THE MINERAL QUALITY PROBLEM
IN THE COLORADO RIVER BASIN
SUMMARY REPORT
UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
REGIONS VIII and IX
1971
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THE MINERAL QUALITY PROBLEM
IN THE COLORADO RIVER BASIN
SUMMARY REPORT
UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY
REGIONS VIII AND IX
1971
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THE ENVIRONMENTAL PROTECTION AGENCY
The Environmental Protection Agency was established
by Reorganization Plan No. 3 of 1970 and became
operative on December 2, 1970. The EPA consolidates
in one agency Federal control programs involving air
and water pollution, solid waste management, pesticides,
radiation and noise. This report was prepared over a
period of eight years by water program components of
EPA and their predecessor agencies—the Federal Water
Quality Administration, U.S. Department of Interior,
April 1970 to December 1970; the Federal Water Pollution
Control Administration, U.S. Department of Interior,
October 1965 to April 1970; the Division of Water
Supply and Pollution Control, U.S. Public Health
Service, prior to October 1965. Throughout the report
one or more of these agencies will be mentioned and
should be considered, as part of a single agency--in
evolution.
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PREFACE
The Colorado River Basin Water Quality Control Project was
established as a result of recommendations made at the first
session of a joint Federal-State "Conference in the Matter
of Pollution of the Interstate Waters of the Colorado River
and Its Tributaries," held in January of 1960 under the
authority of Section 8 of the Federal Water Pollution Control
Act (33 U.S.C. 466 et seq.). This conference was called at
the request of the States of Arizona, California, Colorado,
Nevada, New Mexico, and Utah to consider all types of water
pollution in the Colorado River Basin. The Project serves
as the technical arm of the conference and provides the
conferees with detailed information on water uses, the
nature and extent of pollution problems and their effects
on water users, and recommended measures for control of
pollution in the Colorado River Basin.
The Project has carried out extensive field investigations
along with detailed engineering and economic studies to
accomplish the following objectives:
(1) Determine the location, magnitude, and causes of
interstate pollution of the Colorado River and its
tributaries.
(2) Determine and evaluate the nature and magnitude of
the damages to water users caused by various types
of pollution.
(3) Develop, evaluate, and recommend measures and
programs for controlling or minimizing interstate
water pollution problems.
In 1963, based upon recommendations of the conferees, the
Project began detailed studies of the mineral quality
problem in the Colorado River Basin. Mineral quality,
commonly known as salinity, is a complex Basinwide problem
that is becoming increasingly important to users of Colorado
River water. Due to the nature, extent, and impact of the
salinity problem, the Project extended certain of its
activities over the entire Colorado River Basin and the
Southern California water service area.
The more significant findings and data from the Project's
salinity studies and related pertinent information are
summarized in the report entitled, "The Mineral Quality
Problem in the Colorado River Basin." Detailed information
pertaining to the methodology and findings of the Project's
salinity studies are presented in three appendices to that
report—Appendix A, "Natural and Man-Made Conditions Affecting
Mineral Quality," Appendix B. "Physical and Economic Impacts,"
and Appendix C, "Salinity Control and Management Aspects."
ii
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TABLE OF CONTENTS
Page
PREFACE ii
LIST OF TABLES vi
LIST OF FIGURES vii
Chapter
I. INTRODUCTION 1
STATEMENT OF PROBLEM 1
STUDY OBJECTIVES 1
SCOPE 2
AUTHORITY. 3
II. SUMMARY OF FINDINGS AND RECOMMENDATIONS. 5
SUMMARY OF FINDINGS 5
RECOMMENDATIONS 8
III. DESCRIPTION OF AREA 9
PHYSICAL DESCRIPTION 9
CLIMATE 9
POPULATION AND ECONOMY 11
WATER RESOURCES . 12
WATER COMPACTS 12
WATER USE 13
IV. MINERAL QUALITY EVALUATION 14
CAUSES OF SALINITY INCREASES 14
SOURCES OF SALT LOADS . 17
PRESENT AND FUTURE SALINITY
CONCENTRATIONS 18
ill
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Page
PHYSICAL AND ECONOMIC IMPACT OF
SALINITY 24
Effects of Salinity on Beneficial
Uses of Water 24
Direct Economic Effects Upon Water
Users 26
Indirect Economic Effects 28
Total Penalty Costs 28
Total Salinity Detriments 30
V. TECHNICAL POSSIBILITIES FOR SALINITY
CONTROL 33
VI. SALINITY CONTROL ACTIVITIES 35
TECHNICAL INVESTIGATIONS 35
RESEARCH AND DEMONSTRATION
ACTIVITIES 36
SALINITY CONTROL PROJECTS 38
VII. ALTERNATIVES FOR MANAGEMENT AND CONTROL
OF SALINITY , 40
POTENTIAL ALTERNATIVE BASINWIDE
SALINITY CONTROL PROGRAMS 40
SALINITY MANAGEMENT COSTS 43
TOTAL SALINITY COSTS 46
ECONOMIC AND WATER QUALITY EFFECTS.... 46
COST DISTRIBUTIONS AND EQUITY
CONSIDERATIONS 50
LEGAL AND INSTITUTIONAL CONSTRAINTS... 53
OTHER CONSIDERATIONS 56
VIII. ACTION PLAN FOR SALINITY CONTROL AND
MANAGEMENT 57
BASIC WATER QUALITY OBJECTIVE 57
SALINITY STANDARDS 57
SALINITY CONTROL AGENCY 59
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Page
BASINWIDE SALINITY CONTROL PROGRAM 60
Legislative Authorization 61
Planning Phase 61
System Analyses 62
Research and Demonstration
Activities 63
Reconnaissance Investigations 64
Feasibility Studies 64
Legal and Institutional
Evaluations 65
Implementation Phase 65
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LIST OF TABLES
Table Page
1 Effect of Various Factors on Salt
Concentrations of Colorado River at
Hoover Dam (1960 Conditions) 15
2 Summary of Salt Load Distributions....... 18
3 Comparison of Salinity Projections 21
4 Effect of Various Factors on Future Salt
Concentrations of Colorado River at
Hoover Dam (2010 Conditions) 22
5 Summary of Penalty Costs 29
6 Technical Possibilities for Salinity
Control 33
7 Comparison of Alternative Salinity
Control Programs 42
8 Salinity Management Project Data 44
9 Comparison of Salinity Cost
Distributions 54
VI.
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LIST OF FIGURES
Figure Page
1 Colorado River Basin and Southern
California Water Service Area 10
2 Flow, Loads, and Salinity Concentrations
in Streams in the Colorado River Basin... 20
3 Location of Salinity Impact Study Area... 25
4 Salinity Detriments 31
5 Location of Potential Salt Load
Reduction Projects 45
6 Salinity Management Costs 47
7 Total Salinity Costs 48
8 Salinity Costs vs Time 51
9 Salinity Concentrations vs Time. 52
VI1
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CHAPTER I. INTRODUCTION
STATEMENT OF PROBLEM
The Colorado River system carries a large salt burden
(dissolved solids) contributed by a variety of natural and
man-made sources. Depletion of streamflow by natural
evapotranspiration and by comsumptive use of water for
municipal, industrial, and agricultural uses reduces the
volume of water available for dilution of this salt burden.
As a result, salinity concentrations in the lower river
system exceed desirable levels and are approaching critical
levels for some water uses. Future water resource and
economic developments will increase streamflow depletions
and add salt which in turn will result in higher salinity
concentrations.
As salinity concentrations increase, adverse physical
effects are produced on some water uses. These effects
result in direct economic losses to water users and indirect
economic losses to the regional economy. Unless salinity
controls are implemented, future increases in salinity
concentrations will seriously affect water use patterns and
will result in large economic losses.
STUDY OBJECTIVES
The objectives of the salinity investigations summarized
in this report were to provide answers to the following
questions:
What are the nature and magnitude of the major causes
of the salinity build-up in the Colorado River and its
tributaries?
What future changes in salinity concentrations may be
expected if no controls are implemented?
What are the present physical and economic impacts of
salinity on water uses, and how will these change in
the future?
What measures may be feasible for control and management
of salinity in the Colorado River system?
What are the economic costs and benefits associated
with various levels of salinity control?
What is the most practical approach to basinwide control
and management of salinity?
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What action must be taken to implement a basinwide
salinity control and management program?
SCOPE
The Colorado River Basin Water Quality Control Project
(hereinafter referred to as the Project) was established
in 1960 by the Division of Water Supply and Pollution
Control, U. S. Public Health Service (predecessor to the
Federal Water Quality Administration). The Project was
charged with the responsibility for identifying and
evaluating the most critical water pollution problems in
the Basin. Initial emphasis was placed upon evaluation and
control of pollution resulting from uranium mill operations.
As a result of early Project investigations, salinity was
identified as a pressing water quality problem which
warranted detailed study. In 1963, the Project initiated
salinity investigations directed toward answering the
questions outlined above. This report summarizes the results
of those investigations.
Salt sources contributing to the salinity problem are
located throughout the Colorado River Basin. A large
volume of water is exported from the Lower Colorado River
to areas of Southern California. For these reasons, the
geographical area covered by the Project included the
entire Colorado River Basin and the Southern California
water service area. Colorado River water is also utilized
by Mexico. However, investigation of the effects of salinity
on Mexican water uses was not within the scope of this
study.
A broad range of studies was carried out which involved an
array of scientific disciplines including hydrology, chemistry,
mathematics, computer science, soil science, geology, civil,
sanitary and agricultural engineering, and economics. The
Project studies included intensive, short-term water quality
field investigations, long-term water quality monitoring,
mathematical simulation of water quality relationships,
reconnaissance level evaluation of specific salinity control
measures, and detailed economic studies. In addition to the
Project's efforts in these areas, much input was provided
by other Federal and State agencies and institutions, some
of which were financially supported by the Federal Water
Quality Administration (FWQA).
The data and recommendations contained herein are specifically
related to the Colorado River Basin. However, the basic
approach and methodology developed for evaluation of the
physical and economic effects of salinity are considered
applicable to many other areas of the West. Salinity
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control measures developed for the Basin may also be
applicable to other areas with similar conditions.
It cannot be emphasized too strongly that if this report
has erred in regard to estimated projections of salinity
increases with the associated economic losses therefore,
the errors have been in the direction of minimizing
adverse effects. The actual effects are likely to be
more severe than these figures indicate.
AUTHORITY
The Federal Water Quality Administration, U. S. Department
of the Interior, formerly the Federal Water Pollution
Control Administration, has primary responsibility for
implementing national policy for enhancement of the quality
of the Nation's water resources through the control of
pollution. This policy has been spelled out over the past
14 years in a series of legislative acts which are described
as the Federal Water Pollution Control Act, as amended
(33 U.S.C. 466 et seq.). Section 10(d) of this Act
authorizes the Secretary of the Interior, ... "whenever
requested by any State water pollution control agency..."
if such request refers to pollution of waters which is
endangering the health or welfare of persons in a State
other than in which (the source of pollution) originates,
..."to call a conference..." of the State or States which
may be adversely affected by such pollution." Section 10
authorizes the Secretary to recommend "necessary remedial
action" and also provides various legal steps that may be
taken to abate pollution if remedial action is not taken
in a reasonable period of time.
Under the provision of Section 10 of the Act, the initial
session of the "Conference in the Matter of Pollution of
the Interstate Waters of the Colorado River and Its
Tributaries" was held on January 13, 1960. The conference
was requested by six of the seven Basin States. Five
additional formal sessions of the conference and three
technical sessions were held from 1960 to 1967. These
sessions provided assignments to the Project for developing
recommendations of remedial action to abate pollution.
Added impetus was given to the Project's salinity invest-
igations on October 2, 1965 by passage of the Water Quality
Act of 1965 (P.L. 89-234). This Act amended Section 10 of
the Federal Water Pollution Control Act to provide that
the States establish water quality standards for all
interstate waters. Subsequent difficulties, encountered
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in establishing suitable salinity criteria as a part of
these standards, pointed out the need to complete various
aspects of the Project's investigations in order to provide
the basis for establishing such standards.
