In the main South Platte River valley between the Weld
County line and the town of Gilcrest, total dissolved solids
range from 687 to 1,840 mg/1, sulfate ranges from 182 to 329
mg/1, and chlorides from 76 to 156 mg/1. Further downstream,
from Gilcrest to the state line, total dissolved solids in
the shallow aquifer range from 743 to 4,010 mg/1, sulfate
from 329 to 2,210 mg/1, and chlorides are generally less
than 75 mg/1. 38)
133
-------
I--
LO
50
100 KM.
50 Ml.
Depth to Saline Ground Water
feet meters
less than
500 150
500-1,000 150-300
more than 1,000 300
Figure 28. Cplorado - Depth to ground water containing more than 1,000 mg/l dissolved
solids 2)
-------
Table 13. TABULATION OF SELECTED CH EMICAL ANALYSES OF GROUND WATER I N COLORADO. Concentrations In mg/l
(milligrams per liter). 39 through 44)
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness (CaCO3)
Location - Aquifer
Northern High Plains
Ogallala Formation
South Platte Basin
Al luvium
Pierre Shale
l—i Denver Basin
OJ
Alluvium
Dawson Formation
Laramie Formation
Laramie Formation and Fox Hills
Precambrian Crystalline Rocks
Northern Arkansas Basin
Al luvium
San Luis Valley
Valley fill - unconfined
Valley fill - confined
Piceance Basin
Green River Formation
N - Number of samples
R - Range
N
8
27
6
106
76
5
Sandstone 20
5
42
105
93
17
a) Calculated
b) Sum
205
402
204
141
148
448
371
134
444
72
60
502
R M
304 239
- 8,910°) 1,430
- 2,490°)
- 2,870°) 880
- 2,020°) 238
- 3,680°)
- 1,300°) 596
-50,500°)
- 5,610°) 2,810
-27, 900 b) 263
1 \
- 2,440b) 191
- 6,880b) 805
N
8
27
6
155
109
9
22
8
42
206
130
17
R
2.4 - 9.4
5.2 - 235
3.0 - 560
0 - 1,400
1.0 - 385
6.0 - 3,060
13 - 454
1.0 - 30,200
9.2 - 250
0.3 - 5,220
0.5 - 181
3.0 - 761
M
2.8
32
-
86
6.0
67
64
3.0
78
7.5
1.9
12
N
8
27
6
147
104
7
22
8
42
185
175
17
124
253
14
83
3
6
3
28
288
10
2
27
R
172
- 3,410
949
- 1,800
- 1,240
526
32
- 12,700
- 2,260
- 4,350
360
825
M
142
860
-
416
40
24
9
100
1,460
161
38
106
M - Median
-------
Table 13 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN COLORADO.
(milligrams per liter). 39 through 44)
Concentrations in mg/l
Location - Aquifer
Northern High Plains
Ogallala Formation
South Platte Basin
Al luvium
Pierre Shale
Denver Basin
Alluvium
Dawson Formation
Laramie Formation
Laramie Formation and Fox Hills Sandstone
Precambrian Crystalline Rocks
Northern Arkansas Basin
Al luvium
San Luis Valley
Valley fill - unconfined
Valley fill - confined
Piceance Basin
Green River Formation
N
8
27
6
102
76
7
22
7
42
92
95
17
Alkalinity
131 -
162 -
120 -
35 -
24 -
123 -
285 -
16 -
120 -
21 -
34 -
327 -
(CaC03)
R
182
541
649
1,402
385
558
569
154
376
7,717
2,468
5,176
M
157
280
-
265
164
393
419
105
266
240
146
585
N
8
9
5
64
71
2
20
6
-
_
9
19
Iron (Fe)
R M
0.00 - 0.03 0.00
0.00 - 0.02 0.01
0.00 - 2.40
0.00 - 12.7 0.03
0.00 - 6.0 0.11
0.11 - 4.9
0.00 - 1.6 0.10
0.00 - 31
-
_ _
0.0 - 0.12 0.01
0.009 - 6 0.03
N
8
4
4
111
81
7
19
5
42
131
143
17
Sodium
R
8.6 -
104 -
22 -
10 -
6.2 -
101 -
138 -
7.2 -
21 -
2.5 -
4.8 -
150 -
(Na)
28
228
640
562
1,050
2,040
492
13,700
919
10,400
1,000
2,840
M
16
_
-
Ill
82
294
231
-
338
29
49
270
-------
Table 13 (Continued). TABULATION OF S ELECTED CHEMICAL ANALYS ES OF GROUND WATER I N COLORADO. Concentrations in mg/l
(milligrams per liter). 33)
Fluoride (F)
Location - Aquifer
Northern High Plains
Ogallala Formation
South Platte Basin
Al luvium
Pierre Shale
Denver Basin
Al luvium
Dawson Formation
Laramie Formation
Laramie Formation and Fox Hills Sandstone
Precambrian Crystalline Rocks
Northern Arkansas Basin
Alluvium
San Luis Valley
Valley fill - uncon fined
Valley fill - confined
Piceance Basin
Green River Formation
N
8
27
6
129
99
7
22
5
42
115
99
18
R
9.0 -
54 -
1.2 -
10 -
0.0-
2.5 -
0.6 -
6.2 -
186 -
0.6 -
0.0 -
5.3 -
M
24 12
5, 750 742
1,550
1 , 270 200
1 , 960 20
1 , 960 53
189 4.4
255
3,470 1,710
1 1 , 680 30
60 5.8
798 106
N
129
27
6
97
75
6
17
6
42
182
83
1
2.5
3.9
0.00
0.1
0.0
0.0
0.0
0.2
0.3
0.2
0.0
0.1
R M
- 91 12
-180 28
- 5.6
- 66 16
- 57 0.3
- 8.5
- 3.5 0.1
-222
- 56 18
- 138 4.4
- 17 0.5
-
N
8
4
4
101
76
6
18
7
42
205
186
18
0.8
0.8
0.3
0.1
0
1.0
1.0
0.2
0.6
0.0
0.0
0.4
R
- 1.9
- 2.3
- 3.2
- 8
- 4.4
- 3.6
- 10
- 12
- 8.9
- 20
- 16
-44
M
1.0
-
1.0
1.2
-
2.2
1.0
1.6
0.4
1.6
12
-------
Table 13 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN COLORADO. Concentrations in mg/l
(milligrams per liter). 39 through 44)
Location - Aquifer
Northern High Plains
Ogallala Formation
South Platte Basin
Alluvium
Pierre Shale
Denver Basin
1 •
|— i . .. _.
OJ
00 Alluvium
Dawson Formation
Laramie Formation
Laramie Formation and Fox Hills Sandstone
Precambrian Crystalline Rocks
Northern Arkansas Basin
Alluvium
San Luis Valley
Valley fill - unconfined
Valley fill - confined
Piceance Basin
Green River Formation
N
8
27
6
88
79
2
20
5
42
153
182
16
Silica
24
13
8.3
0
3.2
8.2
8.6
18
12
1.7
15
0.2
(Si02)
R M
- 55 43
- 39 24
-16
- 109 24
-34 11
-11
- 20 14
-83
- 36 18
- 59 35
- 131 54
- 22 12
N
8
27
6
128
96
7
21
7
42
153
186
_
7.5
7.6
7.2
6.5
6.4
7.7
7.6
6.7
7.3
5.1
6.8
pH
R
-7.8
-8.0
-8.3
-8.8
-9.0
-8.9
-8.8
-7.7
-8.1
- 9.6
- 9.5
_
M
7.7
7.8
-
7.5
7.9
8.2
8.1
7.1
7.6
7.7
8.0
-
-------
In the southern tributary valleys of Weld County, the ground
water is highly mineralized. In Boxelder Creek Valley, the
total dissolved solids exceed 1,500 mg/1 and range up to
2,960 mg/1. In the Prospect Valley area of Lost Creek val-
ley, the total dissolved solids commonly exceed 1,000 mg/1
and range up to 4,060 mg/1. In the southern part of the
Prospect Valley area, the ground water is less mineralized,
and its chemical quality is determined largely by recharge
from storm runoff and seepage of South Platte River water
into the aquifer. Good quality ground water occurs in less
developed parts of some southern tributary valleys. For ex-
ample, in lower Beaver Creek valley in Morgan County, the
total dissolved solids of the valley-fill aquifer are only
119 mg/1.
The valley-fill aquifers in the northern tributary valleys
of Lodgepole Creek and upper Crow Creek contain waters with
less than 400 mg/1 of total dissolved solids. In the dense-
ly irrigated areas of lower Crow Creek valley, however, the
total dissolved solids of the shallow ground water generally
exceed 2,000 mg/1. In the valleys of Lone Tree and Spring
Creeks of northwestern Weld County, mineralization increases
in a downstream direction, from about 500 mg/1 of total dis-
solved solids near Nunn to about 2,000 mg/1 in the lower end
of Lone Tree Creek valley.
In the heavily irrigated areas of the lower Cache la Poudre
drainage basin, total dissolved solids in the valley-fill
deposits exceed 2,000 mg/1, and sulfate concentrations com-
monly exceed 1,200 mg/1. These sulfate concentrations are
produced by solution of evaporites (gypsum) present in the
shallow aquifers.
Water quality in the White River Group and Ogallala Forma-
tion of Tertiary age is generally good. Total dissolved
solids in these formations range from 200 to 450 mg/1, and
the total hardness is generally less than 200 mg/1.
The quality of water in underlying Cretaceous bedrock forma-
tions varies greatly. Better quality water occurs at or
near the outcrop and recharge areas, and the quality deteri-
orates with depth and distance from the recharge area. The
hardness of these ground waters is generally lower than that
in the valley-fill aquifer; however, high concentrations of
sulfate are common in water from the Pierre, Fox Hills, and
Laramie formations in northwestern Larimer, north-central
Weld, and northern Morgan Counties.
139
-------
Arkansas River Valley -
Similar to conditions in the South Platte River valley, the
quality of the ground water in the alluvial aquifer general-
ly deteriorates in a downstream direction. For example, the
total dissolved solids, which average 500 mg/1 near Pueblo,
increase to over 4,000 mg/1 at the Kansas state line. The
water is not suitable for drinking, but is used for this
purpose in communities where no better quality water is
available. Among these towns are La Junta, Las Animas, and
Lamar (see Table 14). Poor water quality has slowed the
growth of towns and industrial development in the river ba-
sin. Recently, the Federal Office of Saline Water carried
out studies to examine the technical and economic feasibil-
ity of desalting these municipal water supplies. 10)
In contrast to the generally poor quality water available
from the alluvial-fill aquifer, softer and less mineralized
water can be obtained in some localities from the Cheyenne
Sandstone of the Purgatoire Formation and the Dakota Sand-
stone, both of Cretaceous age. However, locally the ground
water in these sandstones contains excessive hydrogen sul-
fide, iron, fluoride, and radionuclides.
In the southeast corner of the state, rocks of Triassic and
Jurassic age contain some fresh water. These aquifers are
tapped by relatively few wells.
Denver Basin -
The alluvial aquifers in the Denver basin area yield water
of variable quality, controlled by the source of recharge.
In the urban areas, the ground water in the alluvium is
rather mineralized and of poor quality, but outside the city
limits the ground water is of better quality with total dis-
solved solids of 200 to 400 mg/1. Ground water in the bed-
rock aquifers is of fair to good quality. Water from the
upper part of the Dawson Formation frequently contains ex-
cessive iron and radioactive radon gas. The sand, gravel,
and conglomerate of the lower part of the Dawson Formation
yield fairly soft water. Concentrations of dissolved solids
range from 200 to 1,200 mg/1. 42)
The Dawson and Laramie Formations contain carbonaceous de-
bris, coal, and soluble minerals; water from these zones
contains objectionable amounts of dissolved minerals includ-
ing iron, hydrogen sulfide, sodium manganese, silica, chlo-
ride, and calcium carbonate. The Laramie-Fox Hills sand-
stone sequence contains generally good quality water with
total dissolved solids that range from 50 to 800 mg/1. In
140
-------
Table 14. QUALITY OF GROUND WATER OF SOME MUNICIPAL SUPPLY SYSTEMS IN THE SOUTH PLATTE AND ARKANSAS RIVER
VALLEYS, COLORADO - 1971. 10)
South Platte River Basin
Arkansas River Basin
USPHS
Characteristic Standards a'
Total dissolved solids 500 mg/l
Total hardness
Calcium (as CaCO^)
Magnesium
Sodium
Sulfate 250
Iron 0.3
Fluoride 1.4-2.4b)
Selenium 0.01 b)
Nitrate 45
Number of wel Is
Depth
Aquifer
Population
Brighton
1,331
619
438
44
206
435
0.35
1.2
0.002
72
10
11 - 20 m
S. Platte R.
al luvium
8,309
Ft. Lupton
1,221
553
400
41
204
363
0.05
1.4
0.002
45
4
15 - 16 m
S. Platte R.
al luvium
2,489
Ft. Morgan
1,692
920
713
51
158
800
0.05
0.9
0.04
30
8
53 - 77 m
S. Platte R.
alluvium
7,594
La Junta
1,953
962
888
76
198
1,044
0.20
1.3
0.007
10.5
12
12 m
Arkansas R.
al luvium
7,938
Las An i mas
3.075
1,762
1,020
180
480
2,093
3.0
1.6
0.023
2
4
8.5 - 9.4 m
Arkansas R.
al luvium
3,148
Lamar
597
354
380
18
42
337
1.4
0.8
0.006
19.5
15
13 - 28 m
Clay Creek
al luvium
7,797
a) U. S. Public Health Service Drinking Water Standards, 1962. Concentrations in excess of recommended limits are underlined.
b) Cause for rejection, all other values are limits.
-------
areas where local geologic structure impedes ground-water
circulation, the water may contain troublesome amounts of
methane, hydrogen sulfide, iron, and fluoride.
High Plains -
The quality of the water in the Ogallala aquifer is good,
with dissolved solids ranging from 100 to 500 mg/1, and a
hardness ranging from 60 to 400 mg/1. 45) A high silica
content is reported in some areas. Mineralization of water
in the Ogallala in the northern Plains area varies with the
thickness of saturation, the solubility of minerals in the
underlying bedrock, and the presence of dune-sand cover.
Water of better quality is found in the northeastern part of
the area, where dune sand overlies the Ogallala and the sat-
urated section is thick. Water of poorer quality is found
along the western edge of the area and toward the south,
where the saturation is thin. The highest mineralization is
found in the southern part, where the Ogallala is underlain
by Upper Cretaceous calcareous shale of the Niobrara Forma-
tion .
San Luis Valley -
Surface-water diversions from the Rio Grande and other
streams have caused extensive waterlogging in the valley-
fill material. The water table in about half of the San
Luis Basin now lies within 6 feet of the land surface. Evap-
otranspiration losses estimated at some 2.4 billion cu m (2
million acre-ft) per year cause concentration of salts in
the soil, and the shallow ground water has become highly
mineralized. The total dissolved solids in 106 ground-water
samples from the unconfined aquifer ranged from 72 to 29,900
mg/1 with a median value of about 260 mg/1. 43) The least
mineralized water in the shallow aquifer occurs on the west
side of the valley.
The quality of water in the confined aquifer is somewhat
better as far as dissolved solids is concerned. This aqui-
fer is recharged by seepage from mountain streams flowing
across the alluvial fan deposits at the edges of the valley
floor. The concentration of dissolved solids of 93 samples
from this aquifer ranged from 60 to 2,440 mg/1 with a median
value of about 200 mg/1. As discussed previously, the high
fluoride content of the ground water is a problem over a
large portion of the valley.
Western Colorado -
Water in the valley-fill deposits is generally hard and con-
142
-------
tains varying amounts of calcium, magnesium, bicarbonate,
and sulfate. Irrigation water in the Upper Colorado River
basin has a relatively low salt load (300 mg/1), and the
evapotranspiration residue is relatively low. Solution
pickup is high because of the large amount of crystalline
salt in the soil and the shale bedrock. For this reason,
the ground water in the sand and gravel deposits frequently
is more mineralized than the river water, and in some irri-
gated areas the total dissolved solids are above 1,000 mg/1.
Ground-water quality in the bedrock formations is highly
variable. In the Piceance Creek basin, recent studies show
that the quality of ground water in the Green River Forma-
tion varies considerably from place to place. Near the edge
of the basin, the total dissolved solids are less than 2,000
mg/1, but in the center they can be as much as 60,000 mg/1.
Chloride concentrations in the center would be 1,000 mg/1 or
more. 46) Elsewhere in the region, dissolved solids common-
ly are less than 1,000 mg/1 at depths less than 300 m (1,000
ft). Moderately saline or very saline water is common below
600 m (2,000 ft). 38)
The chemical quality of water in the Mesaverde Group is good
to fair for domestic use, with dissolved solids in the range
from 500 to 2,500 mg/1. Fluoride concentrations may exceed
U. S. Public Health Service standards where dissolved solids
concentrations are greater than 750 mg/1. Exploratory wells
indicate that ground water with less than 3,000 mg/1 dis-
solved solids extends to a depth of 1,200 m (4,000 ft). 38)
Water from the Dakota Sandstone east of Meeker generally
contains less than 3,000 mg/1 dissolved solids, ranging be-
tween 500 and 3,000 mg/1. Westward, dissolved solids con-
centrations exceed 3,000 mg/1 in the Dakota Sandstone aqui-
fer.
The chemical quality of the water in the Entrada, Glen Can-
yon, and Wingate Sandstones at shallow depths is good to ex-
cellent for domestic use (less than 500 mg/1 dissolved
solids). The quality of the ground water, however, deterio-
rates rapidly with depth and becomes very saline below 600 m
(2,000 ft).
In the Mississippian limestone aquifer (Leadville Limestone)
fresh water occurs near the outcrop and recharge areas, but
below a depth of 300 m (1,000 ft) it appears to contain
highly mineralized water. Springs discharge essentially
fresh water, but in deep wells, concentrations of several
thousand mg/1 of dissolved solids are encountered, reflect-
ing hydraulic connection with adjacent aquifers carrying wa-
143
-------
ter of a different type.
The quality of ground water in crystalline rocks of the
highland area is good, and the dissolved solids content is
low.
Idaho
The quality of ground water in Idaho is generally good, but
there are local areas where aquifers contain water with high
dissolved solids, sodium, and fluoride. The most prevalent
problem is the presence of hard to very hard water. A com-
pilation of chemical analyses of selected constituents in
natural ground waters is given in Table 15.
Northern and Central Region -
In the Moscow Basin, water from both artesian and unconfined
aquifers is moderately hard and contains excessively large
amounts of iron and silica. Distribution of high concentra-
tions of iron in ground water appears to be related to the
occurrence of iron-rich clays in weathered rock within the
recharge area on the east side of the basin. 54,55)
Ground water in the Salmon River basin is mainly obtained
from valley-fill deposits and is of good quality. In the
Pahsimeroi River basin, a tributary of the Salmon River, the
ground water is moderately hard to hard with total dissolved
solids between 100 and 300 mg/1. Ground water in the sedi-
mentary and crystalline rocks of the upland areas is of good
to excellent quality.
Snake River Basin -
In the Boise-Nampa area, ground water in the shallow aquifer
is generally of good quality and suitable for most purposes.
However, the dissolved solids in many areas exceeds the 250
mg/1 recommended limit for drinking water set by the U. S.
Public Health Service. Locally, the water may be quite hard,
necessitating the use of water softeners. There is no ap-
parent pattern to the distribution of dissolved minerals in
the shallow aquifer. Water-quality information is not avail-
able for the deep aquifer.
In southern Canyon County, ground water from the Idaho For-
mation is generally of good quality, but in irrigated areas,
unconsumed water infiltrating from canals and fields has
caused increases in mineralization and nitrates. 48)
In Ada and Elmore Counties, locally high concentrations of
144
-------
Table 15. TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN IDAHO. Constituents in mg/l (milligrams
per liter). 25, 47 through 53)
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness (CaCO3)
Location and Rock Type
Southeast
Alluvium
Snake Plain Aquifer
NRTS Area
Snake Plain Aquifer
Pahsimeroi River Basin
Alluvium
Southwest
Alluvium
Snake Plain Aquifer
Idaho Formation
Boise -Nampa Area
Shal low aquifers '
N R M
24 286 - 632 364
68 172 -679 a) 334
69 153 - 583 209
7 92 - 345 a) 227
5 103 - 157
8 199 -406 246
6 216-397
5 98 - 667
N R M
24 3-95 26
119 6.5-325 21
69 6.0 - 160 10
7 1.6 - 8.9 6.7
5 1.0- 3.5
8 6.5 - 41 12
5 6-12
64 0-48 5.6
N R
24 8 - 400
36 109 - 440
69 94 - 368
7 67 - 250
5 36-55
8 136-252
5 19-55
5 53 - 306
M
291
226
158
150
161
-
N - Number of samples
R - Range
M - Median
a) Calculated
b) Shallow aquifers include the following hydraulically continuous beds: terrace gravels,
Snake Group basalts, and Quaternary alluvium.
-------
Table 15 Continued. TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN IDAHO. Constituents in mg/l
(milligrams per liter). 25/ 47 through 53)
Location and Rock Type
Southeast
Al luvium
Snake Plain Aquifer
NRTS Area
Snake Plain Aquifer
Pahsimeroi River Basin
Alluvium
Southwest
Alluvium
Snake Plain Aquifer
Idaho Formation
Boise-Nampa Area
Shallow aquifers '
Alkal
N
23
33
69
7
5
8
5
5
inity (as CaCO3) Iron (Fe) Sodium
R M
10-407 256
118-323 192
72-185 139
72 - 260 1 85
60 - 109
125-212 153
1 36 - 274
68-219
N R M
-
67 0.00 -0.52 0.04
7 0 -0.03 0.02
5 0.05-0.60
8 0.02-1.2 0.06
2 0 -0.02
5 0.20-0.76
N R
18 5.0
57 13
69 2.7
7 5.5
2 10
8 6.9
5 59
5 6.6
(Na)
M
-111 22
- 87 22
- 42 8.8
- 64 8.0
-25
- 36 18
- Ill
-65
-------
Table 15 Continued. TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER I N IDAHO. Constituents In mg/l
(milligrams per liter). 25, 47 through 53)
-~J
Location and Rock Type
Southeast
Al luvium
Snake Plain Aquifer
NRTS Area
Snake Plain Aquifer
Pahsimeroi River Basin
Al luvium
Southwest
Alluvium
Snake Plain Aquifer
Idaho Formation
Boise-Nampa Area
Shallow aquifers '
N
24
55
69
7
5
8
5
5
Sulfate
R
0 -
7 -
9.1 -
8.8 -
0.7 -
10 -
0.8 -
2.0 -
(S04)
M
106 32
172 49
57 22
31 17
5.8
55 29
25
148
N
24
80
69
7
2
8
4
128
Nitrate (NOs) Fluoride (F) pH
R M
0.5 - 17 4.0
0 - 16 5.1
0.5 -29 2.0
0.17- 0.79 0.4
0.3 - 4.6
0.3 - 5.1 2.1
0.8-4
0.1 -58 9.4
N R M
22 0 - 1.3 0.3
68 0.2 - 1.0 0.5
69 0 -0.9 0.3
7 0 -0.9 0.2
2 0.3-0.4
8 0.3 - 1.1 0.6
1 7
5 0.3-0.5
N R
24 6.4-7.9
68 7.2-8.5
68 7.2-8.4
7 7.1 -7.7
2 7.2 -7.3
8 7.7-8.2
5 7.8-8.6
37 6.7-7.9
M
7.8
7.8
7.9
7.5
7.9
7.2
-------
total dissolved solids in ground water (600 to 1,200 mg/1)
are found in places along the Snake River, due to irrigation
returns. 56)
In the Bruneau-Grand View area, ground water contains exces-
sive amounts of fluoride and is unsuitable for human consump-
tion. Over 35 wells sampled in Owyhee County do not meet
the U. S. Public Health Service drinking water standard for
fluoride. 23) Average fluoride content of water was 10.6
mg/1. The fluoride is presumed to be derived from silicic
volcanic rocks of the Idaho Formation. The amount of fluo-
ride in basalt is relatively small, and elsewhere in Idaho
ground water derived from basalt contains very little fluo-
ride. 57) The artesian water also contains moderate to high
amounts of sodium and is classified as marginal in quality
for irrigation.
Ground water in the sand and gravel aquifers underlying the
Camas Prairie area is of excellent quality. Total dissolved
solids average about 150 mg/1, and the water is soft.
Ground water in the Big Wood-Silver Creek basin and the Big
Lost River basin is of good quality, moderately hard to hard,
and satisfactory for irrigation.
In the Mud Lake area, most of the ground water is satisfac-
tory for all uses. In certain areas, ground water of poor
quality exists as a result of concentrations of minerals
from irrigation return flow.
In the Twin Falls area, water from the Snake River basalt is
hard and contains large amounts of dissolved solids (400 to
1,300 mg/1); hardness as calcium carbonate averages about
400 mg/1. Marked differences in ground-water quality have
been noted with changes in depth. The total dissolved
solids concentration in the Twin Falls Tract changes from
about 900 mg/1 at a depth of 270 m (900 ft) to 350 mg/1 at
370 m (1,200 ft), while the fluoride concentration increases
from less than one mg/1 to 6.8 mg/1. Water obtained at the
430 to 460 m (1,400 to 1,500 ft) depth was chemically dif-
ferent and of higher temperature. These changes in ground-
water quality are indicative of complex hydrogeological con-
ditions within the basalt aquifer. 58) Most of the ground
water in the Twin Falls area is suitable for irrigation of
selected crop types.
In the Salmon Falls area, serious ground-water quality prob-
lems exist. Ground water is hard to very hard, and is high
in sulfates and total dissolved solids. High nitrates and
boron are reported in some wells. Much ground water pres-
148
-------
ents a medium to high salinity hazard for irrigation and is
not suitable for human consumption. 59)
Ground water in the Raft River basin is very hard and some-
what high in chlorides and sodium. Some of the ground water
has a medium to high salinity hazard. The average dissolved
solids concentration of well and spring water is about 750
mg/1. Observed dissolved solids range from 120 to 3,200
mg/1 within short distances, depending upon depth of wells
and nearness to irrigated areas. 60) Ground water in Power
and western Oneida Counties is generally of fair to poor
quality. 61) The ground water in the Portneuf River basin
is hard and generally contains less than 500 mg/1 in total
dissolved solids. 62)
Snake River Plain -
The chemical and bacteriological quality of ground water in
the Snake Plain aquifer is generally good, and the water is
suitable for most purposes. 52) The pattern of specific con-
ductance values and areas irrigated by ground water are shown
on Figure 29. Wells along the eastern and southern margins
of the Plain generally yield water having a specific conduct-
ance greater than 300 micromhos/cm. The specific conductance
of water in five irrigated areas exceeds 1,000 micromhos per
centimeter. The specific conductance is less than 300 mi-
cromhos/cm in the central part of the Plain.
Chloride concentrations in the Snake Plain aquifer range from
7 to 325 mg/1, although in the heavily irrigated areas most
concentrations range from 10 to 160 mg/1. Nitrate concentra-
tions range from 2 to 32 mg/1, and have an areal distribution
very similar to that of specific conductance and chloride.
The distribution of the various dissolved constituents is
complex, varying laterally and with depth in several areas.
No well-defined seasonal trend in water quality exists.
A substantial amount of water-quality information is avail-
able for the NRTS (National Reactor Testing Station) and the
surrounding area. A water sampling program has been car-
ried out for 20 years using 45 observation wells. The qual-
ity of ground water is exceptionally good due to the abun-
dant recharge from precipitation in the surrounding moun-
tains, the high permeability of the aquifer, and the rapid
underflow of most ground water. Total dissolved solids in
ground water averages about 200 mg/1.
Recent hydrochemical studies have identified several distinc-
tive types of ground water at the NRTS site. 63) Variations
in chemical composition of ground waters beneath the eastern
149
-------
• 5OO— LINE OF EQUAL SPECIFIC CONDUCTANCE,
IN MICROMHOS PER CENTIMETER AT 25°C.
LANDS IRRIGATED BY, OR SUPPLEMENTED BY
GROUND WATER PUMPED FROM WELLS
. APPROXIMATE BOUNDARY OF SNAKE PLAIN AQUIFER
• SPRINGS
Figure 29. Idaho - Conductivity of ground water in the Snake Plain Aquifer.
150
-------
Snake River Plain have made possible the identification of
sources of recharge. Ground water relatively high in cal-
cium, magnesium, and bicarbonate occurs beneath the north-
west half of the NRTS. The composition of this water ap-
proximates the composition of surface water flowing south-
east from the mountainous limestone and dolomite terrane
northwest of the NRTS. Ground water beneath the southeast-
ern half of the NRTS contains lower dissolved solids (175 to
200 mg/1) but greater concentrations of sodium, fluoride,
and silica than ground water in the northwestern half. The
ground water in the southeastern half of the NRTS is traced
to a recharge area west of Yellowstone Park dominated by
rhyolite and thermal water sources.
Little data is available regarding variation of water qual-
ity with depth in the Snake Plain aquifer. However, in one
well drilled to a depth of 366 m (1,200 ft) at the NRTS site,
significant increases were noted in sodium, fluoride, and
silica concentrations with depth, possibly reflecting reac-
tion of ground water with rhyolite=
Grea_t_ B as in -
Ground-water quality in the Curlew Valley in Oneida County
is fair to poor. The conductivity of the ground water
ranges from 1,000 to 4,400 micromhos, and local high concen-
trations of chloride, sulfate, and nitrate occur. Elsewhere,
the ground water in the Bear River basin is suitable for
most purposes, although dissolved solids commonly exceed the
500 mg/1 recommended maximum. This is due, in part, to the
presence of evaporite beds in the lake sediments. 51)
Montana
The quality of ground water is generally excellent to good
in western Montana, excellent to fair in central Montana and
good to poor in the eastern part of the state. Where suffi-
cient recharge is available from precipitation or through
induced infiltration from rivers and streams, the alluvial
and valley-fill deposits yield water of good to excellent
quality. Irrigation practices in many river valleys have
resulted in waterlogging and serious ground-water quality
problems. Poor water quality in some unconsolidated aqui-
fers is due to upward movement of heavily mineralized arte-
sian ground water. There is mounting concern about the
growth of saline-alkali areas in northern Montana.
Ground-water quality in the bedrock aquifers varies greatly.
In central and eastern Montana the water is fairly mineral-
ised because the rocks contain greater amounts of soluble
-------
minerals. It is difficult, if not impossible, to find pota-
ble ground water here within U. S. Public Health Service
recommended limits. Many community water-supply systems
distribute very hard, mineralized water in absence of better
quality water. Studies of the feasibility of desalting such
municipal supplies have been made. 9) The extent and depth
to saline ground water in the state is shown on Figure 30.
The quality of ground water in principal unconsolidated and
bedrock aquifers in various regions is described below.
Table 16 is a compilation of chemical analyses of selected
constituents in natural ground waters.
Unconsolidated Aquifers -
In the Bitterroot Valley, the quality of ground water in un-
consolidated sediments of Recent and Tertiary age is gener-
ally excellent. The hardness of the ground water ranges
from 17 to 210 mg/1, and the total dissolved solids concen-
tration ranges from 40 to 750 mg/1. 81,92) Good quality of
both surface and ground water is a contributing factor to
successful irrigation projects and .steady economic develop-
ment in the valley. Even in waterlogged areas the quality
of the water has not changed appreciably.
In the Kalispell Valley, water from the deep artesian aqui-
fer is moderately hard (average total hardness 180 mg/1) and
has a dissolved solids concentration ranging from 100 to 300
mg/1. It contains excessive amounts of iron and fluoride,
frequently above U. S. Public Health Service standards for
drinking water. 91) Commercial water softeners are used to
alleviate water quality problems. The highly transmissive
gravel aquifer underlying the floodplain is vulnerable to
pollution from floodwaters and man-made causes. Water from
this aquifer generally contains lower iron and dissolved
solids concentrations than water from other aquifers. Hard-
ness varies from ,140 to 200 mg/1, and dissolved solids range
from 130 to 210 mg/1. This variation in quality reflects
the mixing of soft river water with ground water. Iron con-
centrations exceeding 2.0 mg/1 are characteristic of the
water in the sand aquifer. Water from perched dune and
lacustrine aquifers is very hard and high in dissolved
solids.
In the Gallatin Valley, ground water in the alluvial aquifer
is mineralized to about 150 to 400 mg/1 dissolved solids, is
hard, and contains iron in excess of 0.3 mg/1. Water from
underlying Tertiary deposits is more highly mineralized. 87)
In the Townsend Valley, the shallow alluvial aquifer con-
tains hard and mineralized water. The average hardness is
152
-------
CO
f*
I
Depth to Saline Ground Water
feet Meters
2H less than ~500~ 150
-^ 500-1,000 150-300
777 more than 1,000 300
50
I
100 KM.
50 Ml.
Figure 30. Montana - Depth to ground water containing more than 1,000 mg/l dissolved solids.
-------
fable 16 . TABULATI ON OF S ELECTED CH EMICAL ANALYS ES OF GROUND WATER I N MONTANA. Concentrations in mg/l
(milligrams per liter), °4 through 92)
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness
Location - Aquifer
Milk River Basin
Al luvium
Judith River Formation
Marias River Basin
Al luvium
Eagle Sandstone
Missouri River Basin
Alluvium
Fort Union Formation
Hell Creek Formation
Fox Hills Sandstone
Judith River Basin
Al luvium
Eagle Sandstone
Colorado Shale
Kootenai Formation
Madison Group
Upper Yellowstone River Basin
Livingston Formation
N - Number of samples
R - Range
N
7
8
10
14
14
19
13
21
5
12
14
31
7
10
a)
b)
R
2,410 -4,440
1,560 -3,355 °)
377 - 2,630
1,830 -7,360
829 - 2,780
1,120 -5,340
1,000 -5,250
550 -3,920
136 - 826
338 -3,260
194 -2,180
148 - 810
200 -3,359
156 - 736
Sum
Calculated
M
3,180
1,890
1,200
2,700
1,360
2,040
2,790
1,870
1,010
469
389
372
323
N
7
5
10
14
14
19
13
21
5
12
14
31
7
10
51
4.7
8.0
585
5.3
4
4
0
1
2.9
1.1
0.8
3
1
R
- 287
- 221
- 274
-4,350
57
52
32
35
31
43
50
12
26
60
M
115
-
27
1,190
13
21
11
21
8
8
4.5
4
3.5
N
7
7
10
14
11
3
1
-
5
12
14
28
6
10
R
70 -
10 -
24 -
14 -
220 -
42 -
167
-
154-
0 -
0 -
10 -
182 -
120 -
1,010
68
429
201
995
67
583
1,447
337
490
1,370
492
M
297
16
132
48
414
-
-
-
_
190
120
183
-
198
— Median
-------
Table 16 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations i
/ -i i. i.. \ 64 through 92)
(milligrams per liter). a
g/l
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness
01
Location - Aquifer
Lower Yellowstone and Powder River
Basins
Terrace Deposits
Hell Creek and Fort Union Formations
Fox Hills Sandstone and basal part
of Hell Creek Formation
Bighorn River Basin
Al luvium
Terrace Deposits
Marias River Basin
Two Medicine Formation
Eagle Sandstone
Missouri River Basin
Alluvium
Helena Val ley
Al luvium
Townsend Val ley
Alluvium
Tertiary Deposits
N
22
30
18
18
27
13
55
5
15
13
20
408
662
636
400
492
504
350
175
162
180
134
R
- 7,520
-4,900
- 1 , 1 70
- 7,720
- 7,240
"3'440u!
-5,210b)
-8,546
- 514
- 976
- 906
M
1,500
889
788
1,240
1,810
1,440
1,160
-
254
406
362
N R
23 5.5 - 96
30 3.0 - 94
34 2.9 - 43
19 2.0 - 148
32 3.0 - 280
13 9 - 116
52 7 -3,200
5 0-630
15 0.0 - 47
13 3.0 - 136
20 2.5 - 40
M
26
20
20
9.5
18
33
26
-
5.0
16
12
N
20
30
18
28
40
10
39
5
15
13
20
241
0
0
260
291
15
5
20
90
126
84
R
-2,690
- 2,690
33
- 2,650
-2,330
- 775
- 2,450
- 2,264
- 336
- 602
- 517
M
550
11
4
616
599
242
230
-
171
270
272
-------
Table 16 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per liter). 64 trough 92)
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness (CaCO3)
Location - Aquifer N
Gallatin River Valley
Alluvium 20
Terrace Deposits 10
Bitterroot River Valley
Alluvium 1 1
M
Ui Clark Fork River Basin
Ul
Quaternary Deposits 35
Granitic rocks of Boulder
Batholith 4
Flathead River Basin
Alluvium 12
Pleistocene artesian aquifers 27
R M
1 54 - 398 242
162 - 506 300
56 - 278 176
80 - 700 178
158 - 244
132 - 1,480 210
116- 848 214
N R M
22 0.5 - 8.5 2.0
13 1.5- 178 3.5
11 0.8- 8.0 2.8
50 0.1 - 130 4.8
6 2.4 - 6.9
12 2 - 250 4.5
27 1-52 3
N R M
22 114- 312 198
13 17- 305 159
11 25- 183 136
50 22 - 186 74
6 49 - 109
12 135 - 755 200
27 51 - 430 204
-------
Table 16 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per liter). M through 92)
Alkalinity
Iron (Fe)
Sodium (No)
Location - Aquifer
Mi Ik River Basin
Alluvium
Judith River Formation
Marias River Basin
Al luvium
Eagle Sandstone
Missouri River Basin
1 — '
Ln
--J Al luvium
Fotl Union Formation
Hell Creek Formation
Fox Hi Ms Sandstone
Judith River Basin
Al luvium
Eagle Sandstone
Colorado Shale
Kootenai Formation
Madison Group
Upper Yellowstone River Basin
Livingston Formation
N
7
8
10
15
14
19
13
21
5
12
12
31
7
10
R
477 -
599 -
271 -
138 -
288 -
420 -
460 -
315 -
127 -
185 -
178 -
5 -
95 -
115 -
845
1,451
907
959
976
1,719
1,214
1,163
322
633
785
412
235
320
M
750
1,040
394
557
512
726
776
705
320
245
230
160
232
N
7
5
3
3
11
3
1
-
5
12
13
28
4
3
0.4
0.00
0.35
0.10
0.10
0.02
0.68
0
0.00
0.00
0.00
0.0
0.12
R M
- 9.4 5.0
- 2.2
- 7.0.