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CHAPTER II. SUMMARY OF FINDINGS AND RECOMMENDATIONS
SUMMARY OF FINDINGS
1. Salinity (total dissolved solids) is the most serious
water quality problem in the Colorado River Basin.
Average annual salinity concentrations in the Colorado
River presently range from less than 50 mg/1 in the
high mountain headwaters to about 865 mg/1 at Imperial
Dam, the last point of major water diversion in the
United States. Salinity adversely affects the water
supply for a population exceeding 10 million people
and for 800,000 irrigated acres located in the Lower
Colorado River Basin and the Southern California water
service area. Salinity also adversely affects water
uses in Mexico and in limited areas of the Upper
Colorado River Basin.
2. Salinity concentrations in the Colorado River system are
affected by two basic processes: (1) salt loading, the
addition of mineral salts from various natural and man-
made sources, and (2) salt concentrating, the loss of
water from the system through evaporation, transpiration,
and out-of-basin export.
3. Salinity and stream flow data for the 1942-1961 period
of hydrologic record were used as the basis for estimating
average salinity concentrations under various conditions
of water development and use. Assuming repetition of
this hydrologic record, salinity concentrations at
Hoover Dam would average about 700 mg/1 and 760 mg/1
under 1960 and 1970 conditions. If development and
utilization of the Basin's water resources proceed as
proposed and if no salinity controls are implemented,
average annual salinity concentrations at Hoover Dam
would increase to about 880 mg/1 in 1980 and 990 mg/1 in
2010. Comparable figures at Imperial Dam are 760 mg/1
and 870 mg/1 under 1960 and 1970 conditions, and 1060
mg/1 and 1220 mg/1 under 1980 and 2010 conditions. If
future water resource development in the Basin were to
be limited to completion of projects currently under
construction, it is estimated that average annual salinity
concentrations for 1980 and subsequent years would
increase to only about 800 mg/1 at Hoover Dam and 920
mg/1 at Imperial Dam.
4. It is estimated that if the 1942-1961 period of hydrologic
record were repeated under conditions comparable to
when the Colorado River was in its natural state,
salinity concentrations at the site of Hoover Dam would
average about 330 mg/1. Because of man's influence,
average concentrations at this point more than doubled
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(697 mg/1) under 1960 conditions and will triple by
2010 (990 mg/1), if presently planned development and
utilization of water resources occurs. Reservoir
evaporation and irrigation will account for almost three-
fourths of the salinity increase between 1960 and 2010.
5. Under 1960 conditions, natural sources accounted for
47% of the salinity concentrations at Hoover Dam. The
remainder was accounted for by irrigation (37%), reservoir
evaporation (12%), out-of-basin exports (3%), and
municipal-industrial uses (1%) .
6. As salinity concentrations rise about 500 to 700 mg/1,
the net economic return from irrigated agriculture
begins to decrease because of increased operating costs
and reduced crop yields. At levels above 1,000 mg/1,
the types of irrigated crops grown may be limited, and
more intensive management of irrigation practices is
necessary to maintain crop yields. At levels exceeding
2,000 mg/1, only certain crops can be produced by adopting
highly specialized and costly irrigation management
practices. Municipal and industrial water users incur
increasing costs as salinity levels increase above 500
mg/1, the maximum level recommended in the U. S. Public
Health Service Drinking Water Standards.
7. The present annual economic detriments of salinity are
estimated to total $16 million. If water resources
development proceeds as proposed and no salinity controls
are implemented, it is estimated that average annual
economic detriments (1970 dollars) would increase to
$28 million in 1980 and $51 million in 2010. If future
water resources development is limited to those projects
now under construction, estimated annual economic
detriments would increase to $21 million in 1980 and
$29 million in 2010. Detriments to water users in
Mexico and to recreation and fishery users in the Salton
Sea are not included in the estimates.
8. More than 80 percent of the total future economic
detriments caused by salinity will be incurred by
irrigated agriculture located in the Lower Basin and the
Southern California water service area and by the
associated regional economy. About two-thirds of these
detriments will be incurred directly by irrigation water
users and the remainder will be incurred indirectly by
other industries associated with agriculture.
9. Alternatives for salinity control in the Colorado River
Basin include:
a. Augmentation of Basin water supply. This could be
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achieved by importation of demineralized sea water,
importation of fresh water from other basins, or
utilization of weather modification techniques to
increase precipitation and runoff. This alternative
should be considered as a possible long-term solution
to the salinity problem.
k- Reduction of salt loads. This could be achieved by
impoundment and evaporation of saline water from
point sources, diversion of runoff and streams
around areas of high salt pickup, improvement of
irrigation and drainage practices, improvement of
irrigation conveyance facilities, desalination of
saline discharges from natural and man-made sources,
and desalination of water supplies at points of use
with appropriate disposal of the waste brine. A
basinwide salt load reduction program has been
developed which would reduce the salt load contributed
by five large natural sources and twelve irrigated
areas totaling 600,000 acres. If fully implemented,
it is estimated that this program would reduce
average salinity concentrations at Hoover Dam by
about 250 mg/1 in 1980 and about 275 mg/1 in 2010.
c. Limitation of further depletion of Basin water supply.
This could be achieved by curtailment of future water
resources development. Such action would minimize
both future increases in salinity levels and the
adverse economic impact of such increases.
10. A basinwide salt load reduction program appears to be the
most feasible of the three salinity control alternatives.
The scope of such a program will depend upon the desired
salinity objectives. Partial implementation of the other
two alternatives would increase the effectiveness of the
salt load reduction program.
11. A basinwide salt load reduction program designed to
minimize total salinity costs (detriments plus control
costs) would have an estimated average annual cost
of $7 million in 1980 and $13 million in 2010 (1970
dollars). Implementation of this program could limit
salinity concentrations at Hoover Dam to approximately
1970 levels while allowing planned water resource
development to proceed. The direct salinity control
benefits (avoidance or mitigation of expected future
salinity detriments) of such a program are estimated
to total $11 million in 1980 and $22 million in 2010
(1970 dollars).
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RECOMMENDATIONS
It is recommended that:
A salinity policy be adopted for the Colorado
River system that would have as its objective the
maintenance of salinity concentrations at or
below levels presently found in the lower main-
stem.
Specific water quality standards criteria be
adopted at key points throughout the basin by
the appropriate States, in accordance with the
Federal Water Pollution Control Act. Such criteria
should be consistent with the salinity policy and
should assure the objective of keeping the
maximum mean monthly salinity concentrations at
Imperial Dam below 1000 mg/1. These criteria
should be adopted by January 1, 1973.
Implementation of the recommended policy and
criteria be accomplished by carrying out a basin-
wide salinity control program concurrently with
planned future development of the basin's water
resources.
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CHAPTER III. DESCRIPTION OF AREA
PHYSICAL DESCRIPTION
The Colorado River is situated in the southwestern United
States and extends 1,400 miles from the Continental Divide
in the Rocky Mountains of north central Colorado to the
Gulf of California (Figure 1). Its river basin covers
an area of 244,000 square miles, approximately one-twelfth
of the continental United States. The Colorado River Basin
includes parts of seven states; Arizona, California,
Colorado, Nevada, New Mexico, Utah and Wyoming. About one
percent of the Basin drains lands in Mexico.
The Colorado River rises on the east slope of Mount
Richthofen, a peak on the Continental Divide having an
altitude of 13,000 feet, and flows generally southwestward,
leaving the United States at an elevation of about 100 feet
above sea level. The Colorado River Basin is composed of
a complex of rugged mountains, high plateaus, deep canyons,
deserts and plains. Principal physical characteristics of
the region are its variety of land forms, topography and
geology.
The Colorado River Compact of 1922 established a division
point on the Colorado River at Lee Ferry, Arizona, to
separate the Colorado River Basin into an "Upper Basin"
and a "Lower Basin" for legal, political, institutional and
hydrologic purposes. Lee Ferry is located about one mile
below the confluence of the Paria River and approximately 17
miles downstream from Glen Canyon Dam. The Upper Basin
encompasses about 45 percent of the drainage area of the
Colorado River Basin.
In addition to the Colorado River Basin, the Project's
investigations covered the area of southern California
receiving Colorado River water. This area of about 15,400
square miles includes the Imperial and Coachella Valleys
which surround the Salton Sea as well as the metropolitan
areas of Los Angeles and San Diego.
CLIMATE
Climatic extremes in the Basin range from hot and arid in
the desert areas to cold and humid in the mountain ranges.
Precipitation is largely controlled by elevation and the
orographic effects of mountain ranges. At low elevations
or in the rain shadow of coastal mountain ranges, desert
areas may receive as little as 6 inches of precipitation
annually, while high mountain areas may receive more than
60 inches.
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-*••-••
LEGEND
—— Colorado River Basin Boundary
Southern California Water Service Area Boundary
Figure 1 Colorado River Basin and Southern California Water Service Area
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Basin temperatures range from temperate, affording only a
90-day growing season in the mountain meadows of Colorado
and Wyoming, to semi-tropical with year-round cropping in
the Yuma-Phoenix area. On a given day, both the high and
low temperature extremes for the continental United States
frequently occur within the Basin.
In the southern California water service area, the climate
of the area surrounding the Salton Sea is hot and arid, while
the climate of the coastal metropolitan areas is moderated
by proximity to the Pacific Ocean.
POPULATION AND ECONOMY
The Colorado River Basin is sparsely populated. In 1965 the
estimated population was nearly 2.25 million. The average
density was about nine persons per square mile compared with
a national average of 64. Eighty-five percent of the
population lived in the Lower Basin. About 70 percent of the
Lower Basin population resided in the metropolitan areas
of Las Vegas, Nevada, and Phoenix and Tucson, Arizona. The
population of the Colorado River Basin is estimated to
triple by 2010.
The southern California water service area contained an
estimated eleven million people in 1965. Most of the
population was concentrated in the highly urbanized
Los Angeles-San Diego metropolitan area.
The economy of the Basin is based on manufacturing, irrigated
agriculture, mining, forestry, oil and gas production,
livestock and tourism.
The present economy of the Upper Basin is largely resource
oriented. This orientation is not restricted entirely to
agriculture, forestry and mining, but includes the region's
recreational endowment and the associated contribution to
basic income. The mineral industry overshadows activities
of the agricultural and forestry sectors. The major effects
of outdoor recreation and tourism are reflected in the
tertiary or non-commodity producing industries which as a
group contribute the greatest share to total Upper Basin
economic activity.
In the last two decades, the economy of the Lower Basin has
experienced a significant transition from an agricultural-
mining base to a manufacturing-service base. Growth in the
manufacturing sectors has been one of the major factors in
the overall economic growth of the Lower Basin. Important
manufacturing categories are electrical equipment, aircraft
and parts, primary metals industries, food and kindred
products, printing and publishing, and chemicals.
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Agriculture continues to play an important role in the
southern California economy amidst the fast-growing industrial
and commercial activity. Manufacturing is the most important
industrial activity and principally includes production of
transportation equipment (largely aircraft and parts),
machinery, food and kindred products, and apparel. Agri-
culture accounts for about three percent of the total
employment, manufacturing for an estimated 30 percent, and
trades and services for approximately 42 percent.
WATER RESOURCES
An average of about 200 million acre-feet of water a year
is provided by precipitation in the Colorado River Basin.
All but about 18 million acre-feet of this is returned to
the atmosphere by evapotranspiration. Most of the streamflows
originate in the high forest areas where heavy snowpacks
accumulate and evapotranspiration is low. A small amount of
runoff originates at the lower altitudes, primarily from
infrequent storms. Approximately two-thirds of the runoff
is produced from about six percent of the Basin area.