-1.8
- 4.00 2.10
- 0.05
-
- 1 . 90
- 4.36 0,40
- 4.0 0
-23 0.24
N
5
7
3
10
14
19
13
21
1
2
3
- 0.34 - i
- 0.63
10
685
609
126
725
13
109
331
78
242
7.9
28
6.7
R
-1,250
- 940
- 405
-2,790
- 697
- 1,490
-1,520
- 1,130
25
- 159
-
73
M
656
1,000
248
660
807
547
-
-
-
26
-------
Table 16 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per liter). 64 through 92)
Alkalinity
Iron (Fe)
Sodium (Na)
CO
Location - Aquifer
Lower Yellowstone and Powder River
Basins
Terrace Deposits
Hell Creek and Fort Union Formations
Fox Hills Sandstone and basal part
of Hell Creek Formation
Bighorn River Basin
Al luvium
Terrace Deposits
Marias River Basin
Two Medicine Formation
Eagle Sandstone
Missouri River Basin
Alluvium
Helena Valley
Alluvium
Townsend Valley
Alluvium
Tertiary Deposits
N
24
29
34
28
40
13
53
5
15
13
20
R
218 -
308 - 1
360 - 1
183 -
216 -
280 -
185 -
133 -
71 -
120 -
85 -
640
,599
,169
562
951
869
725
445
254
379
344
M
472
656
616
395
346
581
476
143
222
169
N
20
30
18
12
22
10
43
5
15
13
20
R M
0.06 - 6.9 40
0.00-25.40 0.10
0.00 - 2.10 0.00
0.21 - 3.9 1.55
0.07- 5.5 0.18
0.00 - 18.4 0.52
0.00 - 19.0 0.22
0.0 - 0.7
0.00 - 4.4 0.04
0.02- 1.5 0.10
0.02 - 10 0.18
N R M
24 46 -1,790 314
16 106 - 733 336
21 247 - 877 421
27 18 -1,300 262
38 34 -1,380 194
-
.
15 12 - 34 17
13 8.2 - 61 32
20 6.0 - 84 22
-------
«D
Table 16 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per liter). 64 through 92)
Alkalinity (Ca
Iron (Fe)
Sodium (Na)
Location - Aquifer
Gallatin River Valley
Al luvium
Terrace Deposits
Bitterroot River Valley
Al luvium
Clark Fork River Basin
Quaternary Deposits
Granitic rocks of Boulder
Batholith
Flathead River Basin
Al luvium
Pleistocene artesian aquifers
N R M
22 121 - 274 189
13 92 - 279 202
11 36- 211 140
50 22 - 186 75
6 48 - 108
12 145-574 189
27 110- 698 222
N R M
15 0.02 - 2.6 0.38
7 0.07 - 4.2 1.2
11 0.00 - 4.1 0.16
5 0.02 - 0.15
12 0 - 14.12 0.07
27 0 - 3.8 0.10
N R M
22 2.1 - 20 5.7
13 4.0 - 187 26
7 3.0 - 24 8.6
49 2.6 - 50 10.5
6 6.2 - 15.3
-------
Table 16 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per liter). 64 through 92)
Sulfate (SO4)
Nitrate (NC>3)
Fluoride (F)
Location - Aquifer
Mi Ik River Basin
Alluvium
Judith River Formation
Marias River Basin
Alluvium
Eagle Sandstone
I—1 Missouri River Basin
CTi
o
Al luvium
Fort Union Formation
Hell Creek Formation
Fox Hills Sandstone
Judith River Basin
Al luvium
Eagle Sandstone
Colorado Shale
Kootenai Formation
Madison Group
Upper Yellowstone River Basin
Livingston Formation
N
7
8
10
14
14
19
13
20
5
12
14
31
7
10
978
279
6.2
3.1
58
6.8
157
10
8
55
2.6
2.5
10
8. -5
R
- 2,320
- 1,770
-1,100
72
- 1 , 270
- 2,400
-2,250
- 1 , 730
- 387
- 1 , 958
- 910
- 475
-2,339
- 223
M
1,390
840
281
8.4
516
692
985
556
.
342
116
60
162
38
N
5
5
10
11
11
3
1
-
4
11
11
26
4
10
3.0
0.0
0.0
0.0
0.5
0.0
2.5
0.2
0.0
0.0
0.0
0.0
0.4
R M
- 7.6
- 5.2
- 96 3.0
- 1.5 0.8
- 100 4.0
- 2.5
-
-
-120
-45 1.2
-59 0
-35 0
-62
- 27.0 3.4
N
5
8
10
14
11
3
1
-
4
12
11
25
4
9
R
0.6 -
2.0 -
0.2 -
0.7 -
0.0 -
1.4 -
1.0
-
0
0.2 -
0.24 -
0
0.1 -
0.1 -
1.6
4.5
2.8
3.0
0.8
3.2
0.8
1.1
4.8
2.4
0.5
0.7
M
_
3.2
1.3
1.6
0.5
-
-
-
—
0.6
0.8
0.7
-
0.2
-------
Table 16 (Continued). TABULATION OF S ELECTED CHEMICAL ANALYS ES OF G ROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per liter). 64 through 92)
Sulfate ($04)
Nitrate (NO3)
Fluoride (F)
Location - Aquifer
Lower Yellowstone and Powder River
Basins
Terrace Deposits
Hell Creek and Fort Union Formations
Fox Hills Sandstone and basal part
of Hell Creek Formation
Bighorn River Basin
Al luvium
Terrace Deposits
Marias River Basin
Two Medicine Formation
Eagle Sandstone
Missouri River Basin
Al luvium
Helena Valley
Al luvium
Townsend VaUey
Al luvium
Tertiary Deposits
N
24
30
34
19
32
13
53
5
15
13
20
R
102 -4,860
2.4 - 3,140
15 - 942
28 -4,630
106 -4,400
97 - 1,950
10 -3,090
25 -4,790
12 - 1 46
17 - 204
14 - 308
M
640
62
123
420
808
436
437
-
67
66
86
N R M
24 0.5 - 115 5.6
30 0.0 - 115 0.5
18 0.0 - 0.2 0.0
19 0.0 - 3.8 0.3
31 0.0 - 122 3.3
10 0.0 - 10.6 0.2
34 0.0 - 269 0.9
5 0 - 2.3
15 0.2 - 34 2.7
13 0.2-364 4.4
20 0.4 - 86 4.5
N
24
30
18
18
28
10
37
5
15
9
20
R
0.2 - 1.5
0.0 - 6.0
0.6 - 2.5
0.1 - 0.7
0.1 - 0.8
0.4 - 7.5
0.0 - 3.7
0.2 - 2.4
0.2 - 1.5
0.0 - 1.2
0.0 - 1.2
M
0.6
1.8
1.4
0.3
0.5
1.2
0.8
-
0.4
0.2
0.3
-------
Table 16 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per liter). M through 92)
Sulfate (SO4)
Nitrate (NOs)
Fluoride (F)
M
Location - Aquifer
Gallatin River Valley
Alluvium
Terrace Deposits
Bitterroot River Valley
Al luvium
Clark Fork River Basin
Quaternary Deposits
Granitic rocks of Boulder
Batholith
Flathead River Basin
Al luvium
Pleistocene artesian aquifers
N R M
22 0.0 - 64 20
13 1.0- 116 31
11 1.6 - 24 5.1
50 4 - 269 36
6 22 - 70
12 2 - 200 6.5
27 0-20 5
N R M
22 0.7 - 16 2.8
13 0.4- 24 2.7
10 0.0 - 19 3.2
5 0.0- 1.4
12 0 -208 1.2
27 0 - 5.3 0
N R M
22 0.0 - 0.5 0.1
13 0.0 - 11 0.4
10 0.0 - 0.3 0.2
5 0.0
12 0 0.6 0.1
27 0 4.4 0
-------
Table 16 (Continued). TABULATI ON OF S ELECTED CH EMI CAL AN ALYS ES OF GROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per lifer). 64 through 92)
Location - Aquifer
Milk River Basin
Al luvium
Judith River Formation
Marias River Basin
Al luvium
Eagle Sandstone
1—1 Missouri River Basin
i^\
U)
Al luvium
Fort Union Formation
Hell Creek Formation
Fox Hills Sandstone
Judith River Basin
Al luvium
Eagle Sandstone
Colorado Shale
Kootenai Formation
Madison Group
Upper Yellowstone River Basin
Livingston Formation
N
7
2
3
10
11
3
1
-
1
2
3
6
2
10
Silica (Si 02)
R M
7.5 - 144 19
10
17-23
6.3 - 18 13
11 - 26 16
7.0 - 12
8.0
-
15
3.3 - 23
3.5 - 14.6
0-11
7.2 - 10.2
7.8 - 21 12
N
5
7
10
14
14
18
12
17
_
1
2
2
-
10
pH_
R
7.3 - 7.8
7.6 - 9.0
7.5 - 8.7
8.0 - 9.5
7.1 - 8.4
7.4 -8.7
7.3 -8.4
7.6 - 8.5
_
7.9
7.6 - 8.4
8.2
-
7.5 - 8.0
M
_
8.4
8.2
8.2
7.8
8.1
8.0
8.1
_
-
-
-
-
7.8
-------
Table 16 (ConHnued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations in mg/l
(milligrams per liter). 64 through 92)
h-1
Silica (SiC>2)
Location - Aquifer N R M
Lower Yellowstone and Powder River
Basins
Terrace Deposits 24 9.8 - 31 22
Hell Creek and Fort Union Formations 19 6.3 - 28 12
Fox Hills Sandstone and basal part
of Hell Creek Formation 5 1 1 - 14
Bighorn River Basin
Alluvium 19 10 - 25 17
Terrace Deposits 32 12-30 24
Marias River Basin
Two Medicine Formation -
Eagle Sandstone - -
Missouri River Basin
Alluvium - -
Helena Valley
Alluvium 15 13 - 33 22
Townsend Valley
Alluvium 13 16 - 50 25
Tertiary Deposits 20 9.9 - 38 21
PH
N R M
24 7.2-8.1 7.7
19 7.8-9.0 8.6
21 7.6 - 9.0 8.4
27 7.2-8.3 7.4
36 7.0-8.1 7.5
-
-
15 7.0-8.4 7.5
13 7.2-7.8 7.4
20 7.1 -8.0 7.6
-------
<_n
fable 16 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN MONTANA. Concentrations in mg/1
(milligrams per liter). 64 through 92)
Silica (Si O2)
Location - Aquifer N R M
Gallafin River Valley
Alluvium 22 4.6 - 38 22
Terrace Deposits 13 7.0 - 61 30
Bitterroot River Valley
Alluvium 9 13-36 17
Clark Fork River Basin
Quaternary Deposits 5 4.0 - 9.8
Granitic rocks of Boulder
Batholith - -
Flathead River Basin
Alluvium ~
Pleistocene artesian aquifers -
PH
N R M
22 7.3-8.2 7.6
13 7.5-8.6 7.9
8 6.7-7.7 7.3
50 4.7-8.2 7.1
6 6.8-8.0
-
-------
270 mg/1, and the total dissolved solids are 400 mg/1. The
salinity and hardness of the shallow ground water is greater
in the irrigated areas of the valley. Locally, excessive
concentrations of iron and nitrate occur in the shallow
aquifer. 86)
In the Helena Valley, ground water in the alluvium and in
the Tertiary lake deposits is quite similar in chemical
quality. The total dissolved solids average 250 mg/1, and
the total hardness ranges from 100 to 300 mg/1. Evaporation
of ground water in the waterlogged area has resulted in in-
creased salinity in soil and ground water. 85)
South of the city of Butte, ground water in the alluvial val-
ley fill is generally of good quality. The total dissolved
solids range between 100 and 300 mg/1. Silver Bow Creek,
which drains the area, is severely polluted, and the ground-
water quality near this stream is poorer than in other areas
sampled. 90) This poor quality may reflect ground-water
seepage from mineralized zones. There are some 800 ha
(2,000 acres) of waterlogged land in the valley -
In the White Sulphur Springs area, water from the alluvial
aquifer is hard (180 to 280 mg/1). Some water is high in
dissolved solids (2,000 to 3,000 mg/1) and of limited suita-
bility for irrigation. 72)
In central and eastern Montana, ground water from the uncon-
solidated aquifers is of variable quality. Water in perme-
able glacial deposits such as kames, eskers, and outwash
channels is generally good to excellent. Water in glacial
till in north-central and northeastern Montana is generally
poor. Ground water in the unconsolidated aquifers is. af-
fected by the poor quality water in the surrounding shale
bedrock aquifer. The bedrock contains a large amount of
soluble minerals, and with limited recharge, the slow move-
ment of ground water causes more mineralization to take
place. In the Big Sandy-Laredo area, ground water from
Quaternary deposits is relatively high in total dissolved
solids (400 to 2,600 mg/1) and sulfates (300 to 900 mg/1),
but this water is of better quality than that in the under-
lying bedrock. 19)
In the Milk River valley in Elaine County, the quality of
the water from the alluvial deposits ranges from excellent
to unusable; many wells have been abandoned because of the
alkalinity of their water. 70)
In the Missouri River valley, downstream of the Fort Peck
Reservoir to the North Dakota state line, the water in the
166
-------
alluvial aquifers is of poor quality. It is highly mineral-
ized and hard. The dissolved solids range from 800 to 2,800
mg/1, and the hardness ranges from 200 to 1,000 mg/1. In
addition, the iron content is over one mg/1, and sulfate is
over 250 mg/1. The poor chemical quality of the water ap-
pears to be due to the concentration of constituents by
evaporation and transpiration. 19) Many towns are utilizing
highly mineralized water from municipal supplies in the
absence of better quality water. For example, at Wolf Point,
the municipal water system uses water from the Missouri
River alluvium that is highly mineralized (1,000 to 1,700
mg/1 total dissolved solids) and contains excessive iron (up
to 4.6 mg/1). The underlying bedrock aquifers also contain
highly mineralized water (total dissolved solids 1,000 to
4,400 mg/1). Surface water in the Missouri River is hard,
contains 270 to 460 mg/1 dissolved solids, and receives ir-
rigation return water and untreated industrial waste. 9)
The Flaxville Formation of Tertiary age, underlying some
40,000 ha (100,000 acres) in northern Elaine County, has
relatively good quality water which is suited for irrigation
and drinking. Dissolved solids concentrations range from
350 to 1,500 mg/1 in comparison with concentrations of 1,000
to 4,000 mg/1 for other aquifers in the area. 67)
The alluvium in the Musselshell River valley contains highly
mineralized water in places. In Musselshell and Golden Val-
ley Counties, the water is very hard, containing over 1,000
mg/1 total dissolved solids, and is high in sulfates. 71)
The water quality of the alluvial deposits in the Yellow-
stone River valley appears to deteriorate in a downstream
direction. It varies widely from acceptable to highly min-
eralized. Waterlogging of irrigated land on terraces causes
further deterioration of water quality. 75,76) in the vicin-
ity of Billings, ground water is too highly mineralized to
be used for drinking, but the water appears to be adequate
for livestock. The best ground-water supply in the area con-
tains 300 to 800 mg/1 dissolved solids. Most ground water
contains very high concentrations of sulfate and sodium. 93)
In the lower Bighorn Valley, alluvial gravel deposits are
covered by clay beds that act as confining zones, and ground
water in the alluvium in the irrigated lowlands is under
artesian pressure. Capillary rise and evapotranspiration in
waterlogged areas has produced harmful alkali deposits. Con-
centrations of total dissolved solids in alluvial ground wa-
ter range from 600 to 7,000 mg/1. 79) in the Lower Little
Bighorn River valley, ground water from the unconsolidated
deposits is generally unsuitable for irrigation and domestic
167
-------
use, and in places the dissolved solids exceed 4,000 mg/1.
80)
Bedrock Aquifers -
In western Montana, the quality of ground water in bedrock
aquifers is generally good. The crystalline rocks of the
Belt Series and intrusive rocks are dense and hard and do not
contain readily soluble minerals. In eastern Montana, how-
ever, the sedimentary rocks contain soluble minerals, and the
ground water has become mineralized in many areas. The chem-
ical quality varies greatly from region to region and even
with depth in the same aquifer. For example, water quality
in a given aquifer may be quite acceptable in the outcrop and
recharge area, but away from the recharge area it may deteri-
orate rapidly. Sandstone aquifers that are overlain by shale
containing large amounts of soluble minerals often contain
poorer quality water than sandstone exposed at the land sur-
face. When covered by low permeability shales, such sand-
stones .receive an inadequate volume of recharge to improve
the quality of the water.
In the outcrop area of the Fort Union Formation, most water
wells yield fair to good quality water. In Yellowstone Coun-
ty, the total dissolved solids range from 300 to 1,500 mg/1.
In Roosevelt and Sheridan Counties in northeastern Montana,
the water from depths greater than 30 m (100 ft) is soft, but
moderately to strongly mineralized. Water from lignite beds
is nonpotable. In Valley County, the ground water is low in
dissolved solids concentration but high in sodium content. 94)
Sandstones in the Hell Creek Formation in Yellowstone County
yield water with an average total dissolved solids of 1,000
mg/1. The Hell Creek-Fox Hills aquifer near Terry and on the
western flank of the Cedar Creek anticline yields soft water,
but the water is strong in sodium bicarbonate and not suited
for irrigation. 77,78) The quality of water from the Two
Medicine Formation ranges from good to unusable for domestic
purposes in the Cut Bank area. Water from the Judith River
Formation in northern Hill County and in north-central Mon-
tana is too mineralized for domestic use. In the latter area,
the water contains 1,500 to 3,000 mg/1 dissolved solids, 500
to 1,700 mg/1 sulfate, and 2.0 to 3.5 mg/1 fluoride. 93)
Sandstone of the Eagle Formation supplies good to fair qual-
ity water in the Cut Bank area, in the Judith River basin,
and in Joliet and Carbon Counties. However, in northern Hill
County, a sandstone well 520 m (1,700 ft) deep produces
strongly mineralized water unfit for drinking. On the Fort
Belknap Indian Reservation, water in the Virgelle Sandstone
168
-------
is of fair to poor quality, as the water contains moderate to
large concentrations of sulfate and iron. 6^) Aquifers in
the Kootenai Formation yield good to fair quality water. Ex-
cessive sodium makes the water unsuitable for irrigation in
Big Horn County.
The quality of water from the Madison Limestone is highly
variable. In the Judith River basin and in Cascade County,
water in the upper zone of the aquifer is of good quality;
however, at depth, it is more mineralized. In the Cut Bank
area, the Madison yields water with a dissolved solids con-
tent greater than 7,000 mg/1. In Big Horn County, the Madi-
son Limestone yields low-salinity water from a depth of 1,200
m (4,000 ft) that is suitable for irrigation but not potable
because of its calcium content. In the Bluewater Springs
area of Carbon County, the dissolved solids of Madison water
from a depth of 380 m (1,250 ft) ranges from 1,000 to 1,500
mg/1. 74)
The Amsden, Tensleep, and Chugwater Formations contain aqui-
fers that locally yield good to fair quality water. Water in
the Tensleep Sandstone in Carbon County has dissolved solids
ranging from 1,000 to 2,500 mg/1. 74)
Oregon
The ground water in Oregon is of good to excellent quality.
However, there are local problems of excessive iron, fluoride,
arsenic, and dissolved solids as well as excessive hardness.
Most of the information on ground-water quality is for the
Willamette Valley, where two-thirds of the state's population
is concentrated and ground water is heavily utilized. Less
data are available for the remainder of the state. The qual-
ity of ground water in each region is discussed below- A
compilation of chemical analyses of selected constituents in
natural ground waters is shown in Table 17.
Willamette Valley -
Water in the unconsolidated deposits is of good quality for
most purposes. It is fairly low in dissolved solids (100 to
150 mg/1) and has a hardness of 30 to 150 mg/1. In contrast,
connate ground water from the consolidated sedimentary rocks
below the valley-fill deposits is commonly very hard (greater
than 180 mg/1) and saline. 95) in the southern Willamette
Valley, the sand and gravel aquifer in the Eugene-Springfield
area contains water with dissolved solids of 100 to 200 mg/1
and a hardness of 20 to 130 mg/1. In contrast, the sandstone
aquifer typically yields water with total dissolved solids in
the 500 to 700 mg/1 range and a total hardness of 400 to 600
169
-------
Table 17 . TABULATION DESELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in mg/l
(milligrams per liter). 7< 8' 16< 97 through 112)
Iligrams per liter).
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness
Location - Aquifer
Northern Wil lamette Basin
Alluvium
Columbia River Group basalt
Tualatin Valley
Alluvium
Columbia River Group basalt
M Portland Area
— j
o
Al luvium
Columbia River Group basalt
French Prairie Area
Alluvium
Troutdale Formation
Molalla-Salem Slope Area
Troutdale Formation
N
21
13
9
11
12
6
4
14
6
26
162
100
99
130
126
132
123
61
R M
- 230 134
- 752 212
- 780 278
-3,640 224°)
- 454 154
- 918
- 186
- 276 182
- 195 -b>
N
21
19
10
12
12
9
6
14
6
R M
1.8 - 32 5.5
3.5-11,600 22
2.1 - 350 8.2
1.5- 1,840 22
2-156 6
3.2 - 356 136
0.0 26
2.2 - 23 3.0
2.0 - 6.5
N
21
19
10
12
12
9
6
14
6
9.5
29
36
34
34
14
37
68
22
*j-
R
- 151
- 1,100
- 293
- 1,480
- 163
- 312
- 121
- 146
- 124
M
65
128
84
113
78
107
_
no
-
N - Number of samples
R - Range
M - Median
a) - Total Dissolved Solids
b) - Calculated
-------
M
Table 17 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in mg/l
(milligrams per liter). 7, 8, 16, 97 through 112)
Dissolved Sol ids
residue on evaporation at 180 C)
Chloride (Cl)
Hardness (CaCO3)
Location - Aquifer N R M
Southern Wil larnette Basin
Eugene-Springfield Area
Alluvium 8 24 - 382 155
Corval lis-Albany Area
Alluvium and Terrace Deposits 19 114-1,060 210 b)
Lane County
Fisher Formation and correlative rocks 5 73 - 4,360 - '
Coastal Belt - Coos Bay Area
Sand 3 68 - 162
Rogue River Basin - Medford-
Ashland Area
Alluvium 10 160 - 710 280 a)
Non-marine Sedimentary Rocks 32 165 - 3,400 405
Deschutes River Basin
Alluvium and Fluviolacustrine Deposits 13 136 - 371 254
N R M
5 1.5 - 114
19 2.5 - 590 13
5 1.5 - 2,100
7 10 - 33 18
10 4.2 - 282 13
42 1.5 - 2,020 22
21 2.8 - 20 4.2
N R M
10 20 - 130 46
19 38 - 610 102
5 10 - 1,320
7 16 - 97 18
15 23 - 288 170
50 4 -1,020 190
21 61 - 238 90
-------
Table 17 (Continued). TAB ULATI ON OF S ELECTED CHEMICAL AN ALYS ES OF G ROUND WATER I N OREGON. Concentrations In mg/l
(milligrams per liter 7- 8< 16/ 97 through 112)
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness (CaCO3)
Location - Aquifer N R M
Umatilla River Basin
Columbia River Group basalt 55 114 - 561 253
Grande Ronde River Basin
Alluvium 12 75 - 246 166
Columbia River Group basalt 3 111 - 461
Burnt River Val ley
Alluvium and Fluviolacustrine Deposits -
N R M
73 1.8 - 192 14
12 0.2 10 1.4
7 0.8 - 129 2.1
7 2.8 - 49 12
N R M
72 5 - 334 84
12 20 - 130 92
7 10-28 18
7 6-720 200
-------
Table 17 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in ma/1
(milligrams per liter). 7> 8' 16' 97 through 112)
Alkalinity (CoCOy)
Iron (Fe)
Sodium (No)
Location - Aquifer
Northern Wil lametfe Basin
Al luvium
Columbia River Group basalt
Tualatin Valley
Al luvium
Columbia River Group basalt
Portland Area
I—1
— I Al luvium
Columbia River Group basalt
French Prairie Area
Al luvium
Troutdale Formation
Molal la -Salem Slope Area
Troutdale Formation
N R M
21 4 - 1 58 69
18 11 - 204 127
11 58- 351 151
11 51 - 150 128
10 44- 189 95
9 57-122 95
6 47-130
14 72 - 198 130
6 33-136
N
21
18
7
10
11
8
6
14
6
R M
0.02 - 2.13 0.12
0.02 - 1.2 0.16
0.01 - 0.8 0.1
0.03 - 5.1 0.12
0.01 - 1.8 0.06
0.06 - 0.4 0.14
0.06 - 4.0
0.20 - 5.3 0.94
0.19 - 2.2
N
21
7
4
6
10
3
4
14
6
2.2
8.3
8.9
7.7
4.4
7
3.5
5.6
5.1
R
38
- 2,350
98
- 290
79
10
26
71
25
M
7.0
39
.
-
8.7
-
.
8.8
-
-------
Table 17 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in mg/l
(milligrams per liter). 7' 8' 16' 97 through 112)
Alkalinity (CoCOy)
Iron (Fe)
Sodium (Na)
Location - Aquifer N R M
Southern VVil lame tte Basin
Eugene-Springfield Area
Alluvium 6 60 - 100
Corvallis-Albany Area
Alluvium and Terrace Deposits 16 56 - 266 96
Lane County
Fisher Formation and correlative rocks 5 30 - 259
Coastal Belt - Coos Bay Area
Sand 7 6 - 23 11
Rogue River Basin - Medford-
Ashland Area
Alluvium 15 79 - 303 179
Non-marine Sedimentary Rocks 49 44 - 2,800 225
Deschutes River Basin
Alluvium and Fluviolacustrine Deposits 13 103 - 280 148
N R M
8 0 - 0.65 0.10
19 0.01 - 13.4 0.04
4 0.04 - 0.38
4 0.36 - 2.5
10 0.02 - 19 0.06
33 0.00-13 0.03
20 0.0 - 0.57 0.04
N R M
5 7.4 64
18 5.9- 280 15
5 6.1 - 810
3 8.3- 11.5
10 9.3 - 154 23
42 8.5 - 1,800 62
-------
Table 17 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in mg/l
(milligrams per liter). 7< S' 16' 97 through 112)
Alkalinity (CaCO3)
Iron (Fe)
Sodium (No)
U1
Location - Aquifer N R M
Umatil la River Basin
Columbia River Group basalt 26 53- 212 141
Grande Ronde River Basin
Alluvium 12 29 - 171 88
Columbia River Group basalt 3 59-69
Burnt River Valley
Alluviii-n and Fluviolacustrine Deposits 7 78 - 943 336
N R M
53 0.00 - 16.5 0.07
7 0.00 - 0.27 0.09
5 0.00 - 0.04
N R M
66 6.1 - 133 34
12 2.2 - 28 9.5
7 15-128 27
7 14-397 49
-------
Table 17 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in mg/l
(milligrams per liter). 7, 8, 16, 97 through 112)
Sulfate (SO4)
Nitrate (NO3)
Silica (SiO2)
Location - Aquifer
Northern Wil lamette Basin
Al luvium
Columbia River Group basalt
Tualatin Valley
Al luvium
Columbia River Group basalt
Portland Area
Alluvium
Columbia River Group basalt
French Prairie Area
Alluvium
Troutdale Formation
Molalla-Salem Slope Area
Troutdale Formation
N
21
19
5
10
11
8
6
14
6
2.1
0.6
0
0.6
1.6
0.3
2.5
0.2
0.0
R M
- 10 4.2
- 64 9.8
- 0.8
- 25 2.4
- 20 4.8
- 13 1.2
-13
- 8.0 2.8
- 1.6
N
21
6
2
7
9
3
6
14
6
0.05
0.05
0.1
0.1
0
0.0
0.0
0.0
0.0
R M
- 16 3.6
- 0.5
- 0.3
- 1.5 0.1
- 15 0.4
- 3.5
- 43
-24 0.1
- 0.2
N
21
17
6
10
11
8
6
14
6
8.
30
13
26
40
24
19
20
25
R
8-60
-95
-46
-55
-64
-60
-54
-64
-48
M
41
47
_
44
45
52
_
46
-
-------
Table 17 (Continued). TABULATION OF S ELECTED CHEMICAL ANALYS ES OF GROUND WATER I N OREGON. Concentrations in mg/l
(milligrams per liter). 7, 8, 16, 97 through 112)
Sulfate (SO4)
Nitrate (NC>3)
Silica (SiO2)
^J
Location - Aquifer N R M
Southern Willamette Basin
Eugene-Springfield Area
Alluvium 8 0-21 2.2
Corval lis-Albany Area
Alluvium and Terrace Deposits 18 0-26 6.4
Lane County
Fisher Formation and correlative rocks 5 0.4 - 10
Coastal Belt - Coos Bay Area
Sand 3 0.4 - 3.0
Rogue River Basin - Medford -
Ashland Area
Alluvium 10 1.1-52 6
Non-marine Sedimentary Rocks 41 0.4 -205 17
Deschutes River Basin
Alluvium and Fluviolacustrine Deposits 13 4.0 - 55 15
N R M
6 0.0 - 26
7 0-7.4 1.2
5 0.0 - 9.3
3 0.0 - 1.4
10 0.0 - 41 2.0
41 0.0 - 36 1.4
6 0.1 - 10
N R M
8 9.5 -43 26
17 20-61 42
5 10-40
3 19-23
10 19 -60 34
43 10 -81 24
2 37-51
-------
Table 17 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in mg/l
(milligrams per liter). 7, 8, 16, 97 through 112)
Sulfate (SO4)
Nitrate (NC>3)
Silica (S1O2)
CO
Location - Aquifer N R M
Umatilla River Basin
Columbia River Group basalt 72 0.0 - 120 11
Grande Ronde River Basin
Alluvium 8 0.3 - 23 2.0
Columbia River Group basalt 7 3.3 - 56 4.5
Burnt River Valley
Alluvium and Fluviolacustrine Deposits 7 1.4 - 135 59
N R M
45 0.0 - 57 0.1
12 0.1 - 49 1.1
5 0.0 - 0.2
7 0.0 -205 0.0
N R M
66 20 - 79 57
12 34 -51 42
7 38-88 72
-------
Table 17 (Continued). TABULATION OF S ELECTED CHEMICAL ANALYSES OF GROUND WATER I N OREGON. Concentrations in mg/l
(milligrams per liter). 7, 8, 16, 97 through 112)
Location - Aquifer N R M
Northern Willamette Basin
Alluvium -
Columbia River Group basalt 18 6.2 - 8.3 7.4
Tualatin Valley
Alluvium 7 6.5 - 7.6 7.2
Columbia River Group basalt 11 6.8-8.2 7.4
Portland Area
Alluvium 9 6.5 -8.0 7.4
Columbia River Group basalt 9 6.8-8.6 7.8
French Prairie Area
Alluvium 3 6.6 - 6.8
Troutdale Formation 11 6.7-8.0 7.7
Molalla-Salem Slope Area
Troutdale Formation 6 6.5 - 7.6
-------
Table 17 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in mg/l
(milligrams per liter). 7> 8> 16< 97 through 112)
Location - Aquifer _ N _ R _ M
Southern Wi I lamette Basin
Eugene-Springfield Area
Alluvium 8 6.8 - 8.1 7.4
Corval lis-Albany Area
Alluvium and Terrace Deposits 18 6.3 - 7.8 7.2
Lane County
h-1
oo
o Fisher Formation and correlative rocks 4 7.2 - 8.6
Coastal Belt - Coos Boy Area
Sand 7 5.9-7.8
Rogue River Basin - Medford-
Ashland Area
Alluvium 15 6.8-8.2 7.6
Non-marine Sedimentary Rocks 50 7.1 -9.3 7.8
Deschutes River Basin
Alluvium and Fluviolacustrine Deposits 7 7.1 -8.0 7.6
-------
Table 17 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN OREGON. Concentrations in mg/l
(milligrams per liter). 7' 8' 16' 97 through 112)
Location - Aquifer N R M
Umatilla River Basin
Columbia River Group basalt 72 6.5 - 8.7 8.0
Grande Ronde River Basin
Alluvium 12 6.6-8.0 7.2
Columbia River Group basalt 6 7.4 - 9.5
Burnt River Valley
I — i
co Alluvium and Fluviolacustrine Deposits 7 7.0 - 9.4 7.5
-------
mg/1. 101) Elsewhere in the valley, considerably more saline
ground water (up to 18,500 mg/1 dissolved solids) has been
encountered in the bedrock formations. The occurrence of
high arsenic concentrations in ground water in Lane County
was discussed previously.
In the central and northern part of the valley, the ground wa-
ter is generally of excellent quality and suitable for public
supply and most industrial uses. In the Molalla-Salem Slope
area, iron and manganese concentrations are excessive. Iron
and manganese in water from the Troutdale Formation ranges
from 0.19 to 2.2 mg/1 and averages 0.86 mg/1. Ground water
in the Columbia River Group basalt averaged 0.72 mg/1, and wa-
ter from the marine rocks averaged 1.12 mg/1 of iron. 100,102)
The extent of the area where iron in ground water may exceed
0.35 mg/1 is shown on Figure 31.
In the French Prairie area, a highly productive agricultural
region in the northern Willamette Valley, the quality of
ground water from the nonmarine sedimentary rocks is gener-
ally good. The ground water is low in dissolved solids but
contains excessive iron (over 0.3 mg/1). Silica, derived
from volcanic rock materials through which the water perco-
lates, averages 42 mg/1, making the water undesirable for use
in high-pressure boiler tanks. High sodium and chloride con-
centrations, 147 and 400 mg/1 respectively, in a sample of
ground water from the Columbia River Group suggest that sa-
line water from underlying marine sedimentary rocks may have
percolated into the basalt aquifers of the area. 98)
In the Eola-Amity Hills region, ground water from the Trout-
dale Formation, the alluvial deposits, and the Columbia River
Group is soft to moderately hard and contains low to moderate
concentrations of dissolved solids (85 to 273 mg/1). The ma-
rine sedimentary rocks found beneath the Columbia River Group
contain highly mineralized water below a depth of 60 m (200
ft). 99)
In the Tualatin Valley, the quality of ground water is good.
The average hardness of water from 500 wells tapping all the
known fresh-water aquifers is about 115 mg/1. Deep wells in
the valley fill have an average hardness of 124 mg/1. Saline
ground water originating in rocks older than the Columbia
River basalt is present in some areas. Upward migration of
saline ground water from sedimentary rocks takes place in
areas with unusual geologic structure. 6) Some modes of this
movement of saline water are shown on Figure 32.
In the Portland-Vancouver area, ground water is generally of
good quality. 5,96) Water from the Troutdale Formation and
182
-------
NORTH
10 20
25
« 0.30 mg /I or more
t/ f~\ Areas where iron content
-£-£-4 may exceed 0.35 mg/l
•;;.:-yi Areas where high arsenic
'?»?*w content may be found
Figure 31. Oregon - Iron and arsenic in ground water of the Willamette Basin.
109)
183
-------
BASALT
ZONE BENEATH WHICH COLUMBIA RIVER BASALT MAY CONTAIN
WATER OF EXCESSIVE SALINITY AND HARDNESS
SEDIMENTARY HOCKS
OF TERTIARY A6E
SOURCE OF SALINE WATER
READY FOR EXCLUSION BY
COMPACTION OF THE FORMATION
TENSIONAL OPENING OF
JOINT PLANES
ZONE WHERE WATER IN COLUMBIA RIVER BASALT AND VALLEY
FILL MAY CONTAIN EXCESSIVE SALINITY AND HARDNESS
BASALT
SALINE WATER EXTRUDED BY
COMPACTION OF THE
SHALY STRATA
BASALT
ZONE WHERE PUMPING OF WATER FROM NEAR BASE
COLUMBIA RIVER BASALT MAY EVENTUALLY
CAUSE AN INVASION OF SALINE WATER
PERMEABLE ZONE IN
COLUMBIA RIVER
BASALT(fr*th wot«r)
PERMEABLE ZONE IN'
TERTIARY SEDIMENTARY
ROCKS CONTAINING
SALINE WATER
Figure 32. Oregon - Upward migration of saline ground wafer in the Tualatin Valley.
6)
184
-------
Boring Lava is generally softer and contains less dissolved
solids than water from the Columbia River basalt and the un-
consolidated deposits. The Columbia River basalt yields wa-
ter with dissolved solids of 300 mg/1 and a hardness of 120
mg/1. This water may contain excessive amounts of silica
and iron. Wells drilled through the basalt into Tertiary
marine sedimentary rock yield saline ground water.
The Troutdale Formation supplies moderately hard to hard
ground water in the 60 to 150 mg/1 range. Water from the
Boring Lava is quite similar in chemical properties to water
from the Troutdale Formation. Ground water in the alluvium,
terrace sands and gravels, and other unconsolidated deposits
is of good quality with dissolved solids of 110 to 500 mg/1
and an average hardness of 110 mg/1. Local excessive concen-
trations of iron and silica occur in all aquifers. Upward
migration of saline water as a result of pumping and subse-
quent lowering of artesian pressure in the basalt aquifer is
taking place within the city of Portland. 97)
Medford and Ashland Areas -
Ground water in alluvial aquifers in the Medford and Ashland
areas is usually hard. Nonmarine sedimentary rocks yield
mostly calcium bicarbonate water. Near Medford, high fluo-
ride, boron, and iron are encountered in some wells. 103,104)
Highly concentrated sodium bicarbonate chloride water, lo-
cally known as Lithia water, is found in the nonmarine sedi-
mentary rocks near Ashland. This ground water is bottled
and converted into dry ice.
Coastal Belt -
Ground water in the coastal dune and beach sands is of good
chemical quality. It is soft and contains only about 20 mg/1
chloride. Some of the water contains excessive dissolved
iron, and some may be sufficiently acid to require treatment
for some uses. 110,111)
Eastern Oregon -
The ground water within the layered basalt of the Columbia
River Group is of good quality. It is a generally uniform
bicarbonate water having calcium and sodium in nearly equal
concentrations as the principal cations. The water contains
a relatively large amount of silica. Minor constituents,
such as heavy metals and alkali metals, are present in small
amounts, and the natural radioactivity of the ground water is
low. Locally, the water contains some iron. Hydrogen sul-
fide gas is present in water from most wells, a common condi-
185
-------
tion for water from the basalt of the Pacific Northwest. 15)
Apparently the gas is released by decomposition of iron sul-
fides in the lava rock. Total dissolved solids in the ground
water commonly range from 150 to 400 mg/1, and the hardness
ranges from 50 to 250 mg/1. Some sodium-fluoride ground wa-
ter is found in north-central Oregon (The Dalles-Umatilla
syncline).
The quality of ground water from sedimentary deposits over-
lying the basalt varies. In the Umatilla River basin, the
hardness ranges from 40 mg/1 in the alluvium to 100 mg/1 in
glaciofluviatile deposits. 106) The average hardness of wa-
ter from the alluvium in the Grande Ronde River basin is 90
mg/1. 108) Higher hardness (200 mg/1) and dissolved solids
(400 mg/1) are reported from the alluvial deposits in the
Deschutes River basin. 10->)
Washington
The quality of ground water in Washington is generally good
to excellent. In the humid part of the state, high precipi-
tation and recharge to the aquifers tend to dilute the ground
water in situ. Evaporation losses are low, and highly solu-
ble or moderately soluble minerals are absent. East of the
Cascades, most ground water is of good quality, but there are
local problems of excessive dissolved solids. Large concen-
trations of iron, fluoride, and dissolved solids and high
hardness in ground water are encountered in several local
areas of the state. The following description of ground-wa-
ter quality in the various regions is based largely on work
done by Van Denburgh and Santos. 25) Additional water-qual-
ity data from more recent ground-water reports have been in-
corporated. Table 18 is a compilation of chemical analyses
of selected constituents in natural ground waters.
Coast Range Peninsula -
The quality of the ground water in the glacial outwash depos-
its is excellent. Total dissolved solids are less than 250
mg/1, and hardness is less than 120 mg/1. Marginal to poor
quality ground water is present in deep marine sedimentary
rocks of Tertiary age in the Upper Chehalis River basin. In
this area, total dissolved solids are greater than 500 mg/1
and silica concentrations are usually greater than 30 mg/1.
In the southeastern part of the Coast Range Peninsula region,
ground water has iron concentrations above the 0.3 mg/1 recom-
mended limit for drinking water set by the U. S. Public
Health Service (see Figure 33). Occurrences of saline ground
water in the coastal zones probably reflect "relict sea water"
resulting from incomplete flushing of salt water from rock
186
-------
CO
Table 18 . TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WASHINGTON. Concentrations in mg/l
(milligrams per liter). 26, 1 16 through 125)
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness
Location - Aquifer N R M
Coast Range Peninsula
Glaciofluvial and Alluvial Deposits 17 58 - 352 108
Puget Sound Province
Glacial and Alluvial Deposits 165 58-2,360 116
Lewis River Province
Glacial and Alluvial Deposits 10 67 - 310 137
Columbia Plateau
Yakima River Valley
Glacial and Alluvial Deposits 31 111- 559 195
Basalt 22 114- 416 214
Hanford
Unconsolidated Deposits 19 128 - 431 202
Basalt 8 119- 316 238
N R M
27 1.2 - 162 9.5
122 0.2 -990 5.4
11 0.8- 16 3.8
31 0.7- 26 6.0
22 1.2 - 106 6.0
19 1.5 - 26 6.8
8 3.2 - 12 6.8
N R M
28 3 - 244 56
119 8- 504 54
11 14- 162 60
31 42 - 338 107
22 39 - 250 84
19 80 - 274 115
8 20 - 144 85
N - Number of samples
R - Range
M - Median
-------
Table '8 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WASHINGTON. Concentrations in mg/l
(milligrams per liter). 26, 116 through 125)
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness (CaCO3)
Location - Aquifer
Columbia Plateau (Continued)
Walla Walla Basin
Gravel
Basalt
Southeastern Washington
!_, Sond and Gravel Deposits
oo Basalt
en
Northeastern Washington
Glacial and Alluvial Deposits
Basalt
N R M
5 139-555
15 106- 200 171
26 149 - 1,740 321
67 1 44 - 1 , 1 80 266
28 50 - 364 170
9 110- 285 188
N R M
8 3.5 - 25 8.2
22 0.2- 6.5 3.1
28 1.6 - 90 9.9
68 1.0 - 128 9.0
29 0.0 - 14 1.8
9 1.0- 13 3.0
N R M
7 70 - 219 176
20 36 - 142 72
28 92 - 1,220 180
70 8- 785 114
29 31 - 274 153
9 52 - 160 108
-------
03
Table 18 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WASHINGTON. Concentrations in mg/l
(milligrams per liter). 26/ 116 through 125)
Alkalinity
ron (Fe)
Sodium (Na)
Location - Aquifer N R M
Coast Range Peninsula
Glaciofluvial and. Alluvial Deposits 21 19-220 67
Puget Sound Province
Glacial and Alluvial Deposits 93 18-411 62
Lewis River Province
Glacial and Alluvial Deposits 11 16-103 52
Columbia Plateau
Yakima River Valley
Glacial and Alluvial Deposits 31 61-376 118
Basalt 21 70-202 134
Hanford
Unconsolidated Deposits 19 66-196 119
Basalt 8 61 - 177 129
N R M
23 0.00 - 1.20 0.20
102 0.00-6.4 0.12
11 0.00-4.8 0.02
22 0.00-0.76 0.04
18 0.00-0.79 0.06
19 0.00-5.2 0.03
8 0.02-0.68 0.06
N R M
20 2.6- 80 6.8
149 1.4 - 314 6.9
11 1.6- 9.3 5.1
31 3.5 - 58 14
22 7.2 - 54 24
19 3.5 - 34 17
8 7.1-80 26
-------
Table 18 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WASHINGTON. Concentrations in mg/l
(milligrams per liter). 26, 1 16 through 125)
Alkalinity (CaCO^) Iron
Location - Aquifer
Columbia Plateau (Continued)
Walla Walla Basin
Gravel
Basalt
Southeastern VVashington
Sand and Gravel Deposits
Basalt
Northeastern Washington
Glacial and Alluvial Deposits
Basalt
N
8
20
28
55
29
9
R
71 - 417
59 - 122
89 - 756
74 - 241
30 - 236
51 - 135
M
162
88
168
148
141
118
N
5 0.02
14 0.0
20 0.00
79 0.00
31 0.00
8 0.02
(Fe) Sodium (Na)
R M
-0.11
-0.77 0.04
-0.74 0.04
-2.4 0.07
-0.44 0.08
-0.20 0.04
N
5 5.4
11 6.2
19 3.7
73 8.4
29 1.7
8 5.3
R M
- 130
- 32 9.4'
- 376 22
- 86 32
- 34 4.2
- 26 14
-------
Table 18 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WASHINGTON. Concentrations in mg/l
(milligrams per liter). 26, 116 through 125)
Sulfate ($04)
Nitrate (NO3)
Silica (SiO2)
Location - Aquifer N R M
Coast Range Peninsula
Glaciofluvial and Alluvial Deposits 21 0.6 - 34 4.0
Puget Sound Province
Glacial and Alluvial Deposits 95 0.0 - 103 3.9
Lewis River Province
Glacial and Alluvial Deposits 11 0.6 - 41 7.4
Columbia Plateau
Yakima River Valley
Glacial and Alluvial Deposits 31 0.0-113 20
Basalt 22 0.1 - 46 3.0
Han ford
Unconsolidated Deposits 19 15 -113 27
Basalt 8 1.6-43 26
N R M
21 0.0 - 3.9 0.6
129 0.0-20 0.3
11 0.3-44 7.2
31 0.2 - 16 1.8
22 0.0 - 10 0.1
19 0-16 1.8
8 0.1 - 4.7 0.2
N R M
20 6.7-66 25
122 3.6-82 30
11 1 4 - 64 44
31 4.3-68 36
22 18 -65 51
19 4.3-70 31
8 18-64 52
-------
to
Table 18 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WASHINGTON. Concentrations in mg/l
(milligrams per liter). 26, 1 16 through 125)
Location - Aquifer
Columbia Plateau (Continued)
Walla Walla Basin
Gravel
Basalt
Southeastern Washington
Sand and Gravel Deposits
Basalt
Northeastern Washington
Glacial and Alluvial Deposits
Basalt
N
7
19
27
82
29
9
Sulfate (SO4)
R
3.5 - 38
1.8 - 31
9.1 - 811
0.8 - 468
3.7 - 109
4.5 - 24
M
16
5.3
29
24
15
11
N
7
17
27
76
29
9
Nitrate
R
0.2 -
0.0 -
0.0 -
0.0 -
0.0 -
0.0 -
(NO3) Silica
M
8.6 5.8
3.9 0.2
51 4.1
99 0.9
32 3.1
56 0.7
N
7 34
17 46
26 11
76 25
29 9
9 42
(Si02)
R
-58
-72
- 71
-79
.0 - 29
-52
M
43
56
42
50
15
45
-------
Table 18 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WASHINGTON. Concentrations in mg/l
(milligrams per liter). 26, 116 through 125)
Location - Aquifer
N
pH
R
M
Location - Aquifer
N
M
OJ
Coast Range Peninsula
Glaciofluvial and Alluvial Deposits
Puget Sound Province
Glacial and Alluvial Deposits
Lewis River Province
Glacial and Alluvial Deposits
Columbia Plateau
Yakima River Valley
Glacial and Alluvial Deposits
Basalt
19 6.1-9.2 6.9
141 6.0-9.2 7.5
10 6.2-8.0 7.0
30
19
7.0-8.3
7.1 - 9.2
7.8
7.8
Columbia Plateau (Continued)
Walla Walla Basin
Gravel
Basalt
Southeastern Washington
Sand and Gravel Deposits
Basalt
Northeastern Washington
Glacial and Alluvial Deposits
Basalt
17
71
24
9
7.3 -8.0
7.6 -8.2
7.4 - 8.1
7,4-8.7
6.7-9.4
7.2 - 7.9
7.9
8.0
7.8
7.8
Han ford
Unconsolidated Deposits
Basalt
19
7.4-8.3
7.5 - 9.2
7.8
7.8
-------
40 Ml.
Areas where ground water commonly
contains more than 250 mg/l of
dissolved solids
Areas where ground water commonly
contains 0.30 mg/l or more of iron
Figure 33. Washington - Dissolved solids and iron in ground water.
-------
materials following declines in sea level since Pleistocene
times. The saline water could also represent true connate
water that has been in the aquifer since its formation. 122)
Puget Sound Province -
The quality of most ground water in the Puget Sound province
is good to excellent. Most of the ground water contains less
than 150 mg/1 dissolved solids and is soft. Isolated inland
occurrences of water with large amounts of dissolved solids
are due to pumpage from aquifers in marine sedimentary de-
posits or incompletely flushed connate water. In the coastal
areas, saline ground water is present at depth, and upward
migration of saline water is possible as a result of pumping
from the shallow fresh-water aquifer.
Several areas in and adjacent to Puget Sound yield ground wa-
ter with concentrations of iron above the 0.3 mg/1 recommend-
ed limit. Silica is present in ground water in the range of
7 to 60 mg/1, but most values fall within the 25 to 40 mg/1
range. Ground water with high silica content usually occurs
in older and deeper aquifers. Iron concentrations are high
in ground water in the Everest area of Snohomish County. No
obvious relationship exists between aquifer depth, age, and
high iron concentrations, although proximity to Tertiary
rocks seems to be a factor in some places. 123) Peat sedi-
ments in deposits of Pleistocene and Recent age may also in-
directly contribute to iron-rich ground water. 116) in the
northern half of the province, ground water is moderately
hard (61 to 120 mg/1).
Lewis River Province -
The quality of most ground water in the Lewis River province
is excellent. Dissolved solids are generally less than 150
mg/1, and the hardness is usually less than 100 mg/1. Silica
in concentrations of more than 30 mg/1 is present in most
well waters. Local high iron concentrations occur.
Columbia Plateau -
Ground water of the Columbia Plateau varies in chemical char-
acter. In irrigated areas, the sedimentary deposits of Pleis-
tocene age that overlie the basalt contain ground water of
fairly poor quality as a result of irrigation returns. The
hardness of this ground water commonly exceeds 180 mg/1, and
the total dissolved solids are often above 500 mg/1. Else-
where, the dissolved solids are characteristically less than
250 mg/1.
195
-------
The chemical nature of ground water native to the Columbia
River basalt is rather uniform. It has a moderate dissolved
solids content of about 275 mg/1, with calcium, sodium, bi-
carbonate, and silica as the principal constituents. Much of
the ground water has a slight hydrogen sulfide odor. 15) The
silica ranges between 40 and 80 mg/1. Iron concentrations in
this aquifer are generally below 0.3 mg/1, but locally higher
concentrations do occur.
Many wells in the Pullman-Moscow area experience excessive
iron in ground water. 124) Deeper basalt aquifers sometimes
yield more mineralized water, but studies of the relation of
depth to quality show only some general differences. Water
at greater depths has less calcium, magnesium, and bicarbon-
ate but contains more sodium and potassium. 15) Sulfate in
the basalt ranges from 10 to 50 mg/1 and averages 20 mg/1.
Higher sulfate concentrations (50 to 250 mg/1) occur in the
upper zone of the basalt aquifer within the Columbia Basin
Irrigation Project area in Adams, Franklin, and Grant Coun-
ties. Ground water in the Walla Walla River basin is gener-
ally of excellent quality. It is low in mineral content,
and soft to moderately hard. 112)
At the Hanford Reservation, the ground-water quality in the
unconsolidated aquifer has changed as a result of radioactive
waste disposal. The average concentrations of some constitu-
ents in the ground water prior to significant disposal of
waste indicates a good quality water low in sulfates (21.5
mg/1), nitrates (2.2 mg/1), sodium (19.4 mg/1), and calcium
(28.6 mg/1). 121)
Northeast -
Ground water in the alluvial, glacial, and terrace deposits
along the Okanogan and Wenatchee Rivers is hard and contains
more than 250 mg/1 dissolved solids. Mineralization of
ground water increases with depth. In the eastern part of
the province, particularly in the Spokane River valley,
ground water in similar deposits usually contains less than
200 mg/1 dissolved solids and has a hardness less than 150
mg/1. The silica content of ground water is less than 30
mg/1. Long-term chemical quality records in the Spokane and
Curlew areas show no overall change in chemical character of
the ground water, although shallow ground water exhibits
slight year-to-year fluctuations as a result of irrigation.
Local problems of excessive iron occur in the Spokane area.
125)
196
-------
Wyoming
The quality of the ground water in Wyoming is variable. The
alluvial aquifers yield moderately hard to very hard water
(over 200 mg/1). Sandstone aquifers yield soft to very hard
water depending on depth, age, and closeness to recharge
areas. Sandstones of Cretaceous and Jurassic age generally
yield softer water than younger (Tertiary) or older (Pale-
ozoic) rocks. The median total dissolved solids of ground
water in unconsolidated aquifers and sandstones shallower
than 300 m (1,000 ft) is about 500 mg/1, equivalent to the
U. S. Public Health Service's recommended upper limit for
drinking water. In deeper aquifers, the median total dis-
solved solids concentration is over 2,000 mg/1. 4) Total
dissolved solids concentrations of ground water in various
aquifers are given in Table 7 in Section IV of this report.
A compilation of chemical analyses of selected constituents
in natural ground waters is shown in Table 19.
More than 60 percent of Wyoming is underlain by saline ground
water. Figure 34 shows the depth to ground water containing
more than 1,000 mg/1 dissolved solids. A short description
of ground-water quality in the various basins in given below.
Green River Basin -
The quality of ground water in the Green River basin varies
from very poor to excellent. Water in the sand and gravel
deposits and in the more permeable sandstone of the Wasatch
Formation near the surface in the northern two-thirds of Sub-
lette County generally contains less than 500 mg/1 total dis-
solved solids. In southern Sublette County and further south,
water ranging from 500 to 3,500 mg/1 in dissolved solids is
generally available from at least one aquifer; other aqui-
fers may contain more highly mineralized water.
A deltaic sandstone in the New Fork Tongue of the Wasatch
Formation extending some 1,300 to 3,100 sq km (500 to 1,200
sq mi), contains several artesian zones. This aquifer, over-
lain by the Green River Formation which contains exploitable
oil shales, is available as a source of water for the oil
shale industry. The water, however, is not potable because
of excessive concentrations of fluoride (6.5 to 14.0 mg/1)
and total dissolved solids (690 to 2,200 mg/1). 20)
Near Farson and Edin in the northern part of the Green River
basin, black artesian ground water has been encountered in
permeable oil shales of the Green River Formation. The black
color is caused by organic acids dissolved in a sodium bicar-
bonate solution. The origin of the ground water is not
197
-------
Table 19 . TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WYOMING. Concentrations in mg/l
(milligrams per liter). 22' 13° throu9h 133)
Dissolved Solids
(residue on evaporation at 180°C)
Chloride (Cl)
Hardness (CaCO3)
Location and Rock Type
Northeast
Alluvium
Wasatch Formation
Fort Union Formation
Lance Formation
Parkman Sandstone
Frontier Formation
Inyan Kara Group
Minnelusa Formation
Platte River Basin
Alluvium
Terrace Deposits
Arikaree Formation
Brule Formation
Bighorn River Basin
Al luvium
Terrace Deposits
Wind River Formation
Frontier Formation
Chugwater Group
Tensleep Sandstone
N
16
17
19
12
8
7
28
25
13
8
18
8
34
22
39
8
4
2
82
281
484
450
550
390
218
551
260
234
176
251
256
265
203
1,170
3,040
801
R
- 3,340
- 6,620
- 3,250
- 3,060
- 22,060
- 24,950
- 18,706
- 199,782
692
786
831
616
- 4,600
- 3,310
- 5,000
- 13,071
- 41,505
- 2,567
M
1,240
890
1,310
1,310
4,880
8,040
1,370
4,350
390
495
287
399
1,040
956
872
2,138
-
—
N
16
17
19
12
8
7
28
25
13
8
18
7
28
23
39
10
7
8
0.0
2.0
3.7
4.0
1.6
1.7
2.0
1.0
3.0
4.0
2.0
4
0.1
0.0
0
4
26
8
R
194
45
63
110
- 11,700
- 13,800
- 10,000
- 120,000
19
19
119
52
95
44
416
- 7,500
- 15,850
920
M
6.8
10
14
10
1,720
4,650
49
310
9.2
13
12
9
17
9.5
20
92
6,200
42
N
16
17
19
12
2
2
8
6
13
8
19
7
34
23
36
4
1
2
R
38 - 1 , 240
12 -3,310
16 - 2,310
12 - 1,710
212- 407
174- 731
62 - 1 , 340
431 -2,840
147 - 452
123 - 484
69 - 556
110- 311
138 - 1,280
68 - 1,420
3 - 1,810
8 - 126
157
556 - 573
M
326
461
55
92
-
-
196
-
187
288
170
202
412
384
88
-
-
—
N - Number of samples
R - Range
M - Median
-------
Location and Rock Type
Southwest
Alluvium
Gravel Deposits
Laney Shale
Tipton Shale
Wasarch Formation
(residue
N
16
8
14
7
46
(milligrams per liter). y
Dissolved Solids
on evaporation at 180°C) Chloride (Cl) Hardness (CaCC>3)
R MNR MNRM
209- 3,210 484 18 3.5- 272 18 17 3-1,220 228
65 - 2,460 310 8 0.9 - 726 6.8 6 52 - 983
562- 3,450 1,380 14 4.9- 394 22 14 2-2,020 214
555- 3,700 781 7 16 - 1,700 26 2 6 - 18
215- 3,590 869 47 0.7- 3,070 18 46 0-1,610 36
-------
Table 19 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WYOMING. Concentrations in mg/\
(milligrams per liter). 22' 13° ^rough 133)
Alkalinity (as CaCOg)
Iron (Fe)
Sodium (Na)
Location and Rock Type
Northeast
Alluvium
Wasatch Formation
Fort Union Formation
Lance Formation
Parkman Sandstone
Frontier Formation
NJ Inyan Kara Group
:? Minnelusa Formation
Platte River Basin
Alluvium
Terrace Deposits
Arikaree Formation
Brule Formation
Bighorn River Basin
Alluvium
Terrace Deposits
Wind River Formation
Frontier Formation
Chugwater Group
Tensleep Sandstone
N
16
16
15
11
8
7
24
20
9
4
14
4
25
19
38
10
6
8
48
138
110
228
271
144
152
130
134
134
108
154
154
129
18
136
111
132
R
- 601
- 753
- 1 , 943
- 1,123
-2,075
-3,165
-1,730
-1,.091
- 285
- 254
- 284
- 456
- 503
- 423
- 385
-6,703
-2,481
-1,279
M
322
392
610
451
895
1,300
466
240
217
-
163
-
307
317
125
848
-
365
N
15
17
19
12
2
2
7
4
13
8
18
8
23
20
25
2
1
—
R
0.00 - 11
0.03 -25
0.08 - 9.0
0.00 - 8.6
0.22 - 1.3
0.02 - 2.9
0.01 - 5.5
0.05 - 0.55
0.02- 1.2
0.01 - 0.11
0.00 - 0.27
0 - 1.1
0.0 - 1.3
0.01 - 0.34
0.02 - 3
0.20 - 0.21
0.50
—
M
1.3
0.26
0.26
0.10
-
-
0.74
-
0.03
0.02
0.04
0.02
0.20
0.10
0.28
-
-
~
N
16
17
19
12
2
2
7
3
11
6
18
5
31
16
38
4
-
2
R
4.7 -
3.4-
39 -
150 -
29 -
74 -
56 -
4.1 -
13 -
11 -
7.5 -
32 -
7 -
24 -
15 -
435 -
-
49
970
800
943
922
366
299
486
29
77
75
126
122
1,100
460
1,500
772
M
178
202
400
360
-
-
70
~
34
-
29
-
93
136
260
-
-
~
-------
Table 19 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WYOMING. Concentrations in mg/l
(milligrams per liter). 22, 130 through 133)
Location and Rock Type
Southwest
Alluvium
Gravel Deposits
Laney Shale
Tipton Shale
Wasatch Formation
Alkal
N
18
6
14
7
47
inity (as
R
103 -
80 -
110-1,
221 - 1,
0-1,
CaCO3
533
568
607
427
410
)
M
242
-
266
298
295
N
8
7
6
2
34
Iron (Fe)
R
0.0 - 7.0
0.02 - 0.40
0.0 - 0.77
0.05 - 0.14
0.00 -61
M
0.78
0.03
-
-
0.11
N
7
7
8
7
37
Sodium
R
16 -
2.8 -
99 -
217 -
17 -
(Na)
265
500
1,290
1,470
1,190
M
67
21
240
298
258
-------
Table 19 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WYOMING. Concentrations in mg/l
(milligrams per liter). 22, 130 through 133)
Location and Rock Type
Northeast
Alluvium
Wasatch Formation
Fort Union Formation
Lance Formation
Parkman Sandstone
Frontier Formation
t^j In/an Kara Group
° Minnelusa Formation
NJ
Platte River Basin
Alluvium
Terrace Deposits
Arikaree Formation
Brule Formation
Bighorn River Basin
Alluvium
Terrace Deposits
Wind River Formation
Frontier Formation
Chugwater Group
Tensleep Sandstone
N
16
17
19
12
8
7
25
25
13
8
19
7
28
23
39
10
7
8
Sulfate
R
3.3 -
1.3 -
0.3 -
0.3 -
39 -
0 -
15 -
203 -
14 -
8.6 -
0.1 -
15 -
47 -
20 -
23 -
0 -
1,830 -
67 -
(SO4) Nitrate (NOa) pH
M N R M N R M
1,950 474 14 0.0 - 3.5 0.4 16 6.7-8.2 7.6
4,080 284 13 0.0 - 19 3.8 17 6.8-8.3 7.5
1,870 55 13 0.0 - 11 1.0 19 7.0-8.8 7.9
1,780 508 12 0.0 - 13 0.4 12 7.0-8.5 7.8
1,312 266 2 0.0 - 4.3 - 2 7.8-8.1
1,250 70 2 0.4 - 3.2 - 2 7.1 - 8.1
1,413 292 7 0.0 - 13 0.1 7 7.3-8.0 7.6
5,452 1,890 3 0.1 - 2.2 - 4 7.0-7.5
296 61 13 0.1 - 19 5.5 12 7.3-8.0 7.6
280 158 8 0.16- 28 3.4 7 7.3-8.1 7.7
328 27 17 0.0 - 26 6.4 19 6.8-8.4 7.7
197 33 7 0.6 - 29 16 6 7.3 - 8.4
2,450 671 28 0.0 - 10 2.2 34 7.2-8.2 7.7
1,880 390 23 0.6 - 40 13 23 7.4-8.4 7.8
3,250 440 38 0.0 - 44 0.3 39 6.8-9.7 7.9
2,700 68 3 0.0 - 10 - 4 7.9-9.1
12,139 8,890 1 2.7 - 1 8.0
2,296 990 1 0.1 1 7.3
-------
Table 19 (Continued). TABULATION OF SELECTED CHEMICAL ANALYSES OF GROUND WATER IN WYOMING. Concentrations in mg/1
(milligrams per liter). 22, 130 through 133)
M
O
CO
Location and Rock Type
Southwest
Al luvium
Gravel Deposits
Laney Shale
Tipton Shale
Wasatch Formation
N
17
8
14
7
47
Sulfate
7.4
7.2
65
2.1
0.2
(S04)
R
- 1,760
695
- 2,140
226
- 2,020
M
170
28
456
157
195
N
16
6
13
2
44
Nitrate
R
0.0 -
0.1 -
0.0 -
0.0 -
0.0 -
(N03)
M
1.9 0.6
14
126 1.0
0.2
10 0.1
N
18
8
14
7
48
Pit
R
6.8 -8.8
7.3 -8.1
7.2 -9.0
8.3 -9.3
4.4 -9.7
M
7.4
7.6
8.0
9.1
8.2
-------
50 100 KM.
I I
50 Ml.
CHEYENNE;
/ »A
Depth to Saline Ground Water
feet meters
less than 500 150
500-1,000 150-300
more than 1,000 300
Figure 34. Wyoming - Depth to ground water containing more than 1,000 mg/l dissolved solids. '
-------
clear, but the black water may be original lake water incor-
porated in the sediments during recession of an ancient lake
in the geologic past. 130)
In general, ground water in the Green River basin becomes
more mineralized with increasing depth, and below 600 m
(2,000 ft), total dissolved solids over 1,000 mg/1 may be ex-
pected. Some exceptions occur in the Great Divide and Wash-
akie Basins, where zones of good quality water in the Wasatch,
Fort Union, and Lance Formations are overlain by zones of
poorer quality water.
The sand and gravel deposits in the north and southwest, in
the Wasatch Formation in the north, and other Tertiary rocks
in the north and northeast, would yield water suitable for ir-
rigation, if adequate quantities could be obtained. Water in
the Green River and Wasatch Formations in the southern two-
thirds of the basin is not suitable for irrigation because of
a high sodium content. Some of the ground water from the
Wasatch, Green River, and Bridger Formations is high in fluo-
ride. 129) in the Great Divide and Washakie Basins, ground
water having a concentration of less than 1,000 mg/1 of total
dissolved solids can be found in about one-third of the area;
elsewhere the water is poorer in quality. Locally excessive
concentrations of iron, sulfate, and fluoride occur in the
ground water. 128)
Snake River Basin -
Ground water is generally hard to very hard within Grand
Teton National Park. Some ground water is soft and has total
dissolved solids of less than 100 mg/1. Water from the allu-
vial deposits in the Star Valley contains less than 300 mg/1
of total dissolved solids. 131)
Bighorn River Basin -
Ground water in the alluvial deposits varies in concentration
from 250 to 4,000 mg/1 of total dissolved solids but gener-
ally contains less than 1,000 mg/1 of total dissolved solids.
The quality of ground water in the floodplain and terrace de-
posits is affected by irrigation returns. 132,133) Waterlog-
ging has occurred in many irrigated areas. Ground water from
the alluvial deposits below the Riverton Irrigation Project
area in the Wind River basin is highly mineralized and unsuit-
able for domestic and irrigation use. 134,135) in the Grey-
bull River-Dry Creek area, a direct correlation exists be-
tween sulfate concentrations and mineralization of ground wa-
ter. Concentrations of sulfate exceed 250 mg/1 in water from
two-thirds of the wells and springs, and are accompanied by
-------
concentrations of total dissolved solids of over 500 mg/1.
136)
In Sheridan County, water from the alluvium has a medium to
very high salinity hazard rating with a total dissolved sol-
ids concentration ranging from 272 to 2,060 mg/1. Iron and
sulfate concentrations are also above U. S. Public Health
Service recommended limits for drinking water. 137) Where
the quality of surface-water recharge is good, the alluvium
yields better quality water. Water from the Fort Union and
Wasatch Formations is hard and of poor quality. Methane gas
is produced together with water in many wells penetrating
coal beds in the two formations.
Northeastern Wyoming -
The quality of ground water varies greatly from area to area
according to aquifer, depth, nearness to recharge area, irri-
gation practices, and presence of evaporites in the subsur-
face. In the alluvial aquifers, the water is generally very
hard, mineralized, and contains high concentrations of iron.
Ground water in the alluvium is often of better quality in
the upstream areas where better quality recharge water is
available. In the river valleys, the ground-water quality
reflects the chemical characteristics of springs and seeps
from Tertiary and older aquifers that recharge the alluvium.
The dissolved solids of ground water from alluvium vary from
1,000 to 3,000 mg/1. 138)
The ground water from most consolidated formations is hard
and contains concentrations of iron, sulfate, and dissolved
solids in excess of U. S. Public Health Service recommended
limits for drinking water. Most ground water is suitable for
stock watering, but is of limited use for irrigation.
The Arikaree Formation is an important aquifer in Niobrara
County and furnishes moderate to large quantities of water to
wells. The hardness of the ground water from the Arikaree
Formation ranges from 165 to 340 mg/1, and dissolved solids
range from 230 to 535 mg/1. 139)
In the Gillette area, a rapidly developing industrial and
coal mining center, small quantities of water are available
from the Wasatch and Fort Union Formations. Water in the Fox
Hills sandstone of late Cretaceous age contains excessive
concentrations of dissolved solids. 140)
Platte River Basin -
The ground-water quality of the alluvial and terrace deposits
206
-------
is generally fair to good. The water is hard and the aqui-
fer is susceptible to degradation from irrigation returns
and from pollution on the land surface. Problems of water-
logging occur in the Wheatland Flats area. 141) In some
places, the ground water in floodplain deposits contains ex-
cessive concentrations of iron and nitrate. 142,143,144)
Water from aquifers of Tertiary age varies in quality. The
Ogallala Formation yields hard water satisfactory for most
domestic and stock uses. Water from the North Park, Browns
Park, Arikaree, and Battle Spring Formations is of fair to
good quality. Some local problems of excessive fluoride con-
centrations are reported in ground water from the Lance For-
mation. 142)
Ground water from the White River, Wasatch, and Fort Union
Formations is locally unsuitable for drinking. In the pre-
Tertiary sediments, ground water is of variable quality with
a range of total dissolved solids from 200 to 100,000 mg/1.
Ground-water quality is best near the recharge areas, but de-
teriorates toward the interior of the sedimentary basins.
207
-------
REFERENCES CITED
SECTION V
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U. S. Department of Health, Education and Welfare,
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2. Feth, J. H., and others, "Preliminary Map of the Con-
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9. Watson, I. C., and F. M. Heider, "Feasibility of Desalt-
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208
-------
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16. Whatcom County Regional Planning Council, "Comprehen-
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209
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23. Ralston, D. R., "Ground Water Resources of Northern
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25. Van Denburgh, A. S., and J. F. Santos, "Ground Water in
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26. Crist, M. A., "Selenium in Waters in and Adjacent to
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27. Chappell, W. R., "The Molybdenum Project," Duane F-1011,
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28. Scott, R. C., and F. B. Barker, "Data on Uranium and
Radium in Ground Water in the United States, 1954 to
1957," U. S. Geological Survey, Professional Paper 426,
1962.
29. Mullins, J. W., and J. L. Stein, "Evaluation of Tritium
in Ground and Surface Waters of the Western United
States, April 1968-December 1969," Radiation Data and
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30. Gamewell, Richard, "Radium in Ground Waters in Pueblo
County, Colorado, 1972-1973," Colorado Department of
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31. Goldblatt, E. L., A. S. Van Denburgh, and R. A. Mars-
land, "The Unusual and Widespread Occurrence of Arsenic
in Well Waters of Lane County, Oregon," Lane County
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32. Department of Environmental Quality, Wyoming-1974,
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33. Waring, G. A., "Thermal Springs of the United States
and Other Countries of the World - A Summary," U. S.
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34. Boettcher, A. J., "Ground-Water Occurrence in Northern
and Central Parts of Western Colorado," Colorado Water
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210
-------
35. Young, H. W., and J. C. Mitchell, "Geothermal Investi-
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36. Nichols, C. R., and others, "Geothermal Water and Power
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37. Anderson, D. N., and L. H. Axtell, "Geothermal Over-
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38. Federal Water Pollution Control Administration, "Ground
Water Pollution in the Middle and Lower South Platte
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39. Hofstra, W. E., T. J. Major, and R. R. Luckey, "Hydro-
geologic Data for the Northern High Plains of Colorado,"
Colorado Water Conservation Board, Basic-Data Release
23, 1972.
40. Water Resources Division, "Water Resources Data for
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41. Scott, R. C., and P. T. Voegeli, Sr., "Radiochemical
Analyses of Ground and Surface Water in Colorado, 1954-
1961," Colorado Water Conservation Board, Basic-Data
Report 7, 1961.
42. McConaghy, J. A., and others, "Hydrogeologic Data of
the Denver Basin, Colorado," Colorado Water Conserva-
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43. Emery, P. A., R. J. Snipes, and J. M. Dumeyer, "Hydro-
logic Data for the San Luis Valley, Colorado," Colorado
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44. Ficke, J. F., J. B. Weeks, and F. A. Welder, "Hydro-
logic Data from the Piceance Basin, Colorado," Colorado
Department of Natural Resources, Basic-Data Release 31,
1974.
45. McGovern, H. E., and D. L. Coffin, "Potential Ground-
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High Plains," Colorado Water Conservation Board, Circu-
lar 8, 1963.
211
-------
46. Coffin, D. L. , and others, "Geohydrology of the Pice-
ance Creek Structural Basin Between the White and Colo-
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47. Dion, N. P., "Some Effects of Land-Use Changes on the
Shallow Ground-Water System in the Boise-Nampa Area,
Idaho," Idaho Department of Water Administration, Water
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48. Stevens, P. R., "Effect of Irrigation on Ground Water
in Southern Canyon County, Idaho," U. S. Geological
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49. Walton, W. C., "Ground-Water Resources of Camas Prairie,
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50. Young, H. W., and W. A. Harenberg, "A Reconnaissance of
the Water Resources in the Pahsimeroi River Basin, Ida-
ho," Idaho Department of Water Administration, Water
Information Bulletin 31, 1973.
51. Dion, N. P., "Hydrologic Reconnaissance of the Bear
River Basin in Southeastern Idaho," Idaho Department of
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52. Dyer, K. L., and H. W. Young, "A Reconnaissance of the
Quality of Water from Irrigation Wells and Springs in
the Snake Plain Aquifer, Southeastern Idaho," U. S.
Geological Survey, Open-file Report, 1971.
53. Robertson, J. B., Robert Schoen, and J. T. Barraclough,
"The Influence of Liquid Waste Disposal on the Geochem-
istry of Water at the National Reactor Testing Station,
Idaho: 1952-70," U. S. Geological Survey, Open-file Re-
port, 1974.
54. Stevens, P. R., "Ground-Water Problems in the Vicinity
of Moscow, Latah County, Idaho," U. S. Geological Sur-
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55. Jones, R. W., and S. H. Ross, "Detailed Ground-Water
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212
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56. Ralston, D. R., and S. L. Chapman, "Ground-Water Re-
source of the Mountain Home Area, Elmore County, Idaho,"
Idaho Department of Reclamation, Water Information
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57. Littleton, R. T., and E. G. Crosthwaite, "Ground-Water
Geology of the Bruneau-Grand View Area, Owyhee County,
Idaho," U. S. Geological Survey, Water-Supply Paper
1460-D, 1957.
58. Ralston, D. R., and N. C. Young, "Water Resources of
the Twin Falls Tract, Twin Falls County, Idaho," Idaho
Department of Water Administration, Water Information
Bulletin 22, 1971.
59. Fowler, K. H., "Preliminary Report on Ground Water in
the Salmon Falls Area, Twin Falls County, Idaho," U. S.
Geological Survey, Circular 436, 1960.
60. Walker, E. H., and others, "The Raft River Basin, Idaho-
Utah, as of 1966: A Reappraisal of the Water Resources
and Effects of Ground-Water Development," Idaho Depart-
ment of Water Administration, Water Information Bulle-
tin 19, 1970.
61. Chapman, S. L., and N. C. Young, "Water Resources of
Western Oneida and Southern Power Counties, Idaho,"
Idaho Department of Water Administration, Water Informa-
tion Bulletin 25, 1972.
62. Norvitch, R. F., and A. L. Larson, "A Reconnaissance of
the Water Resources in the Portneuf River Basin, Idaho,"
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63. Schoen, Robert, "Hydrochemical Study of the National
Reactor Testing Station, Idaho," 24th International
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64. Feltis, R. D., "Geology and Water Resources of Eastern
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and Geology, Bulletin 87, 1973.
65. Zimmerman, E. A., "Geology and Ground-Water Resources
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213
-------
66. Van Lewen, M. C., and N. J. King, "Prospects for Devel-
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67. Zimmerman, E. A., "Preliminary Report on the Geology
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68. Swenson, F. A., and H. A. Swenson, "Geology and Ground-
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69. Osterkamp, W. R. , "Occurrence of Ground Water in the
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70. Alverson, D. C., "Geology and Hydrology of the Fort
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71. Zimmerman, E. A., "Preliminary Report on the Geology
and Ground-Water Resources of Parts of Musselshell and
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72. Groff, S. L., "Reconnaissance Ground-Water Studies,
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73. Groff, S. L., "Reconnaissance Ground-Water Studies,
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74. Zimmerman, E. A., "Geology and Water Resources of the
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75. Moulder, E. A., F. A. Kohout, and E. R. Jochens,
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214
-------
76. Torrey, A. E., F. A. Swenson, and H. A. Swenson,
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77. Taylor, O. J., "Ground-Water Resources Along Cedar
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78. Taylor, 0. J., "Ground-Water Resources of the Northern
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79. Hamilton, L. J., and Q. F. Paulson, "Geology and Ground-
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80. Moulder, E. A., and others, "Geology and Ground-Water
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81. McMurtrey, R. G., and R. L. Konizeski, "Progress Report
on the Geology and Ground-Water Resources of the East-
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82. Zimmerman, E. A., "Water Resources of the Cut Bank Area,
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85. Lorenz, H. W., F. A. Swenson, and H. A. Swenson, "Geol-
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86. Lorenz, H. W., R. G. McMurtrey, and H. A. Swenson,
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Paper 1360-C, 1956.
215
-------
87. Hackett, 0. M., and others, "Geology and Ground-Water
Resources of the Gallatin Valley, Gallatin County, Mon-
tana," U. S. Geological Survey, Water-Supply Paper 1482,
1960.
88. McMurtrey, R. G., R. L. Konizeski, and Alex Brietkrietz,
"Geology and Ground-Water Resources of the Missoula Ba-
sin, Montana," Montana Bureau of Mines and Geology,
Bulletin 47, 1965.
89. Coffin, D. L., and K. R. Wilke, "Water Resources of the
Upper Blackfoot River Valley, West-Central Montana,"
Montana Department of Natural Resources and Conserva-
tion, Technical Report Series No. 1, 1971.