Streamflows fluctuate widely from year to year and season to
season because of variations in precipitation, and numerous
reservoirs have been constructed to make water available
for local needs, exports and downstream obligations. The
usable capacity of the Basin reservoirs is about 62 million
acre-feet.
WATER COMPACTS
In addition to State laws which provide for intrastate control
of water, use of water in the Colorado River system is
governed principally by four documents—the Colorado River
Compact signed in 1922, the Mexican Water Treaty signed in
1944, the Upper Colorado River Basin Compact signed in 1948
and by the Supreme Court Decree of 1964 in Arizona vs.
California.
Among other provisions, the Colorado River Compact apportions
to each the Upper and Lower Basin in perpetuity the
exclusive beneficial consumptive use of 7,500,000 acre-feet
of water of the Colorado River system per annum. It
further establishes the obligation of Colorado, New Mexico,
Utah, and Wyoming, designated States of the Upper Division,
not to cause the flow of the river at Lee Ferry to be
depleted below an aggregate of 75 million acre-feet for
any period of 10 consecutive years.
The Mexican Water Treaty defines the rights of Mexico to
the use of water from the Colorado River system. It
guarantees the delivery of 1,500,000 acre-feet of Colorado
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River water annually from the United States to Mexico.
In accordance with the Upper Colorado River Basin Compact,
Arizona is granted the consumptive use of 50,000 acre-feet
of water a year and the other Upper Basin States are each
apportioned a percentage of the remaining consumptive use
as follows: Colorado 51.75 percent, New Mexico 11.25
percent, Utah 23 percent, and Wyoming 14 percent. Of the
first 7,500,000 acre-feet annually of Colorado River water
entering the Lower Basin, the States of Arizona and Nevada
are apportioned 2,800,000 acre-feet and 300,000 acre-feet
respectively. The Lower Division apportionment was divided
among the Lower Basin States—Arizona, California, and
Nevada—by the decree of the United States Supreme Court
in 1964 which states that apportionment was accomplished
by the Boulder Canyon Project Act of 1929. If Colorado
River mainstem water is available in sufficient quantity
to satisfy 7,500,000 acre-feet of annual consumptive use
in the three Lower Basin states, Arizona, Nevada, and
California are apportioned 2,800,000, 300,000 and
4,400,000 acre-feet, respectively.
WATER USE
There is essentially no outflow from the Basin beyond that
required to meet the Mexican Treaty obligation. In 1965,
one-half million acre-feet of water was exported out of the
Upper Basin for use in other parts of the Upper Basin States.
Gross diversions from the Lower Colorado River for use in the
southern California service area and the Lower Colorado area
in California totaled 5.35 million acre-feet in 1965.
The major use of water within the Basin is for agricultural,
municipal, and industrial purposes. At present, over 90
percent of the total Basin withdrawal from ground-water and
surface-water sources serves irrigated agriculture within
the basin. The remaining portion is used principally for
municipal and industrial uses. Approximately three-fourths
or 7.0 million acre feet of the water consumptively used in
the Basin each year is depleted by agricultural uses. Minor
quantities of water are consumed by hydroelectric and thermal
power production, recreation, fish and wildlife, rural-
domestic needs, and livestock uses. In the urban areas of
the Basin, municipal and industrial uses are increasing
significantly due to the rapid rate of population growth.
One of the largest causes of streamflow depletions in the
Basin is surface evaportation from storage reservoirs. Over
2.0 million acre-feet are estimated to evaporate annually
from the lakes and reservoirs of the Basin. Most of this
evaporates from major storage reservoirs on the main stem
of the Colorado River.
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CHAPTER IV. MINERAL QUALITY EVALUATIONS
At the outset of the Project only limited information was
available on the causes and sources of salinity in the
Colorado River Basin. Little was known about the economic
impact of salinity on water uses. No comprehensive
evaluation of projected future mineral quality had been
made. A major Project effort, therefore, was directed toward
improving knowledge in these specific areas. Results of
these investigations are summarized in the following sections.
CAUSES OF SALINITY INCREASES
Salinity concentrations progressively increase from the
headwaters to the mouth of the Colorado River. This increase
results from two basic processes - salt loading and salt
concentrating. Salt loading, the addition of mineral salts
from various natural and man-made sources, increases salinity
by increasing the total salt burden carried by the river. In
contrast, salt concentrating effects are produced by
streamflow depletions and increase salinity by concentrating
the salt burden in a lesser volume of water.
Salt loads are contributed to the river system by natural
and man-made sources. Natural sources include diffuse
sources such as surface runoff and diffuse ground water
discharges, and discrete sources such as mineral springs,
seeps, and other identifiable point discharges of saline
waters. Man-made sources include municipal and industrial
waste discharges and return flows from irrigated lands.
Streamflow depletions contribute significantly to salinity
increases. Consumptive use of water for irrigation is
responsible for the largest.depletions. Consumptive use of
water for municipal and industrial purposes accounts for
a much smaller depletion. Evaporation from reservoir and
stream surfaces also produces large depletions. Phreatophytes,
too, cause significant water losses by evapotranspiration,
especially in the Lower Basin below Hoover Dam.
Out-of-basin diversions from the Upper Basin contribute
significantly to streamflow depletions and produce a salt
concentrating effect similar to consumptive use. The water
diverted is high in quality and low in salt content. Thus,
while these diversions remove substantial quantities of
water from the Basin, they remove only a small portion of
the salt load.
The relative effects of the various salt loading and salt
concentrating factors on salinity concentrations of the
Colorado River at Hoover Dam are summarized in Table 1. This
evaluation indicates that about 74 percent of average
14
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salinity concentrations for the 20-year period 1942-1961
were attributable to salt loading factors. The remaining
26 percent were attributable to salt concentrating factors.
The relative effects of natural and man-made factors are also
summarized in Table 1. Only about 47 percent of average
salinity concentrations for the 20-year period were attributed
to natural factors. This evaluation indicates that salinity
concentrations would have averaged only 334 mg/1 at the
Hoover Dam location under natural conditions for the 1942-1961
period.
A more detailed discussion of the various factors affecting
salt concentrations is contained in Appendix A.
SOURCES OF SALT LOADS
Natural sources, including both diffuse and discrete sources,
are the most important sources of salt loads in the Colorado
River Basin. They contribute about two-thirds of the average
annual salt load passing Hoover Dam. Natural diffuse
pickup of mineral salts by surface runoff and groundwater
inflow takes place throughout the Colorado River Basin;
however, the areas responsible for the greatest salt loads
are located in the Upper Basin. Several relatively small
areas, such as Paradox Valley, have very high rates of
pickup and contribute large salt loads. Diffuse sources
contribute about half of the Basin salt burden.
Discrete or point salinity sources also occur throughout
the Basin. In the Lower Basin, mineral springs add more
salt to the Colorado River than any other type of salinity
source. Blue Springs, located near the mouth of the
Little Colorado River, contributes a salt load of about
547,000 tons per year, or approximately five percent of the
annual salt burden at Hoover Dam. Blue Springs is the
largest point source of salinity in the entire Colorado
River Basin. In the Upper Basin, some 30 significant
mineral springs have been identified. Dotsero and Glenwood
Springs, two major point sources of salinity, contribute
a salt load of about 518,000 tons per year.
Man's use of water for irrigation, municipal, and industrial
purposes contributes to salt loading effects. Irrigation
is the major man-made source of salinity throughout the
Basin. The annual salt pickup from all irrigation above
Hoover Dam averages about two tons per acre. For some
areas, especially those underlain by shales and saline
lake-bed formations, salt pickup is much higher, with
average annual loads ranging between four and eight tons
per acre. Below Hoover Dam, the average annual salt pickup
from irrigation is about 0.5 ton per acre after the initial
leaching period.
17
-------
Municipal and industrial salinity sources located within
the drainage area of Lake Mead contribute only about one
percent of the average annual salt load at Hoover Dam.
Below Hoover Dam, these sources are responsible for less
than one percent of the average annual salt load.
The sources and amounts of salt loads for the Upper Basin,
the Lower Basin, and the drainage area of Lake Mead above
Hoover Dam are summarized in Table 2. Data presented in
Table is based on salinity conditions existing in the
period 1963-1966 and should not be confused with data in
Table 1 which is based on period 1942-61. The Upper Basin
sources contribute approximately 77 percent of the salt
load at Hoover Dam, about three-fourths of total Basin salt
load.
A detailed discussion of the nature, location, and magnitude
of salt sources in the Basin is contained in Appendix A.
Table 2. Summary of Salt Load Distributions
Salt Load (1,000) T/Yr. Percent of Total Load
Upper Lower Above Upper Lower Above
Source Basin Basin Hoover Dam Basin Basin Hoover Dam
Natural Diffuse
Sources 4,400 1,400 5,760 52.2 52.1 53.7
Natural Point
Sources 510 770 1,280 6.1 28.6 11.9
Irrigation 3,460 420 3,540 41.1 15.6 33.0
Municipal and
Industrial 50_ 100 150 0.6 3.7
Total 8,420 2,690 10,730 100.0 100.0
PRESENT AND FUTURE SALINITY CONCENTRATIONS
Lpng-term average salinity levels have progressively increased
in the Colorado River system as the Basin's water resources
have been developed and consumptive use of water for yarious
purposes has increased. This trend is expected to continue
with future water resource development and to bring about
serious water quality implications. As the economic impact
of salinity is closely related to the rate at which salinity
levels rise in the future, an evaluation was made of present
and future salinity concentrations in the Basin to provide
the basis for the economic evaluation discussed in the
following section. Historical salinity and stream flow data
for the 1942-1961 period of hydrologic record were used as the
basis for estimating average salinity concentrations under
18
-------
various conditions of water development and use. This
historical data was modified to reflect the effects that
water uses existing in 1960 would have' had on average
salinity levels if these uses had existed during the full
20-year period. Average salinity concentrations obtained
from this modified data were designated as 1960 base
conditions. These concentrations are shown at key Basin
locations in Figure 2.
Predicted future conditions of water use, based on Federal,
State and local development plans available in 1967, were
utilized to develop detailed projections of 1980 and 2010
salinity levels. These projections based on the assumptions
that water resource development would proceed as planned in
1967 and that the 1942-1961 hydrologic record would be
repeated, are shown at key Basin locations in Figure 2.
These projections are for long-term average salinity
concentrations; actual concentrations can be expected to
fluctuate about these averages as a result of seasonal
changes in streamflow and other hydrological factors.
Sensitivity of future salinity projections to the period
of record utilized and the assumptions concerning the rate
of water resaurce development are discussed in Appendix C.
To provide the degree of refinement necessary to allow
evaluation of the small incremental changes in salinity
levels produced by a given water resource development,
salinity concentrations were computed to the nearest mg/1
in making the projections shown in Figure 2. It was not
intended that a high degree of accuracy by implied as
salinity projections are dependent upon a number of factors
which are not known with certainty.
The detailed salinity projections presented in Figure 2
were made on the basis that no limits would be placed on
future water resource developments other than those limits
imposed by availability of a water supply under applicable
water laws. In evaluating potential means of managing
salinity on a basinwide basis as discussed in Chapter VII,
it became apparent that one possible approach to management
of future salinity levels would be to limit further water
resource development in the Basin. A second set of salinity
projections was made to evaluate the results of limiting
such development. A/comparison of future salinity levels
at four key locations on the Lower Colorado River for
unlimited and limited development conditions is shown in
Table 3.
19
-------
IMPERIAL DAM. ARIZ -CALIF
9971
6171
6103
9272
7274
8180
684
866
983
LEtENO
F low Soil Load Conon-
.I.OOO (1.000 tration
arget Y e ar Ac-Ft/Yt Toos/Yr) (mo/I)
1960
1980
2010
NOTE : Values shin ire based n 1S42 - 19(1 leriid if recird modified to DID cuditioiis.