90. Botz, M. K., "Hydrogeology of the Upper Silver Bow
Creek Drainage Area, Montana," Montana Bureau of Mines
and Geology, Bulletin 75, 1969.
91. Konizeski, R. L., Alex Brietkrietz, and R. G. McMurtrey,
"Geology and Ground-Water Resources of the Kalispell
Valley, Northwestern Montana," Montana Bureau of Mines
and Geology, Bulletin 68, 1968.
92. McMurtrey, R. G., and others, "Preliminary Report on
the Geology and Water Resources of the Bitterroot Val-
ley, Montana," Montana Bureau of Mines and Geology,
Bulletin 9, 1959.
93. Gosling, A. W., and E. F. Pashley, Jr., "Water Resources
of the Yellowstone River Valley, Billings to Park City,
Montana," U. S. Geological Survey, Hydrologic Investiga-
tions Atlas HA-454, 1973.
94. Montana Water Resources Board, "Ground Water in Mon-
tana," Inventory Series Report 16, 1969.
95. Piper, A. M., "Ground-Water Resources of the Willamette
Valley, Oregon," U. S. Geological Survey, Water-Supply
Paper 890, 1942.
96. Griffin, W. C., F. A. Watkins, Jr., and H. A. Swenson,
"Water Resources of the Portland, Oregon, and Van-
couver, Washington Area," U. S. Geological Survey, Cir-
cular 372, 1956.
97. Brown, S. G., "Problems of Utilizing Ground Water in the
West-Side Business District of Portland, Oregon," U. S.
Geological Survey, Water-Supply Paper 1619-0, 1963.
216
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98. Price, Don, "Geology and Water Resources in the French
Prairie Area, Northern Willamette Valley, Oregon,"
U. S. Geological Survey, Water-Supply Paper 1833, 1967,
99- Price, Don, "Ground Water in the Eola-Amity Hills
Area, Northern Willamette Valley, Oregon," U. S. Geo-
logical Survey, Water-Supply Paper 1847, 1967.
100. Hampton, E. R., "Geology and Ground Water of the
Molalla-Salem Slope Area, Northern Willamette Valley,
Oregon," U. S. Geological Survey, Water-Supply Paper
1997, 1972.
101. Frank, F. J., and N. A. Johnson, "Selected Ground-
Water Data in the Eugene-Springfield Area, Southern
Willamette Valley, Oregon," Oregon State Engineer's
Office, Ground-Water Report 14, 1970.
102. Frank, F. J., and N. A. Johnson, "Ground-Water Data in
the Corvallis-Albany Area, Central Willamette Valley,
Oregon," Oregon State Engineer's Office, Ground-Water
Report 17, 1972.
103. Robison, J. H., "Availability and Quality of Ground
Water in the Ashland Quadrangle, Jackson County, Ore-
gon," U. S. Geological Survey, Hydrologic Investiga-
tions Atlas HA-421, 1972.
104. Robison, J. H., "Availability and Quality of Ground
Water in the Medford Area, Jackson County, Oregon,"
U. S. Geological Survey, Hydrologic Investigations At-
las HA-392, 1971.
105. Robinson, J. W., and Don Price, "Ground Water in the
Prineville Area, Crook County, Oregon," U. S. Geologi-
cal Survey, Water-Supply Paper 1619-P, 1963.
106. Hogenson, G. M., "Geology and Ground Water of the Uma-
tilla River Basin, Oregon," U. S. Geological Survey,
Water-Supply Paper 1620, 1964.
107. Robison, J. H., "Hydrology of Basalt Aquifers in the
Hermiston-Ordnance Area, Umatilla and Morrow Counties,
Oregon," U. S. Geological Survey, Hydrologic Investi-
gations Atlas HA-387, 1971.
108. Hampton, E. R., and S. G. Brown, "Geology and Ground-
Water Resources of the Upper Grande Ronde River Basin,
Union County, Oregon," U. S. Geological Survey, Water-
Supply Paper 1597, 1964.
217
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109. Willamette Basin Task Force, "The Willamette Basin, Ap-
pendix B: Hydrology," Pacific Northwest River Basins
Commission, 1969.
110. Hampton, E. R., "Ground Water from Coastal Dune and
Beach Sands," U. S. Geological Survey, Professional
Paper 424-B, 1961, pp 204-206.
111. Brown, S. G., and R. C. Newcomb, "Ground-Water Re-
sources of the Coastal Sand-Dune Area North of Coos
Bay, Oregon," U. S. Geological Survey, Water-Supply
Paper 1619-D, 1963.
112. Newcomb, R. C., "Geology and Ground-Water Resources of
the Walla Walla River Basin, Washington-Oregon," Wash-
ington Department of Conservation, Division of Water
Resources, Water-Supply Bulletin 21, 1965.
113. Molenaar, Dee, and J. B. Noble, "Geology and Related
Ground-Water Occurrence, Southeastern Mason County,
Washington," Washington Department of Water Resources,
Water-Supply Bulletin 29, 1970.
114. Mundorff, M. J., J. M. Weigle, and G. D. Holmberg,
"Ground Water in the Yelm Area, Thurston and Pierce
Counties, Washington," U. S. Geological Survey, Circu-
lar 356, 1955.
115. Walters, K. L. , and G. E. Kimmel, "Ground-Water Occur-
rence and Stratigraphy of Unconsolidated Deposits, Cen-
tral Pierce County, Washington," Washington Department
of Water Resources, Water-Supply Bulletin 22, 1968.
116. Luzier, J. E., "Geology and Ground-Water Resources of
Southwestern King County, Washington," Washington De-
partment of Water Resources, Water-Supply Bulletin 28,
1969.
117. Liesch, B. A., C. E. Price, and K. L. Walters, "Geology
and Ground-Water Resources of Northwestern King County,
Washington," Washington Department of Conservation,
Division of Water Resources, Water-Supply Bulletin 20,
1963.
118. Easterbrook, D. J., and H. W. Anderson, Jr., "Pleisto-
cene Stratigraphy and Ground-Water Resources of Island
County, Washington," Washington Department of Water Re-
sources, Water-Supply Bulletin 25, Parts I and II,
1968.
218
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119. Eddy, P. A., "Preliminary Investigation of the Geology
and Ground-Water Resources of the Lower Chehalis River
Valley and Adjacent Areas, Grays Harbor County, Washing-
ton," Washington Department of Conservation, Division
of Water Resources, Water-Supply Bulletin 30, 1966.
120. Eliason, J. R., "Earth Sciences Waste Disposal Investi-
gations - July-December 1966," Battelle-Northwest Lab-
oratories, Publication 432, 1967.
121. Newcomb, R. C., J. R. Strand, and F. J. Frank, "Geology
and Ground-Water Characteristics of the Hanford Reser-
vation of the U. S. Atomic Energy Commission, Washing-
ton," U. S. Geological Survey, Professional Paper 717,
1972.
122. Walters, K. L., "Reconnaissance of Sea-Water Intrusion
Along Coastal Washington, 1966-68," Washington Depart-
ment of Ecology, Water-Supply Bulletin 32, 1971.
123. Noble, J. B., and E. F. Wallace, "Geology and Ground-
Water Resources of Thurston County, Washington," Wash-
ington Division of Water Resources, Water-Supply Bulle-
tin 10, 1966.
124. Walters, K. L., "Reconnaissance of Geology and of
Ground-Water Occurrence in Whitman County, Washington,"
Washington Department of Water Resources, Water-Supply
Bulletin 26, 1969.
125. Cline, D. R., "Ground-Water Resources and Related Geol-
ogy, North-Central Spokane and Southeastern Stevens
Counties of Washington," Washington Department of Wa-
ter Resources, Water-Supply Bulletin 27, 1969.
126. State Engineer's Office, "Water and Related Land Re-
sources of the Platte River Basin, Wyoming," Wyoming
Water Planning Program Report 9, 1971.
127. State Engineer's Office, "Water and Related Land Re-
sources of the Bighorn River Basin, Wyoming," Wyoming
Water Planning Program Report 11, 1972.
128. Welder, G. E., and L. J. McGreevy, "Ground-Water Recon-
naissance of the Great Divide and Washakie Basins and
Some Adjacent Areas, Southwestern Wyoming," U. S. Geo-
logical Survey, Hydrologic Investigations Atlas HA-219,
1966.
219
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129. Welder, G. E., "Ground-Water Reconnaissance of the
Green River Basin, Southwestern Wyoming," U. S. Geolog-
ical Survey, Hydrologic Investigations Atlas HA-290,
1968.
130. Dana, G. F., and J. W. Smith, "Black Trona Water,
Green River Basin," 25th Field Conference, Wyoming Geo-
logical Association Guidebook, 1973.
131. State Engineer's Office, "Water and Related Land Re-
sources of the Snake River Basin, Wyoming," Wyoming
Water Planning Program Report 12, 1972.
132. Swenson, F. A., and W. K. Bach, "Ground-Water Resources
of the Paintrock Irrigation Project, Wyoming," U. S.
Geological Survey, Circular 96, 1951.
133. McGreevy, C. J., and others, "Ground-Water Resources of
the Wind River Indian Reservation, Wyoming," U. S. Geo-
logical Survey, Water-Supply Paper 1576, 1969-
134. Morris, D. A., and others, "Ground-Water Resources of
Riverton Irrigation Project Area, Wyoming," U. S. Geo-
logical Survey, Water-Supply Paper 1375, 1959.
135. Whitcomb, H. A., and others, "Ground-Water Resources
and Geology of Northern and Central Johnson County,
Wyoming," U. S. Geological Survey, Water-Supply Paper
1806, 1966.
136. Robinove, C. J., and R. H. Langford, "Geology and
Ground-Water Resources of the Greybull River-Dry Creek
Area, Wyoming," U. S. Geological Survey, Water-Supply
Paper 1596, 1963.
137. Whitcomb, H. A., and M. E. Lowry, "Ground-Water Re-
sources and Geology of the Wind River Basin Area, Cen-
tral Wyoming," U. S. Geological Survey, Hydrologic In-
vestigations Atlas HA-270, 1968.
138. Whitcomb, H. A., and D. A. Morris, "Ground-Water Re-
sources and Geology of Northern and Western Crook
County, Wyoming," U. S. Geological Survey, Water-Supply
Paper 1698, 1964.
139. Whitcomb, H. A., "Ground-Water Resources and Geology of
Niobrara County, Wyoming," U. S. Geological Survey,
Water-Supply Paper 1788, 1965.
220
-------
140. Littleton, R. T., "Ground-Water Conditions in the
Vicinity of Gillette, Wyoming," U. S. Geological Sur-
vey, Circular 76, 1950.
141. Morris, D. A., and H. M. Babcock, "Geology and Ground-
Water Resources of Platte County, Wyoming," U. S. Geo-
logical Survey, Water-Supply Paper 1490, 1960.
142. Rapp, J. R., and others, "Geology and Ground-Water Re-
sources of Goshen County, Wyoming," U. S. Geological
Survey, Water-Supply Paper 1377, 1957.
143. Lowry, M. E., and M. A. Crist, "Geology and Ground-
Water Resources of Laramie County, Wyoming," U. S.
Geological Survey, Water-Supply Paper 1834, 1967.
144. Bjorklund, L. J., "Geology and Ground-Water Resources
of the Upper Lodgepole Creek Drainage Basin, Wyoming,"
U. S. Geological Survey, Water-Supply Paper 1483, 1959.
221
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SECTION VI
SOURCES OF GROUND-WATER CONTAMINATION
INTRODUCTION
In previous sections of this report, the general geologic
and hydrologic character of the project area was described.
In addition, a description of the natural ground-water qual-
ity was presented including many of the naturally occurring
ground-water problems. In this section, a discussion of
ground-water pollution or ground-water contamination prob-
lems is presented. The terms "pollution" and "contamination"
are synonymous and mean the degradation of natural water
quality as a result of man's activities to the extent that
its usefulness is impaired. There is no implication of any
specific limits (such as those in the U. S. Public Health
Service drinking water standards), as the degree of permis-
sible pollution depends upon the intended end use, or uses,
of the water.
Concern about potential pollution of ground water in the na-
tion was expressed by investigators from the U. S. Geologi-
cal Survey as much as 70 years ago. 1) Since that time a
number of studies have been conducted pertaining to ground-
water contamination. 2,3,4) However, until recent years,
government agencies at all levels were primarily concerned
with surface-water contamination, and only slight attention
was given to ground-water contamination. The more apparent
loss of rivers and lakes as water supply sources and as rec-
reation areas always initiated quicker public action than
the more obscure degradation of a ground-water reservoir.
Only when a regional ground-water supply is threatened by
pollution from septic tanks or discharge of toxic wastes, or
when a surface discharge point is contaminated, are controls
recommended and implemented.
As man's activities consume greater amounts of land and as
population and industry increase, greater volumes of ground
water are subject to potential contamination. Control and
prevention of ground-water contamination are required to
safeguard this vital water source for future generations.
Movement of Waste Fluids
To understand the health and other hazards associated with
ground-water contamination, some familiarity with the basic
principles of movement of contaminants in a ground-water
body is necessary. Ground water can simply be described as
222
-------
water contained in the saturated pore spaces and fractures
of hard rocks and sediments beneath the land surface. It
does not exist in a static condition but is constantly in
motion. The rate of ground-water movement is highly vari-
able both vertically and horizontally, and may vary from
meters per day to centimeters per day or less. For example,
in fractured crystalline rock the movement might be on the
order of tens of meters per day, whereas in unconsolidated
material it might be a few centimeters per day.
The configuration and slope of the water table are important
considerations in estimating the directions and rates of
travel-of wastes in the subsurface environment. Contami-
nants dumped in an area where the water table is practically
flat and where little movement of ground water is occurring
will tend to stay in place. On the other hand, it should be
kept in mind that low gradients can be associated with high
aquifer transmissivities in a given area, and high gradients
with low transmissivities. Where transmissivities are great,
the pollutant can move rapidly in spite of a relatively flat
water table.
The thickness and composition of the unsaturated zone overly-
ing the saturated zone are also important factors. Espe-
cially in cases of biological contamination, a thick unsat-
urated zone of fine-grained soil can adsorb and filter some
or all of the pollutants before they can be introduced into
the ground-water body itself..
Once at the top of the water table, fluid wastes generally
will enter the ground-water system with only minor mixing
with native ground water or will float (hydrocarbons for in-
stance) on top of the saturated zone. Figure 35 shows a
typical case involving the percolation of contaminants
through the unsaturated zone into a water-table aquifer.
The contaminant will then move with the ground water toward
its ultimate discharge point, which commonly is a spring or
a river. Frequently, however, ground-water flow patterns
are modified because of pumping from nearby wells. In such
cases, the hydraulic gradient or slope of the water table is
toward such a well, and the contaminants converge upon the
center of pumping and emerge in the well discharge. In most
cases, this is exactly how ground-water pollution is dis-
covered.
Under natural conditions and in the absence of pumping, wa-
ter-table aquifers in the more humid portions of the study
region discharge ground water continuously into a nearby
surface-water body such as a lake or river. Thus, the
ground water is entering the lake or stream and the aquifer
223
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NJ
DISPOSAL POND
SOURCE OF CONTAMINANTS
PERCOLATION THROUGH
UNSATURATEO ZONE
_r;_-CONFINING BED
Figure 35. Movement of contaminated ground water beneath leaky disposal pond.
-------
itself cannot be contaminated by wastes carried by the
stream. When a well is put in operation in such an aquifer
near a stream, however, ground-water levels are lowered and
the hydraulic gradient between the well and river may be re-
versed, causing surface water to flow toward the well. If
the stream is polluted, contaminated river water may thereby
be induced to flow to the well. This situation is shown on
Figure 36.
According to the laws governing fluid movement in saturated
material, the direction of ground-water flow will always be
toward points where the total hydraulic head is lowest. In
many parts of the Northwest, saline ground water in deep
aquifers is under high artesian heads, and it can be induced
to move upward into fresh-water aquifers where heads are
lower. An example would be the situation in which two zones
are interconnected through abandoned or improperly sealed
wells, as shown on Figure 37.
Sources of Ground-Water Contamination
A wide variety of harmful substances is regularly introduced
into subsurface formations and aquifers of the Northwest.
These substances enter ground-water supplies by direct in-
jection through wells, by percolation of liquids spilled at
the land surface or leached from soluble solids at the sur-
face, by leaking or broken sewers and pipelines, by downward
seepage from waste lagoons, and by infiltration of polluted
surface water into the ground. To the list should be added
contamination of ground water caused by infiltration of irri-
gation return water, seawater encroachment, and upward coning
of salty ground water into fresh-water aquifers.
One recognized threat to ground-water quality comes from im-
properly designed landfills. Rainfall entering the landfill
through its exposed surface comes in contact with the refuse
and dissolves organic and inorganic compounds to form a con-
centrated solution called leachate. The leachate then perco-
lates downward to contaminate an underlying aquifer.
Septic tanks, which are in use in all unsewered communities
and rural areas of the Northwest, are other sources that
have caused measurable pollution.
Disposal of industrial wastes in pits or lagoons is another
widespread practice. When improperly constructed, such la-
goons can leak untreated wastes containing such constituents
as hexavalent chromium, cadmium, cyanide, and caustic soda
into the subsurface.
225
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PUMP
i\J
INJ
CTl
CONTAMINATED
SURFACE WATER
ORIGINAL WATER TABLE
PUMPING WATER LEVEL
AQUIFER
Figure 36. Movement of contaminated surface water to a pumping water well. '
-------
PUMPING
FRESH WATER WELL
ABANDONED AND IMPROPERLY SEALED
OPEN HOLE
NJ
PIEZOMETRIC SURFACE
WATER TABLE
FRESH WATER AQUIFER
_-_:-_ CONFINING BED -__—_-
SALINE WATER AQUIFER
CONFINING BED-
Figure 37. Movement of deep saline ground water into a fresh-water aquifer by means of an improperly sealed open hole.5)
-------
Percolation of liquids spilled at the land surface can be a
serious threat if the surficial materials are permeable and
allow downward percolation. Storage of chemicals, chemical
wastes, petroleum products or radioactive waste fluids in
steel or concrete tanks also presents a potential hazard be-
cause corrosion of the metal or cracking of the concrete may
ultimately permit seepage of contaminants into an aquifer.
Leaching of soluble solids stored on the land surface is
still another practice that can be responsible for contami-
nation of ground water. Such incidents occur, for example,
where rain water dissolves soluble materials and enters the
ground from mine waste piles and stockpiles of highway de-
icing salt.
Deep-well disposal (disposal of liquid wastes through wells
into porous and permeable rock formations) by industry is
rare in the project area. However, a widespread agricul-
tural practice in Idaho is the disposal of irrigation sur-
face runoff water into shallow disposal wells. Such opera-
tions may threaten ground-water quality. Oil and gas wells
can also be a threat, for example, when injected oil field
brines pass into fresh-water aquifers as a result of cor-
roded or ruptured well casing.
Another kind of ground-water contamination takes place when
salt water encroaches and enters a fresh-water aquifer.
Salt-water intrusion occurs mainly in coastal areas where
pumping has decreased the natural seaward flow of fresh
ground water. However, it can also take place in inland
localities when pumping induces deep salty waters to cone
upward into fresh-water beds.
A summary of the principal sources of ground-water contamina-
tion in the Northwest is given in Table 20, in order of
their importance. The size of the areas affected and the
future trend in rate of new occurrences have also been esti-
mated. It should be noted that the relative importance of a
particular source of ground-water contamination varies from
state to state. For instance, radioactive waste disposal
takes place primarily in Idaho and Washington, while oil and
gas activities are limited to Colorado, Montana and Wyoming.
Sewage disposal and irrigation return flow are the two prin-
cipal sources of ground-water contamination in the Northwest.
Increased salinity in ground water caused by irrigation
practices is often of regional nature and affects a larger
volume of ground water than sewage disposal. However, dis-
charges from septic tanks and sewage treatment plants have a
greater impact on ground-water quality in more populated
areas and are therefore ranked above irrigation return flow
228
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Table 20.
PRINCIPAL SOURCES OF GROUND-WATER CONTAMINATION AND THEIR
RELATIVE IMPACT IN THE NORTHWEST.
Sources
Relative
importance
to region a)
Typical size
of area
affected b)
Estimated future
trend in rate of
new occurrences
c)
Septic systems
Sewage treatment plant discharge
Irrigation return flow
Dryland farming
Abandoned oil wells and test wells
Brine injection
Disposal wells
Surface impoundments
Mine drainage and mine tailings
Urban and industrial landfills
Radioactive waste disposal
Leaks and spills
Fertilizers and pesticides
Feed lots
Salt-water intrusion
Highway deicing salts
Mass burial of livestock
III
a) I - High
11 - Moderate
III - Low
b) I - Regional
II - Point source but can be regional in nature due to high density of individual
occurrences
III - Can affect adjacent properties
IV - Effluents contained within the boundaries of one property
c) I - Increase
II - No significant change
III - Decrease
229
-------
as sources of ground-water contamination.
Types of Contaminants
Biological contamination of ground water may occur when hu-
man or animal wastes enter an aquifer. Microorganisms pres-
ent in the wastes may be carried by the ground water into
nearby water wells and may cause disease when ingested. In-
organic chemical contamination differs from biological con-
tamination in several important ways. Most important are
the indestructibility of inorganic chemicals, the persist-
ence of the pollution created by their presence, and the
difficulty in their removal.
The U. S. Public Health Service has specified certain "maxi-
mum" concentrations for substances in drinking water (see
Appendix). Concentrations of such toxic elements as arsenic
and hexavalent chromium greater than 0.05 mg/1 would be
cause for rejection of the water supply if intended for
drinking purposes.
In the arid portion of the Northwest, inorganic chemical
contamination is of great concern to agricultural water
users. Generally, the quality criteria most often applied
relate to total salt concentration (total dissolved solids),
chloride, sodium, boron, and bicarbonate. Water low in
salts is usually the most desirable for irrigation, but some-
times only water containing several thousand milligrams per
liter of salts is available. High evaporation rates and
lack of adequate flushing may cause salt accumulation in the
root zone with a resulting decrease in crop yields. Reuse
and recycling of water for irrigation is a frequent source
of salt buildup in both surface and ground water.
Organic chemical contamination is most often caused by such
substances as detergents, gasoline, oil, and phenolic com-
pounds . Phosphate contained in detergents and chemical
fertilizers may constitute a hazard if present in excessive
concentrations in ground water. Gasoline and other hydro-
carbons often end up as ground-water contaminants because of
leaking tanks, pipeline breaks, or spills at the land sur-
face. The presence of minute concentrations of hydrocarbons
may result in abandonment of wells because of objectionable
odors and tastes. Frequently, chemical additives complicate
the contamination pattern. Phenols present in oil refinery
or chemical plant wastes are often found in ground waters.
The presence of this contaminant is generally recognized by
its taste and odor, which can typically be detected at con-
centrations as low as 0.001 mg/1 (the U. S. Public Health
Service recommended limit for phenol in drinking water).
230
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Health Hazards
The types of health problems associated with contaminated
water are numerous. The more common health hazards attrib-
uted to contaminated ground water are shown in Table 21.
The results of a national inventory of waterborne disease
outbreaks related to ground-water sources for the period
1946-1970 are shown in Table 22. Contamination at the land
surface and overflow or seepage of sewage into improperly
constructed wells are the major causes of outbreaks of
disease.
Control and Removal of Contaminants
Because of the generally slow rate of movement of ground wa-
ter, a pollutant may exist for years before the problem is
discovered. Contaminating fluids of different densities do
not always move with the main body of ground water. They
can float near the top of the saturated sediments or sink
toward the bottom of the aquifer. Thus, determination of
the direction of flow and areal extent of a contaminated
ground-water body can be complex, and can be accomplished
only by a rather detailed and costly investigation.
Generally, the most common approach to dealing with contam-
inated ground water is to eliminate the source of pollution
as quickly as possible, which is not often feasible. Even
if the source of pollution can be removed, the ground-water
contamination problem still may not be eliminated because a
polluted ground-water body normally moves and disperses
slowly.
The degree of reduction in concentration of contaminants
with time is related to such factors as the hydraulic prop-
erties of the aquifer and recharge conditions. Nevertheless,
long after a source of pollution has been removed, it is not
uncommon for the contaminated ground-water body to continue
expanding in areal extent for many years and travel signifi-
cant distances before its hazardous effect is minimized.
Few studies have been conducted to define the degree to
which contaminants will attenuate with time and distance
from the source. Some recent modeling investigations simu-
lating variation of ground-water quality with time and dis-
tance are expected to assist in the prediction of contami-
nant movement. 8,9)
Other approaches to the solution of ground-water contamina-
tion problems are containment or removal of the pollutant.
Containment involves limiting the spread of the pollutant
within an affected aquifer. Pumping from wells, installation
231
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Table 21. HEALTH HAZARDS ATTRIBUTABLE TO GROUND-WATER CONTAM-
INATION 6)
to
u>
to
Health Hazards
Infant Methemoglobinemia
Fluorosis
Potential carcinogenic effects
Serious illness or death
Nature of Contaminant
Nitrates usually greater than 45 mg/l
Fluorides usually greater than 1.5 mg/l
Selenium-concentration unknown
Arsenic, cadmium, or lead, usually
greater than .05 mg/l
Infectious Hepatitis
Enteric viruses
-------
Table 22. INCIDENCE OF WATERBORNE DISEASE IN THE U.S., 1946-70 DUE TO SOURCE
CONTAMINATION: GROUND WATER (UNTREATED) n
Private
Public
All Systems
Cause Outbreaks
Improper construction or location
of well or spring
Surface contamination nearby
Overflow or seepage of sewage
Seepage from abandoned well
K> Source of contamination not
LO determined
Flooding
Contamination through creviced
limestone or fissured rock
Chemical or pesticide contamination
Data insufficient to classify
Total:
21
49
1
8
4
10
4
46
143
Cases
640
2,779
50
235
66
555
17
2,001
6,343
Outbreaks Cases
1
4
-
1
3
1
-
3
13
2,500
531
-
400
4,400
70
-
16,350
24,251
Outbreaks Cases
22
53
1
9
7
11
4
49
156
3,140
3,310
50
635
4,466
625
17
18,351
30,594
-------
of drains, excavation of affected soils, and artificial re-
charging are the most common methods used for containment or
removal.
Monitoring Ground-Water Quality
Another a,spect of ground-water contamination is the problem
of monitoring chemical and biological quality. Several fac-
tors are responsible for this difficulty, including:
1. The complex nature of aquifer systems and ground-water
movement.
2. The variety of potential contamination sources.
3. The frequent lack of baseline data.
4. The economics of establishing a monitoring system.
The complexity of hydrogeologic conditions was indicated in
previous paragraphs. In most cases it is necessary to de-
fine the extent, thickness, and direction and rate of move-
ment of the polluted body of ground water. This requires
test wells and often geophysical surveys. The ground-water
quality at various depths below the surface must also be
studied. Chemical tracers may have to be introduced into
the aquifer to study direction and rate of flow of the
ground water. Many wastes are of complex chemical composi-
tion, and combinations of different wastes may produce re-
actions necessitating extensive laboratory work and research
to establish the source of pollution.
A significant problem in monitoring ground-water quality is
the general lack of baseline data. Usually, no thought is
given to a monitoring program until such time as a problem
is detected, often too late to establish a meaningful pro-
gram. Even where water quality baseline data are available,
the information is of limited value because many key con-
stituents were not routinely analyzed for in the past. This
applies to most of the trace elements such as selenium,
molybdenum, and cadmium, and such other toxic metals as lead
and zinc.
Finally, the problem of economics influences the establish-
ment of a monitoring program. Federal, state, and often
county legislation have pointed to the need for increased
surveillance of waste discharge movement. Yet, because of
limited funds and personnel, a hazard must be quite severe
before a polluter, enforcing agency, or water user assumes
the economic burden of establishing a monitoring system.
234
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Certainly the majority of small municipal water-supply com-
panies lack both financing and personnel to routinely estab-
lish monitoring programs. Also, most state agencies do not
have adequate financial resources or sufficient trained per-
sonnel to enforce rigid procedures.
In the following sections, sources of ground-water contamina-
tion are discussed in greater detail. Selected case histo-
ries on ground-water quality degradation are included to
provide a better understanding of the nature of the problems
in the Northwest. Locations and references are provided for
each of the cases included except where litigation may be
pending or where information was provided on a confidential
basis.
SEPTIC SYSTEMS
Incidents of ground-water contamination as a result of im-
proper functioning of septic-tank systems are reported in
all six states. Contamination can occur under conditions of
low permeability of the geologic formation, thin soil cover,
high water table, poor well construction, and under-designed
waste disposal systems. Table 23 presents an estimate of
the population in the Northwest served by septic tanks in
1968. As may be seen, almost three million people, or
roughly one third of the entire population in the Northwest,
depend on septic tanks for domestic waste disposal.
Perhaps the greatest occurrence of septic tank problems is
west of the Cascade Range throughout Washington and Oregon.
This is attributed to high annual precipitation, high water
tables, and a high population density. Areas where inci-
dents of ground-water contamination are becoming more numer-
ous are along the Front Range of Colorado, and in the expand-
ing suburbs of major cities in Idaho, Wyoming, and Montana.
In most instances of contamination from this source, local
health departments are aware of the problem and are taking
appropriate control measures.
All states and most counties have regulations governing de-
sign and installation of septic tanks. Typical requirements
are: permit for installation of septic system, minimum lot
size, percolation tests and licensing of contractors. H)
Figure 38 is a diagram of a typical septic tank and soil ab-
sorption system. The complete septic tank and tile field
system consists of three basic components. The first is the
septic tank itself, which is a buried, watertight receptacle
designed to remove solids by settlement and to trap and
store scum and sludge. The second is the distribution box,
235
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Table 23. ESTIMATED POPULATION SERVED BY SEPTIC TANKS IN 1968.
State Estimated population served Percent of total population
Colorado 84,436 a) 4
Idaho 336,130 49
Montana 249,220 37
Oregon 850,708 43
Washington 1,313,410 42
Wyoming 58,195 19
2,892,099
a) As of 1970; estimate supplied by Colorado Department of Public Health.
236
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PRODUCTION
DISPOSAL
EVAPOTRANSPIRATION
Figure 38. Disposal of household wastes through a conventional septic tank and
soil absorption system. '^'
237
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which is needed to insure equal distribution of effluent to
the several lateral lines of the tile field. The third com-
ponent is the soil-absorption system or. tile field. This
consists of a series of pipes, usually made of perforated
orangeburg fiber or plastic material, for the purpose of
distributing the sewage effluent over an area of soil large
enough to absorb it. The distribution lines are normally
laid in trenches which are then backfilled with filter mate-
rial consisting of washed gravel, crushed stone, or slag.
Another similar device commonly used is the dry well or cess-
pool. This is a large buried chamber with walls of a porous
material such as precast, perforated concrete rings or con-
crete blocks. The size of the chamber varies according to
hydraulic loading and other design considerations.
As much as 300 mg/1 of total dissolved solids may be added
to water by domestic sewage. 12) The effluent from septic
tanks can thus increase the concentration of minerals in
ground water. Table 24 shows the range of mineral pickup in
domestic sewage. Under conditions of normal soil pH, effi-
cient removal of phosphates can take place. Chlorides, ni-
trates, sulfates, and bicarbonates are not removed and can
enter into and move freely within an aquifer. Bacteria and
viruses are normally adsorbed onto the soil, but under cer-
tain conditions they can reach the water table and can
travel significant distances. Some other pollutants asso-
ciated with septic tanks include synthetic detergents, ex-
cessive chlorides from water-softener regeneration, and a
number of toxic and non-toxic constituents in special cases
where industrial wastes have been discharged to a septic
system.
One of the first efforts to use hydrogeologic criteria in
land-use planning and in selection of septic tank locations
has recently been made by the U. S. Geological Survey. In
Whatcom County, Washington, a percolation rate map was pre-
pared based on the physical characteristics of geologic
units and the results of percolation tests. 14) Geologic
units with rates slower than permeable limits established by
the county were separated from those with more rapid rates,
thus indicating areas where soil conditions could cause
serious problems and even failure in septic tank filter
fields.
The principal pollutants found in ground water from septic
tank use are nitrates and bacteria. Nitrate as N, in con-
centrations ranging from 10 to 250 mg/1 are believed to
cause methemoglobinemia and even death in infants. 6) More
recent studies, however, cast some doubt as to whether there
238
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Table 24, NORMAL RANGE OF MINERAL PICKUP IN DOMESTIC SEWAGE.
Mineral Mineral range (mg/l)
Dissolved solids 100 -300
Boron (B) 0.1 - 0.4
Sodium (Na) 40 - 70
Potassium (K) 7-15
Magnesium (Mg) 3-6
Calcium (Ca) 6 - 16
Total Nitrogen (N) 20 - 40
Phosphate (PO^ 20 - 40
Sulfate (SO4) 15 - 30
Chloride (Cl) 20 - 50
Alkalinity (as CaCO3) 100 -150
13)
239
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is significant correlation between nitrate in water and
methemoglobinemia irregularities. 15,16)
It is known that bacteria do not travel very great distances
when discharged into fine-grained soils of sufficient thick-
ness to filter them out (see Table 25). Observed distances
traveled are generally less than 30 m (100 ft).
In fractured rock the situation is different. Bacteria can
move significant distances through fractured crystalline_
rock. Studies in mountain regions of the project areas indi-
cate that even with moderate percolation rates and large dis-
tances between water wells and conventional waste disposal
units, septic tanks pose a threat to ground-water quality.
Principal findings of one study carried out in the foothills
of the Rocky Mountains are as follows: 18)
1. Bedrock fractures readily accept and convey contam-
inated percolating waters to shallow ground-water supplies.
2. The direction and rate of movement of bacteria-
laden effluent is largely affected by the character and di-
rection of the bedrock fracture patterns.
3. Insufficient microbial filtration of leach-field
effluent occurs in or along fractures and joints in crystal-
line rocks.
4. The horizontal distances traversed by percolating
effluent through fractured bedrock often exceed 30 m (100 ft),
and may exceed several hundred feet.
As most mountain communities and homesites in the Northwest
rely on individual wells or springs for their water supply
and on individual septic systems for domestic waste disposal,
contamination of ground water is a distinct possibility.
This is particularly true in upland regions underlain by
crystalline rock. A cross section of a typical mountain set-
ting for domestic wells and septic systems depicting possi-
ble movement of contaminants is shown on Figure 39. All too
frequently, the commonly held belief that a water supply is
safe if a leach field is downslope, does not hold true.
What is overlooked is that the bottom of the well may be at
the same elevation as the leach field, and that pumping a
well may change the direction of ground-water movement in
the area.
Case Histories
As stated earlier, septic-tank effluent contamination fre-
240
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Table 25. MOVEMENT OF BACTERIA THROUGH POROUS MEDIA. 17)
Source of pollution
Sewage polluted trenches
intersecting ground water
Sewage in bored latrines
intersecting ground water
Sewage in bored latrines
lined with fine soil
Pollution indicator
Coliform bacteria
Anaerobic bacteria
Coliform bacteria
Coliform bacteria
Observed distance
travelled
Meters
20
15
3
Feet
65
50
10
10
Sewage polluted ground
water
Bacteria
A few meters
241
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INFILTRATION OF RAIN WATER DOWNWARD ALONG
FRACTURES TO THE WATER TABLE
INFILTRATION OF POLLUTANTS FROM LEACH FIELD
. THIN RESIDUAL SOIL DEPOSIT
BEING USED TO DISSIPATE
LEACH FIELD EFFLUENT (DASHED)
NJ
AQUIFER
INTENSELY FRACTURED
NEAR-SURFACE ROCKS
LEACH FIELD
THIN TRANSPORTED SOILS
THICK TRANSPORTED
SOILS, VALLEY FILL
SMALL DRAWDOWN
CONE AROUND WELL
MOVEMENT OF
CONTAMINANTS
TO A WELL
ARGE DRAWDOWN CONE
POSSIBLE TO WELL PUMPING
IN VALLEY
LARGE SPACING OF
FRACTURES AT DEPTH Vjk
Contaminated ground water
Figure 39. A cross-section of a typical mountain setting for domestic wells and septic systems on thin soils
and a fractured rock aquifer. '9)
-------
quently occurs in areas with relatively thin soil cover.
These conditions are found along the Front Range of Colorado,
and in most mountainous areas of the Northwest.
A quantitative study of mountain homesites in the Red Feather
Lakes area of north-central Colorado was made in which geo-
logic, topographic, and hydrologic variables were considered
in order to determine conditions likely to cause pollution
of ground water. 20) Of a total of 85 mountain homesites
with individual wells, 62 percent of the wells were found to
be contaminated by coliform bacteria. The position of wells
in this area relative to bedrock fracture orientations and
leach fields accounted for the high incidence of pollution.
The study confirmed that orientation of joints in the bed-
rock significantly affects the travel paths of contaminants,
and that detailed studies of geologic structure can be used
to evaluate the pollution potential at a site.
Ground-water contamination from septic tank effluent in ur-
ban or suburban areas is reported in all six states. High
bacteria counts and high nitrates in wells serving a commu-
nity of 200 residents in Colorado were traced to shallow and
improperly constructed wells that were located in close
proximity to watercourses. 21)
Septic tank effluent has contributed significant amounts of
ABS (alkyl benzene sulfonate - a detergent) to water-table
aquifers in the South Platte River basin in Colorado. 22,23)
Although ABS itself is not considered to be toxic, its taste
and foaming appearance are regarded as problems and do af-
fect the ultimate usefulness of the aquifer. ABS in ground
water points to the possible presence of other harmful con-
taminants from liquid wastes. Areas thus affected were the
suburbs east of the city of Boulder and in or near the towns
of Wellington, Nunn, Pierce, Eaton, Severance, Hereford, and
Merino. ABS was also detected in water from domestic wells
near the city of Estes Park, located in the Front Range
mountains. In the Denver area, ABS derived from septic tank
effluents was observed in shallow domestic wells in the sub-
urban areas of Adams City, Derby, and Irondale, and in the
rural area bounded by Brighton, Barr Lake, and Henderson.
In Idaho, some ground-water contamination from septic tanks
has occurred in the shallow aquifer near Boise. Fortunately,
this aquifer is not used for drinking water supplies. 24)
Problems are also reported from several other communities.
25,26)
In Montana, some problems with septic tank effluent and well
water have been reported in the Kalispell and Helena areas.
243
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Coliform bacteria and high nitrates have been reported in
water from wells in the town of Livingston located along the
Yellowstone River. 27) Out of 17 county sanitarians con-
tacted during this investigation, 13 reported problems of
septic effluent in their respective counties, and two others
expressed concern about potential contamination and cited
the need for additional investigation. 28)
One community in Lincoln County with a population of about
2,000 has had some severe problems. The town is on a flood-
plain and nearly every dwelling is served by its own well
and septic system. Each spring, with rising water-table con-
ditions, an increase in coliform bacteria is noted in water
wells, indicating fecal pollution. In the period 1962-63,
150 hepatitis cases were reported in this community. 29)
In Oregon, high nitrates resulting from septic tank efflu-
ent are present in the unconsolidated aquifer in the Eugene
area. Nitrate concentrations in ground water range up to
100 mg/1 in this and several other areas of the state. 30,31,
32)
In Washington, suburban developments in several areas have
experienced contamination of ground water from septic tank
fluids. 33,34) Problems have been reported in the Nooksack
Valley in Whatcom County and the town of Snohomish. In the
latter community, of 100 domestic wells, 50 are contaminated.
Many unsewered housing developments in the Tacoma-Seattle
area are built adjacent to lakes, and ground water mixed
with septic effluent discharges into these bodies of water
and causes pollution (e.g., Lakes Steilacoon, Washington,
and Sammamish). Many lakes have to be periodically cleaned
and flushed to allow swimming.
A new shoreline management law enacted in the state of Wash-
ington in 1972 requires buffer zones along lakes and shore-
lines. Development within such buffer zones must be ap-
proved by local or county agencies. Although some benefit
may be derived from such zones it is doubtful that, over the
long term, buffer zones will be effective in controlling
discharge of contaminated ground water to these lakes.
In the Vancouver metropolitan area (Clark County), several
hundred homes have septic tanks and rely on shallow individ-
ual wells for water supply. Several problems of contamina-
tion are reported. 34) This situation is watched very care-
fully, as the Vancouver well field is directly downgradient
from these housing developments.
Urban expansion and reliance on individual wells and septic
244
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tanks is causing concern for ground-water contamination in
the West Valley area of Yakima County. During the summer
months, ground-water levels in the valley rise to a point
where proper treatment of sewage cannot take place in the
unsaturated zone. Samples of 100 private wells indicated
bacterial contamination in 23 wells. 35) in Wyoming, local
problems of ground-water contamination from septic tanks are
reported in the Cheyenne area and in several communities in
the Bighorn Basin. 36)
SEWAGE TREATMENT PLANT DISCHARGE
As of 1968, 875 sewage treatment plants served 6.4 million
people or two-thirds of the total population in the six
states (Table 26). In the arid zone of the Northwest, dis-
charge of effluent from sewage treatment plants presents a
potential hazard to ground-water quality. Treated effluent
is discharged directly to rivers or streams, or else it is
put into lagoons or basins. Discharge of effluent to ground
water from leaking lagoons is discussed in greater detail in
the section "surface impoundments".
In the Plains, most unconsolidated aquifers are in direct
hydraulic connection with the rivers, and pumpage from wells
in the valleys induces surface water to enter the aquifer.
During high flow periods, sewage effluent discharged to
rivers is diluted, but during the rest of the year stream
flow is almost entirely base flow and dilution of wastes is
minimal except in major rivers. It is at this time that ir-
rigation water requirements are at their peak, and ground-
water pumpage is at a maximum.
The effluent discharged by sewage treatment plants contains
chemicals and minerals that cannot be removed by normal sew-
age treatment processes. Furthermore, overloading of treat-
ment plants or poor maintenance can result in the discharge
of only partially treated sewage to surface-water bodies.
Case Histories
Widespread ground-water contamination due to discharge from
sewage treatment plants has occurred in the Denver area. 22,
23) in 1965, a total of 23 plants discharged about 400,000
cu m/d (105 mgd) in the South Platte River basin. In 1974,
530,000 cu m (140 million gallons) of sewage effluent was
discharged daily, 40 percent in excess of plant capacity. 38)
Studies made in 1965 and 1967 indicated that sewage plant
effluent contributed ABS detergents and nitrates to the val-
ley-fill aquifer, mainly between Denver and Kersey. The
valley-fill aquifer is the principal source of water for the
245
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Table 26. NUMBER OF SEWAGE TREATMENT PLANTS AND POPULATION
SERVED IN 1968. 37)
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Total:
Number of Plants
204
93
125
167
208
78
875
Population Served
2,413,203
348,880
436,180
1,102,642
1,798,525
255,050
6,354,480
246
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majority of the public water systems. Numerous individual
and 13 municipal wells reported the presence of ABS in water.
Although ABS-type detergents are no longer manufactured, ABS
pollution of ground water is expected to persist for several
decades. Amounts of nitrate contributed to the aquifer from
sewage-laden waters diverted for irrigation use were be-
lieved to be very significant.
Serious pollution problems in shallow valley-fill aquifers
as a result of insufficient dilution of sewage effluent are
also reported in the Tualatin Valley in Oregon. Stream flow
decreases from 566 cu m/s (20,000 cfs) in winter to almost
zero in the summer time. 39)
IRRIGATION RETURN FLOW
Large land areas totaling 6.3 million ha (15.5 million acres)
are under irrigation within the project area. The distribu-
tion of irrigated areas in the six states is shown on Figure
40. Approximately half of this irrigated land is in the
states of Colorado and Idaho (see Table 27). Principal cen-
ters of irrigation are the San Luis Valley, the Platte and
Arkansas River valleys, the High Plains of Colorado, the
Snake River Plain and the Columbia Plateau. Practically all
(90 percent) of the water used for irrigation comes from
rivers and streams. Total ground-water use for irrigation
is about 20,000 cu m/d (5,200 mgd), most of which is pumped
in Colorado and Idaho.
Contamination of ground water often stems from return flow,
which is irrigation water that finds its way back into the
aquifer and includes by-pass water, seepage, deep percola-
tion, and tail-water runoff. Irrigation water contains vari-
able quantities of dissolved salts, and these dissolved con-
stituents may undergo great changes in concentration and
composition as a result of irrigation operations. Plants
take water from the soil and transpire it to the atmosphere
but take up very little salt from irrigation water. The net
result of evapotranspiration is to remove a large part of
the soil water leaving the salts behind in the root zone.
In irrigated areas where inadequate leaching and drainage
occur, the soil may become saline and unproductive. Excess
irrigation water often leaches salts from the root zone into
the shallow aquifer and frequently this saline ground water
then rises into the root zone. Successful irrigation in
such areas hinges on the proper drainage and removal of sa-
line water to a receiving stream.
Studies by Law and others in Oklahoma showed that drainage
waters from irrigated areas adversely affected both surface-
247
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NORTH
200
'"TT"
400 KM.
I
_J
100 200 Ml.
• REPRESENTS 20,000 ACRES (8,100 HA.
UNDER IRRIGATION
Figure 40. Distribution of irrigated areas in the Northwest.
40)
-------
Table 27. IRRIGATED LAND AREAS IN 1970.
State
Total
Irrigated land
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Hectares
1,862,000
1,497,000
890,000
768, 000
566,000
687, 000
Acres
4,600,000
3, 700, 000
2,200,000
1,900,000
1,400,000
1,700,000
6,270,000
15,500,000
249
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and ground-water resources. Compared with the quality of
irrigation water applied, surface-water return flow showed
an increase of about 20 percent in total dissolved solids
content, and percolating soil water showed a five to eight-
fold increase over the salinity of the applied water. 42)
The status and extent of saline areas in the six states as
of 1960 is shown in Table 28. At that time about 840,000 ha
(2 million acres) were affected by salinity- Almost 50 per-
cent of the saline land was in Colorado.
Case Histories
Degradation of surface water due to irrigation returns has
been studied by Eldridge, who reported on the Yakima River
and the Sunnyside Irrigation District in Washington, the
Boise River in Idaho, and the upper Colorado, Arkansas and
Upper Columbia River basins. 44^ Other salinity studies
have been carried out in the Grand Valley and the South
Platte River basin in Colorado and in Rosebud County in Mon-
tana. 45,46,47)
In the Grand Valley of western Colorado, irrigation is con-
tributing large salt loads to the Colorado River. Seepage
and deep percolation losses to the saline soils and aquifers
and the eventual return of these saline flows to the river
system make the Grand Valley a significant source of salin-
ity in the Upper Colorado River basin. It is estimated that
return flows in the valley are responsible for 37 percent of
the total salt load in the basin. 43)
Pickup of salts results from percolating water coming in con-
tact with the naturally saline soils and aquifers overlying
the Mancos Shale bedrock. The shale, which is also the ori-
gin of many of the soils, contains lenses of salt that are
readily dissolved. Irrigation canal seepage and excess ir-
rigation water move downward to the water table and travel
to the Colorado River (see Figure 41).
Salt budget studies by Skogerboe indicated that each hectare
under irrigation contributes about 27 metric tons of salt to
the valley-wide salt pickup. A projection of this figure
over the entire valley, assuming 28,000 ha of irrigated land,
indicates an annual salt discharge to the Colorado River of
700,000 to 800,000 metric tons. 43) Numerous years of re-
search in the valley have been conducted in an effort to de-
termine the hydrochemical processes controlling salt-load
pickup. One remedy involves reducing the flow of water into
the ground-water system, which can be accomplished by lining
irrigation canals and improving on-farm water management.
250
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Table 28. LAND AREAS AFFECTED BY SALINITY IN 1960
43)
Total land area
Saline land area
Stafe
Colorado
Idaho
Montana
Oreqon
to
Ul
i i
Washington
Wyoming
Land area reported
Statewide
All but 3 counties
4 areas
Statewide
23 counties and
Columbia Basin
Statewide
Hectares
1,000
1,138
761
503
603
899
510
Acres
1,000
2,812
1,880
1,243
1,490
2,221
1,261
Hectares
1,000
397
102
80
42
108
113
Acres
1,000
982
253
197
103
266
280
Percent
34.9
13.5
15.9
6.9
12.0
22.2
Total:
4,414 10,907 842 2,081
19
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IRRIGATION
CANAL
SURFACE RUNOFF OF
IRRIGATION WATER
NJ
SALTS BEING ADDED TO RIVER
FROM GROUND WATER DISCHARGE
COLORADO RIVER
Figure 41. Cross section of Grand Valley of Colorado illustrating salt pickup from
irrigated lands.
-------
In the heavily irrigated South Platte Valley, increased min-
eralization as a result of irrigation is a common problem.
Studies have shown that the same water is used either as
surface or ground water as many as seven times in the 65-
mile stretch from Denver to Kuner, and mineralization in
ground water often increases in a down-valley or downgradi-
ent direction. 49) An intensive study of water quality and
pollution in the valley was made by the Environmental Pro-
tection Agency in 1971-72. 46) Because of the various
sources of degradation, man-made and natural, it is rather
difficult to ascertain what percentage of contamination
problems is a direct result of irrigation return flow.
In the Arkansas River valley, the salt buildup in water from
the unconsolidated aquifer is approaching concentrations
greater than crop tolerance limits, and use of v/ater from
many wells is restricted more by quality than quantity. The
relationship between irrigation practices and water quality
variations is extremely complex. Figure 42 shows an ideal-
ized block diagram of the stream-aquifer system as it re-
lates to water quality. Model simulation of the stream-
aquifer system and changes in flow and salinity appears to
be a promising water management tool. The first study of
this kind was recently carried out in the Arkansas River
valley between La Junta and the Bent-Otero County line. 8)
In the Yakima region of Washington, approximately 160,000 ha
(400,000 acres) of land were under irrigation in 1971 for
various crops. Water in the Yakima River was found to be
affected by irrigation runoff and discharge of poor quality
ground water. 43)
Another recorded instance of contamination is in the area of
Odessa in Washington. Several shallow domestic wells were
taken out of service as a result of contamination by irriga-
tion return waters. 43) Some domestic wells in Snohomish
County, Washington, yield water high in nitrates, believed
to be a result of infiltration of water from irrigated land.
50) High nitrates encountered in some irrigation wells in
Laramie County, Wyoming, are believed to have been caused by
irrigation return flow. 51) Cattle in Rosebud County, Mon-
tana, refuse to drink the highly mineralized water from
shallow alluvial wells affected by irrigation return flow.
47)
In the Snake River valley, three million acres of land are
presently being irrigated. 43) However, poor quality water
that may be related to intensive irrigation has been noted
in only a few areas. Potential ground-water quality prob-
lems could result if an additional five million acres of
253
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PRECIPITATION
I I I I I
N
Low
EXPLANATION
High
RELATIVE D1SSOLVED-SOLIDS
CONCENTRATION
DIRECTION OF WATER MOVEMENT
Figure 42. Idealized block diagram of part of the Arkansas River Valley illustrating
variable ground-water quality. °/
254
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irrigable land were to be developed. At present, sufficient
dilution takes place in the aquifer to decrease the salinity
to tolerable limits. However, a study made on one tract of
some 80,000 ha (202,000 acres) showed that the concentration
of soluble salts in ground water was more than twice that of
the applied surface water, and the potential for salinity
buildup would be greater in areas where ground water is the
source of applied irrigation water. 52,53)
A study of the quality of irrigation waters and subsurface
drainage in Boise Valley showed that nitrate losses to per-
colating water varies widely with type of crop and fertili-
zation practices. The amounts of nitrate lost to ground
water from sugar beet and onion fields were 2.156 Ib/acre
and 15.188 Ib/acre respectively or roughly 2.5 kg/ha and
17.5 kg/ha. 54)
Excessive concentrations of nitrate in ground water in the
Lower Columbia River basin and in the area of Twin Falls,
Idaho, have been attributed to irrigation return flows. 43)
DRYLAND FARMING
Dryland farming on the northern Great Plains appears to be
the principal cause of extensive saline-seep problems affect-
ing large areas of farm land. According to Marvin R. Miller
of the Montana Bureau of Mines and Geology, the saline-seep
problem stems both from the geology of the region and the
crop-fallow dryland farming system now in use. 55,56) Favor-
able conditions for development of saline seeps exist where
glacial till, an unstratified, heterogeneous mixture of clay,
sand, gravel and boulders deposited during glaciation, is
underlain by a thick, impermeable shale. Excess water mov-
ing through the soil and glacial till builds up on top of
the underlying impermeable shale, forming a "perched" water
table. This excess water gradually moves downslope and
eventually reaches the land surface, where it evaporates,
leaving the dissolved salts behind. The water is strongly
saline because of a large supply of natural soluble salts
contained in the subsoil, glacial till, and shale. A cross
section of a typical saline-seep situation in northern Mon-
tana is shown on Figure 43.
Much of the saline water evaporates before reaching peren-
nial streams, leaving the salts behind to be flushed during
spring runoff. Calculations of salt accumulation made by
U. S. Agricultural Research Service scientists show that
large amounts of salt are deposited in seep areas. Assuming
a salt concentration in seep water of 13,000 mg/1 and 25 mm
(one in) of rainfall on a 4 ha (10 acre) area percolating to
255
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to
Ln
CPi
WEATHERED ZONE IN SHALE (SATURATED)
r
HCOLORADO
•(..DRY" AND VIRTUALLY IMPERMEABLE;!?::
GROUND WATER FLOW
Figure 43. Cross section of a typical saline-seep area in northern Montana,
55)
-------
an impermeable clay zone; and assuming that all this ground
water was channeled into a seep area of 0.4 ha (one acre),
13.4 metric tons (14.7 tons) of salt would remain in the
seep area after the water evaporated. 57)
Chemical analyses of saline-seep water from the Fort Benton
area in Montana are shown on Table 29 - Seep water in this
area commonly contains more than 25,000 mg/1 of total dis-
solved solids. Predominant dissolved constituents in the
ground water are sodium, magnesium, sulfate, and nitrate.
High concentrations of trace metals, namely, aluminum, iron,
manganese, strontium, lead, copper, zinc, nickel, chromium,
molybdenum, selenium, and vanadium were found to be present
in the water.
Saline seeps are becoming a regional problem and are now un-
der investigation by several agencies, including the Montana
Bureau of Mines and Geology, the U. S. Department of Agri-
culture, the Montana Department of Health & Environmental
Services, and the Montana Agricultural Experiment Station.
As of 1971, in Montana alone, over 32,000 ha (80,000 acres)
of cropland had been lost to saline seeps. Since then, an
estimated additional 40,000 to 60,000 ha (100,000 to 150,000
acres) have been affected. The loss in farm income due to
saline seeps is five million dollars per year.
Geological conditions favorable to saline-seep development
are similar over vast areas of Montana (32,400 sq km or
12,500 sq mi), North and South Dakota (118,000 sq km or
45,500 sq mi), and the prairie provinces of Canada (181,000
sq km or 70,000 sq mi). Saline seeps are also spreading
over an area of 11,700 sq km (4,500 sq mi) in Montana, un-
derlain by siltstone, sandstone, shale, and coal of the Fort
Union Formation. Dryland farming regions and the area of
potential saline-seep development in Montana are shown on
Figure 44.
Interestingly, the saline-seep problem appears to be a di-
rect result of man's farming activities. Prior to settle-
ment, the natural vegetation on the Plains consisted of buf-
falo grass which consumed relatively large quantities of
water and left no surplus for deep percolation. Present
crop-fallow farming practices, good weed control, stubble-
mulching, and wind barriers have reduced evapotranspiration
losses and more water moves down below the root system.
Field investigations involving drilling of test holes to
monitor ground-water levels and water quality indicate that
cropping of susceptible areas more frequently and permitting
less land to go idle during the summer will reduce the
257
-------
Table 29. CHEMICAL ANALYSES OF SALINE SEEP WATER FROM
THE FORT BENTON AREA, MONTANA. 5b>
(All values are in mg/l, except as indicated)
Parameter Well BF2 Well HA2
Calcium (Ca)
Magnesium (Mg)
Sodium (Na)
Iron (Fe)
Manganese (Mn)
Aluminum (Al)
Lead (Pb)
Copper (Cu)
Zinc (Zn)
Nickel (Ni)
Silver (Ag)
Bicarbonate (HCO3)
Carbonate (CO3)
Sulfate (SO4)
Chloride (Cl)
Nitrate (NOs)
Fluoride (F)
Silica (Si O2)
Specific conductance (micromhos)
PH
31
4,000
6,220
.17
.17
.42
1.15
.13
.22
.55
.08
241
0
29,700
257
630
.9
10.0
34,000
8.29
21
1,270
3,500
.07
.06
.20
.64
.04
.09
.21
.04
248
12
13,435
282
33
0
5.5
18,600
8.49
258
-------
Cn
r////] Cultivated dry lands
Figure 44. Dryland farming and area of potential saline-seep development in Montana. '
-------
chances of development of more seeps and retard the increase
in size of existing ones. Research studies are now aimed at
reducing risks involved in changing crop patterns. It ap-
pears that only a change in farming practices will be effec-
tive in controlling this type of degradation of ground-water
quality.
ABANDONED OIL WELLS AND TEST WELLS
Production of oil and gas is an important economic activity
in the Northwest. Together, the states of Colorado, Montana,
and Wyoming produce about 7 percent of the crude oil in the
nation. Total annual production of crude is some 32 million
cu m (200 million barrels). Crude oil production by state
is shown in Table 30. Wyoming is by far the largest pro-
ducer of oil and accounts for 70 percent of the total produc-
tion of the three states. This oil is produced from several
hundred oil fields located primarily in the Denver Basin of
Colorado, the Laramie, Hanna, Wind River, Green River, Pow-
der River, and Bighorn Basins in Wyoming, and the Powder
River, Williston Basin, and Sweetgrass Arch area of Montana
(Figure 45).
Several thousand exploratory and development wells are
drilled by the oil industry each year, and of these more
than 1,000 unsuccessful wells are plugged and abandoned (see
Table 31). In addition, prior to or during exploration for
petroleum, natural gas, and other mineral deposits, numerous
small-diameter holes are drilled to obtain samples of subsur-
face formations or to serve as shot holes for seismic sur-
veys. In the oil and gas regions of Montana, Wyoming, and
Colorado, thousands of these holes have been drilled. Most
holes range in depth from 3 to 120 m (10 to 400 ft) and aver-
age 60 m (200 ft). Many of these holes intersect one or
several water-bearing formations. Many officials interview-
ed expressed considerable concern about potential ground-
water pollution from interflow conditions between multiple
aquifers as a result of hydraulic head differentials in in-
adequately plugged wells and test holes. Recent legislation
in Colorado, Wyoming, and Montana describes procedures for
abandoning and sealing of wells and test holes, but enforce-
ment is lacking.
Case Histories
Problems of hydrogen sulfide gas and poor quality water leak-
ing into fresh-water aquifers are reported in the Bighorn
Basin of Wyoming. This contamination is due to improperly
constructed oil wells, leaky casing or improper cementing.
The situation is especially bad in the area east and north
260
-------
Table 30. CRUDE OIL PRODUCTION IN THE NORTHWEST. 58'59'60)
Quantity of Crude Oil Produced
State
Colorado
Montana
Wyoming
Year
1971
1971
1972
Cubic meters
4,355,000
5,501,000
22,259,000
Barrels '
27,391,000
34,599,000
140,011,000
1) One barrel is 42 gallons.
261
-------
NORTH
NJ
CTl
I \
\
200
I
400 KM.
100
200 Ml.
1 .
2.
3.
4.
5.
Sweetgrass Arch
Wil listen Basin
Central Montana Uplift
Bighorn Basin
Powder River Basin
OIL FIELDS
GAS FIELDS
6. Wind River Basin
7. Hanna Basin
8. Laramie Basin
9. Green River Basin
10. Denver Basin
Figure 45. Principal oil and gas fields in the Northwesf.
61)
-------
Table 31. OIL AND GAS DRILLING ACTIVITY, 1971-72. 62'63'64)
Exploratory Wells
Colorado (1972)
Montana (1971)
Oregon (1971)
Washington (1971)
2 Wyoming (1971)
Development Wells
Colorado (1972)
Montana (1971)
Oregon (1971)
Washington (1971)
Wyoming (1971)
Oil
Wells
28
4
0
0
33
252
41
0
0
372
Gas
Wells
18
16
0
0
10
119
17
0
0
33
Plugged and Abandoned Total
Wells Wells
325
283
1
0
302
205
66
0
0
143
371
303
1
0
345
576
124
0
0
548
-------
of Worland. 36>
Concern has also been expressed about the practice of pull-
ing old casings in order to reuse them for exploratory drill-
ing. It appears that some operators cannot obtain the neces-
sary steel pipe because of the present steel shortage and
resort to pulling out old well casings without taking proper
steps to seal or plug these holes.
A classic example of problems that can arise from abandoned
wells has occurred in Colorado. 65) in 1915, an oil test
hole was drilled in west-central Colorado to a depth of 560
m (1,837 ft). This well encountered warm, mineralized water.
Fifty-three years later, on May 9, 1968, the well was found
to be discharging 7,338 cu m/d (1,350 gpm) of brackish water
with a concentration of 19,200 mg/1 dissolved solids. It
was estimated that this flow contributed 52,000 metric tons
(57,000 tons) of dissolved solids per year to the White Riv-
er. The well was subsequently plugged, after which the hy-
drostatic pressure built up, causing other non-flowing wells
in the area to flow, and creating saline seeps in the vicin-
ity of these wells.
A study of potential ground-water contamination from geo-
physical boreholes made by the Montana Bureau of Mines and
Geology indicated that ten seismic companies drilled nearly
301,000 seismic holes in Montana in the 1950-1970 period. 66)
It was found that standard practice for plugging seismic
holes is to place a cement, plastic, or natural rock plug
one to 3 m (3 to 10 ft) below the ground surface, whereupon
the hole is filled to the surface with drill cuttings. For
flowing holes, most companies use an inflatable plug, then
backfill with cement or drill cuttings. The investigators
found that seismic holes tend to effectively plug themselves.
Field tests carried out during exploration activities showed
that practically all seismic holes sealed themselves within
a few days after being shot. Although interflow between
aquifers occurred through seismic holes in some situations,
it was believed that seismic programs have had no noticeable
effect on Montana's ground water.
BRINE INJECTION
Salt water is commonly produced together with oil and gas,
and this oil field water can be considered a form of indus-
trial waste.
In the production of oil, oil field brine is injected under
pressure back into the oil reservoir to provide the neces-
sary hydrodynamic drive in secondary recovery operations.
264
-------
In many cases this is a safe and useful way to dispose of
brine.
Oil-producing reservoirs are situated within formations con-
taining saline ground water, so that injection of brine into
them is not of great concern. The potential danger lies in
failure of injection wells, which would cause brine wastes
to flow into fresh-water zones. Once injected, the pressur-
ized saline water is difficult to control. It may be di-
verted to paths of least resistance, known or unknown, nat-
ural or artificial. These escape routes multiply with prox-
imity to the land surface and include such natural geologic
phenomena as fractures and faults, variations in overburden
pressure resulting from topographic relief, and secondary
solution systems. They also include man-made outlets cre-
ated by earlier exploration and production activities — old
bore holes, shot holes, oil and gas wells and abandoned pro-
ducing wells penetrating the reservoir. 67)
The chemical characteristics of brine are also cause for con-
cern. Oil field brines may be several times more saline
than sea water (see Table 32) and highly corrosive to metals.
Steel casings may easily corrode and break, allowing the in-
jected fluid to disperse in the rock zones. Only small
quantities of brine are needed to cause severe degradation
of fresh-water aquifers.
Case Histories
There is practically no documentation regarding ground-water
contamination caused by injection of fluids in spite of the
large quantities of waste water injected in thousands of
wells. In Wyoming, there are 2,264 injection wells and in
Montana, 782. 69,70) AS of 1972, in Colorado, a cumulative
total of 160 billion cu m (one trillion barrels) of fluid
had been injected into various formations. 71) in 1972, 22
million cu m (138 million barrels) of fluid were injected in
Colorado oil fields while only 5 million cu m (32 million
barrels) of oil were produced. Thus, the amount of fluid re-
turned to the formation was more than four times the amount
of oil withdrawn. Injection pressures ranged up to 20,000
newtons/sq m (3,000 psi).
Disposal of oil field waste liquid by oil companies must be
approved by state authorities (e.g., the Oil and Gas Con-
servation Commission in Colorado). In one case, in an oil
field in Logan County, Colorado, an oil company was allowed
to dispose of oil field liquids by reinjecting the waste in
the annulus between the string of production casing and the
Pierre Shale and Niobrara Formation. 71)
265
-------
Table 32. COMPARISON OF DISSOLVED SOLIDS IN SEA WATER AND OIL
FIELD BRINE. 68)
Element
Sodium
Potassium
Lithium
Rubidium
Cesium
Calcium
Magnesium
Strontium
Barium
Chloride
Bromine
Iodine
Sea water, mg/l
10,600
380
0.2
0.12
0.0005
400
1,300
8
0.03
19,000
65
0.05
Oil field brine, mg/l
12,000 to 150,000
30 to 4,000
1 to 50
0.1 to 7
0.01 to 3
1,000 to 120,000
500 to 25,000
5 to 5,000
0 to 1,000
20,000 to 250,000
50 to 5,000
1 to 300
266
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DISPOSAL WELLS
In addition to brine and oil field waste injection wells
used by the oil industry, there are several other types of
disposal wells in the Northwest. A few deep wells have been
drilled to dispose of industrial waste, and an estimated
8,000 wells dispose of domestic and agricultural waste flu-
ids in the states of Oregon and Idaho. The impact of these
disposal practices on ground-water quality depends on vari-
ous factors, including quantity, type, and concentration of
waste fluid injected, the rate of injection, permeability of
the aquifer, composition of the native ground water, and
dilution within the aquifer.
A potential threat to ground-water quality is posed by the
thousands of disposal wells in Idaho and Oregon, most of
which discharge waste waters to the unsaturated zones of
basalt aquifers. A variety of contaminated fluids is dis-
charged into these wells, including agricultural runoff,
domestic and municipal sewage, and storm runoff from urban
areas. The federal government and a few industries use deep
wells to dispose of radioactive and chemical wastes.
Case Histories
A well-documented case of deep well disposal occurred at the
Rocky Mountain Arsenal in Denver. 72,73) This arsenal manu-
factured chemical warfare products and discharged waste flu-
ids to leaky disposal ponds, causing contamination of ground
water and crops. As an alternate disposal method, an injec-
tion well was drilled to a depth of 3,617 m (12,045 ft), and
starting in 1962, waste water was injected into fractured
Precambrian rocks. Injection rates ranged between 12.6 and
19 1/s (200 and 300 gpm). Soon after the start of injection,
tremors and earthquakes took place in the Denver area. A
direct correlation between earthquake and injection fre-
quency was established, injection was stopped, and tests
were made to determine the feasibility of removing the fluid.
74,75)
There is an active deep disposal well operation located near
Cheyenne, Wyoming. Nitrate waste is injected into a sand-
stone bed of the Pierce Formation at a depth of 1,500 m
(5,000 ft). Although no ground-water problems have been re-
ported, local health agencies are concerned about the poten-
tial impact on ground-water quality from this facility. 76)
Disposal wells are also in use at the National Reactor Test-
ing Station (NRTS) in Idaho. One well at the Test Reactor
Area (TRA) is 395 m (1,300 ft) deep and has been used since
267
-------
1969 for disposal of about 570,000 cu m (150 million gallons)
per year of nonradioactive waste water. 77) The injected
fluid contains about 1,200 mg/1 of dissolved solids, which
is approximately five times as much as that of the natural
ground water in the area. In addition, the water discharged
before 1972 also contained one to 2 mg/1 of hexavalent chro-
mium. Estimates are that the bulk of the discharge is to
the Snake Plain aquifer at depths of 150 and 210 m (500 and
700 ft) .
Another disposal well at the Idaho Chemical Processing Plant
on the same NRTS site also discharges fluids directly into
the Snake Plain aquifer. This well is 180 m (600 ft) deep.
Potential contaminants injected are tritium, sodium chloride,
and sulfuric acid. A total of 23,000 curies of radioactiv-
ity, 7,100 metric tons (7,800 tons) of salt, and 730 metric
tons (800 tons) of sulfuric acid have been discharged to
this well since 1952 (see Table 33). The effects of radio-
nuclides on ground-water quality are discussed in the sec-
tion on radioactive waste disposal.
There are an estimated 3,000 disposal wells in Oregon, the
majority of which are used for domestic waste disposal. In
the Portland area, some wells are used to recharge water
utilized for air conditioning. In 1968, a comprehensive in-
vestigation was made of disposal wells in the lava terrane
of central Oregon by Sceva. 77) The disposal wells in this
area are tied into septic tank systems and are generally
drilled to the underlying lava, to a depth where cracks and
crevices can receive and disperse the effluents. A sche-
matic .diagram of a typical sewage disposal well in lava ter-
rane is shown on Figure 46. No major ground-water quality
deterioration was noted during the survey, but little or no
filtration is provided by the lava rock and the threat of
contamination exists. Deep, uncased water wells were found
to be particularly hazardous. Figure 47 illustrates the
mechanism of potential contamination of an uncased water
well by septic effluent discharged into a disposal well. Re-
cent laws passed in Oregon require permits for waste disposal
wells as of January 1, 1975, and prohibit construction or
use of such wells after January 1, 1980. 79)
In Idaho there are some 5,000 disposal or drain wells in the
Snake River Plain. Approximately 3,000 drain wells are con-
centrated in Lincoln, Jerome, and Gooding Counties (see
Table 34). 79) Results of an investigation of the effects
of disposal wells on ground-water quality by the Idaho Bu-
reau of Mines indicate that drain wells are used where geo-
logic conditions at or near the ground surface render con-
ventional disposal systems impractical. In many areas soil
268
-------
Table 33. AVERAGE COMPOSITION OF LIQUID WAST£ EFFLUENT DISCHARGED AT THE
IDAHO CHEMICAL PROCESSING PLANT DISPOSAL WELL. 78)
Waste Product
Tritium (H3)
Strontium-90 (Sr90)
Cesium-137(Cs137)
Zircon! urn -niobium -95
(Zr95-Nb95)
Cerium-144 (Ce]44)
Ruthenium-rubidium- 106
(Rhl06_Ru106)
Total Radioactivity
Sodium chloride
(NaCI)
Sulfuric acid
(H2S04)
Sodium hydroxide
(NaOH)
Dissolved solids
Temperature
Approximate
Average
Annual
Discharge
Half-life 1962-1972
12.3 years 505 Ci
28. 9 years 4 Ci
30 years 4 Ci
65 days 2 Ci
284 days 1 Ci
368 days 1 Ci
520 Ci
390 tons
40 tons
14 tons
Average
Concentration
in Effluent
1962-1972
430 pCi/ml
3 pCi/ml
3 pCi/ml
1.5 pCi/ml
1.5 pCi/ml
1 pCi/ml
440 pCi/ml
160 mg/l Na
245 mg/l CI
45 mg/l SO4
600 mg/l
70° F (21°C)
Approximate
Total
Discharge
Since 1952
22,OOOCi
18 Ci
18 Ci
62 Ci
96 Ci
23 Ci
23,OOOCi
7,800 tons
800 tons
280 tons
269
-------
O
HOUSE
SEPTIC TANK
oc.r i i^ IMNINX
^#:^£#;:i^;-fo:-;?£/#j "i"c r i V M '"• "t:i:'-:-" •'.•:•'; ;:-.'-vil
-SEWAGE WELL
SCUM
MASSIVE BASALT
INTERFLOW ZONE
BASALT
Figure 46. Schematic diagram of a typical sewage disposal well in lava terrane.
79)
-------
SHORT LENGTH OF
WELL CASING
SEPTIC TANK
DISPOSAL WELL
&-&&^
CASCADING
WATER
1 PERCHED
li WATER
TABLE ^
Figure 47. Potential contamination of ground water from perched water
entering uncased water well . '')
271
-------
Table 34. NUMBER OF DRAIN WELLS IN THE SNAKE RIVER PLAIN (By County)
79)
County
Bannock
Bingham
Blaine
Bonneville
Butte
Camas
Cassia
Fremont
Good ing
Jefferson
Jerome
Lincoln
Madison
Minidoka
Power
Twin Falls
*Mostly natural sinks in the lava.
Estimated Total
Approximate Number of
Drain Wells
Less than 10
200
Less than 10
1000
Less than 10
Less than 10
Less than 10
50
1000
50
1000
1000
Less than 10
100
50*
20
5000
272
-------
cover is thin and often impermeable, and septic tanks cannot
function properly. In addition, it was found that many peo-
ple believe that wastes will be rendered harmless by natural
purification in the subsurface.
The numerous openings, fractures, channels, and lava tubes
in the basalt aquifer make it possible to discharge large
volumes of waste fluid without any apparent effects. For
this reason, disposal wells are seldom cased beyond the
first basalt layer and almost never grouted. Most are used
to dispose of septic effluent. The second most common use
is for removing excess irrigation water in areas where topog-
raphic features limit or prevent natural drainage. The
third is to dispose of street runoff where storm sewers are
absent. Such wells are normally drilled on street corners
and near catch basins. A few drain wells are presently em-
ployed to remove industrial wastes. In the past, drain
wells were used to dispose of slaughter and tanning wastes
and wastes produced by fertilizer plants.
Pollution of a public water-supply well by a drain well was
detected in 1960 in the city of Idaho Falls. Fluorescein
dye was injected to trace the contaminant and appeared in
the supply well located 57 m (190 ft) from the drain well in
90 minutes. 79) Bacterial contamination of domestic wells
by waste water discharged into irrigation drain wells was
documented south of Idaho Falls.
In spite of the large volume of waste being discharged to
the Snake Plain aquifer, reported incidents of serious con-
tamination are few. This is attributed to the excellent
permeability of the aquifer and the large underflow of
ground water which dilutes these fluid wastes.
The Idaho Department of Water Resources is currently investi-
gating the effects of disposal-well use on ground-water
quality and updating estimates of the number and types of
active disposal wells. The State has imposed a strict con-
trol program over this practice and relatively few permits
are being approved. 80)
SURFACE IMPOUNDMENTS
Surface impoundments include lagoons, tailing ponds, basins,
and pits used for storing, processing, or treating waste
fluids. Some of these impoundments are designed to hold and
evaporate liquid waste; others are designed to infiltrate
liquid into the soil system. The inflow and outflow of flu-
ids in surface impoundments are rarely metered, and conse-
quently large volumes of a potential contaminant can be
273
-------
leaked to the subsurface before discovery- Some are lined
with layers of cement, asphalt, plastic, or clay.
In mining areas, tailings or waste material are often used
to dam a valley to form a reservoir for waste fluids. These
ponds are commonly of two types: those receiving effluent
from the concentrating process only, and those receiving the
confined effluent from the concentrating process, mine drain-
age, and smelting or refining processes. The prime reason
for such impoundments or tailing ponds is to aid in the re-
moval of suspended solids prior to discharge into streams,
and properly managed, such systems prevent or reduce surface-
water pollution. However, in many cases, impoundments have
been constructed with little thought given to the potential
impact on the ground-water system.
Many unlined ponds are constructed in areas underlain by
highly permeable alluvial material or highly fractured bed-
rock, and are poorly maintained. Leaching of heavy metals
to the subsurface and to the water table frequently takes
place. Lining of ponds with clay or plastic offers only
limited protection against leakage and infiltration because
they are susceptible to punctures, tears, and deterioration.
Clay materials are not impermeable, and large quantities of
polluted waste water can leak through the bottom of an im-
poundment to damage ground-water supplies. For example, a
lagoon 8 ha (20 acres) in size and 3 m (10 ft) deep, lined
with a 60 cm (2 ft) thick clay blanket with a typical perme-
ability of 0.004 cm/d (0.001 gpd/sq ft) can leak about
57,000 cu m (1.5 million gallons) of fluid per year into the
ground-water system. If the rate of ground-water movement
is 15 cm (0.5 ft) per day and the nearest water well is 300
m (1,000 ft), it would take more than five years before the
plume of contaminated water would arrive at the well. In
the meantime, 284,000 cu m (7.5 million gallons) of the
waste water would have leaked into the aquifer.
Unlined basins are used to dispose of treated sewage efflu-
ent at some treatment plants and for storage of liquid raw
materials and waste effluent by industry. The pollutants
from sewage lagoons that contaminate ground water are essen-
tially the same as those from septic systems.
Case Histories
In Colorado, disposal of liquid chemical waste into unlined
holding ponds at the Rocky Mountain Arsenal near Denver
caused pollution of shallow ground water in an area of 30
sq km (12 sq mi) of the South Platte River valley. 81,82,83)
The problem was discovered through damage to crops that were
274
-------
irrigated with water from shallow wells. The contaminated
water moved northwestward in the direction of flow of the
ground water toward the South Platte River (Figure 48).
Contaminants known to be present in the shallow aquifer in-
cluded chloride, fluoride, arsenic, chlorate, the herbicide
2-4D, and the pesticides aldrin and dieldrin. 22) A total
of 119 observation wells was installed and a systematic
study of water quality was undertaken to map the extent of
contamination by measuring chloride concentrations in shal-
low wells. These concentrations reached a maximum of 4,600
mg/1 in several areas. The approximate rate of ground-water
movement was 4 m (13 ft) per day or about 1,500 m (4,800 ft)
per year. Damage claims totaling $74,000 were paid by the
government to five farmers that had suffered crop damage. 83)
Upon discovery of contamination of the shallow aquifer,
waste discharge to leaky ponds was discontinued. The volume
of industrial waste was reduced and a new reservoir lined
with an asphalt membrane was put in operation. In 1961, a
deep disposal well was installed at a cost of $1,419,000,
and waste was discharged to the Precambrian zone. The use
of the well was discontinued and the well was capped in
February 1966 after correlation of disposals with recent
earthquakes in the area was proven. Since that time, wastes
have been discharged to a lined disposal pond.