Figure 2. Flow, Loads, & Salinity Coocrntrations in Streams in the Colorado River Basin
-------
Table 3. Comparison of Salinity Projections
Unlimited Development
Conditions
Location
Hoover Dam
Parker Dam
Palo Verde Dam
Imperial Dam
1960
Base
697
684
713
759
1980
876
866
940
1056
2010
990
985
1082
1223
Limited Development
Conditions
1970 1980 & 2010
760 800
760 800
800 850
865 920
Salinity projections for 1970 conditions of limited develop-
ment were made on the basis that water resource developments
currently in operation and present water use patterns would
hold for a repetition of the 1942-1961 hydrological record.
The 1970 projections reflect the effects of evaporation
losses from Lake Powell operated at normal levels. Since
Lake Powell has not yet reached normal storage levels,
evaporation losses are less than expected average losses and
present average salinity levels at downstream points are
correspondingly lower than projected.
For 1980 conditions of limited development, it was assumed
that no new water resource developments would be placed in
operation but that those projects currently under construction
would be completed as planned. It was assumed that all such
construction could be completed by 1980 and that 2010 con-
ditions of water use would remain the same as for 1980.
In the past, salt loading was the dominant factor affecting
salinity concentrations, contributing about three-fourths
of average salinity concentrations at Hoover Dam under 1960
conditions. In contrast, future increases in salinity
levels will result primarily from flow depletions caused by
out-of-basin exports, reservoir evaporation and consumptive
use of water for municipal, industrial and agricultural
purposes. The relative effects of these factors on future
salinity concentrations at Hoover Dam are summarized in
Table 4.
Projections for Hoover Dam indicate a relatively constant,
average salt load over the next 40 years, but a substantial
drop in water flow. Over 80 percent of the future increase
in salinity concentrations at Hoover Dam will be the result
of increases in flow depletions. Over three-fourths of the
projected salinity increase between 1960 and 2010 will be
the result of increases in reservoir evaporation brought
about by the filling of major storage reservoirs completed
since 1960 and of increases in consumptive use brought about
by the expansion of irrigated agriculture.
21
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PHYSICAL AND ECONOMIC IMPACT OF SALINITY
Water uses exhibit an increasing sensitivity to rising
salinity concentrations. As concentrations of salinity
rise water use is progressively impaired, and at some
critical level, defined as a threshold level, utilization
of the supply is no longer possible. In the Colorado River
Basin, future salinity concentrations will be below threshold
levels for in stream uses such as recreation, hydroelectric
power generation, and propagation of aquatic life. Only
marginal impairment of these uses is anticipated.
In the Lower Colorado River present salinity concentrations
are above threshold limits for municipal, industrial and
agricultural uses. Some impairment of these uses is now
occurring and future increases in salinity will increase this
adverse impact. The Projects investigated this progressive
impairment of water uses and developed methods to quantify
the resulting economic impact on both water users and the
regional economy. It should be emphasized that the
methodology employed by the Project staff was intentionally
conservative; all costs developed by this report to describe
the impact of salinity must be considered minimal values.
Initial investigations conducted on the potential impact of
future salinity levels revealed that only small effects on
water uses could be anticipated in the Upper Basin.
Subsequent investigations, therefore, were limited to three
main study areas: the Lower Main Stem and Gila areas in
the Lower Basin, and the Southern California area encompass-
ing the southern California water service area. The
boundaries of these study areas follow political rather
than hydrological boundaries and are shown in Figure 3.
Although significant economic effects are known to occur in
Mexico, lack of data precluded their inclusion.
Effects of Salinity on Beneficial Uses of Water
Initial evaluations of possible salinity effects on Basin
water uses indicated that adverse physical effects would
essentially be limited to municipal, industrial, and
agricultural uses. Major effects on these uses are discussed
briefly in this section.
Domestic uses comprise the major utilization of municipal
water supplies. Total hardness, a parameter closely
related to salinity, is of primary interest in assessing
water quality effects on these uses. Increases in the
concentration of hardness lead to added soap and detergent
24
-------
IIECON
IOAHI
WVINING
NEVAIA
CALIFORNIA
NEW MEXICO
LEfiEM
SUIT 11(1 IHNIIIT
MSI* loumtir
SHU
COIIKH
Figure 3. Location of Salinity Impact Study Areas
-------
consumption, corrosion and scaling of metal water pipes and
water heaters, accelerated fabric wear, added water softening
costs, and in extreme cases, abandonment of a supply. By
most hardness measures, raw water supplies derived from the
Colorado River at or below Lake Mead would be classified as
very hard.
Boiler feed and cooling water comprise a major portion of
water used by industry in the Basin. Mineral quality of
boiler feed water is an important factor in the rate of
scale formation on heating surfaces, degree of corrosion in
the system, and quality of produced steam. In cooling water
systems, resistance to slime formation and corrosion are
effected by mineral quality. The required mineral quality
levels are maintained in boiler and cooling systems by
periodically adding an amount of relatively good quality
water (make-up water) and discharging from the system an
equal volume of the poorer quality water (blowdown).
Salinity effects on agricultural uses are manifested
primarily by limitations on the types of crops that may be
irrigated with a given water supply and by reductions of
crop yields as salinity levels increase. Other conditions
being equal, as salinity levels increase in applied irrigation
water, salinity levels in the root zone of the soil also
increase.
Because different crops have different tolerances to salts
in the root zone, limits are placed on the types of crops
that may be grown. When salinity levels in the soil
increase above the threshold levels of a crop, progressive
impairment of the crop yield results. Irrigation water
which has a high percentage of sodium ions may also affect
soil structure and cause adverse effects on crop production.
The primary means of combating detrimental salinity
concentrations in the soil are to switch to salt tolerant
crops or to apply more irrigation water and leach out excess
salts from the soil.
Direct Economic Effects Upon Water Users
The previously described physical impacts of salinity upon
consumptive uses of water were translated into economic
values by evaluating how each user might alleviate the
effects of salinity increases. Municipalities could (1)
do nothing and the residents would consume more soap and
detergents or purchase home softening units; (2) build
central water softening plants; or (3) develop new, less
mineralized water supplies. Industrial users could combine
more extensive treatment of their water supply with the
purchase of additional make-up water based upon the
26
-------
economics of prevailing conditions. The alternatives
available to irrigation water users are governed by the
availability of additional water. (1) If the irrigator
does nothing, he will suffer economic loss from decreased
crop yields. (2) If additional water is available, root
zone salinity may be reduced by increasing leaching water
applications. The irrigator would incur increased costs
for purchase of water, for additional labor for water
application, and for increased application of fertilizer
to replace the fertilizer leached out. (3) If no additional
water is available, the irrigator can increase the leaching
of salts from the soil by applying the same amount of water
to lesser acreage. This, of course, results in an economic
loss since fewer crops can be grown. (4) The last alter-
native is to plant salt tolerant crops. An economic loss
would usually occur since salt tolerant crops primarily
produce a lower economic return.
The cost of applying each of the alternative remedial
actions was determined, and the least costly alternative
selected for subsequent analyses. The yield-decrement
method, which measures reductions in crop yield resulting
from salinity increases, was selected to evaluate the
economic impact on irrigated agriculture. For industrial
use, an estimate of required make-up water associated with
salinity increases was selected to calculate the penalty
cost. Municipal damages were estimated by calculating the
required additional soap and detergents needed. Details
of the methodology employed and a discussion of the
assumptions required to complete the analysis are presented
in Chapter IV of Appendix B.
The direct economic costs of mineral quality degradation may
be summarized in two basic forms, total direct costs and
penalty costs. Total direct costs incurred for a given
salinity level result from increases in salinity concent-
rations above the threshold levels of water uses. Penalty
costs are the differences between total direct costs for
a given salinity level and for a specified base level. They
represent the marginal costs of increases in salinity
concentrations above base conditions.
Detailed economic studies were aimed at evaluating penalty
costs in order to provide a basis for assessing the
economic impact of predicted future increases in salinity.
Water quality, water use patterns, and economic conditions
existing in 1960 were selected as base conditions. Water
use and economic conditions projected for the target years
1980 and 2010 and predictions of future salinity concent-
rations were utilized to estimate total direct costs in the
future. Direct penalty costs were then computed from
27
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differences in total direct costs. These direct penalty
costs are summarized by type of water use and by study area
in Table 5. The indirect and total penalty costs, also
presented in the table, are discussed below.
Indirect Economic Effects
Because of the interdependence of numerous economic
activities, there are indirect effects on the regional
economy stemming from the direct economic impact of salinity
upon water users. These effects, termed indirect penalty
costs, can be determined if the interdependency of economic
activities are known.
The Project's economic base study investigated the inter-
dependence of various categories of economic activity or
sectors. These interdependent relationships, in the form
of transactions tables, were quantified for 1960 conditions,
and were projected for the target years 1980 and 2010. A
digital computer program known as an "input-output model"
was developed to follow changes affecting any given industry
through a chain of transactions in order to identify secondary
or indirect effects on the economy stemming from the direct
economic costs of salinity. Application of the model to
evaluate indirect penalty costs is discussed in Appendix B,
Chapter V. The indirect penalty costs predicted by the
model are summarized in Table 5.
Total Penalty Costs
Total penalty costs represent the total marginal costs of
increases in salinity concentrations above base conditions.
They are the sum of direct penalty costs incurred by water
users and indirect penalty costs suffered by the regional
economy. Total penalty costs are also summarized in
Table 5.
Several conclusions can be drawn from Table 5.
1. The majority of the penalty costs (an average of 82
percent) will result from water use for irrigated
agriculture. This fact may be attributed to the heavy
utilization of Colorado River water for irrigation
along the Lower Colorado River and in the southern
California area.
2. Over three-fourths of the penalty costs will be incurred
in the southern California water service area. These
costs will result primarily from agricultural use in
the Imperial and Coachella Valleys, and municipal and
industrial uses in the coastal metropolitan areas.
28
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3. Penalty costs in the Gila study area will be minor and
will not occur until after 1980 when water deliveries
to the Central Arizona Project begin. (It was assumed
that all Central Arizona Project water would be utilized
for agricultural purposes.)
It should be noted that the penalty costs summarized in
Table 3 do not represent the total economic impact of salinity,
but only the incremental increases in salinity detriments
resulting from rising salinity levels. There are economic
costs known as salinity detriments that were being incurred
by water users in 1960 as a result of salinity levels
exceeding threshold levels for certain water uses. These
costs would continue in the future if salinity levels remained
at the 1960 base conditions. Total salinity detriments are
discussed below.
Total Salinity Detriments
The detailed economic analysis outlined in previous sections
and discussed in detail in Appendix B forms a basis for
evaluating the distribution of the total economic impact of
future salinity increases. Penalty costs are not practical,
however, for evaluation of the economic impact of basinwide
salinity control, especially when reductions in salinity
concentrations below 1960 base levels were considered. For
this reason, estimates of total salinity detriments were
prepared utilizing the basic information developed for
peanlty cost evaluations. These estimates, in the form of
empirical relationships between salinity levels at Hoover
Dam and salinity detriments, are shown graphically for
various target years in Figure 4.
Hoover Dam is a key point on the Colorado River system. Water
quality at most points of use in the Lower Basin and Southern
California water service area may be directly related to
salinity levels at Hoover Dam. Modifications of salt loads
contributed by sources located upstream from Hoover Dam also
directly affect salinity levels at this location. Salinity
concentrations at Hoover Dam were, therefore, utilized as a
water quality index to which all economic evaluations were
keyed.
Total salinity detriments are the sum of direct costs to
water users (including direct penalty costs) and indirect
penalty costs. A discussion of the methodology used to
develop the detriment relationships is contained in Appendix
C. It should be noted that the salinity detriments are
expressed in terms of 1970 dollars. It was necessary to
modify the basic data utilized in evaluating penalty costs
(expressed in terms of 1960 dollars) in order to make the
30
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5 30
600 700 800 900 1000 1100
TOTAL DISSOLVED SOLIDS CONCENTRATION MG/L AT HOOVER DAM
Figure 4. Salinity Detriments
-------
salinity detriments compatible with current estimates of
salinity management costs discussed in Chapter VII.
Using the projected salinity levels for Hoover Dam shown
in Table 3 and the salinity detriment functions of Figure
4, it is possible to compare the total economic detriments
of salinity under various conditions of water use and resource
development. Under 1960 conditions, the annual economic
impact of salinity was estimated to total $9.5 million. It
is estimated that present salinity detriments have increased
to an annual total of $15.5 million. If water resources
development proceeds as proposed and no salinity controls are
implemented, it is estimated that average annual economic
detriments (1970 dollars) would increase to $27.7 million
in 1980 and $50.5 million in 2010. If future water resources
development is limited to those projects now under construction,
estimated annual economic detriments would increase to
$21 million in 1980 and $29 million in 2010.
32
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CHAPTER V. TECHNICAL POSSIBILITIES FOR
SALINITY CONTROL
Technical possibilities for minimizing and controlling
salinity in the Colorado River Basin may be divided into
two categories: water-phase and salt-phase control measures.
Water-phase measures seek to reduce salinity concentrations
by augmenting the water supply, while salt-phase measures
seek to reduce salt input into the river system. Specific
control measures are listed in Table 6 and are discussed at
length in Appendix C, Chapter III.
Various factors, such as economic feasibility, lack of
research and legal and institutional constraints limit the
present application of some water-phase and salt-phase control
measures. The most practical means of augmenting the Basin
water supply include importing water from other basins,
importing demineralized sea water, and utilizing weather
modification techniques to increase precipitation and runoff
within the Basin. Practical means of reducing salt loads
include: impoundment and evaporation of point source
discharges, diversion of runoff and streams around areas of
salt pickup, improvement of irrigation and drainage practices,
improvement of irrigation conveyance facilities, desalination
of saline discharges from natural and man-made sources, and
desalination of water supplies at points of use. These
measures could be implemented in a variety of locations and
in several different combinations.
Table 6. Technical Possibilities for Salinity Control
I. Measures for Increasing Water Supply
A. Water Conservation Measures
1. Increased Watershed Runoff
2. Suppression of Evaporation
3. Phreatophyte Control
4. Optimized Water Utilization for Irrigation
a. Reduced Consumptive Use
b. Improved Irrigation Efficiency
5. Water Reuse
B. Water Augmentation Measures
1. Weather Modification
2. Water Importation
a. Fresh Water Sources
b. Demineralized Sea Water
33
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Table 6. Technical Possiblities for Salinity Control (con't)
II. Measures for Reducing Salt Loading
A. Control of Natural Sources
1. Natural Discrete Sources
a. Evaporation of Discharge
b. Injection into Deep Geological Formations
c. Desalination
d. Suppression of Discharge
e. Reduction of Recharge
2. Natural Diffuse Sources
a. Surface Diversions
b. Reduced Groundwater Recharge
c. Reduced Sediment Production
B. Control of Man-Made Sources
1. Municipal and Industrial Sources
a. Evaporation
b. Injection into Deep Geological Formations
c. Desalination
2. Irrigation Return Flows
a. Proper Land Selection
b. Canal Lining
c. Improved Irrigation Efficiency
d. Proper Drainage
e. Treatment or Disposal of Return Flows
34
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CHAPTER VI. SALINITY CONTROL ACTIVITIES
Activities related to the control and management of salinity
have been carried out over the years by a variety of agencies
and institutions and have contributed to the overall know-
ledge of salinity control technology. In the past four
years, several activities have been specifically directed
toward the application of salinity control technology to the
Colorado River Basin. The current status of these activities
is discussed in the following sections.
TECHNICAL INVESTIGATIONS
Limited investigations of several potential salinity control
projects and control measures were made by the Project.
These investigations evaluated a number of technical
possibilities for salinity control discussed in Chapter V.
Salinity control research needs were also identified; these
provided the basis for support by the FWQA of several research
efforts discussed below.
Early in FY 1968, the FWQA and the Bureau of Reclamation
initiated a cooperative salinity control reconnaissance study
in the Upper Basin. Study objectives were to identify
controllable sources of salinity and to determine technically
feasible control measures and estimate their costs. A
shortage of funds resulted in discontinuance of the study
during FY 1970. A report entitled "Cooperative Salinity
Control Reconnaissance Study, Upper Colorado River Basin,"
presenting the results of the study to date, is scheduled
for release during 1970.
During the course of the study, preliminary plans were
developed for two salinity control projects, and cost
estimates were prepared for a number of control measures.
(1) A project was formulated to eliminate the heavy pickup
of salt by the Dolores River as it crosses a salt anticline
in the Paradox Valley of western Colorado. Control of this
salt source could be achieved by constructing both a flood-
water retarding dam and a lined channel to convey the river
across the valley and prevent recharge of an aquifer in
contact with salt formations. (2) A project was also
formulated to control the salt load from Crystal Geyser, an
abandoned oil test well which periodically discharges highly
mineralized water. Control could be achieved by collecting
the discharge and pumping it to a lined impoundment for
evaporation. If suitable land area for an evaporation pond
could be found and evaporation rates were high enough, a
project of this type could be potentially applicable for
control of some of the more concentrated mineral springs.
35
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Cost estimates were prepared for several types of salinity
control measures, but preliminary plans were not developed
for specific sites. For control of irrigation return flows,
the costs of impounding and evaporating the flows at two
topographically different sites were estimated. The costs
of deep well injection of relatively small quantities of
the more concentrated return flows were also evaluated.
The cost of lining canals and distribution systems in
several existing irrigation projects was investigated.
Following discontinuance of the cooperative study, the
project conducted a preliminary study of a project to
control the salt load from several large mineral spring areas
in the vicinity of Glenwood Springs, Colorado.
A similar preliminary study of control measures for LaVerkin
Springs, a large thermal spring discharging significant
quantities of radium-226 and mineral salts into the Virgin
River of southern Utah, is currently underway.
RESEARCH AND DEMONSTRATION ACTIVITIES
A number of research and demonstration projects presently
underway are expected to contribute significantly to the
development and/or evaluation of various salinity control
measures.
(1) Under an FWQA research grant, a project entitled
"Quality of Irrigation Return Flow" was initiated during
FY 1969 by Utah State University at Logan, Utah. This
project is directed toward the dual objectives of increasing
the store of knowledge of basic processes controlling the
movement of salts in soils, and applying this knowledge to
development of salinity control measures. Research to date
has primarily been conducted on a small scale in the
laboratory and in greenhouse lysimeters. A digital simulation
model is being developed to accurately predict the movement
of salts and the changes in quality of applied irrigation
water within the soil and root zone. This model will be
utilized to design on-farm irrigation practices, such as the
rate and timing of irrigation applications, which will
minimize the salt load contributed by irrigation activities.
The University has established a 40-acre test farm in Ashley
Valley near Vernal, Utah, and will conduct full scale field
testing of theoretical results during 1970 and 1971.
Establishment of a test farm at this location will provide
a demonstration of salinity control measures under conditions
similar to those found in many irrigated areas of the Upper
Basin.
36
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(2) In response to a request from the FWQA, a large scale
research project entitled "Prediction of Mineral Quality of
Return Flow Water from Irrigated Land" was initiated by the
Bureau of Reclamation in late FY 1969, with financial
support provided by the FWQA. The primary objective of this
project is to develop a digital simulation model that will
accurately predict the quantity and quality of irrigation
return flows from an entire irrigation project with known
soil, groundwater, and geologic and hydrologic characteristics.
Such a model would have several applications. The water
quality impact of a proposed irrigation development could be
more accurately assessed. More importantly, the model could
be utilized to evaluate the water quality effects of
alternative project designs and, therefore, allow selection
of the optimal design of features in order to minimize any
adverse effects on water quality. Another application would
be to evaluate improvements of irrigation facilities and
practices in established irrigated areas aimed at reducing
presently high salt contributions.
Field studies will be conducted in several locations with
various soil and geologic conditions in order to verify
prediction techniques under a wide range of conditions.
Ashley Valley, surrounding Vernal, Utah, was selected as -the
initial study area. Characterization studies of this area
are currently underway. Using present data, initial runs
of an elementary simulation model will be made during 1970.
The model will be refined; additional data will be collected
during the next three years; and field studies at other
locations will be initiated.
(3) The "Grand Valley Salinity Control Demonstration
Project" at Grand Junction, Colorado, was initiated in FY 1969
under a FWQA demonstration grant. Its objective is to
demonstrate the salinity control potential of lining
irrigation canals and laterals. The Grand Valley is underlain
by an aquifer containing highly saline groundwater. Seepage
from canals and laterals contributes to recharge of this
aquifer and displaces the saline groundwater into the
Colorado River, thereby increasing its salt load. Reduction
of such recharge by reducing seepage from conveyance systems,
is therefore, expected to reduce the salt load discharged to
the river.
A major portion of the canals and some of the laterals serving
a study area of about 4,600 acres have been lined and additional
lining will be completed during the 1970-1971 winter season.
A simulation model is being developed which will evaluate the
effects of changes in irrigation efficiency on salt load
contributions, as well as changes in seepage losses from
the conveyance system. Upon completion this model will not
37
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only allow the results of the demonstration project to be
projected valley-wide, but also form the basis for future
salinity control activities in Grand Valley. Completion of
the demonstration project, including all post-construction
studies, is scheduled for mid-1972.
(4) Only limited research efforts are presently directed
toward defining processes to control salt loading from
natural sources. The FWQA provided financial support to
Utah State University for one such effort, "The Electric
Analog Simulation of the Salinity Flow System within the
Upper Colorado River Basin." Results from this research
provided new information concerning the distribution of
salt sources in the Upper Basin and will serve as a potential
analytical tool for evaluating the water quality effects
of various salinity control measures. The final research
report is scheduled for publication during 1970.
(5) In late 1969 a research project entitled "Effect of
Water Management on Quality of Groundwater and Surface
Recharge in Las Vegas Valley," was initiated by Desert
Research Institute, Las Vegas, Nevada, under a FWQA research
grant. Among other things this project will evaluate the
movement of salts in the groundwater system and the exchange
of salts between the groundwater and surface waters of
Las Vegas Wash. Research results will help define the
optimum approach for control of this salt source. Completion
of the research effort is scheduled for mid-1973.
(6) A cooperative regional research effort, "Project W-107,
Management of Salt Load in Irrigation Agriculture," was
initiated in 1969 by seven western universities and the
U. S. Salinity Laboratory of the Agricultural Research
Service. Work currently underway or planned, covers a wide
range of salinity management aspects and should provide a
number of results which can be applied to Basin salinity
problems. The FWQA is participating in the coordination
of this research effort.
SALINITY CONTROL PROJECTS
During the latter part of FY 1968, the FWQA made funds
available and requested the Bureau of Reclamation to select
a pilot project to test and demonstrate control methods for
reducing salinity concentrations and salt loads in the
Colorado River system. The plugging of two flowing wells,
the Meeker and Piceance Creek wells near Meeker, Colorado,
was selected as the pilot demonstration project. Completion
of the well plugging in August, 1968 reduced the salinity
load of the White River and the Colorado River system by
about 62,500 tons annually. This is approximately 19 percent
38
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of the average annual salinity load in the White River near
Watson, Utah. Plugging the Meeker and Piceance Creek wells
initially decreased the annual flow of the White River by
about 2,380 acre-feet. In the opinion of the Bureau's
regional geologist, however, this flow will reappear through
natural springs nearer the recharge area at an improved
quality, and plugging the wells will not decrease the
annual flow of the White River. Costs for plugging the two
wells totaled about $40,000.
Another flowing well near Rock Springs, Wyoming, which
contributed approximately 5,000 tons of salt annually, was
plugged in November 1968, under the direction of the Wyoming
State Engineer. The effects of eliminating this salt source
have not been evaluated.