The water-quality data collected during the 30-year monitor-
ing history at the Rocky Mountain Arsenal was utilized in a
model designed to predict mass transport in the shallow aqui-
fer. 84) The results indicated that the geologic framework
of the area markedly restricted the transport and dispersion
of dissolved chemicals. Dilution from irrigation returns
and seepage from unlined canals proved to be an important
factor in reducing the level of chemical concentrations in
the contaminated ground water.
At the town of Pierce in Colorado, increased mineralization
of ground water caused the abandonment of two municipal
wells. 85) An investigation by the Colorado Division of Wa-
ter Resources indicated that oil field brines had caused the
problem. The town is located in the center of an oil field
where oil has been produced since the early fifties. Saline
water associated with oil production was stored in unlined
pits until 1969. Records show that 75,000 cu m (470,000
barrels) of fluid were unaccounted for in the reinjection
process. It is unclear what the principal source of pollu-
tion has been over the years, but leaky surface impoundments
have probably played a major role. A zone of polluted
ground water about 20 to 30 m (70 to 100 ft) wide was found
to extend through the center of town to the vicinity of the
275
-------
NORTH
BRIGHTON
NEAREST CITY WELL
AREA OF
GROUNDWATER
CONTAMINATION
to
DENVER SEWER
PLANT
ROCKY
MOUNTAIN ARSENAL
MILES
KM
Figure 48. Area of ground-water contamination at Rocky Mountain Arsenal, Denver, Colorado.
82)
-------
municipal wells. Chloride concentrations in the town wells
increased from about 50 mg/1 to 700 mg/1 over a period of
years, and recommendations were made to redrill the water
wells elsewhere.
In Montana, numerous lagoons and tailing ponds are in use by
a copper company in the Anaconda area. Waste water is put
into ponds that together cover an extensive area, and as a
form of treatment, lime is added. Leakage from the ponds
has caused an increase in dissolved calcium sulfate in the
ground water. 27)
A paper mill in the Missoula Valley has experienced problems
from disposal of kraft effluent in settling ponds. Plant
production wells tapping the alluvial deposits close to
these ponds showed increased amounts of dissolved minerals,
and some were abandoned. New wells were drilled away from
the ponds and close to the Clark Fork River. 86) Heavy pump-
age from the plant wells keeps the pollutant from spreading
to adjacent areas.
Waste fluids stored in lagoons at a sugar refinery in east-
ern Montana have infiltrated the soil, entered the underly-
ing ground water, and polluted nearby wells. Beet process-
ing water contaminating ground water is high in BOD and has
a distinct odor. 27)
Complaints of water well owners in the Great Falls, Montana,
area led to an investigation of waste lagoons at a slaughter
house. It was found that lagoon wastes were seeping into
sandstone channels which were in hydraulic connection with
fine-grained, saturated sand deposits. These sands are
widely used by domestic water wells. 27)
In the Coeur d'Alene mining district of Idaho, a study of
ground-water contamination in one valley indicated that wa-
ter in settling ponds was not the source of high heavy metal
concentrations in ground water. 87,88) However, the ponds
acted as a recharge area for the sand and gravel aquifer,
and thus caused the water table to rise. The upper portion
of the aquifer contains old mine tailings with up to 6.0
percent lead and up to 4.4 percent zinc. As the ground wa-
ter rose and saturated these mine tailings, it carried into
solution increased concentrations of the heavy metals.
Seeps and springs emerging on the valley floor downgradient
from the settling ponds had lead concentrations ranging from
0.6 to 1.6 mg/1, cadmium concentrations ranging from 0.20 to
0.40 mg/1, and zinc concentrations ranging from 6 to 37 mg/1.
A diagrammatic cross section of this situation is shown on
Figure 49. Research is being carried out at the University
277
-------
t\J
-J
OO
HEAVY METALS (OLD TAILINGS)-
IN SOIL
NEW WATER TABLE-
OLD WATER TABLE -
•SETTLING POND
SEEPS-
ALLUVIUM
i, u , k<_ , . _—, r-rr-, ,———--r^TTs^TfT^^-^^ ^,^^'''/^^'\>i'^
i-,~,~'-'""^',-^-^'i\'i-^--'-^'.; 'V-^'^^'-C'^'-^^Kv^^V-T^-^v-/^^'^ ^'^^"'-r^y^''^,^
'>^;j^^ ,^v:;7C^/^'^r^^
m$&i&^^
^
'rS-'*^\'^^.^
DIRECTION OF GROUND WATER FLOW
Figure 49. Diagrammatic cross-section of ground-water pollution caused
by settling ponds and mine tailings in northern Idaho.
-------
of Idaho in renovation of waste water and the prevention of
leakage from tailing ponds in the Coeur d'Alene mining dis-
trict. 80,89,90,91)
Prior to November 1968, the mines in the South Fork area of
the Coeur d'Alene River discharged their tailings and liquid
waste directly into the South Fork causing severe surface-
water pollution. Since that time settling ponds have been
built. These ponds have a beneficial effect on surface-
water quality by reducing suspended solids, but their effect
on concentration of soluble metals and the overall impact on
ground-water quality is not yet clear. 88)
Ground-water contamination from sewage lagoons has occurred
at Tieton near Yakima, Washington. Domestic, commercial,
and industrial wastes of the community were discharged to a
lagoon located in a narrow valley underlain by permeable
sands and gravels. Average daily waste flow was 490 cu m
(130,000 gallons), of which 190 cu m (50,000 gallons) were
domestic and the balance industrial waste waters. Within a
few months after discharge to the pond began, a well located
75 m (250 ft) south of the lagoon became contaminated. In-
vestigation showed that coliform bacteria had traveled from
the lagoon to the well. Anionic synthetic detergent had
also entered the aquifer. A tracer study using chloride
showed that sewage infiltrating through the bottom of the
lagoon formed a shallow, elongated mound of fluid resting on
top of the water table. Flow velocities of ground water be-
low the lagoon were in excess of 90 m (300 ft) per day.
About 300 m (1,000 ft) down the valley the velocity decreased
to 60 m (200 ft) per day. Water from the lagoon reached
rural water wells as far as 450 to 600 m (1,500 to 2,000 ft)
down the valley in six days. 92)
Little consideration was given to potential contamination of
ground water when the lagoon was constructed. Infiltration
rates at the lagoon ranged from 7.5 to 38 cm (3 to 15 in)
per day indicating highly permeable soil conditions with
little or no filtration or treatment capability. 92)
On the Kitsap Peninsula near Bangor in the same state, shal-
low ground water has become contaminated as a result of dump-
ing of TNT waste at a U. S. Navy installation. This waste,
resulting from steam cleaning of deactivated ammunition, was
discharged into a catch basin during World War II, and con-
tamination of ground water was only discovered in 1970.
Monitoring wells have been installed and the problem is un-
der investigation by the U. S. Geological Survey and the
Washington Department of Ecology. 93)
279
-------
MINING
The rich mineral deposits in the Northwest have been ex-
plored and developed for over a hundred years. Hundreds of
mines have been developed to obtain precious metals, ores,
and coal. The mining industry is an important segment of
the economy and is expected to undergo rapid growth in con-
nection with the federal government's drive for self-suffi-
ciency in energy. In 1971, the value of minerals produced
in the six states was over half a billion dollars (Table 35).
Major minerals are copper, coal, uranium, zinc, silver, and
lead. Also of economic importance is the production of sand,
gravel, clay, and stone.
Contamination of ground water from mining activities stems
from acid mine drainage and from leaching of mine tailings.
Acid mine drainage results when water and oxygen come in
contact with pyrite or other iron-sulfide bearing minerals
to form sulfuric acid. This acid water is pumped or seeps
from the mine or mineral deposit and is discharged at the
land surface. As shown on Table 36, acid mine drainage and
sediments entering streams and rivers in the Northwest af-
fect fish and wildlife along more than 2,400 km (1,500 mi)
of streams, 1,400 km (880 mi) of which are in Colorado. 95)
Drainage from coal mining activities is considered to be an
important environmental problem. Principal pollutants found
in coal mine drainage are acids, sulfates, iron, and trace
elements. 68) Table 37 shows some of the trace elements
found in coal beds of Montana and Wyoming. 96) Arsenic,
fluorine, mercury, selenium, zinc, and lead are present in
significant concentrations. However, data is not available
as to whether these constituents are significant ground-
water pollutants throughout the mining region.
There were 20 strip mines producing bituminous coal and lig-
nite in the Northwest in 1965. 95) of these, nine were in
Wyoming, seven in Colorado, three in Montana, and one in
Washington. These operations disturbed only a small area of
land (2,200 ha or 5,400 acres) compared to the total land
area disturbed by all types of strip and surface mining oper-
ations (61,400 ha or 151,500 acres). Most of the land was
disturbed by sand and gravel and gold mining operations
(Table 38). These conditions are expected to change drasti-
cally in the future when surface mining of coal on the Great
Plains will begin. In a report on rehabilitation of coal
lands issued by the National Academy of Sciences (NAS), it
is estimated that 360 sq km (140 sq mi) would be disturbed
by surface mining by 1990, and about 780 sq km (300 sq mi)
by the end of the century. 97) Figure 50 shows the areas of
280
-------
Table 35. MAJOR MINERAL PRODUCTION IN THE NORTHWEST EXCLUSIVE
OF PETROLEUM AND RELATED PRODUCTS.
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Mineral
Coal
Sand & Gravel
Zinc
Uranium
Stone
Silver
Lead
Zinc
Sand & Gravel
Stone
Copper
Sand & Gravel
Coal
Silver
Lime
Sand & Gravel
Stone
Lime
Pumice
Gem Stones
Portland Cement
Sand & Gravel
Stone
Lime
Pumice & Volcanic Cinder
Gem Stones
Uranium
Coal
Clays
Sand & Gravel
Stone
Dollar Value 1971
Thousands
33,813
30,155
19,700
15,725
7,933
29,590
18,384
14,515
11,437
6,118
92,125
25,207
12,817
4,248
2,416
28,707
26,708
1,989
1,239
755
26,848
26,069
23,764
1,989
1,239
755
43,311
27,335
17,378
8,750
4,789
281
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Table 36. FISH AND WILDLIFE HABITAT ADVERSELY AFFECTED BY STRIP AND SURFACE MINING IN THE
NORTHWEST AS OF JANUARY 1, 1967. 95)
Streams
Reservoirs and impoundments
Wildlife habitat
to
CO
ro
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
km
1,408
214
218
496
102
16
Length
mi
880
134
136
310
64
10
ha
782
265
95
251
259
81
Surface Number Surface
acre ha acre
1,930 13 243 600
654 -
234 -
620 -
640 -
200 -
ha
8,714
6,666
4,386
5,535
-
acre
21,515
16,460
10,830
13,666
NA
Total: 2,454 1,534 1,733 4,278
13
243
600
25,301 62,471
NA - Not available
-------
Table 37. CONCENTRATIONS OF SELECTED TRACE ELEMENTS IN SOME MONTANA
AND WYOMING COAL BEDS. 96)
(In parts per million/rounded)
Coal, Big Sky Mine
Other coal beds
oo
CO
Arsenic
Fluorine
Mercury
Selenium
Zinc b>
Lead b)
Rosebud a)
1
40
0.06
0.5
2
5
McKay
1
70
0.05
0.4
3
5
Tipple
sample
2
60
0.07
0.5
5
8
Range
1
10
0.02
0.1
2
4
- 5
-60
- 0.2
- 1.5
-54
-30
Average
3
30
0.07
0.5
12
11
a) Weighted average.
b) Recalculated from analyses on coal ash.
-------
M
Table 38. LAND DISTURBED BY STRIP AND SURFACE MINING IN THE NORTHWEST AS OF JANUARY 1, 1965
(in acres). 95)
Coal
(bituminous, Sand
lignite and and Phosphate Iron All
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Total
Acres:
Hectares:
Clay
2,000
500
-
100
500
3,500
6,600
2,700
anthracite)
2,800
-
1,500
-
100
1,000
5,400
2,200
Stone
6,200
700
10
300
1,300
300
8,810
3,600
Gravel
15,500
11,200
13,500
1,300
5,700
200
47,400
19,200
Gold
17,100
21,200
5,600
6,300
400
-
50,600
20,500
Rock
-
3,100
100
-
-
800
4,000
1,600
Ore
25
35
10
10
20
300
400
160
Other
11,400
4,200
6,200
1,400
800
4,300
28,300
11,500
Total
55,025
40,935
26,920
9,410
8,820
10,400
151,510
61,400
-------
«:•••
I\J
CO
Ul
/ ^
\
-•4
/
^>
AREAS OF COAL RESERVES
GENERALIZED LOCATION OF
STRIPPABLE RESERVES
vL t %
-------
coal reserves and the extent of the major strippable coal
areas in the Northwest, and Table 39 lists the strippable
coal resources and recoverable coal. Together, Wyoming and
Montana contain 96 percent of the recoverable strippable_
coal. Most of the strip mining and disturbing of land will
take place in these two states.
Underground gasification of coal as an alternative to mining
is presently under study. Basically, this process involves
hydraulic fracturing of the coal seam to increase permeabil-
ity, after which the coal is ignited. Gasification is main-
tained by injecting air to support combustion through bore
holes. Product gas is then piped to the surface and cleaned
to produce a non-polluting fuel. Potential environmental
problems created by this process are land subsidence and con-
tamination of ground water.
A pilot operation, the Hanna Underground Coal Gasification
Project, is currently underway in Wyoming to investigate the
problems. A large part of this experiment is aimed toward
obtaining baseline data of ground-water quality updip and
downdip from the combustion zone. Chemical analyses show
that the natural coal seam water is of marginal quality with
dissolved solids concentrations ranging from 2,000 to 6,000
mg/1. Trace elements generally exist in low concentrations.
Copper, nickel, chromium, manganese, zinc, cadmium and alu-
minum are present at less than 0.05 mg/1; boron is less
than 0.2 mg/1; iron less than 0.15 mg/1; lead less than
0.1 mg/1; arsenic less than 0.006 mg/1; and mercury less
than 0.002 mg/1. 98) The effects of coal gasification on
ground water have not been studied to any large degree. In
the USSR, an increase in ground-water temperatures of the
surrounding region was noted, which could conceivably in-
crease the soluble salt content of ground water. 99)
More than 9,000 abandoned and inactive underground mines in
the Northwest were tabulated in one national survey (Table
40). About 7,500 of these are metal mines. 95) This figure
appears to be conservative as the Colorado Bureau of Mines
estimates the number of abandoned mines in Colorado alone at
30,000. 100) Drainage from these inactive metal mines may
contain substantial concentrations of dissolved solids and
metallic minerals in addition to being acid.
The mining of oil shale may eventually be undertaken on a
large scale in Colorado and Wyoming. Basins of known oil
shale deposits are shown on Figure 51. The Department of
the interior has leased two 2,000 ha (5,000 acre) tracts in
Colorado to oil companies on the condition that mining be
done conventionally, either by surface or underground tech-
286
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Table 39. STRIPPABLE RESOURCES AND RESERVES OF COAL IN THE NORTHWEST
AS OF JANUARY 1, 1968. 97)
(Thousand Short" Tons)
Remaining
strippable
resource Recoverable
Average Thickness (0-130 feet strippable
(feet) (meters) overburden)0'' resource
COLORADO
Bituminous 12
Subbituminous
Lignite
Total:
WASHINGTON
Bituminous
Subbituminous 22
Lignite
Total:
WYOMING
Bituminous
Subbituminous 67
Lignite
Total:
3.6
870,000
696,000
6.6
500,000
500,000
400,000
400,000
Strippable
reserves
500,000
Total:
MONTANA
Bituminous
Subbituminous
Lignite
28
19
870,000
8.4 7,813,000
5.7 7,058,000
696,000
6,250,000
5,646,000
500,000
3,400,000
3,497,000
14,871,000 11,896,000 6,897,000
135,000
135,000
20.1 22,028,000 17,622,000 13,971,000
22,028,000 17,622,000 13,971,000
a) 0-40 meters overburden
287
-------
Table 40. ABANDONED AND INACTIVE UNDERGROUND MINES IN THE
NORTHWEST AS OF 1966. 95)
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Coal
565
11
334
61
247
26
Metal
1,699
1,749
1,691
1,140
907
295
Non-metal
7
208
146
3
52
_
Total:
1,244
7,481
416
288
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00
(O
NORTH
0
1
1
0
200
1
1
100
400 KM
1
1
200 Ml.
6REEN RIVER
BASIN
WASHAKIE
BASIN
PICEANCE BASIN
Figure 51 . Areas underlain by oil shale. ' ^ '
-------
niques. Various mining methods and energy conversion proc-
esses are now under investigation by private industry and
federal and state agencies. These include strip mining,
vertical shaft, canyon wall mining and underground process-
ing. At the present time, a plant on a 1,600 ha (4,000
acre) site in the Piceance Creek basin of Colorado is pro-
ducing 4 to 5 cu m (25 to 30 barrels) of oil per day by in
situ development. 103) Contamination of ground water may
result from leaching of shale waste piles on the land sur-
face or from in situ development. Estimates are that com-
mercial oil shale operations planned for the Piceance Creek
basin in Colorado could generate as much as 60 million tons
of complex solid wastes annually by 1979- These wastes
would contain not only inorganic trace elements and water-
leachable salts, but also considerable amounts of residual
organic matter containing aromatic hydrocarbons. 104)
Case Histories
An intensive study of the occurrence and production of acid
drainage was carried out in a lead-zinc mine in northern
Idaho. 105) At the time of the investigation, this mine dis-
charged 170 1/s (2,700 gpm) of water containing heavy metals
and with a pH of about 3.3. Flow measurement and water
quality determinations were made at various levels in the
mine and the zinc ore body. Differences in pH values were
found between the older, upper levels and the newer, lower
levels. Low pH water was found in areas of lead-zinc ore
rich in pyrite. Vertical water movement in the mine was
found to be important in the production of acid and the
transportation of heavy metals. The quantity of acid drain-
age varied directly with the amount of surface runoff. The
mine water and ore body water contained 0.03 to 2.8 mg/1
cadmium, 15 to 1,095 mg/1 zinc, 0.38 to 2.3 mg/1 lead, and
3.1 to 838 mg/1 iron. The pH ranged from 2.6 to 6.1.
In Montana, over 100 mines are contributing to the acid
drainage problem. These include lead, copper, and silver
mines in the Dry Fork-Belt Creek area. Tailings from these
mines also pollute the streams.
Seepage from coal mines in the Sand Coolee district of north-
central Montana also causes serious water pollution. This
acid drainage originates as precipitation onto the Kootenai
Formation, a fractured sandstone. The water percolates down-
ward to the coal mines and emerges as acid water. Both tail-
ings and drainage problems have been investigated by the
Montana Department of Health. 27) Coal acid problems are
also present in the Belt Creek area of Montana, where coals
high in pyrite, contribute drainage which is very acidic and
290
-------
high in heavy metals.
There is considerable concern about the impact on ground-
water quality from future coal strip mining in eastern Mon-
tana and Wyoming. Although the coal in Montana is lower in
sulfur content (as pyrite) than eastern coal beds, acid wa-
ter could be produced. Water-bearing sandstones are asso-
ciated with, these coal beds, and excavation of coal may
destroy and dewater aquifers. In Wyoming, the NAS study on
the potential for rehabilitation of strip mined land indi-
cated that future strip mining and dewatering near Gillette
would impair several hundred domestic water wells. It was
also acknowledged that no known method to patch the gaps in
coal-seam aquifers once the coal is removed presently ex-
ists. 97)
Other problems of acid mine drainage are reported in the
Butte area and in the Upper Blackfoot River basin of Montana,
In the Butte area, seepage from the town's sewage system re-
acting with minerals present in the soils causes acid drain-
age to streams.
Drainage from abandoned gold mines is believed to be the
source of high manganese occurring in individual water sup-
plies in Snohomish County, Washington. 106) North of Boise,
Idaho, cases of cattle poisoning were reportedly caused by
arsenic leachates from abandoned mines. 107) A small town
in Jefferson County, Montana, has had problems with ground-
water pollution caused by acid drainage from abandoned or
closed mines. 108)
Old mine tailings deposited during past years when less effi-
cient metallurgical processes were available are a signifi-
cant threat to the water quality of the Coeur d'Alene Basin
in Idaho. Although the hydrology of tailings piles under
local climatic conditions in this river basin is not fully
understood, it is known that ground water discharging
through these tailings leaches the metal sulfides both bio-
chemically and chemically. 90,91) Where the permeability of
the aquifer is sufficiently high, discharging ground water
contributes appreciable amounts of zinc to the surface-water
drainage in the basin. This phenomenon is occurring in the
sediments of Canyon Creek. In the Ninemile Creek area, old
tailings have been deposited on sediments of lower permea-
bility, and although the discharging ground water is notice-
ably high in metal content, the rate of discharge to streams
is much lower. Consequently, the rate of addition of metal-
rich ground water to streams in this area apparently is not
sufficient to cause a significant surface-water quality
problem.
291
-------
A hydrogeologic study was made of a large tailings pile in
northern Idaho covering 28 ha (70 acres) with a height of
7.5 m (25 ft). Tailing material was derived from a lead
sulfide and zinc sulfide mine. A total of 112 piezometers
was installed on and around the pile. Contours on top of
the water table indicated a ground-water mound below the
pile, and preliminary analysis of water-quality data .showed
that transfer of ions (calcium and potassium) was taking
place from the pile to the surrounding ground-water system.
105) Leaching of heavy metals by water passing through mine
tailings was also demonstrated in the Cataldo Mission Flats
area of the Coeur d'Alene River valley. Mean concentrations
of zinc and lead in ground water were 52 mg/1 and 0.8 mg/1
respectively- 89) Ground water for an industrial supply be-
low Kellogg in the same valley contained 0.04 mg/1 of cad-
mium and 25.0 mg/1 of zinc. 109)
In western Colorado, leachate from uranium tailings has en-
tered the rivers. One of the dumps is over 22 ha (54 acres)
in size, and contains 2.3 million metric tons (2.5 million
tons) of tailings. Recent stabilization of these piles ap-
pears to have helped to diminish infiltration and leaching.
110) Similar problems from uranium mining exist in the
Shirley Basin in Wyoming where high Ra 226 has been found in
ground water. Ill) Weathering of piles of potassium dich-
romate at a plant site in Montana caused chromium to enter
the underlying aquifer. Corrective action consisted of re-
moval of the piles and chemical treatment of the soils. It
is believed that the contaminated ground water is moving
slowly toward the Yellowstone River. 27)
Leaching of sulfide-rich tailing piles near Ironton, Colo-
rado, has caused surface-water pollution. The pH of Albany
Gulch, a stream which flows through the waste-rock pile, was
lowered by 3 pH units over a distance of about 50 m (50
yards). 112)
Several studies involving trace metals and ground-water qual-
ity are underway- The effects of molybdenum on the environ-
ment are currently being studied by a team of investigators
in Colorado. 113) The Molybdenum Project Group at the Uni-
versity of Colorado has extensively sampled mining areas and
surface-water drainage systems. Similarly, Colorado River
basin waters have been tested for traces of vanadium asso-
ciated with vanadium and uranium mining operations. In both
cases, no data is available yet pertaining to ground-water
quality. 114) The large trona mining"operations in the
Green River basin of Wyoming are currently being investigated
as possible sources of ground-water contamination. Surface-
water deterioration was responsible for initiating this in-
292
-------
vestigation. 108)
A potentially troublesome ground-water situation was uncov-
ered by a team of U. S. Department of Agriculture research-
ers involved in a program dealing with the reclamation of
lignite strip mine spoil piles in eastern Montana and North
Dakota. At the project site the team found coal seams in-
terlaced with seams of shale in the Fort Union Formation
containing large quantities of nitrogen locked into ammonia.
Approximately 200 kg of exchangeable NH4+ nitrogen per hec-
tare was found to be initially present in each meter of
thickness of these sedimentary rocks. When exposed to air,
water, and bacteria, this nitrogen would oxidize to become
compounds potentially hazardous to ground water, but useful
during the reclaiming of the mine spoil piles. Conclusions
of the study were that strip mining or the irrigation of
thousands of hectares of this shale would greatly enhance
the potential for a dangerous NO3 nitrogen buildup in sur-
face and ground water and that well designed and well exe-
cuted water control practices would be needed. 115)
LANDFILLS
Landfill refers to a land area used for dumping of solid
waste from urban or rural communities and industry. In-
cluded in the waste materials are household and commercial
refuse and waste products generated by factories. Other
terms considered synonymous are refuse dumps and sanitary
landfills. These wastes are dumped on top of the land sur-
face, in excavations, in marshy or swampy areas, or in aban-
doned mines. Practically all dumps are not acceptable from
an environmental point of view because of leachate produc-
tion. Few are engineered or designed to prevent contamina-
tion of ground water and surface waters.
The volume of urban waste produced is in direct proportion
to population, and most major landfills or dumps are thus in
the Denver and foothills areas of Colorado, and in the Port-
land-Vancouver-Tacoma-Seattle region of Oregon and Washing-
ton. Industries are spread over the entire region, and
their refuse dumps are generally remote from urban centers.
Production of leachate depends on the availability of water
moving through the waste material. This water can be pre-
cipitation (rain or snow), moisture in the waste itself, or
ground water or surface water entering the landfill site.
Research studies have shown that 135 mm of water per m (1.62
in of water per ft) of depth of fill is necessary to produce
leachate. 116) in the arid portion of the Northwest, land-
fills are generally not considered a problem as there is
293
-------
little or no leachate production. However, this is not the
case in the moist climate west of the Cascade Range or in
some areas of Idaho where annual precipitation is in excess
of 1,000 mm (40 in) per year.
Case Histories
Urban waste dumped over a period of five years at a site
north of the city of Moscow, Idaho, was found to have con-
taminated ground water. This site, covering 3 ha (7 acres),
was located in a 10-ha (25-acre) basin on.loess and alluvial
material. These deposits were saturated most of the year
due to a high water table. Electrical resistivity surveys
and piezometers were used to map the extent of the contami-
nated ground-water body. 117)
In the Boise, Idaho area, leachate from a landfill located
on a cliff has entered the ground water causing local well
owners to complain. Hydraulic gradients were found to be
very steep, causing the contaminated ground water to move
rapidly. *4)
In Washington, no cases of contamination of water wells from
landfills have been reported, but leachate generation has
been detected at several dumping sites. In one county in
the state, 7 of 15 landfill sites had "serious" leachate
problems. 118) One large landfill operation situated on
glacial drift was found to produce large amounts of leachate
that emerged as springs along the banks of a stream. 119)
In Oregon, ground-water contamination has been detected from
a landfill near Eugene located along a river. A total of 24
wells was installed to monitor the movement of the contami-
nated water. 30) Another landfill under study is located
west of Portland. This landfill, now abandoned, is situated
on volcanic terrane. Leachate from this site has affected
some domestic wells, necessitating the replacement of water
wells. 120)
Industrial dumps have created ground-water quality problems
in some areas. Plywood plants in western Montana, which
formerly burned wood wastes are no longer allowed to do so
because of air pollution regulations. These wastes were
then buried in gullies. Glue extracts in the wastes con-
tained phenols which entered the ground water causing con-
tamination of a water well. 27) Land disposal of wood
wastes is also creating problems in Oregon. Leachates from
sawdust, bark, and chips of bark contain tannic acid, which
discolors the waters and lowers the pH. In the Willamette
Valley, leachate from wet wood wastes dumped into an aban-
294
-------
doned gravel pit near the city of Turner, has contaminated a
number of domestic wells. 121] Some of these wastes were de-
posited below the water table, and there was a rapid dis-
persal of the contaminant. Within a period of five months,
the contaminated plume moved 150 m (500 ft) and quadrupled in
size (Figure 52). In Washington, sulfide liquors from wood
and pulp mills discharged into pits have caused contamination
of municipal water wells in the city of Shelton. 122)
Incompletely processed aluminum ore and mill tailings which
had been treated with sulfuric acid and ammonium hydroxide
were dumped into a sand and gravel pit at Keizer, Oregon,
north of Salem. 123) The pollutant spread into highly perme-
able alluvial deposits used by many families for domestic wa-
ter supply. The contamination was discovered in 1946 after
the complaints of local residents. Analysis showed that the
total dissolved solids concentrations in the water from one
well exceeded 1,000 mg/1, ten times the normal concentration.
To alleviate the problem and prevent further contamination,
the waste was removed from the pit and two high capacity
wells were pumped for several months to remove contaminated
water. A water sampling program was established to monitor
the extent and movement of the contaminated ground water
(Figure 53). In 1947, the contaminated area covered 0.7 sq
km (0.3 sq mi); in 1953 it had spread downgradient and in-
cluded 2.0 sq km (0.75 sq mi). In 1964, the affected area
was 2.6 sq km (one sq mi). The estimated rate of movement
was 1.4 m (4.5 ft) per day or 500 m (1,700 ft) per year. Be-
cause of .the slow rate of dispersion the contaminant will re-
main in the aquifer for many more years.
RADIOACTIVE WASTE
Radioactive waste disposal in the Northwest takes place pri-
marily at the National Reactor Testing Station (NRTS) in
Idaho and at the Hanford Reservation in Washington. Smaller
amounts of solid wastes are disposed of at the Rocky Flats
plant near Denver, Colorado. Most radioactive waste is in
liquid form and is disposed of in ponds and cribs (trenches
filled with gravel) or injected into wells. Solid waste is
buried in isolated areas in special chambers or trenches.
Disposal of radioactive fluids has been closely watched and
monitored by the U. S. Geological Survey for the past 20
years. Numerous test and observation wells have been in-
stalled at disposal sites and ground-water quality is con-
stantly monitored.
National Reactor Testing Station
Several facilities at the NRTS site in Idaho generate and
295
-------
LIGNIN-TANNIN PLUME
s 0.4 mg/l AUGUST 18, 1972
LIGNIN-TANNIN PLUME
JANUARY 3O, 1973
0 1,000 2,000 M
I—r1 r—'
0 25O 500 FT.
« OBSERVATION WELL
Figure 52. Extent of area of contaminated ground water caused by wood waste
I „ L«4-^ B-./-H-I r Ti irr^P" r OfPnon . /
leachate near Turner, Oregon.
296
-------
1947
1953
• — Observation well
• - Disposal pit
-loo Line of equal hardness of water, mg/l
500
1000 M
1000 2000 FT
1964
Figure 53. Extent of area of confaminafed ground water at Keizer, Oregon.
297
-------
discharge low-level radioactive and dilute chemical liquid
wastes to the subsurface by means of seepage ponds or wells.
The two most significant waste-discharge facilities are the
Test Reactor Area (TRA) and the Idaho Chemical Processing
Plant (ICPP). Together these two facilities account for 75
percent of the total volume of liquid waste discharged to the
ground here and include 80 percent of the total chemical
wastes and over 90 percent of the total radioactive waste. 78)
TRA wastes include several types, which discharged through
four different disposal systems. Low-level radioactive
wastes are discharged to three interconnected seepage ponds
excavated in gravelly alluvium of the Lost River floodplain
and allowed to percolate to the water table 137 m (450 ft) be-
low land surface. Nonradioactive corrosive chemical wastes
' are discharged to a separate seepage pond. Nonradioactive
cooling-tower blowdown wastes are directly injected into the
aquifer through a deep well. Sanitary wastes go to another
seepage pond. Discharge to the TRA radioactive-waste ponds
has averaged 760,000 cu m (200 million gallons) per year.
About 70 percent of the low-level radioactive waste dis-
charged to these ponds is short-lived with a half life of a
few days or less. Table 41 lists the average discharge and
concentration of longer-lived nuclides in liquid waste dis-
charged to the ponds. Liquid chemical waste has been dis-
charged to the TRA chemical waste seepage pond since 1962.
About 170,000 cu m (44 million gallons) per year of chemical
waste fluids is discharged to this pond. These wastes, orig-
inating from ion-exchange system regeneration, consist on the
average of 910,000 kg (1,000 tons) per year of sulfuric acid,
450,000 kg (500 tons) per year of sodium hydroxide, and
45,000 kg (50 tons) of sodium chloride.
In addition to disposal ponds, two deep disposal wells are in
use at the site (see previous discussion under Disposal Wells).
At the TRA facility, nonradioactive waste water from cooling-
tower blowdown is injected into a 395-m (1,296-ft) deep dis-
posal well, and at the ICPP, located about 3 km (1.8 mi)
southeast of the TRA site, low-level radioactive waste is
discharged into a 180-m (590-ft) deep well. These wastes are
discharged directly into the Snake River Plain aquifer.
Waste disposal in the TRA ponds has caused the formation of
an extensive perched-water body beneath the ponds. 124) The
water percolates downward through gravel, sand, and silt to a
basalt layer 15 m (50 ft) below the surface. At first, the
water formed shallow perched-water bodies in the alluvium
above the basalt. Later the perched water seeped into the
basalt and formed a second, larger perched-water body.
Further downward movement is retarded by a layer of clay and
298
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Table 41. LONGER-LIVED NUCLIDES BEING DISCHARGED AT THE TEST REACTOR
AREA FACILITY ON THE NATIONAL REACTOR TESTING STATION SITE.
78)
ro
Waste nuclide
Tritium (H3)
Strontium -90 (Sr 90)
Cesium-137 (Cs137)
Cobalt-60 (Co60)
Half-life
(years)
12.3
28.9
30
5.2
Approximate
average discharge
1962 through 1972
(curies per year)
500
5
5
20
Average
concentration
1962 through 1972
(picocuries per ml)
615
6
6
25
Approximate
discharge
since 1952
(curies)
8,300
70
110
400
-------
silt within the basalt about 45 m (150 ft) below the surface
and about 90 m (300 ft) above the regional water table. It
is estimated that the average travel time of waste water from
the ponds to the aquifer is one to 3 years. A cross section
of the disposal pond area showing the perched waste water zone
as of 1961 is shown on Figure 54. The upper perched water
covers an area of about 2.5 ha (6 acres). The perched water
in the basalt covers about 1.3 sq km (0.5 sq mi) and has a
maximum saturated thickness of 30 m (100 ft). The water table
slopes laterally in every direction at a gradient away from
the disposal pond. This perched-water body also contains
seepage from the chemical and sanitary disposal ponds.
Tritium is the only radionuclide discharged to the ponds in
large enough quantities and with sufficient half-life to be
readily detected in the perched waste water. Figure 55 shows
the extent of the perched water in the basalt and the tritium
content in 1966. The amount of tritium discharged to the
ponds from 1952 to 1966 was about 3,730 curies. Allowing for
decay, about 2,730 curies would have remained by the end of
1966. About 20 curies was estimated to be in the perched wa-
ter in the alluvium, 1,000 curies in the perched water in the
basalt, and 100 to 600 curies in the Snake Plain aquifer. The
Snake Plain aquifer receives radioactive waste water from the
perched-water bodies and from the disposal well at the ICPP
facility. Observation wells indicate two tritium plumes in
the aquifer - a small one at the TRA facility and a large one
in the ICPP area. Figure 56 shows the extent of the plumes.
Most of this contamination is caused by discharge of radio-
nuclides to the ICPP disposal well creating a waste plume of
about 40 sq km (15 sq mi).
Nonradioactive hexavalent chromium, added to the cooling water
as a corrosion inhibitor, is also discharged in wastes. From
1952 to 1963, the chromium wastes were discharged to the radio-
active-waste seepage ponds. Since 1963, these wastes have been
discharged to the TRA deep disposal well. Chromium serves as
a good tracer of the TRA waste plume in the aquifer because
the ICPP does not discharge chromium. In November 1966, hexa-
valent chromium concentrations in the Snake Plain aquifer below
the TRA site ranged from less than 0.005 to 0.399 mg/1 and aver-
aged 0.060 mg/1. 125) This plume had moved 6.5 km (2.5 mi)
south of the disposal pond, as mapped in 1970 and shown on Fig-
ure 56. According to J. B. Robertson of the U- S. Geological
Survey, there appears to be no significant reduction of hexa-
valent chromium to lower oxidation states in the aquifer.
Sorption does not appear to have a major effect on chromate
migration.
Numerous studies of the migration and distribution of liquid
waste discharged within the NRTS site have been made. These
300
-------
UJ
o
I-
w
L/J
50
100
150
200
WELL WELL WELL
56 54 58
DISPOSAL POND ° ** ao
PERCH ED /WASTE7WATER//IN
' LU
100 200 METERS
I I
0 300 500 FEET
cc.
UJ
•30 UJ
•45
•60
Figure 54. National Reactor Testing Station, Idaho. Cross section of TRA disposal pond area
showing perched waste water zone.
-------
i ]
. i i.i ,
® © © ®j
ASTE DISPOSAL PONDS
\
NORTH
\
\
• Observation wells
Line of equal tritium content,
in picocuries per milliliter (pCi/ml)
Interval, lOOpCi/ml (1966)
,, ~^_ Approximate edge of perched
' water in basalt
Figure 55. National Reactor Testing Station, Idaho Tritium content in perched waste water
below the Test Reactor Area. 125)
302
-------
NORTH
•50— Equal fnrium concenfrarion in pCi/ml
] CNiomium plume - 1970
I Iririum plume - November 1972
NRTS BOUNDARY
Figure 56. National Reactor Testing Station, Idaho,- Distribution of tritium and chromium in
the Snake River Plain aquifer at the ICPP and TRA facilities. 78' 125)
303
-------
studies have been based on some 45 observation wells located
near or downgradient from discharge areas. Robertson states
that calculations for tritium indicate a nearly even quantity
of 13,000 to 14,000 curies has been maintained since 1961 in
the plume, and the decay rate about equals the long-term dis-
charge rate. Thus, the total amount of tritum in the aquifer
is not increasing, and since 1967, the quantity has decreased
because of lower discharge rates. All tritium concentrations
in the aquifer are well below the recommended guide of 3,000
pCi/1 issued by the U. S. Atomic Energy Commission.
In addition to tritium and chromium, several other elements
occurring in the discharge wastes have been used as tracers
to map ground-water flow. These include chloride, sodium,
Sr90, and Csl37. chloride has been found to be the best
tracer of waste behavior because it is discharged more con-
stantly and in more uniform quantities than any other product.
Also, chloride is relatively free from chemical reaction such
as ion exchange or precipitation. The chloride plume closely
resembles the tritium plume. The Sr90 plume is much smaller
than the tritium and chloride plumes and occupies an area of
about 4 sq km (1.5 sq mi). Csl37 is more affected by sorp-
tion than Sr90 and has never been detected in any aquifer
near either the TRA or the ICPP facility.