In late 1969, the Utah Oil and Gas Commission plugged seven
abandoned oil test wells near Moab, Utah, including two
flowing wells which formerly contributed a salt load of
approximately 33,000 tons per year to the Colorado River.
Costs of plugging the wells totaled about $35,000.
It is estimated that plugging the five flowing wells in
Colorado, Wyoming, and Utah will reduce the average annual
salt load passing Hoover Dam by 100,000 tons or 0.93 percent.
Under present conditions this salt load reduction would
reduce average salinity concentrations by about 6 mg/1.
Although this change in salinity concentrations is small
when compared to present salinity levels, the resulting
economic benefits are significant. These benefits are
estimated to range annually from $0.4 million in 1970 to
$1.0 million in 2010 and have a present worth of more than
$10 million.
39
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CHAPTER VII. ALTERNATIVES FOR MANAGEMENT AND CONTROL OF SALINTIY
Three basic approaches, or a combination of these approaches
might be used to achieve a solution to the salinity problem:
do nothing, limit development or implement salinity controls.
The first approach would achieve no management of salinity.
Water resource development would be allowed to proceed with
no constraints applied because of water quality degradation
and with no implementation of salinity control works. This
approach, in effect, ignores the problem and allows
unrestrained economic development at the expense of an
increased adverse economic impact resulting from rising
salinity concentrations. The increases in future salinity
levels and economic impact associated with this approach
have been discussed in Chapter IV.
The second approach would limit economic or water resource
development that is expected to produce an increase in salt
loads or streamflow depletions. Such an approach would
minimize future increases in the economic impact of salinity
and possibly eliminate the need for salinity control facilities.
However, it has the obvious disadvantage of possibly
stagnating growth of the regional economy. Projections of
future salinity levels and associated salinity detriments
for this approach have been discussed in Chapter IV.
The third approach, calling for the construction of salinity
control works, would allow water resource development to
proceed. At least three possible management objectives could
be considered: (1) salinity controls could be implemented
to maintain specific salinity levels; (2) salinity could be
maintained at a level which would minimize its total economic
impact; and (3) salinity could be maintained at some low
level for which the total economic impact of salinity would
be equal to the impact that would be produced if no action
were taken at all.
The following sections discuss an evaluation of the costs
and benefits of various levels of salinity control and a
comparison of the relative economics of the three basic
salinity management approaches discussed above. This
comparison forms the basis for the determination that the
implementation of a basinwide salt load reduction program is
the most feasible approach to achieving basinwide management
of salinity.
POTENTIAL ALTERNATIVE BASINWIDE SALINITY CONTROL PROGRAMS
The potential measures for managing and controlling salinity
concentrations presented in Chapter V were evaluated, and
those which appeared most practical were selected for
further investigation. Eight potential alternative salinity
40
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control programs incorporating a variety of control measures
were formulated as a means of evaluating the magnitude, scope,
and economic feasibility of a potential basinwide control
program. These alternatives include three salt-load
reduction programs, four flow augmentation programs, and one
program to demineralize water supplies at the point of use.
The three salt load reduction programs utilized control
measures such as desalination or impoundment and evaporation
of mineral spring discharges, irrigation return flows and
saline tributary flows, diversion of streams, and improvement
of irrigation practices and facilities. These programs
would acheive estimated salt load reductions of up to three
million tons annually and would reduce average annual salinity
concentrations at Hoover Dam by about 200 to 300 mg/1.
The four flow augmentation programs evaluated were based on
three potential sources of water: increased precipitation
through weather modification, interbasin transfer of water,
and importation of demineralized sea water. The volume of
flow augmentation provided by these programs would range from
1.7 to 5.9 million acre-feet annually. Resulting reductions
in annual salinity concentrations at Hoover Dam would range
from 100 to 300 mg/1.
The last alternative program evaluated would utilize
desalination of the water supplies diverted to southern
California as a means to minimize the adverse impact of
salinity on the southern California water service area.
Average annual costs including amortized construction costs,
operation costs, and maintenance costs, were estimated for
each alternative program and ranged from $3 million to $177
million annually. The present worth of total program costs
for each alternative from 1975 to 2010 would range from $30
million to $1,570 million. Estimated costs and resulting
salinity concentrations are shown by program in Table 7.
If no control or augmentation program were undertaken,
comparable average salinity concentrations at Hoover Dam
would be 876 mg/1 and 990 mg/1 in 1980 and 2010 respectively.
Specific details used to compare and evaluate each alternative
program are discussed in Appendix C, Chapter V.
The eight alternative programs evaluated were not directly
comparable due to differences in the level of salinity
control achieved, the multi-purpose aspects of some programs
versus the singular salinity control natures of others, and
the time required for implementation. Based on evaluation of
a number of factors including total program costs,
practicality, the implementation time period, salinity control
benefits, and other benefits such as increased water supply,
the phased implementation of a salt load reduction program
41
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was selected as the least cost alternative for achieving
basinwide management and control of salinity. Should the
practicality of flow augmentation by weather modification
be demonstrated by current pilot studies, however, the
combination of such flow augmentation with a salt load
reduction program would be a more optimal approach.
SALINITY MANAGEMENT COSTS
If salinity concentrations are reduced by the implementation
of control measures, certain costs known as salinity manage-
ment costs will be incurred. The form and magnitude of these
costs depend upon a number of factors including the control
measures utilized and the degree of salinity control achieved.
Estimates of the probable costs and effects of the salt load
reduction program, were utilized to evaluate the magnitude
of salinity management costs for various levels of salinity
control.
The major features of the salt load reduction program are
presented in Table 8. This program was designed to reduce
the salt load contributed by five large natural sources and
twelve irrigated areas totaling 600,000 acres. Together,
the five natural sources contribute about 14 percent of the
Basin salt load. All of the irrigated areas selected
exhibit high salt pick-up by return flows of about three
to six tons per acre per year. Although this acreage
comprises only about 20 percent of the Basin's irrigated
load from irrigation sources above Hoover Dam. The specific
control measures for the 17 component projects are listed in
Table 8 along with project locations (also shown in Figure
5) .
Average annual costs, including operation, maintenance, and
amortized construction costs, were estimated for each of the
17 projects. For the five single-purpose salt load reduction
projects, all costs were assigned to salinity control. The
irrigation improvement projects would be multi-purpose. It
is estimated they would produce various economic benefits of
about the same magnitude as salinity control benefits and
for this reason, only half of the costs of irrigation
improvement were allocated to salinity control.
Estimates of the changes in streamflow depletions and salt
load reductions were also prepared for each project. The
five salt load reduction projects would remove an average
of 172,000 acre-feet per year from the river system above
Hoover Dam; of this amount, 140,000 acre-feet of demineralized
water from the Blue Springs project would be available for
use in central Arizona. The irrigation improvement projects
would reduce non-beneficial consumptive water use by an
estimated average of 299,000 acre-feet per year. The
43
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LEGEND
k. SALT LOAD REDUCTION PROJECT
RRIGATION IMPROVEMENTS
HENRY'S FORK
ASHLEY CREEK
DUCHESNE AREA
BIG SANDY CREEK
-"SUB1
GUNNISON
PAHGRE
AREA
MUH _ 1
I! I Id
Figure 5. Location of Potential Salt Load Reduction Projects
-------
salinity control program would thus result in a net increase
in available basin water supply of more than 250,000 acre-
feet per year.
The incremental reductions in average salinity concentrations
at Hoover Dam were estimated for each control project for
the years 1980 and 2010 by utilizing predicted changes in
flow and salt load. These incremental changes are shown
in Table 8. Note that the salinity reduction for each
project is greater in the year 2010 than in 1980. This
factor results from decreases in average streamflow predicted
to occur between 1980 and 2010.
A cost index utilizing estimated costs and salt load reductions
was computed for each project. This index was then used to
rank the projects in order of increasing unit cost of salt
removal.
By utilizing the data in Table 8, salinity management cost
functions relating cumulative salinity management costs to
salinity reductions were prepared. These cost functions are
also shown in Figure 6.
TOTAL SALINITY COSTS
For a given salinity level, there is an economic cost
associated with water use (salinity detriments) and a second
economic cost associated with maintaining salinity concent-
rations at that level (salinity management costs). The sum
of these costs, defined as total salinity costs, can be
determined for any time period and salinity level by the
proper manipulation of three factors: the salinity detriment
functions presented in Chapter IV, (Figure 4); the salinity
management cost functions, (Figure 6); and the predicted
future salinity concentrations with no control implemented,
(Figure 2). Total salinity cost functions for various time
periods are presented in Figure 7. The methodology utilized
to develop these functions is discussed in Appendix C,
Chapter V.
ECONOMIC AND WATER QUALITY EFFECTS
Salinity controls could be implemented to meet a variety of
salinity management objectives which include both water
quality and economic objectives. Since salinity levels and
total salinity costs are interrelated, the selection of a
water quality objective will result in the indirect selection
of associated economic effects; conversely, the selection
of an economic objective will result in the selection of
associated salinity levels. A knowledge of the interrelation-
ships between economic and water quality effects is thus
46
-------
100 200 300 400
CUMULATIVE TOTAL DISSOLVED SOLIDS REDUCTIONS (MG/L]
Figure 6. Salinity Management Costs
-------
50
± 40
CO
30
20
10
600 700 800 900 1000
TOTAL DISSOLVED SOLIDS CONCENTRATIONS MG/L AT HOOVER DAM
Figure 7. Total Salinity Costs
-------
useful in the rational selection of salinity management
objectives.
By utilizing the total cost functions shown in Figure 7, the
economic and water quality effects associated with the three
salinity management objectives were determined: (1) Maintain
salinity at a level which would minimize its total economic
impact and achieve economic efficiency (minimum cost objective);
(2) Maintain salinity concentrations at some specified level
(constant salinity objective); and (3) Maintain salinity at
some low level for which the total economic impact would be
equal to the economic impact that would be produced if no
action were taken at all (equal cost objective). A
comparison of the economic effects associated with these
three objectives, in the form of variations in salinity costs
with time, are shown in Figure 8. The economic effects
associated with allowing unlimited water resource development
in the absence of salinity control works (no control approach)
and associated with the limited development approach are
also shown in Figure 8.
Total salinity costs would be minimized by the limited
development alternative. This approach might not be the
most economical, however, when all effects on the regional
economy are measured. Water resource developments are not
constructed unless it has been demonstrated that such
development will return economic benefits which exceed all
costs of the development. A project which is economically
feasible will thus produce a net improvement in the regional
economy. If the project is not built, the net benefits of
the project would be foregone representing an economic
cost. A determination of the net economic benefits fore-
gone if the limited development approach were utilized was
beyond the scope of the Project's investigations. It is
apparent from Figure 8, however, that if the annual benefits
foregone exceed $3 million in 1980 and $11 million in 2010,
the total economic impact of limited development would exceed
the impact of the minimum cost alternative.
If unrestricted water resource development is permitted,
implementing salinity controls to achieve the minimum cost
objective would minimize total salinity costs. The no
control and equal cost alternatives produce the identical
highest average costs and most rapid increase with time of
all the alternatives evaluated. Total costs associated with
a constant salinity objective will fall somewhere between
the extremes established by the other alternatives with
the exact cost dependent upon the target salinity level.
For a target level of 700 mg/1, total costs approximate
minimum costs until 1990, then increase rapidly, eventually
exceeding the no control costs. Beyond the year 2000, the
49
-------
rapidly increasing cost reduce the practicality of
maintaining this salinity level. Selection of a higher
target salinity concentration for the years 2000 and 2010
would reduce the total cost of this alternative.
One important observation can be made from Figure 8. Regard-
less of the alternative selected, the future economic impact
of salinity will be great. Although implementing salinity
controls will result in the availability of better quality
water for various uses and some of the economic impact will
be shifted from salinity detriments to salinity management
costs, the total economic impact of salinity will not be
substantially reduced. As a minimum, average annual total
salinity costs will increase threefold between 1960 and 2010.
Selection of the limited development alternative would reduce
total annual costs by only about 40 percent below the no
control alternative in the year 2010.
Variations with time of the predicted salinity levels
associated with the five alternatives evaluated are shown in
Figure 9. With no controls implemented, average annual
salinity concentrations at Hoover Dam are predicted to
increase between 1960 and 2010 by about 42 percent or 293 mg/1,
Selection of any of the other alternatives evaluated would
substantially reduce future salinity concentrations below
the no control levels. Except for the limited development
alternative, these reductions would result in the maintenance
of average salinity concentrations at or below present
(1970) levels for more than 25 years. Resulting water quality
therefore would be consistent with non-degradation provisions
of the water quality standards adopted by the seven Basin
States. The limited development alternative would result in
slight increases in average salinity concentrations.
COST DISTRIBUTIONS AND EQUITY CONSIDERATIONS
Although the total economic impact of salinity associated with
each of the alternatives evaluated varies over a limited
range, the distribution of salinity costs related to each
alternative differs greatly. Distribution of costs may
therefore be an important factor in the selection of
alternatives. Associated with cost distribution are various
equity considerations. These, too, influence the selection of
alternatives. Salinity cost distributions for the five
alternatives evaluated for both 1980 and 2010 conditions of
water use are compared in Table 9. A further breakdown of
salinity management costs, by individual projects, is shown
in Table 8.
The no control and equal cost alternatives produced the
extremes in the range of cost distributions evaluated. Total
50
-------
Salinity
A Equal Coil
Limited Development
1960 1970
1980 1990
YEAR
2000
2010
Figure 8. Salinity Costs vs Time
-------
1000
Constant Sa.linity
500
1960 197O
198O 199O
YEAR
2OOO 2O1O
Figure 9. Salinity Concentration vs Time
-------
costs for these two alternatives, by definition, are equal
but the distributions of costs are vastly different. For
the no control alternative, all costs are in the form of
detriments. For the equal cost alternative, however, salinity
detriments are reduced by an average of 60 percent. This
cost reduction is offset by a corresponding increase in
salinity management costs.
The extremes in the range of cost distribution point out the
basis for equity considerations which may enter into the
selection of management objectives. If the no control
alternative is selected, all salinity costs would essentially
be borne by water users and by the regional economy in the
Lower Basin and southern California water service area. In
contrast, selection of the equal cost alternative would
redistribute a majority of the costs to investments in
salinity control facilities in the drainage area upstream
from Hoover Dam. Much of this investment would be for
irrigation improvements in the Upper Basin, improvements
that would produce substantial economic benefits in addition
to salinity control benefits. The equity of these two
extremes in cost distributions is vastly different.
Salinity detriments for the other three alternatives
evaluated fall between the extremes extablished by the
no control and equal cost alternatives. Salinity management
costs are less than for the equal cost alternative. The
equity of these cost distributions may also be an important
factor in selection of the most desirable alternative. The
cost distribution shown in Table 9 can be used to evaluate
the relative costs and benefits of a given alternative. For
example, a salinity control program designed to meet the
minimum cost objective would have an estimated average annual
cost of $7.2 million in 1980 and $12.7 million in 2010. The
benefits associated with a given alternative would be the
difference between salinity detriments expected if no controls
are implemented and if the control program associated with
that alternative is implemented. For the minimum cost
alternative, average annual salinity control benefits would
total $10.7 million in 1980 and $22.0 million in 2010.
LEGAL AND INSTITUTIONAL CONSTRAINTS
Implementation of a basinwide salinity control program based
on salt load reduction projects would face a number of legal
and institutional constraints. Perhaps one of the most
formidable constraints would be imposed by existing State
water laws and their requirements concerning water rights
and beneficial use. These laws do not recognize utilization
of water for quality control purposes as a beneficial use,
yet several of the salt load reduction projects formulated
would result in some minor depletion of water. Modification
53
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of existing constraints would therefore be required to allow
operation of these project facilities.
Improvement of irrigation efficiencies would reduce the
amount of water required for diversion to a given farm or
irrigation project. The effect of such a reduction in water
use on perfected water rights is unclear and could cause
legal problems. Such legal factors may affect the selection
of control measures to be incorporated in a basinwide salinity
management program.
The Water Quality Act of 1965 provided that the States establish
water quality standards for all interstate streams. Sub-
sequently, the seven Basin States developed water quality
standards for the Colorado River. The standards established
by the States did not include numerical salinity standards,
primarily due to a lack of adequate salinity control inform-
ation on which an implementation plan could be based. The
Secretary of the Interior approved the water quality standards
for the Colorado River, with the provision that numerical
salinity standards would be established at such a future
time when sufficient information had been developed to
provide the basis for workable, equitable, and enforceable
salinity standards. The states are thus still faced with
the task of establishing suitable salinity standards in
compliance with the Water Quality Act of 1965. The lack of
numerical salinity standards may be a constraint to the
rational planning of water resources development and
implementation of salinity controls.
An important institutional factor for consideration is the
lack of a single entity with basinwide jurisdiction to direct
and implement a salinity control program. In addition, water
quality and water quantity considerations are generally under
the jurisdiction of different agencies at both the State
and Federal level. This split jurisdiction poses coordination
problems to all interests affected by a salinity control
program.
Existing legal and institutional arrangements would also place
constraints upon the means available to finance a salinity
control program. In addition, a detailed analysis has not
yet been made of the potential means for financing such a
program. A cursory review of programs available for financing
facilities similar to those contemplated indicated that
existing financing schemes are not fully adequate to meet
salinity control program needs. This is due either to an
insufficient magnitude of available funds or a lack of legal
authorization.
55
-------
OTHER CONSIDERATIONS
The least cost alternative program, utilized as the basis
for the evaluation of the economic feasibility of salinity
control, was directed toward the objective of minimizing
salinity concentrations on a basinwide basis. This objective
was achieved by reducing the average salt load passing
Hoover Dam, a control point for the quality of water
delivered to most Lower Basin and all Southern California
water users. It is important to note that salinity con-
centrations increase substantially between Hoover Dam and
Imperial Dam due to water use in the Lower Basin and exports
of water to the Metropolitan Water District of Southern
California. Implementation of salinity control measures
along the Lower Colorado River could offset or minimize
these salinity increases. Such measures have a higher unit
cost for salinity reductions at Imperial Dam than those
measures selected for the least cost program and were omitted
from consideration for this reason. Salinity control below
Hoover Dam, however, is a possible, practical approach toward
minimizing the economic impact of salinity and should receive
further consideration in the formulation of a basinwide
salinity control program.
Fluctuations in salinity concentrations resulting from
factors such as seasonal changes in streamflow and water use
occur throughout the Basin. Peak concentrations reached during
such fluctuation may exert adverse effects on water use far
exceeding the effects predicted on the basis of average
salinity concentrations. By reducing average salinity
concentrations, a salt load reduction program would provide
a moderating effect on peak concentrations. The possible
magnitude of such fluctuations and their adverse impact,
however, would indicate the need for more positive means of
minimizing peak concentrations. Possible control measures
would include the manipulation of reservoir storage and
releases, close control of water deliveries to minimize stream
fluctuations, and seasonal storage of salts in irrigated
areas. The water quality simulation model utilized to
predict future salinity concentrations only determines long
term average concentrations and does not have the capability
to predict the magnitude of short term fluctuations. Water
quality simulation capabilities therefore will need to be
refined before the effectiveness of control measures can
be evaluated.
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CHAPTER VIII. ACTION PLAN FOR SALINITY CONTROL AND MANAGEMENT
The preceding chapters defined the present and expected
future magnitude of the physical and economic impacts of
salinity. Possible technical solutions to minimize these
impacts including alternative approaches to management of
salinity and associated water quality and economic effects
were also discussed. The range of possible problem solutions
point out the need for rational selection by the Basin
states of objectives for future water quality and uses and
the formulation of a basinwide salinity control plan to meet
these objectives. This Chapter outlines a recommended plan
of action to achieve an early solution to the salinity
problem in the Colorado River Basin.
BASIC WATER QUALITY OBJECTIVE
In the past, the development of the Basin's water resources
was primarily guided by two basic objectives: (1) full
development of the water supply allocated to each State by
applicable water laws and compacts, and (2) expansion of the
regional economy. A number of legal, institutional and
political factors have supported these basic objectives.
The lack of consideration given to the water quality impact
of such development has resulted in the creation of a
serious water quality problem which has basinwide economic
significance. There is thus the urgent need for a water
quality objective to supplement these basic objectives and
provide guidance in the optimal development of remaining
water resources.
The Project's investigations have demonstrated that basinwide
control and management of salinity is possible, practical
and economically feasible. In addition, the feasibility
of maintaining salinity concentrations at or below present
levels in the Colorado River below Hoover Dam has been shown.
The enhancement of water quality in the lower river would
alleviate much of the future economic impact of salinity.
Enhancement of the quality of the Nation's water resources
has been declared a national policy. It is therefore
recommended that a broad water quality objective be adopted
by Basin interests which would require salinity concentrations
to be maintained at or below present levels in the Lower
Colorado River. This objective would become part of the basic
policy guiding the comprehensive planning and development
of the Basin's remaining water resources.
Salinity Standards
The present lack of numerical limits on salinity concentrations
is a serious deficiency in the water quality standards
established by the seven Basin States for the Colorado River
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and interstate tributaries. Salinity affects a number of
water uses which are designated as uses to be protected by the
standards. Suitable limits should be established to provide
adequate protection for these designated uses.
In the initial process of establishing water quality standards
pursuant to the Water Quality Act of 1965, salinity standards
were not established, primarily due to a lack of information.
Salinity levels which could be maintained by implementing
controls were not known. More significantly, the economic
effects of maintaining any given salinity level were also
unknown. The Project's investigations have provided much of
the needed information. Although additional effort will be
required to establish detailed basinwide criteria which are
equitable, v/orkable and enforceable, present information is
considered adequate to form the basis for the establishment
of a salinity objective which will set an upper limit on
salinity increases in the Lower Colorado River.
It is recommended that appropriate Colorado River Basin
States take the steps necessary to establish a numerical
objective for salinity concentration. Based on the factors
discussed below, it is recommended that, as a minimum,
this objective require the average concentrations of total
dissolved solids for any given month to be maintained below
1000 mg/1 at Imperial Dam. This would apply until such
time as detailed basinwide criteria can be established as
discussed in the following section.
Evaluation of the water quality effects of various salinity
control alternatives has shown that by either implementing
a basinwide salinity control program or limiting water
resource development, future salinity levels at Hoover Dam
could be maintained at or below an average annual concentration
of 800 mg/1. A corresponding limit of 1000 mg/1 at Imperial
Dam could be achieved. A maximum limit based on average
annual salinity concentrations would not provide water uses
with adequate protection against potentially damaging short-
term salinity fluctuations. A limit on average monthly
concentrations is considered necessary to provide a more
acceptable level of protection.
To achieve compliance with the basic policy objective to
enhance water quality in the Lower Colorado River will require
that detailed salinity criteria be established at a number
of key locations throughout the Basin. These criteria will
serve two purposes. By maintaining salinity levels at
upstream locations below assigned limits, compliance with
downstream criteria will be assured. Secondly, the
criteria will provide a basis for optimal development of
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the water resources of a given tributary, sub-basin or
State.
Complete Basinwide salinity criteria should be established
after careful consideration by the Basin interests of such
factors as existing salinity levels, proposed water resources
development, the feasibility of salinity control, water
quality requirements for water uses, and the economic impact
of salinity. Such criteria should be consistent with the
salinity policy and with the numerical objective outlined
above, and should be adopted by January 1, 1973.