In general, longitudinal and lateral dispersion of contami-
nants were found to be greater than expected from the classi-
cal theory of ground-water flow or from laboratory model
studies. Vertical migration was found to be limited to the
upper 75 m (250 ft) of the basalt aquifer due to lower verti-
cal permeabilities. Digital model studies of chloride, tri-
tium, and Sr90 migration made by Robertson appear to be a
valid tool for predicting the travel of liquid waste in the
aquifer. Forecasts for the various plumes show gradual
growth but reduced concentrations as a result of dilution and
dispersion.
The impact of these wastes on the environment surrounding the
NRTS is constantly monitored by the NRTS Health Services
Laboratory and results are published annually. As of 1972,
none of the off-site well-water or surface-water samples con-
tained any gross alpha, gross beta, or tritium activity above
the detection limits of the analyses. 126)
Hanford Reservation
The Hanford Reservation, established in 1943, is the major
disposal site of radioactive industrial wastes in the nation.
A wide variety of radioactive wastes are- generated by reac-
tors and laboratories, and by the chemical processing of re-
304
-------
actor fuels to extract plutonium. Liquid wastes are classed
as low, intermediate, or high level. Low-level wastes con-
tain less than 5 x 10~5 yci/ml of radioactivity; intermedi-
ate-level wastes are between 5 x 10~5 yCi/ml and 100 yCi/ml
of mixed radioactivity.
The most highly radioactive wastes are stored beneath ter-
races in tanks. As of 1969 there were 149 tanks, ranging in
size from 190 to 3,800 cu m (50,000 to 1,000,000 gallons),
buried beneath about 3 m (10 ft) of earth. These wastes con-
tain long-lived radionuclides that will decay to a low-level
of radioactivity in about 600 to 1,000 years. 127) LOW- and
intermediate-level liquid radioactive wastes are discharged
into swamps, cribs, dry wells, and trenches. A typical swamp
of 30 ha (77 acres) in size will accommodate a flow of about
30 million 1/d (8 mgd). From the time of startup until 1967,
300 billion liters (80 billion gallons) of low-level waste
containing 20,000 curies of beta activity have been released
to swamps. 128)
The cribs are used primarily for the disposal of intermediate-
level wastes and low-level wastes that are judged to have a
high potential for contaminating the environment. Early
cribs at Hanford were underground timbered structures filled
with graded gravel. Current cribs consist of long, narrow
trenches about 3 m (10 ft) wide at the bottom, filled with a
few meters of graded gravel and covered by a plastic mem-
brane (Figure 57).
The quality of ground water below the cribs is monitored by
wells. When the long-lived radioactive materials, such as
Sr90, Csl37, or Co60, are detected in ground water in concen-
trations approaching 10 percent of the maximum permissible
concentration for drinking water, the crib is removed from
service. From the time of startup to 1967, 23 billion liters
(6 billion gallons) of intermediate-level waste containing
three million curies of mixed radioactivity have been re-
leased to cribs. Of this three million curies, only 500,000
curies remain within the soil due to continuous depletion by
radioactive decay. 128)
Rock filled cavities or dry wells are similar in design to
cribs, but are smaller in size and are located at relatively
shallow depths. These are used for disposal of small quanti-
ties of low-level and intermediate-level wastes.
Intermediate-level wastes with poor or unknown soil adsorp-
tion characteristics are disposed of in liquid waste trenches
constructed with conventional earth moving equipment. The
trenches are managed in such a way as to prevent disposal of
305
-------
LIQUID LEVEL GAUGE WELL',
.DISTRIBUTOR VENT
U)
o
CT>
UNDISTURBED
SOIL
Figure.57. Hanford Reservation, Washington. Cross-section of a typical crib.
128)
-------
high-level wastes or liquid quantities that will exceed the
adsorption capacity of the soil. Approximately 110 million
liters (29 million gallons) of intermediate-level waste con-
taining 660,000 curies of beta activity had been discharged
to trenches until 1957, when this type of disposal was dis-
continued.
Solid wastes are classified according to handling require-
ments and radiation and are packed in cardboard, steel, wood,
or concrete containers prior to burial. Monitoring wells are
located in the burial area to detect any migration of leach-
ate to the ground water. Underground caissons are used for
wastes that are small in volume but high in activity level.
These consist of concrete vaults into which drums containing
waste are deposited. For large pieces of equipment, tunnels
large enough to accommodate railroad cars are used to contain
contaminated equipment.
The reservation is underlain by the Ringold Formation, a unit
consisting of up to 360 m (1,200 ft) of silt, sand, clay,
gravel, and some volcanic ash. This formation extends down
to basalt bedrock. Glaciofluviatile deposits of sand and
gravel have been deposited in channels eroded in the Ringold
Formation. Ground water occurs under artesian conditions in
the basalt and under water-table conditions in the unconsoli-
dated deposits. The water table beneath the reactor areas
lies at an average depth of 30 m (100 ft) and slopes toward
the Columbia River. 129)
There are over 1,300 wells at the site, 300 of which are used
for routine surveillance of radionuclide migration in the
ground-water flow system. 128) Frequent sampling of wells is
carried out and bi-annual reports are issued indicating the
radiological status of the ground water. The locations of
wells and plant facilities are shown on Figure 58. The
ground-water contamination pattern beneath Hanford can be
divided into three source zones based on the kinds and quan-
tities of waste disposed to the ground at each location. The
principal sources of liquid waste are the "200 Areas" of chem-
ical processing plants in the center of the reservation.
Then follow the six production reactor sites located adjacent
to the Columbia River "100 Areas", and finally the fuel fabri-
cation and laboratory area ("300 Area") in the southeast
corner of the reservation.
Contamination at the "200 Areas" stems mainly from effluent
disposed in cribs, swamps, and trenches. In the "100 Areas",
radioactivity in ground water is due primarily to disposal of
wastes in trenches and cribs, but leaks in reactor effluent
systems have also contributed radioactivity to the ground
307
-------
PRODUCTION
REACTORS
100 AREA
PRODUCTION
REACTORS NORTH
100 AREAS
{
200 EAST ^
126 WELL§ *
200 WEST AREA
I I
106 WELLS
CHEMICAL
PROCESSING SEPARATION
FFTF SITE
5 WELLS
FUEL PREPARATION..
AND LABORATORY
300 AREA
19 WELLSl-i
• —1
0 I 2 3 4 5 Ml
• OBSERVATION WELL
RICHLAND
10 WELLS
Figure 58. Hanford Reservation.- Washington. Location of plant facilities and observation
wells. 130)
308
-------
water. In the "300 Area," disposal of low-level fuel proc-
essing wastes to two ponds has caused radioactive and non-
radioactive contamination of ground water. 131)
Field studies at waste disposal sites have shown that essen-
tially all the long-lived radionuclides adsorbed on the sedi-
ments in the unsaturated zone are retained in the sediment
and are relatively immobile. Radionuclides which do eventu-
ally migrate downward into the ground water, with the excep-
tion of tritium, RulOf), and Tc99 (Technetium-99) , are quickly
dispersed and diffused (and possibly resorbed) in the satu-
rated zone. Radiochemical analyses of ground water show that
within 1,000 m (3,300 ft) of the disposal sites, all nuclides
except those noted cannot be detected using the most sensi-
tive analytical methods. 132)
The radionuclides Rul06 and tritium, as well as the nitrate
ion, are readily transported by the ground water and can be
detected at low concentrations. These substances are there-
fore used to trace the movement of slightly contaminated
ground water away from the major disposal areas. Tritium
concentrations in ground water as of July-December 1972 are
shown on Figure 59. 133) Concentrations are expressed as
percentage of the tritium concentration guide (3,000 pCi/1)
issued by the U. S. Atomic Energy Commission. 134) Several
tritium plumes are shown, with the largest extending more
than 16 km (10 mi) from the disposal sites and covering an
area of about 80 sq km (30 sq mi). Contaminants are moving
with the ground-water flow toward the Columbia River.
Nitrate concentrations in ground water are shown on Figure 60.
Concentrations are expressed as percentages of the U. S. Pub-
lic Health Service drinking water standard of 45 mg/1. Sev-
eral nitrate plumes are shown; the largest plume coincides
with the tritium plume. Nitrate concentrations in the plume
range from 4.5 to 45 mg/1 and are over 45 mg/1 in the immedi-
ate disposal areas. As indicated by the extent of the plumes,
in all probability, some radionuclides from the chemical
processing areas are presently entering the Columbia River.
However, the concentrations of these nuclides are too small
to be routinely measurable in the ground water near the river
or in the river itself, and radiation is deemed negligible by
government scientists. 135)
Mathematical simulation studies are being carried out to pre-
dict the future distribution and movement of radionuclides in
the saturated zone. 9) Also, studies of the deep aquifers
are being made to monitor ground-water quality and assess the
potential for deep-well disposal of highly radioactive waste.
fluids. 136)
309
-------
0 Z 4 6 8 10 KM
Tritium Concentrations
July-December 1972
ZZZ2 0.3- 1% CG
T-TT1 1 10% CG
rrn 10 -100% CG
§•• >100% CG
Y//A Basalt Outcrop Above Water Table
-400——Water Table Contours in Feet Above
Mean Sea Level
Expressed as percent of Tritium
Concentration Guide (3,000 pCi/ml)
Figure 59. Hanford Reservation, Washington. Tritium concentrations
'
in ground water.
310
-------
NORTH
NITRATE CONCENTRATIONS
JULY-DECEMBER 1972
O 10-100% PHS DRINKING WATER
STANDARD
• 100% PHS DRINKING WATER
™ STANDARD
-4OO-
BASALT OUTCROP ABOVE WATER TABLE
WATER TABLE CONTOURS ABOVE
MEAN SEA LEVEL
PHS DRINKING WATER STANDARD
IS 45 mg/1
Figure 60. Hanford Reservation. - Washington. Nitrate concentrations
' . 1
in ground water.
311
-------
Rocky Flats, Colorado
Large amounts of tritium from a waste dump containing radio-
active contaminants at the U. S. Atomic Energy Commission's
Rocky Flats plant near Denver have leached into surface
drainage and have ended up in the reservoir of a municipal
water company. One sample collected by the Colorado Depart-
ment of Health in September 1973 had a concentration of
40,313 pCi/1. Tritium concentrations in the reservoir were
10,000 pCi/1, approximately ten times the normal tritium
background in Colorado. HO) The hydrologic and health as-
pects of this problem are now under investigation by the U. S,
Geological Survey and the Colorado Department of Health, re-
spectively.
Oregon
In Oregon, some radioactive waste was dumped at a disposal
site in Gilliam County. A geological study of the disposal
site was made by an engineering firm, and an investigation of
ground-water quality was presumably undertaken. 31)
SPILLS AND LEAKS
Spills or leaks of liquid waste on or below the land surface
from breaks in pipelines, tank truck accidents, and failure
of gasoline tanks or other storage tanks, can cause degrada-
tion of ground-water quality.
Toxic wastes and hydrocarbons can enter the ground and perco-
late to the water table, then move with the ground water to a
point of discharge, such as a pumping well or a river or
stream. Breaks in underground pipelines or tanks often go
undetected for months or years. Frequently, the only indica-
tion of a leak or loss of fluid comes from comparison of
measured volumes pumped, stored, or extracted. When unex-
plained losses of fluids become apparent, a search for leaks
is generally undertaken. Upon discovery of leaks or spills,
recovery of the lost liquid is rarely feasible.
Case Histories
Spills and leaks of petroleum products during transport and
storage are the most common of all reported incidents. Leaks
of gasoline from storage tanks at service stations were men-
tioned by officials in all states in the Northwest. Pipeline
breaks and truck and railroad tank car accidents also account
for a large number of leaks and spills. In the state of Wash-
ington, 1,400 oil spill complaints were reported in the two-
year period of 1970 to 1972. 122) of these, only eight
312
-------
presented a definite threat to ground-water supplies.
In Wyoming, three small businesses were forced to close be-
cause of gasoline that had entered the basements of their
premises. 137) The gasoline had migrated to the water table
from a leaky storage tank at a nearby service station. To
remove the gasoline and the danger of explosion, a large
area was excavated, and the thousands of gallons of contam-
inated water were removed.
In Colorado, gasoline leaks are recorded on a monthly basis
by the State Oil & Gas Inspection office. 138) During one
month, as much as 140,000 liters (37,000 gallons) from vari-
ous sources leaked into the subsurface. These spills are
being mapped for the purpose of determining high incidence
areas. It appears that certain soil types in some areas are
more corrosive than others, causing failure of storage tanks.
In addition, salts used for deicing of service station areas
are thought to have increased the corrosiveness of the soil.
An interesting discovery was the fact that service stations
along streets that formerly had electric street car routes
tend to have a higher incidence of leaks from storage tanks.
This is believed to be caused by electrolytic corrosion of
tanks along these routes. Attempts are currently being made
in some states to draft corrosion protection laws for stor-
age tanks. Some oil companies and operators are changing
over to fiberglas tanks or other corrosion resistant mate-
rials in anticipation of such action.
During the first six months of 1973, the Department of Ecol-
ogy of the state of Washington recorded nearly 500 complaints
of oil spills, only a few of which affected ground-water
supplies. Of these spills, 213 were from unknown causes, 63
were directly attributed to human error, and the remainder
were due to such things as poor maintenance, deliberate dump-
ing, or equipment failure. 139)
Leaks and spills of petroleum products from several tank
farms in Idaho caused contamination of nearby domestic water
wells. 140) Spills at an oil refinery at Billings, Montana,
entered the ground water and discharged into the Yellowstone
River. 27) Spills at a refinery at the port of Pasco in
Washington have also caused ground-water contamination, and
in Colorado, refueling operations at railroad yards have
been found to contribute to ground-water and surface-water
contamination. 34,141)
In Montana, ground-water contamination from gasoline spills
has taken place in the town of Missoula. Two spills, each
of 3,800 to 7,500 liters (2,000 to 3,000 gallons) of gasoline,
313
-------
occurred in recent years forcing the abandonment of several
water wells. A similar problem occurred in the town of Deer
Lodge, where a municipal well became contaminated with gaso-
line. The'problem was solved by lining the well, excavating
the leaky tank, and installing a drain system to hold the
water table at a constant elevation. 27)
In Oregon, the State Engineer's Office receives reports of
one to two gasoline spills per year. 30) Contamination of
the ground-water supply by diesel fuel at the town of Pendle-
ton has occurred. This took place when a railroad tank car
accidentally spilled a load of diesel fuel over the infiltra-
tion gallery of the town's water system. 32)
Oil pipeline companies are required by federal regulations
to submit reports on oil spills when more than 2,000 liters
(50 barrels) of liquid are lost. In 1969, a total of 29
such spills was recorded by the U. S. Department of Trans-
portation. Thirteen incidents took place in Wyoming, ten in
Montana, four in Colorado, and two in Idaho. 142)
A large spill occurred in the Bellingham area of Washington
when a rupture occurred in a crude oil line and one million
liters (300,000 gallons) of crude oil spilled on the ground.
Fortunately, the break occurred on terrane underlain by
glacial till of low permeability, and oil did not penetrate
to deeper zones. The clean-up operation consisted of exca-
vating the contaminated soil. 139)
Leaks and spills of radioactive liquid wastes have taken
place at the NRTS and the Hanford Reservation. Many leaks
occurred because of corrosion and failure of buried waste
lines. 143) A serious leak took place at Hanford in June
1973 when failure of a steel tank caused the release of over
400,000 liters (115,000 gallons) of high-level radioactive
wastes. To investigate the impact of this leak, 16 wells
were drilled around the tank. Core samples indicated that
the lateral extent of the liquid contaminant was elliptical,
extending from 33 to 45 m (110 to 150 ft) from the tank cen-
ter. The maximum vertical penetration was 26 m (86 ft) be-
low ground level and 35 m (116 ft) above the regional water
table. The leakage was found to constitute no threat to pub-
lic health at the time of the investigation. Monitoring data
showed that the radioactivity had been retained in the soil
above the water table. It was determined that a driving
force to move the contaminant toward the ground-water system
did not exist. In addition, the investigators found that
the radioactive elements that might eventually reach the wa-
ter table would decay to a harmless level in the time re-
quired for the contaminant to reach the Columbia River. 144)
314
-------
FERTILIZERS AND PESTICIDES
Commercial chemical fertilizers used for improving crops
contain phosphates, nitrogen, and other plant nutrients.
Nitrates in water in excessive concentrations may cause
methemoglobinemia in infants, and for this reason the U. S.
Public Health Service standards limit the nitrate content of
drinking water to 45 mg/1. Cattle are also susceptible to
nitrate toxicity.
Application of fertilizers on the land surface has greatly
increased on a national basis, from 300,000 metric tons of
nitrogen in 1940 to almost 6.7 million metric tons in 1970.
145) For 1970, total fertilizer use in the Northwest was
1.7 million metric tons of which about 330,000 tons con-
sisted of phosphates. Most of the fertilizer was used in
Washington, Oregon, and Idaho (see Table 42). Although a
large amount, the fertilizer use in the Northwest is only
about 5 percent of the national use. In comparison, total
fertilizer use in California alone was 2.6 million metric
tons. Study of nitrates as a source of ground-water pollu-
tion is complicated by naturally occurring nitrogen in soils
and nitrates contributed from domestic sewage effluent and
animal wastes. 146,147)
Pesticides applied to crops and soil can enter the ground-
water system in several ways. Toxic contaminants can in-
filtrate the soil and migrate to the zone of saturation or
they can mix with surface runoff and enter the aquifer
through unprotected or poorly constructed water wells. The
rate of migration of the pesticide and subsequent contamina-
tion of the ground-water reservoir is dependent upon the
type of pesticide and the nature of the soil. Soluble pesti-
cides, such as 2,4-D are a larger threat to ground water
than relatively insoluble and immobile pesticides such as
aldrin, dieldrin, and DDT. 148)
Case Histories
An intensive study of soil profile and ground-water quality
was carried out in the South Platte Valley of Colorado. 149,
150) Cores were taken to the water table at 129 locations,
and cores and water samples were analyzed for nitrate con-
tent. The average nitrate content in the soil profile
varied greatly, but there was little difference in the ni-
trate content of the water (Table 43). Calculations based
on average nitrate content of the irrigated fields (exclud-
ing alfalfa) and the rate of water moving through these pro-
files suggested that 28.2 to 33.6 kg of nitrogen per hectare
(25 to 30 Ibs per acre) was lost annually to the water
315
-------
Table 42. CONSUMPTION OF COMMERCIAL FERTILIZERS IN 1970.
145)
Total fertilizers
Of which phosphates
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Short tons
257,898
423,206
178,644
440,292
541,645
60,984
Metric tons
233,965
383,932
162,066
399,433
491,380
55,325
Short tons
27,815
99,909
73,620
110,905
48, 236
8,363
Metric tons
25,234
90,637
66,788
100,613
43,760
7,587
Total:
1,902,669
1,726,101
368,848
334,619
316
-------
Table 43. CHEMICAL ANALYSES OF GROUND WATER BENEATH FEEDLOTS AND ADJACENT IRRIGATED FIELDS
IN THE SOUTH PLATTE VALLEY OF COLORADO. 151)
CO
Feedlot
Irrigated field
Feedlot
Irrigated field
Feedlot
Irrigated field
Feedlot
Irrigated field
Core
No.
7-E
7-B
9-F
9-C
9-E
9-J
16-B
16-D
Depth
to
water
table
(m)
10
10
5
3
4
3
11
11
NO3-N
(ppm)
8.6
0.1
18
31
21
8.5
1.1
18
NH4-N
(ppm)
5.1
0.0
5.7
0.1
5.8
0.0
38
0.4
Organic
c
(ppm)
130
18
130
12
90
9
170
26
P
(ppm)
0.25
0.06
0.36
0.04
0.22
0.01
1.3
0.05
Redox
potential
(mv)
- 340
300
- 310
360
340
430
100
430
-------
table. 151)
There is very little documented data of ground-water pollu-
tion caused by fertilizers and pesticides. However, concern
has been expressed about infiltration of these potential
pollutants in the zone of recharge of the Ogallala Formation
in eastern Colorado. In the San Luis Valley of Colorado,
heavy application of chemical fertilizers is the probable
cause of high nitrate concentrations (in excess of 45 mg/1).
152) in the same valley, some irrigators reportedly use
siphons on pumps to distribute liquid fertilizers with the
irrigation waters. When pumps are turned off these siphons
can let fertilizer flow into the well and into the aquifer.
153)
High nitrates have been attributed to heavy fertilizer ap-
plications in the major river valleys of Washington State.
These include the Columbia, Yakima, and Colville River ba-
sins. 154 through 157) Almost all counties in Washington in
which heavy irrigation and fertilizer application take place
have reported a high incidence of nitrate contamination;
however, the degree to which these reported cases are di-
rectly related to fertilizer application is unknown. 33)
The Washington State Department of Ecology reported only
one incident of water pollution from fertilizer use in 1970,
none in 1971, three in 1972, and none in the first six
months of 1973. 122,139) of all of these incidents only one
was a ground-water problem, and this was due to careless
handling by an industrial supplier.
High nitrates recorded in the alluvial aquifer of the Kali-
spell Valley in northwestern Montana are believed to be de-
rived from heavy application of commercial fertilizers. 158)
However, other sources of high nitrates such as feedlots and
septic tanks are also mentioned as possible causes.
Over 680 water samples from surface water and ground water
were tested to determine the effect of irrigation agriculture
on water quality in the Boise Valley in southwestern Idaho.
159) Most of the farms in this area are gravity irrigated,
and water application efficiencies are fairly low. The wa-
ter table is close to land surface, and many soils in the
valley contain clayey beds which limit downward water move-
ment. The ground water was found to contain more nitrate-
nitrogen than other water sources, a possible result of
leaching of nitrate from the soil by percolating irrigation
water or contribution from feedlots, dairies, and septic
tank drain fields. Ascertaining the actual nitrate sources
turned out to be difficult as the water table was close to
the ground surface. The ground water was also found to con-
318
-------
tain a relatively large concentration of both ortho and
total phosphorous (0.11 and 0.58 mg/1 respectively).
The cases of ground-water contamination by pesticides men-
tioned most frequently by county and state officials were
those resulting from accidental spills in the vicinity of a
well or into an irrigation canal with subsequent leaking of
the contaminant to the ground water. Potential problems
from pesticide container disposal was the next most-
mentioned problem. An example of ground-water contamination
from actual application of pesticides was reported in north-
western Oregon where shallow alluvial wells were found to be
contaminated with arsenic, believed to be derived from pest-
icide spraying in orchards. 120,160)
Canyon County in southern Idaho uses large quantities of
pesticide. No documented cases of ground-water contamina-
tion have been reported as yet, but many public agencies in
the state are concerned about the potential effect. 161)
The main problem in this area seems to be accidental spills
which occur each year during the peak-use period. In the
Idaho Falls area, there was a period of heavy use of diel-
drin for control of Weiss worm in potatoes. Although diel-
drin is no longer used, the pesticide will persist for some
time in the soil and presents a potential problem.
FEEDLOTS
Cattle feedlots generate a large amount of solid and liquid
waste that is deposited on the land surface. One steer in
a feedlot produces about one cu m (34 cu ft) of manure in
one year. A feedlot with 1,000 head of cattle produces 956
cu m (1,250 cu yd) of manure per year. In terms of BOD
(biochemical oxygen demand), each animal produces an amount
of waste equivalent to six people. A feedlot of 1,000 head
on about 4 ha (10 acres) of land produces wastes equal to
that from a town of 6,000 people. 162) One large feedlot in
Greeley, Colorado, handles over 100,000 head, and it has
been estimated that the waste produced at this facility is
about the same as from a city of one million people. 163)
Some of the constituents of the waste from a 1,000 pound
bovine on a daily and 140-day feeding period basis are given
in Table 44. Also given are the annual wastes produced by
360 head per acre.
The number of feedlots in the six states and their capaci-
ties are shown in Table 45. The total number of feedlots
has declined from 4,610 in 1963 to about 2,452 in 1973. How-
ever, the number of feedlots with a capacity of over 1,000
head increased from 263 to 392 in the same period. The
319
-------
Table 44. SOME OF THE CONSTITUENTS OF WASTE FROM A 1,000 POUND BOVINE.
163)
Wet manure and urine
Dry mineral matter
Dry organic matter
Water
Total nitrogen
Total phosphorous
Total potassium
Per day
(Ibs) °)
64
2.1
8.2
53.7
0.38
0.048
0.26
140 days
(Ibs)
8,960
294
1,148
7,518
55
6.7
36.4
360 head/acre
(tons)
4,200
144
540
30.7
24.9
3.2
16.8
per year
inches
a) one Ib = 0.454 kg
-------
Table 45. NUMBER AND CAPACITY OF FEEDLOTS IN THE NORTHWEST. 164)
Colorado
1963
1973
Idaho
1963
1973
Montana
1963
1973
Oregon
1963
1973
Washington
1963
1973
Wyoming
1963
1969
Under
1,000
head
1,200
426
820
492
574
236
536
310
579
165
638
_
1,000
to
1,999
25
66
36
26
17
31
25
8
19
9
_
2,000 4,000 8,000 16,000
to to to to 32,000
3,999 7,999 15,999 31,999 and over
26 15 14°)
51 25 18 19 4
13 11 a)
22 15 13 a)
6 3 - - -
20 11 7°)
11 9 -
10 4 4°) -
11 6 3
10°) 5°)
4a)
_ _ _ _ _
Number
of lots
over
1,000
head
80
183
60
76
26
69
45
26
39
21
13
17
Total
all
feed lots
1,280
609
880
568
600
305
581
336
618
186
613
448
a) Lots from larger size groups are included to avoid disclosing individuals.
321
-------
largest number of feedlots is in Colorado, where 19 feedlots
fall within the 16,000 to 31,999 head capacity, and four
have a capacity of 32,000 or over. 164)
Feedlot wastes are leached and washed away as the manure de-
composes. Runoff containing excessive quantities of nitro-
gen, phosphorous, potassium, and pesticides can enter sur-
face-water drainage systems. Buildup of constituents such
as nitrate in ground water results from direct percolation
through the feedlot, and percolation through waste disposal
areas and fields spread with manure. Organic materials and
coliform bacteria normally do not reach the water table. A
study of nitrates in Colorado (see Table 43) showed that
concentrations of nitrate below feedlots ranged from none to
over 5,000 pounds of nitrogen per acre across a 20-foot pro-
file. If all the nitrate from a one-acre feedlot containing
this high level of nitrate leached into the ground water, it
would raise the nitrate content of approximately 200 acre-
feet of water to 10 mg/1 nitrate-N, the maximum safe drink-
ing water limit set by the U. S. Public Health Service. 151)
However, denitrification was found to occur under feedlots,
and consequently it was believed that much of the nitrate
never reached the water table.
Documented cases of ground-water pollution due to feedlot
leachate are rare. Many cases of high nitrates in ground
water result from poor construction of water wells. Cor-
roded or perforated surface casing and lack of proper cement-
ing of wells allows pollution from surface sources to take
place. In northeastern Colorado, some stock water wells
near feedlots had to be abandoned because the water was un-
suitable even for livestock. 163) These feedlots were lo-
cated on alluvial fill material, the principal aquifer in
the area. Recently, the Colorado Department of Health
denied a feedlot permit to a company because it found that
the operation would cause contamination of shallow ground
water. 165) The U. S. Geological Survey in Colorado has
initiated hydrogeologic studies of potential feedlot sites.
166)
In Washington, many feedlots are believed to contaminate
ground water. The source of high nitrates is not clear as
many feedlots are located in areas of high septic-tank usage.
Most of the feedlots are located in the Yakima Valley and
the Columbia Basin.
In Idaho, feedlots are located mainly along the Snake River
from Idaho_Falls to Weiser. Feedlots, together with manure
pits on dairy and chicken farms, are considered potential
hazards and are under study by the University of Idaho, the
322
-------
Idaho Department of Environmental and Community Services,
and the U. S. Corps of Engineers. 167)
SALT-WATER INTRUSION
Coastal aquifers can be in contact with sea water, and under
natural conditions, fresh ground water is discharged into
the ocean. If, however, pumpage of ground water is suffi-
ciently large, the seaward flow of ground water decreases or
reverses causing sea water to advance inland into aquifers.
This phenomenon is called sea-water intrusion.
Relatively few cases of sea-water intrusion occur in the
Northwest, and it is not a major problem. More frequent are
cases of upward migration of saline water in inland areas.
The latter situation can develop where saline ground water
underlies fresh-water aquifers. Problems of this type were
discussed in Section V.
Case Histories
A survey of sea-water intrusion along coastal Washington was
made in the period 1966-68. 168) it was found that near the
Pacific Ocean and along most of the shoreline of the Strait
of Juan de Fuca, development of ground-water supplies was
localized, and in only a few cases did salt-water intrusion
affect more than one or two wells at any particular locality.
Intrusion along shorelines of Puget Sound is more pronounced
because of more intensive development of ground-water sup-
plies on the many islands and long, narrow peninsulas which
are readily susceptible to intrusion. Cases of sea-water
intrusion have been reported near Olympia, at Tacoma, in
northern Kitsap and northeastern Jefferson Counties, and in
Island County.
The situation in Washington is often complex, as many occur-
rences of saline ground water in the coastal area are prob-
ably due to "relict" sea water or connate water that has
been in the aquifer since deposition of the sediments.
A small public supply system serving 25 homes in a subdivi-
sion adjacent to Puget Sound experienced salt-water intru-
sion in their supply well. I59) Six other wells tapping the
same aquifer and serving about 200 homes were not affected.
Three public supply wells at Hyada Park, north of Tacoma,
were contaminated by sea water. Chloride content in the
wells was found to increase progressively during heavy pump-
ing in summer. Concentrations of chloride in wells ranged
up to 1,000 mg/1. An investigation by the U. S. Geological
323
-------
Survey showed that the vulnerability of the site to sea-
water contamination was related to a low rate of recharge.
Although precipitation was abundant - 800 to 1,600 mm or 32
to 64 inches per year - the low permeability of glacial till
mantling the upland area limited recharge to the aquifer.
170)
In Oregon, sea-water contamination has occurred in the
coastal region of Tillamook and Clatsop Counties. Four wa-
ter wells were found contaminated, two of which were heavily-
pumped industrial wells located adjacent to Taylor Bay. 171)
Upconing of saline water into fresh-water zones has occurred
in Oregon where saline water in sedimentary rocks underlying
basalts migrated upward. 39,172,173) Pumpage of a well and
lowering of the hydrostatic head caused saline-water intru-
sion in Portland. 174)
HIGHWAY DEICING SALTS
Each winter, highway departments apply salts (sodium chlo-
ride and calcium chloride) to their road networks to elim-
inate or control ice and snow. In many states, problems
stemming from this practice have now begun to show up, and
there is an increasing concern about the environmental dan-
gers caused by salt to vegetation, soil, and water supplies.
Deicing salts contaminate surface runoff, ponds, streams,
and ground water, principally near roadside areas. Sub-
stances added to deicing salts to prevent caking or to in-
hibit corrosion, such as sodium ferrocyanide and phosphorous
compounds, can be extremely toxic to human, animal, and fish
life. Deicing salts are potentially more harmful in arid
regions where less precipitation and less dilution take
place.
The use of deicing salts in the Northwest in the winter of
1966-67 is shown in Table 46. The total of 14,500 metric
tons of sodium chloride is very small compared to use of de-
icing salts elsewhere in the nation. 175) For example, the
state of Massachusetts alone has used 172,000 metric tons of
sodium chloride in a single winter season. Nevertheless, be-
cause of low precipitation and low flushing and dilution in
the arid zone, deicing salts can be a contributing factor in
deterioration of ground-water quality.
MASS BURIAL OF LIVESTOCK
Perhaps the least common and least documented potential haz-
ard to ground-water quality is mass burial of livestock.
Large numbers of stock sometimes die because of infectious
324
-------
Table 46. USE OF DEICING SALT (SODIUM CHLORIDE) IN THE NORTHWEST
IN THE WINTER OF 1966-67. l75)
State
Colorado
Idaho
Montana
Oregon
Washington
Wyoming
Short tons
7,000
1,000
4,000
1,000
2,000
1,000
Metric tons
6,350
907
3,629
907
1,814
907
Total:
16,000
14,514
325
-------
disease, such as blackleg or hoof rot, or because of a
severe winter storm. The common practice of disposal is to
bulldoze a large pit and bury the carcasses. In Glacier
County and western Pondera County on the Blackfeet Indian
Reservation, an estimated 500 head of cattle died in a
severe winter storm and were buried in dug pits at various
locations. 176)
326
-------
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SECTION VI
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328
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59. Welch, J. R., "The Mineral Industry of Montana," in:
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60. Slatick, E. R., "The Mineral Industry of Wyoming," in:
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61. U. S. Geological Survey, "The National Atlas of the
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62. Balster, C. A., and others, "Oil and Gas Development in
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63. Colorado Oil and Gas Conservation Commission, "Oil and
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331
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66. Bond, E. W., "Influence of Seismic Shot Programs on
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67. Conselman, F. B., "Geologic Aspects of the Brine Pollu-
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68. Reid, G. W., and L. E. Streebin, "Evaluation of Waste
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69. Oil and Gas Conservation Division, "Annual Review for
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70. Wyoming Oil and Gas Conservation Commission, "Wyoming
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71. Oil and Gas Conservation Commission, "1972 Oil and Gas
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72. Evans, D. M., "Man-made Earthquakes in Denver," Geo-
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73. Hoover, D. B., and J. A. Dietrich, "Seismic Activity
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74. Carey, Ted, "Shell Chemical Company Officials Defend
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75. Prouty, D., "Chemical Dump Studied," The Denver Post,
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332
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76. Williamson, Art, Cheyenne, Wyoming, Personal Communica-
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77. Sceva, J. E., "Liquid Waste Disposal in the Lava Ter-
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78. Robertson, J. B., and J. T. Barraclough, "Radioactive
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79. Abegglen, D. E., "The Effects of Drain Wells on the
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80. Higginson, R. K., Director, Idaho Department of Water
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81. Petri, L. R., "The Movement of Saline Ground Water in
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84. Konikow, L. F., "Modeling Mass Transport in a Shallow
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85. Jones, R. M., Denver, Colorado, Personal Communication,
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86. U. S. Geological Survey, Water Resources Division,
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333
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87. Mink, L. L., and others, "Effect of Early Day Mining
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Vol. 10, No. 1, January-February 1972.
88. Mink, L. L., and R. E. Williams, "Analysis of an Aquatic
Environment Receiving Domestic and Industrial Wastes,"
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ronmental Health, University of Missouri, Columbia,
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89. Galbraith, J. J., R. E. Williams, and R. L. Siems, "Mi-
gration and Leaching of Metals from Old Mine Tailings,"
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90. Williams, R. E., "The Role of Mine Tailings Ponds in Re-
ducing the Discharge of Heavy Metal Ions to the Environ-
ment, " Bureau of Mines, Open File Report, 1973, Univer-
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91. Williams, R. E., C. D. Kealy, and L. L. Mink, "Effects
and Prevention of Leakage from Mine Tailings Ponds,"
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3rd Quarter, 1973.
92. Bogan, R. H., "Problems Arising from Ground-Water Con-
tamination by Sewage Lagoons at Tieton, Washington,"
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tion, Robert A. Taft Sanitary Engineering Center, Tech-
nical Report W61-5, 1961.
93. Foxworthy, B. L., U. S. Geological Survey, Tacoma,
Washington, Personal Communication, 1974.
94. Bureau of Mines, "1971 Minerals Yearbook," U. S. De-
partment of the Interior, 1971.
95. U. S. Department of the Interior, "Surface Mining and
Environment," 1967.
96. U. S. Geological Survey, "Proposed Plan of Mining and
Reclamation, Big Sky Mine, Peabody Coal Company, Coal
Lease M-15965, Colstrip, Montana," Draft Environmental
Statement, 1973.
97. National Academy of Sciences, "Rehabilitation Potential
of Western Coal Lands," Ballinger Publishing Company,
Cambridge, Massachusetts, 1974.
98. Schrider, L. A., Laramie Energy Research Center, Per-
sonal Communication, February 1974.
334
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99. Arthur D. Little, Inc., "A Current Appraisal of Under-
ground Coal Gasification," Report prepared for U. S.
Bureau of Mines, NTIS: PB 209 274, 1972.
100. Wentz, D. A., "Effect of Mine Drainage on the Quality
of Streams in Colorado, 1971-72," Colorado Water Con-
servation Board, Water Resources Circular 21, 1974.
101. U. S. Geological Survey, "The National Atlas of the
United States: Plate 185 - Oil Shale and Tar Sands,"
1970.
102. Committee on Environmental Problems of Oil Shale, "En-
vironmental Problems of Oil Shale," State of Utah,
February 1971.
103. "Breakthrough Report in Oil Shale Technology," Rocky
Mountain News, Denver, Colorado, October 5, 1973.
104. Denver Research Institute, "Disposal and Environmental
Effects of Carbonaceous Solid Wastes from Commercial
Oil Shale Operations," Report prepared for National
Science Foundation, NTIS:PB-231796.
105. Ralston, D. R., and others, "Solution to Problems of
Pollution Associated with Mining in Northern Idaho,"
University of Idaho and Idaho Bureau of Mines,
NTIS:PB 230965, 1973.
106. Johnson, C. E., Personal Communication, 1974.
107. Brock, Dr. Darrell, Boise, Idaho, Personal Communica-
tion, 1974.
108. Millis, Robert, Lander, Wyoming, Personal Communica-
tion, 1974.
109. Sceva, J. E., "Water Quality Considerations for the
Metal Mining Industry in the Pacific Northwest," En-
vironmental Protection Agency, Region X, Report No.
Region X-3, 1973.
110. Hazle, A. J., Colorado Department of Health, Denver,
Colorado, Personal Communication, 1973.
111. Williamson, Art, Cheyenne, Wyoming, Personal Communi-
cation, 1974.
335
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112. Brittin, W. E., Ronald West, and Robert Williams, Ed-
itors "Air and Water Pollution," Proceedings of the
Summer Workshop, August 3-15, 1970, University of Colo-
rado, Colorado Associated University Press, Boulder,
Colorado, 1972.
113. Runnels, D. D. and W. R. Chappell, University of Colo-
rado, Personal Communication, 1974.
114. Linstedt, K. D., and P. Kruger, "Vanadium Concentra-
tion in Colorado River Basin Waters," Journal American
Water Works Association, February 1969-
115. Power, J. F., and others, "Nitrification in Paleocene
Shale," Science, Vol. 183, March 1974.
116. Qasim, S. R., and J. C. Burchinall, "Leaching from
Simulated Landfills," Journal Water Pollution Control
Federation, Vol. 42, No. 3, 1970.
117. Seitz, H. F., A. T. Wallace, and R. G. Williams, "In-
vestigation of a Landfill in Granite-Loess Terrane,"
Ground Water, Vol. 10, No. 4, 1972.