It is recommended that a State/Federal task group be
established immediately to carry out the necessary activities
to develop detailed salinity criteria for key control points
in the Basin. Following completion of the Task Group's
activities, the salinity criteria should be adopted by the
appropriate Basin States in accordance with the Federal
Water Pollution Control Act, as amended.
Task groups have been utilized in a similar manner in the
Basin in the past. A task group was assembled to develop
guidelines for establishing the initial water quality
standards in the Basin. More recently, a task group was
utilized to develop operating criteria for the large main-
stem reservoirs.
To provide adequate consideration of all interests affected
by salinity, the Task Group should include representation
from Federal, State and local agencies. It would be
desirable for state representation to include the State
water pollution control agency and the State water resource
agency. In view of Federal involvement in water resource
development, water quality management, and the basinwide
nature of the salinity problem Federal representation should
include the Environmental Protection Agency, the Bureau
of Reclamation, the Geological Survey, the Office of Saline
Water, the Soil Conservation Service, the Agricultural
Research Service and the International Boundary and Water
Commission. Representation from other groups such as the
Upper Colorado River Commission, Colorado River Commission
of Nevada, Colorado River Board of California, and the
Colorado River Water Users Association would be desirable.
SALINITY CONTROL AGENCY
One major constraint that must be overcome before basinwide
management and control of salinity can be achieved is the lack
of a single institutional entity with basinwide jurisdiction
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which could be responsible for planning and implementing
a control program. There are various agencies with
jurisdictions over parts or all of the Basin. In the case
of the States, no suitable basinwide organizations exist.
Several Federal agencies have basinwide responsibilities
but no single agency has legislative authority to carry out
all program elements. It would therefore appear necessary
to create a new institution with the necessary authority
to plan and implement a control program.
Three possible means of creating a salinity control agency
are available. The Task Group assembled to formulate salinity
criteria could continue to function and could be utilized
to develop policy and plan a basinwide salinity control
program. It would be heavily dependent upon member agencies
to carry out the necessary program planning activities. A
Task Group would be severly limited in its authority to
require the States or Federal agencies to proceed with specific
courses of action and would not have the necessary powers
to fully implement a control program. No new legislative
authority would be required to create this somewhat limited
salinity control agency.
A second possible approach would be to extend the authority
of an existing agency or commission to provide the necessary
powers to carry out all the phases of a basinwide salinity
control program. This approach would require changes in the
authorizing legislation for the particular institutional
entity selected for expansion of its functions.
Perhaps the most desirable approach would be to create a
new permanent State/Federal agency or river basin commission
with the authority to carry out all activities necessary to
the basinwide management and control of salinity. Such an
agency would have the advantages of concentrating all
necessary powers in one agency and of being a single purpose
institution with no conflict with other assigned functions.
New legislation would be required to create the agency.
In view of the magnitude and scope of the salinity problem
and possible solutions, it is recommended that the third
approach be taken and that legislation be sought to establish
a permanent State/Federal agency or river basin commission
with the authority to plan, formulate policy, direct, and
implement a basinwide salinity control program. Consideration
should also be given to the possibility of extending the
authority of existing agencies or commissions to assume this
responsibility.
BASINWIDE SALINITY CONTROL PROGRAM
A large-scale salt load reduction program was identified in
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Chapter VII as the least cost alternative means of achieving
basinwide control of salinity. The steps which must be
taken to authorize, fund, plan and implement such a program
are outlined in the following paragraphs.
Legislative Authorization
Existing legal and institutional arrangements are not
adequate to provide the basis for implementing a large-scale
salinity control program. It is therefore recommended that
the necessary congressional authorization and funding be
sought at an early date so that the implementation of the
salinity control program can proceed.
Due to the scale and types of control projects included in
the salt load reduction program an approach similar to that
utilized for the authorization and funding of water resources
developments is recommended. Water resource projects
normally move through three basic steps before they are
placed in operation. A project is first authorized by
Congress on the basis of preliminary plans developed by
limited studies known as reconnaissance studies. Following
authorization, funds may be appropriated for more detailed
planning investigations known as feasibility studies, a
feasibility report is submitted to Congress, and construction
funds are requested. The third step begins when funds are
appropriated for construction. Completion of construction
then places the project in operation.
Frequently, a number of related projects are authorized by
a single legislative act. This was the case for the
Colorado River Storage Project Act which authorized several
large reservoir projects at one time. It is recommended
that legislation be introduced in the near future to authorize
the entire basinwide salt load reduction program and to
appropriate funds for the necessary planning studies.
Planning Phase
In line with the three steps outlined above for authorizing
and funding a water resource project, once authorized, the
basinwide salinity control program should be conducted in
two phases, a planning phase and an implementation phase.
This section outlines the activities which make up the
planning phase.
The planning phase of the basinwide program should be directed
toward the objectives of providing sufficient information
for developing an implementation plan, and of providing the
feasibility reports on which requests for construction funds
for necessary control works can be based, and of identifying
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construction, operation and related costs which should be
properly assigned to the Basin States and other beneficiaries.
To achieve these objectives will require substantial efforts
to be expended in five types of activity: systems analyses,
research and demonstration activities, reconnaissance
investigations, feasibility studies and legal, institutional
and financial evaluations.
System Analyses. A systematic evaluation of the quality
and economic aspects of the salinity problem provided a key
element in the Project's determination of the potential
feasibility and practicality of a basinwide salinity control
program. Systems analysis capability similar to the
methodology developed for this evaluation will be required
for the planning phase. Refinement and updating of the
analytical tools will be required, however, to provide
adequate capability for the improved information developed
by other planning activities. Specifically, a refined water
quality simulation model and updated economic evaluation
models will be required.
The Project's water quality simulation model is basically a
water and salt budget model with the capability to predict
long term averages for streamflow, salt loads and salinity
concentrations at various points in the basin and to evaluate
the long term effects of modifications in water use and salt
loading at any point in the river system. This model is not
capable of predicting fluctuations in salinity concentrations
or of evaluating the short term effects of various control
measures. The model should be refined to provide for
simulation of water quality on a monthly basis including the
routing of salt loads through irrigated areas and large
reservoirs. This improved model would have the capability
to evaluate the water quality effects of proposed annual
operating plans for the major reservoirs of the basin, to
optimize reservoir operations to minimize salinity fluctuations,
to provide an improved degres of evaluation of the salinity
impacts of proposed water resource development projects and
to assist in the formulation of suitable numerical salinity
standards in addition to its utilization for evaluation of
alternative salinity control measures and facilities.
The Project's economic evaluations and models were largely
based on 1960 economic data. The economic impact of salinity
increases in specific areas in the Upper Basin and Mexican
water users was not evaluated. The effects of rising salinity
levels in the Colorado River supply on the feasibility of
controlling the salinity of the Salton Sea was not considered.
Economic effects were based on average salinity concentrations
and fluctuations in concentrations were not evaluated.
Updating the economic models on the basis of 1970 economic
data which should be available by 1972 would provide a better
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estimate of the current detrimental effects of salinity and
would improve predictions of future effects since historical
trends from 1960 to 1970 would be available. In view of
the probable economic impact of salinity on Mexican water
users, on water use in certain areas of the Upper Basin and
on control of salinity in the Salton Sea, the economic models
should have the capability for handling such areas. In
addition, the capability to evaluate the economic impact of
salinity fluctuations should be developed.
Research and Demonstration Activities. A number of research
and demonstration activities discussed in Chapter V are
currently directed toward improvement of salinity control
technology. Completion of these activities will not provide
the technology needed for control of all types of salinity
sources. Additional research will be required if certain
types of salinity sources are to be controlled.
The greatest lack of available technology is in the area of
natural diffuse sources. Control of salt contributed by
surface runoff and diffuse groundwater sources, although
the major sources of salt-loading in the Basin, is presently
not technically feasible. The Soil Conservation Service, the
Bureau of Reclamation, the Geological Survey, the Bureau of
Land Management and various State agencies are all concerned
with various aspects of water and land utilization which may
have an impact on diffuse salt contributions. It may be
possible to conduct research or demonstration efforts through
these agencies programs to develop means of minimizing diffuse
salt contributions.
Control measures applicable to natural point sources are
limited, especially in areas with low evaporation rates. The
Geological Survey has an extensive reserach program in the
field of groundwater quality and movement. Directing some
of this research effort toward mineral springs could result
in the development of additional control measures.
Another area for which present control technology is limited
is irrigated agriculture. Research concerning various
irrigation practices and facilities, crop yields, and land
characteristics being carried out by various State institutions,
the Bureau of Reclamation, the Soil Conservation Service and
the Agricultural Research Service may be expanded to include
salinity control aspects.
Reduction of salt loads from irrigated agriculture utilizing
present technology as contemplated for the salt load reduction
program previously discussed will require the education of
irrigators with regard to improved practices and will require
a substantial investment by irrigators for improved facilities.
Demonstrations of the economic benefits associated with
proposed improvements will be required to provide the incentive
for irrigators to make the necessary changes. Such
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demonstrations would also show the technical feasibility
of such control measures with regard to water quality
improvements. The Bureau of Reclamation, the Soil
Conservation Service, the Agricultural Stabilization and
Conservation Service, the Extension Service, various water
user's associations and other state agencies conduct
programs which could assist in such education and demon-
stration efforts.
Completion of reconnaissance and feasibility studies
discussed in the following sections will be dependent upon
completion of research and demonstration activities in
some cases. This fact coupled with the time span required
for completion of most research efforts would indicate the
need for early initiation of desired additional research
and demonstration efforts.
Reconnaissance Investigations. Preliminary, limited scope
investigations known as reconnaissance investigations were
completed in sufficient detail to provide the basis for
seeking appropriations of funds for feasibility studies for
only two of the seventeen projects included in the salt
load reduction program. Reconnaissance investigations
would thus be required for the other 15 projects. In
addition, similar investigations should be made of control
measures along the Lower Colorado River below Hoover Dam,
in the Yuma Valley area with respect to the salinity of
Mexican water deliveries and in the Salton Sea area where
such controls might alleviate rising salinity levels in the
Sea. Such investigations could best be performed by the
water resource development agencies at both the State and
Federal level. The Bureau of Reclamation is currently
conducting a planning study for rehabilitation of irrigation
facilities for the Uncompahgre Project, Colorado, which
could be expanded to include the desired salinity control
reconnaissance investigation.
An evaluation of the results of the reconnaissance invest-
igations would provide the basis for initiation of feasibility
studies for those control projects showning economic
feasibility at the reconnaissance level.
Feasibility Studies
Feasibility studies are planning studies which go into much
greater detail than reconnaissance investigations and
frequently require extensive and costly field investigations.
For this reason, such studies should be conducted for
only those control projects which could reasonably be
constructed to meet salinity management objectives. Such
studies would provide the basis for seeking appropriations
for actual project construction.
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Legal and Institutional Evaluation
Constraints imposed by legal and institutional factors may
significantly alter the range of available salinity control
measures. Detailed evaluations of existing legal and
institutional constraints which may affect the basinwide
salinity control program should be conducted. Where
modifications of existing legislation or institutional
arrangements are needed to allow a rational approach to
management of salinity, such modifications should be
identified. Emphasis should be placed on evaluations of
the various water laws controlling use and distribution of
Colorado River water.
Implementation Phase
The final or implementation phase of the basinwide control
program would include the appropriation of construction
funds, the actual construction of projects, and the actual
management of salinity through operation of control works.
As feasibility studies are completed, a final implementation
plan should be developed which would be directed toward
meeting the established numerical salinity standards.
Feasibility reports for the control projects included in
the final plan should then be submitted to Congress and
construction funds requested. Funds should be made available
according to the construction schedule established by the
implementation plan. Since the implementation of control
works will be dependent to some extent upon the rate at
which water resources development proceeds, the actual
construction of control projects could extend over a lengthy
period.
Once control measures are implemented, provision will need to
be made for funding for continued operation and maintenance
as most facilities will be need continuously for the fore-
seeable future.
" -ft GPO 790-485
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