118. Robertson, D., Personal Communication, December 1973.
119. Glynn, J. H., Personal Communication, December 1973.
120. Leonard, A. R., U. S. Geological Survey, Portland,
Oregon, Personal Communication, 1973.
121. Sweet, H. R., and R. H. Fetrow, "Wood Waste Disposal
and Ground Water Pollution," State Engineer's Office,
Salem, Oregon, unpublished report, 1974.
122. Water Investigation Division, "Water Pollution Inci-
dents Reported in Washington State During 1970, 1971,
1972," Washington State Department of Ecology, Office
of Technical Services, 1973.
123. Price, Don, "Rate and Extent of Migration of a "One-
Shot" Contaminant in an Alluvial Aquifer in Keizer,
Oregon," U. S. Geological Survey Research 1967, Profes-
sional Paper 575-B, 1967, pp. 217-220.
124. Jones, P. H., and Eugene Shuter, "Hydrology of Radio-
active Waste Disposal in the MGR-ETR Area, National
Reactor Testing Station, Idaho," U. S. Geological
Survey Research 1962, Professional Paper 450-C,
Article 106, 1962.
336
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125. Barraclough, J. T., and others, "Hydrology of the Na-
tional Reactor Testing Station, Idaho," U. S. Geologi-
cal Survey, Open-file Report TID 4500, 1966.
126. Idaho Operations Office, "National Reactor Testing
Station - Radioactive Waste Management Information
1972 - Summary and Record to Date," U. S. Atomic En-
ergy Commission, IDO-10054, 1972.
127. Isaacson, R. E., "The Hanford Exploratory Deep Well,
Atlantic Richfield Hanford Company," U. S. Atomic En-
ergy Commission, DOC-ARH-SA-47, 1969.
128. Beard, S. J., and W. L. Godfrey, "Waste Disposal Into
the Ground at Hanford," Isochem Inc., Richland, Wash-
ington, 1967.
129. Newcomb, R. C., J. R. Strand, and F. J. Frank, "Geol-
ogy and Ground-Water Characteristics of the Hanford
Reservation of the U. S. Atomic Energy Commission,
Washington," U. S. Geological Survey, Professional
Paper 717, 1972.
130. Essig, T. H., "Radiological Impact of Hanford Wastes
Disposal on Ground-Water Quality," Battelle-Pacific
Northwest Laboratories, Richland, Washington, SA-3744,
1971.
131. Kipp, K. L., Jr., "Radiological Status of the Ground
Water Beneath the Hanford Project, January-June 1971,"
Battelle-Pacific Northwest Laboratories, Richland,
Washington, NTIS:BNWL-1649, 1972.
132. Brown, D. J., "Migration Characteristics of Radionu-
clides Through Sediments Underlying the Hanford
Reservation," U. S. Atomic Energy Commission, Isochem,
Inc., Richland, Washington, 150-SA-32, 1967.
133. Kipp, K. L., Jr., "Radiological Status of the Ground-
Water Beneath the Hanford Project, July-December 1972,"
Battelle-Pacific Northwest Laboratories, Richland,
Washington, NTIS:BNWL-1752, 1972.
134. U. S. Atomic Energy Commission, "Standards for Radia-
tion Protection," U. S. Atomic Energy Commission Manual,
Chapter 0524, Annex A, Table II, 1968.
135. Corley, J. P-, "Evaluation of Radiological Conditions
in the Vicinity of Hanford for 1967," Battelle-Pacific
Northwest Laboratories, Richland, Washington, NTIS:
BNWL 983, 1969.
337
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136. LaSala, A. M., Jr., and G. C. Doty, "Preliminary Eval-
uation of Hydrologic Factors Related to Radioactive
Waste Storage in Basaltic Rocks at the Hanford Reserva-
tion, Washington," U. S. Geological Survey, Open-file
Report, 1971.
137. Associated Press, "Gasoline Seepage Cleaned Up," The
Denver Post, June 1974.
138. Schneider, M. D., Denver, Colorado, Personal Communica-
tion, 1973.
139. Water Investigations Division, "Repo-rted Water Pollu-
tion Incidents in Washington State, January 1, 1973 -
June 10, 1973," State of Washington Department of
Ecology, Office of Technical Services, 1973.
140. Idaho, Confidential Communication, 1974.
141. Focke, A. C., Denver, Colorado, Personal Communication,
1973.
142. Office of Pipeline Safety, "Summary of Liquid Pipeline
Accidents Reports on DoT Form 7000-1," U. S. Depart-
ment of Transportation, 1970.
143. Paige, B. C., and others, "Evaluation of Hazards and
Corrosion of Buried Waste Lines in NRTS Soil," Allied
Chemical Corp., Idaho Falls, Idaho, ICP-1013, 1972.
144. "Preliminary Evaluation of Hanford Leak Published,"
Ground Water, Vol. 12, No. 3, May-June 1974.
145. U. S. Department of Agriculture, "Consumption of Com-
mercial Fertilizers in the United States," 1970.
146. Viets, F. G., Jr., "Fertilizer Use in Relation to Sur-
face and Ground Water Pollution," in: Fertilizer Tech-
nology and Use, 2nd Edition, Soil Science Society of
America, 1971.
147. Viets, F. G., Jr., "Soil Use and Water Quality - A
Look Into the Future," Agricultural and Food Chemistry,
Vol. 18, No. 5, September-October 1970.
148. Working Group on Pesticides, "Ground Disposal of Pesti-
cides: The Problem and Criteria for Guidelines,"
NTIS: PB-197-144, 1970.
338
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149- Stewart, B. A., and others, "Distribution of Nitrates
and Other Water Pollutants Under Fields and Corrals in
the Middle South Platte Valley of Colorado," U. S. De-
partment of Agriculture, ARS 41-124, 1967.
150. Stewart, B. A., and others, "Nitrate and Other Water
Pollutants Under Fields and Feedlots," Environmental
Science and Technology, Vol. 1, No. 9, September 1967.
151. Stewart, B. A., F. G. Viets, Jr., and G. L. Hutchinson,
"Agriculture's Effects on Nitrate Pollution of Ground-
water," Journal Soil and Water Conservation, Vol. 23,
No. 1, January-February 1968.
152. Emery, P. A., and others, "Water in the San Luis Val-
ley, South-Central Colorado," Colorado Water Conserva-
tion Board, Water Resources Circular 18, 1973.
153. Webb, K. W., Colorado Department of Public Health,
Personal Communication, 1973.
154. McNish, Robert, Tacoma, Washington, Personal Communica-
tion, 1974.
155. Morton, John, Richland, Washington, Personal Communica-
tion, 1974.
156. Maddox, George, Spokane, Washington, Personal Communi-
cation, 1974.
157. Gibbons, Merle, Pasco, Washington, Personal Communica-
tion, 1974.
158. Konizeski, R. L., and others, "Geology and Ground Wa-
ter Resources of the Kalispell Valley, Northwestern
Montana," Montana Bureau of Mines and Geology, Bulle-
tin 68, 1968.
159. Fitzsimmons, D. W., and others, "Nitrogen, Phosphorous
and Other Inorganic Materials in Waters in a Gravity
Irrigated Area," Transactions of American Society of
Agricultural Engineers, Vol. 15, No. 2, 1972, pp. 291-5.
160. Bartholomew, William, Salem, Oregon, Personal Communi-
cation, 1974.
161. State and County Officials, Boise, Idaho, Personal
Communications, 1974.
339
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162. U. S. Environmental Protection Agency, "Cattle Feed-
lots and the Environment," Region X Report, 1972.
163. Viets, F. G., Jr., "The Mounting Problem of Cattle
Feedlot Pollution," Agricultural Science Review, Vol.
9, No. 1, First Quarter, 1971.
164. U. S. Department of Agriculture, Colorado State Uni-
versity Cooperative Extension Service, 1973.
165. Gillies, N. P., Editor, "Protection of Ground Water
Cited as Basis for Denial of Feedlot Permit," Ground
Water Newsletter, Vol. 3, No. 16, August 1974.
166. Biesecker, J., Denver, Colorado, Personal Communica-
tion, 1974.
167. Lorimer, Robert, "Feedlot Pollution Data Spur Cautious
Optimisim," Idaho Statesman, February 11, 1974.
168. Walters, K. L., "Reconnaissance of Sea-Water Intrusion
Along Coastal Washington," State of Washington, Water-
Supply Bulletin 32, 1968.
169. County Sanitarian, Snohomish County, Washington, Per-
sonal Communication, 1973.
170. Kimmel, G. C., "Contamination of Ground Water by Sea-
Water Intrusion Along Puget Sound, Washington, an Area
Having Abundant Precipitation," U. S. Geological Sur-
vey, Professional Paper 475-B, 1963.
171. Schlicker, H. G., and others, "Environmental Geology
of the Coastal Region of Tillamook and Clatsop Coun-
ties, Oregon," Oregon Department of Geology and Min-
eral Industries, Bulletin 74, 1970.
172. Brown, S. G., "Problems of Utilizing Ground Water in
the West-Side Business District of Portland, Oregon,"
U. S. Geological Survey, Water-Supply Paper 1619-0,
-L Z? O J •
173. Hampton, E. R., "Geology and Ground Water of the
Molalla-Salem Slope Area, Northern Williamette Valley,
Oregon," U. S. Geological Survey, Water-Supplv Pacer
1997, 1972. ^
174. Price, Don, D. H. Hart, and B. L. Foxworthy, "Artifi-
cial Recharge in Oregon and Washington," U. S. Geo-
logical Survey, Water-Supply Paper 1594-C, 1962.
340
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175. The Salt Institute, "Survey of Salt, Calcium Chloride,
and Abrasive Use for Street and Highway Deicing in the
United States and Canada for 1966-1967," Alexandria,
Virginia.
176. Clasby, Michael, District Sanitarian, Personal Com-
munication, 1974.
341
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SECTION VII
RESEARCH AND OTHER NEEDS
TRENDS IN GROUND-WATER POLLUTION
Prior to examining research requirements for assessment,
control and monitoring of ground-water pollution, it is nec-
essary to review trends in subsurface contamination and
identify potential sources of such pollution. The two fac-
tors that may greatly influence patterns of contamination of
ground water are the expanding population in the urban zones
and the expected large-scale mining of oil shale and coal to
develop new sources of energy. The rise in urban population
will result in an expansion of the number of sewage treat-
ment plants and a corresponding increase in effluent dis-
charge to surface-water bodies. In the arid zone, this may
cause a further decline in the quality of stream water. As
recirculation takes place through irrigation, the ground-
water quality may also be affected. In the non-sewered
areas, an increase in population will result in more septic
tank construction. Especially in the mountain areas, pollu-
tion of ground water from septic tank effluent will increase.
Mining of oil shale and coal is a potential hazard to ground-
water quality because of leaching of waste piles and acid
drainage from strip-mined lands. Proposed coal gasification
or liquification plants will require large quantities of de-
mineralized water, and the brine produced must be disposed
of either in impoundments or by deep-well injection.
Drilling of deep exploratory oil, gas and water wells will
continue probably at an increasing pace in view of the pres-
ent energy crisis, and so will potential ground-water pollu-
tion from improperly sealed holes. Fewer geophysical test
holes will be drilled in the future because geophysical com-
panies are shifting to surface energy systems that require
fewer shot holes. Laws requiring proper plugging of aban-
doned wells have been enacted in Colorado, Montana, and Wyo-
ming, but only with strong inspection and enforcement will
this potential source of contamination be reduced.
The number of landfills for municipal and industrial waste
will increase, but these waste disposal sites are now under
close scrutiny by state environmental and health departments.
Proper engineering design of waste dumps and monitoring of
ground-water quality and leachate production will tend to
reduce the incidence of ground-water pollution.
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According to the Federal Water Pollution Control Act Amend-
ment of 1972, discharge of toxic pollutants by industry will
be controlled by effluent standards set by the Environmental
Protection Agency in 1974, and industries must use the "best
practicable" water-pollution control technology by July 1,
1977. Because of this legislation, industry is moving from
direct discharge of waste liquids into rivers and streams to
impoundments. Leakage from unlined storage basins poses a
threat to ground-water quality. This problem is expected to
increase considerably in future years along with the poten-
tial for ground-water pollution from land treatment of
municipal and industrial waste waters.
In the agricultural sector, the demand for more food and
larger crops will result in large applications of both fer-
tilizers and pesticides. Irrigated agriculture in the arid
zone will cause a continuation of build-up of salts in the
subsurface. Proper drainage and irrigation management are
tools needed to halt this trend. The saline seep problem in
dryland areas of Montana and adjacent states is serious and
may be expected to increase. Change in crop patterns and
farming practices may be needed to control this ground-water
pollution problem. Feedlot operations appear to be shifting
to fewer lots but higher capacities. Contamination of shal-
low ground water from existing feedlots will continue, but
the problem will probably decrease in future years due to
stricter governmental control. State and federal agencies
are actively reviewing potential pollution problems from
proposed new feedlots.
Radioactive waste disposal will decrease at some installa-
tions as reactors are phased out. Leaks and spills, however,
will continue to be a serious source of ground-water pollu-
tion, and the number of such incidents is expected to grow
along with increased population and industrial activity.
GENERAL RESEARCH NEEDS
A general need for proper assessment and control of ground-
water contamination is basic information on geologic and
hydrologic conditions, water quality and identification of
sources of ground-water pollution. As of 1965, only approx-
imately 40 percent of the Northwest had been covered by re-
connaissance or general ground-water investigations, and
only 5 percent by detailed evaluations. In recent years,
there has been a considerable increase in ground-water in-
vestigations on both state and federal levels but ground-
water conditions over large portions of the study region re-
main essentially unknown.
343
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This lack of data is also reflected in the quantity and type
of data on water quality. There is a distinct lack of base-
line water-quality data and a definite need for preparing
this type of information so that degradation of water qual-
ity can be detected in the future. Laboratories should be
set up on a regional or county basis and ground-water and
surface-water sampling and analysis should be carried out on
a regular basis. In addition to routine analyses, trace
constituents should be checked periodically to detect organic
and inorganic compounds and to identify particularly harmful
pollutants, such as carcinogens. These analyses should be
standardized so that water quality can be more readily com-
pared from one area to another.
Standardized methods for reporting and collecting data on
incidents of ground-water pollution should be developed so
that cases can be quickly evaluated and remedial action can
be taken immediately to correct the situation. Perhaps a
computer printout system of pollution incidents similar to
that in use by the Department of Environment in Washington
would be useful in the individual states.
State governments should set aside a larger portion of their
financial resources for the protection of ground-water re-
sources. This will enable administrators to acquire the
necessary professional staff and to plan and carry out
ground-water quality investigations. At the present time,
the staff and personnel in charge of ground-water resources
in several states are solely administrators of water rights
and either have no authority to investigate cases of ground-
water contamination or have insufficient personnel to make
thorough investigations. Most departments have no field in-
spection team to monitor compliance with existing regula-
tions regarding construction and abandonment of wells. In
some cases, the responsibility for investigation of ground-
water pollution is not clearly defined between state agen-
cies .
There is also considerable reluctance on the part of many
state and county officials to discuss pollution problems.
In the future, with better administration and coordination,
the various officials should cooperate and share their in-
formation freely. For the above reasons, information on
ground-water pollution is difficult to obtain. It is virtu-
ally certain that only a very small percentage of the exist-
ing problems have been discovered to date. The impact of
the oil and gas industry, for example, on ground-water qual-
ity is essentially unknown. There is a definite need to
study oil-field regions and injection systems to assess the
potential hazard of brine or waste injection to fresh-water
344
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aquifers. It is true that much industrial development is
taking place in sparsely populated areas, but in the arid
zone fresh ground water is difficult to develop and measures
should be taken to protect such aquifers from degradation to
insure their availability to meet future needs.
Further investigations to inventory and evaluate ground-
water contamination should be a major concern of public
water-resources agencies. Perhaps each agency can start to
inventory, for example, each industrial waste-disposal site,
sewage lagoon, mine tailings dump, landfill operation and
oil pipeline. Aerial photographic techniques, including re-
mote sensing and multispectral photography could be useful
for this purpose. Records of flow and discharge of waste
effluent could be assembled so that potential problems can
be more easily evaluated. To deal with existing problems of
ground-water contamination, standard techniques call for the
drilling and testing of monitoring wells, and collection of
water samples. Installation of such wells is by far the
most expensive part of any investigation, and research is
needed to devise better and more economical methods for ob-
taining subsurface information. Additional research in geo-
physical techniques could probably refine the present map-
ping techniques to obtain better definition of bodies of
liquid waste below land surface.
After the initial evaluation of polluted ground water has
been made and the hydrologic environment has been estab-
lished, measures can be taken to contain the contaminants
and prevent them from further spreading in the aquifer zone.
This containment could be carried out by manipulation of
hydraulic gradients through controlled pumping operations;
by prohibiting or restricting pumping in a specified zone
surrounding the contaminated area; or by physical contain-
ment by means of artificially injected hydraulic barriers.
Removal of contaminated ground water by pumping or excava-
tion is generally undertaken, although it is rarely possible
to completely eliminate the pollutant. Research on better
methods to remove such pollutants as hydrocarbons from the
unsaturated and saturated zone is certainly warranted.
Obviously, the best way to reduce future cases of ground-
water contamination is through education of the general pub-
lic and through legislation and enforcement of regulations.
There is an urgent need to acquaint the public with the
serious consequences of ground-water pollution and the large
financial expenditures required to contain or remove under-
ground pollution.
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SPECIFIC NEEDS
An attempt has been made in Table 47 to assign research and
control priorities to the various sources of ground-water
contamination. Some of these sources have been already
studied for many years. For example, radioactive waste dis-
posal has received a great deal of attention in the past two
decades and a considerable amount of research on the impact
on ground water has been, and still is, carried out. Re-
search needs for this source of ground-water contamination
are thus rated as less important at this time than other
sources that have been studied to a lesser degree, such as
those related to sewage effluent, agricultural practices,
brine injection and surface impoundments.
Septic Systems
1. Improve septic-tank system design to provide better
treatment.
2. Initiate land-use management techniques that emphasize
protection of ground-water quality from the effects of
on-site waste disposal systems.
3. Require regional hydrogeologic reports providing such
data as depth to bedrock, major joint patterns, soil
conditions, and aquifer characteristics in order to
assist in evaluation of permit applications for septic
systems, where large-scale community development is pro-
posed.
Sewage Treatment Plant Discharge
1. Continue research on the travel, dispersion and fate of
organic and inorganic constituents in sewage-plant ef-
fluent and surface water under conditions of river in-
filtration in the semi-arid zone.
2. Study hydrogeological conditions downstream of individ-
ual sewage plant discharges to assess possible recircu-
lation of water and possible degradation of ground water.
Irrigation Return Flow
1. Continue research and evaluation of simulation modeling
techniques in irrigated stream-aquifer areas. First re-
sults indicate that modeling can be used to predict the
rates and direction and movement of contaminants in sur-
face _ and ground water, and that in the future it may be
possible to improve ground-water quality or limit salin-
346
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Table 47. PRINCIPAL SOURCES OF GROUND-WATER CONTAMI NATION AND
THE PRIORITY FOR ADDITIONAL RESEARCH AND CONTROL IN THE
NORTHWEST.
Sources
Septic systems
Sewage treatment plant discharge
Irrigation return flow
Dryland farming
Abandoned oil wells and test wells
Brine injection
Disposal wells
Surface impoundments
Mine drainage and mine tailings
Urban and industrial landfills
Radioactive waste disposal
Leaks and spi Ms
Fertilizers and pesticides
Feedlots
Salt-water intrusion
Coastal region
Inland region
Highway deicing salts
Mass burial of livestock
Research
Control
-High
- Moderate
- Low
347
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ity increases in rivers during low-flow periods.
Dryland Farming
1. Continue research on the relationship between dryland
farming and saline seep occurrence.
2. Evaluate the present and future impact of saline seeps
on ground-water and surface-water quality in the north-
ern Great Plains states.
Abandoned Oil Wells and Test Wells
1. Enforce regulations requiring proper sealing and plug-
ging of abandoned wells to prevent migration of fluids
between formations and provide periodic field inspection
of such operations.
2. File records of locations of abandoned oil wells, geo-
logic and geophysical holes, together with relevant sub-
surface and construction details at state environmental
agencies, to be available for consultation in the event
of a contamination problem in a particular area.
3. Institute joint state and private industry programs
for selecting abandoned wells for conversion to ground-
water monitoring wells.
Brine Injection
1. Define the magnitude of the problem of ground-water qual-
ity deterioration from brine or waste-water injection by
the petroleum industry.
Disposal Wells
1. Further investigate the impact on ground-water quality
of discharge of excess irrigation water, storm runoff or
liquid waste to shallow disposal wells in fresh-water
aquifers.
2. Determine areas that are geologically and hydrologically
suitable for deep-well disposal of liquid wastes.
Surface Impoundments
1. Evaluate in greater detail the impact on ground-water
quality of the increasing practice of using surface im-
poundments for storage and treatment of liquid waste.
348
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2. Prepare inventories of existing surface impoundments,
obtain information on the character of materials being.
stored, and determine lining conditions and volumes of
wastes discharged.
3. Assess hydrogeological conditions of each proposed, ex-
isting, and abandoned surface impoundment area to assess
possible contamination of ground water.
4. Develop long-life impervious liners that are better able
to withstand attack by impounded material.
Mine Drainage and Mine Tailings
1. Continue research into the feasibility of minimizing
discharge from active and abandoned surface and deep
mines.
2. Research the feasibility of sealing aquifer zones in
coal strip-mining areas to prevent or reduce discharge
of ground water to excavations and halt dewatering of
aquifers.
3. Inventory baseline surface and ground-water quality, and
determine the impact on ground-water and surface-water
resources prior to commencement of new mining operations.
4. Continue research into methods for minimizing leachate
from mine tailings.
5. Evaluate the quantity and quality of water presently
stored in abandoned mines for possible future use.
6. Determine the possible impact of sand and gravel and
placer mining operations on ground-water quality.
Urban and Industrial Landfills
1. Prepare inventories of industrial and municipal land-
fills and review climatic and hydrogeologic conditions
at each existing and planned landfill site to determine
the possible threat to ground-water quality.
2. Enforce regulations prohibiting disposal of toxic wastes
in landfills.
3. Research potential ground-water quality degradation from
composted shredded solid waste, such as wood and food-
processing waste disposed on the land surface.
349
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Radioactive Waste Disposal
1. Continue research into simulation modeling of waste
plumes and ultimate fate of radioactive waste fluids.
Leaks and Spills
1. Develop an improved reporting system of pollution acci-
dents and abatement procedures on a state-wide level.
2. Evaluate soil and ground-water conditions along oil, gas
and mining product pipelines to assess potential hazard
from spills or pipeline breaks.
Fertilizers and Pesticides
1. Further research the fate of pollutants from application
of fertilizers and pesticides in soil overlying recharge
zones of regional aquifers.
2. Investigate the impact on ground-water quality from the
use of liquid fertilizer siphons installed on irrigation
wells.
Feedlots
1. Inventory feedlots and review hydrogeologic conditions
at existing and planned feedlot sites to assess possible
danger of ground-water contamination.
Salt-Water Intrusion
1. Continue investigation into defining those areas that
are susceptible to salt-water intrusion in coastal and
inland areas.
2. Investigate the need for legislation by state and local
agencies to control well spacing and pumping rates in
critical areas.
Highway Deicing Salts
1. Assess the importance of this source of contamination.
Mass Burial of Livestock
1. Assess the severity of this potential problem and the
possible impact on ground-water quality.
350
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APPENDICES
Appendix Page
A Glossary of Terms 352
B Water Quality Standards 358
C Constants and Conversion Factors 360
351
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SECTION VIII
APPENDIX A - GLOSSARY OF TERMS
Acre foot - A unit for measuring the volume of water. It is
equal to the amount of water needed to cover one acre of land
with water one foot deep.
Alluvium - Clay, silt, sand, gravel, or other rock materials
transported by flowing water and deposited in comparatively
recent geologic time as sorted or semi-sorted sediments in
riverbeds, estuaries, floodplains, and in fans at the base
of mountain slopes.
Aquifer - A geologic formation, group of formations, or part
of a formation that is water yielding.
Artesian - The occurrence of ground water under sufficient
pressure to rise above the upper surface of the aquifer.
Artesian Aquifer - An aquifer overlain by a confining bed and
containing water under artesian conditions.
Artificial Recharge^ - The addition of water to the ground-
water reservoir by activities of man, such as irrigation, or
spreading basins.
Base Flow - The fair-weather flow of streams, composed large-
ly of ground-water discharge.
Biochemical Oxygen Demand (BOD)- The quantity of oxygen util-
ized primarily in the biochemical oxidation of organic matter
in a specified time and at a specified temperature. The time
and temperature are usually five days and 20°C.
Brackish Water - Water containing dissolved minerals in ex-
cess of acceptable potable water standards, but less than
that of sea water.
Chemical Water Quality - The nature of water as determined
by the concentration of chemical constituents.
Concentration - The weight of solute dissolved in a unit
volume of solution.
Connate_Water - Water that was deposited simultaneously with
the sediments, and has not since then existed as surface
water or as atmospheric moisture.
352
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Consumptive Use - The quantity of water discharged to the at-
mosphere or incorporated in the products of vegetative growth
or industrial processes.
Contamination - The degradation of natural water quality as
a result of man's activities, to the extent that its useful-
ness is impaired.
Crystalline Rock - A general term for igneous and metamorphic
rocks as opposed to sedimentary rocks.
Degradable - Capable of being decomposed, deteriorated, or
decayed into simpler forms with characteristics different
from the original. Also referred to as biodegradable.
Degradation of Water Quality - The act or process of reducing
the level of water quality so as to impair its original use-
fulness .
Demineralization - The process of reducing the concentration
of chemical constituents.
Domestic Well - A well which supplies water for the occupants
of a single residence.
Drawdown - The lowering of the water table or piezometric
surface caused by pumping or artesian flow.
Effluent - A waste liquid, in its natural state, or partially
or completely treated that discharges into the environment.
Evapotranspiration - The combined processes of evaporation
from land, water, and other surfaces, and transpiration by
plants.
Feedlot - A relatively small, confined land area for raising
and fattening cattle.
Floodplain - The flat ground along a stream course which is
covered by water at flood stage.
Fluvial Sediment - Those deposits produced by stream or river
action (see Alluvium).
Glacial Drift - Boulders, till, gravel, sand or clay trans-
ported by a glacier or its meltwater.
Ground Water - Water beneath the land surface that is under
atmospheric or greater pressure - the water that enters wells
and issues from springs.
353
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Ground-Water Recharge - The natural processes by which water
is added to a ground-water reservoir.
Ground-Water Reservoir - The earth materials and the inter-
vening open spaces that contain ground water.
Half-life (Radioactive) - The time in which one-half of the
atoms in a radioactive substance disintegrate.
Hard Water - Water with over 60 mg/1 of hardness.
Hardness - A property of water caused by the presence of cal-
cium and magnesium, which is reflected in the amount of soap
necessary to form suds and incrustations in appliances and
pipes when the water is heated. It is expressed as an equiv-
alent amount of calcium carbonate.
Heavy Metals - Metallic elements with high molecular weights,
generally toxic in low concentrations to plant and animal
life. Examples are: mercury, chromium, cadmium, arsenic,
and lead.
Igneous Rock - Rock formed by the solidification of molten
material that originated within the earth.
Industrial Well - A well used for the supply of water util-
ized in an industrial process.
Infiltration - The flow of a liquid into soil or rock through
pores or small openings.
Irrigation Return Flow - Irrigation water which is not con-
sumed in evaporation or plant growth, and which returns to a
surface stream or ground-water reservoir.
Lacustrine - Deposits which have accumulated in lakes or
marshes.
Lagoon - A shallow pond, usually man-made, to treat municipal
or industrial waste water.
Leachate - The liquid that has percolated through the soil or
other medium and has extracted dissolved or suspended mate-
rials from it.
Metamorphic Rock - A rock which has been altered by heat or
intense pressure, causing new minerals to be formed and new
structures in the rock.
Metasedimentary Rock - A metamorphosed sedimentary rock.
354
-------
Milligrams Per Liter - The weight in milligrams of any sub-
stance contained in one liter of liquid. Approximately
equivalent to parts per million.
Mineralization - The natural process of accumulation of min-
eral elements and/or compounds in soil or water.
Natural Brines - A highly saturated solution of soluble min-
erals, usually found in rocks associated with salt deposits
or as a result of sea water evaporation.
Natural Leaching - The removal by a solvent of the more sol-
uble minerals in soil or rocks by percolating waters.
Nutrients - Compounds of nitrogen, phosphorous, and other
elements essential for plant growth.
Outwash - Stratified glacial drift that is deposited by melt-
water streams.
Perched Ground Water - An isolated body of ground water sepa-
rated from the underlying main body of ground water by an
unsaturated zone.
Percolation - Movement under hydrostatic pressure of water
through interstices of rock or soil.
Permeability - A measure of the capacity of a porous medium
to transmit fluid.
Pesticides - Chemical compounds used for the control of un-
desirable plants, animals, or insects. The term includes in-
secticides, herbicides, rodent poisons, nematode poisons,
and fungicides.
Piezometric Surface - The surface defined by the levels to
which water will rise in tightly cased wells. Also called
potentiometric surface.
Plume - An area of contaminated ground water originating from
a point source and influenced by such factors as the local
ground-water flow pattern, density of pollutant, and char-
acter of the aquifer.
Point Source - A stationary source of ground-water pollution.
Pollutants - Substances that may become dissolved, suspended,
absorbed or otherwise contained in water, and impair its
usefulness.
355
-------
Pollution - The degradation of natural water quality, as a
result of man's activities, to the extent that its useful-
ness is impaired.
Porosity - The relative volume of the pore spaces between
mineral grains in a rock as compared to the total rock vol-
ume.
Primary Treatment (Sewage) - The removal of larger solids by
screening, and of more finely divided solids by sedimenta-
tion.
Production Well - A well from which ground water is obtained.
Public Supply Well - A well from which ground water is ob-
tained serving more than one individual or household.
Salt-Water Intrusion (or Encroachment) - Movement of salty
ground water so that it replaces fresh ground water.
Saturation, Zone of - The zone in which interconnected inter-
stices are saturated with water under pressure equal to or
greater than atmosphere.
Sedimentary Rock - Rocks formed by the accumulation of sedi-
ment.
Soft Water - Water containing 60 mg/1 or less of hardness.
Sorption - A combination of adsorptive and other physiochem-
ical interfacial forces that removes pollutants from solu-
tion and retains them on fine-grained materials. Sorption
may include ion exchange and precipitation processes.
Specific ^Capacity - The rate of discharge of water from a
well divided by the drawdown of the water level in it. Prop-
erly stated, it relates to the time of pumping.
Storage (Aquifer) - The volume of water held in the inter-
stices of the rock.
Surface Water - That portion of water that appears on the
land surface.
Transmissivity - The rate at which water is transmitted
through a unit width of the aquifer under a unit hydraulic
gradient.
Trona ~ A natural sodium sesquicarbonate and source of sodium
compounds.
356
-------
Unconsolidated Rocks - Uncemented or loosely coherent rocks.
Water Cycle - The complete cycle through which water passes;
water vapor in the atmosphere, liquid and solid as precipi-
tation as part of surface and ground water and eventually
back to atmospheric vapor.
Water Quality - Pertaining to the chemical, physical and bio-
logical constituents found in water and its suitability for
a particular purpose.
Water Table - That surface in an unconfined water body at
which the pressure is atmospheric. It is defined by the lev-
els at which water stands in wells that penetrate the water
body just far enough to hold standing water.
Water-Table Aquifer - An aquifer containing water under wa-
ter-table conditions.
357
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SECTION VIII
APPENDIX B - WATER QUALITY STANDARDS
The levels of mineralization or contamination which can be
tolerated in ground water are dependent upon the use in-
tended for water. Recommended water-quality standards are
available for agricultural, industrial, and public-supply
needs. Certain chemical constituents can be tolerated
through a wide range of concentrations without adverse ef-
fects even in stringent cases requiring excellent water
quality, while other constituents can be acceptable only at
minute levels or not at all. Clearly then, the water qual-
ity standards for any particular use are varied and in most
cases well documented. It is evident that to list each and
every guideline is beyond the scope of this report.
As mentioned in Section V, the allowable chemical limits for
potable public water supplies for each state are generally
similar to the standards of the U. S. Public Health Service.
In some states, the chemical concentrations currently al-
lowed are in the process of review. In the near future,
some revisions in permissible levels of certain constituents
will be adopted, and analyses of constituents not now listed
may be required. The most recent standards established by
the U. S. Public Health Service for water supply are pre-
sented in Table 48.
358
-------
Table 48. U. S. PUBLIC HEALTH SERVICE CHEMICAL STANDARDS
OF DRINKING WATER, 1962.
Category A - Maximum allowable concentrations where other more suitable supplies
are, or can be made available:
Substance Concentration in mg/l
Alkyl Benzene Sulfonate (ABS) 0.5
Arsenic (As) 0.01
Chloride (Cl) 250
Copper (Cu) 1
Carbon Chloroform Extract (CCE) 0.2
Cyanide (CN) 0.01
Iron (Fe) 0.3
Manganese (Mn) 0.05
Nitrate (NO3) a) 45
Phenols 0.001
Sulfate (SO4) 250
Total Dissolved Solids (TDS) 500
Zinc (Zn) 5
Category B - Maximum concentrations which shall constitute ground for outright
rejection of the supply:
Substance Concentration in mg/l
Arsenic (As) 0.05
Barium (Ba) 1.0
Cadmium (Cd) 0.01
Chromium (Hexavalent) (Cr+6) 0.05
Cyanide (CN) 0.2
Fluoride (F) 0.6 to 1.7 b)
Lead (Pb) 0.05
Selenium (Se) 0.01
Silver (Ag) °-05
a) In areas in which the nitrate content of water is known to be in excess of the
listed concentration, the public should be warned of the potential dangers of
using the water for infant feeding.
b) Varies with water temperature.
359
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SECTION VIII
APPENDIX C - CONSTANTS AND CONVERSION FACTORS
Volume
1 gallon (g)
1 cubic foot (cu ft)
1 acre-foot (acre-ft)
1 liter (1)
1 cubic meter (cu m)
1 cubic hectometer (cu hm)
1 barrel (oil)
1 million gallons
Flow Rate
1 gallon per minute (gpm)
1 million gallons per day (mgd)
1 billion gallons per day (bgd)
1 cubic foot per second (cfs)
1 acre-foot per day
1 liter per second (1/s)
1 cubic meter per second (cu m/s)
1 cubic meter per day (cu m/d)
1 cubic hectometer per day (cu hm/d)
3.785 liters
3.785 x 10-3m3
7.481 gal
28.32 liters
3.259 x 105 gal
1,234 m3
0.2642 gal
1,000 cm3
264.2 gal
1,000 liters
42 gal
3.069 acre-feet
3,785.4 m3
0.0631 I/sec
5.42 m3/day
43.7 I/sec
3,785 m3/day
3.785 hm3/day
449 gpm
28.3 I/sec
14.2 I/sec
15.9 gpm
86.4 m3/day
22.8 mgd
35.3 cfs
0.183 gpm
264.2 mgd
Pressure
1 pound per square inch (psi)
1 kilogram per square centimeter (kg sq cm)
0.07031 kg/cm2
14.22 lb/in2
Transmissivity
1 sq m/day
= 80.5 gpd/ft
360
-------
Length
1 inch (in)
1 foot (ft)
1 mile (mi)
1 centimeter
1 meter (m)
(cm)
1 kilometer (km)
2.54 cm
30.48 cm
1.609 km
0.3937 in
10 mm
39.37 in
3.2808 ft
100 cm
0.621 mi
1,000 m
10 hm
Area
1 acre
1 square mile (sq mi)
1 hectare (ha)
1 square kilometer (sq km)
0.4047 hectare
2.590 km2
2.471 acres
247.1 acres
0.3861 mi2
100 hectares
Weight
1 pound (Ib)
1 short ton
1 metric ton
1 kilogram (kg)
0.4536 kg
2,000 Ib
0.9072 metric ton
1,000 kg
2.205 Ib
361
-------
SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
I".;. .Report No.
'' 3. Accession No.
w
4, Title
GROUND WATER POLLUTION PROBLEMS IN
THE NORTHWESTERN UNITED STATES
7. Authar(s)
Frits van der Leeden, Lawrence A0 Cerrillo, and David W0 Miller
Is., Report Dat<
5, Pqtformin* Organization
Report JVo. "
9. Organization
Geraghty & Miller, Inc0
Port Washington, New York 11050
10. Project ffo.
tl. Contract/ Grant No.
68-03-0298
'Tl!,2i« ffSp0T3&Q£lHjj£ C^rjgilltliUX&ttOXt j**1* * * ' * "*»«** ^*- »"* ^* v ^ " >• *",
JLuSLajtJil>«^ii*..iii /i- .-JtJSi-k'li— " -is^a!! * "**" W«» -**, * ' * I" * ' ,"? w"^*, * ^» k ^ ^ * *"• '*V *" *. f -w ^F
13. _ -Type erf Report and"" >• ' "r
Period Cove fed
IS,
Environmental Protection Agency Report No0 EPA -3-75-018
16. Abstract An evaluation of ground-water pollution problems has been carried out in six states
in the northwest: Colorado, Idaho, Montana, Oregon, Washington and Wyoming,, The findings
of the investigation indicate that, with the exception of radioactive waste disposal, few cases
of ground-water pollution have been investigated in detail. There is a need for baseline water-
quality data and systematic evaluation of overall ground-water conditions, especially in urban
zones, in areas of petroleum exploration and development, and at locations of mining and indus-
trial activity,, The most common natural ground-water quality problems, other than high salinity,
are excessive hardness, iron, manganese, and fluoridea Principal sources of man-caused ground-
water quality problems in the approximate order of severity are: discharge of effluent from septic
tanks and sewage treatment plants, irrigation return flow, dryland farming, abandoned oil wells,
shallow disposal wells, unlined surface impoundments, mine tailings and mine drainage,
municipal and industrial landfills, and radioactive waste disposal. Other sources that appear to
be of less importance but still must be considered include: spills and leaks, application of
fertilizers and pesticides, feedlots, and salt-water intrusion,,
17a. Descriptors
* Ground water, mine wastes, salinity, septic tanks, water pollution, water quality,
water resources, waste dumps, wells,,
17b. Identifiers
Northwestern United States, Colorado, Idaho, Montana, Oregon, Washington, and Wyoming,
17c. COWRR Field & Group
18. Availability
19. St turity C' t$s.
(Report)
20. Security Class,
21, A'o. of
3JH«
C2. Price
Send To:
WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON, D. C. 2O24O
AbstrrA or
Marion R. Scalf
Institution
n Ro S. Kerr Environmental Research Laboratory
ft U.S. GOVERNMENT PRINTING OFPICE: 1975-698-474 (144 REGION 10
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